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Sample records for conifers

  1. Ecophysiological controls of conifer distributions

    SciTech Connect

    Woodward, F.I.

    1995-07-01

    The boreal forest covers the most extensive worldwide area of conifer-dominated vegetation, with a total global area of about 12 million km{sup 2}. This large area is very species poor; in North America there are only nine widespread and dominant species of trees, of which six are conifers-Picea mariana, Picea glauca, Abies balsamea, Larix laricina, Pinus contorta, and Pinus banksiana. The remaining three angiosperms are Betula papyrifera, Populus tremuloides, and Populus balsamifera. In Fennoscandia and the former Soviet Union, 14 species dominate the boreal forest, 10 of which are conifers-Abies sibirica, Larix gmelinii, Larix sibirica, Larix sukaczewii, Picea abies, Picea ajanensis, Picea obovata, Pinus pumila, Pinus sibifica, and Pinus sylvestris. The dominant angiosperm trees are Betula pendula, Betula pubescens, Chosenia arbutifolia, and Populus tremula. Such species paucity detracts from realizing the remarkable capacity of these species to endure the harshest forest climates of the world. Both the short-term geological history and the current climate are major causes of the species paucity in the boreal forest. In general, the boreal forest has been present in its current distribution only since the Holocene era. In most cases, the dominant species of the boreal forest completed their postglacial expansion to their current distributions only over the past 2000 years. So the ecology of the forest is very young, in comparison with forests in warmer climates. It might be expected that over subsequent millennia, with no climatic change, there could be a slow influx of new species to the boreal zone; however, the extreme climatic, edaphic, and disturbance characteristics of the area are likely to set insurmountable limits on this influx of diversity.

  2. Defense Mechanisms of Conifers 1

    PubMed Central

    Lewinsohn, Efraim; Gijzen, Mark; Savage, Thomas J.; Croteau, Rodney

    1991-01-01

    Cell-free extracts from Pinus ponderosa Lawson (ponderosa pine) and Pinus sylvestris L. (Scotch pine) wood exhibited high levels of monoterpene synthase (cyclase) activity, whereas bark extracts of these species contained no detectable activity, and they inhibited cyclase activity when added to extracts from wood, unless polyvinylpyrrolidone was included in the preparation. The molecular mass of the polyvinylpyrrolidone added was of little consequence; however, polyvinylpolypyrrolidone (a cross-linked insoluble form of the polymer) was ineffective in protecting enzyme activity. Based on these observations, methods were developed for the efficient extraction and assay of monoterpene cyclase activity from conifer stem (wood and bark) tissue. The level of monoterpene cyclase activity for a given conifer species was shown to correlate closely with the monoterpene content of the oleoresin and with the degree of anatomical complexity of the specialized resin-secreting structures. Cyclase activity and monoterpene content were lowest in the stems of species containing only isolated resin cells, such as western red cedar (Thuja plicata D. Don). Increasing levels of cyclase activity and oleoresin monoterpenes were observed in advancing from species with multicellular resin blisters (true firs [Abies]) to those with organized resin passages, such as western larch (Larix occidentalis Nutt.), Colorado blue spruce (Picea pungens Engelm.) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). The highest levels of cyclase activity and oleoresin monoterpenes were noted in Pinus species that contain the most highly developed resin duct systems. The relationship between biosynthetic capacity, as measured by cyclase activity, monoterpene content, and the degree of organization of the secretory structures for a given species, may reflect the total number of specialized resin-producing cells per unit mass of stem tissue. PMID:16668182

  3. Diseases of Pacific Coast conifers. Agriculture handbook

    SciTech Connect

    Scharpf, R.F.

    1993-06-01

    The handbook provides basic information needed to identify the common diseases of Pacific Coast conifers. Hosts, distribution, disease cycles, and identifying characteristics are described for more than 150 diseases, including cankers, diebacks, galls, rusts, needle diseases, root diseases, mistletoes, and rots. Diseases in which abiotic factors are involved are also described. For some groups of diseases, a descriptive key to field identification is included.

  4. Montane conifer fuel dynamics, Yosemite National Park

    USGS Publications Warehouse

    van Wagtendonk, J.W.; Moore, P.E.

    1997-01-01

    Litter and woody fuel accumulation rates over 7 years for 7 montane Sierra Nevada conifer species, including giant sequoia, ponderosa pine, sugar pine, Jeffrey pine, incense-cedar and white fir. Data are from four sites per size class per species with four size classes each. Nonspatial, georeferenced.

  5. Genetics and the physiological ecology of conifers

    SciTech Connect

    Mitton, J.B.

    1995-07-01

    Natural selection acts on the diversity of genotypes, adapting populations to their specific environments and driving evolution in response to changes in climate. Genetically based differences in physiology and demography adapt species to alternate environments and produce, along with historical accidents, the present distribution of species. The sorting of conifer species by elevation is so marked that conifers help to define plant communities arranged in elevational bands in the Rocky Mountains. For these reasons, a genetic perspective is necessary to appreciate the evolution of ecophysiological patterns in the coniferous forests of the Rocky Mountains. The fascinating natural history and the economic importance of western conifers have stimulated numerous studies of their ecology, ecological genetics, and geographic variation. These studies yield some generalizations, and present some puzzling contradictions. This chapter focuses on the genetic variability associated with the physiological differences among genotypes in Rocky Mountain conifers. Variation among genotypes in survival, growth, and resistance to herbivores is used to illustrate genetically based differences in physiology, and to suggest the mechanistic studies needed to understand the relationships between genetic and physiological variation.

  6. Fuel bed characteristics of Sierra Nevada conifers

    USGS Publications Warehouse

    van Wagtendonk, J.W.; Benedict, J.M.; Sydoriak, W.M.

    1998-01-01

    A study of fuels in Sierra Nevada conifer forests showed that fuel bed depth and fuel bed weight significantly varied by tree species and developmental stage of the overstory. Specific values for depth and weight of woody, litter, and duff fuels are reported. There was a significant positive relationship between fuel bed depth and weight. Estimates of woody fuel weight using the planar intercept method were significantly related to sampled values. These relationships can be used to estimate fuel weights in the field.

  7. Conifer health classification for Colorado, 2008

    USGS Publications Warehouse

    Cole, Christopher J.; Noble, Suzanne M.; Blauer, Steven L.; Friesen, Beverly A.; Curry, Stacy E.; Bauer, Mark A.

    2010-01-01

    Colorado has undergone substantial changes in forests due to urbanization, wildfires, insect-caused tree mortality, and other human and environmental factors. The U.S. Geological Survey Rocky Mountain Geographic Science Center evaluated and developed a methodology for applying remotely-sensed imagery for assessing conifer health in Colorado. Two classes were identified for the purposes of this study: healthy and unhealthy (for example, an area the size of a 30- x 30-m pixel with 20 percent or greater visibly dead trees was defined as ?unhealthy?). Medium-resolution Landsat 5 Thematic Mapper imagery were collected. The normalized, reflectance-converted, cloud-filled Landsat scenes were merged to form a statewide image mosaic, and a Normalized Difference Vegetation Index (NDVI) and Renormalized Difference Infrared Index (RDII) were derived. A supervised maximum likelihood classification was done using the Landsat multispectral bands, the NDVI, the RDII, and 30-m U.S. Geological Survey National Elevation Dataset (NED). The classification was constrained to pixels identified in the updated landcover dataset as coniferous or mixed coniferous/deciduous vegetation. The statewide results were merged with a separate health assessment of Grand County, Colo., produced in late 2008. Sampling and validation was done by collecting field data and high-resolution imagery. The 86 percent overall classification accuracy attained in this study suggests that the data and methods used successfully characterized conifer conditions within Colorado. Although forest conditions for Lodgepole Pine (Pinus contorta) are easily characterized, classification uncertainty exists between healthy/unhealthy Ponderosa Pine (Pinus ponderosa), Pi?on (Pinus edulis), and Juniper (Juniperus sp.) vegetation. Some underestimation of conifer mortality in Summit County is likely, where recent (2008) cloud-free imagery was unavailable. These classification uncertainties are primarily due to the spatial and

  8. Gondwanan conifer clones imperilled by bushfire

    PubMed Central

    Worth, James R. P.; Sakaguchi, Shota; Rann, Karl D.; Bowman, Clarence J. W.; Ito, Motomi; Jordan, Gregory J.; Bowman, David M. J. S.

    2016-01-01

    Global increases in fire frequency driven by anthropogenic greenhouse emissions and land use change could threaten unique and ancient species by creeping into long-term fire refugia. The perhumid and mountainous western half of Tasmania is a globally important refugium for palaeo-endemic, fire intolerant lineages, especially conifers. Reproductive strategy will be crucial to the resilience of these organisms under warmer, dryer and more fire prone climates. This study analysed clonal versus sexual reproduction in old growth plots dominated by the palaeo-endemic conifer Athrotaxis cupressoides (Cupressaceae), a species that lacks any traits to tolerate frequent landscape fire. Across most of the seven plots the amount of sexually derived individuals was lower than clonally derived with, on average, 60% of all stems belonging to the same multi-locus lineage (MLL) (i.e. were clonal). Some MLLs were large spanning over 10 s of metres and consisted of up to 62 stems. The high mortality after fire and the rarity of sexual regeneration means that the range of this fire-intolerant species is likely to contract under enhanced fire regimes and has a limited capacity to disperse via seed to available fire refugia in the landscape. PMID:27666536

  9. Plant hormones and ecophysiology of conifers

    SciTech Connect

    Davies, W.J.

    1995-07-01

    Over the past 30 years, there have been very substantial fluctuations in the interests of plant scientists in the involvement of plant growth regulators in the control of physiology, growth, and development of plants. In the years following the identification of the five major classes of growth regulators and identification of other groups of compounds of somewhat more restricted interest, an enormous number of papers reported the effects of hormones applied externally to a very wide range of plants. During this period, it became very fashionable to compare effects of hormones with the effects of the environment on developmental and physiological phenomena and to suggest a regulatory role for the hormone(s) in the processes under consideration. Ross et al. (1983) have published a very comprehensive survey of the effects of growth regulators applied externally to conifers, and even 10 years later, it is difficult to improve on what they have done. Nevertheless, in the light of recent changes in our understanding of how growth regulators may work, it is necessary to reexamine this field and ask what we really know about the involvement of growth regulators in the ecophysiology of conifers.

  10. AmeriFlux US-Vcm Valles Caldera Mixed Conifer

    SciTech Connect

    Litvak, Marcy

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Vcm Valles Caldera Mixed Conifer. Site Description - The Valles Caldera Mixed Conifer site is located in the 1200 km2 Jemez River basin in north-central New Mexico. Common to elevations ranging from 3040 to 2740 m in the region, the mixed conifer stand, within the entirety of the tower footprint in all directions, provides an excellent setting for studying the seasonal interaction between snow and vegetation.

  11. Conifer Decline and Mortality in Siberia

    NASA Astrophysics Data System (ADS)

    Kharuk, V.; Im, S.; Ranson, K.

    2015-12-01

    "Dark needle conifer" (DNC: Abies sibirica, Pinus sibirica and Picea obovata) decline and mortality increase were documented in Russia during recent decades. Here we analyzed causes and scale of Siberian pine and fir mortality in Altai-Sayan and Baikal Lake Regions and West Siberian Plane based on in situdata and remote sensing (QuickBird, Landsat, GRACE). Geographically, mortality began on the margins of the DNC range (i.e., within the forest-steppe and conifer-broadleaf ecotones) and on terrain features with maximal water stress risk (narrow-shaped hilltops, convex steep south facing slopes, shallow well-drained soils). Within ridges, mortality occurred mainly along mountain passes, where stands faced drying winds. Regularly mortality was observed to decrease with elevation increase with the exception of Baikal Lake Mountains, where it was minimal near the lake shore and increased with elevation (up to about 1000 m a.s.l.). Siberian pine and fir mortality followed a drying trend with consecutive droughts since the 1980s. Dendrochronology analysis showed that mortality was correlated with vapor pressure deficit increase, drought index, soil moisture decrease and occurrence of late frosts. In Baikal region Siberian pine mortality correlated with Baikal watershed meteorological variables. An impact of previous year climate conditions on the current growth was found (r2 = 0.6). Thus, water-stressed trees became sensitive to bark beetles and fungi impact (including Polygraphus proximus and Heterobasidion annosum). At present, an increase in mortality is observed within the majority of DNC range. Results obtained also showed a primary role of water stress in that phenomenon with a secondary role of bark beetles and fungi attacks. In future climate with increased drought severity and frequency Siberian pine and fir will partly disappear from its current range, and will be substituted by drought-tolerant species (e.g., Pinus silvestris, Larix sibirica).

  12. Early genome duplications in conifers and other seed plants

    PubMed Central

    Li, Zheng; Baniaga, Anthony E.; Sessa, Emily B.; Scascitelli, Moira; Graham, Sean W.; Rieseberg, Loren H.; Barker, Michael S.

    2015-01-01

    Polyploidy is a common mode of speciation and evolution in angiosperms (flowering plants). In contrast, there is little evidence to date that whole genome duplication (WGD) has played a significant role in the evolution of their putative extant sister lineage, the gymnosperms. Recent analyses of the spruce genome, the first published conifer genome, failed to detect evidence of WGDs in gene age distributions and attributed many aspects of conifer biology to a lack of WGDs. We present evidence for three ancient genome duplications during the evolution of gymnosperms, based on phylogenomic analyses of transcriptomes from 24 gymnosperms and 3 outgroups. We use a new algorithm to place these WGD events in phylogenetic context: two in the ancestry of major conifer clades (Pinaceae and cupressophyte conifers) and one in Welwitschia (Gnetales). We also confirm that a WGD hypothesized to be restricted to seed plants is indeed not shared with ferns and relatives (monilophytes), a result that was unclear in earlier studies. Contrary to previous genomic research that reported an absence of polyploidy in the ancestry of contemporary gymnosperms, our analyses indicate that polyploidy has contributed to the evolution of conifers and other gymnosperms. As in the flowering plants, the evolution of the large genome sizes of gymnosperms involved both polyploidy and repetitive element activity. PMID:26702445

  13. Role of quinate dehydrogenase in quinic acid metabolism in conifers

    SciTech Connect

    Osipov, V.I.; Shein, I.V.

    1986-08-10

    Quinate dehydrogenase was isolated from young needles of the Siberian larch and partially purified by ammonium sulfate fractionation. It was found that in conifers, in contrast to other plants, quinate dehydrogenase is active both with NAD and with NADP. The values of K/sub m/ for quinate and NADP were 1.8 and 0.18 mM. The enzyme exhibits maximum activity at pH 9.0. It was assumed that NADP-dependent quinate dehydrogenase is responsible for quinic acid synthesis. The special features of the organization and regulation of the initial stages of the shikimate pathway in conifers are discussed.

  14. Resource physiology of conifers: Acquisition, allocation, and utilization

    SciTech Connect

    Smith, W.K.; Hinckley, T.M.

    1995-03-01

    This book focuses on a synthetic view of the resource physiology of conifer trees with an emphasis on developing a perspective that can integrate across the biological hierarchy. This objective is in concert with more scientific goals of maintaining biological diversity and the sustainability of forest systems. The preservation of coniferous forest ecosystems is a major concern today. This volume deals with the topics of resource acquisition, allocation, and utilization in conifers. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  15. A Simple Computer Application for the Identification of Conifer Genera

    ERIC Educational Resources Information Center

    Strain, Steven R.; Chmielewski, Jerry G.

    2010-01-01

    The National Science Education Standards prescribe that an understanding of the importance of classifying organisms be one component of a student's educational experience in the life sciences. The use of a classification scheme to identify organisms is one way of addressing this goal. We describe Conifer ID, a computer application that assists…

  16. Conifers have a unique small RNA silencing signature

    PubMed Central

    Dolgosheina, Elena V.; Morin, Ryan D.; Aksay, Gozde; Sahinalp, S. Cenk; Magrini, Vincent; Mardis, Elaine R.; Mattsson, Jim; Unrau, Peter J.

    2008-01-01

    Plants produce small RNAs to negatively regulate genes, viral nucleic acids, and repetitive elements at either the transcriptional or post-transcriptional level in a process that is referred to as RNA silencing. While RNA silencing has been extensively studied across the different phyla of the animal kingdom (e.g., mouse, fly, worm), similar studies in the plant kingdom have focused primarily on angiosperms, thus limiting evolutionary studies of RNA silencing in plants. Here we report on an unexpected phylogenetic difference in the size distribution of small RNAs among the vascular plants. By extracting total RNA from freshly growing shoot tissue, we conducted a survey of small RNAs in 24 vascular plant species. We find that conifers, which radiated from the other seed-bearing plants ∼260 million years ago, fail to produce significant amounts of 24-nucleotide (nt) RNAs that are known to guide DNA methylation and heterochromatin formation in angiosperms. Instead, they synthesize a diverse population of small RNAs that are exactly 21-nt long. This finding was confirmed by high-throughput sequencing of the small RNA sequences from a conifer, Pinus contorta. A conifer EST search revealed the presence of a novel Dicer-like (DCL) family, which may be responsible for the observed change in small RNA expression. No evidence for DCL3, an enzyme that matures 24-nt RNAs in angiosperms, was found. We hypothesize that the diverse class of 21-nt RNAs found in conifers may help to maintain organization of their unusually large genomes. PMID:18566193

  17. Analysis of conifer forest regeneration using Landsat Thematic Mapper data

    NASA Technical Reports Server (NTRS)

    Fiorella, Maria; Ripple, William J.

    1995-01-01

    Landsat Thematic Mapper (TM) data were used to evaluate young conifer stands in the western Cascade Mountains of Oregon. Regression and correlation analyses were used to describe the relationships between TM band values and age of young Douglas-fir stands (2 to 35 years old). Spectral data from well regenerated Douglas-fir stands were compared to those of poorly regenerated conifer stands. TM bands 1, 2, 3, 5, 6, and 7 were inversely correlated with the age (r greater than or equal to -0.80) of well regenerated Douglas-fir stands. Overall, the 'structural index' (TM 4/5 ratio) had the highest correlation to age of Douglas-fir stands (r = 0.96). Poorly regenerated stands were spectrally distinct from well regenerated Douglas-fir stands after the stands reached an age of approximately 15 years.

  18. Low-frequency creep in CoNiFe films.

    NASA Technical Reports Server (NTRS)

    Bartran, D. S.; Bourne, H. C., Jr.; Chow, L. G.

    1972-01-01

    Domain wall motion excited by slow rise-time, bipolar, hard-axis pulses in vacuum deposited CoNiFe films from 1500 to 2000 A thick is studied. The results are consistent with those of comparable NiFe films. Furthermore, the wall coercivity is found to be the most significant sample property correlated to the low-frequency creep properties of all the samples.

  19. The Norway spruce genome sequence and conifer genome evolution.

    PubMed

    Nystedt, Björn; Street, Nathaniel R; Wetterbom, Anna; Zuccolo, Andrea; Lin, Yao-Cheng; Scofield, Douglas G; Vezzi, Francesco; Delhomme, Nicolas; Giacomello, Stefania; Alexeyenko, Andrey; Vicedomini, Riccardo; Sahlin, Kristoffer; Sherwood, Ellen; Elfstrand, Malin; Gramzow, Lydia; Holmberg, Kristina; Hällman, Jimmie; Keech, Olivier; Klasson, Lisa; Koriabine, Maxim; Kucukoglu, Melis; Käller, Max; Luthman, Johannes; Lysholm, Fredrik; Niittylä, Totte; Olson, Ake; Rilakovic, Nemanja; Ritland, Carol; Rosselló, Josep A; Sena, Juliana; Svensson, Thomas; Talavera-López, Carlos; Theißen, Günter; Tuominen, Hannele; Vanneste, Kevin; Wu, Zhi-Qiang; Zhang, Bo; Zerbe, Philipp; Arvestad, Lars; Bhalerao, Rishikesh; Bohlmann, Joerg; Bousquet, Jean; Garcia Gil, Rosario; Hvidsten, Torgeir R; de Jong, Pieter; MacKay, John; Morgante, Michele; Ritland, Kermit; Sundberg, Björn; Thompson, Stacey Lee; Van de Peer, Yves; Andersson, Björn; Nilsson, Ove; Ingvarsson, Pär K; Lundeberg, Joakim; Jansson, Stefan

    2013-05-30

    Conifers have dominated forests for more than 200 million years and are of huge ecological and economic importance. Here we present the draft assembly of the 20-gigabase genome of Norway spruce (Picea abies), the first available for any gymnosperm. The number of well-supported genes (28,354) is similar to the >100 times smaller genome of Arabidopsis thaliana, and there is no evidence of a recent whole-genome duplication in the gymnosperm lineage. Instead, the large genome size seems to result from the slow and steady accumulation of a diverse set of long-terminal repeat transposable elements, possibly owing to the lack of an efficient elimination mechanism. Comparative sequencing of Pinus sylvestris, Abies sibirica, Juniperus communis, Taxus baccata and Gnetum gnemon reveals that the transposable element diversity is shared among extant conifers. Expression of 24-nucleotide small RNAs, previously implicated in transposable element silencing, is tissue-specific and much lower than in other plants. We further identify numerous long (>10,000 base pairs) introns, gene-like fragments, uncharacterized long non-coding RNAs and short RNAs. This opens up new genomic avenues for conifer forestry and breeding.

  20. L-Band Radiometer Measurements of Conifer Forests

    NASA Technical Reports Server (NTRS)

    Lang, R.; LeVine, D.; Chauhan, N.; deMatthaeis, P.; Bidwell, S.; Haken, M.

    2000-01-01

    Airborne radiometer measurements have been made at L-band over conifer forests in Virginia to study radiometric response to biomass and soil moisture. The horizontally polarized synthetic aperture radiometer, ESTAR, has been deployed abroad a NASA-P3 aircraft which is based at the Goddard Space Flight Center's Wallops Flight Facility. The instrument has been mounted in the bomb bay of the P-3 and images data in the cross track direction. Aircraft and surface measurements were made in July, August and November of 1999 over relatively homogeneous conifer stands of varying biomass. The surface measurements included soil moisture measurements in several stands. The soil moisture was low during the July flight and highest in November after heavy rains had occurred. The microwave images clearly distinguished between the different forest stands. Stand age, obtained from International Paper Corporation which owns the stands, showed a strong correlation between brightness temperature and stand age. This agrees with previous simulation studies of conifer forests which show that the brightness temperature increases with increasing stand biomass. Research is continuing to seek a quantitative correlation between the observed brightness temperature of the stands and their biomass and surface soil moisture.

  1. Tipping point of a conifer forest ecosystem under severe drought

    NASA Astrophysics Data System (ADS)

    Huang, Kaicheng; Yi, Chuixiang; Wu, Donghai; Zhou, Tao; Zhao, Xiang; Blanford, William J.; Wei, Suhua; Wu, Hao; Ling, Du; Li, Zheng

    2015-02-01

    Drought-induced tree mortality has recently received considerable attention. Questions have arisen over the necessary intensity and duration thresholds of droughts that are sufficient to trigger rapid forest declines. The values of such tipping points leading to forest declines due to drought are presently unknown. In this study, we have evaluated the potential relationship between the level of tree growth and concurrent drought conditions with data of the tree growth-related ring width index (RWI) of the two dominant conifer species (Pinus edulis and Pinus ponderosa) in the Southwestern United States (SWUS) and the meteorological drought-related standardized precipitation evapotranspiration index (SPEI). In this effort, we determined the binned averages of RWI and the 11 month SPEI within the month of July within each bin of 30 of RWI in the range of 0-3000. We found a significant correlation between the binned averages of RWI and SPEI at the regional-scale under dryer conditions. The tipping point of forest declines to drought is predicted by the regression model as SPEItp = -1.64 and RWItp = 0, that is, persistence of the water deficit (11 month) with intensity of -1.64 leading to negligible growth for the conifer species. When climate conditions are wetter, the correlation between the binned averages of RWI and SPEI is weaker which we believe is most likely due to soil water and atmospheric moisture levels no longer being the dominant factor limiting tree growth. We also illustrate a potential application of the derived tipping point (SPEItp = -1.64) through an examination of the 2002 extreme drought event in the SWUS conifer forest regions. Distinguished differences in remote-sensing based NDVI anomalies were found between the two regions partitioned by the derived tipping point.

  2. A white spruce gene catalog for conifer genome analyses.

    PubMed

    Rigault, Philippe; Boyle, Brian; Lepage, Pierre; Cooke, Janice E K; Bousquet, Jean; MacKay, John J

    2011-09-01

    Several angiosperm plant genomes, including Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), poplar (Populus trichocarpa), and grapevine (Vitis vinifera), have been sequenced, but the lack of reference genomes in gymnosperm phyla reduces our understanding of plant evolution and restricts the potential impacts of genomics research. A gene catalog was developed for the conifer tree Picea glauca (white spruce) through large-scale expressed sequence tag sequencing and full-length cDNA sequencing to facilitate genome characterizations, comparative genomics, and gene mapping. The resource incorporates new and publicly available sequences into 27,720 cDNA clusters, 23,589 of which are represented by full-length insert cDNAs. Expressed sequence tags, mate-pair cDNA clone analysis, and custom sequencing were integrated through an iterative process to improve the accuracy of clustering outcomes. The entire catalog spans 30 Mb of unique transcribed sequence. We estimated that the P. glauca nuclear genome contains up to 32,520 transcribed genes owing to incomplete, partially sequenced, and unsampled transcripts and that its transcriptome could span up to 47 Mb. These estimates are in the same range as the Arabidopsis and rice transcriptomes. Next-generation methods confirmed and enhanced the catalog by providing deeper coverage for rare transcripts, by extending many incomplete clusters, and by augmenting the overall transcriptome coverage to 38 Mb of unique sequence. Genomic sample sequencing at 8.5% of the 19.8-Gb P. glauca genome identified 1,495 clusters representing highly repeated sequences among the cDNA clusters. With a conifer transcriptome in full view, functional and protein domain annotations clearly highlighted the divergences between conifers and angiosperms, likely reflecting their respective evolutionary paths.

  3. Simulated and empiric wind pollination patterns of conifer ovulate cones

    PubMed Central

    Niklas, Karl J.

    1982-01-01

    Wind tunnel analyses of conifer ovulate cones indicate that the total geometry of the cone enhances the probability of pollen entrapment. Aerodynamic characteristics of cone scale-bract complexes are such that suspended pollen is directed toward the micropyles of attached ovules. Within the taxa examined, there appears to be a preferential entrapment by ovulate cones of pollen of the same species. The data are interpreted as evidence for an aerodynamic reciprocity between wind-suspended pollen and the structure of ovulate cones which increases the frequency of pollination and the potential for fertilization. Images PMID:16593147

  4. Bioactive Secondary Metabolites Produced by the Fungal Endophytes of Conifers.

    PubMed

    Stierle, Andrea A; Stierle, Donald B

    2015-10-01

    This is a review of bioactive secondary metabolites isolated from conifer-associated endophytic fungi from 1990-2014. This includes compounds with antimicrobial, anti-inflammatory, anti-proliferative and cytotoxic activity towards human cancer cell lines, and activity against either plant pathogens or plant insect pests. Compounds that were originally reported without associated activity were included if other studies ascribed activity to these compounds. Compounds were not included if they were exclusively phytotoxic or if they were isolated from active extracts but were not determined to be the active component of that extract. PMID:26669101

  5. Explaining the distribution of breeding and dispersal syndromes in conifers.

    PubMed

    Leslie, Andrew B; Beaulieu, Jeremy M; Crane, Peter R; Donoghue, Michael J

    2013-11-01

    The evolution of plants exhibiting different sexes, or dioecy, is correlated with a number of ecological and life-history traits such as woody growth form and animal-dispersed seeds, but the underlying causes of these associations are unclear. Previous work in seed plants has suggested that the evolution of fleshy cones or seeds may favour dioecy. In this study, we use a well-sampled molecular phylogeny of conifers to show that although dioecy and fleshiness strongly co-occur at the species level, this relationship has not resulted from numerous separate origins of this trait combination or from differential rates of diversification. Instead, we suggest that two character combinations-the ancestral dry-monoecious condition and the derived fleshy-dioecious condition-have persisted in conifers longer than other combinations over evolutionary time. The persistence of these trait combinations appears to reflect differences in the rate of successful transition into and out of these character states over time, as well as the geographical restriction of species with rare combinations and their consequent vulnerability to extinction. In general, we argue that such persistence explanations should be considered alongside 'key innovation' hypotheses in explaining the phylogenetic distribution of traits.

  6. Integration and macroevolutionary patterns in the pollination biology of conifers.

    PubMed

    Leslie, Andrew B; Beaulieu, Jeremy M; Crane, Peter R; Knopf, Patrick; Donoghue, Michael J

    2015-06-01

    Integration influences patterns of trait evolution, but the relationship between these patterns and the degree of trait integration is not well understood. To explore this further, we study a specialized pollination mechanism in conifers whose traits are linked through function but not development. This mechanism depends on interactions among three characters: pollen that is buoyant, ovules that face downward at pollination, and the production of a liquid droplet that buoyant grains float through to enter the ovule. We use a well-sampled phylogeny of conifers to test correlated evolution among these characters and specific sequences of character change. Using likelihood models of character evolution, we find that pollen morphology and ovule characters evolve in a concerted manner, where the flotation mechanism breaks down irreversibly following changes in orientation or drop production. The breakdown of this functional constraint, which may be facilitated by the lack of developmental integration among the constituent traits, is associated with increased trait variation and more diverse pollination strategies. Although this functional "release" increases diversity in some ways, the irreversible way in which the flotation mechanism is lost may eventually result in its complete disappearance from seed plant reproductive biology.

  7. Explaining the distribution of breeding and dispersal syndromes in conifers

    PubMed Central

    Leslie, Andrew B.; Beaulieu, Jeremy M.; Crane, Peter R.; Donoghue, Michael J.

    2013-01-01

    The evolution of plants exhibiting different sexes, or dioecy, is correlated with a number of ecological and life-history traits such as woody growth form and animal-dispersed seeds, but the underlying causes of these associations are unclear. Previous work in seed plants has suggested that the evolution of fleshy cones or seeds may favour dioecy. In this study, we use a well-sampled molecular phylogeny of conifers to show that although dioecy and fleshiness strongly co-occur at the species level, this relationship has not resulted from numerous separate origins of this trait combination or from differential rates of diversification. Instead, we suggest that two character combinations—the ancestral dry-monoecious condition and the derived fleshy-dioecious condition—have persisted in conifers longer than other combinations over evolutionary time. The persistence of these trait combinations appears to reflect differences in the rate of successful transition into and out of these character states over time, as well as the geographical restriction of species with rare combinations and their consequent vulnerability to extinction. In general, we argue that such persistence explanations should be considered alongside ‘key innovation’ hypotheses in explaining the phylogenetic distribution of traits. PMID:24026822

  8. Corrosion properties of electroplated CoNiFe films

    SciTech Connect

    Saito, M.; Yamada, K.; Ohashi, K.; Yasue, Y.; Sogawa, Y.; Osaka, T.

    1999-08-01

    Electroplated CoNiFe films with a saturation flux density as high as 2.1 T are potentially useful in high-density magnetic recording heads. The authors found that films electroplated at a high current density (15 mA/cm{sup 2}) from a bath without saccharin have a sufficient anodic pitting-corrosion potential ({minus}65 mV). The authors also found that the pitting-corrosion potential of films electroplated under a low current density (5 mA/cm{sup 2}) from saccharin-free baths have anodic pitting-corrosion potentials of less than {minus}300 mV. However, the corrosion resistance improved after annealing at temperatures above 100 C. The crystal-grain boundaries in the as-plated film that electroplated under a low current density from saccharin-free baths are not clear (i.e., that the phase is amorphous). But the crystal grain boundaries in the annealed film are clear. Films electroplated from baths containing saccharin also have anodic pitting-corrosion potentials of less than {minus}300 mV. Their corrosion resistance did not improve when they were annealed at 250 C. The deterioration of the corrosion resistance is attributed to the defects that increase the face-centered cubic (111) lattice constant. One of the most important characteristics of a highly corrosion-resistant CoNiFe film is fine crystal structure with very few defects.

  9. Kinetics of tracheid development explain conifer tree-ring structure.

    PubMed

    Cuny, Henri E; Rathgeber, Cyrille B K; Frank, David; Fonti, Patrick; Fournier, Meriem

    2014-09-01

    Conifer tree rings are generally composed of large, thin-walled cells of light earlywood followed by narrow, thick-walled cells of dense latewood. Yet, how wood formation processes and the associated kinetics create this typical pattern remains poorly understood. We monitored tree-ring formation weekly over 3 yr in 45 trees of three conifer species in France. Data were used to model cell development kinetics, and to attribute the relative importance of the duration and rate of cell enlargement and cell wall deposition on tree-ring structure. Cell enlargement duration contributed to 75% of changes in cell diameter along the tree rings. Remarkably, the amount of wall material per cell was quite constant along the rings. Consequently, and in contrast with widespread belief, changes in cell wall thickness were not principally attributed to the duration and rate of wall deposition (33%), but rather to the changes in cell size (67%). Cell enlargement duration, as the main driver of cell size and wall thickness, contributed to 56% of wood density variation along the rings. This mechanistic framework now forms the basis for unraveling how environmental stresses trigger deviations (e.g. false rings) from the normal tree-ring structure.

  10. Quantifying the consequences of conifer succession in aspen stands: decline in a biodiversity-supporting community.

    PubMed

    McCullough, S A; O'Geen, A T; Whiting, M L; Sarr, D A; Tate, K W

    2013-07-01

    Quaking aspen (Populus tremuloides Michaux) stands are important for biodiversity in conifer-dominated forest landscapes. Our goal was to quantify the consequences of conifer succession on understory diversity and litter quality, as well as associated changes in aspen stand condition. We studied aspen stands on national park land in the transition zone between the northern Sierra Nevada and southern Cascade mountain ranges. We field-measured ten metrics of aspen stand condition in 29 aspen stands. Along a gradient of increasing current conifer cover, we observed decreases in herbaceous species diversity and richness and an increase in forest floor O horizon depth. We interpreted aerial photos from 1952 and 1998 to determine whether directional changes in conifer cover had occurred in the stands over the past half century, and used regression modeling to associate succession with the observed range of aspen stand condition. From the period 1952 to 1998, we found that conifer encroachment occurred in half the sampled stands, with an average increase in conifer cover of 1% a year. Aspen were persistent in the remaining stands. Stand cover dynamics and percent total canopy cover interacted to influence species richness, diversity, aspen sprouting, and litter quality. In stands with conifer encroachment, both understory species richness and diversity declined. Although aspen sprouting increased, aspen establishment declined and the relative mass of woody to fine soil litter increased.

  11. Quantifying the consequences of conifer succession in aspen stands: decline in a biodiversity-supporting community.

    PubMed

    McCullough, S A; O'Geen, A T; Whiting, M L; Sarr, D A; Tate, K W

    2013-07-01

    Quaking aspen (Populus tremuloides Michaux) stands are important for biodiversity in conifer-dominated forest landscapes. Our goal was to quantify the consequences of conifer succession on understory diversity and litter quality, as well as associated changes in aspen stand condition. We studied aspen stands on national park land in the transition zone between the northern Sierra Nevada and southern Cascade mountain ranges. We field-measured ten metrics of aspen stand condition in 29 aspen stands. Along a gradient of increasing current conifer cover, we observed decreases in herbaceous species diversity and richness and an increase in forest floor O horizon depth. We interpreted aerial photos from 1952 and 1998 to determine whether directional changes in conifer cover had occurred in the stands over the past half century, and used regression modeling to associate succession with the observed range of aspen stand condition. From the period 1952 to 1998, we found that conifer encroachment occurred in half the sampled stands, with an average increase in conifer cover of 1% a year. Aspen were persistent in the remaining stands. Stand cover dynamics and percent total canopy cover interacted to influence species richness, diversity, aspen sprouting, and litter quality. In stands with conifer encroachment, both understory species richness and diversity declined. Although aspen sprouting increased, aspen establishment declined and the relative mass of woody to fine soil litter increased. PMID:23093369

  12. Sequenced genomes and rapidly emerging technologies pave the way for conifer evolutionary developmental biology.

    PubMed

    Uddenberg, Daniel; Akhter, Shirin; Ramachandran, Prashanth; Sundström, Jens F; Carlsbecker, Annelie

    2015-01-01

    Conifers, Ginkgo, cycads and gnetophytes comprise the four groups of extant gymnosperms holding a unique position of sharing common ancestry with the angiosperms. Comparative studies of gymnosperms and angiosperms are the key to a better understanding of ancient seed plant morphologies, how they have shifted over evolution to shape modern day species, and how the genes governing these morphologies have evolved. However, conifers and other gymnosperms have been notoriously difficult to study due to their long generation times, inaccessibility to genetic experimentation and unavailable genome sequences. Now, with three draft genomes from spruces and pines, rapid advances in next generation sequencing methods for genome wide expression analyses, and enhanced methods for genetic transformation, we are much better equipped to address a number of key evolutionary questions relating to seed plant evolution. In this mini-review we highlight recent progress in conifer developmental biology relevant to evo-devo questions. We discuss how genome sequence data and novel techniques might allow us to explore genetic variation and naturally occurring conifer mutants, approaches to reduce long generation times to allow for genetic studies in conifers, and other potential upcoming research avenues utilizing current and emergent techniques. Results from developmental studies of conifers and other gymnosperms in comparison to those in angiosperms will provide information to trace core molecular developmental control tool kits of ancestral seed plants, but foremost they will greatly improve our understanding of the biology of conifers and other gymnosperms in their own right. PMID:26579190

  13. Sequenced genomes and rapidly emerging technologies pave the way for conifer evolutionary developmental biology

    PubMed Central

    Uddenberg, Daniel; Akhter, Shirin; Ramachandran, Prashanth; Sundström, Jens F.; Carlsbecker, Annelie

    2015-01-01

    Conifers, Ginkgo, cycads and gnetophytes comprise the four groups of extant gymnosperms holding a unique position of sharing common ancestry with the angiosperms. Comparative studies of gymnosperms and angiosperms are the key to a better understanding of ancient seed plant morphologies, how they have shifted over evolution to shape modern day species, and how the genes governing these morphologies have evolved. However, conifers and other gymnosperms have been notoriously difficult to study due to their long generation times, inaccessibility to genetic experimentation and unavailable genome sequences. Now, with three draft genomes from spruces and pines, rapid advances in next generation sequencing methods for genome wide expression analyses, and enhanced methods for genetic transformation, we are much better equipped to address a number of key evolutionary questions relating to seed plant evolution. In this mini-review we highlight recent progress in conifer developmental biology relevant to evo-devo questions. We discuss how genome sequence data and novel techniques might allow us to explore genetic variation and naturally occurring conifer mutants, approaches to reduce long generation times to allow for genetic studies in conifers, and other potential upcoming research avenues utilizing current and emergent techniques. Results from developmental studies of conifers and other gymnosperms in comparison to those in angiosperms will provide information to trace core molecular developmental control tool kits of ancestral seed plants, but foremost they will greatly improve our understanding of the biology of conifers and other gymnosperms in their own right. PMID:26579190

  14. Sequenced genomes and rapidly emerging technologies pave the way for conifer evolutionary developmental biology.

    PubMed

    Uddenberg, Daniel; Akhter, Shirin; Ramachandran, Prashanth; Sundström, Jens F; Carlsbecker, Annelie

    2015-01-01

    Conifers, Ginkgo, cycads and gnetophytes comprise the four groups of extant gymnosperms holding a unique position of sharing common ancestry with the angiosperms. Comparative studies of gymnosperms and angiosperms are the key to a better understanding of ancient seed plant morphologies, how they have shifted over evolution to shape modern day species, and how the genes governing these morphologies have evolved. However, conifers and other gymnosperms have been notoriously difficult to study due to their long generation times, inaccessibility to genetic experimentation and unavailable genome sequences. Now, with three draft genomes from spruces and pines, rapid advances in next generation sequencing methods for genome wide expression analyses, and enhanced methods for genetic transformation, we are much better equipped to address a number of key evolutionary questions relating to seed plant evolution. In this mini-review we highlight recent progress in conifer developmental biology relevant to evo-devo questions. We discuss how genome sequence data and novel techniques might allow us to explore genetic variation and naturally occurring conifer mutants, approaches to reduce long generation times to allow for genetic studies in conifers, and other potential upcoming research avenues utilizing current and emergent techniques. Results from developmental studies of conifers and other gymnosperms in comparison to those in angiosperms will provide information to trace core molecular developmental control tool kits of ancestral seed plants, but foremost they will greatly improve our understanding of the biology of conifers and other gymnosperms in their own right.

  15. Low Elevation Riparian Environments: Warm-Climate Refugia for Conifers in the Great Basin, USA?

    NASA Astrophysics Data System (ADS)

    Millar, C.; Charlet, D. A.; Westfall, R. D.; Delany, D.

    2015-12-01

    The Great Basin, USA, contains hundreds of small to large mountain ranges. Many reach alpine elevations, which are separated from each other by low-elevation basins currently inhospitable to conifer growth. Many of these ranges support montane and subalpine conifer species that have affinities to the Sierra Nevada or Rocky Mountains, and from which these conifers migrated during cool periods of the Pleistocene. Under Holocene climates, the Great Basin geography became a terrestrial island-archipelago, wherein conifer populations are isolated among ranges, and inter-range migration is highly limited. During warm intervals of the Holocene, conifers would be expected to have migrated upslope following favorable conditions, and extirpation would be assumed to result from continued warming. Independent patterns, repeating across multiple species' distributions, however, suggest that refugia were present in these ranges during warm periods, and that low elevation environments below the current main distributions acted as climatic refugia. We hypothesize that cool, narrow, and north-aspect ravines, which during cool climates support persistent or seasonal creeks and deciduous riparian communities, become available as conifer habitat when warming climates desiccate creeks and deplete riparian species. We further speculate that cold-air drainage, reduced solar insolation, lower wind exposure, and higher water tables in these topographic positions support populations of montane and subalpine conifers even during warm climate intervals when high elevations are unfavorable for conifer persistence. On return to cool climates, low elevation refugia become sources for recolonizing higher slopes, and/or continue to persist as relictual populations. We present several lines of evidence supporting this hypothesis, and speculate that low-elevation, extramarginal riparian environments might act as climate refugia for Great Basin conifers in the future as well.

  16. Anaerobic activities of bacteria and fungi in moderately acidic conifer and deciduous leaf litter.

    PubMed

    Reith, Frank; Drake, Harold L; Küsel, Kirsten

    2002-07-01

    Abstract The litter layer of forest soils harbors high amounts of labile organic matter, and anaerobic decomposition processes can be initiated when oxygen is consumed more rapidly than it is supplied by diffusion. In this study, two adjacent moderately acidic forest sites, a spruce and a beech-oak forest, were selected to compare the anaerobic bacterial and fungal activities and populations of conifer and deciduous leaf litter. Most probable number (MPN) estimates of general heterotrophic aerobes and anaerobes from conifer litter equaled those from deciduous leaf litter. H(2), ethanol, formate, and lactate were initially produced with similar rates in both anoxic conifer and deciduous leaf litter microcosms. These products were rapidly consumed in deciduous leaf but not in conifer litter microcosms. Supplemental ethanol and H(2) were consumed only by deciduous leaf litter and yielded additional amounts of acetate in stoichiometries indicative of ethanol- or H(2)-dependent acetogenesis. The negligible turnover of primary fermentation products in conifer litter might be due to the low numbers of acetogens and secondary fermenters present in conifer litter compared to deciduous leaf litter. Fungi capable of anaerobic growth made up only 0.01-0.1% of the total anaerobic microorganisms cultured from conifer and deciduous leaf litter, respectively. Metabolic product profiles obtained from the highest anoxic, growth-positive MPN dilutions supplemented with antibacterial agents indicated that the dominant population of fungi, apparently mainly yeast-like cells, produced H(2), ethanol, acetate, and lactate both in conifer and deciduous leaf litter. Thus, despite acidic conditions, bacteria appear to dominate in the decomposition of carbon in anoxic microsites of both conifer and deciduous leaf litter.

  17. Cyclic voltammetric study of Co-Ni-Fe alloys electrodeposition in sulfate medium

    SciTech Connect

    Hanafi, I.; Daud, A. R.; Radiman, S.

    2013-11-27

    Electrochemical technique has been used to study the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy on indium tin oxide (ITO) coated glass substrate. To obtain the nucleation mechanism, cyclic voltammetry is used to characterize the Co-Ni-Fe system. The scanning rate effect on the deposition process was investigated. Deposition of single metal occurs at potential values more positive than that estimated stability potential. Based on the cyclic voltammetry results, the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy clearly show that the process of diffusion occurs is controlled by the typical nucleation mechanism.

  18. Evidence of Intense Chromosomal Shuffling during Conifer Evolution

    PubMed Central

    de Miguel, Marina; Bartholomé, Jérôme; Ehrenmann, François; Murat, Florent; Moriguchi, Yoshinari; Uchiyama, Kentaro; Ueno, Saneyoshi; Tsumura, Yoshihiko; Lagraulet, Hélène; de Maria, Nuria; Cabezas, José-Antonio; Cervera, María-Teresa; Gion, Jean Marc; Salse, Jérôme; Plomion, Christophe

    2015-01-01

    Although recent advances have been gained on genome evolution in angiosperm lineages, virtually nothing is known about karyotype evolution in the other group of seed plants, the gymnosperms. Here, we used high-density gene-based linkage mapping to compare the karyotype structure of two families of conifers (the most abundant group of gymnosperms) separated around 290 Ma: Pinaceae and Cupressaceae. We propose for the first time a model based on the fusion of 20 ancestral chromosomal blocks that may have shaped the modern karyotpes of Pinaceae (with n = 12) and Cupressaceae (with n = 11). The considerable difference in modern genome organization between these two lineages contrasts strongly with the remarkable level of synteny already reported within the Pinaceae. It also suggests a convergent evolutionary mechanism of chromosomal block shuffling that has shaped the genomes of the spermatophytes. PMID:26400405

  19. Controls over hydrocarbon emissions from boreal forest conifers

    SciTech Connect

    Lerdau, M.; Litvak, M.; Monson, R. |

    1995-06-01

    The emissions of monoterpenes and isoprene were measured from two species of conifers native to the boreal forest of Canada, jack pine, Pinus rigida, and black spruce, Picea Mariana. We examined the effects of phenology and needle age on the emissions of these compounds, and the variations in tissue concentrations of monoterpenes. We measured photosynthetic carbon uptake and hydrocarbon emissions at two sites in northern Saskatchewan under controlled light, temperatures, and CO{sub 2} concentrations, and analyzed carbon uptake rates using an infra-red gas analyzer and hydrocarbon emissions using a solid sorbent/thermal desorption system coupled to a gas chromatograph with a mass spectrometer. Our data indicate a strong effect of temperature and seasonality on emissions but only small effects of site conditions. These results suggest that regional models of hydrocarbon emissions from boreal forests should focus on temperature and phenology as the most important controlling variables.

  20. In-vitro Antimicrobial Activities of Some Iranian Conifers

    PubMed Central

    Afsharzadeh, Maryam; Naderinasab, Mahboobe; Tayarani Najaran, Zahra; Barzin, Mohammad; Emami, Seyed Ahmad

    2013-01-01

    Male and female leaves and fruits of eleven different taxons of Iranian conifers (Cupressus sempervirens var. horizontalis, C. sempervirens var. sempervirens, C. sempervirens cv. Cereifeormis, Juniperus communis subsp. hemisphaerica, J. excelsa subsp. excelsa, J. excelsa subsp. polycarpos, J. foetidissima, J. oblonga, J. sabina, Platycladus orientalis and Taxus baccata) were collected from different localities of Iran, dried and extracted with methanol. The extracts were tested for their antimicrobial activity against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Candida albicans. The extracts were screened qualitatively using four different methods, the disc diffusion, hole plate, cylinder agar diffusion and agar dilution methods, whereas the minimum inhibitory concentrations (MIC) of each extract were determined by the agar dilution method. The best result was obtained by means of hole plate method in qualitative determination of antimicrobial activities of extracts and the greatest activity was found against S. aureus in all tested methods. PMID:24250573

  1. Uniform versus asymmetric shading mediates crown recession in conifers.

    PubMed

    Schoonmaker, Amanda L; Lieffers, Victor J; Landhäusser, Simon M

    2014-01-01

    In this study we explore the impact of asymmetrical vs. uniform crown shading on the mortality and growth of upper and lower branches within tree crowns, for two conifer species: shade intolerant lodgepole pine (Pinus contorta) and shade tolerant white spruce (Picea glauca). We also explore xylem hydraulics, foliar nutrition, and carbohydrate status as drivers for growth and expansion of the lower and upper branches in various types of shading. This study was conducted over a two-year period across 10 regenerating forest sites dominated by lodgepole pine and white spruce, in the lower foothills of Alberta, Canada. Trees were assigned to one of four shading treatments: (1), complete uniform shading of the entire tree, (2) light asymmetric shading where the lower 1/4-1/3 of the tree crown was shaded, (3) heavy asymmetric shading as in (2) except with greater light reduction and (4) control in which no artificial shading occurred and most of the entire crown was exposed to full light. Asymmetrical shading of only the lower crown had a larger negative impact on the bud expansion and growth than did uniform shading, and the effect was stronger in pine relative to spruce. In addition, lower branches in pine also had lower carbon reserves, and reduced xylem-area specific conductivity compared to spruce. For both species, but particularly the pine, the needles of lower branches tended to store less C than upper branches in the asymmetric shade, which could suggest a movement of reserves away from the lower branches. The implications of these findings correspond with the inherent shade tolerance and self-pruning behavior of these conifers and supports a carbon based mechanism for branch mortality--mediated by an asymmetry in light exposure of the crown. PMID:25136823

  2. Uniform versus asymmetric shading mediates crown recession in conifers.

    PubMed

    Schoonmaker, Amanda L; Lieffers, Victor J; Landhäusser, Simon M

    2014-01-01

    In this study we explore the impact of asymmetrical vs. uniform crown shading on the mortality and growth of upper and lower branches within tree crowns, for two conifer species: shade intolerant lodgepole pine (Pinus contorta) and shade tolerant white spruce (Picea glauca). We also explore xylem hydraulics, foliar nutrition, and carbohydrate status as drivers for growth and expansion of the lower and upper branches in various types of shading. This study was conducted over a two-year period across 10 regenerating forest sites dominated by lodgepole pine and white spruce, in the lower foothills of Alberta, Canada. Trees were assigned to one of four shading treatments: (1), complete uniform shading of the entire tree, (2) light asymmetric shading where the lower 1/4-1/3 of the tree crown was shaded, (3) heavy asymmetric shading as in (2) except with greater light reduction and (4) control in which no artificial shading occurred and most of the entire crown was exposed to full light. Asymmetrical shading of only the lower crown had a larger negative impact on the bud expansion and growth than did uniform shading, and the effect was stronger in pine relative to spruce. In addition, lower branches in pine also had lower carbon reserves, and reduced xylem-area specific conductivity compared to spruce. For both species, but particularly the pine, the needles of lower branches tended to store less C than upper branches in the asymmetric shade, which could suggest a movement of reserves away from the lower branches. The implications of these findings correspond with the inherent shade tolerance and self-pruning behavior of these conifers and supports a carbon based mechanism for branch mortality--mediated by an asymmetry in light exposure of the crown.

  3. Uniform versus Asymmetric Shading Mediates Crown Recession in Conifers

    PubMed Central

    Schoonmaker, Amanda L.; Lieffers, Victor J.; Landhäusser, Simon M.

    2014-01-01

    In this study we explore the impact of asymmetrical vs. uniform crown shading on the mortality and growth of upper and lower branches within tree crowns, for two conifer species: shade intolerant lodgepole pine (Pinus contorta) and shade tolerant white spruce (Picea glauca). We also explore xylem hydraulics, foliar nutrition, and carbohydrate status as drivers for growth and expansion of the lower and upper branches in various types of shading. This study was conducted over a two-year period across 10 regenerating forest sites dominated by lodgepole pine and white spruce, in the lower foothills of Alberta, Canada. Trees were assigned to one of four shading treatments: (1), complete uniform shading of the entire tree, (2) light asymmetric shading where the lower 1/4–1/3 of the tree crown was shaded, (3) heavy asymmetric shading as in (2) except with greater light reduction and (4) control in which no artificial shading occurred and most of the entire crown was exposed to full light. Asymmetrical shading of only the lower crown had a larger negative impact on the bud expansion and growth than did uniform shading, and the effect was stronger in pine relative to spruce. In addition, lower branches in pine also had lower carbon reserves, and reduced xylem-area specific conductivity compared to spruce. For both species, but particularly the pine, the needles of lower branches tended to store less C than upper branches in the asymmetric shade, which could suggest a movement of reserves away from the lower branches. The implications of these findings correspond with the inherent shade tolerance and self-pruning behavior of these conifers and supports a carbon based mechanism for branch mortality – mediated by an asymmetry in light exposure of the crown. PMID:25136823

  4. Morphological and functional stasis in mycorrhizal root nodules as exhibited by a Triassic conifer.

    PubMed

    Schwendemann, Andrew B; Decombeix, Anne-Laure; Taylor, Thomas N; Taylor, Edith L; Krings, Michael

    2011-08-16

    Mycorrhizal root nodules occur in the conifer families Araucariaceae, Podocarpaceae, and Sciadopityaceae. Although the fossil record of these families can be traced back into the early Mesozoic, the oldest fossil evidence of root nodules previously came from the Cretaceous. Here we report on cellularly preserved root nodules of the early conifer Notophytum from Middle Triassic permineralized peat of Antarctica. These fossil root nodules contain fungal arbuscules, hyphal coils, and vesicles in their cortex. Numerous glomoid-type spores are found in the peat matrix surrounding the nodules. This discovery indicates that mutualistic associations between conifer root nodules and arbuscular mycorrhizal fungi date back to at least the early Mesozoic, the period during which most of the modern conifer families first appeared. Notophytum root nodules predate the next known appearance of this association by 100 million years, indicating that this specialized form of mycorrhizal symbiosis has ancient origins.

  5. Morphological and functional stasis in mycorrhizal root nodules as exhibited by a Triassic conifer

    PubMed Central

    Schwendemann, Andrew B.; Decombeix, Anne-Laure; Taylor, Thomas N.; Krings, Michael

    2011-01-01

    Mycorrhizal root nodules occur in the conifer families Araucariaceae, Podocarpaceae, and Sciadopityaceae. Although the fossil record of these families can be traced back into the early Mesozoic, the oldest fossil evidence of root nodules previously came from the Cretaceous. Here we report on cellularly preserved root nodules of the early conifer Notophytum from Middle Triassic permineralized peat of Antarctica. These fossil root nodules contain fungal arbuscules, hyphal coils, and vesicles in their cortex. Numerous glomoid-type spores are found in the peat matrix surrounding the nodules. This discovery indicates that mutualistic associations between conifer root nodules and arbuscular mycorrhizal fungi date back to at least the early Mesozoic, the period during which most of the modern conifer families first appeared. Notophytum root nodules predate the next known appearance of this association by 100 million years, indicating that this specialized form of mycorrhizal symbiosis has ancient origins. PMID:21808011

  6. Biomass in conifer plantations of northeastern Minnesota. Forest Service research paper

    SciTech Connect

    Ohmann, L.F.

    1985-10-01

    The report provides biomass estimates for vegetative strata and herb-low shrub species for 53 conifer plantations in NE Minnesota. The estimates are analyzed by plantation age and silvicultural practices used to establish and release the plantations.

  7. Morphological and functional stasis in mycorrhizal root nodules as exhibited by a Triassic conifer.

    PubMed

    Schwendemann, Andrew B; Decombeix, Anne-Laure; Taylor, Thomas N; Taylor, Edith L; Krings, Michael

    2011-08-16

    Mycorrhizal root nodules occur in the conifer families Araucariaceae, Podocarpaceae, and Sciadopityaceae. Although the fossil record of these families can be traced back into the early Mesozoic, the oldest fossil evidence of root nodules previously came from the Cretaceous. Here we report on cellularly preserved root nodules of the early conifer Notophytum from Middle Triassic permineralized peat of Antarctica. These fossil root nodules contain fungal arbuscules, hyphal coils, and vesicles in their cortex. Numerous glomoid-type spores are found in the peat matrix surrounding the nodules. This discovery indicates that mutualistic associations between conifer root nodules and arbuscular mycorrhizal fungi date back to at least the early Mesozoic, the period during which most of the modern conifer families first appeared. Notophytum root nodules predate the next known appearance of this association by 100 million years, indicating that this specialized form of mycorrhizal symbiosis has ancient origins. PMID:21808011

  8. Ungulate exclusion, conifer thinning and mule deer forage in northeastern New Mexico

    USGS Publications Warehouse

    Kramer, David W.; Sorensen, Grant E.; Taylor, Chase A.; Cox, Robert D.; Gipson, Philip S.; Cain, James W.

    2015-01-01

    The southwestern United States has experienced expansion of conifer species (Juniperus spp. and Pinus ponderosa) into areas of semi-arid grassland over the past century. The expansion of conifers can limit palatable forage and reduce grass and forb communities. Conifer species are sometimes thinned through hydraulic mulching or selective cutting. We assessed the effects of these treatments on mule deer (Odocoileus hemionus) habitat in northeastern New Mexico to determine if conifer thinning improved cover of preferred forage species for mule deer in areas with and without ungulates. We measured plant cover and occurrence of preferred forage species in the summers of 2011 and 2012. An ongoing regional drought probably reduced vegetation response, with preferred forage species and herbaceous cover responding to conifer thinning or ungulate exclusion immediately following treatment, but not the following year. In 2011, areas that received thinning treatments had a higher abundance of preferred forage when compared to sites with no treatment. Grass coverage exhibited an immediate response in 2011, with ungulate exclosures containing 8% more coverage than areas without exclosures. The results suggest that conifer thinning and ungulate exclusion may elicit a positive response, however in the presence of drought; the positive effects are only short-term.

  9. Evolutionary assembly of the conifer fauna: distinguishing ancient from recent associations in bark beetles.

    PubMed Central

    Sequeira, A S; Normark, B B; Farrell, B D

    2000-01-01

    Several shifts from ancestral conifer feeding to angiosperm feeding have been implicated in the unparalleled diversification of beetle species. The single largest angiosperm-feeding beetle clade occurs in the weevils, and comprises the family Curculionidae and relatives. Most authorities confidently place the bark beetles (Scolytidae) within this radiation of angiosperm feeders. However, some clues indicate that the association between conifers and some scolytids, particularly in the tribe Tomicini, is a very ancient one. For instance, several fragments of Gondwanaland (South America, New Caledonia, Australia and New Guinea) harbour endemic Tomicini specialized on members of the formerly widespread and abundant conifer family Araucariaceae. As a first step towards resolving this seeming paradox, we present a phylogenetic analysis of the beetle family Scolytidae with particularly intensive sampling of conifer-feeding Tomicini and allies. We sequenced and analysed elongation factor 1alpha and nuclear rDNAs 18S and 28S for 45 taxa, using members of the weevil family Cossoninae as an out-group. Our results indicate that conifer feeding is the ancestral host association of scolytids, and that the most basal lineages of scolytids feed on Aramucaria. If scolytids are indeed nested within a great angiosperm-feeding clade, as many authorities have held, then a reversion to conifer feeding in ancestral scolytids appears to have occurred in the Mesozoic, when Araucaria still formed a major component of the woody flora. PMID:11133024

  10. Fluxes of trichloroacetic acid through a conifer forest canopy.

    PubMed

    Stidson, R T; Heal, K V; Dickey, C A; Cape, J N; Heal, M R

    2004-11-01

    Controlled-dosing experiments with conifer seedlings have demonstrated an above-ground route of uptake for trichloroacetic acid (TCA) from aqueous solution into the canopy, in addition to uptake from the soil. The aim of this work was to investigate the loss of TCA to the canopy in a mature conifer forest exposed only to environmental concentrations of TCA by analysing above- and below-canopy fluxes of TCA and within-canopy instantaneous reservoir of TCA. Concentrations and fluxes of TCA were quantified for one year in dry deposition, rainwater, cloudwater, throughfall, stemflow and litterfall in a 37-year-old Sitka spruce and larch plantation in SW Scotland. Above-canopy TCA deposition was dominated by rainfall (86%), compared with cloudwater (13%) and dry deposition (1%). On average only 66% of the TCA deposition passed through the canopy in throughfall and stemflow (95% and 5%, respectively), compared with 47% of the wet precipitation depth. Consequently, throughfall concentration of TCA was, on average, approximately 1.4 x rainwater concentration. There was no significant difference in below-canopy fluxes between Sitka spruce and larch, or at a forest-edge site. Annual TCA deposited from the canopy in litterfall was only approximately 1-2% of above-canopy deposition. On average, approximately 800 microg m(-2) of deposited TCA was lost to the canopy per year, compared with estimates of above-ground TCA storage of approximately 400 and approximately 300 microg m(-2) for Sitka spruce and larch, respectively. Taking into account likely uncertainties in these values ( approximately +/- 50%), these data yield an estimate for the half-life of within-canopy elimination of TCA in the range 50-200 days, assuming steady-state conditions and that all TCA lost to the canopy is transferred into the canopy material, rather than degraded externally. The observations provide strong indication that an above-ground route is important for uptake of TCA specifically of atmospheric

  11. Assessed Potential of Conifers as Proxy Paleo-wind Stations

    NASA Astrophysics Data System (ADS)

    Hamilton, W. L.

    2002-12-01

    A new method for extracting wind direction and velocity information from tree rings has been developed and applied to more than 60 conifers near two weather stations on the Olympic Peninsula of northwest Washington. Utilizing measurements from cores and full cross-sections, a mechanical wind-drag bending-moment model relates ring eccentricity to the horizontal component of unbalanced forces, principally wind, affecting the tree. Straight conifers on level ground typically develop thicker rings on the downwind side. The two study areas have very different wind patterns. At Port Angeles dominant wind is the westerly sea breeze, but at Quillayute dominant winds are southeast and southwest. Tested weather station record wind parameters include: annual (and seasonal) mean and summed velocity for hourly or peak daily observations. Sum velocity yields much higher significance than mean velocity in regressions against growth eccentricity, suggesting that tree response may be related to momentum transfer. Correlation significance increases when a 3-year running mean is applied to smooth out measurement error, delayed response to wind, and spatial wind variability; and when several trees are averaged, dispersing events such as limb loss. Linear regression of the vector resultants of eccentricity of Douglas-fir against annual sum velocity vector records at Port Angeles yields significant (P(t)<0.05) slope constants for R and θ in most cases. Vector assessment of Sitka spruce near Quillayute is limited by multimodal wind. Scalar sum velocity and ring-width eccentricity data from these and other species are significantly correlated at both areas. Seasonal assessment of eccentricity response to wind at the Pacific coast suggests that very high velocities, especially during growth season, promote thinner rings on the downwind side. In such cases predicted response is delayed by up to 8 years. Rainfall is a significant co-contributor to eccentricity only at the wetter coastal

  12. Measured and Predicted Solar Transmission Through Conifer Canopies

    NASA Astrophysics Data System (ADS)

    Hardy, J. P.; Marks, D.; Melloh, R.; Winstral, A.; Koenig, G.

    2003-12-01

    Snow dynamics under forest canopies are strongly influenced by the large spatial variability of energy transfers in this environment. Transmission of solar radiation through a canopy is highly variable and depends on tree species, as well as canopy properties such as height, density, and leaf area. Modeling snow processes at the stand scale has proven challenging due to the highly variable structure of forest canopies controlling solar radiation incident at the snow surface. This study aims to describe and simulate the solar irradiance variability on the snow surface beneath two stands: an open, discontinuous conifer canopy, and a relatively uniform conifer canopy. The objectives are 1) to compare measured and predicted solar transmissivities based on field data and analysis of hemispherical photographs and 2) to evaluate the magnitude of the predicted solar fluxes and the timing of snow ablation using the snow model, SNOBAL, driven separately with both measured and modeled solar transmissivities. Field measurements were made during winters of 2002 and 2003 at the Local Scale Observation Site (LSOS) in Fraser, Colorado USA as part of the Cold Land Processes Experiment. The canopy structure of the trees in a 0.8 ha plot was measured in detail (species, tree location, height, crown height, diameter at breast height). We measured incoming global solar radiation at the snow surface, beneath uniform and discontinuous lodgepole pine canopies, using arrays of 10 upward looking pyranometers at each site. Incoming global solar radiation was measured above the canopy and used to calculate transmitted values. Hemispherical photographs taken, with a Nikon CoolPix995 digital camera equipped with a Nikon Fisheye Converter (183° FOV), at each pyranometer location (n=20) were analyzed with Gap Light Analyzer (GLA) software (Frazer, et al. 1999) to determine total solar transmissivity. Mean measured and predicted solar transmissivities compared well (r2=0.86) in the discontinuous

  13. The Earliest Evidence of Holometabolan Insect Pupation in Conifer Wood

    PubMed Central

    Tapanila, Leif; Roberts, Eric M.

    2012-01-01

    Background The pre-Jurassic record of terrestrial wood borings is poorly resolved, despite body fossil evidence of insect diversification among xylophilic clades starting in the late Paleozoic. Detailed analysis of borings in petrified wood provides direct evidence of wood utilization by invertebrate animals, which typically comprises feeding behaviors. Methodology/Principal Findings We describe a U-shaped boring in petrified wood from the Late Triassic Chinle Formation of southern Utah that demonstrates a strong linkage between insect ontogeny and conifer wood resources. Xylokrypta durossi new ichnogenus and ichnospecies is a large excavation in wood that is backfilled with partially digested xylem, creating a secluded chamber. The tracemaker exited the chamber by way of a small vertical shaft. This sequence of behaviors is most consistent with the entrance of a larva followed by pupal quiescence and adult emergence — hallmarks of holometabolous insect ontogeny. Among the known body fossil record of Triassic insects, cupedid beetles (Coleoptera: Archostemata) are deemed the most plausible tracemakers of Xylokrypta, based on their body size and modern xylobiotic lifestyle. Conclusions/Significance This oldest record of pupation in fossil wood provides an alternative interpretation to borings once regarded as evidence for Triassic bees. Instead Xylokrypta suggests that early archostematan beetles were leaders in exploiting wood substrates well before modern clades of xylophages arose in the late Mesozoic. PMID:22355387

  14. Conifer flavonoid compounds inhibit detoxification enzymes and synergize insecticides.

    PubMed

    Wang, Zhiling; Zhao, Zhong; Cheng, Xiaofei; Liu, Suqi; Wei, Qin; Scott, Ian M

    2016-02-01

    Detoxification by glutathione S-transferases (GSTs) and esterases are important mechanisms associated with insecticide resistance. Discovery of novel GST and esterase inhibitors from phytochemicals could provide potential new insecticide synergists. Conifer tree species contain flavonoids, such as taxifolin, that inhibit in vitro GST activity. The objectives were to test the relative effectiveness of taxifolin as an enzyme inhibitor and as an insecticide synergist in combination with the organophosphorous insecticide, Guthion (50% azinphos-methyl), and the botanical insecticide, pyrethrum, using an insecticide-resistant Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say) strain. Both taxifolin and its isomer, quercetin, increased the mortality of 1(st) instar CPB larvae after 48h when combined with Guthion, but not pyrethrum. Taxifolin had greater in vitro esterase inhibition compared with the commonly used esterase inhibitor, S, S, S-tributyl phosphorotrithioate (DEF). An in vivo esterase and GST inhibition effect after ingestion of taxifolin was measured, however DEF caused a greater suppression of esterase activity. This study demonstrated that flavonoid compounds have both in vitro and in vivo esterase inhibition, which is likely responsible for the insecticide synergism observed in insecticide-resistant CPB. PMID:26821651

  15. Biosynthesis and Metabolic Fate of Phenylalanine in Conifers.

    PubMed

    Pascual, María B; El-Azaz, Jorge; de la Torre, Fernando N; Cañas, Rafael A; Avila, Concepción; Cánovas, Francisco M

    2016-01-01

    The amino acid phenylalanine (Phe) is a critical metabolic node that plays an essential role in the interconnection between primary and secondary metabolism in plants. Phe is used as a protein building block but it is also as a precursor for numerous plant compounds that are crucial for plant reproduction, growth, development, and defense against different types of stresses. The metabolism of Phe plays a central role in the channeling of carbon from photosynthesis to the biosynthesis of phenylpropanoids. The study of this metabolic pathway is particularly relevant in trees, which divert large amounts of carbon into the biosynthesis of Phe-derived compounds, particularly lignin, an important constituent of wood. The trunks of trees are metabolic sinks that consume a considerable percentage of carbon and energy from photosynthesis, and carbon is finally immobilized in wood. This paper reviews recent advances in the biosynthesis and metabolic utilization of Phe in conifer trees. Two alternative routes have been identified: the ancient phenylpyruvate pathway that is present in microorganisms, and the arogenate pathway that possibly evolved later during plant evolution. Additionally, an efficient nitrogen recycling mechanism is required to maintain sustained growth during xylem formation. The relevance of phenylalanine metabolic pathways in wood formation, the biotic interactions, and ultraviolet protection is discussed. The genetic manipulation and transcriptional regulation of the pathways are also outlined. PMID:27468292

  16. Advances in Conifer Somatic Embryogenesis Since Year 2000.

    PubMed

    Klimaszewska, Krystyna; Hargreaves, Catherine; Lelu-Walter, Marie-Anne; Trontin, Jean-François

    2016-01-01

    This review compiles research results published over the last 14 years on conifer somatic embryogenesis (SE). Emphasis is placed on the newest findings that affect the response of seed embryos (typical explants) and shoot primordia (rare explants) to the induction of SE and long-term culture of early somatic embryos. Much research in recent years has focused on maturation of somatic embryos, with respect to both yield and quality, as an important stage for the production of a large number of vigorous somatic seedlings. Attempts to scale up somatic embryo production numbers and handling have resulted in a few bioreactor designs, the utility of which may prove beneficial for an industrial application. A few simplified cryopreservation methods for embryonal masses (EM) were developed as a means to ensure cost-efficient long-term storage of genotypes during clonal field testing. Finally, recent long-term studies on the growth of somatic trees in the field, including seed production yield and comparison of seed parameters produced by somatic versus seed-derived trees, are described.

  17. Conservative water management in the widespread conifer genus Callitris

    PubMed Central

    Brodribb, Timothy J.; Bowman, David M. J. S.; Grierson, Pauline F.; Murphy, Brett P.; Nichols, Scott; Prior, Lynda D.

    2013-01-01

    Water management by woody species encompasses characters involved in seeking, transporting and evaporating water. Examples of adaptation of individual characters to water availability are common, but little is known about the adaptability of whole-plant water management. Here we use plant hydration and growth to examine variation in whole-plant water management characteristics within the conifer genus Callitris. Using four species that cover the environmental extremes in the Australian continent, we compare seasonal patterns of growth and hydration over 2 years to determine the extent to which species exhibit adaptive variation to the local environment. Detailed measurements of gas exchange in one species are used to produce a hydraulic model to predict changes in leaf water potential throughout the year. This same model, when applied to the remaining three species, provided a close representation of the measured patterns of water potential gradient at all sites, suggesting strong conservation in water management, a conclusion supported by carbon and oxygen isotope measurements in Callitris from across the continent. We conclude that despite its large range in terms of rainfall, Callitris has a conservative water management strategy, characterized by a high sensitivity of growth to rainfall and a delayed (anisohydric) closure of stomata during soil drying.

  18. Effects of acid fog and ozone on conifers. Final report

    SciTech Connect

    Bytnerowicz, A.; Olszyk, D.M.; Takemoto, B.K.; McCool, P.M.; Musselman, R.C.

    1989-05-01

    This study evaluated the effects of acidic fog (pH 2.0, 3.0, or 4.0) on the physiological, biochemical, and growth responses of two coniferous tree species (Pinus ponderosa and Abies concolor), and determined if exposure to acidic fog predisposed the tree seedlings to the phytotoxic effects of ozone (O{sub 3}). Results provide evidence that the growth and metabolic responses of two coniferous tree species could be altered by multiple applications of acidic fog, and by exposure to ambient O{sub 3}. In general, the alterations were slight to modest, which may be attributed to the low degree of stress severity, and the slow rate of tree growth. The findings indicate that exposure to acidic fog followed by O{sub 3} does not cause detectable changes in conifer seedling growth within a single-growing season. Nevertheless, it is clear that acidic fog and O{sub 3} cause temporal alterations in seedling physiology and biochemistry.

  19. Biosynthesis and Metabolic Fate of Phenylalanine in Conifers

    PubMed Central

    Pascual, María B.; El-Azaz, Jorge; de la Torre, Fernando N.; Cañas, Rafael A.; Avila, Concepción; Cánovas, Francisco M.

    2016-01-01

    The amino acid phenylalanine (Phe) is a critical metabolic node that plays an essential role in the interconnection between primary and secondary metabolism in plants. Phe is used as a protein building block but it is also as a precursor for numerous plant compounds that are crucial for plant reproduction, growth, development, and defense against different types of stresses. The metabolism of Phe plays a central role in the channeling of carbon from photosynthesis to the biosynthesis of phenylpropanoids. The study of this metabolic pathway is particularly relevant in trees, which divert large amounts of carbon into the biosynthesis of Phe-derived compounds, particularly lignin, an important constituent of wood. The trunks of trees are metabolic sinks that consume a considerable percentage of carbon and energy from photosynthesis, and carbon is finally immobilized in wood. This paper reviews recent advances in the biosynthesis and metabolic utilization of Phe in conifer trees. Two alternative routes have been identified: the ancient phenylpyruvate pathway that is present in microorganisms, and the arogenate pathway that possibly evolved later during plant evolution. Additionally, an efficient nitrogen recycling mechanism is required to maintain sustained growth during xylem formation. The relevance of phenylalanine metabolic pathways in wood formation, the biotic interactions, and ultraviolet protection is discussed. The genetic manipulation and transcriptional regulation of the pathways are also outlined. PMID:27468292

  20. Complete tylosis formation in a latest Permian conifer stem

    PubMed Central

    Feng, Zhuo; Wang, Jun; Rößler, Ronny; Kerp, Hans; Wei, Hai-Bo

    2013-01-01

    Background and Aims Our knowledge of tylosis formation is mainly based on observations of extant plants; however, its developmental and functional significance are less well understood in fossil plants. This study, for the first time, describes a complete tylosis formation in a fossil woody conifer and discusses its ecophysiological implications. Methods The permineralized stem of Shenoxylon mirabile was collected from the upper Permian (Changhsingian) Sunjiagou Formation of Shitanjing coalfield, northern China. Samples from different portions of the stem were prepared by using the standard thin-sectioning technique and studied in transmitted light. Key Results The outgrowth of ray parenchyma cells protruded into adjacent tracheids through pits initially forming small pyriform or balloon-shaped structures, which became globular or slightly elongated when they reached their maximum size. The tracheid luminae were gradually occluded by densely spaced tyloses. The host tracheids are arranged in distinct concentric zones representing different growth phases of tylosis formation within a single growth ring. Conclusions The extensive development of tyloses from the innermost heartwood (metaxylem) tracheids to the outermost sapwood tracheids suggests that the plant was highly vulnerable and reacted strongly to environmental stress. Based on the evidence available, the tyloses were probably not produced in response to wound reaction or pathogenic infection, since evidence of wood traumatic events or fungal invasion are not recognizable. Rather, they may represent an ecophysiological response to the constant environmental stimuli. PMID:23532049

  1. Modeling acclimation of photosynthesis to temperature in evergreen conifer forests.

    PubMed

    Gea-Izquierdo, Guillermo; Mäkelä, Annikki; Margolis, Hank; Bergeron, Yves; Black, T Andrew; Dunn, Allison; Hadley, Julian; Kyaw Tha Paw U; Falk, Matthias; Wharton, Sonia; Monson, Russell; Hollinger, David Y; Laurila, Tuomas; Aurela, Mika; McCaughey, Harry; Bourque, Charles; Vesala, Timo; Berninger, Frank

    2010-10-01

    • In this study, we used a canopy photosynthesis model which describes changes in photosynthetic capacity with slow temperature-dependent acclimations. • A flux-partitioning algorithm was applied to fit the photosynthesis model to net ecosystem exchange data for 12 evergreen coniferous forests from northern temperate and boreal regions. • The model accounted for much of the variation in photosynthetic production, with modeling efficiencies (mean > 67%) similar to those of more complex models. The parameter describing the rate of acclimation was larger at the northern sites, leading to a slower acclimation of photosynthesis to temperature. The response of the rates of photosynthesis to air temperature in spring was delayed up to several days at the coldest sites. Overall photosynthesis acclimation processes were slower at colder, northern locations than at warmer, more southern, and more maritime sites. • Consequently, slow changes in photosynthetic capacity were essential to explaining variations of photosynthesis for colder boreal forests (i.e. where acclimation of photosynthesis to temperature was slower), whereas the importance of these processes was minor in warmer conifer evergreen forests.

  2. Vigor loss in conifers due to dwarf mistletoe

    NASA Technical Reports Server (NTRS)

    Meyer, M. P.; French, D. W.; Latham, R. P.; Nelson, C. A.

    1970-01-01

    Practical remote sensing techniques were developed for detecting and evaluating vigor loss in forest conifers due to dwarf mistletoe. Eastern dwarf mistletoe (Arceuthobium pusillum) infection of black spruce (Picea mariana) was investigated. A tower-tramway system, 100 feet high, was erected over an infected stand in northeast Minnesota in June and multiband/multidate photography was initiated in July and is continuing. Four 70mm film-filter combinations were used in a multicamera unit: Plus-X/Wratten 58, Plus-X/Wratten 25A, Aero Infrared/Wratten 89B, and Ektachrome Infrared/Wratten 12. The stand of mistletoe-infected black spruce under the tramway was photographed three times per day (0900, 1200 and 1500 local sun time) at approximately 10 day intervals. An extensive test site, several square miles in area, was selected in north-central Minnesota for the purpose of testing photographic specifications developed on the tramway test site. One aerial photographic flight at a variety of altitudes was accomplished over the extensive test site in August. Data analyses are not available at this time.

  3. Detection of aspen/conifer forest mixes from multitemporal LANDSAT digital data. [Bear River Range, Rocky Mountains

    NASA Technical Reports Server (NTRS)

    Merola, J. A.; Jaynes, R. A.; Harniss, R. O.

    1983-01-01

    Aspen, conifer and mixed aspen/conifer forests were mapped for a 15-quadrangle study area in the Utah-Idaho Bear River Range using LANDSAT multispectral scanner (MSS) data. The digital MSS data were utilized to devise quantitative indices which correlate with apparently stable and seral aspen forests. The extent to which a two-date LANDSAT MSS analysis may permit the delineation of different categories of aspen/conifer forest mix was explored. Multitemporal analyses of MSS data led to the identification of early, early to mid, mid to late, and late seral stages of aspen/conifer forest mixing.

  4. Structure-function constraints of tracheid-based xylem: a comparison of conifers and ferns.

    PubMed

    Pittermann, Jarmila; Limm, Emily; Rico, Christopher; Christman, Mairgareth A

    2011-10-01

    The ferns comprise one of the most ancient tracheophytic plant lineages, and occupy habitats ranging from tundra to deserts and the equatorial tropics. Like their nearest relatives the conifers, modern ferns possess tracheid-based xylem but the structure-function relationships of fern xylem are poorly understood. Here, we sampled the fronds (megaphylls) of 16 species across the fern phylogeny, and examined the relationships among hydraulic transport, drought-induced cavitation resistance, the xylem anatomy of the stipe, and the gas-exchange response of the pinnae. For comparison, the results are presented alongside a similar suite of conifer data. Fern xylem is as resistant to cavitation as conifer xylem, but exhibits none of the hydraulic or structural trade-offs associated with resistance to cavitation. On a conduit diameter basis, fern xylem can exhibit greater hydraulic efficiency than conifer and angiosperm xylem. In ferns, wide and long tracheids compensate in part for the lack of secondary xylem and allow ferns to exhibit transport rates on a par with those of conifers. We suspect that it is the arrangement of the primary xylem, in addition to the intrinsic traits of the conduits themselves, that may help explain the broad range of cavitation resistance in ferns.

  5. Conifer genomics and adaptation: at the crossroads of genetic diversity and genome function.

    PubMed

    Prunier, Julien; Verta, Jukka-Pekka; MacKay, John J

    2016-01-01

    Conifers have been understudied at the genomic level despite their worldwide ecological and economic importance but the situation is rapidly changing with the development of next generation sequencing (NGS) technologies. With NGS, genomics research has simultaneously gained in speed, magnitude and scope. In just a few years, genomes of 20-24 gigabases have been sequenced for several conifers, with several others expected in the near future. Biological insights have resulted from recent sequencing initiatives as well as genetic mapping, gene expression profiling and gene discovery research over nearly two decades. We review the knowledge arising from conifer genomics research emphasizing genome evolution and the genomic basis of adaptation, and outline emerging questions and knowledge gaps. We discuss future directions in three areas with potential inputs from NGS technologies: the evolutionary impacts of adaptation in conifers based on the adaptation-by-speciation model; the contributions of genetic variability of gene expression in adaptation; and the development of a broader understanding of genetic diversity and its impacts on genome function. These research directions promise to sustain research aimed at addressing the emerging challenges of adaptation that face conifer trees.

  6. Mediterranean climate effects. I. Conifer water use across a Sierra Nevada ecotone.

    PubMed

    Royce, E B; Barbour, M G

    2001-05-01

    Xylem water potential of the midelevation conifers Pinus jeffreyi, Pinus lambertiana, Abies concolor, and Calocedrus decurrens, the higher elevation Pinus monticola and Abies magnifica, and co-occurring evergreen angiosperm shrubs, together with soil moisture under these plants, were monitored at three sites on the Kern Plateau in the southernmost Sierra Nevada Range of California. Site locations spanned the ecotone between the mid- and upper montane forests at elevations of 2230-2820 m. Measurements were made through a low-snowfall year and a heavy-snowfall year.In the Mediterranean climate of the Sierra Nevada, the heavy winter snowpack persists into late spring, after precipitation has effectively stopped. We found the subsequent depletion of soil moisture due to plant water uptake to result in predawn xylem water potentials for conifers more negative by 0.6-1.4 MPa than those for shrubs or inferred soil potentials. Shrubs generally depleted soil moisture more rapidly and ultimately extracted a greater fraction of the available soil moisture than did the conifers. This depletion of soil moisture by shrubs, particularly Arctostaphylos patula, may limit conifer growth and regeneration by prematurely terminating growth on the shallow soils studied. The conifers all generally showed similar patterns of soil moisture use, except that A. magnifica extracted moisture more rapidly early in the season.

  7. Estimating terpene and terpenoid emissions from conifer oleoresin composition

    NASA Astrophysics Data System (ADS)

    Flores, Rosa M.; Doskey, Paul V.

    2015-07-01

    The following algorithm, which is based on the thermodynamics of nonelectrolyte partitioning, was developed to predict emission rates of terpenes and terpenoids from specific storage sites in conifers: Ei =xoriγoripi∘ where Ei is the emission rate (μg C gdw-1 h-1) and pi∘ is the vapor pressure (mm Hg) of the pure liquid terpene or terpenoid, respectively, and xori and γori are the mole fraction and activity coefficient (on a Raoult's law convention), respectively, of the terpene and terpenoid in the oleoresin. Activity coefficients are calculated with Hansen solubility parameters that account for dispersive, polar, and H-bonding interactions of the solutes with the oleoresin matrix. Estimates of pi∘ at 25 °C and molar enthalpies of vaporization are made with the SIMPOL.1 method and are used to estimate pi∘ at environmentally relevant temperatures. Estimated mixing ratios of terpenes and terpenols were comparatively higher above resin-acid- and monoterpene-rich oleoresins, respectively. The results indicated a greater affinity of terpenes and terpenols for the non-functionalized and carboxylic acid containing matrix through dispersive and H-bonding interactions, which are expressed in the emission algorithm by the activity coefficient. The correlation between measured emission rates of terpenes and terpenoids for Pinus strobus and emission rates predicted with the algorithm were very good (R = 0.95). Standard errors for the range and average of monoterpene emission rates were ±6 - ±86% and ±54%, respectively, and were similar in magnitude to reported standard deviations of monoterpene composition of foliar oils (±38 - ±51% and ±67%, respectively).

  8. Simulation of growth of Adirondack conifers in relation to global climate change

    SciTech Connect

    Pan, Y.; Raynal, D.J. )

    1993-06-01

    Several conifer species grown in plantations in the southeastern Adirondack mountains of New York were chosen to model tree growth. In the models, annual xylem growth was decomposed into several components that reflect various intrinsic or extrinsic factors. Growth signals indicative of climatic effects were used to construct response functions using both multivariate analysis and Kalman filter methods. Two models were used to simulate tree growth response to future CO[sub 2]-induced climate change projected by GCMs. The comparable results of both models indicate that different conifer species have individualistic growth responses to future climatic change. The response behaviors of trees are affected greatly by local stand conditions. The results suggest possible changes in future growth and distributions of naturally occurring conifers in this region.

  9. Infrared radiation from hot cones on cool conifers attracts seed-feeding insects

    PubMed Central

    Takács, Stephen; Bottomley, Hannah; Andreller, Iisak; Zaradnik, Tracy; Schwarz, Joseph; Bennett, Robb; Strong, Ward; Gries, Gerhard

    2008-01-01

    Foraging animals use diverse cues to locate resources. Common foraging cues have visual, auditory, olfactory, tactile or gustatory characteristics. Here, we show a foraging herbivore using infrared (IR) radiation from living plants as a host-finding cue. We present data revealing that (i) conifer cones are warmer and emit more near-, mid- and long-range IR radiation than needles, (ii) cone-feeding western conifer seed bugs, Leptoglossus occidentalis (Hemiptera: Coreidae), possess IR receptive organs and orient towards experimental IR cues, and (iii) occlusion of the insects' IR receptors impairs IR perception. The conifers' cost of attracting cone-feeding insects may be offset by occasional mast seeding resulting in cone crops too large to be effectively exploited by herbivores. PMID:18945664

  10. Infrared radiation from hot cones on cool conifers attracts seed-feeding insects.

    PubMed

    Takács, Stephen; Bottomley, Hannah; Andreller, Iisak; Zaradnik, Tracy; Schwarz, Joseph; Bennett, Robb; Strong, Ward; Gries, Gerhard

    2009-02-22

    Foraging animals use diverse cues to locate resources. Common foraging cues have visual, auditory, olfactory, tactile or gustatory characteristics. Here, we show a foraging herbivore using infrared (IR) radiation from living plants as a host-finding cue. We present data revealing that (i) conifer cones are warmer and emit more near-, mid- and long-range IR radiation than needles, (ii) cone-feeding western conifer seed bugs, Leptoglossus occidentalis (Hemiptera: Coreidae), possess IR receptive organs and orient towards experimental IR cues, and (iii) occlusion of the insects' IR receptors impairs IR perception. The conifers' cost of attracting cone-feeding insects may be offset by occasional mast seeding resulting in cone crops too large to be effectively exploited by herbivores.

  11. A comparison of spectral reflectance properties at the needle, branch, and canopy level for selected conifer species

    NASA Technical Reports Server (NTRS)

    Williams, Darrel L.

    1991-01-01

    Radiative transfer data were collected for three conifer species and a northern hardwood species. The data indicate that conifer forests are more absorptive than broadleaved, deciduous hardwood forests. In particular, spruce species have an enhanced capability of absorbing incoming solar radiation in the optical wavelength region.

  12. The problem of conifer species migration lag in the Pacific Northwest region since the last glaciation

    NASA Astrophysics Data System (ADS)

    Elias, Scott A.

    2013-10-01

    Multiproxy evidence indicates that warmer-than-present summers became established in Eastern Beringia as early as 14,000-13,000 years ago, but the dispersal of spruces, pines, cedars and hemlocks across the Pacific Northwest (PNW) region of southern Alaska did not begin until at least 1500 years afterwards, and took many thousands of years to be completed. There are many potential reasons for this slow spread of PNW conifers towards their modern range limits. The absence of mycorrhizae in the soils of southern Alaska may have slowed conifer establishment. The availability of soil moisture was another limiting factor. With the exception of Pinus contorta, the other PNW conifers become established most readily from seeds that fall on moist, shaded substrates, thus they are not good pioneering species. Competition with alder and birch played an important role, especially along Prince William Sound and the Kenai Peninsula. Alder or alder and birch dominated these regions until the mid- to late Holocene. The other key element for most PNW conifer species is the precipitation regime. The hemlocks, cedars and Sitka spruce are not drought-hardy. So although the PNW temperature regime may have been warm enough in early postglacial times to support the growth of PNW conifers, it was probably too dry for them to successfully become established in new regions. The conflation of these environmental factors limits our present understanding of the problem, but the recent trend of multi-proxy analysis in Quaternary paleoecology will certainly sharpen our reconstructions. Such proxies as conifer needle stomata and insect fossil remains hold significant promise.

  13. Three centuries of managing introduced conifers in South Africa: Benefits, impacts, changing perceptions and conflict resolution.

    PubMed

    van Wilgen, Brian W; Richardson, David M

    2012-09-15

    Alien conifers, mainly pines, have been planted in South Africa for a range of purposes for over 300 years. Formal plantations cover 660,000 ha of the country, and invasive stands of varying density occur on a further 2.9 million ha. These trees have brought many benefits but have also caused unintended problems. The management of alien conifers has evolved in response to emerging problems such as excessive water use by plantations of conifers, changing values and markets, and the realities of a new ecological order brought about by invasive alien conifers. This paper reviews the history of conifer introductions to South Africa, the benefits and impacts with which they are associated, and the ongoing and evolving research that has been conducted to inform their management. The South African approach has included taking courageous steps to address the problem of highly invasive species that are also an important commercial crop. These interventions have not, however, had the desired effect of both retaining benefits from formal plantations while simultaneously reversing the trend of growing impacts associated with self-sown invasive stands. We suggest that different approaches need to be considered, including the systematic phasing out of commercial forestry in zones where it delivers low returns, and the introduction of more effective, focussed and integrated, region-specific approaches to the management of invasive stands of conifers. These steps would deliver much improved economic outcomes by protecting valuable ecosystem services, but will require political commitment to policies that could be unpopular in certain sectors of society.

  14. Detection of aspen-conifer forest mixes from LANDSAT digital data. [Utah-Idaho Bear River Range

    NASA Technical Reports Server (NTRS)

    Jaynes, R. A.; Merola, J. A.

    1982-01-01

    Aspen, conifer and mixed aspen/conifer forests were mapped for a 15-quadrangle study area in the Utah-Idaho Bear River Range using LANDSAT multispectral scanner data. Digital classification and statistical analysis of LANDSAT data allowed the identification of six groups of signatures which reflect different types of aspen/conifer forest mixing. Photo interpretations of the print symbols suggest that such classes are indicative of mid to late seral aspen forests. Digital print map overlays and acreage calculations were prepared for the study area quadrangles. Further field verification is needed to acquire additional information about the nature of the forests. Single date LANDSAT analysis should be a cost effective means to index aspen forests which are at least in the mid seral phase of conifer invasion. Since aspen canopies tend to obscure understory conifers for early seral forests, a second date analysis, using data taken when aspens are leafless, could provide information about early seral aspen forests.

  15. Detection of aspen/conifer forest mixes from multitemporal Landsat digital data. [Utah-Idaho Bear River Range

    NASA Technical Reports Server (NTRS)

    Merola, J. A.; Jaynes, R. A.; Harniss, R. O.

    1984-01-01

    Aspen, conifer and mixed aspen/conifer forests were mapped for a 15-quadrangle study area in the Utah-Idaho Bear River Range using Landsat multispectral scanner data. Digital classification and statistical analysis of Landsat data allowed the identification of six groups of signatures which reflect different types of aspen/conifer forest mixing. Photo interpretations of the print symbols suggest that such classes are indicative of mid to late seral aspen forests. Digital print map overlayes and acreage calculations were prepared for the study area quadrangles. Further field verification is needed to acquire additional information about the nature of the forests. Single data Landsat analysis should be a cost effective means to index aspen forests which are at least in the mid seral phase of conifer invasion. Since aspen canopies tend to obscure understory conifers for early seral forests, a second data analysis, using data taken when aspens are leafless, could provide information about early seral aspen forests.

  16. Assessing Conifer Ray Parenchyma for Ecological Studies: Pitfalls and Guidelines

    PubMed Central

    von Arx, Georg; Arzac, Alberto; Olano, José M.; Fonti, Patrick

    2015-01-01

    provided the least accurate PERPAR estimates. This evaluation of ray parenchyma in conifers and the presented guidelines regarding data accuracy as a function of measured wood surface and number of samples represent an important methodological reference for ray quantification, which will ultimately improve the understanding of the fundamental role of ray parenchyma tissue for the performance and survival of trees growing in stressed environments. PMID:26635842

  17. Diagenesis of conifer needles in a coastal marine environment

    NASA Astrophysics Data System (ADS)

    Hedges, John I.; Weliky, K.

    1989-10-01

    (C/V) of the deepest sedimentary fir/hemlock needles to 20% of the original value and almost tripled the carbon-normalized yield of total vanillyl plus cinnamyl phenols (Λ). The net result of these compositional variations was to make the lignin component of the buried conifer needles resemble lignin in gymnosperm wood, thereby leading to underestimates of needle input and mass.

  18. Stem demography and postfire recruitment of a resprouting serotinous conifer

    USGS Publications Warehouse

    Keeley, Jon E.; Keeley, Melanie B.; Bond, William J.

    1999-01-01

    The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4–9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionallyWiddring-tonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fires, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in theCupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait

  19. Assessing Conifer Ray Parenchyma for Ecological Studies: Pitfalls and Guidelines.

    PubMed

    von Arx, Georg; Arzac, Alberto; Olano, José M; Fonti, Patrick

    2015-01-01

    provided the least accurate PERPAR estimates. This evaluation of ray parenchyma in conifers and the presented guidelines regarding data accuracy as a function of measured wood surface and number of samples represent an important methodological reference for ray quantification, which will ultimately improve the understanding of the fundamental role of ray parenchyma tissue for the performance and survival of trees growing in stressed environments. PMID:26635842

  20. The impact of catchment conifer plantation forestry on the hydrochemistry of peatland lakes.

    PubMed

    Drinan, T J; Graham, C T; O'Halloran, J; Harrison, S S C

    2013-01-15

    The hydrochemistry of 26 small blanket bog lakes was examined to assess the impact of conifer plantation forestry on lake water chemistry. Lakes were selected from three distinct catchment land use categories: i) unplanted blanket bog only present in the catchment, ii) mature (closed-canopy) conifer plantation forests only present in the catchment and iii) catchments containing mature conifer plantation forests with recently clearfelled areas. All three catchment land uses were replicated across two geologies: sedimentary (sandstone) and igneous (granite). Lakes with afforested catchments across both geologies had elevated concentrations of phosphorus (P), nitrogen (N), total dissolved organic carbon (TDOC), aluminium (Al) and iron (Fe), with the highest concentrations of each parameter recorded from lakes with catchment clearfelling. Dissolved oxygen was also significantly reduced in the afforested lakes, particularly the clearfell lakes. Analysis of runoff from a nearby recently clearfelled site revealed high biological and chemical oxygen demands, consistent with at least part of the elevated concentrations of TDOC emanating from clearfelled sites having higher biochemical lability. Inorganic fertilisers applied at the start of the forest cycle, the decay of the underlying peat soil and accumulated surface tree litter, and leachate from felled trees are the likely sources of the elevated concentrations of plant nutrients, TDOC, heavy metals and major ions, with excessive peat soil disturbance during clearfelling likely exacerbating the runoff into lakes. Our study has demonstrated a clear, deleterious impact of conifer plantations on the water quality draining from blanket bog catchments, with major implications for the management of afforested peatlands.

  1. Response of conifer-encroached shrublands in the Great Basin to prescribed fire and mechanical treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In response to the recent expansion of piñon and juniper woodlands into sagebrush steppe communities in the northern Great Basin region, numerous conifer removal projects have been implemented at sites having a wide range of environmental conditions. Response has varied from successful restoration t...

  2. Repeated freeze-thaw cycles induce embolism in drought stressed conifers (Norway spruce, stone pine).

    PubMed

    Mayr, Stefan; Gruber, Andreas; Bauer, Helmut

    2003-07-01

    Freezing and thawing lead to xylem embolism when gas bubbles caused by ice formation expand during the thaw process. However, previous experimental studies indicated that conifers are resistant to freezing-induced embolism, unless xylem pressure becomes very negative during the freezing. In this study, we show that conifers experienced freezing-induced embolism when exposed to repeated freeze-thaw cycles and simultaneously to drought. Simulating conditions at the alpine timberline (128 days with freeze-thaw events and thawing rates of up to 9.5 K h(-1) in the xylem of exposed twigs during winter), young trees of Norway spruce [Picea abies (L.) Karst.] and stone pine (Pinus cembra L.) were exposed to 50 and 100 freeze-thaw cycles. This treatment caused a significant increase in embolism rates in drought-stressed samples. Upon 100 freeze-thaw cycles, vulnerability thresholds (50% loss of conductivity) were shifted 1.8 MPa (Norway spruce) and 0.8 MPa (stone pine) towards less negative water potentials. The results demonstrate that freeze-thaw cycles are a possible reason for winter-embolism in conifers observed in several field studies. Freezing-induced embolism may contribute to the altitudinal limits of conifers.

  3. The sage-grouse habitat mortgage: effective conifer management in space and time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of conservation-reliant species can be complicated by the need to manage ecosystem processes that operate at extended temporal horizons. One such process is the role of fire in regulating abundance of expanding conifers that disrupt sage-grouse habitat in the northern Great Basin of the ...

  4. Impact of conifer forest litter on microwave emission at L-band

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study reports on the utilization of microwave modeling, together with ground truth and L-bank (1.4 GHz) brightness temperatures to investigate the characteristics of conifer forest floor. The microwave data were acquired over natural Virginia pine forest in Maryland by ComRAD, a ground-based mi...

  5. Bird communities associated with succession and management of lowland conifer forests

    USGS Publications Warehouse

    Dawson, D.K.

    1979-01-01

    Data from published bird censuses were used to determine changes in avian communities in relation to plant succession, fire, type conversion, and timber management practices in lowland conifer forests in the northeastern United States. With modifications in current logging practices, habitat for the bird species that nest in undisturbed stands can be provided. Management guidelines are recommended.

  6. In vivo 13C NMR metabolite profiling: potential for understanding and assessing conifer seed quality.

    PubMed

    Terskikh, Victor V; Feurtado, J Allan; Borchardt, Shane; Giblin, Michael; Abrams, Suzanne R; Kermode, Allison R

    2005-08-01

    High-resolution 13C MAS NMR spectroscopy was used to profile a range of primary and secondary metabolites in vivo in intact whole seeds of eight different conifer species native to North America, including six of the Pinaceae family and two of the Cupressaceae family. In vivo 13C NMR provided information on the total seed oil content and fatty acid composition of the major storage lipids in a non-destructive manner. In addition, a number of monoterpenes were identified in the 13C NMR spectra of conifer seeds containing oleoresin; these compounds showed marked variability in individual seeds of Pacific silver fir within the same seed lot. In imbibed conifer seeds, the 13C NMR spectra showed the presence of considerable amounts of dissolved sucrose presumed to play a protective role in the desiccation-tolerance of seeds. The free amino acids arginine and asparagine, generated as a result of storage protein mobilization, were detected in vivo during seed germination and early seedling growth. The potential for NMR to profile metabolites in a non-destructive manner in single conifer seeds and seed populations is discussed. It is a powerful tool to evaluate seed quality because of its ability to assess reserve accumulation during seed development or at seed maturity; it can also be used to monitor reserve mobilization, which is critical for seedling emergence. PMID:15996983

  7. Antifungal activity of extracts and select compounds in heartwood of seven western conifers toward Phytophthora ramorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Individual compounds and ethyl acetate extracts from heartwood of seven conifer species were tested for fungicidal activity against Phytophthora ramorum. Extracts from incense and western red cedar exhibited the strongest activity (EC50 589 and 646 ppm, respectively), yellow-cedar, western juniper,...

  8. Leaf wax composition and carbon isotopes vary among major conifer groups

    NASA Astrophysics Data System (ADS)

    Diefendorf, Aaron F.; Leslie, Andrew B.; Wing, Scott L.

    2015-12-01

    Leaf waxes (e.g. n-alkanes, n-alkanoic acids) and their carbon isotopes (δ13C) are commonly used to track past changes in the carbon cycle, water availability, and plant ecophysiology. Previous studies indicated that conifers have lower n-alkane concentrations than angiosperms and that 13C fractionation during n-alkane synthesis (εn-alkane) is smaller than in angiosperms. These prior studies, however, sampled a limited phylogenetic and geographic subset of conifers, leaving out many important subtropical and Southern Hemisphere groups that were once widespread and common components of fossil assemblages. To expand on previous work, we collected 43 conifer species (and Ginkgo biloba) from the University of California Botanical Garden at Berkeley, sampling all extant conifer families and almost two-thirds of extant genera. We find that Pinaceae, including many North American species used in previous studies, have very low or no n-alkanes. However, other conifer groups have significant concentrations of n-alkanes, especially Southern Hemisphere Araucariaceae and Podocarpaceae (monkey puzzles, Norfolk Island pines, and yellowwoods), and many species of Cupressaceae (junipers and relatives). Within the Cupressaceae, we find total n-alkane concentrations are high in subfamilies Cupressoideae and Callitroideae, but significantly lower in the early diverging taxodioid lineages (including bald cypress and redwood). Individual n-alkane chain lengths have a weak phylogenetic signal, except for n-C29 alkane, but when combined using average chain length (ACL), a strong phylogenetic signal emerges. The strong phylogenetic signal in ACL, observed in the context of a common growth environment for all plants we sampled, suggests that ACL is strongly influenced by factors other than climate. An analysis of εn-alkane indicates a strong phylogenetic signal in which the smallest biosynthetic fractionation occurs in Pinaceae and the largest in Taxaceae (yews and relatives). The

  9. IDENTIFICATION AND EMISSION FACTORS OF MOLECULAR TRACERS IN ORGANIC AEROSOLS FROM BIOMASS BURNING PART 1. TEMPERATE CLIMATE CONIFERS. (R823990)

    EPA Science Inventory

    Smoke particulate matter from conifers subjected to controlled burning, both under smoldering and flaming conditions, was sampled by high volume air filtration on precleaned quartz fiber filters. The filtered particles were extracted with dichloromethane and the crude extracts...

  10. Determination of variability in leaf biomass densities of conifers and mixed conifers under different environmental conditions in the San Joaquin Valley air basin. Final report

    SciTech Connect

    Temple, P.J.; Mutters, R.J.; Adams, C.; Greene, J.; Jackson, R.

    1995-06-01

    Biomass sampling plots were established at 29 locations within the dominant vegetation zones of the study area. Estimates of foliar biomass were made for each plot by three independent methods: regression analysis on the basis of tree diameter, calculation of the amount of light intercepted by the leaf canopy, and extrapolation from branch leaf area. Multivariate regression analysis was used to relate these foliar biomass estimates for oak plots and conifer plots to several independent predictor variables, including elevation, slope, aspect, temperature, precipitation, and soil chemical characteristics.

  11. Hydraulic safety margins and embolism reversal in stems and leaves: why are conifers and angiosperms so different?

    PubMed

    Johnson, Daniel M; McCulloh, Katherine A; Woodruff, David R; Meinzer, Frederick C

    2012-10-01

    Angiosperm and coniferous tree species utilize a continuum of hydraulic strategies. Hydraulic safety margins (defined as differences between naturally occurring xylem pressures and pressures that would cause hydraulic dysfunction, or differences between pressures resulting in loss of hydraulic function in adjacent organs (e.g., stems vs. leaves) tend to be much greater in conifers than angiosperms and serve to prevent stem embolism. However, conifers tend to experience embolism more frequently in leaves and roots than angiosperms. Embolism repair is thought to occur by active transport of sugars into empty conduits followed by passive water movement. The most likely source of sugar for refilling is from nonstructural carbohydrate depolymerization in nearby parenchyma cells. Compared to angiosperms, conifers tend to have little parenchyma or nonstructural carbohydrates in their wood. The ability to rapidly repair embolisms may rely on having nearby parenchyma cells, which could explain the need for greater safety margins in conifer wood as compared to angiosperms. The frequent embolisms that occur in the distal portions of conifers are readily repaired, perhaps due to the abundant parenchyma in leaves and roots, and these distal tissues may act as hydraulic circuit breakers that prevent tension-induced embolisms in the attached stems. Frequent embolisms in conifer leaves may also be due to weaker stomatal response to changes in ambient humidity. Although there is a continuum of hydraulic strategies among woody plants, there appear to be two distinct 'behaviors' at the extremes: (1) embolism prevention and (2) embolism occurrence and subsequent repair.

  12. Hydraulic safety margins and embolism reversal in stems and leaves: why are conifers and angiosperms so different?

    PubMed

    Johnson, Daniel M; McCulloh, Katherine A; Woodruff, David R; Meinzer, Frederick C

    2012-10-01

    Angiosperm and coniferous tree species utilize a continuum of hydraulic strategies. Hydraulic safety margins (defined as differences between naturally occurring xylem pressures and pressures that would cause hydraulic dysfunction, or differences between pressures resulting in loss of hydraulic function in adjacent organs (e.g., stems vs. leaves) tend to be much greater in conifers than angiosperms and serve to prevent stem embolism. However, conifers tend to experience embolism more frequently in leaves and roots than angiosperms. Embolism repair is thought to occur by active transport of sugars into empty conduits followed by passive water movement. The most likely source of sugar for refilling is from nonstructural carbohydrate depolymerization in nearby parenchyma cells. Compared to angiosperms, conifers tend to have little parenchyma or nonstructural carbohydrates in their wood. The ability to rapidly repair embolisms may rely on having nearby parenchyma cells, which could explain the need for greater safety margins in conifer wood as compared to angiosperms. The frequent embolisms that occur in the distal portions of conifers are readily repaired, perhaps due to the abundant parenchyma in leaves and roots, and these distal tissues may act as hydraulic circuit breakers that prevent tension-induced embolisms in the attached stems. Frequent embolisms in conifer leaves may also be due to weaker stomatal response to changes in ambient humidity. Although there is a continuum of hydraulic strategies among woody plants, there appear to be two distinct 'behaviors' at the extremes: (1) embolism prevention and (2) embolism occurrence and subsequent repair. PMID:22920998

  13. A comparative field study of growth and survival of Sierran conifer seedlings

    SciTech Connect

    Kern, R.A.

    1996-12-31

    This study is a comparison of seedling growth and survival of seven species of conifers that make up the mid-elevation Sierra Nevada mixed conifer forest--Abies concolor, Abies magnifica, Calocedrus decurrens, Pinus jeffreyi, Pinus lambertiana, Pinus ponderosa, and Sequoiadendron giganteum. The field experiment was designed to test the hypothesis that seedling demography is affected by the study species` relatively shade and drought tolerances. Six discrete treatments were created in the first experiment by using three elevations (1,600 m, 1,900, m, and 2,200 m) and two natural light levels (closed canopy shade and open gap sun) at each elevation. One or two-year old seedlings were planted in the ground in replicate plots in each treatment and followed for two growing seasons. Four responses were analyzed--survival, height growth, diameter growth, and mass growth (total mass as well as root mass and shoot mass separately).

  14. Nutrient leaching from conifer needles in relation to foliar apoplast cation-exchange capacity

    SciTech Connect

    Turner, D.P.; van Broekhuizen, H.J.

    1992-01-01

    Limited evidence to date suggests that acidic precipitation promotes leaching of nutrient cations from conifer foliage. In order to evaluate the relative contribution of the apoplast cation exchange complex and symplast nutrient pools to the leached ions, the magnitude of potential foliar leaching in response to acidic precipitation was compared to foliar apoplast cation exchange capacity (CEC) for two conifer tree species (Pseudotsuga menziesii and Picea engelmanii). Leaching increased with decreasing pH and increasing time of immersion. At pH 2.1 and 3.1, equivalents of H+ depleted from the acidic solutions approximated equivalent of cations gained by the solutions. Maximum amounts leached were less than 40 micro equiv/g dry weight of needles for all ions combined. Measured foliar apoplast CEC for these species was approximately 120 micro equiv/g dry weight of needles. These relative magnitudes indicated that the apoplast provided the leached ions.

  15. Seed plant phylogeny: gnetophytes are derived conifers and a sister group to Pinaceae.

    PubMed

    Hajibabaei, Mehrdad; Xia, Junnan; Drouin, Guy

    2006-07-01

    The phylogenetic position of gnetophytes has long been controversial. We sequenced parts of the genes coding for the largest subunit of nuclear RNA polymerase I, II, and III and combined these sequences with those of four chloroplast genes, two mitochondrial genes, and 18S rRNA genes to address this issue. Both maximum likelihood and maximum parsimony analyses of the sites not affected by high substitution levels strongly support a phylogeny where gymnosperms and angiosperms are monophyletic, where cycads are at the base of gymnosperm tree and are followed by ginkgos, and where gnetophytes are grouped within conifers as the sister group of pines. The evolution of several morphological and molecular characters of gnetophytes and conifers will therefore need to be reinterpreted. PMID:16621615

  16. Fine root dynamics and forest production across a calcium gradient in northern hardwood and conifer ecosystems

    USGS Publications Warehouse

    Park, B.B.; Yanai, R.D.; Fahey, T.J.; Bailey, S.W.; Siccama, T.G.; Shanley, J.B.; Cleavitt, N.L.

    2008-01-01

    Losses of soil base cations due to acid rain have been implicated in declines of red spruce and sugar maple in the northeastern USA. We studied fine root and aboveground biomass and production in five northern hardwood and three conifer stands differing in soil Ca status at Sleepers River, VT; Hubbard Brook, NH; and Cone Pond, NH. Neither aboveground biomass and production nor belowground biomass were related to soil Ca or Ca:Al ratios across this gradient. Hardwood stands had 37% higher aboveground biomass (P = 0.03) and 44% higher leaf litter production (P < 0.01) than the conifer stands, on average. Fine root biomass (<2 mm in diameter) in the upper 35 cm of the soil, including the forest floor, was very similar in hardwoods and conifers (5.92 and 5.93 Mg ha-1). The turnover coefficient (TC) of fine roots smaller than 1 mm ranged from 0.62 to 1.86 y-1 and increased significantly with soil exchangeable Ca (P = 0.03). As a result, calculated fine root production was clearly higher in sites with higher soil Ca (P = 0.02). Fine root production (biomass times turnover) ranged from 1.2 to 3.7 Mg ha-1 y-1 for hardwood stands and from 0.9 to 2.3 Mg ha-1 y -1 for conifer stands. The relationship we observed between soil Ca availability and root production suggests that cation depletion might lead to reduced carbon allocation to roots in these ecosystems. ?? 2008 Springer Science+Business Media, LLC.

  17. A Water Budget Approach to Study the Hydrologic Response of Mountain Meadow Restoration Following Conifer Removal

    NASA Astrophysics Data System (ADS)

    Van Oosbree, G. F.; Surfleet, C. G.; Jasbinsek, J. J.

    2014-12-01

    Mountain meadows are important ecological habitats that have degraded in quality and distribution due to fire suppression and poor land use practices in the Sierra Nevada Mountains. Conifer encroachment in mountain meadows has accelerated and is one of the reasons for the decline of meadow habitat. To date there are few studies which quantify the hydrologic response of meadow restoration due to vegetation or conifer removal. This study is using a before after control intervention (BACI) study design to determine the hydrologic response of restoration to a historic meadow encroached by conifers (study meadow). A water budget approach has been developed to quantify the hydrology of the control and study meadow before and after restoration. Measurements of groundwater depth and soil moisture are currently being taken on the control and study meadows. A total of 14 Odyssey water level capacitance instruments were installed to a 1.5 meter depth and 14 soil moisture instruments were installed to a 30 cm depth using a spatially balanced random sampling approach. Electrical resistivity imaging (ERI) was used to determine soil moisture and depth to groundwater across forest-meadow ecotones present on the meadows. Additionally, ERI was used to extrapolate point measurements of groundwater depth and soil moisture across the study and control areas. The weekly water budget indicates differences between the control meadow and study meadow in the first year prior to conifer removal. The ERI indicated differences in sub surface geology, soil moisture, and groundwater depth both between the control and study meadows and along the forest-meadow ecotones. ERI was demonstrated to improve the spatial extrapolation of soil moisture and groundwater point measurements.

  18. Agroforestry: Conifers. (Latest citations from the Cab Abstracts database). NewSearch

    SciTech Connect

    Not Available

    1994-10-01

    The bibliography contains citations concerning the use of lands forested with conifers for crop and livestock production. Citations cover the grazing of livestock and the production of crops, including tomatoes, soybeans, lespedeza, wheat, rape, taro, cotton, cabbages, ginger, watermelons, and strawberries. Livestock discussed include cattle, sheep, geese, and horses. Economic analyses and economic models are presented. (Contains a minimum of 147 citations and includes a subject term index and title list.)

  19. Cone selection by Eurasian red squirrels in mixed conifer forests in the Italian Alps

    NASA Astrophysics Data System (ADS)

    Molinari, A.; Wauters, L. A.; Airoldi, G.; Cerinotti, F.; Martinoli, A.; Tosi, G.

    2006-07-01

    Tree squirrels are arboreal granivores that harvest and consume tree seeds both prior to and after seed-dispersal. Inter- and intraspecific patterns of seed predation suggest that squirrels may exert strong selective pressure on cone morphology and patterns of cone production, and suggest coevolutionary interactions between squirrels and conifers. In some pine species (genus Pinus), mutualistic relationships have evolved between cone (seed) traits and seed-dispersal behaviour by birds and rodents. In other species, feeding by seed predators has selected for cone traits that decrease intensity of seed consumption. In mixed conifer forests, red squirrels ( Sciurus vulgaris) feed intensively in some (target) trees but avoid others (nontarget trees). Here we explore defensive cone traits and seed traits correlated with tree selection for conifer species with different seed-dispersal strategies. No selection for cone traits existed in Pinus cembra, which has large wingless seeds, dispersed by birds and rodents. In Picea abies, the most favoured species, target trees had cones with more seeds per cone than nontarget trees, and number of seeds increased with cone length. Cone selection was most pronounced in Pinus sylvestris, where target trees had bigger cones with more seeds and higher total seed mass than nontarget trees. However, ratio of seed mass on cone mass did not differ among target and nontarget trees, suggesting that bigger cones also had more protective tissue, probably increasing difficulties for seed predators to gain access to seeds. Our results suggest that cone and seed traits of P. cembra facilitate seed consumption by squirrels, but that defensive cone traits of small-seeded conifers, in combination with annual differences in seed production (masting), might be the result of coevolution with seed-eating squirrels.

  20. Biomolecules preserved in ca. 168 million year old fossil conifer wood

    NASA Astrophysics Data System (ADS)

    Marynowski, Leszek; Otto, Angelika; Zatoń, Michał; Philippe, Marc; Simoneit, Bernd R. T.

    2007-03-01

    Biomarkers are widely known to occur in the fossil record, but the unaltered biomolecules are rarely reported from sediments older than Paleogene. Polar terpenoids, the natural products most resistant to degradation processes, were reported mainly from the Tertiary conifers, and the oldest known are Cretaceous in age. In this paper, we report the occurrence of relatively high concentrations of ferruginol derivatives and other polar diterpenoids, as well as their diagenetic products, in a conifer wood Protopodocarpoxylon from the Middle Jurassic of Poland. Thus, the natural product terpenoids reported in this paper are definitely the oldest polar biomolecules detected in geological samples. The extracted phenolic abietanes like ferruginol and its derivatives (6,7-dehydroferruginol, sugiol, 11,14-dioxopisiferic acid) are produced only by distinct conifer families (Cupressaceae s. l., Podocarpaceae and Araucariaceae), to which Protopodocarpoxylon could belong based on anatomical characteristics. Therefore, the natural product terpenoids are of great advantage in systematics of fossil plant remains older than Paleogene and lacking suitable anatomical preservation.

  1. Electrodeposited Nanolaminated CoNiFe Cores for Ultracompact DC-DC Power Conversion

    SciTech Connect

    Kim, J; Kim, M; Herrault, F; Park, JY; Allen, MG

    2015-09-01

    Laminated metallic alloy cores (i.e., alternating layers of thin film metallic alloy and insulating material) of appropriate lamination thickness enable suppression of eddy current losses at high frequencies. Magnetic cores comprised of many such laminations yield substantial overall magnetic volume, thereby enabling high-power operation. Previously, we reported nanolaminated permalloy (Ni-80 Fe-20) cores based on a sequential electrodeposition technique, demonstrating negligible eddy current losses at peak flux densities up to 0.5 T and operating at megahertz frequencies. This paper demonstrates improved performance of nanolaminated cores comprising tens to hundreds of layers of 300-500-nm-thick CoNiFe films that exhibit superior magnetic properties (e.g., higher saturation flux density and lower coercivity) than permalloy. Nanolaminated CoNiFe cores can be operated up to a peak flux density of 0.9 T, demonstrating improved power handling capacity and exhibiting 30% reduced volumetric core loss, attributed to lowered hysteresis losses compared to the nanolaminated permalloy core of the same geometry. Operating these cores in a buck dc-dc power converter at a switching frequency of 1 MHz, the nanolaminated CoNiFe cores achieved a conversion efficiency exceeding 90% at output power levels up to 7 W, compared to an achieved permalloy core conversion efficiency below 86% at 6 W.

  2. An Ancient Transkingdom Horizontal Transfer of Penelope-Like Retroelements from Arthropods to Conifers.

    PubMed

    Lin, Xuan; Faridi, Nurul; Casola, Claudio

    2016-01-01

    Comparative genomics analyses empowered by the wealth of sequenced genomes have revealed numerous instances of horizontal DNA transfers between distantly related species. In eukaryotes, repetitive DNA sequences known as transposable elements (TEs) are especially prone to move across species boundaries. Such horizontal transposon transfers, or HTTs, are relatively common within major eukaryotic kingdoms, including animals, plants, and fungi, while rarely occurring across these kingdoms. Here, we describe the first case of HTT from animals to plants, involving TEs known as Penelope-like elements, or PLEs, a group of retrotransposons closely related to eukaryotic telomerases. Using a combination of in situ hybridization on chromosomes, polymerase chain reaction experiments, and computational analyses we show that the predominant PLE lineage, EN(+)PLEs, is highly diversified in loblolly pine and other conifers, but appears to be absent in other gymnosperms. Phylogenetic analyses of both protein and DNA sequences reveal that conifers EN(+)PLEs, or Dryads, form a monophyletic group clustering within a clade of primarily arthropod elements. Additionally, no EN(+)PLEs were detected in 1,928 genome assemblies from 1,029 nonmetazoan and nonconifer genomes from 14 major eukaryotic lineages. These findings indicate that Dryads emerged following an ancient horizontal transfer of EN(+)PLEs from arthropods to a common ancestor of conifers approximately 340 Ma. This represents one of the oldest known interspecific transmissions of TEs, and the most conspicuous case of DNA transfer between animals and plants. PMID:27190138

  3. An Ancient Transkingdom Horizontal Transfer of Penelope-Like Retroelements from Arthropods to Conifers

    PubMed Central

    Lin, Xuan; Faridi, Nurul; Casola, Claudio

    2016-01-01

    Comparative genomics analyses empowered by the wealth of sequenced genomes have revealed numerous instances of horizontal DNA transfers between distantly related species. In eukaryotes, repetitive DNA sequences known as transposable elements (TEs) are especially prone to move across species boundaries. Such horizontal transposon transfers, or HTTs, are relatively common within major eukaryotic kingdoms, including animals, plants, and fungi, while rarely occurring across these kingdoms. Here, we describe the first case of HTT from animals to plants, involving TEs known as Penelope-like elements, or PLEs, a group of retrotransposons closely related to eukaryotic telomerases. Using a combination of in situ hybridization on chromosomes, polymerase chain reaction experiments, and computational analyses we show that the predominant PLE lineage, EN(+)PLEs, is highly diversified in loblolly pine and other conifers, but appears to be absent in other gymnosperms. Phylogenetic analyses of both protein and DNA sequences reveal that conifers EN(+)PLEs, or Dryads, form a monophyletic group clustering within a clade of primarily arthropod elements. Additionally, no EN(+)PLEs were detected in 1,928 genome assemblies from 1,029 nonmetazoan and nonconifer genomes from 14 major eukaryotic lineages. These findings indicate that Dryads emerged following an ancient horizontal transfer of EN(+)PLEs from arthropods to a common ancestor of conifers approximately 340 Ma. This represents one of the oldest known interspecific transmissions of TEs, and the most conspicuous case of DNA transfer between animals and plants. PMID:27190138

  4. A comparative study of modern and fossil cone scales and seeds of conifers: A geochemical approach

    USGS Publications Warehouse

    Artur, Stankiewicz B.; Mastalerz, Maria; Kruge, M.A.; Van Bergen, P. F.; Sadowska, A.

    1997-01-01

    Modern cone scales and seeds of Pinus strobus and Sequoia sempervirens, and their fossil (Upper Miocene, c. 6 Mar) counterparts Pinus leitzii and Sequoia langsdorfi have been studied using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), electron-microprobe and scanning electron microscopy. Microscopic observations revealed only minor microbial activity and high-quality structural preservation of the fossil material. The pyrolysates of both modern genera showed the presence of ligno-cellulose characteristic of conifers. However, the abundance of (alkylated)phenols and 1,2-benzenediols in modern S. sempervirens suggests the presence of non-hydrolysable tannins or abundant polyphenolic moieties not previously reported in modern conifers. The marked differences between the pyrolysis products of both modern genera are suggested to be of chemosystematic significance. The fossil samples also contained ligno-cellulose which exhibited only partial degradation, primarily of the carbohydrate constituents. Comparison between the fossil cone scale and seed pyrolysates indicated that the ligno-cellulose complex present in the seeds is chemically more resistant than that in the cone scales. Principal component analysis (PCA) of the pyrolysis data allowed for the determination of the discriminant functions used to assess the extent of degradation and the chemosystematic differences between both genera and between cone scales and seeds. Elemental composition (C, O, S), obtained using electron-microprobe, corroborated the pyrolysis results. Overall, the combination of chemical, microscopic and statistical methods allowed for a detailed characterization and chemosystematic interpretations of modern and fossil conifer cone scales and seeds.

  5. Nuclear DNA content affects the productivity of conifer forests by altering hydraulic architecture

    NASA Astrophysics Data System (ADS)

    Alday, Josu; Resco de Dios, Víctor

    2014-05-01

    Predictions of future global climate rely on feedbacks between terrestrial vegetation and the global carbon cycle, but the exact mechanisms underlying this relationship are still being discussed. One of the key knowledge gaps lies on the scaling of cellular processes to the ecosystem level. Here we examine whether an under-explored plant trait, inter-specific variation in the bulk amount of DNA in unreplicated somatic cells (2C DNA content), can explain inter-specific variation in the maximum productivity of conifer forests. We expected 2C DNA content to be negatively related to conifer productivity because: 1) it is positively correlated with cell volume (which, in turn, potentially affects structural features such as leaf mass area, a strong predictor of photosynthetic capacity); 2) it is positively correlated with stomatal size (with larger stomata leading to lower overall stomatal conductance and, by extension, lower CO2 uptake); and 3) larger genome sizes may reduce P availability in RNA (which has been hypothesized to slow growth). We present the results of regression and independent contrasts in different monospecific forests encompassing a 52º latitudinal gradient, each being dominated by 1 of 35 different conifer species. Contrary to expectations, we observed a positive correlation between genome size and maximum Gross Primary Productivity (R2 = 0.47) and also between genome size maximum tree height (R2 = 0.27). This correlation was apparently driven by the effects of genome size on stem hydraulics, since 2C DNA was positively correlated with wood density (R2 = 0.40) and also with resistance to cavitation (P50, R2 = 0.28). That is, increased genome sizes have a positive effect on the productivity of conifer forests by affecting the vascular tissues to increase their capacity for water transport. Our results shed a new light on the evolution of the vascular system of conifer forests and how they affect ecosystem productivity, and indicate the potential to

  6. Oviposition strategies of conifer seed chalcids in relation to host phenology.

    PubMed

    Rouault, Gaëlle; Turgeon, Jean; Candau, Jean-Noël; Roques, Alain; von Aderkas, Patrick

    2004-10-01

    Insects are considered the most important predators of seed cones, the female reproductive structures of conifers, prior to seed dispersal. Slightly more than 100 genera of insects are known to parasitize conifer seed cones. The most diverse (i.e., number of species) of these genera is Megastigmus (Hymenoptera: Torymidae), which comprises many important seed pests of native and exotic conifers. Seed chalcids, Megastigmus spp., lay eggs inside the developing ovules of host conifers and, until recently, oviposition was believed to occur only in fertilized ovules. Ovule development begins just after pollination, but stops if cells are not fertilized. The morphological stage of cone development at the time of oviposition by seed chalcids has been established for many species; however, knowledge of ovule development at that time has been documented for only one species, M. spermotrophus. Megastigmus spermotrophus oviposits in Douglas-fir ovules after pollination but before fertilization. Unlike the unfertilized ovules, those containing a M. spermotrophus larva continue to develop, whether fertilized or not, stressing the need to broaden our understanding of the insect-plant interactions for this entire genus. To achieve this task, we reviewed the scientific literature and assembled information pertaining to the timing of oviposition and to the pollination and fertilization periods of their respective host(s). More specifically, we were searching for circumstantial evidence that other species of Megastigmus associated with conifers could behave (i.e., oviposit before ovule fertilization) and impact on female gametophyte (i.e., prevent abortion) like M. spermotrophus. The evidence from our compilation suggests that seed chalcids infesting Pinaceae may also oviposit before ovule fertilization, just like M. spermotrophus, whereas those infesting Cupressaceae seemingly oviposit after ovule fertilization. Based on this evidence, we hypothesize that all species of Megastigmus

  7. Oviposition strategies of conifer seed chalcids in relation to host phenology

    NASA Astrophysics Data System (ADS)

    Rouault, Gaëlle; Turgeon, Jean; Candau, Jean-Noël; Roques, Alain; Aderkas, Patrick

    2004-10-01

    Insects are considered the most important predators of seed cones, the female reproductive structures of conifers, prior to seed dispersal. Slightly more than 100 genera of insects are known to parasitize conifer seed cones. The most diverse (i.e., number of species) of these genera is Megastigmus (Hymenoptera: Torymidae), which comprises many important seed pests of native and exotic conifers. Seed chalcids, Megastigmus spp., lay eggs inside the developing ovules of host conifers and, until recently, oviposition was believed to occur only in fertilized ovules. Ovule development begins just after pollination, but stops if cells are not fertilized. The morphological stage of cone development at the time of oviposition by seed chalcids has been established for many species; however, knowledge of ovule development at that time has been documented for only one species, M. spermotrophus. Megastigmus spermotrophus oviposits in Douglas-fir ovules after pollination but before fertilization. Unlike the unfertilized ovules, those containing a M. spermotrophus larva continue to develop, whether fertilized or not, stressing the need to broaden our understanding of the insect plant interactions for this entire genus. To achieve this task, we reviewed the scientific literature and assembled information pertaining to the timing of oviposition and to the pollination and fertilization periods of their respective host(s). More specifically, we were searching for circumstantial evidence that other species of Megastigmus associated with conifers could behave (i.e., oviposit before ovule fertilization) and impact on female gametophyte (i.e., prevent abortion) like M. spermotrophus. The evidence from our compilation suggests that seed chalcids infesting Pinaceae may also oviposit before ovule fertilization, just like M. spermotrophus, whereas those infesting Cupressaceae seemingly oviposit after ovule fertilization. Based on this evidence, we hypothesize that all species of Megastigmus

  8. Some conifer clades contribute substantial amounts of leaf waxes to sedimentary archives

    NASA Astrophysics Data System (ADS)

    Diefendorf, A. F.; Wing, S. L.; Leslie, A. B.; Freeman, K. H.

    2014-12-01

    Leaf waxes (i.e. n-alkanes, n-alkanoic acids) and their carbon isotopes (δ13C) are commonly used to track past changes in the carbon cycle or plant ecophysiology. Previous studies indicated that conifer n-alkane concentrations are lower than in angiosperms and that 13C fractionation during n-alkane synthesis (ɛlipid) is smaller than in angiosperms. These prior studies, however, sampled a limited phylogenetic and geographic subset of conifers, leaving out many important subtropical and Southern Hemisphere groups that were once widespread and common components of fossil assemblages. To expand on previous work, we collected 44 conifer species from the University of California Botanical Garden at Berkeley, capturing all extant conifer families and most extant genera. By collecting all specimens at a common site we attempted to minimize the confounding effects of climate, allowing phylogenetic patterns in the δ13C of leaf waxes to be expressed more strongly. We find that Pinaceae, including many North American species used in previous studies, have very low or no n-alkanes. However, other conifer groups have significant concentrations of n-alkanes, especially the Araucariaceae (Norfolk Island pines), Podocarpaceae (common in the Southern Hemisphere), and many species of Cupressaceae (junipers and relatives). Within the Cupressaceae, we find total n-alkane concentrations are high in subfamilies Cupressoideae and Callitroideae, but significantly lower in the early diverging taxodioid lineages (including bald cypress and redwood). Individual n-alkane chain lengths have a weak phylogenetic signal, except for n-C29 alkane, but when combined using average chain length (ACL), a strong phylogenetic signal emerges. The strong phylogenetic signal in ACL reinforces that it is strongly influenced by factors other than climate. An analysis of ɛlipid indicates a strong phylogenetic signal in which the smallest biosynthetic fractionation occurs in Pinaceae and the largest in

  9. The enigma of effective pathlength for 18O enrichment in leaf water of conifers

    NASA Astrophysics Data System (ADS)

    Roden, J. S.; Kahmen, A.; Buchmann, N. C.; Siegwolf, R. T.

    2013-12-01

    The stable isotopes of oxygen (δ18O) in tree ring cellulose provide valuable proxy information about past environments and climate. Mechanistic models have been used to clarify the important drivers of isotope fractionation and help interpret δ18O variation in tree rings. A critical component to these models is an estimate of leaf water enrichment. However, standard models seldom accurately predict 18O enrichment in conifer needles and Péclet corrections often require effective pathlengths (L) that seem unreasonable from the perspective of needle morphology (>0.5 m). To analyze the potential role of path length on the Péclet effect in conifers we carried out experiments in controlled environment chambers. We exposed seedlings of six species of conifer (Abies alba, Larix decidua, Picea abies, Pinus cembra, P. sylvestris, Taxus bacata), that differ in needle morphology, to four different vapor pressure deficits (VPD), in order to modify transpiration rates (E) and leaf water 18O enrichment. Environmental and δ18O data (leaf, stem and chamber water vapor) were collected to parameterize leaf water models. Cross-sections of needles were sampled for an analysis of needle anatomy. Conifer needles have a single strand of vascular tissue making pathlength determinations through anatomical assessments possible. The six species differed in mesophyll distance (measured from endodermis to epidermis) and cell number, with Pinus and Picea species having the shortest distance and Abies and Taxus the longest (flat needle morphology). Other anatomical measures (transfusion distance, cell size etc.) did not differ significantly. A suberized strip was apparent in the endodermis of all species except Taxus and Abies. Conifer needles have a large proportion (from 0.2 to 0.4) of needle cross-sectional area in vascular tissues that may not be subject to evaporative enrichment. As expected, leaf water δ18O and E responded strongly to VPD and standard models (Craig

  10. The Paleocene Eocene carbon isotope excursion in higher plant organic matter: Differential fractionation of angiosperms and conifers in the Arctic

    NASA Astrophysics Data System (ADS)

    Schouten, Stefan; Woltering, Martijn; Rijpstra, W. Irene C.; Sluijs, Appy; Brinkhuis, Henk; Sinninghe Damsté, Jaap S.

    2007-06-01

    A study of upper Paleocene-lower Eocene (P-E) sediments deposited on the Lomonosov Ridge in the central Arctic Ocean reveals relatively high abundances of terrestrial biomarkers. These include dehydroabietane and simonellite derived from conifers (gymnosperms) and a tetra-aromatic triterpenoid derived from angiosperms. The relative percentage of the angiosperm biomarker of the summed angiosperm + conifer biomarkers was increased at the end of the Paleocene-Eocene thermal maximum (PETM), different when observed with pollen counts which showed a relative decrease in angiosperm pollen. Stable carbon isotopic analysis of these biomarkers shows that the negative carbon isotope excursion (CIE) during the PETM amounts to 3‰ for both conifer biomarkers, dehydroabietane and simonellite, comparable to the magnitude of the CIE inferred from marine carbonates, but significantly lower than the 4.5‰ of the terrestrial C 29n-alkane [M. Pagani, N. Pedentchouk, M. Huber, A. Sluijs, S. Schouten, H. Brinkhuis, J.S. Sinninghe Damsté, G.R. Dickens, and the IODP Expedition 302 Expedition Scientists (2006), Arctic's hydrology during global warming at the Paleocene-Eocene thermal maximum. Nature, 442, 671-675.], which is a compound sourced by both conifers and angiosperms. Conspicuously, the angiosperm-sourced aromatic triterpane shows a much larger CIE of 6‰ and suggests that angiosperms increased in their carbon isotopic fractionation during the PETM. Our results thus indicate that the 4.5‰ C 29n-alkane CIE reported previously represents the average CIE of conifers and angiosperms at this site and suggest that the large and variable CIE observed in terrestrial records may be partly explained by the variable contributions of conifers and angiosperms. The differential response in isotopic fractionation of angiosperms and conifers points to different physiological responses of these vegetation types to the rise in temperature, humidity, and greenhouse gases during the PETM.

  11. Anisotropic nanolaminated CoNiFe cores integrated into microinductors for high-frequency dc-dc power conversion

    NASA Astrophysics Data System (ADS)

    Kim, Jooncheol; Kim, Minsoo; Kim, Jung-Kwun; Herrault, Florian; Allen, Mark G.

    2015-11-01

    This paper presents a rectangular, anisotropic nanolaminated CoNiFe core that possesses a magnetically hard axis in the long geometric axis direction. Previously, we have developed nanolaminated cores comprising tens to hundreds of layers of 300-1000 nm thick metallic alloys (i.e. Ni80Fe20 or Co44Ni37Fe19) based on sequential electrodeposition, demonstrating suppressed eddy-current losses at MHz frequencies. In this work, magnetic anisotropy was induced to the nanolaminated CoNiFe cores by applying an external magnetic field (50-100 mT) during CoNiFe film electrodeposition. The fabricated cores comprised tens to hundreds of layers of 500-1000 nm thick CoNiFe laminations that have the hard-axis magnetic property. Packaged in a 22-turn solenoid test inductor, the anisotropic core showed 10% increased effective permeability and 25% reduced core power losses at MHz operation frequency, compared to an isotropic core of the identical geometry. Operating the anisotropic nanolaminated CoNiFe core in a step-down dc-dc converter (15 V input to 5 V output) demonstrated 81% converter efficiency at a switching frequency of 1.1 MHz and output power of 6.5 W. A solenoid microinductor with microfabricated windings integrated with the anisotropic nanolaminated CoNiFe core was fabricated, demonstrating a constant inductance of 600 nH up to 10 MHz and peak quality factor exceeding 20 at 4 MHz. The performance of the microinductor with the anisotropic nanolaminated CoNiFe core is compared with other previously reported microinductors.

  12. Conifer expansion reduces the competitive ability and herbivore defense of aspen by modifying light environment and soil chemistry.

    PubMed

    Calder, W John; Horn, Kevin J; St Clair, Samuel B

    2011-06-01

    Disturbance patterns strongly influence plant community structure. What remains less clear, particularly at a mechanistic level, is how changes in disturbance cycles alter successional outcomes in plant communities. There is evidence that fire suppression is resulting in longer fire return intervals in subalpine forests and that these lengthened intervals increase competitive interactions between aspen and conifer species. We conducted a field and greenhouse study to compare photosynthesis, growth and defense responses of quaking aspen and subalpine fir regeneration under light reductions and shifts in soil chemistry that occur as conifers increase in dominance. The studies demonstrated that aspen regeneration was substantially more sensitive to light and soil resource limitations than that of subalpine fir. For aspen, light reductions and/or shifts in soil chemistry limited height growth, biomass gain, photosynthesis and the production of defense compounds (phenolic glycosides and condensed tannins). Biomass gain and phenolic glycoside concentrations were co-limited by light reduction and changes in soil chemistry. In contrast, subalpine fir seedlings tended to be more tolerant of low light conditions and showed no sensitivity to changes in soil chemistry. Unlike aspen, subalpine fir increased its root to shoot ratio on conifer soils, which may partially explain its maintenance of growth and defense. The results suggest that increasing dominance of conifers in subalpine forests alters light conditions and soil chemistry in a way that places greater physiological and growth constraints on aspen than subalpine fir, with a likely outcome being more successful recruitment of conifers and losses in aspen cover.

  13. Headwater riparian invertebrate communities associated with red alder and conifer wood and leaf litter in southeastern Alaska

    USGS Publications Warehouse

    LeSage, C.M.; Merritt, R.W.; Wipfli, M.S.

    2005-01-01

    We examined how management of young upland forests in southeastern Alaska affect riparian invertebrate taxa richness, density, and biomass, in turn, potentially influencing food abundance for fish and wildlife. Southeastern Alaska forests are dominated by coniferous trees including Sitka spruce (Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), with mixed stands of red cedar (Thuja plicata Donn.). Red alder (Alnus rubra Bong.) is hypothesized to influence the productivity of young-growth conifer forests and through forest management may provide increased riparian invertebrate abundance. To compare and contrast invertebrate densities between coniferous and alder riparian habitats, leaf litter and wood debris (early and late decay classes) samples were collected along eleven headwater streams on Prince of Wales Island, Alaska, during the summers of 2000 and 2001. Members of Acarina and Collembola were the most abundant taxa collected in leaf litter with alder litter having significantly higher mean taxa richness than conifer litter. Members of Acarina were the most abundant group collected on wood debris and alder wood had significantly higher mean taxa richness and biomass than conifer wood. Alder wood debris in more advanced decay stages had the highest mean taxa richness and biomass, compared to other wood types, while conifer late decay wood debris had the highest densities of invertebrates. The inclusion of alder in young-growth conifer forests can benefit forest ecosystems by enhancing taxa richness and biomass of riparian forest invertebrates. ?? 2005 by the Northwest Scientific Association. All rights reserved.

  14. High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

    NASA Astrophysics Data System (ADS)

    Rhen, Fernando M. F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

    We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4Fe 27.7Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux ( μ0Ms) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μr' ˜475 up to 30 MHz with a quality factor ( Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μr'=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency.

  15. Canopy structure of tropical and sub-tropical rain forests in relation to conifer dominance analysed with a portable LIDAR system

    PubMed Central

    Aiba, Shin-ichiro; Akutsu, Kosuke; Onoda, Yusuke

    2013-01-01

    Background and Aims Globally, conifer dominance is restricted to nutient-poor habitats in colder, drier or waterlogged environments, probably due to competition with angiosperms. Analysis of canopy structure is important for understanding the mechanism of plant coexistence in relation to competition for light. Most conifers are shade intolerant, and often have narrow, deep, conical crowns. In this study it is predicted that conifer-admixed forests have less distinct upper canopies and more undulating canopy surfaces than angiosperm-dominated forests. Methods By using a ground-based, portable light detection and ranging (LIDAR) system, canopy structure was quantified for old-growth evergreen rainforests with varying dominance of conifers along altitudinal gradients (200–3100 m a.s.l.) on tropical and sub-tropical mountains (Mount Kinabalu, Malaysian Borneo and Yakushima Island, Japan) that have different conifer floras. Key Results Conifers dominated at higher elevations on both mountains (Podocarpaceae and Araucariaceae on Kinabalu and Cupressaceae and Pinaceae on Yakushima), but conifer dominance also varied with soil/substrate conditions on Kinabalu. Conifer dominance was associated with the existence of large-diameter conifers. Forests with higher conifer dominance showed a canopy height profile (CHP) more skewed towards the understorey on both Kinabalu and Yakushima. In contrast, angiosperm-dominated forests had a CHP skewed towards upper canopy, except for lowland dipterocarp forests and a sub-alpine scrub dominated by small-leaved Leptospermum recurvum (Myrtaceae) on Kinabalu. Forests with a less dense upper canopy had more undulating outer canopy surfaces. Mixed conifer–angiosperm forests on Yakushima and dipterocarp forests on Kinabalu showed similar canopy structures. Conclusions The results generally supported the prediction, suggesting that lower growth of angiosperm trees (except L. recurvum on Kinabalu) in cold and nutrient-poor environments

  16. A White Spruce Gene Catalog for Conifer Genome Analyses1[W][OA

    PubMed Central

    Rigault, Philippe; Boyle, Brian; Lepage, Pierre; Cooke, Janice E.K.; Bousquet, Jean; MacKay, John J.

    2011-01-01

    Several angiosperm plant genomes, including Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), poplar (Populus trichocarpa), and grapevine (Vitis vinifera), have been sequenced, but the lack of reference genomes in gymnosperm phyla reduces our understanding of plant evolution and restricts the potential impacts of genomics research. A gene catalog was developed for the conifer tree Picea glauca (white spruce) through large-scale expressed sequence tag sequencing and full-length cDNA sequencing to facilitate genome characterizations, comparative genomics, and gene mapping. The resource incorporates new and publicly available sequences into 27,720 cDNA clusters, 23,589 of which are represented by full-length insert cDNAs. Expressed sequence tags, mate-pair cDNA clone analysis, and custom sequencing were integrated through an iterative process to improve the accuracy of clustering outcomes. The entire catalog spans 30 Mb of unique transcribed sequence. We estimated that the P. glauca nuclear genome contains up to 32,520 transcribed genes owing to incomplete, partially sequenced, and unsampled transcripts and that its transcriptome could span up to 47 Mb. These estimates are in the same range as the Arabidopsis and rice transcriptomes. Next-generation methods confirmed and enhanced the catalog by providing deeper coverage for rare transcripts, by extending many incomplete clusters, and by augmenting the overall transcriptome coverage to 38 Mb of unique sequence. Genomic sample sequencing at 8.5% of the 19.8-Gb P. glauca genome identified 1,495 clusters representing highly repeated sequences among the cDNA clusters. With a conifer transcriptome in full view, functional and protein domain annotations clearly highlighted the divergences between conifers and angiosperms, likely reflecting their respective evolutionary paths. PMID:21730200

  17. Mapping and monitoring conifer mortality using remote sensing in the Lake Tahoe Basin

    SciTech Connect

    Macomber, S.A.; Woodcock, C.E. )

    1994-12-01

    A prolonged drought in the western US has resulted in alarming levels of mortality in conifer forests. Satellite remote sensing holds the potential for mapping and monitoring the effects of such environmental changes over large geographic areas in a timely manner. Results from the application of a forest canopy reflectance model using multitemporal Landsat TM imagery and field measurements, indicate conifer mortality can be effectively mapped and inventoried. The test area for this project is the Lake Tahoe Basin Management Unit in the Sierra Nevada of California. The Landsat TM images are from the summers of 1988 and 1991. The Li-Strahler canopy model estimates several forest stand parameters, including tree size and canopy cover for each conifer stand, from reflectance values in satellite imagery. The difference in cover estimates between the dates forms the basis for stratifying stands into mortality classes, which are used as both themes in a map and the basis of the field sampling design. Field measurements from 61 stands collected in the summer of 1992 indicate 15% of the original timber volume in the true fir zone died between 1988 and 1992. The resulting low standard error of 11% for this estimate indicates the utility of these mortality classes for detecting areas of high mortality. Also, the patterns in the estimated mean timber volume loss for each class follow the expected trends. The results of this project are immediately useful for fire hazard management, by providing both estimates of the degree of overall mortality and maps showing its location. They also indicate current remote sensing technology may be useful for monitoring the changes in vegetation that are expected to result from climate change.

  18. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes.

    PubMed

    Eagles-Smith, Collin A; Herring, Garth; Johnson, Branden; Graw, Rick

    2016-05-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  19. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

    USGS Publications Warehouse

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2016-01-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  20. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes.

    PubMed

    Eagles-Smith, Collin A; Herring, Garth; Johnson, Branden; Graw, Rick

    2016-05-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish. PMID:26854697

  1. Nitric acid dry deposition to conifer forests: Niwot Ridge spruce-fir-pine study

    USGS Publications Warehouse

    Sievering, H.; Kelly, T.; McConville, G.; Seibold, C.; Turnipseed, A.

    2001-01-01

    The dry deposition velocity of nitric acid, Vd(HNO3), over a 12-m (mean height) spruce-fir forest at Niwot Ridge, Colorado was estimated during 13 daytime periods using the flux-gradient approach. Turbulence intensity at this site is high (mean u* of 0.65ms-1 with u of 2.9ms-1) and contributed to the large observed Vd(HNO3). The overriding contributor is identified to be the small aerodynamic needle width of the conifer trees. Two cases had inflated Vd(HNO3) due to height-differentiated nitric acid loss to soil-derived particle surfaces. Not considering these cases, the mean Vd(HNO3) was 7.6cms-1. The mean laminar boundary layer resistance (Rb) was found to be 7.8sm-1 (of similar magnitude to that of the aerodynamic resistance, 8.5sm-1). The data-determined Rb is bracketed by two theoretical estimates of the mean Rb, 5.9 and 8.6sm-1, that include consideration of the small canopy length scale (aerodynamic needle width), 1mm or less, at this conifer forest. However, the poor correlation of data-determined Rb values with both sets of theoretical estimates indicates that measurement error needs to be reduced and/or improved formulations of theoretical Rb values are in order. The large observed Vd(HNO3) at this conifer forest site is attributed to high turbulence intensity, and, especially, to small aerodynamic needle width. Copyright ?? 2001 Elsevier Science Ltd.

  2. Wildlife species associated with non-coniferous vegetation in Pacific Northwest conifer forests: A review

    USGS Publications Warehouse

    Hagar, J.C.

    2007-01-01

    Non-coniferous vegetation, including herbs, shrubs, and broad-leaved trees, makes a vital contribution to ecosystem function and diversity in Pacific Northwest conifer forests. However, forest management has largely been indifferent or detrimental to shrubs and trees that have low commercial value, in spite of a paradigm shift towards more holistic management in recent decades. Forest management practices that are detrimental to broad-leaved trees and shrubs are likely to decrease habitat diversity for wildlife, but the number of species that may be affected has not previously been enumerated. I reviewed life history accounts for forest-dwelling vertebrate wildlife species and derived a list of 78 species in Oregon and Washington that are associated with non-coniferous vegetation. The diversity of direct and indirect food resources provided was the primary functional basis for associations of most species with non-coniferous vegetation. Thus, a diversity of herbs and broad-leaved trees and shrubs provides the foundation for food webs that contribute to diversity at multiple trophic levels in Pacific Northwest conifer forests. Given the number of species associated with non-coniferous vegetation in conifer-dominated forests, maintaining habitats that support diverse plant communities, particularly broad-leaved trees and shrubs, will be an important component of management strategies intended to foster biodiversity. Silvicultural practices such as modified planting densities, and pre-commercial and commercial thinning, can be used to control stand density in order to favor the development of understory herbs, shrubs, and a diversity of tree species within managed stands. Allowing shrubs and hardwood trees to develop and persist in early seral stands by curtailing vegetation control also would benefit many species associated with non-coniferous vegetation.

  3. Quantifying thermal constraints on carbon and water fluxes in a mixed-conifer sky island ecosystem

    NASA Astrophysics Data System (ADS)

    Braun, Z.; Minor, R. L.; Potts, D. L.; Barron-Gafford, G. A.

    2012-12-01

    Western North American forests represent a potential, yet uncertain, sink for atmospheric carbon. Revealing how predicted climatic conditions of warmer temperatures and longer inter-storm periods of moisture stress might influence the carbon status of these forests requires a fuller understanding of plant functional responses to abiotic stress. While data related to snow dominated montane ecosystems has become more readily available to parameterize ecosystem function models, there is a paucity of data available for Madrean sky island mixed-conifer forests, which receive about one third of their precipitation from the North American Monsoon. Thus, we quantified ecophysiological responses to moisture and temperature stress in a Madrean mixed-conifer forest near Tucson, Arizona, within the footprint of the Mt. Bigelow Eddy Covariance Tower. In measuring a series of key parameters indicative of carbon and water fluxes within the dominant species across pre-monsoon and monsoon conditions, we were able to develop a broader understanding of what abiotic drivers are most restrictive to plant performance in this ecosystem. Within Pinus ponderosa (Ponderosa Pine), Pseudotsuga menziesii (Douglas Fir), and Pinus strobiformis (Southwestern White Pine) we quantified: (i) the optimal temperature (Topt) for maximum photosynthesis (Amax), (ii) the range of temperatures over which photosynthesis was at least 50% of Amax (Ω50), and (iii) each conifer's water use efficiency (WUE) to relate to the balance between carbon uptake and water loss in this high elevation semiarid ecosystem. Our findings support the prediction that photosynthesis decreases under high temperatures (>30°C) among the three species we measured, regardless of soil moisture status. However, monsoon moisture reduced sensitivity to temperature extremes and fluctuations (Ω50), which substantially magnified total photosynthetic productivity. In particular, wet conditions enhanced Amax the most dramatically for P

  4. Development of nuclear and chloroplast microsatellite markers for the endangered conifer Callitris sulcata (Cupressaceae)1

    PubMed Central

    Sakaguchi, Shota; Lannuzel, Guillaume; Fogliani, Bruno; Wulff, Adrien S.; L’Huillier, Laurent; Kurata, Seikan; Ueno, Saneyoshi; Isagi, Yuji; Tsumura, Yoshihiko; Ito, Motomi

    2015-01-01

    Premise of the study: Microsatellite markers were developed for Callitris sulcata (Cupressaceae), an endangered conifer species in New Caledonia. Methods and Results: Using sequencing by synthesis (SBS) of an RNA-Seq library, 15 polymorphic nuclear and chloroplast microsatellite markers were developed. When evaluated with 48 individuals, these markers showed genetic variations ranging from two to 15 alleles and expected heterozygosity ranging from 0 to 0.881. Conclusions: These markers will be useful for examining the genetic diversity and structure of remaining wild populations and improving the genetic status of ex situ populations. PMID:26312198

  5. Measuring near infrared spectral reflectance changes from water stressed conifer stands with AIS-2

    NASA Technical Reports Server (NTRS)

    Riggs, George; Running, Steven W.

    1987-01-01

    Airborne Imaging Spectrometer-2 (AIS-2) data was acquired over two paired conifer stands for the purpose of detecting differences in spectral reflectance between stressed and natural canopies. Water stress was induced in a stand of Norway spruce and white pine by severing the sapwood near the ground. Water stress during the AIS flights was evaluated through shoot water potential and relative water content measurements. Preliminary analysis with raw AIS-2 data using SPAM indicates that there were small, inconsistent differences in absolute spectral reflectance in the near infrared 0.97 to 1.3 micron between the stressed and natural canopies.

  6. Molecular Characterization of Fusarium oxysporum and Fusarium commune Isolates from a Conifer Nursery.

    PubMed

    Stewart, Jane E; Kim, Mee-Sook; James, Robert L; Dumroese, R Kasten; Klopfenstein, Ned B

    2006-10-01

    ABSTRACT Fusarium species can cause severe root disease and damping-off in conifer nurseries. Fusarium inoculum is commonly found in most container and bareroot nurseries on healthy and diseased seedlings, in nursery soils, and on conifer seeds. Isolates of Fusarium spp. can differ in virulence; however, virulence and colony morphology are not correlated. Forty-one isolates of Fusarium spp., morphologically indistinguishable from F. oxysporum, were collected from nursery samples (soils, healthy seedlings, and diseased seedlings). These isolates were characterized by amplified fragment length polymorphism (AFLP) and DNA sequencing of nuclear rDNA (internal transcribed spacer including 5.8S rDNA), mitochon-drial rDNA (small subunit [mtSSU]), and nuclear translation elongation factor 1-alpha. Each isolate had a unique AFLP phenotype. Out of 121 loci, 111 (92%) were polymorphic; 30 alleles were unique to only highly virulent isolates and 33 alleles were unique to only isolates nonpathogenic on conifers. Maximum parsimony and Bayesian analyses of DNA sequences from all three regions and the combined data set showed that all highly virulent isolates clearly separated into a common clade that contained F. commune, which was recently distinguished from its sister taxon, F. oxysporum. Interestingly, all but one of the nonpathogenic isolates grouped into a common clade and were genetically similar to F. oxysporum. The AFLP cladograms had similar topologies when compared with the DNA-based phylograms. Although all tested isolates were morphologically indistinguishable from F. oxysporum based on currently available monographs, some morphological traits can be plastic and unreliable for identification of Fusarium spp. We consider the highly virulent isolates to be F. commune based on strong genetic evidence. To our knowledge, this is the first reported evidence that shows F. commune is a cause of Fusarium disease (root rot and dampingoff) on Douglas-fir seedlings. Furthermore

  7. Fuel models to predict fire behavior in untreated conifer slash. Forest Service research note (final)

    SciTech Connect

    Salazar, L.A.; Bevins, C.D.

    1984-11-01

    Fire behavior in untreated slash of nine conifer species was simulated for 10 successive years after logging. Two aging factors that affect fire behavior--fuel bed compaction and foliage retention--were modeled by least squares regression techniques. On the basis of spread rate and flame length for a set of weather observations, standard Northern Forest Fire Laboratory fuel models were chosen to predict fire behavior for aging slash of each species at three initial fuel loadings. Differences in the standard fuel model sequences best representing aging process among species were most influenced by foliage surface-area-to-volume ratio, and such differences increased as initial fuel load increased.

  8. Temperature effects on nitrogen form uptake by seedling roots of three contrasting conifers.

    PubMed

    Boczulak, S A; Hawkins, B J; Roy, R

    2014-05-01

    Plant species may show a preference for uptake of particular nitrogen (N) forms, but little is known about how N form preference is influenced by soil temperature. Potential future changes in soil N form availability and plant N form preference in warmer soils might shift competitive interactions among forest tree species. We compared the N uptake and growth of three conifer species from contrasting environments grown at rhizosphere temperatures of 10, 16 or 20 °C and supplied with ammonium (NH4 (+)) or nitrate (NO3 (-)) or a mix of arginine and alanine. Short-term N uptake was assessed using ion-selective microelectrodes and application of (15)N, and long-term uptake was assessed by plant N status. Species exhibited preferences for particular N forms, and these preferences related to the N form most available in native soils. Specifically, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) showed a preference for nitrate (a N form commonly found in warmer areas), Sitka spruce (Picea sitchensis (Bong.) Carr.) preferred ammonium (a N form abundant in cold soils) and Engelmann spruce (Picea engelmannii Parry ex Engelm.) showed a preference for ammonium and organic N (organic N is often abundant in cold soils). Relative N form preference, as indicated by plant growth, changed with temperature in some species, indicating that these species could acclimate to changing rhizosphere temperatures. Understanding how conifers utilize available soil nutrients at different temperatures can help to predict species' future performance as soil temperatures rise. PMID:24831958

  9. Expression Divergence Is Correlated with Sequence Evolution but Not Positive Selection in Conifers.

    PubMed

    Hodgins, Kathryn A; Yeaman, Sam; Nurkowski, Kristin A; Rieseberg, Loren H; Aitken, Sally N

    2016-06-01

    The evolutionary and genomic determinants of sequence evolution in conifers are poorly understood, and previous studies have found only limited evidence for positive selection. Using RNAseq data, we compared gene expression profiles to patterns of divergence and polymorphism in 44 seedlings of lodgepole pine (Pinus contorta) and 39 seedlings of interior spruce (Picea glauca × engelmannii) to elucidate the evolutionary forces that shape their genomes and their plastic responses to abiotic stress. We found that rapidly diverging genes tend to have greater expression divergence, lower expression levels, reduced levels of synonymous site diversity, and longer proteins than slowly diverging genes. Similar patterns were identified for the untranslated regions, but with some exceptions. We found evidence that genes with low expression levels had a larger fraction of nearly neutral sites, suggesting a primary role for negative selection in determining the association between evolutionary rate and expression level. There was limited evidence for differences in the rate of positive selection among genes with divergent versus conserved expression profiles and some evidence supporting relaxed selection in genes diverging in expression between the species. Finally, we identified a small number of genes that showed evidence of site-specific positive selection using divergence data alone. However, estimates of the proportion of sites fixed by positive selection (α) were in the range of other plant species with large effective population sizes suggesting relatively high rates of adaptive divergence among conifers. PMID:26873578

  10. Specialised emission pattern of leaf trace in a late Permian (253 million-years old) conifer

    PubMed Central

    Wei, Hai-Bo; Feng, Zhuo; Yang, Ji-Yuan; Chen, Yu-Xuan; Shen, Jia-Jia; He, Xiao-Yuan

    2015-01-01

    Leaf traces are important structures in higher plants that connect leaves and the stem vascular system. The anatomy and emission pattern of leaf traces are well studied in extant vascular plants, but remain poorly understood in fossil lineages. We quantitatively analysed the leaf traces in the late Permian conifer Ningxiaites specialis from Northwest China based on serial sections through pith, primary and secondary xylems. A complete leaf traces emission pattern of a conifer is presented for the first time from the late Palaeozoic. Three to five monarch leaf traces are grouped in clusters, arranged in a helical phyllotaxis. The leaf traces in each cluster can be divided into upper, middle and lower portions, and initiate at the pith periphery and cross the wood horizontally. The upper leaf trace increases its diameter during the first growth increment and then diminishes completely, which indicates leaf abscission at the end of the first year. The middle trace immediately bifurcates once or twice to form two or three vascular bundles. The lower trace persists as a single bundle during its entire length. The intricate leaf trace dynamics indicates this fossil plant had a novel evolutionary habit by promoting photosynthetic capability for the matured plant. PMID:26198410

  11. Conifer species adapt to low-rainfall climates by following one of two divergent pathways.

    PubMed

    Brodribb, Timothy J; McAdam, Scott A M; Jordan, Gregory J; Martins, Samuel C V

    2014-10-01

    Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here we combine distributional, climatic, and physiological evidence from 42 species of conifers to show that the evolution of drought resistance follows two distinct pathways, both involving the coordinated evolution of tissues regulating water supply (xylem) and water loss (stomatal pores) in leaves. Only species with very efficient stomatal closure, and hence low minimum rates of water loss, inhabit dry habitats, but species diverged in their apparent mechanism for maintaining closed stomata during drought. An ancestral mechanism found in Pinaceae and Araucariaceae species relies on high levels of the hormone abscisic acid (ABA) to close stomata during water stress. A second mechanism, found in the majority of Cupressaceae species, uses leaf desiccation rather than high ABA levels to close stomata during sustained water stress. Species in the latter group were characterized by xylem tissues with extreme resistance to embolism but low levels of foliar ABA after 30 d without water. The combination of low levels of ABA under stress with cavitation-resistant xylem enables these species to prolong stomatal opening during drought, potentially extending their photosynthetic activity between rainfall events. Our data demonstrate a surprising simplicity in the way conifers evolved to cope with water shortage, indicating a critical interaction between xylem and stomatal tissues during the process of evolution to dry climates. PMID:25246559

  12. Long-term effects of fire severity on oak-conifer dynamics in the southern Cascades.

    PubMed

    Cocking, Matthew I; Varner, J Morgan; Knapp, Eric E

    2014-01-01

    We studied vegetation composition and structure in a mixed conifer-oak ecosystem across a range of fire severity 10 years following wildfire. Sample plots centered on focal California black oaks (Quercus kelloggii) were established to evaluate oak and neighboring tree and shrub recovery across a gradient of fire severity in the southern Cascade Range, USA. Shrub and oak resprouting was strongest around focal oaks where conifer mortality was greatest. Linear modeling revealed negative relationships between California black oak sprout height or basal area and residual overstory tree survival, primarily white fir (Abies concolor). The two dominant competing species, California black oak and white fir, showed opposite responses to fire severity. Sprouting California black oak and associated shrubs dominated in severely burned areas, while surviving, non-sprouting white fir maintained dominance by its height advantage and shading effects in areas that burned with low fire severity. Our results indicate that high-severity fire promotes persistence and restoration of ecosystems containing resprouting species, such as California black oak, that are increasingly rare due to widespread fire exclusion in landscapes that historically experienced more frequent fire. We present a conceptual model based on our results and supported by a synthesis of postfire resprouting dynamics literature. Our results and conceptual model help illuminate long-term postfire vegetation responses and the potential ability of fire to catalyze formation of alternate vegetation community structures that may not be apparent in studies that evaluate postfire effects at shorter time-since-fire intervals or at coarser scales.

  13. Spectral changes in conifers subjected to air pollution and water stress: Experimental studies

    NASA Technical Reports Server (NTRS)

    Westman, Walter E.; Price, Curtis V.

    1988-01-01

    The roles of leaf anatomy, moisture and pigment content, and number of leaf layers on spectral reflectance in healthy, pollution-stressed, and water-stressed conifer needles were examined experimentally. Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were exposed to ozone and acid mist treatments in fumigation chambers; red pine (Pinus resinosa) needles were artificially dried. Infrared reflectance from stacked needles rose with free water loss. In an air-drying experiment, cell volume reductions induced by loss of turgor caused near-infrared reflectance (TM band 4) to drop after most free water was lost. Under acid mist fumigation, stunting of tissue development similarly reduced band 4 reflectance. Both artificial drying and pollutant fumigation caused a blue shift of the red edge of spectral reflectance curves in conifers, attributable to chlorophyll denaturation. Thematic mapper band ratio 4/3 fell and 5/4 rose with increasing pollution stress on artificial drying. Loss of water by air-drying, freeze-drying, or oven-drying enhanced spectral features, due in part to greater scattering and reduced water absorption. Grinding of the leaf tissue further enhanced the spectral features by increasing reflecting surfaces and path length. In a leaf-stacking experiment, an asymptote in visible and infrared reflectance was reached at 7-8 needle layers of red pine.

  14. Conifer species adapt to low-rainfall climates by following one of two divergent pathways

    PubMed Central

    Brodribb, Timothy J.; McAdam, Scott A.M.; Jordan, Gregory J.; Martins, Samuel C.V.

    2014-01-01

    Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here we combine distributional, climatic, and physiological evidence from 42 species of conifers to show that the evolution of drought resistance follows two distinct pathways, both involving the coordinated evolution of tissues regulating water supply (xylem) and water loss (stomatal pores) in leaves. Only species with very efficient stomatal closure, and hence low minimum rates of water loss, inhabit dry habitats, but species diverged in their apparent mechanism for maintaining closed stomata during drought. An ancestral mechanism found in Pinaceae and Araucariaceae species relies on high levels of the hormone abscisic acid (ABA) to close stomata during water stress. A second mechanism, found in the majority of Cupressaceae species, uses leaf desiccation rather than high ABA levels to close stomata during sustained water stress. Species in the latter group were characterized by xylem tissues with extreme resistance to embolism but low levels of foliar ABA after 30 d without water. The combination of low levels of ABA under stress with cavitation-resistant xylem enables these species to prolong stomatal opening during drought, potentially extending their photosynthetic activity between rainfall events. Our data demonstrate a surprising simplicity in the way conifers evolved to cope with water shortage, indicating a critical interaction between xylem and stomatal tissues during the process of evolution to dry climates. PMID:25246559

  15. A multiproxy environmental investigation of Holocene wood from a submerged conifer forest in Lake Huron, USA

    NASA Astrophysics Data System (ADS)

    Hunter, R. Douglas; Panyushkina, Irina P.; Leavitt, Steven W.; Wiedenhoeft, Alex C.; Zawiskie, John

    2006-07-01

    Remains of a Holocene drowned forest in southern Lake Huron discovered in 12.5 m of water (164 m above sea level), 4.5 km east of Lexington, Michigan USA (Sanilac site), provided wood to investigate environment and lake history using several proxies. Macrofossil evidence indicates a forest comprised primarily of conifers equivalent to the modern "rich conifer swamp" community, despite generally low regional abundance of these species in pollen records. Ages range from 7095 ± 50 to 6420 ± 70 14C yr BP, but the clustering of stump dates and the development of 2 floating tree-ring chronologies suggest a briefer forest interval of no more than c. 400 years. Dendrochronological analysis indicates an environment with high inter-annual climate variability. Stable-carbon isotope composition falls within the range of modern trees from this region, but the stable-oxygen composition is consistent with warmer conditions than today. Both our tree-ring and isotope data provide support for a warmer environment in this region, consistent with a mid-Holocene thermal maximum. This drowned forest also provides a dated elevation in the Nipissing transgression at about 6420 14C yr BP (7350 cal yr BP) in the southern Lake Huron basin, a few hundred years before reopening of the St. Clair River drainage.

  16. Foliage influences forced convection heat transfer in conifer branches and buds.

    PubMed

    Michaletz, S T; Johnson, E A

    2006-01-01

    Conifer foliage structures affect branch and bud temperature by altering the development and convective resistance of the thermal boundary layer. This paper examines foliage effects on forced convection in branches and buds of Picea glauca (Moench) Voss and Pinus contorta Dougl. Ex. Loud., two species that represent the range of variation in foliage structure among conifers. Forced convection is characterized by a power law relating Nusselt (heat transfer) and Reynolds (boundary layer development) numbers. Data were collected in a laminar flow wind tunnel for free stream velocities of 0.16-6.95 m s(-1). Scaling parameters were compared against literature values for silver cast branch replicas, a bed of real foliage, cylinders, and tube banks. Foliage structures reduced Nusselt numbers (heat transfer) relative to cylinders, which are typically used to approximate leafless branches and buds. Significantly different scaling relationships were observed for all foliage structures considered. Forced convection scaling relationships varied with foliage structure. The scaling relationships reported here account for variation within populations of branches and buds and can be used to characterize forced convection in a forest canopy.

  17. Conifer species adapt to low-rainfall climates by following one of two divergent pathways.

    PubMed

    Brodribb, Timothy J; McAdam, Scott A M; Jordan, Gregory J; Martins, Samuel C V

    2014-10-01

    Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here we combine distributional, climatic, and physiological evidence from 42 species of conifers to show that the evolution of drought resistance follows two distinct pathways, both involving the coordinated evolution of tissues regulating water supply (xylem) and water loss (stomatal pores) in leaves. Only species with very efficient stomatal closure, and hence low minimum rates of water loss, inhabit dry habitats, but species diverged in their apparent mechanism for maintaining closed stomata during drought. An ancestral mechanism found in Pinaceae and Araucariaceae species relies on high levels of the hormone abscisic acid (ABA) to close stomata during water stress. A second mechanism, found in the majority of Cupressaceae species, uses leaf desiccation rather than high ABA levels to close stomata during sustained water stress. Species in the latter group were characterized by xylem tissues with extreme resistance to embolism but low levels of foliar ABA after 30 d without water. The combination of low levels of ABA under stress with cavitation-resistant xylem enables these species to prolong stomatal opening during drought, potentially extending their photosynthetic activity between rainfall events. Our data demonstrate a surprising simplicity in the way conifers evolved to cope with water shortage, indicating a critical interaction between xylem and stomatal tissues during the process of evolution to dry climates.

  18. Causes and consequences of variation in conifer leaf life-span

    SciTech Connect

    Reich, P.B.; Koike, T.; Gower, S.T.; Schoettle, A.W.

    1995-07-01

    Species with mutually supporting traits, such as high N{sub mass}, SLA, and A{sub mass}, and short leaf life-span, tend to inhabit either generally resource-rich environments or spatial and/or temporal microhabitats that are resource-rich in otherwise more limited habitats (e.g., {open_quotes}precipitation{close_quotes} ephemerals in warm deserts or spring ephemerals in the understory of temperate deciduous forests). In contrast, species with long leaf life-span often support foliage with low SLA, N{sub mass}, and A{sub mass}, and often grow in low-temperature limited, dry, and/or nutrient-poor environments. The contrast between evergreen and deciduous species, and the implications that emerge from such comparisons, can be considered a paradigm of modern ecological theory. However, based on the results of Reich et al. (1992) and Gower et al. (1993), coniferous species with foliage that persists for 9-10 years are likely to assimilate and allocate carbon and nutrients differently than other evergreen conifers that retain foliage for 2-3 years. Thus, attempts to contrast ecophysiological or ecosystem characteristics of evergreen versus deciduous life forms may be misleading, and pronounced differences among evergreen conifers may be ignored. Clearly, the deciduous-evergreen contrast, although useful in several ways, should be viewed from the broader perspective of a gradient in leaf life-span.

  19. Analysis of freeze-thaw embolism in conifers. The interaction between cavitation pressure and tracheid size.

    PubMed

    Pittermann, Jarmila; Sperry, John S

    2006-01-01

    Ice formation in the xylem sap produces air bubbles that under negative xylem pressures may expand and cause embolism in the xylem conduits. We used the centrifuge method to evaluate the relationship between freeze-thaw embolism and conduit diameter across a range of xylem pressures (Px) in the conifers Pinus contorta and Juniperus scopulorum. Vulnerability curves showing loss of conductivity (embolism) with Px down to -8 MPa were generated with versus without superimposing a freeze-thaw treatment. In both species, the freeze-thaw plus water-stress treatment caused more embolism than water stress alone. We estimated the critical conduit diameter (Df) above which a tracheid will embolize due to freezing and thawing and found that it decreased from 35 microm at a Px of -0.5 MPa to 6 microm at -8 MPa. Further analysis showed that the proportionality between diameter of the air bubble nucleating the cavitation and the diameter of the conduit (kL) declined with increasingly negative Px. This suggests that the bubbles causing cavitation are smaller in proportion to tracheid diameter in narrow tracheids than in wider ones. A possible reason for this is that the rate of dissolving increases with bubble pressure, which is inversely proportional to bubble diameter (La Place's law). Hence, smaller bubbles shrink faster than bigger ones. Last, we used the empirical relationship between Px and Df to model the freeze-thaw response in conifer species.

  20. Control of resin production in Araucaria angustifolia, an ancient South American conifer.

    PubMed

    Perotti, J C; da Silva Rodrigues-Corrêa, K C; Fett-Neto, A G

    2015-07-01

    Araucaria angustifolia is an ancient slow-growing conifer that characterises parts of the Southern Atlantic Forest biome, currently listed as a critically endangered species. The species also produces bark resin, although the factors controlling its resinosis are largely unknown. To better understand this defence-related process, we examined the resin exudation response of A. angustifolia upon treatment with well-known chemical stimulators used in fast-growing conifers producing both bark and wood resin, such as Pinus elliottii. The initial hypothesis was that A. angustifolia would display significant differences in the regulation of resinosis. The effect of Ethrel(®) (ET - ethylene precursor), salicylic acid (SA), jasmonic acid (JA), sulphuric acid (SuA) and sodium nitroprusside (SNP - nitric oxide donor) on resin yield and composition in young plants of A. angustifolia was examined. In at least one of the concentrations tested, and frequently in more than one, an aqueous glycerol solution applied on fresh wound sites of the stem with one or more of the adjuvants examined promoted an increase in resin yield, as well as monoterpene concentration (α-pinene, β-pinene, camphene and limonene). Higher yields and longer exudation periods were observed with JA and ET, another feature shared with Pinus resinosis. The results suggest that resinosis control is similar in Araucaria and Pinus. In addition, A. angustifolia resin may be a relevant source of valuable terpene chemicals, whose production may be increased by using stimulating pastes containing the identified adjuvants.

  1. Stable Water Use Efficiency under Climate Change of Three Sympatric Conifer Species at the Alpine Treeline

    PubMed Central

    Wieser, Gerhard; Oberhuber, Walter; Gruber, Andreas; Leo, Marco; Matyssek, Rainer; Grams, Thorsten Erhard Edgar

    2016-01-01

    The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies, and Larix decidua trees from 1975 to 2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE) of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ13C and Δ18O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI) suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species. PMID:27375653

  2. Stable Water Use Efficiency under Climate Change of Three Sympatric Conifer Species at the Alpine Treeline.

    PubMed

    Wieser, Gerhard; Oberhuber, Walter; Gruber, Andreas; Leo, Marco; Matyssek, Rainer; Grams, Thorsten Erhard Edgar

    2016-01-01

    The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies, and Larix decidua trees from 1975 to 2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE) of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ(13)C and Δ(18)O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI) suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species.

  3. Temperature stress tolerance of conifer seedlings after exposure to UV-B radiation.

    PubMed

    L'Hirondelle, Sylvia J; Binder, Wolfgang D

    2005-01-01

    Ground-level UV-B radiation has increased globally due to a thinning stratospheric ozone layer. We estimated the effects of increased UV-B on 10 conifer species grown in chambers in greenhouses with supplemental UV-B. Species were selected from a wide range of geographic locations. Plant material of two ages (germinants, first growing season; seedlings, second season) were exposed to three levels of UV-B from ambient (at Victoria, B.C., Canada) to three times ambient (12 kJ m(-2) d(-1)) for up to four months. Frost hardiness and heat tolerance of shoots were estimated from changes in chlorophyll fluorescence after exposure to test temperatures. There were no significant differences among seed sources from different elevations in their response to temperature stresses. When UV-B increased above the ambient level, three species (interior Douglas-fir, Engelmann spruce, and interior lodgepole pine) increased in frost hardiness and four (grand fir, interior spruce, yellow-cedar, and western redcedar) decreased. Two species (western redcedar and western hemlock) increased in heat tolerance when UV-B increased to the 12 kJ level. The main differences in stress tolerance were between the triple ambient and the other two treatments, not between ambient and double ambient, suggesting that any changes in UV-B would have to be large to elicit physiological changes in conifer seedlings.

  4. Three causes of variation in the photochemical reflectance index (PRI) in evergreen conifers.

    PubMed

    Wong, Christopher Y S; Gamon, John A

    2015-04-01

    The photochemical reflectance index (PRI) reflects diurnal xanthophyll cycle activity and is also influenced by seasonally changing carotenoid : Chl pigment ratios. Both changing pigment pools and xanthophyll cycle activity contribute to photoprotection in evergreen conifers exposed to boreal winters, but they operate over different timescales, and their relative contribution to the PRI signal has often been unclear. To clarify these responses and their contribution to the PRI signal, leaf PRI, pigment composition, temperature and irradiance were monitored over 2 yr for two evergreen conifers (Pinus contorta and Pinus ponderosa) in a boreal climate. PRI was affected by three distinct processes operating over different timescales and exhibiting contrasting spectral responses. Over the 2 yr study period, the greatest change in PRI resulted from seasonally changing carotenoid : Chl pigment ratios, followed by a previously unreported shifting leaf albedo during periods of deep cold. Remarkably, the smallest change was attributable to the xanthophyll cycle. To properly distinguish these three effects, interpretation of PRI must consider temporal context, physiological responses to evolving environmental conditions, and spectral response. Consideration of the separate mechanisms affecting PRI over different timescales could greatly improve efforts to monitor changing photosynthetic activity using optical remote sensing. PMID:25408288

  5. Acid mist and ozone effects on the leaf chemistry of two western conifer species

    NASA Technical Reports Server (NTRS)

    Westman, Walter E.; Temple, Patrick J.

    1989-01-01

    The effects of ozone and acid-mist exposures on the leaf chemistry of Jeffrey pine and giant sequoia seedlings grown in filtered-air greenhouses were investigated. Acid-mist treatments (pH 4.1, 3.4, 2.7, or 2.0) were administered for 3 h, and ozone exposures (0, 0.10, and 0.20 microliter/liter), which followed acid-mist treatments, for 4 h, each for three days a week for six to nine weeks. It was found that seedlings were more susceptible to acid-mist and acid mist/ozone combinations, than to ozone alone. Acid mist treatment resulted in higher levels of nitrogen and sulfur (both present in acid mist) as well as Na. Leaves of giant sequoia exhibited increased K and decreased Mn, while Jeffrey pine showed increases in Fe and Mn. In sequoia leaves, concentrations of Ca, Mg, and Ba decreased. Acid treatment also reduced chlorophyll b concentrations in both conifer species. Extensive changes induced by acid mist are consistent with earlier observations of changes in spectral reflectance of conifer seedlings observed after three weeks of fumigation.

  6. Damping-off in conifer seedling nurseries in Noshahr and Kelardasht.

    PubMed

    Zad, S J; Koshnevice, M

    2001-01-01

    To study the damping-off of conifer seedlings, we have collected samples from the roots of conifer seedlings (Pinus nigra, Picea excelsa, Abieces spp, Cupressus arizonica, Cupressus sempervirens) from nurseries in the south of Iran (Noshahr and Kelardasht). After disinfecting the samples, we have used standard media like PDA, MA and CLA. The following fungi were identified: Fusarium solani, Fusarium oxysporum, Fusarium sambucinum, Clamydosporium, Rhizoctonia solani, Cylindrocarpon spp., Alternaria spp, Macrophomina phaseoli. Amongst the above mentioned fungi, Fusarium spp. were the commonest ones. Pathogenecity tests of Fusarium spp. and Rhizoctonia solani on seedlings were done. Isolated fungal colonies were purified using single mycelium and single spore methods. Fungal isolates were identified after subculturing on PDA and CLA media by Nelson method. These isolates were Fusarium solani, F. oxysporium, F. sambucinum and F. clamydosporum. Other fungal isolates were Rhizoctonia spp. In order to determine the infectivity of Fusarium on their hosts, seeds of Pinus nigra, Cupressus arizonica and Cupressus sempervirens var. horizontalis were cultured in four repetitions each containing 2 seedlings. After a seasonal growth, seedlings were inoculated with a suspension of Fusarium spores (4.5 +/- 0.3 x 1016 spore/ml). Infection of P. nigra, Cupressus arizonica and Cupressus sempervirens var. horizontalis with F. solani and Pinus nigra and Cupressus semperivirens var. horizontalis with F. oxysporum was high whereas that of Cupressus arizonica with F. sambucinum, F. mondiforme and F. clamydosporum was moderate.

  7. Stable Water Use Efficiency under Climate Change of Three Sympatric Conifer Species at the Alpine Treeline.

    PubMed

    Wieser, Gerhard; Oberhuber, Walter; Gruber, Andreas; Leo, Marco; Matyssek, Rainer; Grams, Thorsten Erhard Edgar

    2016-01-01

    The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies, and Larix decidua trees from 1975 to 2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE) of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ(13)C and Δ(18)O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI) suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species. PMID:27375653

  8. Improved white spruce (Picea glauca) genome assemblies and annotation of large gene families of conifer terpenoid and phenolic defense metabolism.

    PubMed

    Warren, René L; Keeling, Christopher I; Yuen, Macaire Man Saint; Raymond, Anthony; Taylor, Greg A; Vandervalk, Benjamin P; Mohamadi, Hamid; Paulino, Daniel; Chiu, Readman; Jackman, Shaun D; Robertson, Gordon; Yang, Chen; Boyle, Brian; Hoffmann, Margarete; Weigel, Detlef; Nelson, David R; Ritland, Carol; Isabel, Nathalie; Jaquish, Barry; Yanchuk, Alvin; Bousquet, Jean; Jones, Steven J M; MacKay, John; Birol, Inanc; Bohlmann, Joerg

    2015-07-01

    White spruce (Picea glauca), a gymnosperm tree, has been established as one of the models for conifer genomics. We describe the draft genome assemblies of two white spruce genotypes, PG29 and WS77111, innovative tools for the assembly of very large genomes, and the conifer genomics resources developed in this process. The two white spruce genotypes originate from distant geographic regions of western (PG29) and eastern (WS77111) North America, and represent elite trees in two Canadian tree-breeding programs. We present an update (V3 and V4) for a previously reported PG29 V2 draft genome assembly and introduce a second white spruce genome assembly for genotype WS77111. Assemblies of the PG29 and WS77111 genomes confirm the reconstructed white spruce genome size in the 20 Gbp range, and show broad synteny. Using the PG29 V3 assembly and additional white spruce genomics and transcriptomics resources, we performed MAKER-P annotation and meticulous expert annotation of very large gene families of conifer defense metabolism, the terpene synthases and cytochrome P450s. We also comprehensively annotated the white spruce mevalonate, methylerythritol phosphate and phenylpropanoid pathways. These analyses highlighted the large extent of gene and pseudogene duplications in a conifer genome, in particular for genes of secondary (i.e. specialized) metabolism, and the potential for gain and loss of function for defense and adaptation. PMID:26017574

  9. PATTERNS OF NITROGEN AND CARBON STABLE ISOTOPE RATIOS IN MACROFUNGI, PLANTS AND SOILS IN TWO OLD-GROWTH CONIFER FORESTS

    EPA Science Inventory

    Natural abundance stable isotope ratios represent a potentially valuable tool for studying fungal ecology. We measured 15N and 13C in ectomycorrhizal and saprotrophic macrofungi from two old-growth conifer forests, and in plants, woody debris, and soils. Fungi, plants, and so...

  10. [Error structure and additivity of individual tree biomass model for four natural conifer species in Northeast China].

    PubMed

    Dogn, Li-hu; Li, Feng-ri; Song, Yu-wen

    2015-03-01

    Based on the biomass data of 276 sampling trees of Pinus koraiensis, Abies nephrolepis, Picea koraiensis and Larix gmelinii, the mono-element and dual-element additive system of biomass equations for the four conifer species was developed. The model error structure (additive vs. multiplicative) of the allometric equation was evaluated using the likelihood analysis, while nonlinear seemly unrelated regression was used to estimate the parameters in the additive system of biomass equations. The results indicated that the assumption of multiplicative error structure was strongly supported for the biomass equations of total and tree components for the four conifer species. Thus, the additive system of log-transformed biomass equations was developed. The adjusted coefficient of determination (Ra 2) of the additive system of biomass equations for the four conifer species was 0.85-0.99, the mean relative error was between -7.7% and 5.5%, and the mean absolute relative error was less than 30.5%. Adding total tree height in the additive systems of biomass equations could significantly improve model fitting performance and predicting precision, and the biomass equations of total, aboveground and stem were better than biomass equations of root, branch, foliage and crown. The precision of each biomass equation in the additive system varied from 77.0% to 99.7% with a mean value of 92.3% that would be suitable for predicting the biomass of the four natural conifer species.

  11. Improved white spruce (Picea glauca) genome assemblies and annotation of large gene families of conifer terpenoid and phenolic defense metabolism.

    PubMed

    Warren, René L; Keeling, Christopher I; Yuen, Macaire Man Saint; Raymond, Anthony; Taylor, Greg A; Vandervalk, Benjamin P; Mohamadi, Hamid; Paulino, Daniel; Chiu, Readman; Jackman, Shaun D; Robertson, Gordon; Yang, Chen; Boyle, Brian; Hoffmann, Margarete; Weigel, Detlef; Nelson, David R; Ritland, Carol; Isabel, Nathalie; Jaquish, Barry; Yanchuk, Alvin; Bousquet, Jean; Jones, Steven J M; MacKay, John; Birol, Inanc; Bohlmann, Joerg

    2015-07-01

    White spruce (Picea glauca), a gymnosperm tree, has been established as one of the models for conifer genomics. We describe the draft genome assemblies of two white spruce genotypes, PG29 and WS77111, innovative tools for the assembly of very large genomes, and the conifer genomics resources developed in this process. The two white spruce genotypes originate from distant geographic regions of western (PG29) and eastern (WS77111) North America, and represent elite trees in two Canadian tree-breeding programs. We present an update (V3 and V4) for a previously reported PG29 V2 draft genome assembly and introduce a second white spruce genome assembly for genotype WS77111. Assemblies of the PG29 and WS77111 genomes confirm the reconstructed white spruce genome size in the 20 Gbp range, and show broad synteny. Using the PG29 V3 assembly and additional white spruce genomics and transcriptomics resources, we performed MAKER-P annotation and meticulous expert annotation of very large gene families of conifer defense metabolism, the terpene synthases and cytochrome P450s. We also comprehensively annotated the white spruce mevalonate, methylerythritol phosphate and phenylpropanoid pathways. These analyses highlighted the large extent of gene and pseudogene duplications in a conifer genome, in particular for genes of secondary (i.e. specialized) metabolism, and the potential for gain and loss of function for defense and adaptation.

  12. Eriosomatine aphids (Hemiptera, Aphididae, Eriosomatinae) associated with moss and roots of conifer and willow in forests of the Pacific Northwest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apterous adult morphs of eriosomatine aphids (Hemiptera, Aphididae, Eriosomatinae) associated with moss and/or roots of conifer or willow in forests of the Pacific Northwest including Alaska are described, illustrated, and keyed. In total, seven species (Clydesmithia canadensis Danielsson, Melaphis ...

  13. Holocene vegetation and fire regimes in subalpine and mixed conifer forests, southern Rocky Mountains, USA

    USGS Publications Warehouse

    Anderson, R. Scott; Allen, C.D.; Toney, J.L.; Jass, R.B.; Bair, A.N.

    2008-01-01

    Our understanding of the present forest structure of western North America hinges on our ability to determine antecedent forest conditions. Sedimentary records from lakes and bogs in the southern Rocky Mountains of Colorado and New Mexico provide information on the relationships between climate and vegetation change, and fire history since deglaciation. We present a new pollen record from Hunters Lake (Colorado) as an example of a high-elevation vegetation history from the southern Rockies. We then present a series of six sedimentary records from ???2600 to 3500-m elevation, including sites presently at the alpine?subalpine boundary, within the Picea engelmannii?Abies lasiocarpa forest and within the mixed conifer forest, to determine the history of fire in high-elevation forests there. High Artemisia and low but increasing percentages of Picea and Pinus suggest vegetation prior to 13 500 calendar years before present (cal yr BP) was tundra or steppe, with open spruce woodland to ???11 900 cal yr BP. Subalpine forest (Picea engelmannii, Abies lasiocarpa) existed around the lake for the remainder of the Holocene. At lower elevations, Pinus ponderosa and/or contorta expanded 11 900 to 10 200 cal yr BP; mixed conifer forest expanded ???8600 to 4700 cal yr BP; and Pinus edulis expanded after ???4700 cal yr BP. Sediments from lake sites near the alpine?subalpine transition contained five times less charcoal than those entirely within subalpine forests, and 40 times less than bog sites within mixed conifer forest. Higher fire episode frequencies occurred between ???12 000 and 9000 cal yr BP (associated with the initiation or expansion of south-west monsoon and abundant lightning, and significant biomass during vegetation turnover) and at ???2000?1000 cal yr BP (related to periodic droughts during the long-term trend towards wetter conditions and greater biomass). Fire episode frequencies for subalpine?alpine transition and subalpine sites were on average 5 to 10 fire

  14. Passive Microwave Measurements Over Conifer Forests at L-Band and C-Band

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Lang, R.; Chauhan, N.; Kim, E.; Bidwell, S.; Goodberlet, M.; Haken, M.; deMatthaeis, P.

    2000-01-01

    Measurements have been made at L-band and C-band over conifer forests in Virginia to study the response of passive microwave instruments to biomass and soil moisture. A series of aircraft measurements were made in July, August and November, 1999 over relatively homogenous conifer forests of varying biomass. Three radiometers participated in these measurements. These were: 1) the L-band radiometer ESTAR, a horizontally polarized synthetic aperture radiometer which has been used extensively in past measurements of soil moisture; 2) the L-band radiometer SLFMR, a vertically polarized cross-track scanner which has been used successfully in the past for mapping sea surface salinity; and 3) The ACMR, a new C-band radiometer which operates at V- and H-polarization and in the configuration for these experiments did not scan. All three radiometers were flown on the NASA P-3 aircraft based at the Goddard Space Flight Center's Wallops Flight Facility. The ESTAR and SLFMR were mounted in the bomb bay of the P-3 and imaged across track whereas the ACMR was mounted to look aft at 54 degrees up from nadir. Data was collected at altitudes of 915 meters and 457 meters. The forests consisted of relatively homogeneous "managed" stands of conifer located near Waverly, Virginia. This is a relatively flat area about 30 miles southeast of Richmond, VA with numerous stands of trees being grown for the forestry industry. The stands selected for study consisted of areas of regrowth and mature stands of pine. In addition, a small stand of very large trees was observed. Soil moisture sampling was done in each stand during the aircraft over flights. Data was collected on July 7, August 27, November 15 and November 30, 1999. Measurements were made with ESTAR on all days. The ACMR flew on the summer missions and the SLFMR was present only on the August 27 flight. Soil moisture varied from quite dry on July 7 to quite moist on November 30 (which was shortly after a period of rain). The microwave

  15. A low diversity, seasonal tropical landscape dominated by conifers and peltasperms: Early Permian Abo Formation, New Mexico

    USGS Publications Warehouse

    DiMichele, W.A.; Chaney, D.S.; Nelson, W.J.; Lucas, S.G.; Looy, C.V.; Quick, K.; Jun, W.

    2007-01-01

    Walchian conifers (Walchia piniformis Sternberg, 1825) and peltasperms similar to Supaia thinnfeldioides White and cf. Supaia anomala White dominate floodplain deposits of a narrow stratigraphic interval of the middle Abo Formation, Lower Permian of central New Mexico. The plant fossils occur in thinly bedded units up to two meters thick, consisting of coarse siltstone to very fine sandstone with clay partings. Bedding is primarily tabular, thin, and bears rare ripple marks and trough cross beds. Bedding surfaces display mud cracks, raindrop imprints, horizontal and vertical burrows of invertebrates, and footprints of terrestrial vertebrates. These features indicate intermittent and generally unchannelized stream flow, with repeated exposure to air. Channels appear to have cannibalized one another on a slowly subsiding coastal plain. Conifers are dominant at three collecting sites and at three others Supaia dominates. Although each of these genera occurs in assemblages dominated by the other, there are no truly co-dominant assemblages. This pattern suggests alternative explanations. Landscapes could have consisted of a small-scale vegetational patchwork dominated almost monospecifically in any one patch, meaning that these plants could have coexisted across the landscape. On the other hand, conifer and supaioid dominance could have been temporally distinct, occurring during different episodes of sedimentation; although in the field there are no noticeable sedimentological differences between conifer-dominated and Supaia-dominated channel deposits, they may represent slightly different climatic regimes. The considerable morphological differences between conifers and Supaia suggest that the floristic patterns are not a taphonomic effect of the loss of a significant part of the original biodiversity. In general, the climate under which this vegetation developed appears to have been relatively warm and arid, based on the geology (pervasive red color [oxidation

  16. Chemosystematics and diagenesis of terpenoids in fossil conifer species and sediment from the Eocene Zeitz formation, Saxony, Germany

    NASA Astrophysics Data System (ADS)

    Otto, Angelika; Simoneit, Bernd R. T.

    2001-10-01

    The biomarker contents of three fossil conifer species ( Athrotaxis couttsiae, Taxodium balticum, Pinus palaeostrobus) and the clay sediment from the Eocene Zeitz formation, Germany, have been analyzed by gas chromatography-mass spectrometry. Triterpenoids of the oleanane, ursane and lupane series and aliphatic wax lipids are the major compounds in the total extracts of the sediment indicating a major angiosperm input. In contrast, diterpenoids (abietanes, phenolic abietanes, pimaranes, isopimaranes, kauranes, phyllocladanes, totaranes) and lignin degradation products are predominant in the conifer fossil extracts. Polar diterpenoids (ferruginol and derivatives, dehydroabietic acid) are preserved as major compounds in the conifers, accompained by saturated and aromatic diterpenoid products. The extracts of the fossil conifer species show characteristic biomarker patterns and contain terpenoids of chemosystematic value. The terpenoid composition of the fossil conifers is similar to that of related modern species. Phenolic abietanes (ferruginol, 6,7-dehydroferruginol, hydroxyferruginols, sugiol) which are known from modern species of the Cupressaceae and Podocarpaceae are the major terpenoids in shoots of Athrotaxis couttsiae and a cone of Taxodium balticum (both Cupressaceae). Sesquiterpenoids characteristic for Cupressaceae (cuparene, α-cedrene) are also present in Athrotaxis. Abietane-type acids (dehydroabietic acid, abietic acid) and saturated abietanes [fichtelite, 13α(H)-fichtelite] predominate in the extracts of a Pinus palaeostrobus cone and phenolic abietanes are not detectable. A diagenetic pathway for the degradation of abietic acid is proposed based on the presence of abietane-type acids and a series of their presumed degradation products in the Pinus cone. The formation of diagenetic products from the phenolic abietanes is also discussed.

  17. The conifer biomarkers dehydroabietic and abietic acids are widespread in Cyanobacteria

    NASA Astrophysics Data System (ADS)

    Costa, Maria Sofia; Rego, Adriana; Ramos, Vitor; Afonso, Tiago B.; Freitas, Sara; Preto, Marco; Lopes, Viviana; Vasconcelos, Vitor; Magalhães, Catarina; Leão, Pedro N.

    2016-03-01

    Terpenes, a large family of natural products with important applications, are commonly associated with plants and fungi. The diterpenoids dehydroabietic and abietic acids are defense metabolites abundant in resin, and are used as biomarkers for conifer plants. We report here for the first time that the two diterpenoid acids are produced by members of several genera of cyanobacteria. Dehydroabietic acid was isolated from two cyanobacterial strains and its identity was confirmed spectroscopically. One or both of the diterpenoids were detected in the cells of phylogenetically diverse cyanobacteria belonging to four cyanobacterial ‘botanical orders’, from marine, estuarine and inland environments. Dehydroabietic acid was additionally found in culture supernatants. We investigated the natural role of the two resin acids in cyanobacteria using ecologically-relevant bioassays and found that the compounds inhibited the growth of a small coccoid cyanobacterium. The unexpected discovery of dehydroabietic and abietic acids in a wide range of cyanobacteria has implications for their use as plant biomarkers.

  18. Characterization of polymorphic microsatellite markers in Pinus armandii (Pinaceae), an endemic conifer species to China1

    PubMed Central

    Dong, Wan-Lin; Wang, Ruo-Nan; Yan, Xiao-Hao; Niu, Chuan; Gong, Lin-Lin; Li, Zhong-Hu

    2016-01-01

    Premise of the study: Pinus armandii (Pinaceae) is an important conifer tree species in central and southwestern China, and it plays a key role in the local forest ecosystems. To investigate its population genetics and design effective conservation strategies, we characterized 18 polymorphic microsatellite markers for this species. Methods and Results: Eighteen novel polymorphic and 16 monomorphic microsatellite loci of P. armandii were isolated using Illumina MiSeq technology. The number of alleles per locus ranged from two to five. The expected heterozygosity ranged from 0.061 to 0.609 with an average of 0.384, and the observed heterozygosity ranged from 0.063 to 0.947 with an average of 0.436. Seventeen loci could be successfully transferred to five related Pinus species (P. koraiensis, P. griffithii, P. sibirica, P. pumila, and P. bungeana). Conclusions: These novel microsatellites could potentially be used to investigate the population genetics of P. armandii and related species. PMID:27785387

  19. Highly Laminated Soft Magnetic Electroplated CoNiFe Thick Films

    SciTech Connect

    Kim, J; Kim, M; Herrault, F; Park, J; Allen, MG

    2013-01-01

    The fabrication and characterization of highly laminated (similar to 40 layers), thick (similar to 40 mu m) films of magnetically soft cobalt-nickel-iron are presented. Thick film fabrication is based on automated sequential electrodeposition of alternating CoNiFe and copper layers, followed by selective copper removal. The film, comprised tens of 1 mu m thick laminations, exhibits saturation flux density of 1.8 T and coercivity of approximately 1.3 Oe. High-frequency film characterization took place in a 36-turn test inductor, which demonstrated constant inductance of 1.6 mu H up to 10 MHz, indicating suppressed eddy-current loss. Quality factor exceeding 40 at 1 MHz, surpassing the performance of similarly fabricated Permalloy (Ni80Fe20) films.

  20. The conifer biomarkers dehydroabietic and abietic acids are widespread in Cyanobacteria

    PubMed Central

    Costa, Maria Sofia; Rego, Adriana; Ramos, Vitor; Afonso, Tiago B.; Freitas, Sara; Preto, Marco; Lopes, Viviana; Vasconcelos, Vitor; Magalhães, Catarina; Leão, Pedro N.

    2016-01-01

    Terpenes, a large family of natural products with important applications, are commonly associated with plants and fungi. The diterpenoids dehydroabietic and abietic acids are defense metabolites abundant in resin, and are used as biomarkers for conifer plants. We report here for the first time that the two diterpenoid acids are produced by members of several genera of cyanobacteria. Dehydroabietic acid was isolated from two cyanobacterial strains and its identity was confirmed spectroscopically. One or both of the diterpenoids were detected in the cells of phylogenetically diverse cyanobacteria belonging to four cyanobacterial ‘botanical orders’, from marine, estuarine and inland environments. Dehydroabietic acid was additionally found in culture supernatants. We investigated the natural role of the two resin acids in cyanobacteria using ecologically-relevant bioassays and found that the compounds inhibited the growth of a small coccoid cyanobacterium. The unexpected discovery of dehydroabietic and abietic acids in a wide range of cyanobacteria has implications for their use as plant biomarkers. PMID:26996104

  1. Lichen communities on conifers in Southern California mountains: an ecological survey relative to oxidant air pollution

    SciTech Connect

    Sigal, L.L.; Nash T.H. III

    1983-01-01

    In comparison with collections from the early 1900's when oxidant air pollution was essentially absent, 50% fewer lichen species were found on conifers during 3 yr (1976-1979) of collecting and sampling in the mountains of Southern California. Among the five mountain ranges studied, the San Bernardino Mountains, the region with the highest oxidant levels, had lower lichen frequency and cover values. Within the San Bernardino study sites, lichen cover was inversely related to estimated oxidant doses. Furthermore, at sites with high oxidant levels, marked morphological deterioration of the common species Hypogymnia enteromorpha was documented. Transplants of this species from the relatively unpolluted Cuyamaca Rancho State Park in the San Bernardino Mountains exhibited similar deterioration after a year's exposure.

  2. Lichen communities on conifers in Southern California mountains: an ecological survey relative to oxidant air pollution

    SciTech Connect

    Sigal, L.L.; Nash, T.H. III

    1983-01-01

    In comparison with collections from the early 1900's when oxidant air pollution was essentially absent, 50% fewer lichen species were found on conifers during 3 yr (1976-1979) of collecting and sampling in the mountains of Southern California. Among the five mountain ranges studied, the San Bernardino Mountains, the region with the highest oxidant levels, had lower lichen frequency and cover values. Within the San Bernardino study sites, lichen cover was inversely related to estimated oxidant doses. Furthermore, at sites with high oxidant levels, marked morphological deterioration of the common species Hypogymnia enteromorpha was documented. Transplants of this species from the relatively unpolluted Cuyamaca Rancho State Park into the San Bernardino Mountains exhibited similar deterioration after a year's exposure. 4 figures, 9 tables.

  3. The conifer biomarkers dehydroabietic and abietic acids are widespread in Cyanobacteria.

    PubMed

    Costa, Maria Sofia; Rego, Adriana; Ramos, Vitor; Afonso, Tiago B; Freitas, Sara; Preto, Marco; Lopes, Viviana; Vasconcelos, Vitor; Magalhães, Catarina; Leão, Pedro N

    2016-01-01

    Terpenes, a large family of natural products with important applications, are commonly associated with plants and fungi. The diterpenoids dehydroabietic and abietic acids are defense metabolites abundant in resin, and are used as biomarkers for conifer plants. We report here for the first time that the two diterpenoid acids are produced by members of several genera of cyanobacteria. Dehydroabietic acid was isolated from two cyanobacterial strains and its identity was confirmed spectroscopically. One or both of the diterpenoids were detected in the cells of phylogenetically diverse cyanobacteria belonging to four cyanobacterial 'botanical orders', from marine, estuarine and inland environments. Dehydroabietic acid was additionally found in culture supernatants. We investigated the natural role of the two resin acids in cyanobacteria using ecologically-relevant bioassays and found that the compounds inhibited the growth of a small coccoid cyanobacterium. The unexpected discovery of dehydroabietic and abietic acids in a wide range of cyanobacteria has implications for their use as plant biomarkers. PMID:26996104

  4. Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA

    PubMed Central

    Heady, Paul A.; Hayes, John P.; Frick, Winifred F.

    2013-01-01

    Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (<1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscape-scale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roosts. PMID:23483936

  5. Seasonal photosynthetic activity in evergreen conifer leaves monitored with spectral reflectance

    NASA Astrophysics Data System (ADS)

    Wong, C. Y.; Gamon, J. A.

    2013-12-01

    Boreal evergreen conifers must maintain photosynthetic systems in environments where temperatures vary greatly across seasons from high temperatures in the summer to freezing levels in the winter. This involves seasonal downregulation and photoprotection during periods of extreme temperatures. To better understand this downregulation, seasonal dynamics of photosynthesis of lodgepole (Pinus contorta D.) and ponderosa pine (Pinus ponderosa D.) were monitored in Edmonton, Canada over two years. Spectral reflectance at the leaf and stand scales was measured weekly and the Photochemical Reflectance Index (PRI), often used as a proxy for chlorophyll and carotenoid pigment levels and photosynthetic light-use efficiency (LUE), was used to track the seasonal dynamics of photosynthetic activity. Additional physiological measurements included leaf pigment content, chlorophyll fluorescence, and gas exchange. All the metrics indicate large seasonal changes in photosynthetic activity, with a sharp transition from winter downregulation to active photosynthesis in the spring and a more gradual fall transition into winter. The PRI was a good indicator of several other variables including seasonally changing photosynthetic activity, chlorophyll fluorescence, photosynthetic LUE, and pigment pool sizes. Over the two-year cycle, PRI was primarily driven by changes in constitutive (chlorophyll:carotenoid) pigment levels correlated with seasonal photosynthetic activity, with a much smaller variation caused by diurnal changes in xanthophyll cycle activity (conversion between violaxanthin & zeaxanthin). Leaf and canopy scale PRI measurements exhibited parallel responses during the winter-spring transition. Together, our findings indicate that evergreen conifers photosynthetic system possesses a remarkable degree of resilience in response to large temperature changes across seasons, and that optical remote sensing can be used to observe the seasonal effects on photosynthesis and

  6. Climate Effects on Soil Carbon Sequestration in a Grass, Oak and Conifer Ecosystem of California

    NASA Astrophysics Data System (ADS)

    Pittiglio, S. L.; Zasoski, R.

    2007-12-01

    Dissolved organic matter (DOM) leaching from decomposing detritus accumulated above mineral soils is an important carbon (C) and nitrogen (N) flux that influences biogeochemical processes, C sequestration and the health of individual ecosystems. Previous studies have shown that the main process controlling DOM mobility in soils is sorption in the mineral horizons that adds to stabilized organic matter pools. The objective of this study was to determine the effect of temperature and incubation time on DOC and DON biodegradation and sorption in the mineral soil. Surface litter from a grass, oak and a conifer site were leached with deionized water for 5, 15 or 96 hours at 4, 20 or 30oC. The resulting DOM solutions were characterized using 13C NMR, XAD-8 resin and UV-vis spectroscopy. The biodegradable fraction (BDOC) of these solutions was quantified using inoculum from A horizon soils. The DOM solutions were also used in sorption experiments on A horizon soils. Supernatant from the A horizon sorption experiment was then used in a sorption experiment on Bt horizon soils and analyzed for BDOC using Bt horizon inoculum. The ability of the soils to adsorb DOC increased with increasing aromaticity in the DOC solution. Therefore, conifer DOM exhibited greater sorption than oak and grass DOM due to higher aromaticity. In all horizons, we observed net release of indigenous OM when OM-free solution was added. Net release of OM was greatest from the soils from the pine site, which had the greatest OM content among the soils we studied. ***Results still pending***

  7. Bat response to differing fire severity in mixed-conifer forest California, USA.

    PubMed

    Buchalski, Michael R; Fontaine, Joseph B; Heady, Paul A; Hayes, John P; Frick, Winifred F

    2013-01-01

    Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (<1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscape-scale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roosts.

  8. Cenozoic climate change shaped the evolutionary ecophysiology of the Cupressaceae conifers.

    PubMed

    Pittermann, Jarmila; Stuart, Stephanie A; Dawson, Todd E; Moreau, Astrid

    2012-06-12

    The Cupressaceae clade has the broadest diversity in habitat and morphology of any conifer family. This clade is characterized by highly divergent physiological strategies, with deciduous swamp-adapted genera-like Taxodium at one extreme, and evergreen desert genera-like Cupressus at the other. The size disparity within the Cupressaceae is equally impressive, with members ranging from 5-m-tall juniper shrubs to 100-m-tall redwood trees. Phylogenetic studies demonstrate that despite this variation, these taxa all share a single common ancestor; by extension, they also share a common ancestral habitat. Here, we use a common-garden approach to compare xylem and leaf-level physiology in this family. We then apply comparative phylogenetic methods to infer how Cenozoic climatic change shaped the morphological and physiological differences between modern-day members of the Cupressaceae. Our data show that drought-resistant crown clades (the Cupressoid and Callitroid clades) most likely evolved from drought-intolerant Mesozoic ancestors, and that this pattern is consistent with proposed shifts in post-Eocene paleoclimates. We also provide evidence that within the Cupressaceae, the evolution of drought-resistant xylem is coupled to increased carbon investment in xylem tissue, reduced xylem transport efficiency, and at the leaf level, reduced photosynthetic capacity. Phylogenetically based analyses suggest that the ancestors of the Cupressaceae were dependent upon moist habitats, and that drought-resistant physiology developed along with increasing habitat aridity from the Oligocene onward. We conclude that the modern biogeography of the Cupressaceae conifers was shaped in large part by their capacity to adapt to drought.

  9. Cenozoic climate change shaped the evolutionary ecophysiology of the Cupressaceae conifers

    PubMed Central

    Pittermann, Jarmila; Stuart, Stephanie A.; Dawson, Todd E.; Moreau, Astrid

    2012-01-01

    The Cupressaceae clade has the broadest diversity in habitat and morphology of any conifer family. This clade is characterized by highly divergent physiological strategies, with deciduous swamp-adapted genera-like Taxodium at one extreme, and evergreen desert genera-like Cupressus at the other. The size disparity within the Cupressaceae is equally impressive, with members ranging from 5-m-tall juniper shrubs to 100-m-tall redwood trees. Phylogenetic studies demonstrate that despite this variation, these taxa all share a single common ancestor; by extension, they also share a common ancestral habitat. Here, we use a common-garden approach to compare xylem and leaf-level physiology in this family. We then apply comparative phylogenetic methods to infer how Cenozoic climatic change shaped the morphological and physiological differences between modern-day members of the Cupressaceae. Our data show that drought-resistant crown clades (the Cupressoid and Callitroid clades) most likely evolved from drought-intolerant Mesozoic ancestors, and that this pattern is consistent with proposed shifts in post-Eocene paleoclimates. We also provide evidence that within the Cupressaceae, the evolution of drought-resistant xylem is coupled to increased carbon investment in xylem tissue, reduced xylem transport efficiency, and at the leaf level, reduced photosynthetic capacity. Phylogenetically based analyses suggest that the ancestors of the Cupressaceae were dependent upon moist habitats, and that drought-resistant physiology developed along with increasing habitat aridity from the Oligocene onward. We conclude that the modern biogeography of the Cupressaceae conifers was shaped in large part by their capacity to adapt to drought. PMID:22628565

  10. Toward meaningful snag-management guidelines for postfire salvage logging in North American conifer forests.

    PubMed

    Hutto, Richard L

    2006-08-01

    The bird species in western North America that are most restricted to, and therefore most dependent on, severely burned conifer forests during the first years following afire event depend heavily on the abundant standing snags for perch sites, nest sites, and food resources. Thus, it is critical to develop and apply appropriate snag-management guidelines to implement postfire timber harvest operations in the same locations. Unfortunately, existing guidelines designed for green-tree forests cannot be applied to postfire salvage sales because the snag needs of snag-dependent species in burned forests are not at all similar to the snag needs of snag-dependent species in green-tree forests. Birds in burned forests have very different snag-retention needs from those cavity-nesting bird species that have served as the focus for the development of existing snag-management guidelines. Specifically, many postfire specialists use standing dead trees not only for nesting purposes but for feeding purposes as well. Woodpeckers, in particular specialize on wood-boring beetle larvae that are superabundant in fire-killed trees for several years following severe fire. Species such as the Black-backed Woodpecker (Picoides arcticus) are nearly restricted in their habitat distribution to severely burned forests. Moreover existing postfire salvage-logging studies reveal that most postfire specialist species are completely absent from burned forests that have been (even partially) salvage logged. I call for the long-overdue development and use of more meaningful snag-retention guidelines for postfire specialists, and I note that the biology of the most fire-dependent bird species suggests that even a cursory attempt to meet their snag needs would preclude postfire salvage logging in those severely burned conifer forests wherein the maintenance of biological diversity is deemed important.

  11. De Novo Transcriptome Assembly and Characterization for the Widespread and Stress-Tolerant Conifer Platycladus orientalis.

    PubMed

    Hu, Xian-Ge; Liu, Hui; Jin, YuQing; Sun, Yan-Qiang; Li, Yue; Zhao, Wei; El-Kassaby, Yousry A; Wang, Xiao-Ru; Mao, Jian-Feng

    2016-01-01

    Platycladus orientalis, of the family Cupressaceae, is a widespread conifer throughout China and is extensively used for ecological reforestation, horticulture, and in medicine. Transcriptome assemblies are required for this ecologically important conifer for understanding genes underpinning adaptation and complex traits for breeding programs. To enrich the species' genomic resources, a de novo transcriptome sequencing was performed using Illumina paired-end sequencing. In total, 104,073,506 high quality sequence reads (approximately 10.3 Gbp) were obtained, which were assembled into 228,948 transcripts and 148,867 unigenes that were longer than 200 nt. Quality assessment using CEGMA showed that the transcriptomes obtained were mostly complete for highly conserved core eukaryotic genes. Based on similarity searches with known proteins, 62,938 (42.28% of all unigenes), 42,158 (28.32%), and 23,179 (15.57%) had homologs in the Nr, GO, and KOG databases, 25,625 (17.21%) unigenes were mapped to 322 pathways by BLASTX comparison against the KEGG database and 1,941 unigenes involved in environmental signaling and stress response were identified. We also identified 43 putative terpene synthase (TPS) functional genes loci and compared them with TPSs from other species. Additionally, 5,296 simple sequence repeats (SSRs) were identified in 4,715 unigenes, which were assigned to 142 motif types. This is the first report of a complete transcriptome analysis of P. orientalis. These resources provide a foundation for further studies of adaptation mechanisms and molecular-based breeding programs. PMID:26881995

  12. De Novo Transcriptome Assembly and Characterization for the Widespread and Stress-Tolerant Conifer Platycladus orientalis

    PubMed Central

    Jin, YuQing; Sun, Yan-Qiang; Li, Yue; Zhao, Wei; El-Kassaby, Yousry A.; Wang, Xiao-Ru; Mao, Jian-Feng

    2016-01-01

    Platycladus orientalis, of the family Cupressaceae, is a widespread conifer throughout China and is extensively used for ecological reforestation, horticulture, and in medicine. Transcriptome assemblies are required for this ecologically important conifer for understanding genes underpinning adaptation and complex traits for breeding programs. To enrich the species’ genomic resources, a de novo transcriptome sequencing was performed using Illumina paired-end sequencing. In total, 104,073,506 high quality sequence reads (approximately 10.3 Gbp) were obtained, which were assembled into 228,948 transcripts and 148,867 unigenes that were longer than 200 nt. Quality assessment using CEGMA showed that the transcriptomes obtained were mostly complete for highly conserved core eukaryotic genes. Based on similarity searches with known proteins, 62,938 (42.28% of all unigenes), 42,158 (28.32%), and 23,179 (15.57%) had homologs in the Nr, GO, and KOG databases, 25,625 (17.21%) unigenes were mapped to 322 pathways by BLASTX comparison against the KEGG database and 1,941 unigenes involved in environmental signaling and stress response were identified. We also identified 43 putative terpene synthase (TPS) functional genes loci and compared them with TPSs from other species. Additionally, 5,296 simple sequence repeats (SSRs) were identified in 4,715 unigenes, which were assigned to 142 motif types. This is the first report of a complete transcriptome analysis of P. orientalis. These resources provide a foundation for further studies of adaptation mechanisms and molecular-based breeding programs. PMID:26881995

  13. Impact of Conifer Forest Litter on Microwave Emission at L-Band

    NASA Technical Reports Server (NTRS)

    Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.; Cosh, Michael H.; Joseph, Alicia T.; Jackson, Thomas J.

    2011-01-01

    This study reports on the utilization of microwave modeling, together with ground truth, and L-band (1.4-GHz) brightness temperatures to investigate the passive microwave characteristics of a conifer forest floor. The microwave data were acquired over a natural Virginia Pine forest in Maryland by a ground-based microwave active/passive instrument system in 2008/2009. Ground measurements of the tree biophysical parameters and forest floor characteristics were obtained during the field campaign. The test site consisted of medium-sized evergreen conifers with an average height of 12 m and average diameters at breast height of 12.6 cm. The site is a typical pine forest site in that there is a surface layer of loose debris/needles and an organic transition layer above the mineral soil. In an effort to characterize and model the impact of the surface litter layer, an experiment was conducted on a day with wet soil conditions, which involved removal of the surface litter layer from one half of the test site while keeping the other half undisturbed. The observations showed detectable decrease in emissivity for both polarizations after the surface litter layer was removed. A first-order radiative transfer model of the forest stands including the multilayer nature of the forest floor in conjunction with the ground truth data are used to compute forest emission. The model calculations reproduced the major features of the experimental data over the entire duration, which included the effects of surface litter and ground moisture content on overall emission. Both theory and experimental results confirm that the litter layer increases the observed canopy brightness temperature and obscure the soil emission.

  14. Black-backed woodpecker habitat suitability mapping using conifer snag basal area estimated from airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Casas Planes, Á.; Garcia, M.; Siegel, R.; Koltunov, A.; Ramirez, C.; Ustin, S.

    2015-12-01

    Occupancy and habitat suitability models for snag-dependent wildlife species are commonly defined as a function of snag basal area. Although critical for predicting or assessing habitat suitability, spatially distributed estimates of snag basal area are not generally available across landscapes at spatial scales relevant for conservation planning. This study evaluates the use of airborne laser scanning (ALS) to 1) identify individual conifer snags and map their basal area across a recently burned forest, and 2) map habitat suitability for a wildlife species known to be dependent on snag basal area, specifically the black-backed woodpecker (Picoides arcticus). This study focuses on the Rim Fire, a megafire that took place in 2013 in the Sierra Nevada Mountains of California, creating large patches of medium- and high-severity burned forest. We use forest inventory plots, single-tree ALS-derived metrics and Gaussian processes classification and regression to identify conifer snags and estimate their stem diameter and basal area. Then, we use the results to map habitat suitability for the black-backed woodpecker using thresholds for conifer basal area from a previously published habitat suitability model. Local maxima detection and watershed segmentation algorithms resulted in 75% detection of trees with stem diameter larger than 30 cm. Snags are identified with an overall accuracy of 91.8 % and conifer snags are identified with an overall accuracy of 84.8 %. Finally, Gaussian process regression reliably estimated stem diameter (R2 = 0.8) using height and crown area. This work provides a fast and efficient methodology to characterize the extent of a burned forest at the tree level and a critical tool for early wildlife assessment in post-fire forest management and biodiversity conservation.

  15. The gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer-feeding beetles.

    PubMed

    Berasategui, Aileen; Axelsson, Karolin; Nordlander, Göran; Schmidt, Axel; Borg-Karlson, Anna-Karin; Gershenzon, Jonathan; Terenius, Olle; Kaltenpoth, Martin

    2016-08-01

    The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta-analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on nonconifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis-associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or through the supplementation of essential nutrients. PMID:27199034

  16. Height-diameter relationships for conifer species on the Blacks Mountain Experimental Forest. Forest Service research note (Final)

    SciTech Connect

    Dolph, K.L.; Mori, S.R.; Oliver, W.W.

    1995-03-01

    An equation is presented for predicting total height as a function of diameter outside bark at breast height for conifer species of the eastside pine type on the Blacks Mountain Experimental Forest in northeastern California. Weighted nonlinear regression was used to estimate the equation coefficients. The equation, along with the species-specific regression coefficients, provides a reliable basis for estimating missing heights on inventory and growth plots.

  17. Local adaptation to temperature and precipitation in naturally fragmented populations of Cephalotaxus oliveri, an endangered conifer endemic to China

    PubMed Central

    Wang, Ting; Wang, Zhen; Xia, Fan; Su, Yingjuan

    2016-01-01

    Cephalotaxus oliveri is an endangered tertiary relict conifer endemic to China. The species survives in a wide range from west to east with heterogeneous climatic conditions. Precipitation and temperature are main restrictive factors for distribution of C. oliveri. In order to comprehend the mechanism of adaptive evolution to climate variation, we employed ISSR markers to detect adaptive evolution loci, to identify the association between variation in temperature and precipitation and adaptive loci, and to investigate the genetic structure for 22 C. oliveri natural populations. In total, 14 outlier loci were identified, of which five were associated with temperature and precipitation. Among outlier loci, linkage disequilibrium (LD) was high (42.86%), which also provided strong evidence for selection. In addition, C. oliveri possessed high genetic variation (93.31%) and population differentiation, which may provide raw material to evolution and accelerate local adaptation, respectively. Ecological niche modeling showed that global warming will cause a shift for populations of C. oliveri from south to north with a shrinkage of southern areas. Our results contribute to understand the potential response of conifers to climatic changes, and provide new insights for conifer resource management and conservation strategies. PMID:27113970

  18. Influence of Snow Cover Duration on Soil Evaporation and Respiration Efflux in Mixed-conifer Ecosystems

    NASA Astrophysics Data System (ADS)

    Nelson, K.; Papuga, S. A.; John, G. P.; Minor, R.; Barron-Gafford, G. A.

    2011-12-01

    Subalpine mixed-conifer ecosystems are sensitive to a warming climate and are dependent on snowfall, which is expected to decrease under projected climate change. These changes in snowpack are likely to have important consequences for water and carbon cycling in these ecosystems and those downstream in the watersheds. Particularly within the semiarid southwest, such transitions to a drier and warmer environment will directly influence localized water and carbon dynamics and indirectly influence regional-scale levels of water availability and carbon sequestration. Therefore, in this study we monitored soil evaporation and respiration to evaluate how snow accumulation and duration of snow cover affected these effluxes. Our study took place within a mixed-conifer ecosystem within the Santa Catalina Mountains about 10 km north of Tucson, Arizona. Here, three understory time-lapse digital cameras have monitored snow cover within the footprint of an eddy covariance tower for nearly two years. Using these cameras, we identified locations with short and long snow duration. We then placed 6 soil collars (3 in short snow duration; 3 in long snow duration) within the field of view of each camera. Since July 2010, evaporation and soil respiration data have been collected regularly from these collars; soil temperature and soil moisture measurements were also collected. Our primary findings include: (1) evaporation fluxes do not vary drastically between long and short snow season sites, (2) evaporation fluxes for both short and long snow seasons have a strong relationship with soil moisture and a poor relationship with soil temperature, (3) CO2 fluxes vary noticeably between long and short snow season sites throughout the year, with short snow season fluxes typically higher than those of long snow season sites, and (4) CO2 fluxes for short and long snow seasons have a strong relationship with soil temperature and a poor relationship with soil moisture. Our findings suggest that

  19. Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter

    USGS Publications Warehouse

    Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

    2012-01-01

    High tissue nitrogen (N) accelerates decomposition of high-quality leaf litter in the early phases of mass loss, but the influence of initial tissue N variation on the decomposition of lignin-rich litter is less resolved. Because environmental changes such as atmospheric N deposition and elevated CO2 can alter tissue N levels within species more rapidly than they alter the species composition of ecosystems, it is important to consider how within-species variation in tissue N may shape litter decomposition and associated N dynamics. Douglas-fir (Pseudotsuga menziesii ) is a widespread lignin-rich conifer that dominates forests of high carbon (C) storage across western North America, and displays wide variation in tissue and litter N that reflects landscape variation in soil N. We collected eight unique Douglas-fir litter sources that spanned a two-fold range in initial N concentrations (0.67–1.31%) with a narrow range of lignin (29–35%), and examined relationships between initial litter chemistry, decomposition, and N dynamics in both ambient and N fertilized plots at four sites over 3 yr. High initial litter N slowed decomposition rates in both early (0.67 yr) and late (3 yr) stages in unfertilized plots. Applications of N fertilizer to litters accelerated early-stage decomposition, but slowed late-stage decomposition, and most strongly affected low-N litters, which equalized decomposition rates across litters regardless of initial N concentrations. Decomposition of N-fertilized litters correlated positively with initial litter manganese (Mn) concentrations, with litter Mn variation reflecting faster turnover of canopy foliage in high N sites, producing younger litterfall with high N and low Mn. Although both internal and external N inhibited decomposition at 3 yr, most litters exhibited net N immobilization, with strongest immobilization in low-N litter and in N-fertilized plots. Our observation for lignin-rich litter that high initial N can slow decomposition

  20. Effects of fire and harvest on soil respiration in a mixed-conifer forest

    NASA Astrophysics Data System (ADS)

    Dore, S.; Fry, D.; Stephens, S.

    2012-12-01

    Forest ecosystems, and in particular forest soils, constitute a major reservoir of global terrestrial carbon and soil respiration is the largest carbon loss from these ecosystems. Disturbances can affect soil respiration, causing physical and chemical changes in soil characteristics, adding both, above and belowground necromass, and changing microclimatic conditions. This could signify an important and long term carbon loss, even higher than the carbon directly removed by the harvest or during fire. These losses need to be included when quantifying the net carbon balance of forests. We measured the impacts of prescribed fire and clear-cut tree harvest on soil respiration in a mixed-conifer forest in the central Sierra Nevada. The prescribed fire treatment was implemented in 2002 and again in 2009. Four areas were clear-cut harvested in 2010. In half of these units the soils were mechanically ripped to reduce soil compaction, a common practice in the Sierra Nevada industrial forest lands. Soil respiration was measured using two different techniques: the chamber method and the gradient method. Soil respiration was affected by treatments in two different ways. First, treatments changed soil temperature and soil water content, the main abiotic factors controlling soil respiration. The clear cut and the prescribed fire treatments created higher maximum soil temperature and more available soil water content, environmental conditions favorable to soil respiration. However, the loss of trees and thus fine roots, and the decrease of soil litter and organic layers, because of their combustion or removal, had a negative effect on soil respiration that was stronger than the positive effect due to more favorable post disturbance environmental conditions. Soil respiration rates remained steady 1-2 years after treatments and no increase or spikes of soil respiration were measured after treatments. Continuous measurements of CO2 concentrations at different soil depths improved our

  1. Hydraulic compensation in northern Rocky Mountain conifers: does successional position and life history matter?

    PubMed

    Sala, Anna

    2006-08-01

    As trees grow tall and the resistance of the hydraulic pathway increases, water supply to foliage may decrease forcing stomata to close and CO2 uptake to decline. Several structural (e.g. biomass allocation) and physiological adjustments, however, may partially or fully compensate for such hydraulic constraints and prevent limitations on CO2 uptake and growth. The degree to which trees compensate for hydraulic constraints as they grow tall may depend on the costs and benefits associated with hydraulic compensation according to their ecology and life history. Because later successional Rocky Mountain conifers are more shade tolerant, optimization of CO2 uptake as trees grow tall and shade increases may confer greater benefits than in earlier successional species. If so, higher compensation for hydraulic constraints is expected in later successional species relative to co-occurring earlier successional species. I have examined height-related changes of crown stomatal conductance on a leaf area basis (G(LA)) and leaf to sapwood ratios (A(L):A(S)) for five conifer species in the northern Rocky Mountains. Species were arranged in pairs, each pair consisting of an early and late successional species. For high elevations I used, respectively, whitebark pine (Pinus albicaulis) and subalpine fir (Abies lasiocarpa); for mid-elevations, western larch (Larix occidentalis) and Douglas-fir (Pseudotsuga menziesii); for lower elevations, ponderosa pine (Pinus ponderosa) and Douglas-fir. A(L):A(S) either decreased (subalpine fir, ponderosa pine), remained constant (Douglas-fir, western larch) or increased (whitebark pine) with tree height. As hypothesized, earlier successional species (ponderosa pine, whitebark pine and western larch) exhibited significantly stronger decreases of G(LA) with tree height relative to their later successional pairs (Douglas-fir and subalpine fir), which fully compensated for height-related hydraulic constraints on G(LA). A life history approach that

  2. Quantifying cambial activity of high-elevation conifers in the Great Basin, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Ziaco, E.; Biondi, F.; Rossi, S.; Deslauriers, A.

    2013-12-01

    Understanding the physiological mechanisms that control the formation of tree rings provides the necessary biological basis for developing dendroclimatic reconstructions and dendroecological histories. Studies of wood formation in the Great Basin are now being conducted in connection with the Nevada Climate-ecohydrological Assessment Network (NevCAN), a recently established transect of valley-to-mountaintop instrumented stations in the Snake and Sheep Ranges of the Great Basin. Automated sensors record meteorological, soil, and vegetational variables at these sites, providing unique opportunities for ecosystem science, and are being used to investigate the ecological implications of xylogenesis. We present here an initial study based on microcores collected during summer 2013 from mountain and subalpine conifers (including Great Basin bristlecone pine, Pinus longaeva) growing on the west slope of Mt. Washington. Samples were taken from the mountain west (SM; 2810 m elevation) and the subalpine west (SS, 3355 m elevation) NevCAN sites on June 16th and 27th, 2013. The SS site was further subdivided in a high (SSH) and a low (SSL) group of trees, separated by about 10 m in elevation. Microscopic analyses showed the effect of elevation on cambial activity, as annual ring formation was more advanced at the lower (mountain) site compared to the higher (subalpine) one. At all sites cambium size showed little variations between the two sampling dates. The number of xylem cells in the radial enlargement phase decreased between the two sampling dates at the mountain site but increased at the subalpine site, confirming a delayed formation of wood at the higher elevations. Despite relatively high within-site variability, a general trend of increasing number of cells in the lignification phase was found at all sites. Mature cells were present only at the mountain site on June 27th. Spatial differences in the xylem formation process emerged at the species level and, within

  3. Scaling of phloem structure and optimality of sugar transport in conifer needles

    NASA Astrophysics Data System (ADS)

    Jensen, Kaare H.; Ronellenfitsch, Henrik; Liesche, Johannes; Holbrook, N. Michele; Schulz, Alexander; Katifori, Eleni

    2015-11-01

    The phloem vascular system facilitates transport of energy-rich sugar and signalling molecules in plants, thus permitting long-range communication within the organism and growth of non-photosynthesizing organs such as roots and fruits. The flow is driven by osmotic pressure, generated by differences in sugar concentration between distal parts of the plant. The phloem is an intricate distribution system, and many questions about its regulation and structural diversity remain unanswered. Here, we investigate the phloem structure in the simplest possible geometry: a linear leaf, found, for example, in the needles of conifer trees. We measure the phloem structure in four tree species representing a diverse set of habitats and needle sizes, from 1 cm (Picea omorika) to 35 cm (Pinus palustris). We show that the phloem shares common traits across these four species and find that the size of its conductive elements obeys a power law. We present a minimal model that accounts for these common traits and takes into account the transport strategy and natural constraints. This minimal model predicts a power law phloem distribution consistent with transport energy minimization, suggesting that energetics are more important than translocation speed at the leaf level.

  4. Determination of the molecular signature of fossil conifers by experimental palaeochemotaxonomy - Part 1: The Araucariaceae family

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Hautevelle, Y.; Michels, R.

    2013-03-01

    Twelve species of the conifer family Araucariaceae, including Araucaria (6 species), Agathis (3 species) and Wollemia (1 species) genera, were submitted to artificial maturation by confined pyrolysis. The aim of these experiments is to transform the biomolecules synthesized by these species into their homologous geomolecules in laboratory conditions. Determination of the diagenetic molecular signatures of Araucariaceae through experimentation on extant representatives allows us to complete our knowledge in botanical palaeochemotaxonomy. Such knowledge is relevant to palaeoenvironmental, environmental and archaeology purposes. All artificially diagenetic species of Araucariaceae are firstly characterized by a predominance of saturated tetracyclic diterpenoids including ent-beyerane, phyllocladanes and ent-kauranes. Moreover, Araucaria genus shows a high relative abundance of bicyclic sesquiterpenoids, particularly the cadalane-type compounds accompanied by those of eudesmane and bisabolane types as well as chamazulene and pentamethyl-dihydroindenes. Diterpenoids are of labdane, isopimarane and abietane types (essentially derived from abietanoic acids) as well as isohexyl alkylaromatic hydrocarbons. Compared to the tetracyclic diterpenoids, these compounds show a relatively lower abundance, reaching trace levels in the case of saturated abietanes. Distributions of sesquiterpenoids and diterpenoids of Agathis show some similarities to that of Araucaria, with the exception of one species, in which the tetracyclic compounds are absent and the abietane type (essentially derived from abietanoic acids) predominant. High similarities between the Wollemia and Araucaria genera are observed. Both are characterized by some high relative abundance of tetracyclic compounds with no predominance of other specific diterpenoids.

  5. Uptake of water via branches helps timberline conifers refill embolized xylem in late winter.

    PubMed

    Mayr, Stefan; Schmid, Peter; Laur, Joan; Rosner, Sabine; Charra-Vaskou, Katline; Dämon, Birgit; Hacke, Uwe G

    2014-04-01

    Xylem embolism is a limiting factor for woody species worldwide. Conifers at the alpine timberline are exposed to drought and freeze-thaw stress during winter, which induce potentially lethal embolism. Previous studies indicated that timberline trees survive by xylem refilling. In this study on Picea abies, refilling was monitored during winter and spring seasons and analyzed in the laboratory and in situ experiments, based on hydraulic, anatomical, and histochemical methods. Refilling started in late winter, when the soil was frozen and soil water not available for the trees. Xylem embolism caused up to 86.2% ± 3.1% loss of conductivity and was correlated with the ratio of closed pits. Refilling of xylem as well as recovery in shoot conductance started in February and corresponded with starch accumulation in secondary phloem and in the mesophyll of needles, where we also observed increasing aquaporin densities in the phloem and endodermis. This indicates that active, cellular processes play a role for refilling even under winter conditions. As demonstrated by our experiments, water for refilling was thereby taken up via the branches, likely by foliar water uptake. Our results suggest that refilling is based on water shifts to embolized tracheids via intact xylem, phloem, and parenchyma, whereby aquaporins reduce resistances along the symplastic pathway and aspirated pits facilitate isolation of refilling tracheids. Refilling must be taken into account as a key process in plant hydraulics and in estimating future effects of climate change on forests and alpine tree ecosystems.

  6. A broad survey of hydraulic and mechanical safety in the xylem of conifers.

    PubMed

    Bouche, Pauline S; Larter, Maximilien; Domec, Jean-Christophe; Burlett, Régis; Gasson, Peter; Jansen, Steven; Delzon, Sylvain

    2014-08-01

    Drought-induced forest dieback has been widely reported over the last decades, and the evidence for a direct causal link between survival and hydraulic failure (xylem cavitation) is now well known. Because vulnerability to cavitation is intimately linked to the anatomy of the xylem, the main objective of this study was to better understand the xylem anatomical properties associated with cavitation resistance. An extensive data set of cavitation resistance traits and xylem anatomical properties was developed for 115 conifer species, with special attention given to the micro-morphology of bordered pits. The ratio of torus to pit aperture diameter, so-called torus overlap, increased with increasing cavitation resistance, while the flexibility of the margo does not seem to play a role, suggesting that air-seeding is located at the seal between the aspirated torus and pit aperture. Moreover, punctured tori were reported in various Pinaceae species. Species resistant to cavitation had thicker tracheid walls, while their lumen diameter (conduit size) was only slightly reduced, minimizing the impact on hydraulic conductance. The results also demonstrated (i) the existence of an indirect trade-off between hydraulic safety and mechanical strength; and (ii) a consistency between species distribution and xylem anatomy: species with a wide torus overlap and high valve effects are found in arid environments such as the Mediterranean region.

  7. The effect of elevation, light and water availability on the growth of Sierran conifer seedlings

    SciTech Connect

    Kern, R.A.; Dale, V.H.; Beauchamp, J.J. Oak Ridge National Lab., TN )

    1994-06-01

    The composition of many plant communities will be altered with global change, and this will depend on individual species' abilities to reproduce and to survive under new climate conditions. Two experiments are underday to test the hypothesis that seedling demography is affected by the relative drought and shade tolerances of seven co-occurring species of Sierran conifers. The first experiment is being conducted at three sites in Sequoia National Park, California, elevations 1600 m, 1900 m and 2200 m. At each site, closed canopy [open quotes]shade[close quotes] plots and open canopy [open quotes]gap[close quotes] plots are being used. Seedling growth of each species is compared between light levels and elevations. The second experiment also measures seedling growth in low and high levels, but with four levels of water availability at one elevation (1900 m). Microenvironmental monitoring (soil and air temperature, relative humidity, radiation, and soil moisture) by surrounding mature trees are also being measured in order to develop a mechanistic model of seedling growth and survival.

  8. Predicting Impacts of Future Climate Change on the Distribution of the Widespread Conifer Platycladus orientalis.

    PubMed

    Hu, Xian-Ge; Jin, Yuqing; Wang, Xiao-Ru; Mao, Jian-Feng; Li, Yue

    2015-01-01

    Chinese thuja (Platycladus orientalis) has a wide but fragmented distribution in China. It is an important conifer tree in reforestation and plays important roles in ecological restoration in the arid mountains of northern China. Based on high-resolution environmental data for current and future scenarios, we modeled the present and future suitable habitat for P. orientalis, evaluated the importance of environmental factors in shaping the species' distribution, and identified regions of high risk under climate change scenarios. The niche models showed that P. orientalis has suitable habitat of ca. 4.2×106 km2 across most of eastern China and identified annual temperature, monthly minimum and maximum ultraviolet-B radiation and wet-day frequency as the critical factors shaping habitat availability for P. orientalis. Under the low concentration greenhouse gas emissions scenario, the range of the species may increase as global warming intensifies; however, under the higher concentrations of emissions scenario, we predicted a slight expansion followed by contraction in distribution. Overall, the range shift to higher latitudes and elevations would become gradually more significant. The information gained from this study should be an useful reference for implementing long-term conservation and management strategies for the species. PMID:26132163

  9. Mixed conifer forest mortality and establishment before and after prescribed fire in Sequoia National Park, California

    USGS Publications Warehouse

    Mutch, L.S.; Parsons, D.J.

    1998-01-01

    Pre-and post-burn tree mortality rates, size structure, basal area, and ingrowth were determined for four 1.0 ha mixed conifer forest stands in the Log Creek and Tharp's Creek watersheds of Sequoia National Park. Mean annual mortality between 1986 and 1990 was 0.8% for both watersheds. In the fall of 1990, the Tharp's Creek watershed was treated with a prescribed burn. Between 1991 and 1995, mean annual mortality was 1.4% in the unburned Log Creek watershed and 17.2% in the burned Tharp's Creek watershed. A drought from 1987 to 1992 likely contributed to the mortality increase in the Log Creek watershed. The high mortality in the Tharp's Creek watershed was primarily related to crown scorch from the 1990 fire and was modeled with logistic regression for white fir (Abies concolor [Gord. and Glend.]) and sugar pine (Pinus lambertiana [Dougl.]). From 1989 to 1994, basal area declined an average of 5% per year in the burned Tharp's Creek watershed, compared to average annual increases of less than 1% per year in the unburned Log Creek watershed and in the Tharp's watershed prior to burning. Post-burn size structure was dramatically changed in the Tharp's Creek stands: 75% of trees ???50 cm and 25% of trees >50 cm were killed by the fire.

  10. Capturing spiral radial growth of conifers using the superellipse to model tree-ring geometric shape.

    PubMed

    Shi, Pei-Jian; Huang, Jian-Guo; Hui, Cang; Grissino-Mayer, Henri D; Tardif, Jacques C; Zhai, Li-Hong; Wang, Fu-Sheng; Li, Bai-Lian

    2015-01-01

    Tree-rings are often assumed to approximate a circular shape when estimating forest productivity and carbon dynamics. However, tree rings are rarely, if ever, circular, thereby possibly resulting in under- or over-estimation in forest productivity and carbon sequestration. Given the crucial role played by tree ring data in assessing forest productivity and carbon storage within a context of global change, it is particularly important that mathematical models adequately render cross-sectional area increment derived from tree rings. We modeled the geometric shape of tree rings using the superellipse equation and checked its validation based on the theoretical simulation and six actual cross sections collected from three conifers. We found that the superellipse better describes the geometric shape of tree rings than the circle commonly used. We showed that a spiral growth trend exists on the radial section over time, which might be closely related to spiral grain along the longitudinal axis. The superellipse generally had higher accuracy than the circle in predicting the basal area increment, resulting in an improved estimate for the basal area. The superellipse may allow better assessing forest productivity and carbon storage in terrestrial forest ecosystems. PMID:26528316

  11. Effects of conifer release with glyphosate on summer forage abundance for deer in Maine

    USGS Publications Warehouse

    Vreeland, J.K.; Servello, F.A.; Griffith, B.

    1998-01-01

    Effects of conifer release with glyphosate on summer forage availability for large herbivores in northern forests have received relatively little study. We determined effects of glyphosate treatment of clearcuts on abundance of summer foods for white-tailed deer (Odocoileus virginianus) at 1 and 7-10 years posttreatment. We measured the abundance (percent cover in a 0- to 1.8-m height stratum) of five forage classes for deer (leaves of deciduous trees, leaves of deciduous shrubs, forbs, grasses, ferns) on 12 clearcuts (six treated, six untreated) to determine 1-year effects and on 10 clearcuts (five treated, five untreated) to determine 7- to 10-year effects. Abundance of leaves of deciduous trees was greater on untreated sites (38 versus 11%) at 1 year posttreatment, but the difference was less (18 versus 12%) at 7-10 years posttreatment (age x treatment interaction, P = 0.005). Leaves of deciduous shrubs exhibited a similar pattern. Abundance of forbs was similar (13-14%) at 1 year posttreatment but greater on treated sites (29 versus 15%) at 7-10 years posttreatment (P = 0.03). Grasses and ferns were less abundant than other forage classes. Overall, glyphosate application initially decreased the abundance of leaves of deciduous trees and shrubs used as food in summer, but the longer term positive effects on forb abundance may result in little net change in overall habitat value.

  12. A broad survey of hydraulic and mechanical safety in the xylem of conifers

    PubMed Central

    Bouche, Pauline S.; Larter, Maximilien; Domec, Jean-Christophe; Burlett, Régis; Gasson, Peter; Jansen, Steven; Delzon, Sylvain

    2014-01-01

    Drought-induced forest dieback has been widely reported over the last decades, and the evidence for a direct causal link between survival and hydraulic failure (xylem cavitation) is now well known. Because vulnerability to cavitation is intimately linked to the anatomy of the xylem, the main objective of this study was to better understand the xylem anatomical properties associated with cavitation resistance. An extensive data set of cavitation resistance traits and xylem anatomical properties was developed for 115 conifer species, with special attention given to the micro-morphology of bordered pits. The ratio of torus to pit aperture diameter, so-called torus overlap, increased with increasing cavitation resistance, while the flexibility of the margo does not seem to play a role, suggesting that air-seeding is located at the seal between the aspirated torus and pit aperture. Moreover, punctured tori were reported in various Pinaceae species. Species resistant to cavitation had thicker tracheid walls, while their lumen diameter (conduit size) was only slightly reduced, minimizing the impact on hydraulic conductance. The results also demonstrated (i) the existence of an indirect trade-off between hydraulic safety and mechanical strength; and (ii) a consistency between species distribution and xylem anatomy: species with a wide torus overlap and high valve effects are found in arid environments such as the Mediterranean region. PMID:24916072

  13. Effect of canopy structure and the presence of snow on the albedo of boreal conifer forests

    NASA Astrophysics Data System (ADS)

    Ni, Wenge; Woodcock, Curtis E.

    2000-05-01

    A Geometric-Optical and Radiative Transfer (GORT) approach for modeling the radiation regime within plant canopies is capable of predicting temporal variation in the albedo of boreal conifer forests. Model predictions of daily surface albedo patterns and reflected solar radiation during the winter and summer seasons were validated using field measurements from two forest stands in the northern study area of BOReal Ecosystem-Atmosphere Study (BOREAS) in 1995. The model is able to predict the "W" shape for the daily albedo over the sparse old jack pine forest stand during the snow season and the "bowl" shape of daily albedo during clear days in the summer. Results immediately following new snow and at the end of the snowmelt season indicate the sensitivity of overall forest albedos to the albedo of snow. Incorporation of time-varying values for snow albedo may improve future efforts to estimate forest albedos in the winter. Forest albedos are a complicated function of the canopy structure, the presence or absence of snow on the ground and the angular distribution of irradiance. These effects differ for the visible, near-infrared and midinfrared portions of the solar spectrum. Forest albedos vary dramatically as a function of canopy cover when snow covers the ground, but very little when snow is not present. It is found that for tree cover over about 70%, the presence of snow has little effect on albedo.

  14. Reclamation of mined organic soils in northern Minnesota to selected conifers

    SciTech Connect

    Schmitt, M.D.C.

    1983-01-01

    In a greenhouse experiment designed to evaluate the capacity of residual organic soils from mined peatland sites to support commercially valuable conifers under various fertilization regimes, the six month height growth and dry weight production of Scotch pine, black, white, and Norway spruce was dependent upon the nature and properties of the residual organic soils to be reclaimed, the species selected to revegetate these sites, the type and amount of fertilizer treatments applied, and interactions between these factors. On a highly acid, nutrient poor Fibrist, only Scotch pine seedlings exhibited adequate growth, but their performance appeared to be limited by natural and fertilizer induced soil acidity. On a Ca rich, near neutral Hemist, Scotch pine growth was adequate and unaffected by fertilization. However, spruce growth was vigorous only under a fertilizer treatment containing micronutrients plus a high rate of NPK. Although there is little doubt that residual organic soils from mined peatland sites can be used for forest production, there are important differences between sites requiring that each be considered individually before reclamation procedures are initiated.

  15. Negligible influence of spatial autocorrelation in the assessment of fire effects in a mixed conifer forest

    USGS Publications Warehouse

    van Mantgem, P.J.; Schwilk, D.W.

    2009-01-01

    Fire is an important feature of many forest ecosystems, although the quantification of its effects is compromised by the large scale at which fire occurs and its inherent unpredictability. A recurring problem is the use of subsamples collected within individual burns, potentially resulting in spatially autocorrelated data. Using subsamples from six different fires (and three unburned control areas) we show little evidence for strong spatial autocorrelation either before or after burning for eight measures of forest conditions (both fuels and vegetation). Additionally, including a term for spatially autocorrelated errors provided little improvement for simple linear models contrasting the effects of early versus late season burning. While the effects of spatial autocorrelation should always be examined, it may not always greatly influence assessments of fire effects. If high patch scale variability is common in Sierra Nevada mixed conifer forests, even following more than a century of fire exclusion, treatments designed to encourage further heterogeneity in forest conditions prior to the reintroduction of fire will likely be unnecessary.

  16. Long-term effect on some chemical parameter and microbial diversity in a conifer forest soil

    NASA Astrophysics Data System (ADS)

    Iglesias, T.; Iglesias, M.; Francisco-Álvarez, R.; Ramírez, M.; Fernández-Bermejo, M. C.

    2009-04-01

    Soil microbiota are one of the soil components most affected by wildfires. The data from the present study were obtained from a conifer forest soil at Sierra de Gredos (Ávila, central Spain) twenty years after fire of low-to-moderate intensity. A set of soil characteristics indicated the extent to which the spontaneous recovery of the soil is produced as a result of vegetation regrowth. Ten months after fire a strong increase in soil pH, organic C and N, and exchangeable Ca and K, with respect the control soil. Eighteen years after this fire it was observed a decrease of soil organic C and N, whereas other variables such as pH, exchangeable Ca and K were slightly increased with respect to control soil. Is summe a change in soil microbiota was observed due to wildfire, with a decrease in fungi and bacteria population, Also some changes in microbial community was detected, Key words: Forest Fire, soil microbiology, chemical soil properties

  17. A broad survey of hydraulic and mechanical safety in the xylem of conifers.

    PubMed

    Bouche, Pauline S; Larter, Maximilien; Domec, Jean-Christophe; Burlett, Régis; Gasson, Peter; Jansen, Steven; Delzon, Sylvain

    2014-08-01

    Drought-induced forest dieback has been widely reported over the last decades, and the evidence for a direct causal link between survival and hydraulic failure (xylem cavitation) is now well known. Because vulnerability to cavitation is intimately linked to the anatomy of the xylem, the main objective of this study was to better understand the xylem anatomical properties associated with cavitation resistance. An extensive data set of cavitation resistance traits and xylem anatomical properties was developed for 115 conifer species, with special attention given to the micro-morphology of bordered pits. The ratio of torus to pit aperture diameter, so-called torus overlap, increased with increasing cavitation resistance, while the flexibility of the margo does not seem to play a role, suggesting that air-seeding is located at the seal between the aspirated torus and pit aperture. Moreover, punctured tori were reported in various Pinaceae species. Species resistant to cavitation had thicker tracheid walls, while their lumen diameter (conduit size) was only slightly reduced, minimizing the impact on hydraulic conductance. The results also demonstrated (i) the existence of an indirect trade-off between hydraulic safety and mechanical strength; and (ii) a consistency between species distribution and xylem anatomy: species with a wide torus overlap and high valve effects are found in arid environments such as the Mediterranean region. PMID:24916072

  18. Genetic evaluation of the breeding population of a valuable reforestation conifer Platycladus orientalis (Cupressaceae)

    NASA Astrophysics Data System (ADS)

    Jin, Yuqing; Ma, Yongpeng; Wang, Shun; Hu, Xian-Ge; Huang, Li-Sha; Li, Yue; Wang, Xiao-Ru; Mao, Jian-Feng

    2016-10-01

    Platycladus orientalis, a widespread conifer with long lifespan and significant adaptability. It is much used in reforestation in north China and commonly planted in central Asia. With the increasing demand for plantation forest in central to north China, breeding programs are progressively established for this species. Efficient use of breeding resources requires good understanding of the genetic value of the founder breeding materials. This study investigated the distribution of genetic variation in 192 elite trees collected for the breeding program for the central range of the species. We developed first set of 27 polymorphic EST-derived SSR loci for the species from transcriptome/genome data. After examination of amplification quality, 10 loci were used to evaluate the genetic variation in the breeding population. We found moderate genetic diversity (average He = 0.348) and low population differentiation (Fst = 0.011). Extensive admixture and no significant geographic population structure characterized this set of collections. Our analyses of the diversity and population structure are important steps toward a long-term sustainable deployment of the species and provide valuable genetic information for conservation and breeding applications.

  19. Multi-scale predictions of massive conifer mortality due to chronic temperature rise

    NASA Astrophysics Data System (ADS)

    McDowell, N. G.; Williams, A. P.; Xu, C.; Pockman, W. T.; Dickman, L. T.; Sevanto, S.; Pangle, R.; Limousin, J.; Plaut, J.; Mackay, D. S.; Ogee, J.; Domec, J. C.; Allen, C. D.; Fisher, R. A.; Jiang, X.; Muss, J. D.; Breshears, D. D.; Rauscher, S. A.; Koven, C.

    2016-03-01

    Global temperature rise and extremes accompanying drought threaten forests and their associated climatic feedbacks. Our ability to accurately simulate drought-induced forest impacts remains highly uncertain in part owing to our failure to integrate physiological measurements, regional-scale models, and dynamic global vegetation models (DGVMs). Here we show consistent predictions of widespread mortality of needleleaf evergreen trees (NET) within Southwest USA by 2100 using state-of-the-art models evaluated against empirical data sets. Experimentally, dominant Southwest USA NET species died when they fell below predawn water potential (Ψpd) thresholds (April-August mean) beyond which photosynthesis, hydraulic and stomatal conductance, and carbohydrate availability approached zero. The evaluated regional models accurately predicted NET Ψpd, and 91% of predictions (10 out of 11) exceeded mortality thresholds within the twenty-first century due to temperature rise. The independent DGVMs predicted >=50% loss of Northern Hemisphere NET by 2100, consistent with the NET findings for Southwest USA. Notably, the global models underestimated future mortality within Southwest USA, highlighting that predictions of future mortality within global models may be underestimates. Taken together, the validated regional predictions and the global simulations predict widespread conifer loss in coming decades under projected global warming.

  20. Histology and cell wall biochemistry of stone cells in the physical defence of conifers against insects.

    PubMed

    Whitehill, Justin G A; Henderson, Hannah; Schuetz, Mathias; Skyba, Oleksandr; Yuen, Macaire Man Saint; King, John; Samuels, A Lacey; Mansfield, Shawn D; Bohlmann, Jörg

    2016-08-01

    Conifers possess an array of physical and chemical defences against stem-boring insects. Stone cells provide a physical defence associated with resistance against bark beetles and weevils. In Sitka spruce (Picea sitchensis), abundance of stone cells in the cortex of apical shoots is positively correlated with resistance to white pine weevil (Pissodes strobi). We identified histological, biochemical and molecular differences in the stone cell phenotype of weevil resistant (R) or susceptible (S) Sitka spruce genotypes. R trees displayed significantly higher quantities of cortical stone cells near the apical shoot node, the primary site for weevil feeding. Lignin, cellulose, xylan and mannan were the most abundant components of stone cell secondary walls, respectively. Lignin composition of stone cells isolated from R trees contained a higher percentage of G-lignin compared with S trees. Transcript profiling revealed higher transcript abundance in the R genotype of coumarate 3-hydroxylase, a key monolignol biosynthetic gene. Developing stone cells in current year apical shoots incorporated fluorescent-tagged monolignol into the secondary cell wall, while mature stone cells of previous year apical shoots did not. Stone cell development is an ephemeral process, and fortification of shoot tips in R trees is an effective strategy against insect feeding.

  1. Genetic evaluation of the breeding population of a valuable reforestation conifer Platycladus orientalis (Cupressaceae)

    PubMed Central

    Jin, Yuqing; Ma, Yongpeng; Wang, Shun; Hu, Xian-Ge; Huang, Li-Sha; Li, Yue; Wang, Xiao-Ru; Mao, Jian-Feng

    2016-01-01

    Platycladus orientalis, a widespread conifer with long lifespan and significant adaptability. It is much used in reforestation in north China and commonly planted in central Asia. With the increasing demand for plantation forest in central to north China, breeding programs are progressively established for this species. Efficient use of breeding resources requires good understanding of the genetic value of the founder breeding materials. This study investigated the distribution of genetic variation in 192 elite trees collected for the breeding program for the central range of the species. We developed first set of 27 polymorphic EST-derived SSR loci for the species from transcriptome/genome data. After examination of amplification quality, 10 loci were used to evaluate the genetic variation in the breeding population. We found moderate genetic diversity (average He = 0.348) and low population differentiation (Fst = 0.011). Extensive admixture and no significant geographic population structure characterized this set of collections. Our analyses of the diversity and population structure are important steps toward a long-term sustainable deployment of the species and provide valuable genetic information for conservation and breeding applications. PMID:27721449

  2. Abscisic Acid Mediates a Divergence in the Drought Response of Two Conifers1[W][OA

    PubMed Central

    Brodribb, Timothy J.; McAdam, Scott A.M.

    2013-01-01

    During water stress, stomatal closure occurs as water tension and levels of abscisic acid (ABA) increase in the leaf, but the interaction between these two drivers of stomatal aperture is poorly understood. We investigate the dynamics of water potential, ABA, and stomatal conductance during the imposition of water stress on two drought-tolerant conifer species with contrasting stomatal behavior. Rapid rehydration of excised shoots was used as a means of differentiating the direct influences of ABA and water potential on stomatal closure. Pinus radiata (Pinaceae) was found to exhibit ABA-driven stomatal closure during water stress, resulting in strongly isohydric regulation of water loss. By contrast, stomatal closure in Callitris rhomboidea (Cupressaceae) was initiated by elevated foliar ABA, but sustained water stress saw a marked decline in ABA levels and a shift to water potential-driven stomatal closure. The transition from ABA to water potential as the primary driver of stomatal aperture allowed C. rhomboidea to rapidly recover gas exchange after water-stressed plants were rewatered, and was associated with a strongly anisohydric regulation of water loss. These two contrasting mechanisms of stomatal regulation function in combination with xylem vulnerability to produce highly divergent strategies of water management. Species-specific ABA dynamics are proposed as a central component of drought survival and ecology. PMID:23709665

  3. Conifers in cold environments synchronize maximum growth rate of tree-ring formation with day length.

    PubMed

    Rossi, Sergio; Deslauriers, Annie; Anfodillo, Tommaso; Morin, Hubert; Saracino, Antonio; Motta, Renzo; Borghetti, Marco

    2006-01-01

    Intra-annual radial growth rates and durations in trees are reported to differ greatly in relation to species, site and environmental conditions. However, very similar dynamics of cambial activity and wood formation are observed in temperate and boreal zones. Here, we compared weekly xylem cell production and variation in stem circumference in the main northern hemisphere conifer species (genera Picea, Pinus, Abies and Larix) from 1996 to 2003. Dynamics of radial growth were modeled with a Gompertz function, defining the upper asymptote (A), x-axis placement (beta) and rate of change (kappa). A strong linear relationship was found between the constants beta and kappa for both types of analysis. The slope of the linear regression, which corresponds to the time at which maximum growth rate occurred, appeared to converge towards the summer solstice. The maximum growth rate occurred around the time of maximum day length, and not during the warmest period of the year as previously suggested. The achievements of photoperiod could act as a growth constraint or a limit after which the rate of tree-ring formation tends to decrease, thus allowing plants to safely complete secondary cell wall lignification before winter.

  4. Capturing spiral radial growth of conifers using the superellipse to model tree-ring geometric shape

    PubMed Central

    Shi, Pei-Jian; Huang, Jian-Guo; Hui, Cang; Grissino-Mayer, Henri D.; Tardif, Jacques C.; Zhai, Li-Hong; Wang, Fu-Sheng; Li, Bai-Lian

    2015-01-01

    Tree-rings are often assumed to approximate a circular shape when estimating forest productivity and carbon dynamics. However, tree rings are rarely, if ever, circular, thereby possibly resulting in under- or over-estimation in forest productivity and carbon sequestration. Given the crucial role played by tree ring data in assessing forest productivity and carbon storage within a context of global change, it is particularly important that mathematical models adequately render cross-sectional area increment derived from tree rings. We modeled the geometric shape of tree rings using the superellipse equation and checked its validation based on the theoretical simulation and six actual cross sections collected from three conifers. We found that the superellipse better describes the geometric shape of tree rings than the circle commonly used. We showed that a spiral growth trend exists on the radial section over time, which might be closely related to spiral grain along the longitudinal axis. The superellipse generally had higher accuracy than the circle in predicting the basal area increment, resulting in an improved estimate for the basal area. The superellipse may allow better assessing forest productivity and carbon storage in terrestrial forest ecosystems. PMID:26528316

  5. Uptake of water via branches helps timberline conifers refill embolized xylem in late winter.

    PubMed

    Mayr, Stefan; Schmid, Peter; Laur, Joan; Rosner, Sabine; Charra-Vaskou, Katline; Dämon, Birgit; Hacke, Uwe G

    2014-04-01

    Xylem embolism is a limiting factor for woody species worldwide. Conifers at the alpine timberline are exposed to drought and freeze-thaw stress during winter, which induce potentially lethal embolism. Previous studies indicated that timberline trees survive by xylem refilling. In this study on Picea abies, refilling was monitored during winter and spring seasons and analyzed in the laboratory and in situ experiments, based on hydraulic, anatomical, and histochemical methods. Refilling started in late winter, when the soil was frozen and soil water not available for the trees. Xylem embolism caused up to 86.2% ± 3.1% loss of conductivity and was correlated with the ratio of closed pits. Refilling of xylem as well as recovery in shoot conductance started in February and corresponded with starch accumulation in secondary phloem and in the mesophyll of needles, where we also observed increasing aquaporin densities in the phloem and endodermis. This indicates that active, cellular processes play a role for refilling even under winter conditions. As demonstrated by our experiments, water for refilling was thereby taken up via the branches, likely by foliar water uptake. Our results suggest that refilling is based on water shifts to embolized tracheids via intact xylem, phloem, and parenchyma, whereby aquaporins reduce resistances along the symplastic pathway and aspirated pits facilitate isolation of refilling tracheids. Refilling must be taken into account as a key process in plant hydraulics and in estimating future effects of climate change on forests and alpine tree ecosystems. PMID:24521876

  6. Evidence for foliar endophytic nitrogen fixation in a widely distributed subalpine conifer.

    PubMed

    Moyes, Andrew B; Kueppers, Lara M; Pett-Ridge, Jennifer; Carper, Dana L; Vandehey, Nick; O'Neil, James; Frank, A Carolin

    2016-04-01

    Coniferous forest nitrogen (N) budgets indicate unknown sources of N. A consistent association between limber pine (Pinus flexilis) and potential N2 -fixing acetic acid bacteria (AAB) indicates that native foliar endophytes may supply subalpine forests with N. To assess whether the P. flexilis-AAB association is consistent across years, we re-sampled P. flexilis twigs at Niwot Ridge, CO and characterized needle endophyte communities via 16S rRNA Illumina sequencing. To investigate whether endophytes have access to foliar N2 , we incubated twigs with (13) N2 -enriched air and imaged radioisotope distribution in needles, the first experiment of its kind using (13) N. We used the acetylene reduction assay to test for nitrogenase activity within P. flexilis twigs four times from June to September. We found evidence for N2 fixation in P. flexilis foliage. N2 diffused readily into needles and nitrogenase activity was positive across sampling dates. We estimate that this association could provide 6.8-13.6 μg N m(-2)  d(-1) to P. flexilis stands. AAB dominated the P. flexilis needle endophyte community. We propose that foliar endophytes represent a low-cost, evolutionarily stable N2 -fixing strategy for long-lived conifers. This novel source of biological N2 fixation has fundamental implications for understanding forest N budgets.

  7. Sea sand disruption method (SSDM) as a valuable tool for isolating essential oil components from conifers.

    PubMed

    Dawidowicz, Andrzej L; Czapczyńska, Natalia B

    2011-11-01

    Essential oils are one of nature's most precious gifts with surprisingly potent and outstanding properties. Coniferous oils, for instance, are nowadays being used extensively to treat or prevent many types of infections, modify immune responses, soothe inflammations, stabilize moods, and to help ease all forms of non-acute pain. Given the broad spectrum of usage of coniferous essential oils, a fast, safe, simple, and efficient sample-preparation method is needed in the estimation procedure of essential oil components in fresh plant material. Generally, the time- and energy-consuming steam distillation (SD) is applied for this purpose. This paper will compare SD, pressurized liquid extraction (PLE), matrix solid-phase dispersion (MSPD), and the sea sand disruption method (SSDM) as isolation techniques to obtain aroma components from Scots pine (Pinus sylvestris), spruce (Picea abies), and Douglas fir (Pseudotsuga menziesii). According to the obtained data, SSDM is the most efficient sample preparation method in determining the essential oil composition of conifers. Moreover, SSDM requires small organic solvent amounts and a short extraction time, which makes it an advantageous alternative procedure for the routine analysis of coniferous oils. The superiority of SSDM over MSPD efficiency is ascertained, as there are no chemical interactions between the plant cell components and the sand. This fact confirms the reliability and efficacy of SSDM for the analysis of volatile oil components. PMID:22083917

  8. Evidence for foliar endophytic nitrogen fixation in a widely distributed subalpine conifer.

    PubMed

    Moyes, Andrew B; Kueppers, Lara M; Pett-Ridge, Jennifer; Carper, Dana L; Vandehey, Nick; O'Neil, James; Frank, A Carolin

    2016-04-01

    Coniferous forest nitrogen (N) budgets indicate unknown sources of N. A consistent association between limber pine (Pinus flexilis) and potential N2 -fixing acetic acid bacteria (AAB) indicates that native foliar endophytes may supply subalpine forests with N. To assess whether the P. flexilis-AAB association is consistent across years, we re-sampled P. flexilis twigs at Niwot Ridge, CO and characterized needle endophyte communities via 16S rRNA Illumina sequencing. To investigate whether endophytes have access to foliar N2 , we incubated twigs with (13) N2 -enriched air and imaged radioisotope distribution in needles, the first experiment of its kind using (13) N. We used the acetylene reduction assay to test for nitrogenase activity within P. flexilis twigs four times from June to September. We found evidence for N2 fixation in P. flexilis foliage. N2 diffused readily into needles and nitrogenase activity was positive across sampling dates. We estimate that this association could provide 6.8-13.6 μg N m(-2)  d(-1) to P. flexilis stands. AAB dominated the P. flexilis needle endophyte community. We propose that foliar endophytes represent a low-cost, evolutionarily stable N2 -fixing strategy for long-lived conifers. This novel source of biological N2 fixation has fundamental implications for understanding forest N budgets. PMID:27000956

  9. Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands

    USGS Publications Warehouse

    Falcon-Lang, H. J.; Nelson, W.J.; Elrick, S.; Looy, C.V.; Ames, P.R.; DiMichele, W.A.

    2009-01-01

    The idea that the Pennsylvanian tropical lowlands were temporally dominated by rainforest (i.e., the Coal Forest) is deeply ingrained in the literature. Here we challenge two centuries of research by suggesting that this concept is based on a taphonomic artifact, and that seasonally dry vegetation dominated instead. This controversial finding arises from the discovery of a new middle Pennsylvanian (Moscovian) fossil plant assemblage in southeast Illinois, United States. The assemblage, which contains xerophytic walchian conifers, occurs in channels incised into a calcic Vertisol below the Baker Coal. These plants grew on seasonally dry tropical lowlands inferred to have developed during a glacial phase. This xerophytic flora differs markedly from that of the typical clubmoss-dominated Coal Forest developed during deglaciation events. Although preserved only very rarely, we argue that such xerophytic floras were temporally as dominant, and perhaps more dominant, than the iconic Coal Forests, which are overrepresented in the fossil record due to taphonomic megabias. These findings require the iconography of Pennsylvanian tropical lowlands to be redrawn. ?? 2009 Geological Society of America.

  10. Multi-scale predictions of massive conifer mortality due to chronic temperature rise

    USGS Publications Warehouse

    McDowell, Nathan G.; Williams, A.P.; Xu, C.; Pockman, W. T.; Dickman, L. T.; Sevanto, S.; Pangle, R.; Limousin, J.; Plaut, J.J.; Mackay, D.S.; Ogee, J.; Domec, Jean-Christophe; Allen, Craig D.; Fisher, Rosie A.; Jiang, X.; Muss, J.D.; Breshears, D.D.; Rauscher, Sara A.; Koven, C.

    2015-01-01

    Global temperature rise and extremes accompanying drought threaten forests and their associated climatic feedbacks. Our ability to accurately simulate drought-induced forest impacts remains highly uncertain in part owing to our failure to integrate physiological measurements, regional-scale models, and dynamic global vegetation models (DGVMs). Here we show consistent predictions of widespread mortality of needleleaf evergreen trees (NET) within Southwest USA by 2100 using state-of-the-art models evaluated against empirical data sets. Experimentally, dominant Southwest USA NET species died when they fell below predawn water potential (Ψpd) thresholds (April–August mean) beyond which photosynthesis, hydraulic and stomatal conductance, and carbohydrate availability approached zero. The evaluated regional models accurately predicted NET Ψpd, and 91% of predictions (10 out of 11) exceeded mortality thresholds within the twenty-first century due to temperature rise. The independent DGVMs predicted ≥50% loss of Northern Hemisphere NET by 2100, consistent with the NET findings for Southwest USA. Notably, the global models underestimated future mortality within Southwest USA, highlighting that predictions of future mortality within global models may be underestimates. Taken together, the validated regional predictions and the global simulations predict widespread conifer loss in coming decades under projected global warming.

  11. Predicting Impacts of Future Climate Change on the Distribution of the Widespread Conifer Platycladus orientalis

    PubMed Central

    Hu, Xian-Ge; Jin, Yuqing; Wang, Xiao-Ru; Mao, Jian-Feng; Li, Yue

    2015-01-01

    Chinese thuja (Platycladus orientalis) has a wide but fragmented distribution in China. It is an important conifer tree in reforestation and plays important roles in ecological restoration in the arid mountains of northern China. Based on high-resolution environmental data for current and future scenarios, we modeled the present and future suitable habitat for P. orientalis, evaluated the importance of environmental factors in shaping the species´ distribution, and identified regions of high risk under climate change scenarios. The niche models showed that P. orientalis has suitable habitat of ca. 4.2×106 km2 across most of eastern China and identified annual temperature, monthly minimum and maximum ultraviolet-B radiation and wet-day frequency as the critical factors shaping habitat availability for P. orientalis. Under the low concentration greenhouse gas emissions scenario, the range of the species may increase as global warming intensifies; however, under the higher concentrations of emissions scenario, we predicted a slight expansion followed by contraction in distribution. Overall, the range shift to higher latitudes and elevations would become gradually more significant. The information gained from this study should be an useful reference for implementing long-term conservation and management strategies for the species. PMID:26132163

  12. Scaling of phloem structure and optimality of photoassimilate transport in conifer needles

    PubMed Central

    Ronellenfitsch, Henrik; Liesche, Johannes; Jensen, Kaare H.; Holbrook, N. Michele; Schulz, Alexander; Katifori, Eleni

    2015-01-01

    The phloem vascular system facilitates transport of energy-rich sugar and signalling molecules in plants, thus permitting long-range communication within the organism and growth of non-photosynthesizing organs such as roots and fruits. The flow is driven by osmotic pressure, generated by differences in sugar concentration between distal parts of the plant. The phloem is an intricate distribution system, and many questions about its regulation and structural diversity remain unanswered. Here, we investigate the phloem structure in the simplest possible geometry: a linear leaf, found, for example, in the needles of conifer trees. We measure the phloem structure in four tree species representing a diverse set of habitats and needle sizes, from 1 (Picea omorika) to 35 cm (Pinus palustris). We show that the phloem shares common traits across these four species and find that the size of its conductive elements obeys a power law. We present a minimal model that accounts for these common traits and takes into account the transport strategy and natural constraints. This minimal model predicts a power law phloem distribution consistent with transport energy minimization, suggesting that energetics are more important than translocation speed at the leaf level. PMID:25567645

  13. Bark heat resistance of small trees in Californian mixed conifer forests: Testing some model assumptions

    USGS Publications Warehouse

    van Mantgem, Phillip J.; Schwartz, Mark

    2003-01-01

    An essential component to models of fire-caused tree mortality is an assessment of cambial damage. Cambial heat resistance has been traditionally measured in large overstory trees with thick bark, although small trees have thinner bark and thus are more sensitive to fire. We undertook this study to determine if current models of bark heat transfer are applicable to small trees (<20 cm diameter at breast height (dbh)). We performed this work in situ on four common species in the mixed conifer forests of the Sierra Nevada, California.The allometric relationship between bole diameter and bark thickness for each species was linear, even for very small trees (5 cm dbh). Heating experiments demonstrated that bark thickness was the primary determinant of cambial heat resistance. We found only slight, but statistically significant, among species differences in bark thermal properties. Our most significant finding was that small trees were more resistant to heating than expected from commonly used models of bark heat transfer. Our results may differ from those of existing models because we found smaller trees to have a greater proportion of inner bark, which appears to have superior insulating properties compared to outer bark. From a management perspective, growth projections suggest that a 50-year fire-free interval may allow some fire intolerant species to achieve at least some degree of cambial heat resistance in the Sierra Nevada.

  14. Mega-fire Recovery in Dry Conifer Forests of the Interior West

    NASA Astrophysics Data System (ADS)

    Malone, S. L.; Fornwalt, P.; Chambers, M. E.; Battaglia, M.

    2015-12-01

    Wildfire is a complex landscape process with great uncertainty in whether trends in size and severity are shifting trajectories for ecosystem recovery that are outside of the historical range of variability. Considering that wildfire size and severity is likely to increase into the future with a drier climate, it is important that we understand wildfire effects and ecosystem recovery. To evaluate how ecosystems recover from wildfire we measured spatial patterns in regeneration and mapped tree refugia within mega-fire perimeters (Hayman, Jasper, Bobcat, and Grizzly Gulch) in ponderosa pine (Pinus ponderosa) dominated forest. On average, high severity fire effects accounted for > 15% of burned area and increased with fire size. Areas with high severity fire effects contained 1 - 15% tree refugia cover, compared to 37 - 70% observed in low severity areas . Large high severity patches with low coverage of tree refugia, were more frequent in larger fires and regeneration distances required to initiate forest recovery far exceeded 1.5 canopy height or 200 m, distances where the vast majority of regeneration is likely to arise. Using a recovery model driven by distance, we estimate recovery times between 300 to > 1000 years for these mega-fires. In Western dry conifer forests, large patches of stand replacing fire are likely to lead to uneven aged forest and very long recovery times.

  15. Recent growth of conifer species of western North America: Assessing spatial patterns of radial growth trends

    USGS Publications Warehouse

    McKenzie, D.; Hessl, Amy E.; Peterson, D.L.

    2001-01-01

    We explored spatial patterns of low-frequency variability in radial tree growth among western North American conifer species and identified predictors of the variability in these patterns. Using 185 sites from the International Tree-Ring Data Bank, each of which contained 10a??60 raw ring-width series, we rebuilt two chronologies for each site, using two conservative methods designed to retain any low-frequency variability associated with recent environmental change. We used factor analysis to identify regional low-frequency patterns in site chronologies and estimated the slope of the growth trend since 1850 at each site from a combination of linear regression and time-series techniques. This slope was the response variable in a regression-tree model to predict the effects of environmental gradients and species-level differences on growth trends. Growth patterns at 27 sites from the American Southwest were consistent with quasi-periodic patterns of drought. Either 12 or 32 of the 185 sites demonstrated patterns of increasing growth between 1850 and 1980 A.D., depending on the standardization technique used. Pronounced growth increases were associated with high-elevation sites (above 3000 m) and high-latitude sites in maritime climates. Future research focused on these high-elevation and high-latitude sites should address the precise mechanisms responsible for increased 20th century growth.

  16. Evaluation of secretome of highly efficient lignocellulolytic Penicillium sp. Dal 5 isolated from rhizosphere of conifers.

    PubMed

    Rai, Rohit; Kaur, Baljit; Singh, Surender; Di Falco, Macros; Tsang, Adrian; Chadha, B S

    2016-09-01

    Penicillium sp. (Dal 5) isolated from rhizosphere of conifers from Dalhousie (Himachal Pradesh, India) was found to be an efficient cellulolytic strain. The culture under shake flask on CWR (cellulose, wheat bran and rice straw) medium produced appreciably higher levels of endoglucanase (35.69U/ml), β-glucosidase (4.20U/ml), cellobiohydrolase (2.86U/ml), FPase (1.2U/ml) and xylanase (115U/ml) compared to other Penicillium strains reported in literature. The mass spectroscopy analysis of Penicillium sp. Dal 5 secretome identified 108 proteins constituting an array of CAZymes including glycosyl hydrolases (GH) belonging to 24 different families, polysaccharide lyases (PL), carbohydrate esterases (CE), lytic polysaccharide mono-oxygenases (LPMO) in addition to swollenin and a variety of carbohydrate binding modules (CBM) indicating an elaborate genetic potential of this strain for hydrolysis of lignocellulosics. Further, the culture extract was evaluated for hydrolysis of alkali treated rice straw, wheat straw, bagasse and corn cob at 10% substrate loading rate. PMID:27341464

  17. Responses of leaf structure and photosynthetic properties to intra-canopy light gradients: a common garden test with four broadleaf deciduous angiosperm and seven evergreen conifer tree species.

    PubMed

    Wyka, Tomasz P; Oleksyn, J; Zytkowiak, R; Karolewski, P; Jagodziński, A M; Reich, P B

    2012-09-01

    Spectra of leaf traits in northern temperate forest canopies reflect major differences in leaf longevity between evergreen conifers and deciduous broadleaf angiosperms, as well as plastic modifications caused by within-crown shading. We investigated (1) whether long-lived conifer leaves exhibit similar intra-canopy plasticity as short-lived broadleaves, and (2) whether global interspecific relationships between photosynthesis, nitrogen, and leaf structure identified for sun leaves adequately describe leaves differentiated in response to light gradients. We studied structural and photosynthetic properties of intra-tree sun and shade foliage in adult trees of seven conifer and four broadleaf angiosperm species in a common garden in Poland. Shade leaves exhibited lower leaf mass-per-area (LMA) than sun leaves; however, the relative difference was smaller in conifers than in broadleaves. In broadleaves, LMA was correlated with lamina thickness and tissue density, while in conifers, it was correlated with thickness but not density. In broadleaves, but not in conifers, reduction of lamina thickness was correlated with a thinner palisade layer. The more conservative adjustment of conifer leaves could result from a combination of phylogenetic constraints, contrasting leaf anatomies and shoot geometries, but also from functional requirements of long-lived foliage. Mass-based nitrogen concentration (N(mass)) was similar between sun and shade leaves, and was lower in conifers than in deciduous broadleaved species. Given this, the smaller LMA in shade corresponded with a lower area-based N concentration (N(area)). In evergreen conifers, LMA and N(area) were less powerful predictors of area-based photosynthetic rate (A (max(area))) in comparison with deciduous broadleaved angiosperms. Multiple regression for sun and shade leaves showed that, in each group, A (max(mass)) was related to N(mass) but not to LMA, whereas LMA became a significant codeterminant of A (max(mass)) in

  18. Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic-Jurassic transition.

    PubMed

    Kürschner, Wolfram M; Batenburg, Sietske J; Mander, Luke

    2013-10-01

    Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic-Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis.

  19. Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

    PubMed Central

    Kürschner, Wolfram M.; Batenburg, Sietske J.; Mander, Luke

    2013-01-01

    Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic–Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis. PMID:23926159

  20. Growth, allometry and shade tolerance of understory saplings of four subalpine conifers in central Japan.

    PubMed

    Takahashi, Koichi; Obata, Yoshiko

    2014-03-01

    The conifers Abies veitchii, A. mariesii, Picea jezoensis var. hondoensis, Tsuga diversifolia dominate in subalpine forests in central Japan. We expected that species differences in shade tolerance and in aboveground and belowground architecture are important for their coexistence. We examined net production and carbon allocation of understory saplings. Although the four species allocated similar amounts of biomass to roots at a given trunk height, the root-zone area of T. diversifolia was greater than that of the three other species. T. diversifolia often dominates shallow soil sites, such as ridge and rocky slopes, and, therefore, a wide spread of lateral roots would be an adaptation to such edaphic conditions. Crown width and leaf and branch mass were greatest for T. diversifolia and A. mariesii, followed in order by A. veitchii and P. jezoensis var. hondoensis. Although leaf mass of P. jezoensis var. hondoensis was lowest among the four species, species differences were not found in the net production per sapling because net production per leaf mass was greatest for P. jezoensis var. hondoensis. The leaf lifespan was longer in the order A. mariesii, T. diversifolia, P. jezoensis var. hondoensis and A. veitchii. The minimum rate of net production per leaf mass required to maintain the current sapling leaf mass (MRNP(LM)) was lowest in A. mariesii and T. diversifolia, and increased in the order of A. veitchii and P. jezoensis var. hondoensis. A. mariesii and T. diversifolia may survive in shade conditions by a lower MRNP(LM) than the two other species. Therefore, species differences in aboveground and belowground architecture and MRNPLM reflected their shade tolerance and regeneration strategies, which contribute to their coexistence.

  1. Determination of the molecular signature of fossil conifers by experimental palaeochemotaxonomy - Part 1: The Araucariaceae family

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Hautevelle, Y.; Michels, R.

    2012-08-01

    Several extant species of the Araucariaceae family (one of the families of conifers) were invested for the experimental artificial maturation by confined pyrolysis, in order to realize the transformation of biomolecules to geomolecules in laboratory conditions. The experimental study of diagenetized molecular signatures of the Araucariaceae species (common, inter- and infra-generic characteristics) allow to complete our knowledge in botanical palaeochemotaxonomy. Such knowledge is relevant to the reconstitution of palaeoflora and palaeoclimatic reconstruction, archaeology and environmental studies. In this work, major carbon skeleton types of Araucariaceae are detected in the organic solvent extracts of fresh and pyrolyzed plants using gas chromatography-mass spectrometry. The results show that all species of Araucariaceae are firstly characterized by a predominance of saturated tetracyclic diterpenoids. Moreover, the Araucaria genus shows a high relative abundance of bicyclic sesquiterpenoids, particularly compounds of the cadalane-type compounds accompanied by those of eudesmane-type, bisabolane-type as well as chamazulene, pentamethyl-dihydroindenes. Diterpenoids are of the labdane-type, isopimarane, abietane-type (essentially derived from abietanoic acids) as well as isohexyl alkylaromatic hydrocarbons. Compared to the tetracyclic diterpenoids, these compounds show a relatively lower abundance, reaching trace levels in the case of saturated abietanes. Distribution of sesqui- and diterpenoids of Agathis shows some similarities to that of Araucaria, with the exception of one species, in which the tetracyclic compounds are absent and the abietane-type (essentially derived from abietanoic acids) predominant. High similarities between the Wollemia and Araucaria genera are observed. Both are characterized by some high relative abundance of tetracyclic compounds with no predominance of other specific diterpenoids.

  2. A test of the hydraulic vulnerability segmentation hypothesis in angiosperm and conifer tree species.

    PubMed

    Johnson, Daniel M; Wortemann, Remi; McCulloh, Katherine A; Jordan-Meille, Lionel; Ward, Eric; Warren, Jeffrey M; Palmroth, Sari; Domec, Jean-Christophe

    2016-08-01

    Water transport from soils to the atmosphere is critical for plant growth and survival. However, we have a limited understanding about many portions of the whole-tree hydraulic pathway, because the vast majority of published information is on terminal branches. Our understanding of mature tree trunk hydraulic physiology, in particular, is limited. The hydraulic vulnerability segmentation hypothesis (HVSH) stipulates that distal portions of the plant (leaves, branches and roots) should be more vulnerable to embolism than trunks, which are nonredundant organs that require a massive carbon investment. In the current study, we compared vulnerability to loss of hydraulic function, leaf and xylem water potentials and the resulting hydraulic safety margins (in relation to the water potential causing 50% loss of hydraulic conductivity) in leaves, branches, trunks and roots of four angiosperms and four conifer tree species. Across all species, our results supported strongly the HVSH as leaves and roots were less resistant to embolism than branches or trunks. However, branches were consistently more resistant to embolism than any other portion of the plant, including trunks. Also, calculated whole-tree vulnerability to hydraulic dysfunction was much greater than vulnerability in branches. This was due to hydraulic dysfunction in roots and leaves at less negative water potentials than those causing branch or trunk dysfunction. Leaves and roots had narrow or negative hydraulic safety margins, but trunks and branches maintained positive safety margins. By using branch-based hydraulic information as a proxy for entire plants, much research has potentially overestimated embolism resistance, and possibly drought tolerance, for many species. This study highlights the necessity to reconsider past conclusions made about plant resistance to drought based on branch xylem only. This study also highlights the necessity for more research of whole-plant hydraulic physiology to better

  3. Litter dynamics in two Sierran mixed conifer forests. I. Litterfall and decomposition rates

    USGS Publications Warehouse

    Stohlgren, Thomas J.

    1988-01-01

    Litterfall was measured for 4 years and leaf litter decomposition rates were studied for 3.6 years in two mixed conifer forest (giant sequoia-fir and fir-pine) in the southern Sierra Nevada of California. The giant sequoia-fir forest (GS site) was dominated by giant sequoia (Sequoiadendron giganteum (Lindl.) Buchh.), white fir (Abies concolor Lindl. & Gord.), and sugar pine (Pinus lambertiana Dougl.). The fir-pine forest (FP site) was dominated by white fir, sugar pine, and incense cedar (Calocedrus decurrens (Torr.) Florin). Litterfall, including large woody debris -1•year-1 compared with 4355 kg•ha-1•year-1 at the FP site (3.4:1). In the GS site, leaf litter decomposition after 3.6 years was slowest for giant sequoia (28.2% mass loss), followed by sugar pine (34.3%) and white fie (45.1%). In the FP site, mass loss was slowest for sugar pine (40.0%), followed by white fir (45.1%), while incense cedar showed the greatest mass loss (56.9%) after 3.6 years. High litterfall rates of large woody debris (i.e., 2.5-15.2 cm diameter) and slow rates of leaf litter decomposition in the giant sequoia-fir forest type may result in higher litter accumulation rates than in the fir-pine type. Leaf litter times to 95% decay for the GS and FP sites were 30 and 27 years, respectively, if the initial 0.7-year period (a short period of rapid mass decay) was ignored in the calculation. A mass balance approach for total litterfall (<15.2 cm diameter) decomposition yielded lower decay constants than did the litterbag study and therefore longer times to 95% decay (57 years for the GS site and 62 years for the FP site).

  4. Litter dynamics in two Sierran mixed conifer forests. II. Nutrient release in decomposing leaf litter

    USGS Publications Warehouse

    Stohlgren, Thomas J.

    1988-01-01

    The factors influencing leaf litter decomposition and nutrient release patterns were investigated for 3.6 years in two mixed conifer forests in the southern Sierra Nevada of California. The giant sequoia–fir forest was dominated by giant sequoia (Sequoiadendrongiganteum (Lindl.) Buchh.), white fir (Abiesconcolor Lindl. & Gord.), and sugar pine (Pinuslambertiana Dougl.). The fir–pine forest was dominated by white fir, sugar pine, and incense cedar (Calocedrusdecurrens (Torr.) Florin). Initial concentrations of nutrients and percent lignin, cellulose, and acid detergent fiber vary considerably in freshly abscised leaf litter of the studied species. Giant sequoia had the highest concentration of lignin (20.3%) and the lowest concentration of nitrogen (0.52%), while incense cedar had the lowest concentration of lignin (9.6%) and second lowest concentration of nitrogen (0.63%). Long-term (3.6 years) foliage decomposition rates were best correlated with initial lignin/N (r2 = 0.94, p r2 = 0.92, p r2 = 0.80, p < 0.05). Patterns of nutrient release were highly variable. Giant sequoia immobilized N and P, incense cedar immobilized N and to a lesser extent P, while sugar pine immobilized Ca. Strong linear or negative exponential relationships existed between initial concentrations of N, P, K, and Ca and percent original mass remaining of those nutrients after 3.6 years. This suggests efficient retention of these nutrients in the litter layer of these ecosystems. Nitrogen concentrations steadily increase in decomposing leaf litter, effectively reducing the C/N ratios from an initial range of 68–96 to 27–45 after 3.6 years.

  5. Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest.

    PubMed

    Dore, Sabina; Fry, Danny L; Collins, Brandon M; Vargas, Rodrigo; York, Robert A; Stephens, Scott L

    2016-01-01

    Forest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60-70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related

  6. Carbon balance of conifer seedlings at timberline: relative changes in uptake, storage, and utilization.

    PubMed

    Bansal, S; Germino, M J

    2008-11-01

    Low rates of growth for conifers at high elevations may relate to problems in acquiring or utilizing carbon. A traditional hypothesis for growth limits of trees at alpine treeline is that low photosynthesis (A) leads to insufficient supply of carbon for growth. Alternatively, the sink-limitation hypothesis questions the importance of low A, and suggests that trees at treeline have abundant carbon for growth as a result of greater decreases in carbon use [respiration (R) and growth] than A at higher elevations. Concentrations of carbon intermediates (e.g., nonstructural carbohydrates, NSC) have been used to support the sink-limitation hypothesis, with the assumption that NSC reflects the ratio of carbon source to sinks. Our objective was to determine elevation effects on carbon balance (whole-plant uptake, storage, and efflux of carbon) of tree seedlings during their critical establishment phase at timberline. Changes in A and R (of whole crowns), NSC (starches and simple sugars), and growth were measured in seedlings of a treeline (Abies lasiocarpa) and nontreeline species (Pseudotsuga menziesii). Seedlings were outplanted at the lower (2,450 m) and upper (3,000 m) edges of the timberline zone in the Rocky Mountains, USA. At the upper compared with lower elevation, both species had 10-20% less root and needle growth, 13-15% less A, 35-39% less R, and up to 50% greater NSC. A. lasiocarpa allocated more biomass to needles and had greater A but less NSC than P. menziesii. The greater effects of elevation on R compared with A led to a 1.3-fold increase in A:R at the upper elevation, and a corresponding increase in starch (r2 = 0.42)-a pattern consistent with the predictions of the sink-limitation hypothesis. Nevertheless, A and dry mass gain were positively correlated (r2 = 0.42), indicating that variation in photosynthesis was related to growth of seedlings at timberline. PMID:18810499

  7. A test of the hydraulic vulnerability segmentation hypothesis in angiosperm and conifer tree species.

    PubMed

    Johnson, Daniel M; Wortemann, Remi; McCulloh, Katherine A; Jordan-Meille, Lionel; Ward, Eric; Warren, Jeffrey M; Palmroth, Sari; Domec, Jean-Christophe

    2016-08-01

    Water transport from soils to the atmosphere is critical for plant growth and survival. However, we have a limited understanding about many portions of the whole-tree hydraulic pathway, because the vast majority of published information is on terminal branches. Our understanding of mature tree trunk hydraulic physiology, in particular, is limited. The hydraulic vulnerability segmentation hypothesis (HVSH) stipulates that distal portions of the plant (leaves, branches and roots) should be more vulnerable to embolism than trunks, which are nonredundant organs that require a massive carbon investment. In the current study, we compared vulnerability to loss of hydraulic function, leaf and xylem water potentials and the resulting hydraulic safety margins (in relation to the water potential causing 50% loss of hydraulic conductivity) in leaves, branches, trunks and roots of four angiosperms and four conifer tree species. Across all species, our results supported strongly the HVSH as leaves and roots were less resistant to embolism than branches or trunks. However, branches were consistently more resistant to embolism than any other portion of the plant, including trunks. Also, calculated whole-tree vulnerability to hydraulic dysfunction was much greater than vulnerability in branches. This was due to hydraulic dysfunction in roots and leaves at less negative water potentials than those causing branch or trunk dysfunction. Leaves and roots had narrow or negative hydraulic safety margins, but trunks and branches maintained positive safety margins. By using branch-based hydraulic information as a proxy for entire plants, much research has potentially overestimated embolism resistance, and possibly drought tolerance, for many species. This study highlights the necessity to reconsider past conclusions made about plant resistance to drought based on branch xylem only. This study also highlights the necessity for more research of whole-plant hydraulic physiology to better

  8. Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest

    PubMed Central

    Dore, Sabina; Fry, Danny L.; Collins, Brandon M.; Vargas, Rodrigo; York, Robert A.; Stephens, Scott L.

    2016-01-01

    Forest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60–70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related

  9. Increased selfing and correlated paternity in a small population of a predominantly outcrossing conifer, Pinus sylvestris.

    PubMed

    Robledo-Arnuncio, J J; Alía, R; Gil, L

    2004-09-01

    Outcrossing rate, the rates of ovule and seed abortion, and levels of correlated paternity were estimated in a small population of Pinus sylvestris, a predominantly outcrossing conifer, and were compared with estimates from two widely dispersed woodlands of the same species, showing a range of densities. On average, seed trees of the small population showed an eight-fold higher selfing rate (25 vs. 3%) and a 100-fold greater incidence of correlated paternity (19.6 vs. 0.2%) than did trees from the large populations. No evidence was found of pollen limitation within the remnant stand, as suggested by ovule abortion rates. Investigation of the mating patterns in the small population, based on the unambiguous genealogy of 778 open-pollinated seeds, showed a large departure from random mating. Only 8% of the possible mating pairs within the stand were observed. Correlated paternity rate within a maternal sibship was negatively associated (rs = -0.398, P < 0.050) with the distance to the nearest neighbour, and shared paternity among maternal sibships was negatively correlated (rs = -0.704, P < 0.001) with the distance between seed trees. Numerical simulations, based on the estimated individual pollen dispersal kernel, suggest that restricted dispersal might have been the key factor affecting mating patterns in the small population and, together with low population density, may account for the observed mating system variation between the small and the large populations. The results of this study show that a severe size reduction may substantially affect the mating system of a wind-pollinated, typically outcrossed plant species.

  10. A test of the hydraulic vulnerability segmentation hypothesis in angiosperm and conifer tree species

    DOE PAGES

    Johnson, Daniel M.; Wortemann, Remi; McCulloh, Katherine A.; Jordan-Meille, Lionel; Ward, Eric; Warren, Jeffrey M.; Palmroth, Sari; Domec, Jean -Christophe

    2016-05-04

    Water transport from soils to the atmosphere is critical for plant growth and survival. However, we have a limited understanding about many portions of the whole-tree hydraulic pathway, because the vast majority of published information is on terminal branches. Our understanding of mature tree trunk hydraulic physiology, in particular, is limited. The hydraulic vulnerability segmentation hypothesis (HVSH) stipulates that distal portions of the plant (leaves, branches and roots) should be more vulnerable to embolism than trunks, which are non-redundant organs that require a massive carbon investment. In the current study, we compared vulnerability to loss of hydraulic function, leaf andmore » xylem water potentials and the resulting hydraulic safety margins (in relation to the water potential causing 50% loss of hydraulic conductivity) in leaves, branches, trunks and roots of four angiosperms and four conifer tree species. Across all species, our results supported strongly the HVSH as leaves and roots were less resistant to embolism than branches or trunks. However, branches were consistently more resistant to embolism than any other portion of the plant, including trunks. Also, calculated whole-tree vulnerability to hydraulic dysfunction was much greater than vulnerability in branches. This was due to hydraulic dysfunction in roots and leaves at less negative water potentials than those causing branch or trunk dysfunction. Leaves and roots had narrow or negative hydraulic safety margins, but trunks and branches maintained positive safety margins. By using branch-based hydraulic information as a proxy for entire plants, much research has potentially overestimated embolism resistance, and possibly drought tolerance, for many species. This study highlights the necessity to reconsider past conclusions made about plant resistance to drought based on branch xylem only. As a result, this study also highlights the necessity for more research of whole-plant hydraulic

  11. Linking microbial comunity composition and soil processes in acalifornia annual grassland and mixed-conifer forest

    SciTech Connect

    Balser, T.C.; Firestone, M.K.

    2003-07-21

    To investigate the potential role of microbial community composition in soil carbon and nitrogen cycling, we transplanted soil cores between a grassland and a conifer ecosystem in the Sierra Nevada California and measured soil process rates (N-mineralization, nitrous oxide and carbon dioxide flux, nitrification potential), soil water and temperature, and microbial community parameters (PLFA and substrate utilization profiles) over a 2 year period. Our goal was to assess whether microbial community composition could be related to soil process rates independent of soil temperature and water content. We performed multiple regression analyses using microbial community parameters and soil water and temperature as X-variables and soil process rates and inorganic N concentrations as Y-variables. We found that field soil temperature had the strongest relationship with CO2 production and soil NH4+ concentration, while microbial community characteristics correlated with N2O production, nitrification potential, gross N-mineralization, and soil NO3 concentration, independent of environmental controllers. We observed a relationship between specific components of the microbial community (as determined by PLFA) and soil processes, particularly processes tightly linked to microbial phylogeny (e.g. nitrification). The most apparent change in microbial community composition in response to the 2 year transplant was a change in relative abundance of fungi (there was only one significant change in PLFA biomarkers for bacteria during 2years). The relationship between microbial community composition and soil processes suggests that prediction of ecosystem response to environmental change may be improved by recognizing and accounting for changes in microbial community composition and physiological ecology.

  12. DNA Barcode Identification of Podocarpaceae—The Second Largest Conifer Family

    PubMed Central

    Little, Damon P.; Knopf, Patrick; Schulz, Christian

    2013-01-01

    We have generated matK, rbcL, and nrITS2 DNA barcodes for 320 specimens representing all 18 extant genera of the conifer family Podocarpaceae. The sample includes 145 of the 198 recognized species. Comparative analyses of sequence quality and species discrimination were conducted on the 159 individuals from which all three markers were recovered (representing 15 genera and 97 species). The vast majority of sequences were of high quality (B30 = 0.596–0.989). Even the lowest quality sequences exceeded the minimum requirements of the BARCODE data standard. In the few instances that low quality sequences were generated, the responsible mechanism could not be discerned. There were no statistically significant differences in the discriminatory power of markers or marker combinations (p = 0.05). The discriminatory power of the barcode markers individually and in combination is low (56.7% of species at maximum). In some instances, species discrimination failed in spite of ostensibly useful variation being present (genotypes were shared among species), but in many cases there was simply an absence of sequence variation. Barcode gaps (maximum intraspecific p–distance > minimum interspecific p–distance) were observed in 50.5% of species when all three markers were considered simultaneously. The presence of a barcode gap was not predictive of discrimination success (p = 0.02) and there was no statistically significant difference in the frequency of barcode gaps among markers (p = 0.05). In addition, there was no correlation between number of individuals sampled per species and the presence of a barcode gap (p = 0.27). PMID:24312258

  13. Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest.

    PubMed

    Dore, Sabina; Fry, Danny L; Collins, Brandon M; Vargas, Rodrigo; York, Robert A; Stephens, Scott L

    2016-01-01

    Forest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60-70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related

  14. Foliar phosphite application has minor phytotoxic impacts across a diverse range of conifers and woody angiosperms.

    PubMed

    Scott, Peter; Bader, Martin Karl-Friedrich; Williams, Nari Michelle

    2016-10-01

    Phytophthora plant pathogens cause tremendous damage in planted and natural systems worldwide. Phosphite is one of the only effective chemicals to control broad-scale Phytophthora disease. Little work has been done on the phytotoxic effects of phosphite application on plant communities especially in combination with plant physiological impacts. Here, we tested the phytotoxic impact of phosphite applied as foliar spray at 0, 12, 24 and 48 kg a.i. ha(-1) . Eighteen-month-old saplings of 13 conifer and angiosperm species native to New Zealand, and two exotic coniferous species were treated and the development of necrotic tissue and chlorophyll-a-fluorescence parameters (optimal quantum yield, Fv /Fm ; effective quantum yield of photosystem II, ΦPSII ) were assessed. In addition, stomatal conductance (gs ) was measured on a subset of six species. Significant necrosis assessed by digital image analysis occurred in only three species: in the lauraceous canopy tree Beilschmiedia tawa (8-14%) and the understory shrub Dodonaea viscosa (5-7%) across phosphite concentrations and solely at the highest concentration in the myrtaceous pioneer shrub Leptospermum scoparium (66%). In non-necrotic tissue, Fv /Fm , ΦPSII and gs remained unaffected by the phosphite treatment. Overall, our findings suggest minor phytotoxic effects resulting from foliar phosphite application across diverse taxa and regardless of concentration. This study supports the large-scale use of phosphite as a management tool to control plant diseases caused by Phytophthora pathogens in plantations and natural ecosystems. Long-term studies are required to ascertain potential ecological impacts of repeated phosphite applications. PMID:26968132

  15. Interactive control of minerals, wildfire, and erosion on soil carbon stabilization in conifer ecosystems of the western U.S.

    NASA Astrophysics Data System (ADS)

    Rasmussen, C.

    2014-12-01

    Answering the question of what controls the fate and stabilization of organic carbon in forest soils is central to understanding the role of western US ecosystems in mitigating climate change, optimizing forest management, and quantifying local and regional terrestrial carbon budgets. Over half of forest soil C is stored belowground, stabilized by a number of separate, but interacting physical, chemical and biological mechanisms. Here we synthesize data from a series of field and laboratory studies focused on identifying mineral, physical, and landscape position controls on belowground C stabilization mechanisms in western U.S. conifer ecosystems. Results from these studies demonstrate an important for role for short-range-order Fe- and Al-oxyhydroxides and Al-humus complexes in C stabilization, and that the soil mineral assemblage moderates C cycling via control on partitioning of C into physical fractions ("free", "occluded", "mineral") with varying MRT and chemistry. Measures of occluded fraction chemical composition by 13C-NMR indicate this fraction is 2-5 times more enriched in pyrogenic C than the bulk soil and that this fraction is on the order of ~25 to 65% charred materials. Radiocarbon analyses of a large set of conifer soil samples from California and Arizona further indicate the occluded fraction is generally older than either the free light or mineral fraction. In particular, soil C in convergent, water and sediment gathering portions of the landscape are enriched in long MRT charred materials. These results indicate an important role for the interaction of soil mineral assemblage, wildfire, and erosion in controlling belowground C storage and stabilization in western conifer forests. Drought and wildfire are expected to increase with climate change and thus may exert significant control on belowground C storage directly through biochemical and physical changes in aboveground biomass, production of charred materials, and indirectly via post

  16. A spruce gene map infers ancient plant genome reshuffling and subsequent slow evolution in the gymnosperm lineage leading to extant conifers

    PubMed Central

    2012-01-01

    Background Seed plants are composed of angiosperms and gymnosperms, which diverged from each other around 300 million years ago. While much light has been shed on the mechanisms and rate of genome evolution in flowering plants, such knowledge remains conspicuously meagre for the gymnosperms. Conifers are key representatives of gymnosperms and the sheer size of their genomes represents a significant challenge for characterization, sequencing and assembling. Results To gain insight into the macro-organisation and long-term evolution of the conifer genome, we developed a genetic map involving 1,801 spruce genes. We designed a statistical approach based on kernel density estimation to analyse gene density and identified seven gene-rich isochors. Groups of co-localizing genes were also found that were transcriptionally co-regulated, indicative of functional clusters. Phylogenetic analyses of 157 gene families for which at least two duplicates were mapped on the spruce genome indicated that ancient gene duplicates shared by angiosperms and gymnosperms outnumbered conifer-specific duplicates by a ratio of eight to one. Ancient duplicates were much more translocated within and among spruce chromosomes than conifer-specific duplicates, which were mostly organised in tandem arrays. Both high synteny and collinearity were also observed between the genomes of spruce and pine, two conifers that diverged more than 100 million years ago. Conclusions Taken together, these results indicate that much genomic evolution has occurred in the seed plant lineage before the split between gymnosperms and angiosperms, and that the pace of evolution of the genome macro-structure has been much slower in the gymnosperm lineage leading to extent conifers than that seen for the same period of time in flowering plants. This trend is largely congruent with the contrasted rates of diversification and morphological evolution observed between these two groups of seed plants. PMID:23102090

  17. Natural 'background' soil water repellency in conifer forests: its prediction and relationship to wildfire occurrence

    NASA Astrophysics Data System (ADS)

    Doerr, Stefan; Woods, Scott; Martin, Deborah; Casimiro, Marta

    2013-04-01

    Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by col- lecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were fur- ther analyzed for repellency using WDPT and contact angle (hsl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelma- nii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long- unburnt conifer forest soils of the north-western USA is

  18. Changes to the N cycle following bark beetle outbreaks in two contrasting conifer forest types.

    PubMed

    Griffin, Jacob M; Turner, Monica G

    2012-10-01

    Outbreaks of Dendroctonus beetles are causing extensive mortality in conifer forests throughout North America. However, nitrogen (N) cycling impacts among forest types are not well known. We quantified beetle-induced changes in forest structure, soil temperature, and N cycling in Douglas-fir (Pseudotsuga menziesii) forests of Greater Yellowstone (WY, USA), and compared them to published lodgepole pine (Pinus contorta var. latifolia) data. Five undisturbed stands were compared to five beetle-killed stands (4-5 years post-outbreak). We hypothesized greater N cycling responses in Douglas-fir due to higher overall N stocks. Undisturbed Douglas-fir stands had greater litter N pools, soil N, and net N mineralization than lodgepole pine. Several responses to disturbance were similar between forest types, including a pulse of N-enriched litter, doubling of soil N availability, 30-50 % increase in understory cover, and 20 % increase in foliar N concentration of unattacked trees. However, the response of some ecosystem properties notably varied by host forest type. Soil temperature was unaffected in Douglas-fir, but lowered in lodgepole pine. Fresh foliar %N was uncorrelated with net N mineralization in Douglas-fir, but positively correlated in lodgepole pine. Though soil ammonium and nitrate, net N mineralization, and net nitrification all doubled, they remained low in both forest types (<6 μg N g soil(-1) NH(4) (+)or NO(3) (-); <25 μg N g soil(-1) year(-1) net N mineralization; <8 μg N g soil(-1) year(-1) net nitrification). Results suggest that beetle disturbance affected litter and soil N cycling similarly in each forest type, despite substantial differences in pre-disturbance biogeochemistry. In contrast, soil temperature and soil N-foliar N linkages differed between host forest types. This result suggests that disturbance type may be a better predictor of litter and soil N responses than forest type due to similar disturbance mechanisms and disturbance legacies

  19. Atmospheric deposition and solute export in giant sequoia: mixed conifer watersheds in the Sierra Nevada, California

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Melack, John M.; Esperanza, Anne M.; Parsons, David J.

    1991-01-01

    Atmospheric depostion and stream discharge and solutes were measured for three years (September 1984 - August 1987) in two mixed conifer watersheds in Sequoia National Park, in the southern Sierra Nevada of California. The Log Creek watershed (50 ha, 2067-2397 m elev.) is drained by a perennial stream, while Tharp's Creek watershed (13 ha, 2067-2255 m elev.) contains an intermittent stream. Dominant trees in the area include Abies concolor (white fir), Sequoiadendron giganteum (giant sequoia), A. magnifica (red fir), and Pinus lambertiana (sugar pine). Bedrock is predominantly granite and granodiorite, and the soils are mostly Pachic Xerumbrepts. Over the three year period, sulfate (SO42-), nitrate (NO3-), and chloride (Cl-) were the major anions in bulk precipitation with volume-weighted average concentrations of 12.6, 12.3 and 10.0 μeq/1, respectively. Annual inputs of NO3-N, NH4-N and SO4-S from wet deposition were about 60 to 75% of those reported from bulk deposition collectors. Discharge from the two watersheds occurs primarily during spring snowmelt. Solute exports from Log and Tharp's Creeks were dominated by HCO3-, Ca2+ and Na+, while H+, NO3-, NH4+ and PO43- outputs were relatively small. Solute concentrations were weakly correlated with instantaneous stream flow for all solutes (r2 3- (Log Cr. r2=0.72; Tharp's Cr. r2=0.38), Na+ (Log Cr. r2=0.56; Tharp's Cr. r2=0.47), and silicate (Log Cr. r2=0.71; Tharp's Cr. r2=0.49). Mean annual atmospheric contributions of NO3-N (1.6 kg ha-1), NH4-N (1.7 kg ha-1), and SO4-S (1.8 kg ha-1), which are associated with acidic deposition, greatly exceed hydrologic losses. Annual watershed yields (expressed as eq ha-1) of HCO3- exceeded by factors of 2.5 to 37 the annual atmospheric deposition of H+.

  20. Towards scaling interannual ecohydrological responses of conifer forests to bark beetle infestations from individuals to landscapes

    NASA Astrophysics Data System (ADS)

    Mackay, D. S.; Ewers, B. E.; Peckham, S. D.; Savoy, P.; Reed, D. E.; Frank, J. M.

    2013-12-01

    Widespread epidemics of forest-damaging insects have severe implications for the interconnections between water and ecosystem processes under present-day climate. How these systems respond to future climates is highly uncertain, and so there is a need for a better understanding of the effects of such disturbances on plant hydraulics, and the consequent effects on ecosystem processes. Moreover, large-scale manifestations of such disturbances require scaling knowledge obtained from individual trees or stands up to a regional extent. This requires a conceptual framework that integrates physical and biological processes that are immutable and scalable. Indeed, in Western North America multiple conifer species have been impacted by the bark beetle epidemic, but the prediction of such widespread outbreaks under changing environmental conditions must be generalized from a relatively small number of ground-based observations. Using model-data fusion we examine the fundamental principles that drive ecological and hydrological responses to bark beetles infestation from individuals to regions. The study includes a mid-elevation (2750 m a.s.l) lodgepole pine forest and higher (3190 m a.s.l.) elevation Engelmann spruce - fir forest in southern Wyoming. The study included a suite of observations, comprising leaf gas exchange, non-structural carbon (NSC), plant hydraulics, including sap flux transpiration (E), vulnerability to cavitation, leaf water potentials, and eddy covariance, were made pre-, during-, and post-disturbance, as the bark beetle infestation moved through these areas. Numerous observations tested hypotheses generated by the Terrestrial Regional Ecosystem Exchange Simulator (TREES), which integrates soil hydraulics and dynamic tree hydraulics (cavitation) with canopy energy and gas exchange, and operates at scales from individuals to landscapes. TREES accurately predicted E and NSC dynamics among individuals spanning pre- and post-disturbance periods, with the 95

  1. Ecological importance of large-diameter trees in a temperate mixed-conifer forest.

    PubMed

    Lutz, James A; Larson, Andrew J; Swanson, Mark E; Freund, James A

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m(2). We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by

  2. Investigating the impacts of recycled water on long-lived conifers

    PubMed Central

    Nackley, Lloyd L.; Barnes, Corey; Oki, Lorence R.

    2015-01-01

    maintaining healthy verdant landscapes that include coast redwoods and other long-lived conifers. PMID:25876628

  3. Patch to landscape patterns in post fire recruitment of a serotinous conifer

    USGS Publications Warehouse

    Ne'eman, G.; Fotheringham, C.J.; Keeley, J.E.

    1999-01-01

    Obligate seeding species are highly specialized to fire disturbance and many conifers such as cypress, which are adapted to high intensity stand-replacing fires, have canopy seed banks stored in serotinous cones. Resilience of these trees to fire disturbance is a function of disturbance frequency and one focus of this study was to determine the effect of patch age on postfire recruitment. A second focus was to determine the extent to which fire induced a landscape level change in the location of the forest boundary. Prior to a fire in 1994, a large Cupressus sargentii forest was a mosaic landscape of different aged patches of nearly pure cypress bordered by chaparral. Patches less than 60 years of age were relatively dense with roughly one tree every 1-2 m2 but older patches had thinned to one tree every 3-15 m2. Older trees had substantially greater canopy cone crops but the stand level seed bank size was not significantly correlated with stand age. Fire-dependent obligate seeding species are sensitive to fire return interval because of potential changes in the size of seed banks - facing both a potential 'immaturity risk' and a 'senescence risk'. At our site, C. sargentii regeneration was substantial in stands as young as 20 years, suggesting that fire return interval would need to be shorter than this to pose any significant risk. Reduced seedling recruitment in stands nearly 100 years of age may indicate risk from senescence is greater, however, even the lowest density seedling recruitment was many times greater than the density of mature forests - thus this cypress would appear to be resilient to a wide range of fire return intervals. Changes in landscape patterning of forest and chaparral are unlikely except after fire. Factors that inhibit tree establishment within the shrubland, as well as factors that affect shrub establishment within the forest border likely affect the 'permeability' of this ecotone. After the 1994 fire this boundary appeared to be stable

  4. Ecological Importance of Large-Diameter Trees in a Temperate Mixed-Conifer Forest

    PubMed Central

    Lutz, James A.; Larson, Andrew J.; Swanson, Mark E.; Freund, James A.

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m2. We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by a

  5. Comparing growth phenology of co-occurring deciduous and evergreen conifers exposed to drought

    PubMed Central

    Swidrak, Irene; Schuster, Roman; Oberhuber, Walter

    2013-01-01

    indicate sink competition for carbohydrates to belowground organs. This is supported by completion of apical growth in mid June in all species, except for needle growth of Pinus sylvestris, which lasted until early August. Phenological observations of conifers exposed to drought revealed that tree water status early during the growing season determines total annual aboveground growth and besides temperature, species-specific endogenous and/or environmental factors (most likely photoperiod and/or different threshold temperatures) are involved in controlling apical and lateral growth resumption after winter dormancy. PMID:24273375

  6. New datasets for quantifying snow-vegetation-atmosphere interactions in boreal birch and conifer forests

    NASA Astrophysics Data System (ADS)

    Reid, T. D.; Essery, R.; Rutter, N.; Huntley, B.; Baxter, R.; Holden, R.; King, M.; Hancock, S.; Carle, J.

    2012-12-01

    Boreal forests exert a strong influence on weather and climate by modifying the surface energy and radiation balance. However, global climate and numerical weather prediction models use forest parameter values from simple look-up tables or maps that are derived from limited satellite data, on large grid scales. In reality, Arctic landscapes are inherently heterogeneous, with highly variable land cover types and structures on a variety of spatial scales. There is value in collecting detailed field data for different areas of vegetation cover, to assess the accuracy of large-scale assumptions. To address these issues, a consortium of researchers funded by the UK's Natural Environment Research Council have collected extensive data on radiation, meteorology, snow cover and canopy structure at two contrasting Arctic forest sites. The chosen study sites were an area of boreal birch forest near Abisko, Sweden in March/April 2011 and mixed conifer forest at Sodankylä, Finland in March/April 2012. At both sites, arrays comprising ten shortwave pyranometers and four longwave pyrgeometers were deployed for periods of up to 50 days, under forest plots of varying canopy structures and densities. In addition, downwelling longwave irradiance and global and diffuse shortwave irradiances were recorded at nearby open sites representing the top-of-canopy conditions. Meteorological data were recorded at all sub-canopy and open sites using automatic weather stations. Over the same periods, tree skin temperatures were measured on selected trees using contact thermocouples, infrared thermocouples and thermal imagery. Canopy structure was accurately quantified through manual surveys, extensive hemispherical photography and terrestrial laser scans of every study plot. Sub-canopy snow depth and snow water equivalent were measured on fine-scale grids at each study plot. Regular site maintenance ensured a high quality dataset covering the important Arctic spring period. The data have several

  7. Stem demography and post-fire recruitment of a resprouting serotinous conifer

    USGS Publications Warehouse

    Keeley, J.E.; Keeley, M.B.; Bond, W.J.

    1999-01-01

    The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4 - 9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionally Widdringtonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fries, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in the Cupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait

  8. Fuel deposition rates of montane and subalpine conifers in the central Sierra Nevada, California, USA

    USGS Publications Warehouse

    van Wagtendonk, J.W.; Moore, P.E.

    2010-01-01

    Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total of 176 sampling sites. We used these data to develop predictive equations for each fuel class and diameter size class of each species based on stem and crown characteristics. There were consistent species and diameter class differences in the annual amount of foliage and fragments deposited. Foliage deposition rates ranged from just over 50 g m-2 year-1 in small diameter mountain hemlock stands to ???300 g m-2 year-1 for the three largest diameter classes of giant sequoia. The deposition rate for most woody fuel classes increased from the smallest diameter class stands to the largest diameter class stands. Woody fuel deposition rates varied among species as well. The rates for the smallest woody fuels ranged from 0.8 g m-2 year-1 for small diameter stands of Jeffrey pine to 126.9 g m-2 year-1 for very large diameter stands of mountain hemlock. Crown height and live crown ratio were the best predictors of fuel deposition rates for most fuel classes and species. Both characteristics reflect the amount of crown biomass including foliage and woody fuels. Relationships established in this study allow predictions of fuel loads to be made on a stand basis for each of these species under current and possible future conditions. These predictions can be used to

  9. CO2-induced decrease of canopy stomatal conductance of mature conifer and broadleaved trees

    NASA Astrophysics Data System (ADS)

    Tor-ngern, P.; Oren, R.; Ward, E. J.; Palmroth, S.; McCarthy, H. R.; domec, J.

    2013-12-01

    Together with canopy leaf area, mean canopy stomatal conductance (GS) controls forest-atmosphere exchanges of energy and mass. Expectations for stomatal response to elevated atmospheric [CO2] (CO2E) based on seedling studies range from large decreases of conductance in foliage of broadleaved species to little or no response in conifers. These responses are not directly translatable to forest canopies, and their underlying mechanisms are ill-defined. The uncertainty of canopy-scale stomatal response to CO2E reduces confidence in modeled predictions of future forest productivity and carbon sequestration, and of partitioning of net radiation between latent and sensible heat flux. Thus, debates on the potential effects of CO2E-induced stomatal closure continue. We used a Free-Air CO2 Enrichment (FACE) experiment in a 27-year-old, 25 m tall forest, to generate a whole-canopy CO2-response and test whether canopy-scale GS response to CO2E of widely distributed, fast growing shade-intolerant species, Pinus taeda (L.) and co-occurring broadleaved species dominated by Liquidambar styraciflua (L.), was indirectly affected by slow changes such as hydraulic adjustments and canopy development, as opposed to quickly responding to CO2 concentrations in the leaf-internal air space. Our results show indirect CO2E-induced reductions of GS of 10% and 30%, respectively, and no signs of a direct stomatal response even as CO2E was pushed to 685 μmol mol-1 (~1.8 of ambient). Modeling the effect of CO2E on the water, energy and carbon cycles of forests must consider slow-response indirect mechanisms producing large variation in the reduction of GS, such as the previously observed inconsistent CO2E effect on canopy leaf area and plant hydraulics. Moreover, the new generation of CO2E studies in forests must allow indirect effects caused by, e.g., hydraulic adjustments and canopy development, to play out. Such acclimation will be particularly prolonged in slowly developing ecosystems, such

  10. Factors driving mortality and growth at treeline: a 30-year experiment of 92 000 conifers.

    PubMed

    Barbeito, Ignacio; Dawes, Melissa A; Rixen, Christian; Senn, Josef; Bebi, Peter

    2012-02-01

    Understanding the interplay between environmental factors contributing to treeline formation and how these factors influence different life stages remains a major research challenge. We used an afforestation experiment including 92 000 trees to investigate the spatial and temporal dynamics of tree mortality and growth at treeline in the Swiss Alps. Seedlings of three high-elevation conifer species (Larix decidua, Pinus mugo ssp. uncinata, and Pinus cembra) were systematically planted along an altitudinal gradient at and above the current treeline (2075 to 2230 m above sea level [a.s.l.]) in 1975 and closely monitored during the following 30 years. We used decision-tree models and generalized additive models to identify patterns in mortality and growth along gradients in elevation, snow duration, wind speed, and solar radiation, and to quantify interactions between the different variables. For all three species, snowmelt date was always the most important environmental factor influencing mortality, and elevation was always the most important factor for growth over the entire period studied. Individuals of all species survived at the highest point of the afforestation for more than 30 years, although mortality was greater above 2160 m a.s.l., 50-100 m above the current treeline. Optimal conditions for height growth differed from those for survival in all three species: early snowmelt (ca. day of year 125-140 [where day 1 is 1 January]) yielded lowest mortality rates, but relatively later snowmelt (ca. day 145-150) yielded highest growth rates. Although snowmelt and elevation were important throughout all life stages of the trees, the importance of radiation decreased over time and that of wind speed increased. Our findings provide experimental evidence that tree survival and height growth require different environmental conditions and that even small changes in the duration of snow cover, in addition to changes in temperature, can strongly impact tree survival and

  11. Ecological importance of large-diameter trees in a temperate mixed-conifer forest.

    PubMed

    Lutz, James A; Larson, Andrew J; Swanson, Mark E; Freund, James A

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m(2). We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by

  12. Comparing growth phenology of co-occurring deciduous and evergreen conifers exposed to drought.

    PubMed

    Swidrak, Irene; Schuster, Roman; Oberhuber, Walter

    2013-12-01

    indicate sink competition for carbohydrates to belowground organs. This is supported by completion of apical growth in mid June in all species, except for needle growth of Pinus sylvestris, which lasted until early August. Phenological observations of conifers exposed to drought revealed that tree water status early during the growing season determines total annual aboveground growth and besides temperature, species-specific endogenous and/or environmental factors (most likely photoperiod and/or different threshold temperatures) are involved in controlling apical and lateral growth resumption after winter dormancy.

  13. Late Miocene lineage divergence and ecological differentiation of rare endemic Juniperus blancoi: clues for the diversification of North American conifers.

    PubMed

    Moreno-Letelier, Alejandra; Mastretta-Yanes, Alicia; Barraclough, Timothy G

    2014-07-01

    Western North America and Mexico contain a large number of conifer species. This diversity could be the product of orographic and climate changes of the late Tertiary and Quaternary. In this study, we focus on the evolutionary history of Juniperus blancoi, in order to determine the impact of climate change and environmental heterogeneity on population differentiation. We estimated the population structure, phylogenetic relationships and historical demography of J. blancoi populations using nuclear genes. We correlated genetic structure with ecological differentiation, divergence times and changes in population size. Populations of J. blancoi are differentiated into three lineages that correspond to low-, mid- and high-altitude populations. The three groups diversified in the late Miocene, early Pliocene, with only a few events of gene flow since then. Two lineages in the north exhibited a pattern of population growth during the Pleistocene that could be linked to climate changes. Populations of J. blancoi experienced significant ecological differentiation and early divergence events, which correspond to periods of global cooling and mountain uplift during the Miocene. This suggests that mountain ranges in tropical and subtropical latitudes play an important role in the speciation and persistence of conifer taxa in diversity hotspots, by providing diverse environmental conditions.

  14. An integrated geographic information system approach for modeling the suitability of conifer habitat in an alpine environment

    NASA Astrophysics Data System (ADS)

    McGregor, Stephen J.

    1998-01-01

    Alpine periglacial environments within the forest-alpine tundra ecotone (FATE) may be among the first to reflect changes in habitat characteristics as a consequence of climatic change. Previous FATE studies used Integrated Geographic Information System (IGIS) techniques to collect and model biophysical data but lacked the necessary detail to model the micro-scale patterns and compositions of habitat within alpine periglacial environments. This paper describes several promising data collection, integration, and cartographic modeling techniques used in an IGIS approach to model alpine periglacial environments in Glacier National Park (GNP), Montana, USA. High-resolution (I X I m) multi-spectral remote sensing data and differentially corrected Global Positioning System (DGPS) data were integrated with other biophysical data using a raster-based IGIS approach. Biophysical factors, hypothesized to influence the pattern and composition of the FATE and the alpine tundra ecosystem, were derived from the high-resolution remote sensing data, in-situ GPS data, high-resolution models of digital elevation, and other thematic data using image processing techniques and cartographic modeling. Suitability models of conifer habitat were created using indices generated from the IGIS database. This IGIS approach identified suitable conifer habitat within the FATE and permitted the modeling of micro-scale periglacial features and alpine tundra communities that are absent from traditional approaches of landscape-scale (30 X 30 m) modeling.

  15. Areas of Agreement and Disagreement Regarding Ponderosa Pine and Mixed Conifer Forest Fire Regimes: A Dialogue with Stevens et al.

    PubMed Central

    Odion, Dennis C.; Hanson, Chad T.; Baker, William L.; DellaSala, Dominick A.; Williams, Mark A.

    2016-01-01

    In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa) and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue) agree that high-severity fire was a component of these forests, but disagree that one of the several sources of evidence, stand age from a large number of forest inventory and analysis (FIA) plots across the western USA, support our findings that severe fire played more than a minor role ecologically in these forests. Here we highlight areas of agreement and disagreement about past fire, and analyze the methods Stevens et al. used to assess the FIA stand-age data. We found a major problem with a calculation they used to conclude that the FIA data were not useful for evaluating fire regimes. Their calculation, as well as a narrowing of the definition of high-severity fire from the one we used, leads to a large underestimate of conditions consistent with historical high-severity fire. The FIA stand age data do have limitations but they are consistent with other landscape-inference data sources in supporting a broader paradigm about historical variability of fire in ponderosa and mixed-conifer forests than had been traditionally recognized, as described in our previous PLOS paper. PMID:27195808

  16. A biophysical gradient analysis of climate for understanding conifer establishment in mountain ecosystems of the western U.S.

    NASA Astrophysics Data System (ADS)

    Littell, J. S.; Graumlich, L. J.

    2007-12-01

    Establishment of conifer trees at upper treeline is controlled by both physical and ecological phenomena. The physical limitations on tree establishment and growth as well as the ecological and edaphic factors moderating climate vary significantly across western mountain ranges, from the more maritime Cascades through the basin- and-range to the heavily continental central Rockies. In order to understand the factors limiting tree establishment and estimate rates of ecosystem change under future climate change, it is critical to understand the climatic factors limiting tree establishment. We use a multiscale approach to identify climatic patterns associated with upper treeline in nine mountain ranges: the north Cascades, central Cascades, Eagle Cap, Beaverhead, Teton, Beartooth, Wind River, Snowy, and Zirkel mountain ranges. We examined NCDC divisional, SNOTEL, snowcourse, and DAYMET seasonal averages/totals for temperature and precipitation variables to compare the climates at treeline sites identified for conifer establishment research. Divisional data from 1948-2004 indicate a strong geographical gradient in winter precipitation/PDO correlations, but according to SNOTEL data from all mountain ranges, these differences are much weaker in the more recent past. Snow water equivalent at all the sites near the PDO dipole evident in the 1948-2004 correlations appears negatively correlated with PDO. We present DAYMET, SNOTEL, and snowcourse normals for the mountain environments near the treeline sites and relate them to species composition and the nature of recent establishment.

  17. Calculation of theoretical and empirical nutrient N critical loads in the mixed conifer ecosystems of southern California.

    PubMed

    Breiner, Joan; Gimeno, Benjamin S; Fenn, Mark

    2007-01-01

    Edaphic, foliar, and hydrologic forest nutrient status indicators from 15 mixed conifer forest stands in the Sierra Nevada, San Gabriel Mountains, and San Bernardino National Forest were used to estimate empirical or theoretical critical loads (CL) for nitrogen (N) as a nutrient. Soil acidification response to N deposition was also evaluated. Robust empirical relationships were found relating N deposition to plant N uptake (N in foliage), N fertility (litter C/N ratio), and soil acidification. However, no consistent empirical CL were obtained when the thresholds for parameters indicative of N excess from other types of ecosystems were used. Similarly, the highest theoretical CL for nutrient N calculated using the simple mass balance steady state model (estimates ranging from 1.4-8.8 kg N/ha/year) was approximately two times lower than the empirical observations. Further research is needed to derive the thresholds for indicators associated with the impairment of these mixed conifer forests exposed to chronic N deposition within a Mediterranean climate. Further development or parameterization of models for the calculation of theoretical critical loads suitable for these ecosystems will also be an important aspect of future critical loads research. PMID:17450298

  18. Development of the mixed conifer forest in northern New Mexico and its relationship to Holocene environmental change

    USGS Publications Warehouse

    Anderson, R. Scott; Jass, R.B.; Toney, J.L.; Allen, C.D.; Cisneros-Dozal, L. M.; Hess, M.; Heikoop, Jeff; Fessenden, J.

    2008-01-01

    Chihuahuen??os Bog (2925??m) in the Jemez Mountains of northern New Mexico contains one of the few records of late-glacial and postglacial development of the mixed conifer forest in southwestern North America. The Chihuahuen??os Bog record extends to over 15,000??cal yr BP. An Artemisia steppe, then an open Picea woodland grew around a small pond until ca. 11,700??cal yr BP when Pinus ponderosa became established. C/N ratios, ??13C and ??15N values indicate both terrestrial and aquatic organic matter was incorporated into the sediment. Higher percentages of aquatic algae and elevated C/N ratios indicate higher lake levels at the opening of the Holocene, but a wetland developed subsequently as climate warmed. From ca. 8500 to 6400??cal yr BP the pond desiccated in what must have been the driest period of the Holocene there. C/N ratios declined to their lowest Holocene levels, indicating intense decomposition in the sediment. Wetter conditions returned after 6400??cal yr BP, with conversion of the site to a sedge bog as groundwater levels rose. Higher charcoal influx rates after 6400??cal yr BP probably result from greater biomass production rates. Only minor shifts in the overstory species occurred during the Holocene, suggesting that mixed conifer forest dominated throughout the record. ?? 2008 University of Washington.

  19. A 14,000 year vegetation history of a hypermaritime island on the outer Pacific coast of Canada based on fossil pollen, spores and conifer stomata

    NASA Astrophysics Data System (ADS)

    Lacourse, Terri; Delepine, J. Michelle; Hoffman, Elizabeth H.; Mathewes, Rolf W.

    2012-11-01

    Pollen and conifer stomata analyses of lake sediments from Hippa Island on the north coast of British Columbia were used to reconstruct the vegetation history of this small hypermaritime island. Between 14,000 and 13,230 cal yr BP, the island supported diverse herb-shrub communities dominated by Cyperaceae, Artemisia and Salix. Pinus contorta and Picea sitchensis stomata indicate that these conifers were present among the herb-shrub communities, likely as scattered individuals. Transition to open P. contorta woodland by 13,000 cal yr BP was followed by increases in Alnus viridis, Alnus rubra and P. sitchensis. After 12,000 cal yr BP, Pinus-dominated communities were replaced by dense P. sitchensis and Tsuga heterophylla forest with Lysichiton americanus and fern understory. Thuja plicata stomata indicate that this species was present by 8700 cal yr BP, but the pollen record suggests that its populations did not expand to dominate regional rainforests, along with Tsuga and Picea, until after 6600 cal yr BP. Conifer stomata indicate that species may be locally present for hundreds to thousands of years before pollen exceed thresholds routinely used to infer local species arrival. When combined, pollen and conifer stomata can provide a more accurate record of paleovegetation than either when used alone.

  20. Simulating stand-level water and carbon fluxes in beetle-attacked conifer forests in the Western U.S

    NASA Astrophysics Data System (ADS)

    Peckham, S. D.; Ewers, B. E.; Mackay, D. S.; Pendall, E. G.; Frank, J. M.; Massman, W. J.

    2013-12-01

    In recent decades, forest mortality due to bark beetle infestation in conifer forests of western North America has reached epidemic levels, which may have profound effects on both present and future water and carbon cycling. The responses of evaporation, transpiration, and net photosynthesis to changing climate and disturbance are a major concern as they control the carbon balance of forests and the hydrologic cycle in a region that relies on water from montane and subalpine forest systems. Tree mortality during bark beetle infestation in this region is due to hydraulic failure resulting from fungal infection spread by the beetles. We modified the terrestrial regional ecosystem exchange simulator (TREES) model to incorporate xylem-occlusion effects on hydraulic conductance to simulate beetle attack over the period 2005-2012 in a subalpine conifer forest at the Glacier Lakes Ecosystem Experiment Site (GLEES) and over 2008-2012 at a lodgepole pine dominated site in southeast Wyoming. Model simulations with and without beetle effects were compared to eddy-covariance and sap-flux data measured at the sites. The simulations were run at a 30-minute time step and covered the pre- to post-beetle infestation period. Simulated NEE at GLEES ranged from 200 to -625 g C m-2 yr-1, annual ET ranged from 250 to 800 mm yr-1 over the seven years and standard error in predicted half-hourly NEE was <3 μmol CO2 m-2 s-1 and <2e-05 mm s-1 for ET. The stand transitioned from a C sink to C source during the beetle attack and our modified model captured this dynamic, while simulations without the beetle effect did not (i.e. continued C sink). However, simulated NEE was underestimated compared to flux data later in the infestation period (2011) by over 100 g C m-2 yr-1. ET decreased during beetle attack in both the observed and simulated data, but the modified model underestimated ET in the later phase of attack (2010-2011). These results suggest that ET and NEE in these conifer forests may

  1. Drought responses of conifers in ecotone forests of northern Arizona: tree ring growth and leaf delta13C.

    PubMed

    Adams, Henry D; Kolb, Thomas E

    2004-07-01

    We sought to understand differences in tree response to meteorological drought among species and soil types at two ecotone forests in northern Arizona, the pinyon-juniper woodland/ponderosa pine ecotone, and the higher elevation, wetter, ponderosa pine/mixed conifer ecotone. We used two approaches that provide different information about drought response: the ratio of standardized radial growth in wet years to dry years (W:D) for the period between years 1950 and 2000 as a measure of growth response to drought, and delta13C in leaves formed in non-drought (2001) and drought (2002) years as a measure of change in water use efficiency (WUE) in response to drought. W:D and leaf delta13C response to drought for Pinus edulis and P. ponderosa did not differ for trees growing on coarse-texture soils derived from cinders compared with finer textured soils derived from flow basalts or sedimentary rocks. P. ponderosa growing near its low elevation range limit at the pinyon-juniper woodland/ponderosa pine ecotone had a greater growth response to drought (higher W:D) and a larger increase in WUE in response to drought than co-occurring P. edulis growing near its high elevation range limit. P. flexilis and Pseudotsuga menziesii growing near their low elevation range limit at the ponderosa pine/mixed conifer ecotone had a larger growth response to drought than co-occurring P. ponderosa growing near its high elevation range limit. Increases in WUE in response to drought were similar for all species at the ponderosa pine/mixed conifer ecotone. Low elevation populations of P. ponderosa had greater growth response to drought than high-elevation populations, whereas populations had a similar increase in WUE in response to drought. Our findings of different responses to drought among co-occurring tree species and between low- and high-elevation populations are interpreted in the context of drought impacts on montane coniferous forests of the southwestern USA.

  2. Decomposition of conifer tree bark under field conditions: effects of nitrogen and phosphorus additions

    NASA Astrophysics Data System (ADS)

    Lopes de Gerenyu, Valentin; Kurganova, Irina; Kapitsa, Ekaterina; Shorokhova, Ekaterina

    2016-04-01

    In forest ecosystems, the processes of decomposition of coarse woody debris (CWD) can contribute significantly to the emission component of carbon (C) cycle and thus accelerate the greenhouse effect and global climate change. A better understanding of decomposition of CWD is required to refine estimates of the C balance in forest ecosystems and improve biogeochemical models. These estimates will in turn contribute to assessing the role of forests in maintaining their long-term productivity and other ecosystems services. We examined the decomposition rate of coniferous bark with added nitrogen (N) and phosphorus (P) fertilizers in experiment under field conditions. The experiment was carried out in 2015 during 17 weeks in Moscow region (54o50'N, 37o36'E) under continental-temperate climatic conditions. The conifer tree bark mixture (ca. 70% of Norway spruce and 30% of Scots pine) was combined with soil and placed in piles of soil-bark substrate (SBS) with height of ca. 60 cm and surface area of ca. 3 m2. The dry mass ratio of bark to soil was 10:1. The experimental design included following treatments: (1) soil (Luvisols Haplic) without bark, (S), (2) pure SBS, (3) SBS with N addition in the amount of 1% of total dry bark mass (SBS-N), and (4) SBS with N and P addition in the amount of 1% of total dry bark mass for each element (SBS-NP). The decomposition rate expressed as CO2 emission flux, g C/m2/h was measured using closed chamber method 1-3 times per week from July to early November using LiCor 6400 (Nebraska, USA). During the experiment, we also controlled soil temperature at depths of 5, 20, 40, and 60 cm below surface of SBS using thermochrons iButton (DS1921G, USA). The pattern of CO2 emission rate from SBS depended strongly on fertilizing. The highest decomposition rates (DecR) of 2.8-5.6 g C/m2/h were observed in SBS-NP treatment during the first 6 weeks of experiment. The decay process of bark was less active in the treatment with only N addition. In this

  3. Modularity of Conifer Diterpene Resin Acid Biosynthesis: P450 Enzymes of Different CYP720B Clades Use Alternative Substrates and Converge on the Same Products.

    PubMed

    Geisler, Katrin; Jensen, Niels Berg; Yuen, Macaire M S; Madilao, Lina; Bohlmann, Jörg

    2016-05-01

    Cytochrome P450 enzymes of the CYP720B subfamily play a central role in the biosynthesis of diterpene resin acids (DRAs), which are a major component of the conifer oleoresin defense system. CYP720Bs exist in families of up to a dozen different members in conifer genomes and fall into four different clades (I-IV). Only two CYP720B members, loblolly pine (Pinus taeda) PtCYP720B1 and Sitka spruce (Picea sitchensis) PsCYP720B4, have been characterized previously. Both are multisubstrate and multifunctional clade III enzymes, which catalyze consecutive three-step oxidations in the conversion of diterpene olefins to DRAs. These reactions resemble the sequential diterpene oxidations affording ent-kaurenoic acid from ent-kaurene in gibberellin biosynthesis. Here, we functionally characterized the CYP720B clade I enzymes CYP720B2 and CYP720B12 in three different conifer species, Sitka spruce, lodgepole pine (Pinus contorta), and jack pine (Pinus banksiana), and compared their activities with those of the clade III enzymes CYP720B1 and CYP720B4 of the same species. Unlike the clade III enzymes, clade I enzymes were ultimately found not to be active with diterpene olefins but converted the recently discovered, unstable diterpene synthase product 13-hydroxy-8(14)-abietene. Through alternative routes, CYP720B enzymes of both clades produce some of the same profiles of conifer oleoresin DRAs (abietic acid, neoabietic acid, levopimaric acid, and palustric acid), while clade III enzymes also function in the formation of pimaric acid, isopimaric acid, and sandaracopimaric acid. These results highlight the modularity of the specialized (i.e. secondary) diterpene metabolism, which produces conifer defense metabolites through variable combinations of different diterpene synthase and CYP720B enzymes. PMID:26936895

  4. Modularity of Conifer Diterpene Resin Acid Biosynthesis: P450 Enzymes of Different CYP720B Clades Use Alternative Substrates and Converge on the Same Products.

    PubMed

    Geisler, Katrin; Jensen, Niels Berg; Yuen, Macaire M S; Madilao, Lina; Bohlmann, Jörg

    2016-05-01

    Cytochrome P450 enzymes of the CYP720B subfamily play a central role in the biosynthesis of diterpene resin acids (DRAs), which are a major component of the conifer oleoresin defense system. CYP720Bs exist in families of up to a dozen different members in conifer genomes and fall into four different clades (I-IV). Only two CYP720B members, loblolly pine (Pinus taeda) PtCYP720B1 and Sitka spruce (Picea sitchensis) PsCYP720B4, have been characterized previously. Both are multisubstrate and multifunctional clade III enzymes, which catalyze consecutive three-step oxidations in the conversion of diterpene olefins to DRAs. These reactions resemble the sequential diterpene oxidations affording ent-kaurenoic acid from ent-kaurene in gibberellin biosynthesis. Here, we functionally characterized the CYP720B clade I enzymes CYP720B2 and CYP720B12 in three different conifer species, Sitka spruce, lodgepole pine (Pinus contorta), and jack pine (Pinus banksiana), and compared their activities with those of the clade III enzymes CYP720B1 and CYP720B4 of the same species. Unlike the clade III enzymes, clade I enzymes were ultimately found not to be active with diterpene olefins but converted the recently discovered, unstable diterpene synthase product 13-hydroxy-8(14)-abietene. Through alternative routes, CYP720B enzymes of both clades produce some of the same profiles of conifer oleoresin DRAs (abietic acid, neoabietic acid, levopimaric acid, and palustric acid), while clade III enzymes also function in the formation of pimaric acid, isopimaric acid, and sandaracopimaric acid. These results highlight the modularity of the specialized (i.e. secondary) diterpene metabolism, which produces conifer defense metabolites through variable combinations of different diterpene synthase and CYP720B enzymes.

  5. Modularity of Conifer Diterpene Resin Acid Biosynthesis: P450 Enzymes of Different CYP720B Clades Use Alternative Substrates and Converge on the Same Products1[OPEN

    PubMed Central

    Yuen, Macaire M.S.; Bohlmann, Jörg

    2016-01-01

    Cytochrome P450 enzymes of the CYP720B subfamily play a central role in the biosynthesis of diterpene resin acids (DRAs), which are a major component of the conifer oleoresin defense system. CYP720Bs exist in families of up to a dozen different members in conifer genomes and fall into four different clades (I–IV). Only two CYP720B members, loblolly pine (Pinus taeda) PtCYP720B1 and Sitka spruce (Picea sitchensis) PsCYP720B4, have been characterized previously. Both are multisubstrate and multifunctional clade III enzymes, which catalyze consecutive three-step oxidations in the conversion of diterpene olefins to DRAs. These reactions resemble the sequential diterpene oxidations affording ent-kaurenoic acid from ent-kaurene in gibberellin biosynthesis. Here, we functionally characterized the CYP720B clade I enzymes CYP720B2 and CYP720B12 in three different conifer species, Sitka spruce, lodgepole pine (Pinus contorta), and jack pine (Pinus banksiana), and compared their activities with those of the clade III enzymes CYP720B1 and CYP720B4 of the same species. Unlike the clade III enzymes, clade I enzymes were ultimately found not to be active with diterpene olefins but converted the recently discovered, unstable diterpene synthase product 13-hydroxy-8(14)-abietene. Through alternative routes, CYP720B enzymes of both clades produce some of the same profiles of conifer oleoresin DRAs (abietic acid, neoabietic acid, levopimaric acid, and palustric acid), while clade III enzymes also function in the formation of pimaric acid, isopimaric acid, and sandaracopimaric acid. These results highlight the modularity of the specialized (i.e. secondary) diterpene metabolism, which produces conifer defense metabolites through variable combinations of different diterpene synthase and CYP720B enzymes. PMID:26936895

  6. Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale

    PubMed Central

    Carnicer, Jofre; Barbeta, Adrià; Sperlich, Dominik; Coll, Marta; Peñuelas, Josep

    2013-01-01

    Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenology in their productivity, in their growth allometry, and in their sensitivity to competition. Moreover, angiosperms and conifers significantly differ in hydraulic safety margins, sensitivity of stomatal conductance to vapor-pressure deficit (VPD), xylem recovery capacity or the rate of carbon transfer. These differences could be explained by key features of the xylem such as non-structural carbohydrate content (NSC), wood parenchymal fraction or wood capacitance. We suggest that the reviewed trait differences define two contrasting ecophysiological strategies that may determine qualitatively different growth responses to increased temperature and drought. Improved reciprocal common garden experiments along altitudinal or latitudinal gradients would be key to quantify the relative importance of the different hypotheses reviewed. Finally, we show that warming impacts in this area occur in an ecological context characterized by the advance of forest succession and increased dominance of angiosperm trees over extensive areas. In this context, we examined the empirical relationships between the responses of tree growth to temperature and hydraulic safety margins in angiosperm and coniferous trees. Our findings suggest a future scenario in Mediterranean forests characterized by contrasting demographic responses in conifer and angiosperm trees to both temperature and forest succession, with increased dominance of angiosperm trees, and particularly negative impacts in pines. PMID

  7. Spatial and temporal population genetic variation and structure of Nothotsuga longibracteata (Pinaceae), a relic conifer species endemic to subtropical China

    PubMed Central

    Qiu, Yingjun; Liu, Yifei; Kang, Ming; Yi, Guanmei; Huang, Hongwen

    2013-01-01

    Nothotsuga longibracteata, a relic and endangered conifer species endemic to subtropical China, was studied for examining the spatial-temporal population genetic variation and structure to understand the historical biogeographical processes underlying the present geographical distribution. Ten populations were sampled over the entire natural range of the species for spatial analysis, while three key populations with large population sizes and varied age structure were selected for temporal analyses using both nuclear microsatellites (nSSR) and chloroplast microsatellites (cpSSR). A recent bottleneck was detected in the natural populations of N. longibracteata. The spatial genetic analysis showed significant population genetic differentiation across its total geographical range. Notwithstanding, the temporal genetic analysis revealed that the level of genetic diversity between different age class subpopulations remained constant over time. Eleven refugia of the Last Glacial Maximum were identified, which deserve particular attention for conservation management. PMID:24385864

  8. Development of 23 novel polymorphic EST-SSR markers for the endangered relict conifer Metasequoia glyptostroboides1

    PubMed Central

    Jin, Yuqing; Bi, Quanxin; Guan, Wenbin; Mao, Jian-Feng

    2015-01-01

    Premise of the study: Metasequoia glyptostroboides is an endangered relict conifer species endemic to China. In this study, expressed sequence tag–simple sequence repeat (EST-SSR) markers were developed using transcriptome mining for future genetic and functional studies. Methods and Results: We collected 97,565 unigene sequences generated by 454 pyrosequencing. A bioinformatics analysis identified 2087 unique and putative microsatellites, from which 96 novel microsatellite markers were developed. Fifty-three of the 96 primer sets successfully amplified clear fragments of the expected sizes; 23 of those loci were polymorphic. The number of alleles per locus ranged from two to eight, with an average of three, and the observed and expected heterozygosity values ranged from 0 to 1.0 and 0.117 to 0.813, respectively. Conclusions: These microsatellite loci will enrich the genetic resources to develop functional studies and conservation strategies for this endangered relict species. PMID:26421250

  9. Analysis of the dielectric properties of trunk wood in dominant conifer species from New England and Siberia

    NASA Technical Reports Server (NTRS)

    Ranson, K. J.; Rock, B. N.; Salas, W. A.; Smith, K.; Williams, D. L.

    1992-01-01

    Data were collected for dominant conifer species. Dielectric properties of trunk wood were measured using a C-band dielectric probe. For certain specimens, electrical resistance was also measured using a shigometer. The water status of the trees studies was determined either by use of a Scholander pressure chamber on branch samples collected simultaneously with dielectric measurements or by fresh-weight/dry-weight assessment of wood core samples extracted and analyzed with the dielectric probe and shigometer. Diurnal delectric properties and xylem water column tension are inversely correlated such that real and imaginary dielectric values drop as tension increases. The dielectric properties were positively correlated with wood core moisture content while electrical resistance was poorly correlated with wood core moisture content in one species studied. Results support the view that dielectric properties are strongly correlated with moisture status in trunk wood, and possibly ion concentrations associated with decay processes in damaged specimens.

  10. Stem Densities of Trees from Overstocked Mixed Conifer Stands of Western Hemlock, Douglas-fir and Western Redcedar.

    SciTech Connect

    Pong, W.Y.; Waddell, Dale R.; Biomass and Energy Project

    1985-03-15

    This report presents results from a stem density (wood and bark combined) study conducted on trees from overstocked mixed conifer stands of Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata) located on the Quilcene Ranger District, Olympic National Forest in the State of Washington. Information on the density of stem wood that is available in literature generally have been derived from trees growing in stands of normal stocking levels. Stem densities, an essential parameter in the determination of stem biomass, have not been investigated for trees growing in overstocked conditions. Predictive estimators of density based on data derived from studies of normally stocked stands can not be applied to trees growing in an overstocked condition with any reliability. There is need to specifically examine stem densities in trees grown under these adverse conditions. 3 refs., 3 tabs.

  11. Sapling leaf trait responses to light, tree height and soil nutrients for three conifer species of contrasting shade tolerance.

    PubMed

    Lilles, Erica B; Astrup, Rasmus; Lefrançois, Marie-Lou; David Coates, K

    2014-12-01

    We developed models to describe the responses of four commonly examined leaf traits (mass per area, weight, area and nitrogen (N) concentration) to gradients of light, soil nutrients and tree height in three conifer species of contrasting shade tolerance. Our observational dataset from the sub-boreal spruce forests of British Columbia included subalpine fir (Abies lasioscarpa [Hook.] Nutt; high shade tolerance), interior spruce (Picea glauca × Picea engelmannii [Moench] Voss; intermediate shade tolerance) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia; low shade tolerance) saplings from 0.18 to 4.87 m tall, in 8-98% of total incident light, from field sites with <17.6 kg ha(-1) to >46.8 kg ha(-1) total dissolved N. Leaf weights and areas showed strong positive responses to light and height, but little or no response to soil nutrients. Parameter estimates indicated that the shape of leaf weight and area responses to light corresponded with shade tolerance ranking for the three species; pine had the most linear response whereas spruce and fir had asymptotic responses. Leaf N concentration responded positively to soil nutrients, negatively to light and idiosyncratically to height. The negative effect of light was only apparent on sites of high soil nutrient availability, and parameter estimates for the shape of the negative response also corresponded to shade tolerance ranking (apine = -0.79, aspruce = -0.15, afir = -0.07). Of the traits we measured, leaf mass per area showed the least response to light, soil nutrient and height gradients. Although it is a common practice in comparisons across many species, characterizing these conifers by mean values of their leaf traits would miss important intraspecific variation across environmental and size gradients. In these forests, parameter estimates representing the intraspecific variability of leaf trait responses can be used to understand relative shade tolerances. PMID

  12. Contrasting Spatial Patterns in Active-Fire and Fire-Suppressed Mediterranean Climate Old-Growth Mixed Conifer Forests

    PubMed Central

    Fry, Danny L.; Stephens, Scott L.; Collins, Brandon M.; North, Malcolm P.; Franco-Vizcaíno, Ernesto; Gill, Samantha J.

    2014-01-01

    In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha−1, and occupied 27–46% of the study areas. Average canopy gap sizes (0.04 ha) covering 11–20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥56%) in large patches (≥10 trees), and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types. PMID:24586472

  13. Contrasting spatial patterns in active-fire and fire-suppressed Mediterranean climate old-growth mixed conifer forests.

    PubMed

    Fry, Danny L; Stephens, Scott L; Collins, Brandon M; North, Malcolm P; Franco-Vizcaíno, Ernesto; Gill, Samantha J

    2014-01-01

    In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha(-1), and occupied 27-46% of the study areas. Average canopy gap sizes (0.04 ha) covering 11-20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥ 56%) in large patches (≥ 10 trees), and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types.

  14. Differences in the response sensitivity of stomatal index to atmospheric CO2 among four genera of Cupressaceae conifers

    PubMed Central

    Haworth, Matthew; Heath, James; McElwain, Jennifer C.

    2010-01-01

    Background and Aims The inverse relationship between stomatal density (SD: number of stomata per mm2 leaf area) and atmospheric concentration of CO2 ([CO2]) permits the use of plants as proxies of palaeo-atmospheric CO2. Many stomatal reconstructions of palaeo-[CO2] are based upon multiple fossil species. However, it is unclear how plants respond to [CO2] across genus, family or ecotype in terms of SD or stomatal index (SI: ratio of stomata to epidermal cells). This study analysed the stomatal numbers of conifers from the ancient family Cupressaceae, in order to examine the nature of the SI–[CO2] relationship, and potential implications for stomatal reconstructions of palaeo-[CO2]. Methods Stomatal frequency measurements were taken from historical herbarium specimens of Athrotaxis cupressoides, Tetraclinis articulata and four Callitris species, and live A. cupressoides grown under CO2-enrichment (370, 470, 570 and 670 p.p.m. CO2). Key Results T. articulata, C. columnaris and C. rhomboidea displayed significant reductions in SI with rising [CO2]; by contrast, A. cupressoides, C. preissii and C. oblonga show no response in SI. However, A. cupressoides does reduce SI to increases in [CO2] above current ambient (approx. 380 p.p.m. CO2). This dataset suggests that a shared consistent SI–[CO2] relationship is not apparent across the genus Callitris. Conclusions The present findings suggest that it is not possible to generalize how conifer species respond to fluctuations in [CO2] based upon taxonomic relatedness or habitat. This apparent lack of a consistent response, in conjunction with high variability in SI, indicates that reconstructions of absolute palaeo-[CO2] based at the genus level, or upon multiple species for discrete intervals of time are not as reliable as those based on a single or multiple temporally overlapping species. PMID:20089556

  15. Conifer Encroachment into Tuolumne Meadows, Yosemite National Park: How Anthropogenic Impacts to Local Hydrology Affect Meadow Habitat

    NASA Astrophysics Data System (ADS)

    Roche, J. W.; Lundquist, J. L.; Cooper, D. J.; King, J. C.; Flint, L. E.; Flint, A. L.

    2006-12-01

    Tuolumne Meadows, at 2600 m in Yosemite National Park, is one of the most popular sub-alpine destinations in the Sierra Nevada of California and, as such, one of the most impacted by current and historic use. Conifer (lodgepole pine) encroachment into the meadow has been managed for over 70 years to maintain vistas and to protect potentially impacted meadow vegetation. This study seeks to characterize hydrologic, soil, and vegetation assemblages throughout the affected area, document departures from expected relationships, and identify causative disruptive mechanisms. The snowmelt-dominated Tuolumne River, an integral part of the meadow system, drains 200 km{2} of the Sierra Nevada crest above the meadows. Much of the meadow area consists of recently glaciated granitic bedrock overlain by 1-2 meters of alluvial sand and gravel topped with 30-40 cm of organic-rich meadow soil. Almost all areas examined to date reveal plant assemblages and hydrologic regimes that are inconsistent with the formation of these meadow soils. In upland sites, this is characterized by groundwater conditions that are incapable of supporting meadow forming vegetation and soils. In lower areas, where groundwater levels remain close to the surface throughout the summer, the vegetation present lacks plant species with high below ground biomass production, and could not have formed the existing meadow soils. Potential mechanisms for these disruptions include ditching associated with road construction and drainage, changes in river morphology due to loss of willow riparian vegetation, and lingering impacts of intensive grazing more than a century ago. Patterns of conifer invasion as well as tree-ring and fire scar chronologies were also documented and appear to reflect similar responses to the impacts mentioned above. Results of this study are intended to inform future management and possible restoration of the area.

  16. Estimating leaf-level parameters for ecosystem process models: a study in mixed conifer canopies on complex terrain.

    PubMed

    Duursma, Remko A; Marshall, John D; Nippert, Jesse B; Chambers, Chris C; Robinson, Andrew P

    2005-11-01

    Ecosystem process models are often used to predict carbon flux on a landscape or on a global scale. Such models must be aggregate and canopies are often treated as a uniform unit of foliage. Parameters that are known to vary within the canopy, e.g., nitrogen content and leaf mass per area, are often estimated by a mean value for the canopy. Estimating appropriate means is complicated, especially in mixed-species stands and in complex terrain. We analyzed sources of variation in specific parameters with the goal of testing various simplifying assumptions. The measurements came from mixed-species forests in the northern Rocky Mountains. We found that, for three important parameters (nitrogen concentration and content, and leaf mass per area), a sample taken near the vertical center of the crown provided a good estimate of the mean values for the crown. Altitude (700-1700 m), solar insolation (4200-5400 MJ m(-2) year(-1)) and leaf area index (1-11) had negligible effects on the parameters; only species differences were consistently detected. The correlation between mass-based photosynthetic rates and mass-based nitrogen concentrations was much weaker than the correlation between area-based photosynthetic rates and area-based nitrogen concentration. Comparison of photosynthesis-nitrogen relationships for a wide variety of conifer species and sites revealed a broad general trend that can be used in models. These results suggest important potential simplifications in model parameterization, most notably that canopy means can be estimated with ease, that complex terrain is a minor source of variation in these parameters and that use of one photosynthesis-nitrogen relationship for conifer species does not result in large errors. Species-to-species variation, however, was large and needs to be accounted for when parameterizing process models. PMID:16105802

  17. Sapling leaf trait responses to light, tree height and soil nutrients for three conifer species of contrasting shade tolerance.

    PubMed

    Lilles, Erica B; Astrup, Rasmus; Lefrançois, Marie-Lou; David Coates, K

    2014-12-01

    We developed models to describe the responses of four commonly examined leaf traits (mass per area, weight, area and nitrogen (N) concentration) to gradients of light, soil nutrients and tree height in three conifer species of contrasting shade tolerance. Our observational dataset from the sub-boreal spruce forests of British Columbia included subalpine fir (Abies lasioscarpa [Hook.] Nutt; high shade tolerance), interior spruce (Picea glauca × Picea engelmannii [Moench] Voss; intermediate shade tolerance) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia; low shade tolerance) saplings from 0.18 to 4.87 m tall, in 8-98% of total incident light, from field sites with <17.6 kg ha(-1) to >46.8 kg ha(-1) total dissolved N. Leaf weights and areas showed strong positive responses to light and height, but little or no response to soil nutrients. Parameter estimates indicated that the shape of leaf weight and area responses to light corresponded with shade tolerance ranking for the three species; pine had the most linear response whereas spruce and fir had asymptotic responses. Leaf N concentration responded positively to soil nutrients, negatively to light and idiosyncratically to height. The negative effect of light was only apparent on sites of high soil nutrient availability, and parameter estimates for the shape of the negative response also corresponded to shade tolerance ranking (apine = -0.79, aspruce = -0.15, afir = -0.07). Of the traits we measured, leaf mass per area showed the least response to light, soil nutrient and height gradients. Although it is a common practice in comparisons across many species, characterizing these conifers by mean values of their leaf traits would miss important intraspecific variation across environmental and size gradients. In these forests, parameter estimates representing the intraspecific variability of leaf trait responses can be used to understand relative shade tolerances.

  18. Role of acid and aluminum-rich media in the growth and nutrition of Pacific Northwest conifers

    SciTech Connect

    Ryan, P.J.

    1983-01-01

    Forest soils of coastal Washington and Oregon tend to be very acidic with large accumulations of organic matter. Yet the productivity of forest species on these sites can attain record levels. The effect of acid and aluminum-rich media on the growth and nutrition of Pacific Northwest conifer species was investigated for western hemlock, Douglas-fir, western redcedar, and Sitka spruce. The four different types of growth media utilized were solution cultures, sand cultures, mineral soils, and forest floor organic matter. Hydroponic nutrient solutions and sand cultures were used in experiments designed to differentiate the effect of aluminum ions from the hydrogen ions generated by hydrolysis of Al/sup 3 +/. Relative to agronomic plants, all the conifers were found tolerant of the acid solutions and high levels of aluminum. Species differed in their relative tolerance to H/sup +/ and Al/sup 3/ ions. Western hemlock seedling growth was superior to Douglas-fir in the acidified soils and forest floor media, while Ca(OH)/sub 2/ amendment favored Douglas-fir. The marginal increase in western hemlock growth in N + P treated soils was highest in acidified soils. Western hemlock exhibited an ability to absorb nutrients in the presence of excess solution H/sup +/ ions, maintain growth with low tissue requirements of Ca and Mg, and accumulate high levels of aluminum in its roots and foliage without major adverse effect. These attributes are considered to make western hemlock the most acid and Al-tolerant of the four Pacific Northwest forest species studied. Western redcedar was second in acid tolerance to western hemlock. This species' ability to accumulate Ca minimized Al absorption and H/sup +/ damage to its roots.

  19. Extraction and estimation of the quantity of calcium oxalate crystals in the foliage of conifer and hardwood trees.

    PubMed

    Minocha, Rakesh; Chamberlain, Bradley; Long, Stephanie; Turlapati, Swathi A; Quigley, Gloria

    2015-05-01

    The main goal of this study was to develop a method for the extraction and indirect estimation of the quantity of calcium oxalate (CaOx) in the foliage of trees. Foliar tissue was collected from a single tree of each species (five conifers and five hardwoods) for comparison of extractions in different solvents using 10 replicates per species from the same pool of tissue. For each species, calcium (Ca) and oxalate were extracted sequentially in double deionized water and 2N acetic acid, and finally, five replicate samples were extracted in 5% (0.83N) perchloric acid (PCA) and the other five in 2N hydrochloric acid (HCl); three cycles of freezing and thawing were used for each solvent. Total ions were extracted by microwave digestion. Calcium was quantified with an inductively coupled plasma emission spectrophotometer method and oxalate was eluted and quantified using a high performance liquid chromatography method. This experiment was repeated again with two conifer and two hardwood species using four trees per species, and two analytical replicates for each tree. We report here that, regardless of age of individual trees within a species, time of collection or species type, the third extraction in PCA or HCl resulted in near equimolar quantities of Ca and oxalate (r(2) ≥ 0.99). This method provides an easy estimate of the quantity of CaOx crystals using a small sample of foliar tissue. An additional benefit of PCA is that it precipitates the nucleic acids and proteins, allowing the quantification of several free/soluble metabolites such as amino acids, polyamines, organic acids and inorganic elements all from a single sample extract. PMID:25934989

  20. Evolution of gene structure in the conifer Picea glauca: a comparative analysis of the impact of intron size

    PubMed Central

    2014-01-01

    Background A positive relationship between genome size and intron length is observed across eukaryotes including Angiosperms plants, indicating a co-evolution of genome size and gene structure. Conifers have very large genomes and longer introns on average than most plants, but impacts of their large genome and longer introns on gene structure has not be described. Results Gene structure was analyzed for 35 genes of Picea glauca obtained from BAC sequencing and genome assembly, including comparisons with A. thaliana, P. trichocarpa and Z. mays. We aimed to develop an understanding of impact of long introns on the structure of individual genes. The number and length of exons was well conserved among the species compared but on average, P. glauca introns were longer and genes had four times more intronic sequence than Arabidopsis, and 2 times more than poplar and maize. However, pairwise comparisons of individual genes gave variable results and not all contrasts were statistically significant. Genes generally accumulated one or a few longer introns in species with larger genomes but the position of long introns was variable between plant lineages. In P. glauca, highly expressed genes generally had more intronic sequence than tissue preferential genes. Comparisons with the Pinus taeda BACs and genome scaffolds showed a high conservation for position of long introns and for sequence of short introns. A survey of 1836 P. glauca genes obtained by sequence capture mostly containing introns <1 Kbp showed that repeated sequences were 10× more abundant in introns than in exons. Conclusion Conifers have large amounts of intronic sequence per gene for seed plants due to the presence of few long introns and repetitive element sequences are ubiquitous in their introns. Results indicate a complex landscape of intron sizes and distribution across taxa and between genes with different expression profiles. PMID:24734980

  1. Extraction and estimation of the quantity of calcium oxalate crystals in the foliage of conifer and hardwood trees.

    PubMed

    Minocha, Rakesh; Chamberlain, Bradley; Long, Stephanie; Turlapati, Swathi A; Quigley, Gloria

    2015-05-01

    The main goal of this study was to develop a method for the extraction and indirect estimation of the quantity of calcium oxalate (CaOx) in the foliage of trees. Foliar tissue was collected from a single tree of each species (five conifers and five hardwoods) for comparison of extractions in different solvents using 10 replicates per species from the same pool of tissue. For each species, calcium (Ca) and oxalate were extracted sequentially in double deionized water and 2N acetic acid, and finally, five replicate samples were extracted in 5% (0.83N) perchloric acid (PCA) and the other five in 2N hydrochloric acid (HCl); three cycles of freezing and thawing were used for each solvent. Total ions were extracted by microwave digestion. Calcium was quantified with an inductively coupled plasma emission spectrophotometer method and oxalate was eluted and quantified using a high performance liquid chromatography method. This experiment was repeated again with two conifer and two hardwood species using four trees per species, and two analytical replicates for each tree. We report here that, regardless of age of individual trees within a species, time of collection or species type, the third extraction in PCA or HCl resulted in near equimolar quantities of Ca and oxalate (r(2) ≥ 0.99). This method provides an easy estimate of the quantity of CaOx crystals using a small sample of foliar tissue. An additional benefit of PCA is that it precipitates the nucleic acids and proteins, allowing the quantification of several free/soluble metabolites such as amino acids, polyamines, organic acids and inorganic elements all from a single sample extract.

  2. Historical dominance of low-severity fire in dry and wet mixed-conifer forest habitats of the endangered terrestrial Jemez Mountains salamander (Plethodon neomexicanus)

    USGS Publications Warehouse

    Margolis, Ellis; Malevich, Steven B.

    2016-01-01

    Anthropogenic alteration of ecosystem processes confounds forest management and conservation of rare, declining species. Restoration of forest structure and fire hazard reduction are central goals of forest management policy in the western United States, but restoration priorities and treatments have become increasingly contentious. Numerous studies have documented changes in fire regimes, forest stand structure and species composition following a century of fire exclusion in dry, frequent-fire forests of the western U.S. (e.g., ponderosa pine and dry mixed-conifer). In contrast, wet mixed-conifer forests are thought to have historically burned infrequently with mixed- or high-severity fire—resulting in reduced impacts from fire exclusion and low restoration need—but data are limited. In this study we quantified the current forest habitat of the federally endangered, terrestrial Jemez Mountains salamander (Plethodon neomexicanus) and compared it to dendroecological reconstructions of historical habitat (e.g., stand structure and composition), and fire regime parameters along a gradient from upper ponderosa pine to wet mixed-conifer forests. We found that current fire-free intervals in Jemez Mountains salamander habitat (116–165 years) are significantly longer than historical intervals, even in wet mixed-conifer forests. Historical mean fire intervals ranged from 10 to 42 years along the forest gradient. Low-severity fires were historically dominant across all forest types (92 of 102 fires). Although some mixed- or highseverity fire historically occurred at 67% of the plots over the last four centuries, complete mortality within 1.0 ha plots was rare, and asynchronous within and among sites. Climate was an important driver of temporal variability in fire severity, such that mixed- and high-severity fires were associated with more extreme drought than low-severity fires. Tree density in dry conifer forests historically ranged from open (90 trees/ha) to

  3. A Long-Term Assessment of the Variability in Winter Use of Dense Conifer Cover by Female White-Tailed Deer

    PubMed Central

    DelGiudice, Glenn D.; Fieberg, John R.; Sampson, Barry A.

    2013-01-01

    Backgound Long-term studies allow capture of a wide breadth of environmental variability and a broader context within which to maximize our understanding of relationships to specific aspects of wildlife behavior. The goal of our study was to improve our understanding of the biological value of dense conifer cover to deer on winter range relative to snow depth and ambient temperature. Methodology/Principal Findings We examined variation among deer in their use of dense conifer cover during a 12-year study period as potentially influenced by winter severity and cover availability. Female deer were fitted with a mixture of very high frequency (VHF, n = 267) and Global Positioning System (GPS, n = 24) collars for monitoring use of specific cover types at the population and individual levels, respectively. We developed habitat composites for four study sites. We fit multinomial response models to VHF (daytime) data to describe population-level use patterns as a function of snow depth, ambient temperature, and cover availability. To develop alternative hypotheses regarding expected spatio-temporal patterns in the use of dense conifer cover, we considered two sets of competing sub-hypotheses. The first set addressed whether or not dense conifer cover was limiting on the four study sites. The second set considered four alternative sub-hypotheses regarding the potential influence of snow depth and ambient temperature on space use patterns. Deer use of dense conifer cover increased the most with increasing snow depth and most abruptly on the two sites where it was most available, suggestive of an energy conservation strategy. Deer use of dense cover decreased the most with decreasing temperatures on the sites where it was most available. At all four sites deer made greater daytime use (55 to >80% probability of use) of open vegetation types at the lowest daily minimum temperatures indicating the importance of thermal benefits afforded from increased exposure to solar

  4. Assessment of acidic deposition and ozone effects on conifer forests in the San Bernardino Mountains. Standard operating procedure manual. Volume 1. Final report

    SciTech Connect

    Miller, P.R.; Chow, J.; Watson, J.G.

    1994-11-30

    The purpose of this study was to evaluate the separate and combined effects of ozone and acidic deposition on mixed conifer forests in the San Bernardino mountains of southern California. The primary objectives were to acquire a long-term data base of specified accuracy, precision and validity for atmospheric pollution concentration, local and stand meteorology, wet and dry deposition fluxes to forest canopies, and biological responses of forest vegetation and soils. Some data were used to parameterize and run simulations with the Big Leaf model. Futhermore, to document the procedures used in the project, complete descriptions of measurement techniques, research protocols and quality assurace objectives were compiled in a companion document to the final report. This multi-disciplinary study provides a data base describing many attributes of a California mixed conifer forest ecosystem exposed to a moderate level of gas and particle deposition compared to the highest possible levels in the western portions of the San Bernardino mountains.

  5. Assessment of acidic deposition and ozone effects on conifer forests in the San Bernardino Mountains. Standard operating procedure manual. Volume 2. Final report

    SciTech Connect

    Miller, P.R.; Chow, J.; Watson, J.G.

    1994-11-30

    The purpose of this study was to evaluate the separate and combined effects of ozone and acidic deposition on mixed conifer forests in the San Bernardino mountains of southern California. The primary objectives were to acquire a long-term data base of specified accuracy, precision and validity for atmospheric pollution concentration, local and stand meteorology, wet and dry deposition fluxes to forest canopies, and biological responses of forest vegetation and soils. Some data were used to parameterize and run simulations with the Big Leaf model. Futhermore, to document the procedures used in the project, complete descriptions of measurement techniques, research protocols and quality assurace objectives were compiled in a companion document to the final report. This multi-disciplinary study provides a data base describing many attributes of a California mixed conifer forest ecosystem exposed to a moderate level of gas and particle deposition compared to the highest possible levels in the western portions of the San Bernardino mountains.

  6. Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

    USGS Publications Warehouse

    Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

    2006-01-01

    Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

  7. Mutational analysis of white spruce (Picea glauca) ent-kaurene synthase (PgKS) reveals common and distinct mechanisms of conifer diterpene synthases of general and specialized metabolism.

    PubMed

    Zerbe, Philipp; Chiang, Angela; Bohlmann, Jörg

    2012-02-01

    Conifer diterpene synthases (diTPSs) catalyze the multi-step cycloisomerization of geranylgeranyl diphosphate, or copalyl diphosphate, to a variety of diterpenes in general (i.e., primary) and specialized (i.e., secondary) metabolism. Despite their functional diversity, the known conifer diTPSs are structurally closely related, with variations in three conserved domains, α, β and γ. The catalytic specificity of conifer class I and class I/II diTPSs is predominantly determined by the protein environment of the C-terminal class I active site through stabilization of common and unique carbocation intermediates. Using the crystal structure of Taxus brevifolia taxadiene synthase as template, comparative modeling and mutagenesis of the class I diTPS ent-kaurene synthase from Picea glauca (PgKS) was performed to elucidate the catalytic specificity of PgKS relative to spruce diTPSs of specialized metabolism. N-terminal truncations demonstrated a role for the βγ domain in class I enzyme activity for PgKS, facilitating the closure of the class I active site upon substrate binding. Based on position, Arg476 and Asp736 in the C-terminal α domain of PgKS may contribute to this conformational transition and appear critical for catalysis. Consistent with the mechanism of other diTPSs, the subsequent ionization of a copalyl diphosphate substrate and coordination of the diphosphate group is controlled by strictly conserved residues in the DDxxD and NDIQGCKRE motif of PgKS, such as Asn656 and Arg653. Furthermore, Lys478, Trp502, Met588, Ala615 and Ile619 control the enzymatic activity and specificity of PgKS via carbocation stabilization en route to ent-kaurene. These positions show a high level of amino acid variation, consistent with functional plasticity among conifer diTPSs of different functions in general or specialized metabolism.

  8. Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America.

    PubMed

    Odion, Dennis C; Hanson, Chad T; Arsenault, André; Baker, William L; Dellasala, Dominick A; Hutto, Richard L; Klenner, Walt; Moritz, Max A; Sherriff, Rosemary L; Veblen, Thomas T; Williams, Mark A

    2014-01-01

    There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa

  9. Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America.

    PubMed

    Odion, Dennis C; Hanson, Chad T; Arsenault, André; Baker, William L; Dellasala, Dominick A; Hutto, Richard L; Klenner, Walt; Moritz, Max A; Sherriff, Rosemary L; Veblen, Thomas T; Williams, Mark A

    2014-01-01

    There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa

  10. Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

    PubMed Central

    Odion, Dennis C.; Hanson, Chad T.; Arsenault, André; Baker, William L.; DellaSala, Dominick A.; Hutto, Richard L.; Klenner, Walt; Moritz, Max A.; Sherriff, Rosemary L.; Veblen, Thomas T.; Williams, Mark A.

    2014-01-01

    There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to “restore” forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa

  11. The stomatal CO2 proxy does not saturate at high atmospheric CO2 concentrations: evidence from stomatal index responses of Araucariaceae conifers.

    PubMed

    Haworth, Matthew; Elliott-Kingston, Caroline; McElwain, Jennifer C

    2011-09-01

    The inverse relationship between the number of stomata on a leaf surface and the atmospheric carbon dioxide concentration ([CO(2)]) in which the leaf developed allows plants to optimise water-use efficiency (WUE), but it also permits the use of fossil plants as proxies of palaeoatmospheric [CO(2)]. The ancient conifer family Araucariaceae is often represented in fossil floras and may act as a suitable proxy of palaeo-[CO(2)], yet little is known regarding the stomatal index (SI) responses of extant Araucariaceae to [CO(2)]. Four Araucaria species (Araucaria columnaris, A. heterophylla, A. angustifolia and A. bidwillii) and Agathis australis displayed no significant relationship in SI to [CO(2)] below current ambient levels (~380 ppm). However, representatives of the three extant genera within the Araucariaceae (A. bidwillii, A. australis and Wollemia nobilis) all exhibited significant reductions in SI when grown in atmospheres of elevated [CO(2)] (1,500 ppm). Stomatal conductance was reduced and WUE increased when grown under elevated [CO(2)]. Stomatal pore length did not increase alongside reduced stomatal density (SD) and SI in the three araucariacean conifers when grown at elevated [CO(2)]. These pronounced SD and SI reductions occur at higher [CO(2)] levels than in other species with more recent evolutionary origins, and may reflect an evolutionary legacy of the Araucariaceae in the high [CO(2)] world of the Mesozoic Era. Araucariacean conifers may therefore be suitable stomatal proxies of palaeo-[CO(2)] during periods of "greenhouse" climates and high [CO(2)] in the Earth's history.

  12. The Complete Chloroplast Genome Sequence of a Relict Conifer Glyptostrobus pensilis: Comparative Analysis and Insights into Dynamics of Chloroplast Genome Rearrangement in Cupressophytes and Pinaceae

    PubMed Central

    Zheng, Renhua; Xu, Haibin; Zhou, Yanwei; Li, Meiping; Lu, Fengjuan; Dong, Yini; Liu, Xin; Chen, Jinhui; Shi, Jisen

    2016-01-01

    Glyptostrobus pensilis, belonging to the monotypic genus Glyptostrobus (Family: Cupressaceae), is an ancient conifer that is naturally distributed in low-lying wet areas. Here, we report the complete chloroplast (cp) genome sequence (132,239 bp) of G. pensilis. The G. pensilis cp genome is similar in gene content, organization and genome structure to the sequenced cp genomes from other cupressophytes, especially with respect to the loss of the inverted repeat region A (IRA). Through phylogenetic analysis, we demonstrated that the genus Glyptostrobus is closely related to the genus Cryptomeria, supporting previous findings based on physiological characteristics. Since IRs play an important role in stabilize cp genome and conifer cp genomes lost different IR regions after splitting in two clades (cupressophytes and Pinaceae), we performed cp genome rearrangement analysis and found more extensive cp genome rearrangements among the species of cupressophytes relative to Pinaceae. Additional repeat analysis indicated that cupressophytes cp genomes contained less potential functional repeats, especially in Cupressaceae, compared with Pinaceae. These results suggested that dynamics of cp genome rearrangement in conifers differed since the two clades, Pinaceae and cupressophytes, lost IR copies independently and developed different repeats to complement the residual IRs. In addition, we identified 170 perfect simple sequence repeats that will be useful in future research focusing on the evolution of genetic diversity and conservation of genetic variation for this endangered species in the wild. PMID:27560965

  13. Metabolite changes in conifer buds and needles during forced bud break in Norway spruce (Picea abies) and European silver fir (Abies alba)

    PubMed Central

    Dhuli, Priyanka; Rohloff, Jens; Strimbeck, G. Richard

    2014-01-01

    Environmental changes such as early spring and warm spells induce bud burst and photosynthetic processes in cold-acclimated coniferous trees and consequently, cellular metabolism in overwintering needles and buds. The purpose of the study was to examine metabolism in conifers under forced deacclimation (artificially induced spring) by exposing shoots of Picea abies (boreal species) and Abies alba (temperate species) to a greenhouse environment (22°C, 16/8 h D/N cycle) over a 9 weeks period. Each week, we scored bud opening and collected samples for GC/MS–based metabolite profiling. We detected a total of 169 assigned metabolites and 80 identified metabolites, comprising compounds such as mono- and disaccharides, Krebs cycle acids, amino acids, polyols, phenolics, and phosphorylated structures. Untargeted multivariate statistical analysis based on PCA and cluster analysis segregated samples by species, tissue type, and stage of tissue deacclimations. Similar patterns of metabolic regulation in both species were observed in buds (amino acids, Krebs cycle acids) and needles (hexoses, pentoses, and Krebs cycle acids). Based on correlation of bud opening score with compound levels, distinct metabolites could be associated with bud and shoot development, including amino acids, sugars, and acids with known osmolyte function, and secondary metabolites. This study has shed light on how elevated temperature affects metabolism in buds and needles of conifer species during the deacclimation phase, and contributes to the discussion about how phenological characters in conifers may respond to future global warming. PMID:25566281

  14. The Complete Chloroplast Genome Sequence of a Relict Conifer Glyptostrobus pensilis: Comparative Analysis and Insights into Dynamics of Chloroplast Genome Rearrangement in Cupressophytes and Pinaceae.

    PubMed

    Hao, Zhaodong; Cheng, Tielong; Zheng, Renhua; Xu, Haibin; Zhou, Yanwei; Li, Meiping; Lu, Fengjuan; Dong, Yini; Liu, Xin; Chen, Jinhui; Shi, Jisen

    2016-01-01

    Glyptostrobus pensilis, belonging to the monotypic genus Glyptostrobus (Family: Cupressaceae), is an ancient conifer that is naturally distributed in low-lying wet areas. Here, we report the complete chloroplast (cp) genome sequence (132,239 bp) of G. pensilis. The G. pensilis cp genome is similar in gene content, organization and genome structure to the sequenced cp genomes from other cupressophytes, especially with respect to the loss of the inverted repeat region A (IRA). Through phylogenetic analysis, we demonstrated that the genus Glyptostrobus is closely related to the genus Cryptomeria, supporting previous findings based on physiological characteristics. Since IRs play an important role in stabilize cp genome and conifer cp genomes lost different IR regions after splitting in two clades (cupressophytes and Pinaceae), we performed cp genome rearrangement analysis and found more extensive cp genome rearrangements among the species of cupressophytes relative to Pinaceae. Additional repeat analysis indicated that cupressophytes cp genomes contained less potential functional repeats, especially in Cupressaceae, compared with Pinaceae. These results suggested that dynamics of cp genome rearrangement in conifers differed since the two clades, Pinaceae and cupressophytes, lost IR copies independently and developed different repeats to complement the residual IRs. In addition, we identified 170 perfect simple sequence repeats that will be useful in future research focusing on the evolution of genetic diversity and conservation of genetic variation for this endangered species in the wild. PMID:27560965

  15. delta13C and water-use efficiency in Australian grasstrees and South African conifers over the last century.

    PubMed

    Swanborough, Perry W; Lamont, Byron B; February, Edmund C

    2003-07-01

    Annual or biannual time courses of plant delta13C (delta13C(p)) over the last century (70-100 years) were recorded for leafbases of four grasstrees (Xanthorrhoea preissii) at four sites in mediterranean Australia and wood of four conifers (Widdringtonia cedarbergensis) at two sites in mediterranean South Africa. There was a strong downward trend of 2-5.5(per thousand ) from 1935 to 1940 to the present in the eight plants. Trends were more variable from 1900 to 1940 with plants at two sites of each species showing an upward trend of 1-2.5 per thousand. Accepting that delta13C of the air (delta13C(a)) fell by almost 2 per thousand over the last century, the ratio of leaf intercellular CO2 to atmospheric CO2 (c(i)/c(a)) rose in five plants and remained unchanged in three over that period. Changes in c(i)/c(a) rather than delta13C(a) were more closely correlated with changes in delta13C(p) and accounted for 6.7-71.8% (22.6 c(i)/c(a)) and 28.2-93.3% (delta13C(a)) of the variation in delta13C(p). We doubt that possible changing patterns of rainfall, water availability, temperature, shade, air pollution or clearing for agriculture have contributed to the overall trend for c(i)/c(a) to rise over time. Instead, we provide evidence (concentrations of Fe and Mn in the grasstree leafbases) that decreasing photosynthetic capacity associated with falling nutrient availability due to the reduced occurrence of fire may have contributed to rising c(i)/c(a). Intrinsic water-use efficiency (W(i)) as a function of (c(a)-c(i)) usually increased linearly over the period, with the two exceptions explained by their marked increase in c(i)/c(a). We conclude that grasstrees may provide equivalent delta13C(p )and W(i) data to long-lived conifers and that their interpretation requires a consideration of the causes of variation in both c(i)/c(a )and delta13C(a). PMID:12728309

  16. MADS goes genomic in conifers: towards determining the ancestral set of MADS-box genes in seed plants

    PubMed Central

    Gramzow, Lydia; Weilandt, Lisa; Theißen, Günter

    2014-01-01

    Background and Aims MADS-box genes comprise a gene family coding for transcription factors. This gene family expanded greatly during land plant evolution such that the number of MADS-box genes ranges from one or two in green algae to around 100 in angiosperms. Given the crucial functions of MADS-box genes for nearly all aspects of plant development, the expansion of this gene family probably contributed to the increasing complexity of plants. However, the expansion of MADS-box genes during one important step of land plant evolution, namely the origin of seed plants, remains poorly understood due to the previous lack of whole-genome data for gymnosperms. Methods The newly available genome sequences of Picea abies, Picea glauca and Pinus taeda were used to identify the complete set of MADS-box genes in these conifers. In addition, MADS-box genes were identified in the growing number of transcriptomes available for gymnosperms. With these datasets, phylogenies were constructed to determine the ancestral set of MADS-box genes of seed plants and to infer the ancestral functions of these genes. Key Results Type I MADS-box genes are under-represented in gymnosperms and only a minimum of two Type I MADS-box genes have been present in the most recent common ancestor (MRCA) of seed plants. In contrast, a large number of Type II MADS-box genes were found in gymnosperms. The MRCA of extant seed plants probably possessed at least 11–14 Type II MADS-box genes. In gymnosperms two duplications of Type II MADS-box genes were found, such that the MRCA of extant gymnosperms had at least 14–16 Type II MADS-box genes. Conclusions The implied ancestral set of MADS-box genes for seed plants shows simplicity for Type I MADS-box genes and remarkable complexity for Type II MADS-box genes in terms of phylogeny and putative functions. The analysis of transcriptome data reveals that gymnosperm MADS-box genes are expressed in a great variety of tissues, indicating diverse roles of MADS

  17. Generation, functional annotation and comparative analysis of black spruce (Picea mariana) ESTs: an important conifer genomic resource

    PubMed Central

    2013-01-01

    Background EST (expressed sequence tag) sequences and their annotation provide a highly valuable resource for gene discovery, genome sequence annotation, and other genomics studies that can be applied in genetics, breeding and conservation programs for non-model organisms. Conifers are long-lived plants that are ecologically and economically important globally, and have a large genome size. Black spruce (Picea mariana), is a transcontinental species of the North American boreal and temperate forests. However, there are limited transcriptomic and genomic resources for this species. The primary objective of our study was to develop a black spruce transcriptomic resource to facilitate on-going functional genomics projects related to growth and adaptation to climate change. Results We conducted bidirectional sequencing of cDNA clones from a standard cDNA library constructed from black spruce needle tissues. We obtained 4,594 high quality (2,455 5' end and 2,139 3' end) sequence reads, with an average read-length of 532 bp. Clustering and assembly of ESTs resulted in 2,731 unique sequences, consisting of 2,234 singletons and 497 contigs. Approximately two-thirds (63%) of unique sequences were functionally annotated. Genes involved in 36 molecular functions and 90 biological processes were discovered, including 24 putative transcription factors and 232 genes involved in photosynthesis. Most abundantly expressed transcripts were associated with photosynthesis, growth factors, stress and disease response, and transcription factors. A total of 216 full-length genes were identified. About 18% (493) of the transcripts were novel, representing an important addition to the Genbank EST database (dbEST). Fifty-seven di-, tri-, tetra- and penta-nucleotide simple sequence repeats were identified. Conclusions We have developed the first high quality EST resource for black spruce and identified 493 novel transcripts, which may be species-specific related to life history and

  18. Altered community flammability in Florida's Apalachicola ravines and implications for the persistence of the endangered conifer Torreya taxifolia.

    PubMed

    Mola, John M; Varner, J Morgan; Jules, Erik S; Spector, Tova

    2014-01-01

    Plant species and communities often reflect historic fire regimes via ecological and evolutionary responses to recurrent fires. Plant communities of the southeastern USA experience a wide array of fire regimes, perhaps nowhere more marked than the juxtaposition of fire-prone uplands and adjacent mesic ravines along Florida's Apalachicola River. The ravines contain many endemic and disjunct species, most notably the endangered endemic conifer Torreya taxifolia. A rapid decline in T. taxifolia over the past 60 years has been associated with widespread replacement by other tree species. To understand the changes accompanying the shift in ravine composition, we compared leaf litter flammability of nine historic and contemporary species. We measured maximum flame height, flame duration, smoldering duration, mass loss, absorptive capacity, and drying rate. Ordination and perMANOVA suggest the nine species segregated into three distinct groups: the fire-impeding T. taxifolia and Taxus floridana; an intermediate group of three deciduous angiosperms; and a mixed cluster of four flammable species. Results suggest T. taxifolia and T. floridana were fire-impeding species in these communities, while contemporary dominants burn similarly to the upslope pyric species. The increasing presence of fire-facilitating species may portend a shifting fire regime that further imperils T. taxifolia and other rare species in the formerly fire-safe ravines. PMID:25084166

  19. Virus community dynamics in the conifer pathogenic fungus Heterobasidion parviporum following an artificial introduction of a partitivirus.

    PubMed

    Vainio, Eeva J; Piri, Tuula; Hantula, Jarkko

    2013-01-01

    Viruses infecting the conifer pathogenic fungus Heterobasidion annosum sensu lato are intracellular and spread via anastomosis contacts. In the laboratory, these viruses transmit readily even between somatically incompatible isolates, but their dispersal capacity in natural conditions has not been previously studied. We introduced a mycovirus to a heavily diseased forest site by inoculating Norway spruce stumps with heartrot decay using a mycelial suspension of Heterobasidion parviporum strain RT3.49C hosting the partitivirus strain HetRV4-pa1. The Heterobasidion population at the sample plot was screened for mycoviruses prior to and after the inoculation. Based on sequence analysis, the resident H. parviporum strains harbored six different strains of the virus species Heterobasidion RNA virus 6 (HetRV6) and one strain of HetRV4 prior to the inoculation. After three growth seasons, the inoculated H. parviporum host strain was not detected, but the introduced virus had infected two resident H. parviporum genets. The presence of a preexisting HetRV6 infection did not hinder spread of the introduced partitivirus but resulted in coinfections instead. The resident HetRV6 virus population seemed to be highly stable during the incubation period, while the single indigenous HetRV4 infection was not detected after the inoculation. In laboratory infection experiments, the introduced virus could be transmitted successfully into all of the resident H. parviporum genets. This study shows for the first time transmission of a Heterobasidion virus between somatically incompatible hosts in natural conditions.

  20. Role of burning season on initial understory vegetation response to prescribed fire in a mixed conifer forest

    USGS Publications Warehouse

    Knapp, E.E.; Schwilk, D.W.; Kane, J.M.; Keeley, J.E.

    2007-01-01

    Although the majority of fires in the western United States historically occurred during the late summer or early fall when fuels were dry and plants were dormant or nearly so, early-season prescribed burns are often ignited when fuels are still moist and plants are actively growing. The purpose of this study was to determine if burn season influences postfire vegetation recovery. Replicated early-season burn, late-season burn, and unburned control units were established in a mixed conifer forest, and understory vegetation was evaluated before and after treatment. Vegetation generally recovered rapidly after prescribed burning. However, late-season burns resulted in a temporary but significant drop in cover and a decline in species richness at the 1 m 2 scale in the following year. For two of the several taxa that were negatively affected by burning, the reduction in frequency was greater after late-season than early-season burns. Early-season burns may have moderated the effect of fire by consuming less fuel and lessening the amount of soil heating. Our results suggest that, when burned under high fuel loading conditions, many plant species respond more strongly to differences in fire intensity and severity than to timing of the burn relative to stage of plant growth. ?? 2007 NRC.

  1. Uptake of Water via Branches Helps Timberline Conifers Refill Embolized Xylem in Late Winter1[C][W][OPEN

    PubMed Central

    Mayr, Stefan; Schmid, Peter; Laur, Joan; Rosner, Sabine; Charra-Vaskou, Katline; Dämon, Birgit; Hacke, Uwe G.

    2014-01-01

    Xylem embolism is a limiting factor for woody species worldwide. Conifers at the alpine timberline are exposed to drought and freeze-thaw stress during winter, which induce potentially lethal embolism. Previous studies indicated that timberline trees survive by xylem refilling. In this study on Picea abies, refilling was monitored during winter and spring seasons and analyzed in the laboratory and in situ experiments, based on hydraulic, anatomical, and histochemical methods. Refilling started in late winter, when the soil was frozen and soil water not available for the trees. Xylem embolism caused up to 86.2% ± 3.1% loss of conductivity and was correlated with the ratio of closed pits. Refilling of xylem as well as recovery in shoot conductance started in February and corresponded with starch accumulation in secondary phloem and in the mesophyll of needles, where we also observed increasing aquaporin densities in the phloem and endodermis. This indicates that active, cellular processes play a role for refilling even under winter conditions. As demonstrated by our experiments, water for refilling was thereby taken up via the branches, likely by foliar water uptake. Our results suggest that refilling is based on water shifts to embolized tracheids via intact xylem, phloem, and parenchyma, whereby aquaporins reduce resistances along the symplastic pathway and aspirated pits facilitate isolation of refilling tracheids. Refilling must be taken into account as a key process in plant hydraulics and in estimating future effects of climate change on forests and alpine tree ecosystems. PMID:24521876

  2. Conflicting selection from fire and seed predation drives fine-scaled phenotypic variation in a widespread North American conifer.

    PubMed

    Talluto, Matthew V; Benkman, Craig W

    2014-07-01

    Recent work has demonstrated that evolutionary processes shape ecological dynamics on relatively short timescales (eco-evolutionary dynamics), but demonstrating these effects at large spatial scales in natural landscapes has proven difficult. We used empirical studies and modeling to investigate how selective pressures from fire and predispersal seed predation affect the evolution of serotiny, an ecologically important trait. Serotiny is a highly heritable key reproductive trait in Rocky Mountain lodgepole pine (Pinus contorta subsp. latifolia), a conifer that dominates millions of hectares in western North America. In these forests, the frequency of serotiny determines postfire seedling density with corresponding community- and ecosystem-level effects. We found that serotinous individuals have a selective advantage at high fire frequencies and low predation pressure; however, very high seed predation shifted the selective advantage to nonserotinous individuals even at high fire frequencies. Simulation modeling suggests that spatial variation in the frequency of serotiny results from heterogeneity in these two selective agents. These results, combined with previous findings showing a negative association between the density of seed predators and the frequency of serotiny at both landscape and continental scales, demonstrate that contemporary patterns in serotiny reflect an evolutionary response to conflicting selection pressures from fire and seed predation. Thus, we show that variation in the frequency of a heritable polygenic trait depends on spatial variation in two dominant selective agents, and, importantly, the effects of the local trait variation propagate with profound consequences to the structure and function of communities and ecosystems across a large landscape. PMID:24979772

  3. Paleoecology of late-glacial terrestrial deposits with in situ conifers from the submerged continental shelf of western canada

    NASA Astrophysics Data System (ADS)

    Lacourse, Terri; Mathewes, Rolf W.; Fedje, Daryl W.

    2003-09-01

    Extensive portions of the continental shelf off the coast of British Columbia were subaerially exposed during Late Wisconsinan deglaciation due to lowering of relative sea level by as much as 150 m. Paleoecological analyses were conducted at two sites on the emergent continental shelf where terrestrial surfaces with in situ conifers are preserved. The woody plant remains confirm that, during the latest period of subaerial exposure, terrestrial vegetation was established on the continental shelf. Microscopic identification of fossil wood, and analyses of pollen and plant macrofossils from the associated paleosols and overlying shallow pond sediments indicate that productive Pinus contorta-dominated communities with abundant Alnus crispa and ferns grew on the shelf adjacent to and on the Queen Charlotte Islands around 12,200 14C yr B.P. Dwarf shrubs including Salix and Empetrum, and herbaceous plants such as Heracleum lanatum and Hippuris vulgaris, were also important components of the shelf vegetation. Near northern Vancouver Island, mixed coniferous forests dominated by Pinus contorta with Picea, Tsuga spp., Alnus spp., and ferns occupied the shelf at 10,500 14C yr B.P.

  4. The periodic wetting of leaves enhances water relations and growth of the long-lived conifer Araucaria angustifolia.

    PubMed

    Cassana, F F; Dillenburg, L R

    2013-01-01

    The importance of foliar absorption of water and atmospheric solutes in conifers was recognised in the 1970s, and the importance of fog as a water source in forest environments has been recently demonstrated. Araucaria angustifolia (Araucariaceae) is an emergent tree species that grows in montane forests of southern Brazil, where rainfall and fog are frequent events, leading to frequent wetting of the leaves. Despite anatomical evidence in favour of leaf water absorption, there is no information on the existence and physiological significance of a such process. In this study, we test the hypothesis that the use of atmospheric water by leaves takes place and is physiologically relevant for the species, by comparing growth, water relations and nutritional status between plants grown under two conditions of soil water (well-watered and water-stressed plants) and three types of leaf spraying (none, water and nutrient solution spray). Leaf spraying had a greater effect in improving plant water relations when plants were under water stress. Plant growth was more responsive to water available to the leaves than to the roots, and was equally increased by both types of leaf spraying, with no interaction with soil water status. Spraying leaves with nutrient solution increased shoot ramification and raised the concentrations of N, P, K, Zn, Cu and Fe in the roots. Our results provide strong indications that water and nutrients are indeed absorbed by leaves of A. angustifolia, and that this process might be as important as water uptake by its roots.

  5. Primer Sets Developed To Amplify Conserved Genes from Filamentous Ascomycetes Are Useful in Differentiating Fusarium Species Associated with Conifers

    PubMed Central

    Donaldson, G. C.; Ball, L. A.; Axelrood, P. E.; Glass, N. L.

    1995-01-01

    We examined the usefulness of primer sets designed to amplify introns within conserved genes in filamentous ascomycetes to differentiate 35 isolates representing six different species of Fusarium commonly found in association with conifer seedlings. We analyzed restriction fragment length polymorphisms (RFLP) in five amplified PCR products from each Fusarium isolate. The primers used in this study were constructed on the basis of sequence information from the H3, H4, and (beta)-tubulin genes in Neurospora crassa. Primers previously developed for the intergenic transcribed spacer region of the ribosomal DNA were also used. The degree of interspecific polymorphism observed in the PCR products from the six Fusarium species allowed differentiation by a limited number of amplifications and restriction endonuclease digestions. The level of intraspecific RFLP variation in the five PCR products was low in both Fusarium proliferatum and F. avenaceum but was high in a population sample of F. oxysporum isolates. Clustering of the 35 isolates by statistical analyses gave similar dendrograms for H3, H4, and (beta)-tubulin RFLP analysis, but a dendrogram produced by intergenic transcribed spacer analysis varied in the placement of some F. oxysporum isolates. PMID:16534991

  6. DNA barcoding reveals a mysterious high species diversity of conifer-feeding aphids in the mountains of southwest China.

    PubMed

    Chen, Rui; Jiang, Li-Yun; Chen, Jing; Qiao, Ge-Xia

    2016-02-03

    The mountains of southwest China are one of the hot spots of biodiversity in the world. However, the high-altitude fauna that inhabit these mountains remain a mystery. In this study, the species diversity of the aphids of the genus Cinara from the high-altitude coniferous forests was first assessed, and then the processes and the mechanisms of speciation were discussed. Three hundreds and four aphid samples that contained 3040 individuals were collected during fourteen field surveys. The molecular clusters derived from the DNA barcodes were used to explore the species diversity. Notably, the aphid alpha-diversity was high, with as many as 94 candidate species, and furthermore, 86.2% of the species collected had not been previously recorded. The centers of aphid species richness corresponded to the distributional pattern of the diversity of the host conifer plant species. The divergence time revealed that following the uplift of the Qinghai-Tibetan Plateau during the Pleistocene, the changes in the climate, ecology and host habitats were likely the most important factors that drove the rapid process of evolutionary radiation in the aphids. Our findings revealed the high species diversity of the aphids with DNA barcoding.

  7. DNA barcoding reveals a mysterious high species diversity of conifer-feeding aphids in the mountains of southwest China

    PubMed Central

    Chen, Rui; Jiang, Li-Yun; Chen, Jing; Qiao, Ge-Xia

    2016-01-01

    The mountains of southwest China are one of the hot spots of biodiversity in the world. However, the high-altitude fauna that inhabit these mountains remain a mystery. In this study, the species diversity of the aphids of the genus Cinara from the high-altitude coniferous forests was first assessed, and then the processes and the mechanisms of speciation were discussed. Three hundreds and four aphid samples that contained 3040 individuals were collected during fourteen field surveys. The molecular clusters derived from the DNA barcodes were used to explore the species diversity. Notably, the aphid alpha-diversity was high, with as many as 94 candidate species, and furthermore, 86.2% of the species collected had not been previously recorded. The centers of aphid species richness corresponded to the distributional pattern of the diversity of the host conifer plant species. The divergence time revealed that following the uplift of the Qinghai-Tibetan Plateau during the Pleistocene, the changes in the climate, ecology and host habitats were likely the most important factors that drove the rapid process of evolutionary radiation in the aphids. Our findings revealed the high species diversity of the aphids with DNA barcoding. PMID:26838797

  8. The periodic wetting of leaves enhances water relations and growth of the long-lived conifer Araucaria angustifolia.

    PubMed

    Cassana, F F; Dillenburg, L R

    2013-01-01

    The importance of foliar absorption of water and atmospheric solutes in conifers was recognised in the 1970s, and the importance of fog as a water source in forest environments has been recently demonstrated. Araucaria angustifolia (Araucariaceae) is an emergent tree species that grows in montane forests of southern Brazil, where rainfall and fog are frequent events, leading to frequent wetting of the leaves. Despite anatomical evidence in favour of leaf water absorption, there is no information on the existence and physiological significance of a such process. In this study, we test the hypothesis that the use of atmospheric water by leaves takes place and is physiologically relevant for the species, by comparing growth, water relations and nutritional status between plants grown under two conditions of soil water (well-watered and water-stressed plants) and three types of leaf spraying (none, water and nutrient solution spray). Leaf spraying had a greater effect in improving plant water relations when plants were under water stress. Plant growth was more responsive to water available to the leaves than to the roots, and was equally increased by both types of leaf spraying, with no interaction with soil water status. Spraying leaves with nutrient solution increased shoot ramification and raised the concentrations of N, P, K, Zn, Cu and Fe in the roots. Our results provide strong indications that water and nutrients are indeed absorbed by leaves of A. angustifolia, and that this process might be as important as water uptake by its roots. PMID:22672733

  9. Altered Community Flammability in Florida’s Apalachicola Ravines and Implications for the Persistence of the Endangered Conifer Torreya taxifolia

    PubMed Central

    Mola, John M.; Varner, J. Morgan; Jules, Erik S.; Spector, Tova

    2014-01-01

    Plant species and communities often reflect historic fire regimes via ecological and evolutionary responses to recurrent fires. Plant communities of the southeastern USA experience a wide array of fire regimes, perhaps nowhere more marked than the juxtaposition of fire-prone uplands and adjacent mesic ravines along Florida’s Apalachicola River. The ravines contain many endemic and disjunct species, most notably the endangered endemic conifer Torreya taxifolia. A rapid decline in T. taxifolia over the past 60 years has been associated with widespread replacement by other tree species. To understand the changes accompanying the shift in ravine composition, we compared leaf litter flammability of nine historic and contemporary species. We measured maximum flame height, flame duration, smoldering duration, mass loss, absorptive capacity, and drying rate. Ordination and perMANOVA suggest the nine species segregated into three distinct groups: the fire-impeding T. taxifolia and Taxus floridana; an intermediate group of three deciduous angiosperms; and a mixed cluster of four flammable species. Results suggest T. taxifolia and T. floridana were fire-impeding species in these communities, while contemporary dominants burn similarly to the upslope pyric species. The increasing presence of fire-facilitating species may portend a shifting fire regime that further imperils T. taxifolia and other rare species in the formerly fire-safe ravines. PMID:25084166

  10. Late Holocene geomorphic record of fire in ponderosa pine and mixed-conifer forests, Kendrick Mountain, northern Arizona, USA

    USGS Publications Warehouse

    Jenkins, S.E.; Hull, Sieg C.; Anderson, D.E.; Kaufman, D.S.; Pearthree, P.A.

    2011-01-01

    Long-term fire history reconstructions enhance our understanding of fire behaviour and associated geomorphic hazards in forested ecosystems. We used 14C ages on charcoal from fire-induced debris-flow deposits to date prehistoric fires on Kendrick Mountain, northern Arizona, USA. Fire-related debris-flow sedimentation dominates Holocene fan deposition in the study area. Radiocarbon ages indicate that stand-replacing fire has been an important phenomenon in late Holocene ponderosa pine (Pinus ponderosa) and ponderosa pine-mixed conifer forests on steep slopes. Fires have occurred on centennial scales during this period, although temporal hiatuses between recorded fires vary widely and appear to have decreased during the past 2000 years. Steep slopes and complex terrain may be responsible for localised crown fire behaviour through preheating by vertical fuel arrangement and accumulation of excessive fuels. Holocene wildfire-induced debris flow events occurred without a clear relationship to regional climatic shifts (decadal to millennial), suggesting that interannual moisture variability may determine fire year. Fire-debris flow sequences are recorded when (1) sufficient time has passed (centuries) to accumulate fuels; and (2) stored sediment is available to support debris flows. The frequency of reconstructed debris flows should be considered a minimum for severe events in the study area, as fuel production may outpace sediment storage. ?? IAWF 2011.

  11. Static and dynamic bending has minor effects on xylem hydraulics of conifer branches (Picea abies, Pinus sylvestris).

    PubMed

    Mayr, Stefan; Bertel, Clara; Dämon, Birgit; Beikircher, Barbara

    2014-09-01

    The xylem hydraulic efficiency and safety is usually measured on mechanically unstressed samples, although trees may be exposed to combined hydraulic and mechanical stress in the field. We analysed changes in hydraulic conductivity and vulnerability to drought-induced embolism during static bending of Picea abies and Pinus sylvestris branches as well as the effect of dynamic bending on the vulnerability. We hypothesized this mechanical stress to substantially impair xylem hydraulics. Intense static bending caused an only small decrease in hydraulic conductance (-19.5 ± 2.4% in P. abies) but no shift in vulnerability thresholds. Dynamic bending caused a 0.4 and 0.8 MPa decrease of the water potential at 50 and 88% loss of conductivity in P. sylvestris, but did not affect vulnerability thresholds in P. abies. With respect to applied extreme bending radii, effects on plant hydraulics were surprisingly small and are thus probably of minor eco-physiological importance. More importantly, results indicate that available xylem hydraulic analyses (of conifers) sufficiently reflect plant hydraulics under field conditions. PMID:24697679

  12. Establishing a Wild, Ex Situ Population of a Critically Endangered Shade-Tolerant Rainforest Conifer: A Translocation Experiment

    PubMed Central

    Zimmer, Heidi C.; Offord, Catherine A.; Auld, Tony D.; Baker, Patrick J.

    2016-01-01

    Translocation can reduce extinction risk by increasing population size and geographic range, and is increasingly being used in the management of rare and threatened plant species. A critical determinant of successful plant establishment is light environment. Wollemia nobilis (Wollemi pine) is a critically endangered conifer, with a wild population of 83 mature trees and a highly restricted distribution of less than 10 km2. We used under-planting to establish a population of W. nobilis in a new rainforest site. Because its optimal establishment conditions were unknown, we conducted an experimental translocation, planting in a range of different light conditions from deeply shaded to high light gaps. Two years after the experimental translocation, 85% of plants had survived. There were two distinct responses: very high survival (94%) but very low growth, and lower survival (69%) and higher growth, associated with initial plant condition. Overall survival of translocated W. nobilis was strongly increased in planting sites with higher light, in contrast to previous studies demonstrating long-term survival of wild W. nobilis juveniles in deep shade. Translocation by under-planting may be useful in establishing new populations of shade-tolerant plant species, not least by utilizing the range of light conditions that occur in forest understories. PMID:27403527

  13. Climatic influences on wood anatomy and tree-ring features of Great Basin conifers at a new mountain observatory1

    PubMed Central

    Ziaco, Emanuele; Biondi, Franco; Rossi, Sergio; Deslauriers, Annie

    2014-01-01

    • Premise of the study: A network of mountain observing stations has been installed in the Great Basin of North America. NevCAN (Nevada Climate-ecohydrological Assessment Network), which spans a latitudinal range of 2.5° and two elevation ranges of about 2000 m each, enabled us to investigate tree growth in relation to climate. • Methods: We analyzed wood anatomy and tree-ring characteristics of four conifer species in response to different levels of water availability by comparing a low- and a high-elevation population. Chronologies of earlywood and latewood widths, as well as cellular parameters, were developed from the year 2000 to 2012. • Results: At the southern (drier and warmer) sites, Pinus monophylla had smaller cell lumen, tracheid diameter, and cell wall thickness. Pinus monophylla and P. flexilis showed bigger cellular elements at the higher elevations, whereas the opposite pattern was found in Picea engelmannii and Pinus longaeva. When all species and sites were pooled together, stem diameter was positively related with earlywood anatomical parameters. • Discussion: We have provided a glimpse of the applications that NevCAN, as a new scientific tool, could allow in the general field of botany. In particular, we were able to investigate how differences in water stress related to elevation lead to changes in xylem anatomy. PMID:25309838

  14. Whole genome duplication in coast redwood (Sequoia sempervirens) and its implications for explaining the rarity of polyploidy in conifers.

    PubMed

    Scott, Alison Dawn; Stenz, Noah W M; Ingvarsson, Pär K; Baum, David A

    2016-07-01

    Polyploidy is common and an important evolutionary factor in most land plant lineages, but it is rare in gymnosperms. Coast redwood (Sequoia sempervirens) is one of just two polyploid conifer species and the only hexaploid. Evidence from fossil guard cell size suggests that polyploidy in Sequoia dates to the Eocene. Numerous hypotheses about the mechanism of polyploidy and parental genome donors have been proposed, based primarily on morphological and cytological data, but it remains unclear how Sequoia became polyploid and why this lineage overcame an apparent gymnosperm barrier to whole-genome duplication (WGD). We sequenced transcriptomes and used phylogenetic inference, Bayesian concordance analysis and paralog age distributions to resolve relationships among gene copies in hexaploid coast redwood and close relatives. Our data show that hexaploidy in coast redwood is best explained by autopolyploidy or, if there was allopolyploidy, it happened within the Californian redwood clade. We found that duplicate genes have more similar sequences than expected, given the age of the inferred polyploidization. Conflict between molecular and fossil estimates of WGD can be explained if diploidization occurred very slowly following polyploidization. We extrapolate from this to suggest that the rarity of polyploidy in gymnosperms may be due to slow diploidization in this clade.

  15. Relevance of the Sea Sand Disruption Method (SSDM) for the biometrical differentiation of the essential-oil composition from conifers.

    PubMed

    Dawidowicz, Andrzej L; Czapczyńska, Natalia B; Wianowska, Dorota

    2013-02-01

    Sea Sand Disruption Method (SSDM) is a simple and cheap sample-preparation procedure allowing the reduction of organic solvent consumption, exclusion of sample component degradation, improvement of extraction efficiency and selectivity, and elimination of additional sample clean-up and pre-concentration step before chromatographic analysis. This article deals with the possibility of SSDM application for the differentiation of essential-oils components occurring in the Scots pine (Pinus sylvestris L.) and cypress (Cupressus sempervirens L.) needles from Madrid (Spain), Laganas (Zakhyntos, Greece), Cala Morell (Menorca, Spain), Lublin (Poland), Helsinki (Finland), and Oradea (Romania). The SSDM results are related to the analogous - obtained applying two other sample preparation methods - steam distillation and Pressurized Liquid Extraction (PLE). The results presented established that the total amount and the composition of essential-oil components revealed by SSDM are equivalent or higher than those obtained by one of the most effective extraction technique, PLE. Moreover, SSDM seems to provide the most representative profile of all essential-oil components as no heat is applied. Thus, this environmentally friendly method is suggested to be used as the main extraction procedure for the differentiation of essential-oil components in conifers for scientific and industrial purposes. PMID:23418171

  16. Conflicting selection from fire and seed predation drives fine-scaled phenotypic variation in a widespread North American conifer

    PubMed Central

    Talluto, Matthew V.; Benkman, Craig W.

    2014-01-01

    Recent work has demonstrated that evolutionary processes shape ecological dynamics on relatively short timescales (eco-evolutionary dynamics), but demonstrating these effects at large spatial scales in natural landscapes has proven difficult. We used empirical studies and modeling to investigate how selective pressures from fire and predispersal seed predation affect the evolution of serotiny, an ecologically important trait. Serotiny is a highly heritable key reproductive trait in Rocky Mountain lodgepole pine (Pinus contorta subsp. latifolia), a conifer that dominates millions of hectares in western North America. In these forests, the frequency of serotiny determines postfire seedling density with corresponding community- and ecosystem-level effects. We found that serotinous individuals have a selective advantage at high fire frequencies and low predation pressure; however, very high seed predation shifted the selective advantage to nonserotinous individuals even at high fire frequencies. Simulation modeling suggests that spatial variation in the frequency of serotiny results from heterogeneity in these two selective agents. These results, combined with previous findings showing a negative association between the density of seed predators and the frequency of serotiny at both landscape and continental scales, demonstrate that contemporary patterns in serotiny reflect an evolutionary response to conflicting selection pressures from fire and seed predation. Thus, we show that variation in the frequency of a heritable polygenic trait depends on spatial variation in two dominant selective agents, and, importantly, the effects of the local trait variation propagate with profound consequences to the structure and function of communities and ecosystems across a large landscape. PMID:24979772

  17. Relevance of the Sea Sand Disruption Method (SSDM) for the biometrical differentiation of the essential-oil composition from conifers.

    PubMed

    Dawidowicz, Andrzej L; Czapczyńska, Natalia B; Wianowska, Dorota

    2013-02-01

    Sea Sand Disruption Method (SSDM) is a simple and cheap sample-preparation procedure allowing the reduction of organic solvent consumption, exclusion of sample component degradation, improvement of extraction efficiency and selectivity, and elimination of additional sample clean-up and pre-concentration step before chromatographic analysis. This article deals with the possibility of SSDM application for the differentiation of essential-oils components occurring in the Scots pine (Pinus sylvestris L.) and cypress (Cupressus sempervirens L.) needles from Madrid (Spain), Laganas (Zakhyntos, Greece), Cala Morell (Menorca, Spain), Lublin (Poland), Helsinki (Finland), and Oradea (Romania). The SSDM results are related to the analogous - obtained applying two other sample preparation methods - steam distillation and Pressurized Liquid Extraction (PLE). The results presented established that the total amount and the composition of essential-oil components revealed by SSDM are equivalent or higher than those obtained by one of the most effective extraction technique, PLE. Moreover, SSDM seems to provide the most representative profile of all essential-oil components as no heat is applied. Thus, this environmentally friendly method is suggested to be used as the main extraction procedure for the differentiation of essential-oil components in conifers for scientific and industrial purposes.

  18. The ectomycorrhizal community of conifer stands on peat soils 12 years after fertilization with wood ash.

    PubMed

    Klavina, Darta; Pennanen, Taina; Gaitnieks, Talis; Velmala, Sannakajsa; Lazdins, Andis; Lazdina, Dagnija; Menkis, Audrius

    2016-02-01

    We studied long-term effects of fertilization with wood ash on biomass, vitality and mycorrhizal colonization of fine roots in three conifer forest stands growing in Vacciniosa turf. mel. (V), Myrtillosa turf. mel. (M) and Myrtillosa turf. mel./Caricoso-phragmitosa (MC) forest types on peat soils. Fertilization trials amounting 5 kg/m(2) of wood ash were established 12 years prior to this study. A total of 63 soil samples with roots were collected and analysed. Ectomycorrhizal (ECM) fungi in roots were identified by morphotyping and sequencing of the fungal internal transcribed spacer (ITS) region. In all forest types, fine root biomass was higher in fertilized plots than in control plots. In M forest type, proportion of living fine roots was greater in fertilized plots than in control plots, while in V and MC, the result was opposite. Fifty ECM species were identified, of which eight were common to both fertilized and control plots. Species richness and Shannon diversity index were generally higher in fertilized plots than in control plots. The most common species in fertilized plots were Amphinema byssoides (17.8%) and Tuber cf. anniae (12.2%), while in control plots, it was Tylospora asterophora (18.5%) and Lactarius tabidus (20.3%). Our results showed that forest fertilization with wood ash has long-lasting effect on diversity and composition of ECM fungal communities. PMID:26208815

  19. Climate, not Aboriginal landscape burning, controlled the historical demography and distribution of fire-sensitive conifer populations across Australia.

    PubMed

    Sakaguchi, Shota; Bowman, David M J S; Prior, Lynda D; Crisp, Michael D; Linde, Celeste C; Tsumura, Yoshihiko; Isagi, Yuji

    2013-12-22

    Climate and fire are the key environmental factors that shape the distribution and demography of plant populations in Australia. Because of limited palaeoecological records in this arid continent, however, it is unclear as to which factor impacted vegetation more strongly, and what were the roles of fire regime changes owing to human activity and megafaunal extinction (since ca 50 kya). To address these questions, we analysed historical genetic, demographic and distributional changes in a widespread conifer species complex that paradoxically grows in fire-prone regions, yet is very sensitive to fire. Genetic demographic analysis showed that the arid populations experienced strong bottlenecks, consistent with range contractions during the Last Glacial Maximum (ca 20 kya) predicted by species distribution models. In southern temperate regions, the population sizes were estimated to have been mostly stable, followed by some expansion coinciding with climate amelioration at the end of the last glacial period. By contrast, in the flammable tropical savannahs, where fire risk is the highest, demographic analysis failed to detect significant population bottlenecks. Collectively, these results suggest that the impact of climate change overwhelmed any modifications to fire regimes by Aboriginal landscape burning and megafaunal extinction, a finding that probably also applies to other fire-prone vegetation across Australia.

  20. The influence of hydrologic conditions and peat oxia on the phosphorus and nitrogen dynamics of a conifer swamp

    NASA Astrophysics Data System (ADS)

    Devito, Kevin J.; Dillon, Peter J.

    1993-08-01

    A mass balance approach was used to determine the factors influencing phosphorus and nitrogen dynamics in wetlands common to headwater catchments of the Precambrian Shield. The relationships of runoff, water level, water temperature, and anoxia to the annual and seasonal total phosphorus (TP) and total nitrogen (TN) retentions of a headwater Sphagnum-conifer swamp during 1987-1988 were examined. Annual retentions of TP (4%) and TN (10%) were low in the swamp. On an annual basis, inputs exceeded outputs of total reactive P, NO3-N, and NH4-N and outputs exceeded inputs of total unreactive P and total organic N. Seasonal trends in P and N retention were inversely correlated with runoff. Positive monthly retention coincided with low runoff and increased biotic assimilation during the growing season. Water table drawdown during the summer was associated with peat aeration and increased levels of P and N in surface and pore water. High levels of P and N in the swamp surface water during the fall and winter were coupled with increased runoff, saturated overland flow, and potentially low biotic assimilation resulting in a net release of TP and TN. Large flow through of waterborne inputs and flushing of regenerated P and N occurred during peak snowmelt runoff resulting in low annual retention.

  1. Climate, not Aboriginal landscape burning, controlled the historical demography and distribution of fire-sensitive conifer populations across Australia

    PubMed Central

    Sakaguchi, Shota; Bowman, David M. J. S.; Prior, Lynda D.; Crisp, Michael D.; Linde, Celeste C.; Tsumura, Yoshihiko; Isagi, Yuji

    2013-01-01

    Climate and fire are the key environmental factors that shape the distribution and demography of plant populations in Australia. Because of limited palaeoecological records in this arid continent, however, it is unclear as to which factor impacted vegetation more strongly, and what were the roles of fire regime changes owing to human activity and megafaunal extinction (since ca 50 kya). To address these questions, we analysed historical genetic, demographic and distributional changes in a widespread conifer species complex that paradoxically grows in fire-prone regions, yet is very sensitive to fire. Genetic demographic analysis showed that the arid populations experienced strong bottlenecks, consistent with range contractions during the Last Glacial Maximum (ca 20 kya) predicted by species distribution models. In southern temperate regions, the population sizes were estimated to have been mostly stable, followed by some expansion coinciding with climate amelioration at the end of the last glacial period. By contrast, in the flammable tropical savannahs, where fire risk is the highest, demographic analysis failed to detect significant population bottlenecks. Collectively, these results suggest that the impact of climate change overwhelmed any modifications to fire regimes by Aboriginal landscape burning and megafaunal extinction, a finding that probably also applies to other fire-prone vegetation across Australia. PMID:24174110

  2. Establishing a Wild, Ex Situ Population of a Critically Endangered Shade-Tolerant Rainforest Conifer: A Translocation Experiment.

    PubMed

    Zimmer, Heidi C; Offord, Catherine A; Auld, Tony D; Baker, Patrick J

    2016-01-01

    Translocation can reduce extinction risk by increasing population size and geographic range, and is increasingly being used in the management of rare and threatened plant species. A critical determinant of successful plant establishment is light environment. Wollemia nobilis (Wollemi pine) is a critically endangered conifer, with a wild population of 83 mature trees and a highly restricted distribution of less than 10 km2. We used under-planting to establish a population of W. nobilis in a new rainforest site. Because its optimal establishment conditions were unknown, we conducted an experimental translocation, planting in a range of different light conditions from deeply shaded to high light gaps. Two years after the experimental translocation, 85% of plants had survived. There were two distinct responses: very high survival (94%) but very low growth, and lower survival (69%) and higher growth, associated with initial plant condition. Overall survival of translocated W. nobilis was strongly increased in planting sites with higher light, in contrast to previous studies demonstrating long-term survival of wild W. nobilis juveniles in deep shade. Translocation by under-planting may be useful in establishing new populations of shade-tolerant plant species, not least by utilizing the range of light conditions that occur in forest understories. PMID:27403527

  3. Static and dynamic bending has minor effects on xylem hydraulics of conifer branches (Picea abies, Pinus sylvestris)

    PubMed Central

    Mayr, Stefan; Bertel, Clara; Dämon, Birgit; Beikircher, Barbara

    2014-01-01

    The xylem hydraulic efficiency and safety is usually measured on mechanically unstressed samples, although trees may be exposed to combined hydraulic and mechanical stress in the field. We analysed changes in hydraulic conductivity and vulnerability to drought-induced embolism during static bending of Picea abies and Pinus sylvestris branches as well as the effect of dynamic bending on the vulnerability. We hypothesized this mechanical stress to substantially impair xylem hydraulics. Intense static bending caused an only small decrease in hydraulic conductance (−19.5 ± 2.4% in P. abies) but no shift in vulnerability thresholds. Dynamic bending caused a 0.4 and 0.8 MPa decrease of the water potential at 50 and 88% loss of conductivity in P. sylvestris, but did not affect vulnerability thresholds in P. abies. With respect to applied extreme bending radii, effects on plant hydraulics were surprisingly small and are thus probably of minor eco-physiological importance. More importantly, results indicate that available xylem hydraulic analyses (of conifers) sufficiently reflect plant hydraulics under field conditions. PMID:24697679

  4. Whole genome duplication in coast redwood (Sequoia sempervirens) and its implications for explaining the rarity of polyploidy in conifers.

    PubMed

    Scott, Alison Dawn; Stenz, Noah W M; Ingvarsson, Pär K; Baum, David A

    2016-07-01

    Polyploidy is common and an important evolutionary factor in most land plant lineages, but it is rare in gymnosperms. Coast redwood (Sequoia sempervirens) is one of just two polyploid conifer species and the only hexaploid. Evidence from fossil guard cell size suggests that polyploidy in Sequoia dates to the Eocene. Numerous hypotheses about the mechanism of polyploidy and parental genome donors have been proposed, based primarily on morphological and cytological data, but it remains unclear how Sequoia became polyploid and why this lineage overcame an apparent gymnosperm barrier to whole-genome duplication (WGD). We sequenced transcriptomes and used phylogenetic inference, Bayesian concordance analysis and paralog age distributions to resolve relationships among gene copies in hexaploid coast redwood and close relatives. Our data show that hexaploidy in coast redwood is best explained by autopolyploidy or, if there was allopolyploidy, it happened within the Californian redwood clade. We found that duplicate genes have more similar sequences than expected, given the age of the inferred polyploidization. Conflict between molecular and fossil estimates of WGD can be explained if diploidization occurred very slowly following polyploidization. We extrapolate from this to suggest that the rarity of polyploidy in gymnosperms may be due to slow diploidization in this clade. PMID:26996245

  5. Long-term effects of prescribed fire on mixed conifer forest structure in the Sierra Nevada, California

    USGS Publications Warehouse

    van Mantgem, Phillip J.; Stephenson, Nathan L.; Knapp, Eric; Keeley, Jon E.

    2011-01-01

    The capacity of prescribed fire to restore forest conditions is often judged by changes in forest structure within a few years following burning. However, prescribed fire might have longer-term effects on forest structure, potentially changing treatment assessments. We examined annual changes in forest structure in five 1 ha old-growth plots immediately before prescribed fire and up to eight years after fire at Sequoia National Park, California. Fire-induced declines in stem density (67% average decrease at eight years post-fire) were nonlinear, taking up to eight years to reach a presumed asymptote. Declines in live stem biomass were also nonlinear, but smaller in magnitude (32% average decrease at eight years post-fire) as most large trees survived the fires. The preferential survival of large trees following fire resulted in significant shifts in stem diameter distributions. Mortality rates remained significantly above background rates up to six years after the fires. Prescribed fire did not have a large influence on the representation of dominant species. Fire-caused mortality appeared to be spatially random, and therefore did not generally alter heterogeneous tree spatial patterns. Our results suggest that prescribed fire can bring about substantial changes to forest structure in old-growth mixed conifer forests in the Sierra Nevada, but that long-term observations are needed to fully describe some measures of fire effects.

  6. Establishing a Wild, Ex Situ Population of a Critically Endangered Shade-Tolerant Rainforest Conifer: A Translocation Experiment.

    PubMed

    Zimmer, Heidi C; Offord, Catherine A; Auld, Tony D; Baker, Patrick J

    2016-01-01

    Translocation can reduce extinction risk by increasing population size and geographic range, and is increasingly being used in the management of rare and threatened plant species. A critical determinant of successful plant establishment is light environment. Wollemia nobilis (Wollemi pine) is a critically endangered conifer, with a wild population of 83 mature trees and a highly restricted distribution of less than 10 km2. We used under-planting to establish a population of W. nobilis in a new rainforest site. Because its optimal establishment conditions were unknown, we conducted an experimental translocation, planting in a range of different light conditions from deeply shaded to high light gaps. Two years after the experimental translocation, 85% of plants had survived. There were two distinct responses: very high survival (94%) but very low growth, and lower survival (69%) and higher growth, associated with initial plant condition. Overall survival of translocated W. nobilis was strongly increased in planting sites with higher light, in contrast to previous studies demonstrating long-term survival of wild W. nobilis juveniles in deep shade. Translocation by under-planting may be useful in establishing new populations of shade-tolerant plant species, not least by utilizing the range of light conditions that occur in forest understories.

  7. Altered community flammability in Florida's Apalachicola ravines and implications for the persistence of the endangered conifer Torreya taxifolia.

    PubMed

    Mola, John M; Varner, J Morgan; Jules, Erik S; Spector, Tova

    2014-01-01

    Plant species and communities often reflect historic fire regimes via ecological and evolutionary responses to recurrent fires. Plant communities of the southeastern USA experience a wide array of fire regimes, perhaps nowhere more marked than the juxtaposition of fire-prone uplands and adjacent mesic ravines along Florida's Apalachicola River. The ravines contain many endemic and disjunct species, most notably the endangered endemic conifer Torreya taxifolia. A rapid decline in T. taxifolia over the past 60 years has been associated with widespread replacement by other tree species. To understand the changes accompanying the shift in ravine composition, we compared leaf litter flammability of nine historic and contemporary species. We measured maximum flame height, flame duration, smoldering duration, mass loss, absorptive capacity, and drying rate. Ordination and perMANOVA suggest the nine species segregated into three distinct groups: the fire-impeding T. taxifolia and Taxus floridana; an intermediate group of three deciduous angiosperms; and a mixed cluster of four flammable species. Results suggest T. taxifolia and T. floridana were fire-impeding species in these communities, while contemporary dominants burn similarly to the upslope pyric species. The increasing presence of fire-facilitating species may portend a shifting fire regime that further imperils T. taxifolia and other rare species in the formerly fire-safe ravines.

  8. [Classification method of deciduous-conifer mixed forest in jilin province based on GIS-TM remote sensing image].

    PubMed

    Wang, Lihai; Zhao, Zhengyong; Yang, Qi

    2006-04-01

    To improve the accuracy of automatic classification and identification of TM remote sensing images in forest area, an expert system for automatically classifying and identifying deciduous-conifer mixed forest was built up, based on the GIS technique, quantitative analysis on the internal relations between geographic factors such as DEM and slope aspect and environment factors like soil type, and qualitative analysis on the spectrum information and preclassification information of sensing images, aimed to build a classification knowledge system. Taking the TM remote sensing image of Wangqing Forest Bureau in Jilin Province as an example, the study showed that this expert system could obviously reduce the influence of mixed pixel and terrain shadow. The classification precision of this system was increased by 14.22%, compared with that of Iterative Self-Organizing Data Analysis Techniques Algorithm (ISODATA) unsupervised classification, and the Kappa index was 0.7556, which could help to classify needle, deciduous and mixed forests. Introducing GIS data into the expert system could also solve the problem that TM remote sensing image could not do, due to the loss of correct spectrum value in cloudy and shady area.

  9. The ectomycorrhizal community of conifer stands on peat soils 12 years after fertilization with wood ash.

    PubMed

    Klavina, Darta; Pennanen, Taina; Gaitnieks, Talis; Velmala, Sannakajsa; Lazdins, Andis; Lazdina, Dagnija; Menkis, Audrius

    2016-02-01

    We studied long-term effects of fertilization with wood ash on biomass, vitality and mycorrhizal colonization of fine roots in three conifer forest stands growing in Vacciniosa turf. mel. (V), Myrtillosa turf. mel. (M) and Myrtillosa turf. mel./Caricoso-phragmitosa (MC) forest types on peat soils. Fertilization trials amounting 5 kg/m(2) of wood ash were established 12 years prior to this study. A total of 63 soil samples with roots were collected and analysed. Ectomycorrhizal (ECM) fungi in roots were identified by morphotyping and sequencing of the fungal internal transcribed spacer (ITS) region. In all forest types, fine root biomass was higher in fertilized plots than in control plots. In M forest type, proportion of living fine roots was greater in fertilized plots than in control plots, while in V and MC, the result was opposite. Fifty ECM species were identified, of which eight were common to both fertilized and control plots. Species richness and Shannon diversity index were generally higher in fertilized plots than in control plots. The most common species in fertilized plots were Amphinema byssoides (17.8%) and Tuber cf. anniae (12.2%), while in control plots, it was Tylospora asterophora (18.5%) and Lactarius tabidus (20.3%). Our results showed that forest fertilization with wood ash has long-lasting effect on diversity and composition of ECM fungal communities.

  10. Why Seedlings Die: Linking Carbon and Water Limitations to Mechanisms of Mortality During Establishment in Conifer Seedlings

    NASA Astrophysics Data System (ADS)

    Reinhardt, K.; Germino, M. J.; Kueppers, L. M.; Mitton, J.; Castanha, C.

    2012-12-01

    BACKGROUND Recent ecophysiological studies aimed at explaining adult tree mortality during drought have examined the carbon (C)-exhaustion compared to the hydraulic-failure hypotheses for death. Prolonged drought leads to durations of stomatal closure (and thus limited C gain), which could result in long periods of negative C balance and fatal reductions in whole-plant C reserves (i.e., available non-structural carbohydrates ["NSC"]). Alternatively, C reserves may not decrease much but could become increasingly inaccessible to sink tissues in long dry-periods due to impediments to translocation of photosynthate (e.g., through disruption of hydrostatic pressure flow in phloem). As C reserves decline or become inaccessible, continued maintenance respiration has been hypothesized to lead to exhaustion of NSC after extended durations of drought, especially in isohydric plant species. On the other hand, hydraulic failure (e.g., catastrophic xylem embolisms) during drought may be the proximate cause of death, occurring before true C starvation occurs. Few studies have investigated specifically the mechanism(s) of tree death, and no published studies that we know of have quantified changes in NSC during mortality. EXPERIMENTAL DESIGN AND HYPOTHESES We conducted two studies that investigated whole-tree and tissue-specific C relations (photosynthetic C gain, respiration, dry-mass gain, and NSC pools) in Pinus flexilis seedlings during the initial establishment phase, which is characterized by progressive drought during summer. We measured survival, growth and biomass allocation, and C-balance physiology (photosynthetic C-gain and chlorophyll fluorescence, respiration C-use, and NSC concentrations) from germination to mortality. We hypothesized that 1) stomatal and biochemical limitations to C gain would constrain seedling survival (through inadequate seasonal C-balance), as has been shown for conifer seedlings near alpine treeline; 2) hydraulic constraints (embolisms and

  11. Effects of high-severity fire drove the population collapse of the subalpine Tasmanian endemic conifer Athrotaxis cupressoides.

    PubMed

    Holz, Andrés; Wood, Sam W; Veblen, Thomas T; Bowman, David M J S

    2015-01-01

    Athrotaxis cupressoides is a slow-growing and long-lived conifer that occurs in the subalpine temperate forests of Tasmania, a continental island to the south of Australia. In 1960-1961, human-ignited wildfires occurred during an extremely dry summer that killed many A. cupressoides stands on the high plateau in the center of Tasmania. That fire year, coupled with subsequent regeneration failure, caused a loss of ca. 10% of the geographic extent of this endemic Tasmanian forest type. To provide historical context for these large-scale fire events, we (i) collected dendroecological, floristic, and structural data, (ii) documented the postfire survival and regeneration of A. cupressoides and co-occurring understory species, and (iii) assessed postfire understory plant community composition and flammability. We found that fire frequency did not vary following the arrival of European settlers, and that A. cupressoides populations were able to persist under a regime of low-to-mid severity fires prior to the 1960 fires. Our data indicate that the 1960 fires were (i) of greater severity than previous fires, (ii) herbivory by native marsupials may limit seedling survival in both burned and unburned A. cupressoides stands, and (iii) the loss of A. cupressoides populations is largely irreversible given the relatively high fuel loads of postfire vegetation communities that are dominated by resprouting shrubs. We suggest that the feedback between regeneration failure and increased flammability will be further exacerbated by a warmer and drier climate causing A. cupressoides to contract to the most fire-proof landscape settings. PMID:25044347

  12. Water-use responses of ‘living fossil’ conifers to CO2 enrichment in a simulated Cretaceous polar environment

    PubMed Central

    Llorens, Laura; Osborne, Colin P.; Beerling, David J.

    2009-01-01

    Background and Aims During the Mesozoic, the polar regions supported coniferous forests that experienced warm climates, a CO2-rich atmosphere and extreme seasonal variations in daylight. How the interaction between the last two factors might have influenced water use of these conifers was investigated. An experimental approach was used to test the following hypotheses: (1) the expected beneficial effects of elevated [CO2] on water-use efficiency (WUE) are reduced or lost during the 24-h light of the high-latitude summer; and (2) elevated [CO2] reduces plant water use over the growing season. Methods Measurements of leaf and whole-plant gas exchange, and leaf-stable carbon isotope composition were made on one evergreen (Sequoia sempervirens) and two deciduous (Metasequoia glyptostroboides and Taxodium distichum) ‘living fossil’ coniferous species after 3 years' growth in controlled-environment simulated Cretaceous Arctic (69°N) conditions at either ambient (400 µmol mol−1) or elevated (800 µmol mol−1) [CO2]. Key Results Stimulation of whole-plant WUE (WUEP) by CO2 enrichment was maintained over the growing season for the three studied species but this pattern was not reflected in patterns of WUE inferred from leaf-scale gas exchange measurements (iWUEL) and δ13C of foliage (tWUEL). This response was driven largely by increased rates of carbon uptake, because there was no overall CO2 effect on daily whole-plant transpiration or whole-plant water loss integrated over the study period. Seasonal patterns of tWUEL differed from those measured for iWUEL. The results suggest caution against over simplistic interpretations of WUEP based on leaf isotopic composition. Conclusions The data suggest that the efficiency of whole-tree water use may be improved by CO2 enrichment in a simulated high-latitude environment, but that transpiration is relatively insensitive to atmospheric CO2 in the living fossil species investigated. PMID:19447810

  13. Different growth sensitivity to climate of the conifer Juniperus thurifera on both sides of the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    DeSoto, Lucía; Varino, Filipa; Andrade, José P.; Gouveia, Celia M.; Campelo, Filipe; Trigo, Ricardo M.; Nabais, Cristina

    2014-12-01

    Mediterranean plants cope with cold wet winters and dry hot summers, with a drought gradient from northwest to southeast. Limiting climatic conditions have become more pronounced in the last decades due to the warming trend and rainfall decrease. Juniperus thurifera L., a long-lived conifer tree endemic to the western Mediterranean region, has a disjunct distribution in Europe and Africa, making it a suitable species to study sensitivity to climate in both sides of the Mediterranean Basin. Tree-ring width chronologies were built for three J. thurifera stands at Spain (Europe) and three in Morocco (Africa) and correlated with monthly temperature and precipitation. The temporal stability of climate-growth relationships was assessed using moving correlations; the drought effect on growth was calculated using the monthly standardized precipitation-evapotranspiration index (SPEI) at different temporal scales. In the wettest stands, increasing spring temperature and summer precipitation enhanced growth, while in the driest stands, growth was enhanced by higher spring precipitation and lower summer temperature. The climate-growth correlations shifted during the twentieth century, especially since the 1970s. Particularly noticeable is the recent negative correlation with previous autumn and winter precipitation in the wettest stands of J. thurifera, probably related with an effect of cloud cover or flooding on carbon storage depletion for next year growth. The driest stands were affected by drought at long time scales, while the wettest stands respond to drought at short time scales. This reveals a different strategy to cope with drought conditions, with populations from drier sites able to cope with short periods of water deficit.

  14. Is ecological speciation a major trend in aphids? Insights from a molecular phylogeny of the conifer-feeding genus Cinara

    PubMed Central

    2013-01-01

    Introduction In the past decade ecological speciation has been recognized as having an important role in the diversification of plant-feeding insects. Aphids are host-specialised phytophagous insects that mate on their host plants and, as such, they are prone to experience reproductive isolation linked with host plant association that could ultimately lead to species formation. The generality of such a scenario remains to be tested through macroevolutionary studies. To explore the prevalence of host-driven speciation in the diversification of the aphid genus Cinara and to investigate alternative modes of speciation, we reconstructed a phylogeny of this genus based on mitochondrial, nuclear and Buchnera aphidicola DNA sequence fragments and applied a DNA-based method of species delimitation. Using a recent software (PhyloType), we explored evolutionary transitions in host-plant genera, feeding sites and geographic distributions in the diversification of Cinara and investigated how transitions in these characters have accompanied speciation events. Results The diversification of Cinara has been constrained by host fidelity to conifer genera sometimes followed by sequential colonization onto different host species and by feeding-site specialisation. Nevertheless, our analyses suggest that, at the most, only half of the speciation events were accompanied by ecological niche shifts. The contribution of geographical isolation in the speciation process is clearly apparent in the occurrence of species from two continents in the same clades in relatively terminal positions in our phylogeny. Furthermore, in agreement with predictions from scenarios in which geographic isolation accounts for speciation events, geographic overlap between species increased significantly with time elapsed since their separation. Conclusions The history of Cinara offers a different perspective on the mode of speciation of aphids than that provided by classic models such as the pea aphid. In this

  15. Effects of high-severity fire drove the population collapse of the subalpine Tasmanian endemic conifer Athrotaxis cupressoides.

    PubMed

    Holz, Andrés; Wood, Sam W; Veblen, Thomas T; Bowman, David M J S

    2015-01-01

    Athrotaxis cupressoides is a slow-growing and long-lived conifer that occurs in the subalpine temperate forests of Tasmania, a continental island to the south of Australia. In 1960-1961, human-ignited wildfires occurred during an extremely dry summer that killed many A. cupressoides stands on the high plateau in the center of Tasmania. That fire year, coupled with subsequent regeneration failure, caused a loss of ca. 10% of the geographic extent of this endemic Tasmanian forest type. To provide historical context for these large-scale fire events, we (i) collected dendroecological, floristic, and structural data, (ii) documented the postfire survival and regeneration of A. cupressoides and co-occurring understory species, and (iii) assessed postfire understory plant community composition and flammability. We found that fire frequency did not vary following the arrival of European settlers, and that A. cupressoides populations were able to persist under a regime of low-to-mid severity fires prior to the 1960 fires. Our data indicate that the 1960 fires were (i) of greater severity than previous fires, (ii) herbivory by native marsupials may limit seedling survival in both burned and unburned A. cupressoides stands, and (iii) the loss of A. cupressoides populations is largely irreversible given the relatively high fuel loads of postfire vegetation communities that are dominated by resprouting shrubs. We suggest that the feedback between regeneration failure and increased flammability will be further exacerbated by a warmer and drier climate causing A. cupressoides to contract to the most fire-proof landscape settings.

  16. Different growth sensitivity to climate of the conifer Juniperus thurifera on both sides of the Mediterranean Sea.

    PubMed

    DeSoto, Lucía; Varino, Filipa; Andrade, José P; Gouveia, Celia M; Campelo, Filipe; Trigo, Ricardo M; Nabais, Cristina

    2014-12-01

    Mediterranean plants cope with cold wet winters and dry hot summers, with a drought gradient from northwest to southeast. Limiting climatic conditions have become more pronounced in the last decades due to the warming trend and rainfall decrease. Juniperus thurifera L., a long-lived conifer tree endemic to the western Mediterranean region, has a disjunct distribution in Europe and Africa, making it a suitable species to study sensitivity to climate in both sides of the Mediterranean Basin. Tree-ring width chronologies were built for three J. thurifera stands at Spain (Europe) and three in Morocco (Africa) and correlated with monthly temperature and precipitation. The temporal stability of climate-growth relationships was assessed using moving correlations; the drought effect on growth was calculated using the monthly standardized precipitation-evapotranspiration index (SPEI) at different temporal scales. In the wettest stands, increasing spring temperature and summer precipitation enhanced growth, while in the driest stands, growth was enhanced by higher spring precipitation and lower summer temperature. The climate-growth correlations shifted during the twentieth century, especially since the 1970s. Particularly noticeable is the recent negative correlation with previous autumn and winter precipitation in the wettest stands of J. thurifera, probably related with an effect of cloud cover or flooding on carbon storage depletion for next year growth. The driest stands were affected by drought at long time scales, while the wettest stands respond to drought at short time scales. This reveals a different strategy to cope with drought conditions, with populations from drier sites able to cope with short periods of water deficit.

  17. Nocturnal transpiration causing disequilibrium between soil and stem predawn water potential in mixed conifer forests of Idaho.

    PubMed

    Kavanagh, Kathleen L; Pangle, Robert; Schotzko, Alisa D

    2007-04-01

    Soil water potential (Psi(s)) is often estimated by measuring leaf water potential before dawn (Psi(pd)), based on the assumption that the plant water status has come into equilibrium with that of the soil. However, it has been documented for a number of plant species that stomata do not close completely at night, allowing for nocturnal transpiration and thus preventing nocturnal soil-plant water potential equilibration. The potential for nighttime transpiration necessitates testing the assumption of nocturnal equilibration before accepting Psi(pd) as a valid estimate of Psi(s). We determined the magnitude of disequilibrium between Psi(pd) and Psi(s) in four temperate conifer species across three height classes through a replicated study in northern Idaho. Based on both stomatal conductance and sap flux measurements, we confirmed that the combination of open stomata and high nocturnal atmospheric vapor pressure deficit (D) resulted in nocturnal transpiration in all four species. Nocturnal stomatal conductance (g(s-noc)) averaged about 33% of mid-morning conductance values. We used species-specific estimates of g(s-noc) and leaf specific conductance to correct Psi(pd) values for nocturnal transpiration at the time the samples were collected. Compared with the unadjusted values, corrected values reflected a significantly higher Psi(pd) (when D > 0.12 kPa). These results demonstrate that comparisons of Psi(pd) among species, canopy height classes and sites, and across growing seasons can be influenced by differential amounts of nocturnal transpiration, leading to flawed results. Consequently, it is important to account for the presence of nocturnal transpiration, either through a properly parameterized model or by making Psi(pd) measurements when D is sufficiently low that it cannot drive nocturnal transpiration. Violating these conditions will likely result in underestimation of Psi(s).

  18. Tree Morphologic Plasticity Explains Deviation from Metabolic Scaling Theory in Semi-Arid Conifer Forests, Southwestern USA

    PubMed Central

    O’Connor, Christopher D.; Lynch, Ann M.

    2016-01-01

    A significant concern about Metabolic Scaling Theory (MST) in real forests relates to consistent differences between the values of power law scaling exponents of tree primary size measures used to estimate mass and those predicted by MST. Here we consider why observed scaling exponents for diameter and height relationships deviate from MST predictions across three semi-arid conifer forests in relation to: (1) tree condition and physical form, (2) the level of inter-tree competition (e.g. open vs closed stand structure), (3) increasing tree age, and (4) differences in site productivity. Scaling exponent values derived from non-linear least-squares regression for trees in excellent condition (n = 381) were above the MST prediction at the 95% confidence level, while the exponent for trees in good condition were no different than MST (n = 926). Trees that were in fair or poor condition, characterized as diseased, leaning, or sparsely crowned had exponent values below MST predictions (n = 2,058), as did recently dead standing trees (n = 375). Exponent value of the mean-tree model that disregarded tree condition (n = 3,740) was consistent with other studies that reject MST scaling. Ostensibly, as stand density and competition increase trees exhibited greater morphological plasticity whereby the majority had characteristically fair or poor growth forms. Fitting by least-squares regression biases the mean-tree model scaling exponent toward values that are below MST idealized predictions. For 368 trees from Arizona with known establishment dates, increasing age had no significant impact on expected scaling. We further suggest height to diameter ratios below MST relate to vertical truncation caused by limitation in plant water availability. Even with environmentally imposed height limitation, proportionality between height and diameter scaling exponents were consistent with the predictions of MST. PMID:27391084

  19. Tree Morphologic Plasticity Explains Deviation from Metabolic Scaling Theory in Semi-Arid Conifer Forests, Southwestern USA.

    PubMed

    Swetnam, Tyson L; O'Connor, Christopher D; Lynch, Ann M

    2016-01-01

    A significant concern about Metabolic Scaling Theory (MST) in real forests relates to consistent differences between the values of power law scaling exponents of tree primary size measures used to estimate mass and those predicted by MST. Here we consider why observed scaling exponents for diameter and height relationships deviate from MST predictions across three semi-arid conifer forests in relation to: (1) tree condition and physical form, (2) the level of inter-tree competition (e.g. open vs closed stand structure), (3) increasing tree age, and (4) differences in site productivity. Scaling exponent values derived from non-linear least-squares regression for trees in excellent condition (n = 381) were above the MST prediction at the 95% confidence level, while the exponent for trees in good condition were no different than MST (n = 926). Trees that were in fair or poor condition, characterized as diseased, leaning, or sparsely crowned had exponent values below MST predictions (n = 2,058), as did recently dead standing trees (n = 375). Exponent value of the mean-tree model that disregarded tree condition (n = 3,740) was consistent with other studies that reject MST scaling. Ostensibly, as stand density and competition increase trees exhibited greater morphological plasticity whereby the majority had characteristically fair or poor growth forms. Fitting by least-squares regression biases the mean-tree model scaling exponent toward values that are below MST idealized predictions. For 368 trees from Arizona with known establishment dates, increasing age had no significant impact on expected scaling. We further suggest height to diameter ratios below MST relate to vertical truncation caused by limitation in plant water availability. Even with environmentally imposed height limitation, proportionality between height and diameter scaling exponents were consistent with the predictions of MST.

  20. Tree Morphologic Plasticity Explains Deviation from Metabolic Scaling Theory in Semi-Arid Conifer Forests, Southwestern USA.

    PubMed

    Swetnam, Tyson L; O'Connor, Christopher D; Lynch, Ann M

    2016-01-01

    A significant concern about Metabolic Scaling Theory (MST) in real forests relates to consistent differences between the values of power law scaling exponents of tree primary size measures used to estimate mass and those predicted by MST. Here we consider why observed scaling exponents for diameter and height relationships deviate from MST predictions across three semi-arid conifer forests in relation to: (1) tree condition and physical form, (2) the level of inter-tree competition (e.g. open vs closed stand structure), (3) increasing tree age, and (4) differences in site productivity. Scaling exponent values derived from non-linear least-squares regression for trees in excellent condition (n = 381) were above the MST prediction at the 95% confidence level, while the exponent for trees in good condition were no different than MST (n = 926). Trees that were in fair or poor condition, characterized as diseased, leaning, or sparsely crowned had exponent values below MST predictions (n = 2,058), as did recently dead standing trees (n = 375). Exponent value of the mean-tree model that disregarded tree condition (n = 3,740) was consistent with other studies that reject MST scaling. Ostensibly, as stand density and competition increase trees exhibited greater morphological plasticity whereby the majority had characteristically fair or poor growth forms. Fitting by least-squares regression biases the mean-tree model scaling exponent toward values that are below MST idealized predictions. For 368 trees from Arizona with known establishment dates, increasing age had no significant impact on expected scaling. We further suggest height to diameter ratios below MST relate to vertical truncation caused by limitation in plant water availability. Even with environmentally imposed height limitation, proportionality between height and diameter scaling exponents were consistent with the predictions of MST. PMID:27391084

  1. Biogeochemical legacy of prescribed fire in a giant sequoia - Mixed conifer forest: A 16-year record of watershed balances

    USGS Publications Warehouse

    Engle, D.L.; Sickman, J.O.; Moore, C.M.; Esperanza, A.M.; Melack, J.M.; Keeley, J.E.

    2008-01-01

    The effects of prescription burning on watershed balances of major ions in mixed conifer forest were examined in a 16-year paired catchment study in Sequoia National Park, California. The objective was to determine whether fire-related changes in watershed balances persist as long as estimated low-end natural fire-return intervals (???10 years), and whether cumulative net export caused by fire could deplete nutrient stocks between successive fires. Inputs (wet + dry deposition) and outputs (stream export) of N, S, Cl-, HCO3-, Ca2+, Mg2+, Na+, K+, H+, and SiO2 were measured for 7 years preceding, and 9 years following, a prescribed burn of one of the catchments. After fire, runoff coefficients increased by 7% (in dry years) to 35% (in wet years). Inorganic N was elevated in stream water for 3 years after fire. Increased export of water, SO42-, Cl-,SiO2, and base cations continued through the end of the study. Pools and processes attributed to fire led to the cumulative loss, per hectare, of 1.2 kg N, 16 kg S, 25 kg Cl-, 130 kg Ca2+, 19 kg Mg2+, 71 kg Na+, 29 kg K+ and 192 kg Si, above that predicted by prefire regression equations relating export in the paired catchments. This additional export equaled <1% of the N, up to one-third of the Ca and Mg, and up to three-fourths of the K, contained in the forest floor prior to combustion. Changes in watershed balances indicated that low-end natural fire-return intervals may prevent complete reaccumulation of several elements between fires. Copyright 2008 by the American Geophysical Union.

  2. Drought, Frost, Rain and Sunshine. Four Years of Sap Flow Measurements for One of the World's Largest Conifers

    NASA Astrophysics Data System (ADS)

    Macinnis-Ng, C.; Taylor, D. T.; Kaplick, J.; Clearwater, M.

    2015-12-01

    Amongst the largest and longest lived conifers in the world, the endemic New Zealand kauri, Agathis australis, provides a proxy-climate record dating back 4000 y. Tree-ring widths provide a strong indicator of the occurrence of El Niño Southern Oscillation (ENSO) events. We are measuring physiological processes, including carbon uptake and loss, leaf-scale gas exchange and sap flow together with meteorological data to explore the mechanisms of the climate response of this iconic and culturally significant species. In this continuous 15 min time interval sap flow dataset spanning four years, we have captured very wet and very dry summer periods. Winter flow rates peaked lower than summer flow rates and winter flow also started later and finished earlier in the day, resulting in less water use. Larger, canopy dominant trees (DBH up to 176 cm) had large sapwood area (sapwood depth up to 18 cm) and faster flow rates and therefore dominated stand water use. During dry periods, smaller trees (DBH 20-80 cm) were more responsive to dry soils than larger trees, suggesting access to deeper soil water stores. Leaf-scale gas exchange rates were low with very low stomatal conductance values reflecting known vulnerability to xylem embolism. Night-time refilling of sapwood was particularly evident during the summer drought with evidence that refilling was incomplete as the drought progressed. Photosynthetically active radiation and vapour pressure deficit are strongly correlated with sap flow across all seasons, a promising indicator for future modelling work on this dataset. Water saving strategies and stand-scale water budgets are discussed.

  3. Avian community responses to post-fire forest structure: Implications for fire management in mixed conifer forests

    USGS Publications Warehouse

    White, Angela M.; Manley, Patricia N.; Tarbill, Gina; Richardson, T.L.; Russell, Robin E.; Safford, Hugh D.; Dobrowski, Solomon Z.

    2015-01-01

    Fire is a natural process and the dominant disturbance shaping plant and animal communities in many coniferous forests of the western US. Given that fire size and severity are predicted to increase in the future, it has become increasingly important to understand how wildlife responds to fire and post-fire management. The Angora Fire burned 1243 hectares of mixed conifer forest in South Lake Tahoe, California. We conducted avian point counts for the first 3 years following the fire in burned and unburned areas to investigate which habitat characteristics are most important for re-establishing or maintaining the native avian community in post-fire landscapes. We used a multi-species occurrence model to estimate how avian species are influenced by the density of live and dead trees and shrub cover. While accounting for variations in the detectability of species, our approach estimated the occurrence probabilities of all species detected including those that were rare or observed infrequently. Although all species encountered in this study were detected in burned areas, species-specific modeling results predicted that some species were strongly associated with specific post-fire conditions, such as a high density of dead trees, open-canopy conditions or high levels of shrub cover that occur at particular burn severities or at a particular time following fire. These results indicate that prescribed fire or managed wildfire which burns at low to moderate severity without at least some high-severity effects is both unlikely to result in the species assemblages that are unique to post-fire areas or to provide habitat for burn specialists. Additionally, the probability of occurrence for many species was associated with high levels of standing dead trees indicating that intensive post-fire harvest of these structures could negatively impact habitat of a considerable proportion of the avian community.

  4. Carbon fluxes acclimate more strongly to elevated growth temperatures than to elevated CO2 concentrations in a northern conifer.

    PubMed

    Kroner, Yulia; Way, Danielle A

    2016-08-01

    Increasing temperatures and atmospheric CO2 concentrations will affect tree carbon fluxes, generating potential feedbacks between forests and the global climate system. We studied how elevated temperatures and CO2 impacted leaf carbon dynamics in Norway spruce (Picea abies), a dominant northern forest species, to improve predictions of future photosynthetic and respiratory fluxes from high-latitude conifers. Seedlings were grown under ambient (AC, c. 435 μmol mol(-1) ) or elevated (EC, 750 μmol mol(-1) ) CO2 concentrations at ambient, +4 °C, or +8 °C growing temperatures. Photosynthetic rates (Asat ) were high in +4 °C/EC seedlings and lowest in +8 °C spruce, implying that moderate, but not extreme, climate change may stimulate carbon uptake. Asat , dark respiration (Rdark ), and light respiration (Rlight ) rates acclimated to temperature, but not CO2 : the thermal optimum of Asat increased, and Rdark and Rlight were suppressed under warming. In all treatments, the Q10 of Rlight (the relative increase in respiration for a 10 °C increase in leaf temperature) was 35% higher than the Q10 of Rdark , so the ratio of Rlight to Rdark increased with rising leaf temperature. However, across all treatments and a range of 10-40 °C leaf temperatures, a consistent relationship between Rlight and Rdark was found, which could be used to model Rlight in future climates. Acclimation reduced daily modeled respiratory losses from warm-grown seedlings by 22-56%. When Rlight was modeled as a constant fraction of Rdark , modeled daily respiratory losses were 11-65% greater than when using measured values of Rlight . Our findings highlight the impact of acclimation to future climates on predictions of carbon uptake and losses in northern trees, in particular the need to model daytime respiratory losses from direct measurements of Rlight or appropriate relationships with Rdark .

  5. Conifer seedling recruitment across a gradient from forest to alpine tundra: effects of species, provenance, and site

    USGS Publications Warehouse

    Castanha, C.; Torn, M.S.; Germino, M.J.; Weibel, B.; Kueppers, L.M.

    2013-01-01

    Background: Seedling germination and survival is a critical control on forest ecosystem boundaries, such as at the alpine–treeline ecotone. In addition, while it is known that species respond individualistically to the same suite of environmental drivers, the potential additional effect of local adaptation on seedling success has not been evaluated. Aims: To determine whether local adaptation may influence the position and movement of forest ecosystem boundaries, we quantified conifer seedling recruitment in common gardens across a subalpine forest to alpine tundra gradient at Niwot Ridge, Colorado, USA. Methods: We studied Pinus flexilis and Picea engelmannii grown from seed collected locally at High (3400 m a.s.l.) and Low (3060 m a.s.l.) elevations. We monitored emergence and survival of seeds sown directly into plots and survival of seedlings germinated indoors and transplanted after snowmelt. Results: Emergence and survival through the first growing season was greater for P. flexilis than P. engelmannii and for Low compared with High provenances. Yet survival through the second growing season was similar for both species and provenances. Seedling emergence and survival tended to be greatest in the subalpine forest and lowest in the alpine tundra. Survival was greater for transplants than for field-germinated seedlings. Conclusions: These results suggest that survival through the first few weeks is critical to the establishment of natural germinants. In addition, even small distances between seed sources can have a significant effect on early demographic performance – a factor that has rarely been considered in previous studies of tree recruitment and species range shifts.

  6. Evolution of conifer diterpene synthases: diterpene resin acid biosynthesis in lodgepole pine and jack pine involves monofunctional and bifunctional diterpene synthases.

    PubMed

    Hall, Dawn E; Zerbe, Philipp; Jancsik, Sharon; Quesada, Alfonso Lara; Dullat, Harpreet; Madilao, Lina L; Yuen, Macaire; Bohlmann, Jörg

    2013-02-01

    Diterpene resin acids (DRAs) are major components of pine (Pinus spp.) oleoresin. They play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. The core structures of DRAs are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (GGPP) by diterpene synthases (diTPSs). Previously described gymnosperm diTPSs of DRA biosynthesis are bifunctional enzymes that catalyze the initial bicyclization of GGPP followed by rearrangement of a (+)-copalyl diphosphate intermediate at two discrete class II and class I active sites. In contrast, similar diterpenes of gibberellin primary (i.e. general) metabolism are produced by the consecutive activity of two monofunctional class II and class I diTPSs. Using high-throughput transcriptome sequencing, we discovered 11 diTPS from jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta). Three of these were orthologous to known conifer bifunctional levopimaradiene/abietadiene synthases. Surprisingly, two sets of orthologous PbdiTPSs and PcdiTPSs were monofunctional class I enzymes that lacked functional class II active sites and converted (+)-copalyl diphosphate, but not GGPP, into isopimaradiene and pimaradiene as major products. Diterpene profiles and transcriptome sequences of lodgepole pine and jack pine are consistent with roles for these diTPSs in DRA biosynthesis. The monofunctional class I diTPSs of DRA biosynthesis form a new clade within the gymnosperm-specific TPS-d3 subfamily that evolved from bifunctional diTPS rather than monofunctional enzymes (TPS-c and TPS-e) of gibberellin metabolism. Homology modeling suggested alterations in the class I active site that may have contributed to their functional specialization relative to other conifer diTPSs. PMID:23370714

  7. Xylem Embolism in Response to Freeze-Thaw Cycles and Water Stress in Ring-Porous, Diffuse-Porous, and Conifer Species 1

    PubMed Central

    Sperry, John S.; Sullivan, June E. M.

    1992-01-01

    Vulnerability to xylem embolism by freeze-thaw cycles and water stress was quantified in ring-porous (Quercus gambelii Nutt.), diffuse-porous (Populus tremuloides Michx., Betula occidentalis Hook.), and conifer species (Abies lasiocarpa Nutt., Juniperus scopulorum Sarg.). Embolism was measured by its reduction of xylem hydraulic conductivity; it was induced by xylem tension (water-stress response) and by a tension plus a freeze-thaw cycle (freeze response). Conifers showed little (Juniperus) or no (Abies) freeze response even to repeated cycles. In contrast, Quercus embolized more than 90% by freezing at tensions below 0.2 MPa, whereas similar embolism without freezing required tensions above 4.5 MPa. Diffuse-porous trees (Betula, Populus) showed an intermediate freeze response. The magnitude of the freeze response was correlated with conduit volume but occurred at higher tensions than predicted from theory. Large early-wood vessels (2.8 × 10−9 m3) in oak were most vulnerable to embolism by freezing, small vessels in Populus and Betula were intermediate (approximately 7 × 10−11 m3), and tracheids in conifers (about 3 × 10−13 m3) were most resistant. The same trend was found within a stem: embolism by freeze-thawing occurred preferentially in wider conduits. The water-stress response was not correlated with conduit volume; previous work indicates it is a function of interconduit pit membrane structure. Native embolism levels during winter corroborated laboratory results on freezing: Quercus embolized 95% with the first fall freeze, Populus and Betula showed gradual increases to more than 90% embolism by winter's end, and Abies remained below 30%. PMID:16653035

  8. Evolution of Conifer Diterpene Synthases: Diterpene Resin Acid Biosynthesis in Lodgepole Pine and Jack Pine Involves Monofunctional and Bifunctional Diterpene Synthases1[W][OA

    PubMed Central

    Hall, Dawn E.; Zerbe, Philipp; Jancsik, Sharon; Quesada, Alfonso Lara; Dullat, Harpreet; Madilao, Lina L.; Yuen, Macaire; Bohlmann, Jörg

    2013-01-01

    Diterpene resin acids (DRAs) are major components of pine (Pinus spp.) oleoresin. They play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. The core structures of DRAs are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (GGPP) by diterpene synthases (diTPSs). Previously described gymnosperm diTPSs of DRA biosynthesis are bifunctional enzymes that catalyze the initial bicyclization of GGPP followed by rearrangement of a (+)-copalyl diphosphate intermediate at two discrete class II and class I active sites. In contrast, similar diterpenes of gibberellin primary (i.e. general) metabolism are produced by the consecutive activity of two monofunctional class II and class I diTPSs. Using high-throughput transcriptome sequencing, we discovered 11 diTPS from jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta). Three of these were orthologous to known conifer bifunctional levopimaradiene/abietadiene synthases. Surprisingly, two sets of orthologous PbdiTPSs and PcdiTPSs were monofunctional class I enzymes that lacked functional class II active sites and converted (+)-copalyl diphosphate, but not GGPP, into isopimaradiene and pimaradiene as major products. Diterpene profiles and transcriptome sequences of lodgepole pine and jack pine are consistent with roles for these diTPSs in DRA biosynthesis. The monofunctional class I diTPSs of DRA biosynthesis form a new clade within the gymnosperm-specific TPS-d3 subfamily that evolved from bifunctional diTPS rather than monofunctional enzymes (TPS-c and TPS-e) of gibberellin metabolism. Homology modeling suggested alterations in the class I active site that may have contributed to their functional specialization relative to other conifer diTPSs. PMID:23370714

  9. Macro-particle charcoal C content following prescribed burning in a mixed-conifer forest, Sierra Nevada, California.

    PubMed

    Wiechmann, Morgan L; Hurteau, Matthew D; Kaye, Jason P; Miesel, Jessica R

    2015-01-01

    Fire suppression and changing climate have resulted in increased large wildfire frequency and severity in the western United States, causing carbon cycle impacts. Forest thinning and prescribed burning reduce high-severity fire risk, but require removal of biomass and emissions of carbon from burning. During each fire a fraction of the burning vegetation and soil organic matter is converted into charcoal, a relatively stable carbon form. We sought to quantify the effects of pre-fire fuel load and type on charcoal carbon produced by biomass combusted in a prescribed burn under different thinning treatments and to identify more easily measured predictors of charcoal carbon mass in a historically frequent-fire mixed-conifer forest. We hypothesized that charcoal carbon produced from coarse woody debris (CWD) during prescribed burning would be greater than that produced from fine woody debris (FWD). We visually quantified post-treatment charcoal carbon content in the O-horizon and the A-horizon beneath CWD (> 30 cm diameter) and up to 60 cm from CWD that was present prior to treatment. We found no difference in the size of charcoal carbon pools from CWD (treatment means ranged from 0.3-2.0 g m-2 of A-horizon and 0.0-1.7 g m-2 of O-horizon charcoal) and FWD (treatment means ranged from 0.2-1.7 g m-2 of A-horizon and 0.0-1.5 g m-2 of O-horizon charcoal). We also compared treatments and found that the burn-only, understory-thin and burn, and overstory-thin and burn treatments had significantly more charcoal carbon than the control. Charcoal carbon represented 0.29% of total ecosystem carbon. We found that char mass on CWD was an important predictor of charcoal carbon mass, but only explained 18-35% of the variation. Our results help improve our understanding of the effects forest restoration treatments have on ecosystem carbon by providing additional information about charcoal carbon content.

  10. The diagenetic behavior of cutin acids in buried conifer needles and sediments from a coastal marine environment

    NASA Astrophysics Data System (ADS)

    Goñi, Miguel A.; Hedges, John I.

    1990-11-01

    Whole green, litter, and sedimentary fir, hemlock, and cedar needles and bulk sediments collected from the Dabob Bay region in Washington state were analyzed for their cutin-derived CuO reaction products. All samples yielded dihydroxyhexadecanoic acid isomers (x,ω-C 16), 16-hydroxyhexa-decanoic acid (ω-C 16), 14-hydroxytetradecanoic acid (ω-C 14), and 18-hydroxyoctadec-9-enoic acid (ω-C 18: 1) as the major cutin acids. Fir/hemlock needle mixtures were characterized by a high abundance of the 9,16-dihydroxyhexadecanoic acid positional isomer, while cedar needles produced primarily the 10,16-dihydroxy counterpart. Cutin acids accounted for ~3% of tissue C in green needles, ~4% in needle litter, 0.5-1.5% in sedimentary needles, and about 0.1% of the organic carbon (OC) in bulk sediments. Approximately 80% of the original cutin acids in fresh green needles were lost from the deepest (~100 years old) sedimentary tissues. Cutin was more reactive than lignin and polysaccharides, but more stable than the cyclitol components of the same needles. Comparative diagenetic losses of the individual cutin acids were not uniform and suggest that additional hydroxy groups and the presence of C double bonds both increase overall reactivity. The relative stability series derived for all the molecular constituents measured is: total vanillyl phenols > total P- hydroxy phenols, ferulic acid, most aldoses, bulk organic matter > mannose, ω-C 14, ω-C 16 ⩾ ω-C 18:1 > glucose, p- coumaric acid, x, ω-C 16 > all cyclitols. Diagenetically induced changes in the various cutin parameters used to characterize nonwoody vascular plant tissues were not large enough to confuse degraded conifer tissues with other cutin sources. Based on these trends, the finely disseminated cutin-bearing tissues in Dabob Bay sediments appear to be comprised approximately of equal amounts of highly degraded fir/hemlock and cedar needle fragments. According to this estimate, nonwoody vascular plant debris

  11. Macro-particle charcoal C content following prescribed burning in a mixed-conifer forest, Sierra Nevada, California.

    PubMed

    Wiechmann, Morgan L; Hurteau, Matthew D; Kaye, Jason P; Miesel, Jessica R

    2015-01-01

    Fire suppression and changing climate have resulted in increased large wildfire frequency and severity in the western United States, causing carbon cycle impacts. Forest thinning and prescribed burning reduce high-severity fire risk, but require removal of biomass and emissions of carbon from burning. During each fire a fraction of the burning vegetation and soil organic matter is converted into charcoal, a relatively stable carbon form. We sought to quantify the effects of pre-fire fuel load and type on charcoal carbon produced by biomass combusted in a prescribed burn under different thinning treatments and to identify more easily measured predictors of charcoal carbon mass in a historically frequent-fire mixed-conifer forest. We hypothesized that charcoal carbon produced from coarse woody debris (CWD) during prescribed burning would be greater than that produced from fine woody debris (FWD). We visually quantified post-treatment charcoal carbon content in the O-horizon and the A-horizon beneath CWD (> 30 cm diameter) and up to 60 cm from CWD that was present prior to treatment. We found no difference in the size of charcoal carbon pools from CWD (treatment means ranged from 0.3-2.0 g m-2 of A-horizon and 0.0-1.7 g m-2 of O-horizon charcoal) and FWD (treatment means ranged from 0.2-1.7 g m-2 of A-horizon and 0.0-1.5 g m-2 of O-horizon charcoal). We also compared treatments and found that the burn-only, understory-thin and burn, and overstory-thin and burn treatments had significantly more charcoal carbon than the control. Charcoal carbon represented 0.29% of total ecosystem carbon. We found that char mass on CWD was an important predictor of charcoal carbon mass, but only explained 18-35% of the variation. Our results help improve our understanding of the effects forest restoration treatments have on ecosystem carbon by providing additional information about charcoal carbon content. PMID:26258533

  12. Forest Fuel Reduction and Wildfire Effects on Runoff and Evapotranspiration in Sierra Nevada Mixed-Conifer Forest

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Bales, R. C.; Conklin, M. H.

    2015-12-01

    Large, high-intensity wildfire risk in the western United States is growing, fueled by increasing vegetation density from a century of fire suppression and climatic shifts resulting in extended dry seasons. Strategically Placed Landscape Treatments (SPLATs) are a fuel reduction method designed to reduce fire risk on the entire landscape by treating only a fraction of the area. During 2011 and 2012, SPLATs were implemented in the mixed-conifer zone of the Tahoe (Last Chance study area, American River Basin) and Sierra (Sugar Pine study area, Merced River Basin) National Forests. Wildfire events were then simulated for both treated and untreated conditions. We integrated the vegetation changes with the Regional Hydro-Ecological Simulation System (RHESSys) to project impacts of fuel treatments and wildfire on runoff and evapotranspiration for the period of observed data, water years 2010-2013. Results from the model simulations show that vegetation treatments in the Last Chance study area, which removed 8.0% of the total biomass by treating 25% of the area, increased mean annual runoff by 12.0% and decreased mean annual evapotranspiration by 4.1%. Vegetation treatments in the Sugar Pine study area, which removed 7.5% of the total biomass by treating 33% of the area, increased runoff by 2.7% and decreased ET by 0.5%. Compared to pre-treatment conditions, wildfire simulations in Last Chance reduced total biomass by 38-50% when fuel treatments were not applied, resulting in a 55-67% runoff increase and a 19-23% evapotranspiration decrease. In Sugar Pine, fire simulation reduced biomass 39-43%, increasing runoff and decreasing ET by 13-15% and 1.8-2.7% respectively. Applying the same magnitude of biomass reductions equally over the entire watershed, in contrast to the localized areas of vegetation reductions due to treatment or fire, resulted in smaller impacts on runoff and evapotranspiration rates. Vegetation effects on hydrologic fluxes are greater in Last Chance than

  13. A mitochondrial DNA minisatellite reveals the postglacial history of jack pine (Pinus banksiana), a broad-range North American conifer.

    PubMed

    Godbout, Julie; Jaramillo-Correa, Juan P; Beaulieu, Jean; Bousquet, Jean

    2005-10-01

    Jack pine (Pinus banksiana Lamb.) is a broadly distributed North American conifer and its current range was covered by the Laurentian ice sheet during the last glacial maximum. To infer about the history and postglacial colonization of this boreal species, range-wide genetic variation was assessed using a new and highly variable minisatellite-like marker of the mitochondrial genome. Among the 543 trees analysed, 14 distinct haplotypes were detected, which corresponded to different repeat numbers of the 32-nucleotide minisatellite-like motif. Several haplotypes were rare with limited distribution, suggesting recent mutation events during the Holocene. At the population level, an average of 2.6 haplotypes and a mean haplotype diversity (H) of 0.328 were estimated. Population subdivision of genetic diversity was quite high with G(ST) and R(ST) values of 0.569 and 0.472, respectively. Spatial analyses identified three relatively homogeneous groups of populations presumably representative of genetically distinct glacial populations, one west and one east of the Appalachian Mountains in the United States and a third one presumably on the unglaciated northeastern coastal area in Canada. These results indicate the significant role of the northern part of the US Appalachian Mountains as a factor of vicariance during the ice age. A fourth distinct group of populations was observed in central Québec where the continental glacier retreated last. It included populations harbouring haplotypes present into the three previous groups, and it had higher level of haplotype diversity per population (H = 0.548) and lower population differentiation (G(ST) = 0.265), which indicates a zone of suture or secondary contact between the migration fronts of the three glacial populations. Introgression from Pinus contorta Dougl. var. latifolia Engelm. was apparent in one western population from Alberta. Altogether, these results indicate that the mitochondrial DNA variation of jack pine is

  14. Macro-Particle Charcoal C Content following Prescribed Burning in a Mixed-Conifer Forest, Sierra Nevada, California

    PubMed Central

    Wiechmann, Morgan L.; Hurteau, Matthew D.; Kaye, Jason P.; Miesel, Jessica R.

    2015-01-01

    Fire suppression and changing climate have resulted in increased large wildfire frequency and severity in the western United States, causing carbon cycle impacts. Forest thinning and prescribed burning reduce high-severity fire risk, but require removal of biomass and emissions of carbon from burning. During each fire a fraction of the burning vegetation and soil organic matter is converted into charcoal, a relatively stable carbon form. We sought to quantify the effects of pre-fire fuel load and type on charcoal carbon produced by biomass combusted in a prescribed burn under different thinning treatments and to identify more easily measured predictors of charcoal carbon mass in a historically frequent-fire mixed-conifer forest. We hypothesized that charcoal carbon produced from coarse woody debris (CWD) during prescribed burning would be greater than that produced from fine woody debris (FWD). We visually quantified post-treatment charcoal carbon content in the O-horizon and the A-horizon beneath CWD (> 30 cm diameter) and up to 60 cm from CWD that was present prior to treatment. We found no difference in the size of charcoal carbon pools from CWD (treatment means ranged from 0.3–2.0 g m-2 of A-horizon and 0.0–1.7 g m-2 of O-horizon charcoal) and FWD (treatment means ranged from 0.2–1.7 g m-2 of A-horizon and 0.0–1.5 g m-2 of O-horizon charcoal). We also compared treatments and found that the burn-only, understory-thin and burn, and overstory-thin and burn treatments had significantly more charcoal carbon than the control. Charcoal carbon represented 0.29% of total ecosystem carbon. We found that char mass on CWD was an important predictor of charcoal carbon mass, but only explained 18–35% of the variation. Our results help improve our understanding of the effects forest restoration treatments have on ecosystem carbon by providing additional information about charcoal carbon content. PMID:26258533

  15. Terpenes tell different tales at different scales: glimpses into the Chemical Ecology of conifer - bark beetle - microbial interactions.

    PubMed

    Raffa, Kenneth F

    2014-01-01

    Chemical signaling mediates nearly all aspects of species interactions. Our knowledge of these signals has progressed dramatically, and now includes good characterizations of the bioactivities, modes of action, biosynthesis, and genetic programming of numerous compounds affecting a wide range of species. A major challenge now is to integrate this information so as to better understand actual selective pressures under natural conditions, make meaningful predictions about how organisms and ecosystems will respond to a changing environment, and provide useful guidance to managers who must contend with difficult trade-offs among competing socioeconomic values. One approach is to place stronger emphasis on cross-scale interactions, an understanding of which can help us better connect pattern with process, and improve our ability to make mechanistically grounded predictions over large areas and time frames. The opportunity to achieve such progress has been heightened by the rapid development of new scientific and technological tools. There are significant difficulties, however: Attempts to extend arrays of lower-scale processes into higher scale functioning can generate overly diffuse patterns. Conversely, attempts to infer process from pattern can miss critically important lower-scale drivers in systems where their biological and statistical significance is negated after critical thresholds are breached. Chemical signaling in bark beetle - conifer interactions has been explored for several decades, including by the two pioneers after whom this award is named. The strong knowledge base developed by many researchers, the importance of bark beetles in ecosystem functioning, and the socioeconomic challenges they pose, establish these insects as an ideal model for studying chemical signaling within a cross-scale context. This report describes our recent work at three levels of scale: interactions of bacteria with host plant compounds and symbiotic fungi (tree level

  16. Revision of the Cretaceous fossil plant-assemblage from Gardeshwar (Gujarat, India): A conifer dominated floral association from an Upper Gondwana sequence on the West Coast of India

    NASA Astrophysics Data System (ADS)

    Jana, Brajendra Nath; King, Sarah C.; Hilton, Jason

    2013-09-01

    A small but diverse fossil plant assemblage from Gardeshwar in Gujarat Province of western India is reinvestigated, based on analysis of recently collected specimens that represent previously unrecognised taxa in combination with a critical review of previously reported taxa from the site. The assemblage is dominated by conifers including Brachyphyllum Brongniart, Elatocladus Halle, Pagiophyllum Heer, the cone Conites Sternberg, and ovulate scales of an araucarian conifer. Other plant groups are rare but include notable occurrences of the pteridophytes Lycopodites Lindley and Hutton and Gleichenia Smith, and the seed fern Sphenopteris (Brongniart) Sternberg. This assemblage is important as it represents the only datable fossils available from the Gardeshwar Formation and from the information presented we conclude it belongs to the Lower Cretaceous Allocladus-Brachyphyllum-Pagiophyllum floral biozone. The Gardeshwar assemblage association is unusual as it lacks the distinctive genus Allocladus but includes other taxa more typical of the Lower Cretaceous fern-dominated Weichselia-Onychiopsis-Gleichenia floral biozone, and may represent a transitional assemblage with characters of both biozones. However, this investigation highlights the lack of detailed stratigraphic analyses on the Lower Cretaceous sedimentary sequences of the west coast of India from which it remains uncertain if these two ‘biozones' are of different ages or whether they represent stratigraphically contemporaneous but ecologically distinct environments.

  17. Molecular control of normal and acrocona mutant seed cone development in Norway spruce (Picea abies) and the evolution of conifer ovule-bearing organs.

    PubMed

    Carlsbecker, Annelie; Sundström, Jens F; Englund, Marie; Uddenberg, Daniel; Izquierdo, Liz; Kvarnheden, Anders; Vergara-Silva, Francisco; Engström, Peter

    2013-10-01

    Reproductive organs in seed plants are morphologically divergent and their evolutionary history is often unclear. The mechanisms controlling their development have been extensively studied in angiosperms but are poorly understood in conifers and other gymnosperms. Here, we address the molecular control of seed cone development in Norway spruce, Picea abies. We present expression analyses of five novel MADS-box genes in comparison with previously identified MADS and LEAFY genes at distinct developmental stages. In addition, we have characterized the homeotic transformation from vegetative shoot to female cone and associated changes in regulatory gene expression patterns occurring in the acrocona mutant. The analyses identified genes active at the onset of ovuliferous and ovule development and identified expression patterns marking distinct domains of the ovuliferous scale. The reproductive transformation in acrocona involves the activation of all tested genes normally active in early cone development, except for an AGAMOUS-LIKE6/SEPALLATA (AGL6/SEP) homologue. This absence may be functionally associated with the nondeterminate development of the acrocona ovule-bearing scales. Our morphological and gene expression analyses give support to the hypothesis that the modern cone is a complex structure, and the ovuliferous scale the result of reductions and compactions of an ovule-bearing axillary short shoot in cones of Paleozoic conifers.

  18. Stomatal dynamics are limited by leaf hydraulics in ferns and conifers: results from simultaneous measurements of liquid and vapour fluxes in leaves.

    PubMed

    Martins, Samuel C V; McAdam, Scott A M; Deans, Ross M; DaMatta, Fábio M; Brodribb, Tim J

    2016-03-01

    Stomatal responsiveness to vapour pressure deficit (VPD) results in continuous regulation of daytime gas-exchange directly influencing leaf water status and carbon gain. Current models can reasonably predict steady-state stomatal conductance (gs ) to changes in VPD but the gs dynamics between steady-states are poorly known. Here, we used a diverse sample of conifers and ferns to show that leaf hydraulic architecture, in particular leaf capacitance, has a major role in determining the gs response time to perturbations in VPD. By using simultaneous measurements of liquid and vapour fluxes into and out of leaves, the in situ fluctuations in leaf water balance were calculated and appeared to be closely tracked by changes in gs thus supporting a passive model of stomatal control. Indeed, good agreement was found between observed and predicted gs when using a hydropassive model based on hydraulic traits. We contend that a simple passive hydraulic control of stomata in response to changes in leaf water status provides for efficient stomatal responses to VPD in ferns and conifers, leading to closure rates as fast or faster than those seen in most angiosperms.

  19. Quantitative iTRAQ proteome and comparative transcriptome analysis of elicitor-induced Norway spruce (Picea abies) cells reveals elements of calcium signaling in the early conifer defense response.

    PubMed

    Lippert, Dustin N; Ralph, Steven G; Phillips, Michael; White, Rick; Smith, Derek; Hardie, Darryl; Gershenzon, Jonathan; Ritland, Kermit; Borchers, Christoph H; Bohlmann, Jörg

    2009-01-01

    Long-lived conifer trees depend on both constitutive and induced defenses for resistance against a myriad of potential pathogens and herbivores. In species of spruce (Picea spp.), several of the late events of pathogen-, insect-, or elicitor-induced defense responses have previously been characterized at the anatomical, biochemical, transcriptome, and proteome levels in stems and needles. However, accurately measuring the early events of induced cellular responses in a conifer is technically challenging due to limitations in the precise timing of induction and tissue sampling from intact trees following insect or fungal treatment. In the present study, we used the advantages of Norway spruce (Picea abies) cell suspensions combined with chitosan elicitation to investigate the early proteome response in a conifer. A combination of iTRAQ labeling and a new design of iterative sample analysis employing data-dependent exclusion lists were used for proteome analysis. This approach improved the coverage of the spruce proteome beyond that achieved in any prior study in a conifer system. Comparison of elicitor-induced proteome and transcriptome responses in Norway spruce cells consistently identified features associated with calcium-mediated signaling and response to oxidative stress that have not previously been observed in the response of intact trees to fungal attack.

  20. Direct in situ measurement of Carbon Allocation to Mycorrhizal Fungi in a California Mixed-Conifer Forest

    NASA Astrophysics Data System (ADS)

    Allen, M. F.

    2011-12-01

    Mycorrhizal fungi represent a large allocation of C to ecosystems, based on indirect measurements (tree girdling) and glasshouse extrapolations. However, we have no direct measures carbon (C) sink, in part because technologies for studying belowground dynamics on time scales at which roots and microbes grow and die have not existed. We initiated new sensor and observation platforms belowground to characterize and quantify belowground dynamics in a California mixed-conifer ecosystem. For the first time, we directly observed growth and mortality of mycorrhizal fungi in situ. We measured soil CO2, T and θ at 5-min intervals into the soil profile. Using our automated minirhizotron (AMR) for hyphal dynamics and the Bartz minirhizotron for longer-term and spatial variation in roots and rhizomorphs, we measured root, rhizomorph, hyphal growth, and belowground phenology up to 4x daily. These data are coupled with sensors measuring eddy flux of water and CO2, sapflow for water fluxes and C fixation activity, and photographs for leaf phenology. Because our data were collected at short intervals, we can describe integrative C exchange using the DayCent model for NPP and measured NPP of rhizomorphs, and fungal hyphae. Here, we focused on an arbuscular mycorrhiza dominated meadow and an ectomycorrhizal pine/oak forest at the James Reserve, in southern California. By daily measuring hyphal growth and mortality, we constructed life-span estimates of mycorrhizal hyphae, and from these, C allocation estimates. In the meadow, the NPP was 141g/m2/y, with a productivity of fine root+internal AM fungi of 76.5g C/m2/y, and an estimated 10% of which is AM fungal C allocation (7.7 g/m2/y). Extramatrical AM hyphal peak standing crop was 10g/m2, with a lifespan of 46 days (with active hyphae persisting for ~240 days per year days). Thus, the annual AM fungal allocation was 7.7g C/m2/y internal and 52g/m2/y external, for a net allocation of 84g C/m2/y, or 60% of the estimated NPP. In the

  1. Combustion efficiency and emission factors for wildfire-season fires in mixed conifer forests of the northern Rocky Mountains, US

    NASA Astrophysics Data System (ADS)

    Urbanski, S. P.

    2013-07-01

    In the US, wildfires and prescribed burning present significant challenges to air regulatory agencies attempting to achieve and maintain compliance with air quality regulations. Fire emission factors (EF) are essential input for the emission models used to develop wildland fire emission inventories. Most previous studies quantifying wildland fire EF of temperate ecosystems have focused on emissions from prescribed burning conducted outside of the wildfire season. Little information is available on EF for wildfires in temperate forests of the conterminous US. The goal of this work is to provide information on emissions from wildfire-season forest fires in the northern Rocky Mountains, US. In August 2011, we deployed airborne chemistry instruments and sampled emissions over eight days from three wildfires and a prescribed fire that occurred in mixed conifer forests of the northern Rocky Mountains. We measured the combustion efficiency, quantified as the modified combustion efficiency (MCE), and EF for CO2, CO, and CH4. Our study average values for MCE, EFCO2, EFCO, and EFCH4 were 0.883, 1596 g kg-1, 135 g kg-1, 7.30 g kg-1, respectively. Compared with previous field studies of prescribed fires in temperate forests, the fires sampled in our study had significantly lower MCE and EFCO2 and significantly higher EFCO and EFCH4. The fires sampled in this study burned in areas reported to have moderate to heavy components of standing dead trees and down dead wood due to insect activity and previous fire, but fuel consumption data was not available. However, an analysis of MCE and fuel consumption data from 18 prescribed fires reported in the literature indicates that the availability of coarse fuels and conditions favorable for the combustion of these fuels favors low MCE fires. This analysis suggests that fuel composition was an important factor contributing to the low MCE of the fires measured in this study. This study only measured EF for CO2, CO, and CH4; however, we

  2. Lipid-content-normalized polycyclic aromatic hydrocarbons (PAHs) in the xylem of conifers can indicate historical changes in regional airborne PAHs.

    PubMed

    Kuang, Yuan-wen; Li, Jiong; Hou, En-qing

    2015-01-01

    The temporal variation of polycyclic aromatic hydrocarbons (PAHs) concentrations as well as the lipid content in the xylem of Masson pine trees sampled from the same site were determined and compared with the days of haze occurrence and with the historical PAHs reported in sedimentary cores. The patterns of the lipid content as well as the PAH concentrations based on the xylem dry weight (PAHs-DW) decreased from the heartwood to the sapwood. The trajectories of PAHs normalized by xylem lipid content (PAHs-LC) coincided well with the number of haze-occurred days and were partly similar with the historical changes in airborne PAHs recorded in the sedimentary cores. The results indicated that PAHs-LC in the xylem of conifers might reliably reflect the historical changes in airborne PAHs at a regional scale. The species-specificity should be addressed in the utility and application of dendrochemical monitoring on historical and comparative studies of airborne PAHs.

  3. Relationships of inside and outside bark diameters for young-growth mixed-conifer species in the Sierra Nevada. Forest Service research note (final). [Firs, cedars, pines

    SciTech Connect

    Dolph, K.L.

    1984-09-01

    The linear relationship of inside to outside bark diameter at breast height provides a basis for estimating diameter inside bark from diameter outside bark. Estimates of diameter inside bark and past diameter outside bark are useful in predicting growth and yield. During field seasons 1979-1982, data were obtained from stem analysis of 931 trees in young-growth stands of the mixed-conifer type on the westside Sierra Nevada of California. Species included were coast Douglas-fir, California white fir, incense-cedar, sugar pine, ponderosa pine, and Jeffrey pine. This note provides equations for estimating inside bark diameters, double bark thickness, and past outside bark diameters for each of the species studied.

  4. Effects of high atmospheric CO2 concentration on root hydraulic conductivity of conifers depend on species identity and inorganic nitrogen source.

    PubMed

    Gebauer, Tobias; Bassirirad, Hormoz

    2011-12-01

    We examined root hydraulic conductivity (L(p)) responses of one-year-old seedlings of four conifers to the combined effects of elevated CO2 and inorganic nitrogen (N) sources. We found marked interspecific differences in L(p) responses to high CO2 ranging from a 37% increase in P. abies to a 27% decrease in P. menziesii, but these effects depended on N source. The results indicate that CO2 effects on root water transport may be coupled to leaf area responses under nitrate (NO(3)(-)), but not ammonium (NH(4)(+)) dominated soils. To our knowledge, this is the first study that highlights the role of inorganic N source and species identity as critical factors that determine plant hydraulic responses to rising atmospheric CO2 levels. The results have important implications for understanding root biology in a changing climate and for models designed to predict feedbacks between rising atmospheric CO2, N deposition, and ecohydrology.

  5. Ectomycorrhizal Community Structure and Soil Characteristics of Mature Lodgepole Pine (Pinus Contorta) and Adjacent Stands of Old Growth Mixed Conifer in Yellowstone National Park, Wyoming USA

    NASA Technical Reports Server (NTRS)

    Douglas, Robert B.; Parker, V. Thomas; Cullings, Kenneth W.; Sun, Sidney (Technical Monitor)

    2003-01-01

    Forest development patterns following disturbance are known to influence the physical and chemical attributes of soils at different points in time. Changes in soil resources are thought to have a corresponding effect on ectomycorrhizal (ECM) community structure. We used molecular methods to compare below-ground ECM species richness, composition, and abundance between adjacent stands of homogenous lodgepole pine and old growth mixed conifer in Yellowstone National Park (YNP). In each stand-type we collected soil cores to both identify mycorrhizae and assess soil chemistry. Although no statistical difference was observed in the mean number of ECM root tips per core between stand types, the total number of species identified (85 versus 35) and the mean number of species per core (8.8 +/- 0.6 versus 2.5 +/- 0.3) were significantly higher in lodgepole pine. Differences between the actual and estimated species richness levels indicated that these forest types support a high number of ECM species and that undersampling was severe. Species compositions were widely disparate between stands where only four species were shared out of a total of 116. Soil analysis also revealed that mixed conifer was significantly lower in pH, but higher in organic matter, potassium, phosphorus, and ammonium when compared to lodgepole pine stands. Species richness per core was correlated with these chemical data, however, analysis of covariance indicated that stand type was the only statistically significant factor in the observed difference in species richness. Our data suggest that ECM fungal richness increases as homogenous lodgepole pine stands grow and mature, but declines after Engelmann spruce and subalpine fir colonize. Despite difficulties linking species composition with soil chemistry, there are a variety of physical and chemical factors that could be influencing ECM community structure. Future field experiments are necessary to test some of the mechanisms potentially operating

  6. Fire regimes, forest change, and self-organization in an old-growth mixed-conifer forest, Yosemite National Park, USA.

    PubMed

    Scholl, Andrew E; Taylor, Alan H

    2010-03-01

    Fire is recognized as a keystone process in dry mixed-conifer forests that have been altered by decades of fire suppression, Restoration of fire disturbance to these forests is a guiding principle of resource management in the U.S. National Park Service. Policy implementation is often hindered by a poor understanding of forest conditions before fire exclusion, the characteristics of forest changes since excluding fire, and the influence of topographic or self-organizing controls on forest structure. In this study the spatial and temporal characteristics of fire regimes and forest structure are reconstructed in a 2125-ha mixed-conifer forest. Forests were multi-aged, burned frequently at low severity and fire-return interval, and forest structure did not vary with slope aspect, elevation, or slope position. Fire exclusion has caused an increase in forest density and basal area and a compositional shift to shade-tolerant and fire-intolerant species. The median point fire-return interval and extent of a fire was 10 yr and 115 ha, respectively. The pre-Euro-American settlement fire rotation of 13 yr increased to 378 yr after 1905. The position of fire scars within tree rings indicates that 79% of fires burned in the midsummer to fall period. The spatial pattern of burns exhibited self-organizing behavior. Area burned was 10-fold greater when an area had not been burned by the previous fire. Fires were frequent and widespread, but patches of similar aged trees were < 0.2 ha, suggesting small fire-caused canopy openings. Managers need to apply multiple burns at short intervals for a sustained period to reduce surface fuels and create small canopy openings characteristic of the reference forest. By coupling explicit reference conditions with consideration of current conditions and projected climate change, management activities can balance restoration and risk management.

  7. Species-specific and seasonal differences in chlorophyll fluorescence and photosynthetic light response among three evergreen species in a Madrean sky island mixed conifer forest

    NASA Astrophysics Data System (ADS)

    Potts, D. L.; Minor, R. L.; Braun, Z.; Barron-Gafford, G. A.

    2012-12-01

    Unlike the snowmelt-dominated hydroclimate of more northern mountainous regions, the hydroclimate of the Madrean sky islands is characterized by snowmelt and convective storms associated with the North American Monsoon. These mid-summer storms trigger biological activity and are important drivers of primary productivity. For example, at the highest elevations where mixed conifer forests occur, ecosystem carbon balance is influenced by monsoon rains. Whereas these storms' significance is increasingly recognized at the ecosystem scale, species-specific physiological responses to the monsoon are poorly known. Prior to and following monsoon onset, we measured pre-dawn and light-adapted chlorophyll fluorescence as well as photosynthetic light response in southwestern white pine (Pinus strobiformis), ponderosa pine (Pinus ponderosa), and Douglas fir (Pseudotsuga menziesii) in a Madrean sky island mixed conifer forest near Tucson, Arizona. Photochemical quenching (qp), an indicator of the proportion of open PSII reaction centers, was greatest in P. strobiformis and least in P. menziesii and increased in response to monsoon rains (repeated-measures ANOVA; species, F2,14 = 6.17, P = 0.012; time, F2,14= 8.17, P = 0.013). In contrast, non-photochemical quenching (qN), an indicator of heat dissipation ability, was greatest in P. ponderosa and least in P. menziesii, but was not influenced by monsoon onset (repeated-measures ANOVA; species, F2,12 = 4.18, P = 0.042). Estimated from leaf area-adjusted photosynthetic light response curves, maximum photosynthetic rate (Amax) was greatest in P. ponderosa and least in P. menziesii (repeated-measures ANOVA; species, F2,8= 40.8, P = 0.001). Surprisingly, while the monsoon positively influenced Amax among P. ponderosa and P. strobiformis, Amax of P. menziesii declined with monsoon onset (repeated-measures ANOVA; species x time, F2,8 = 13.8, P = 0.002). Calculated as the initial slope of the photosynthetic light response curve, light

  8. Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring.

    PubMed

    Fréchette, Emmanuelle; Wong, Christopher Y S; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

    2015-12-01

    In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI-LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures.

  9. Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring

    PubMed Central

    Fréchette, Emmanuelle; Wong, Christopher Y. S.; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

    2015-01-01

    In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI–LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. PMID:26386258

  10. High-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and gas chromatography-flame ionization detection characterization of Delta5-polyenoic fatty acids in triacylglycerols from conifer seed oils.

    PubMed

    Lísa, Miroslav; Holcapek, Michal; Rezanka, Tomás; Kabátová, Nadezda

    2007-03-30

    Edible conifer seeds can serve as a source of triacylglycerols (TGs) with unusual Delta5 unsaturated polymethylene interrupted fatty acids (UPIFAs), such as cis-5,9-octadecadienoic (taxoleic), cis-5,9,12-octadecatrienoic (pinolenic), cis-5,11-eicosadienoic (keteleeronic) and cis-5,11,14-eicosatrienoic acids (sciadonic). Conifer seed oils from European Larch (Larix decidua), Norway Spruce (Picea abies) and European Silver Fir (Abies alba) have been analyzed by non-aqueous reversed-phase high-performance liquid chromatography (NARP-HPLC) with atmospheric pressure chemical ionisation (APCI)-MS detection. The influence of different positions of double bonds in Delta5-UPIFAs on the retention and fragmentation behavior is described and used for the successful identification of TGs in each oil. TGs containing Delta5-UPIFAs have a higher retention in comparison with common TGs found in plant oils with single methylene interrupted Delta6(9)-FAs and also significantly changed relative abundances of fragment ions in APCI mass spectra. Results obtained from HPLC/MS analyses are supported by validated GC/FID analyses of fatty acid methyl esters after the transesterification. The total content of Delta5-UPIFAs is about 32% for European Larch, 27% for Norway Spruce and 20% for European Silver Fir. In total, 20 FAs with acyl chain lengths from 16 to 24 carbon atoms and from 0 to 3 double bonds have been identified in 64 triacylglycerols from 3 conifer seed oils. PMID:17307191

  11. Stable Carbon Isotope Composition and Stomatal Density of the Conifer Genus Frenelopsis: Effect of pCO2, Species and Soil Salinity

    NASA Astrophysics Data System (ADS)

    Aucour, A.; Gomez, B.; Thevenard, F.; Sheppard, S.

    2004-05-01

    Experimental studies indicate that some modern conifers adjust their stomatal numbers in response to variations of atmospheric pCO2, suggesting that fossil conifer leaves may provide a proxy of pCO2. The stable carbon isotope composition of plants provides an additional constraint on the conditions during plant growth as it is known to vary, for a single species, with the δ 13C of the source CO2, and environmental factors such as soil salinity and water content. Our objectives were to document the variation of the stable carbon isotope composition of the fossil Coniferale Frenelopsis through the Cretaceous and to decipher the effect of pCO2, environmental and genetic factors on the fossil record. The leaf cuticles of Frenelopsis present a large variation in δ 13C values from 27 ‰ for F. ugnaensis growing on freshwater lake shores to 21 ‰ for species growing on brackish to marine environments. The species growing on freshwater lake shore presents an increase in 13C through the Barremian that is consistent with an increase in aridity. It presents a low stomatal density (SD) and index (SI: stomates over stomates plus epidermal cells). Comparison of the SD and SI within a single population shows that the variability in SD essentially reflects that of the cellular size and growth rate. The δ 13C values of species growing in brackish to marine environment are all similar but higher than freshwater ones in the late Albian. They decrease in the Cenomanian, with a much larger intra-population variability. This shift can be related to a switch from marine to brackish conditions as well as to more global change. SD and SI are higher for the late Albian-Cenomanian cuticles and appear not sensitive to the environmental change (presumably a switch from marine to more brackish conditions) recorded in the δ 13C. The large variability in both SD and SI within the studied populations in the marine-brackish environment appears to be related to change in the stomates over

  12. Mountain pine beetle-caused mortality over eight years in two pine hosts in mixed conifer stands of the southern Rocky Mountains

    USGS Publications Warehouse

    West, Daniel R.; Briggs, Jennifer S.; Jacobi, William R.; Negrón, José F.

    2014-01-01

    Eruptive mountain pine beetle (Dendroctonus ponderosae, MPB) populations have caused widespread mortality of pines throughout western North America since the late 1990s. Early work by A.D. Hopkins suggested that when alternate host species are available, MPB will prefer to breed in the host to which it has become adapted. In Colorado, epidemic MPB populations that originated in lodgepole pine expanded into mixed-conifer stands containing ponderosa pine, a related host. We evaluated the susceptibility of both hosts to successful MPB colonization in a survey of 19 sites in pine-dominated mixed-conifer stands spanning 140 km of the Front Range, CO, USA. In each of three 0.2-ha plots at each site, we (1) assessed trees in the annual flights of 2008–2011 to compare MPB-caused mortality between lodgepole and ponderosa pine; (2) recorded previous MPB-caused tree mortality from 2004–2007 to establish baseline mortality levels; and (3) measured characteristics of the stands (e.g. tree basal area) and sites (e.g. elevation, aspect) that might be correlated with MPB colonization. Uninfested average live basal area of lodgepole and ponderosa pine was 74% of total basal area before 2004. We found that for both species, annual percent basal area of attacked trees was greatest in one year (2009), and was lower in all other years (2004–2007, 2008, 2010, and 2011). Both pine species had similar average total mortality of 38–39% by 2011. Significant predictors of ponderosa pine mortality in a given year were basal area of uninfested ponderosa pine and the previous year’s mortality levels in both ponderosa and lodgepole pine. Lodgepole pine mortality was predicted by uninfested basal areas of both lodgepole and ponderosa pine, and the previous year’s lodgepole pine mortality. These results indicate host selection by MPB from lodgepole pine natal hosts into ponderosa pine the following year, but not the reverse. In both species, diameters of attacked trees within each year

  13. Incidence and effects of endemic populations of forest pests in young mixed-conifer forests of the Sierra Nevada. Forest Service research paper (Final)

    SciTech Connect

    Williams, C.B.; Azuma, D.L.; Ferrell, G.T.

    1992-05-01

    Approximately 3,200 trees in young mixed-conifer stands were examined for pest activity and human-caused or mechanical injuries, and approximately 25 percent of these trees were randomly selected for stem analyses. The examination of trees felled for stem analyses showed that 409 (47 percent) were free of pests and 466 (53 percent) had one or more pest categories. Incense-cedar contained the fewest number of pests with 133 out of 193 trees (69 percent) free of pests, and 60 trees or .31 percent with one or more pests. White fir and ponderosa pine trees had the highest percentage of pests and mechanical injuries: 64 percent (252 trees out of 395), and 62 percent (93 trees out of 151), respectively. Top injury and disease were the two most frequent pest/damage categories recorded among all tree species. White fir blister rust and cedar rust were the most frequent disease recorded on sugar pine and incense-cedar. Bark beetles were an important pest category for white fir, ponderosa pine, and incense-cedars.

  14. Applying microCT and 3D visualization to Jurassic silicified conifer seed cones: A virtual advantage over thin-sectioning1

    PubMed Central

    Gee, Carole T.

    2013-01-01

    • Premise of the study: As an alternative to conventional thin-sectioning, which destroys fossil material, high-resolution X-ray computed tomography (also called microtomography or microCT) integrated with scientific visualization, three-dimensional (3D) image segmentation, size analysis, and computer animation is explored as a nondestructive method of imaging the internal anatomy of 150-million-year-old conifer seed cones from the Late Jurassic Morrison Formation, USA, and of recent and other fossil cones. • Methods: MicroCT was carried out on cones using a General Electric phoenix v|tome|x s 240D, and resulting projections were processed with visualization software to produce image stacks of serial single sections for two-dimensional (2D) visualization, 3D segmented reconstructions with targeted structures in color, and computer animations. • Results: If preserved in differing densities, microCT produced images of internal fossil tissues that showed important characters such as seed phyllotaxy or number of seeds per cone scale. Color segmentation of deeply embedded seeds highlighted the arrangement of seeds in spirals. MicroCT of recent cones was even more effective. • Conclusions: This is the first paper on microCT integrated with 3D segmentation and computer animation applied to silicified seed cones, which resulted in excellent 2D serial sections and segmented 3D reconstructions, revealing features requisite to cone identification and understanding of strobilus construction. PMID:25202495

  15. Improving assessments of tropospheric ozone injury to Mediterranean montane conifer forests in California (USA) and Catalonia (Spain) with GIS models related to plant water relations

    NASA Astrophysics Data System (ADS)

    Kefauver, Shawn C.; Peñuelas, Josep; Ustin, Susan L.

    2012-12-01

    The impacts of tropospheric ozone on conifer health in the Sierra Nevada of California, USA, and the Pyrenees of Catalonia, Spain, were measured using field assessments and GIS variables of landscape gradients related to plant water relations, stomatal conductance and hence to ozone uptake. Measurements related to ozone injury included visible chlorotic mottling, needle retention, needle length, and crown depth, which together compose the Ozone Injury Index (OII). The OII values observed in Catalonia were similar to those in California, but OII alone correlated poorly to ambient ozone in all sites. Combining ambient ozone with GIS variables related to landscape variability of plant hydrological status, derived from stepwise regressions, produced models with R2 = 0.35, p = 0.016 in Catalonia, R2 = 0.36, p < 0.001 in Yosemite and R2 = 0.33, p = 0.007 in Sequoia/Kings Canyon National Parks in California. Individual OII components in Catalonia were modeled with improved success compared to the original full OII, in particular visible chlorotic mottling (R2 = 0.60, p < 0.001). The results show that ozone is negatively impacting forest health in California and Catalonia and also that modeling ozone injury improves by including GIS variables related to plant water relations.

  16. Data from camera surveys identifying co-occurrence and occupancy linkages between fishers (Pekania pennanti), rodent prey, mesocarnivores, and larger predators in mixed-conifer forests.

    PubMed

    Sweitzer, Rick A; Furnas, Brett J

    2016-03-01

    These data provide additional information relevant to the frequency of fisher detections by camera traps, and single-season occupancy and local persistence of fishers in small patches of forest habitats detailed elsewhere, "Landscape Fuel Reduction, Forest Fire, and Biophysical Linkages to Local Habitat Use and Local Persistence of Fishers (Pekania pennanti) in Sierra Nevada Mixed-conifer Forests" [10]. The data provides insight on camera trap detections of 3 fisher predators (bobcat [Lynx rufus]). Coyote [Canis latrans], mountain lion [Puma concolor], 5 mesocarnivores in the same foraging guild as fishers (gray fox [Urocyon cinereoargenteus]) ringtail [Bassariscus astutus], marten [Martes americana], striped skunk [Mephitis mephitis] spotted skunk [Spilogale gracilis], and 5 Sciuridae rodents that fishers consume as prey (Douglas squirrel [Tamiasciurus douglasii]), gray squirrel [Sciurus griseus], northern flying squirrel [Glaucomys sabrinus], long-eared chipmunk [Neotamias quadrimaculatus], California ground squirrel [Spermophilus beecheyi]. We used these data to identify basic patterns of co-occurrence with fishers, and to evaluate the relative importance of presence of competing mesocarnivores, rodent prey, and predators for fisher occupancy of small, 1 km(2) grid cells of forest habitat. PMID:26937448

  17. Comparison of lichen, conifer needles, passive air sampling devices, and snowpack as passive sampling media to measure semi-volatile organic compounds in remote atmospheres.

    PubMed

    Schrlau, Jill E; Geiser, Linda; Hageman, Kimberly J; Landers, Dixon H; Simonich, Staci Massey

    2011-12-15

    A wide range of semivolatile organic compounds (SOCs), including pesticides and polycyclic aromatic hydrocarbons (PAHs), were measured in lichen, conifer needles, snowpack and XAD-based passive air sampling devices (PASDs) collected from 19 different U.S. national parks in order to compare the magnitude and mechanism of SOC accumulation in the different passive sampling media. Lichen accumulated the highest SOC concentrations, in part because of its long (and unknown) exposure period, whereas PASDs accumulated the lowest concentrations. However, only the PASD SOC concentrations can be used to calculate an average atmospheric gas-phase SOC concentration because the sampling rates are known and the media is uniform. Only the lichen and snowpack SOC accumulation profiles were statistically significantly correlated (r = 0.552, p-value <0.0001) because they both accumulate SOCs present in the atmospheric particle-phase. This suggests that needles and PASDs represent a different composition of the atmosphere than lichen and snowpack and that the interpretation of atmospheric SOC composition is dependent on the type of passive sampling media used. All four passive sampling media preferentially accumulated SOCs with relatively low air-water partition coefficients, while snowpack accumulated SOCs with higher log K(OA) values compared to the other media. Lichen accumulated more SOCs with log K(OA) > 10 relative to needles and showed a greater accumulation of particle-phase PAHs.

  18. How do cold-sensitive species endure ice ages? Phylogeographic and paleodistribution models of postglacial range expansion of the mesothermic drought-tolerant conifer Austrocedrus chilensis.

    PubMed

    Souto, Cintia P; Kitzberger, Thomas; Arbetman, Marina P; Premoli, Andrea C

    2015-11-01

    In view of global climate change, it is important to understand the responses of tree species to climate changes in the past. Combinations of phylogeographic analysis of genetic evidence, coupled with species distribution models (SDMs), are improving our understanding on this subject. We combined SDMs and microsatellite data from populations of the entire range of Austrocedrus chilensis, a dominant mesotherm (cold-sensitive) conifer of dryland forests of the southern Andes, to test the hypothesis of long-distance postglacial migration from northern and warmer refugia at the Last Glacial Maximum (LGM). The SDM indicated suitable conditions for Austrocedrus in northern Chile (western) at the LGM and largely unsuitable conditions in Argentina (eastern). Population genetic diversity and effective population sizes within populations decreased southward along the Andes, consistent with the hypothesis of long-distance dispersal from a northern refugium. Results support the hypothesis of one (or a few) warmer (low latitude) refugia in Chile for Austrocedrus. On balance, the evidence suggests that in contrast to cold-tolerant tree taxa with the capacity to fast-track postglacial warming thanks to local refugia, cold-sensitive species might have undergone long-distance range expansion, lagging behind progressive climate change throughout the Holocene.

  19. Data from camera surveys identifying co-occurrence and occupancy linkages between fishers (Pekania pennanti), rodent prey, mesocarnivores, and larger predators in mixed-conifer forests

    PubMed Central

    Sweitzer, Rick A.; Furnas, Brett J.

    2016-01-01

    These data provide additional information relevant to the frequency of fisher detections by camera traps, and single-season occupancy and local persistence of fishers in small patches of forest habitats detailed elsewhere, “Landscape Fuel Reduction, Forest Fire, and Biophysical Linkages to Local Habitat Use and Local Persistence of Fishers (Pekania pennanti) in Sierra Nevada Mixed-conifer Forests” [10]. The data provides insight on camera trap detections of 3 fisher predators (bobcat [Lynx rufus]). Coyote [Canis latrans], mountain lion [Puma concolor], 5 mesocarnivores in the same foraging guild as fishers (gray fox [Urocyon cinereoargenteus]) ringtail [Bassariscus astutus], marten [Martes americana], striped skunk [Mephitis mephitis] spotted skunk [Spilogale gracilis], and 5 Sciuridae rodents that fishers consume as prey (Douglas squirrel [Tamiasciurus douglasii]), gray squirrel [Sciurus griseus], northern flying squirrel [Glaucomys sabrinus], long-eared chipmunk [Neotamias quadrimaculatus], California ground squirrel [Spermophilus beecheyi]. We used these data to identify basic patterns of co-occurrence with fishers, and to evaluate the relative importance of presence of competing mesocarnivores, rodent prey, and predators for fisher occupancy of small, 1 km2 grid cells of forest habitat. PMID:26937448

  20. Chernobyl doses. Volume 2. Conifer stress near chernobyl derived from landsat imagery. Technical report, 29 September 1987-28 February 1992

    SciTech Connect

    McClellan, G.E.; Hemmer, T.H.; DeWitt, R.N.

    1992-12-01

    This volume presents Landsat Thematic Mapper imagery of the area surrounding the Chernobyl Nuclear Reactor Station and derives quantitative estimates of the spatial extent and time progression of stress on coniferous forests resulting from the 26 April 1986 reactor explosion and release of radioactive material. Change detection between pre- and postaccident images demonstrates convincingly that remote sensing of the spectral reflectance of coniferous forests in visible and infrared wavelengths at moderate spatial resolution (30 meters) will detect the effects of large radiation doses to the forest canopy. This work was initiated at a time when the expectation for direct data from the Soviet Union on local, accident-induced radiation levels was limited and the satellite data provided an alternative source. Although information exchange with the former Soviet Union has improved dramatically, the results of this report are important, since they prove the feasibility of large-scale, spectral response measurements on radiation-exposed pine trees in a natural environment. Volume 1 presents the derivation of radiation doses from the imagery reviewed in this volume, describes changes in spectral reflectivity of the affected trees as a function of dose and time, and discusses the military operational implications of these results....Chernobyl, Forest damage, Landsat, Change detection, Conifer stress.

  1. Pit membrane structure is highly variable and accounts for a major resistance to water flow through tracheid pits in stems and roots of two boreal conifer species.

    PubMed

    Schulte, Paul J; Hacke, Uwe G; Schoonmaker, Amanda L

    2015-10-01

    The flow of xylem sap in conifers is strongly dependent on the presence of a low resistance path through bordered pits, particularly through the pores present in the margo of the pit membrane. A computational fluid dynamics approach was taken, solving the Navier-Stokes equation for models based on the geometry of pits observed in tracheids from stems and roots of Picea mariana (black spruce) and Picea glauca (white spruce). Model solutions demonstrate a close, inverse relationship between the total resistance of bordered pits and the total area of margo pores. Flow through the margo was dominated by a small number of the widest pores. Particularly for pits where the margo component of flow resistance was low relative to that of the torus, pore location near the inner edge of the margo allowed for greater flow than that occurring through similar-sized pores near the outer edge of the margo. Results indicate a surprisingly large variation in pit structure and flow characteristics. Nonetheless, pits in roots have lower resistance to flow than those in stems because the pits were wider and consisted of a margo with a larger area in pores. PMID:25944400

  2. Relating the temporal change observed by AIRSAR to surface and canopy properties of mixed conifer and hardwood forests of northern Michigan

    NASA Technical Reports Server (NTRS)

    Dobson, M. Craig; Mcdonald, Kyle; Ulaby, Fawwaz T.; Sharik, Terry

    1991-01-01

    The mixed hardwood and conifer forests of northern Michigan were overflown by a 3-frequency airborne imaging radar in Apr. and Jul. 1990. A set of 10 x 10 km test sites near the University of Michigan Biological Station at Douglas Lake and within the Hiawatha National Forest in the upper peninsula of Michigan contained training stands representing the various forest species typical of forest communities across the ecotone between the coniferous boreal forest and mid-latitude hardwood and coniferous forests. The polarimetric radar data were externally calibrated to allow interdate comparisons. The Apr. flight was prior to bud-break of deciduous species and patchy snowcover was present. The Jul. flights occurred during and 2 days after heavy rain showers, and provide a unique opportunity to examine the differences in radar backscatter attributable to intercepted precipitation. Analyses show that there are significant changes in backscattering between biophysically dissimilar forest stands on any given date and also between dates for a given forest stand. These differences in backscattering can be related to moisture properties of the forest floor and the overlying canopy and also to the quantity and organizational structure of the above-ground biomass.

  3. Data from camera surveys identifying co-occurrence and occupancy linkages between fishers (Pekania pennanti), rodent prey, mesocarnivores, and larger predators in mixed-conifer forests.

    PubMed

    Sweitzer, Rick A; Furnas, Brett J

    2016-03-01

    These data provide additional information relevant to the frequency of fisher detections by camera traps, and single-season occupancy and local persistence of fishers in small patches of forest habitats detailed elsewhere, "Landscape Fuel Reduction, Forest Fire, and Biophysical Linkages to Local Habitat Use and Local Persistence of Fishers (Pekania pennanti) in Sierra Nevada Mixed-conifer Forests" [10]. The data provides insight on camera trap detections of 3 fisher predators (bobcat [Lynx rufus]). Coyote [Canis latrans], mountain lion [Puma concolor], 5 mesocarnivores in the same foraging guild as fishers (gray fox [Urocyon cinereoargenteus]) ringtail [Bassariscus astutus], marten [Martes americana], striped skunk [Mephitis mephitis] spotted skunk [Spilogale gracilis], and 5 Sciuridae rodents that fishers consume as prey (Douglas squirrel [Tamiasciurus douglasii]), gray squirrel [Sciurus griseus], northern flying squirrel [Glaucomys sabrinus], long-eared chipmunk [Neotamias quadrimaculatus], California ground squirrel [Spermophilus beecheyi]. We used these data to identify basic patterns of co-occurrence with fishers, and to evaluate the relative importance of presence of competing mesocarnivores, rodent prey, and predators for fisher occupancy of small, 1 km(2) grid cells of forest habitat.

  4. [Characteristics of dominant tree species stem sap flow and their relationships with environmental factors in a mixed conifer-broadleaf forest in Dinghushan, Guangdong Province of South China].

    PubMed

    Huang, De-Wei; Zhang, De-Qiang; Zhou, Guo-Yi; Liu, Shi-Zhong; Otieno, Dennis; Li, Yue-Lin

    2012-05-01

    By the method of Granier' s thermal dissipation probe, the stem sap flow density of four dominant tree species (Pinus massoniana, Castanopsis chinensis, Schima superba, and Machilus kwangtungensis) in a mixed conifer-broadleaf forest in Dinghushan Reserve of South China was continuously measured in the dry season (November) and wet season (July) in 2010, and the environmental factors including air temperature, relative humidity, and photosynthetically active radiation (PAR) were measured synchronically, aimed to study the characteristics of the stem sap flow of the tree species in response to environmental factors. During the dry and wet seasons, the diurnal changes of the stem sap flow velocity of the tree species all presented a typical single-peak curve, with high values in the daytime and low values in the nighttime. The average and maximum sap flow velocities and the daily sap flow flux of broad-leaved trees (C. chinensis, S. superba, and M. kwangtungensis) were significantly higher than those of coniferous tree (P. massoniana), and the maximum sap flow velocity of P. massoniana, C. valueschinensis, S. superba, and M. kwangtungensis was 29.48, 38.54, 51.67 and 58.32 g H2O x m(-2) x s(-1), respectively. A time lag was observed between the sap flow velocity and the diurnal variations of PAR, vapor pressure deficiency, and air temperature, and there existed significant positive correlations between the sap flow velocity and the three environmental factors. The PAR in wet season and the air temperature in dry season were the leading factors affecting the stem sap flow velocity of the dominant tree species.

  5. [Characteristics of dominant tree species stem sap flow and their relationships with environmental factors in a mixed conifer-broadleaf forest in Dinghushan, Guangdong Province of South China].

    PubMed

    Huang, De-Wei; Zhang, De-Qiang; Zhou, Guo-Yi; Liu, Shi-Zhong; Otieno, Dennis; Li, Yue-Lin

    2012-05-01

    By the method of Granier' s thermal dissipation probe, the stem sap flow density of four dominant tree species (Pinus massoniana, Castanopsis chinensis, Schima superba, and Machilus kwangtungensis) in a mixed conifer-broadleaf forest in Dinghushan Reserve of South China was continuously measured in the dry season (November) and wet season (July) in 2010, and the environmental factors including air temperature, relative humidity, and photosynthetically active radiation (PAR) were measured synchronically, aimed to study the characteristics of the stem sap flow of the tree species in response to environmental factors. During the dry and wet seasons, the diurnal changes of the stem sap flow velocity of the tree species all presented a typical single-peak curve, with high values in the daytime and low values in the nighttime. The average and maximum sap flow velocities and the daily sap flow flux of broad-leaved trees (C. chinensis, S. superba, and M. kwangtungensis) were significantly higher than those of coniferous tree (P. massoniana), and the maximum sap flow velocity of P. massoniana, C. valueschinensis, S. superba, and M. kwangtungensis was 29.48, 38.54, 51.67 and 58.32 g H2O x m(-2) x s(-1), respectively. A time lag was observed between the sap flow velocity and the diurnal variations of PAR, vapor pressure deficiency, and air temperature, and there existed significant positive correlations between the sap flow velocity and the three environmental factors. The PAR in wet season and the air temperature in dry season were the leading factors affecting the stem sap flow velocity of the dominant tree species. PMID:22919822

  6. Survival, growth and vulnerability to drought in fire refuges: implications for the persistence of a fire-sensitive conifer in northern Patagonia.

    PubMed

    Landesmann, Jennifer B; Gowda, Juan H; Garibaldi, Lucas A; Kitzberger, Thomas

    2015-12-01

    Fire severity and extent are expected to increase in many regions worldwide due to climate change. Therefore, it is crucial to assess the relative importance of deterministic vs. stochastic factors producing remnant vegetation to understand their function in the persistence of fire-sensitive plants. Vegetation remnants (areas within the landscape that have not burned for a considerable amount of time) may occur stochastically or in more predictable locations (fire refuges) where physical conditions decrease fire severity. Our aim was to determine if remnant forests of the fire-sensitive conifer Austrocedrus chilensis are associated with biophysical attributes that allow persistence in a fire-prone Patagonian landscape. We conducted a multi-scale approach, determining attributes of forest remnants and their surroundings (matrices) through remote sensing and field-based biophysical and functional characteristics, and quantifying how tree survival probability relates to microsite conditions. Trees within remnants displayed abundant fire scars, were twofold older and had threefold larger growth rates than matrix trees. Remnants were associated with high rocky cover and elevated topographical positions. Tree survival increased in hilltops, eastern aspects, and with sparse vegetation. Trees within remnants experienced severe reductions in growth during droughts. Our results suggest that A. chilensis remnants are mainly the result of refuges, where environmental conditions increase fire survival, but also increase susceptibility to drought. A trade-off between fire survival and drought vulnerability may imply that under increasing drought and fire severity, locations that in the past have served as refuges may reduce their ability to allow the persistence of fire-sensitive taxa. PMID:26334864

  7. Analysis of the impacts of major anion variations on surface water acidity particularly with regard to conifer harvesting: case studies from Wales and Northern England

    NASA Astrophysics Data System (ADS)

    Neal, C.; Reynolds, B.; Adamson, J. K.; Stevens, P. A.; Neal, M.; Harrow, M.; Hill, S.

    Data on the water quality of streams draining a range of acidic and acid sensitive, mainly afforested, upland catchments in mid- and north-Wales and northern-England are described to investigate the acidification effects of conifer harvesting in relation to natural variability. Most sites show a large range in pH and major cation and major anion concentrations. The waters draining from the smaller catchments are more acidic and aluminium bearing reflecting a higher proportion of runoff from the acidic soils in each area. However, there is often a less acidic component of runoff under base-flow conditions due to ground-water contributions particularly within the larger streams. Higher concentrations of nitrate occur for sites which have been felled although declines in concentration occur several years after felling. Multiple regression analysis reveals the importance of cation exchange and within catchment acidification associated with sulphate and nitrate generation. Sulphate also has a component associated with weathering but the patterns vary from catchment to catchment. Analysis of the influence of changing anion concentrations associated with tree harvesting reveals that the acidification induced by increases in nitrate can be offset or reversed by the lowering of chloride and sulphate concentrations due to decreased atmospheric scavenging by the vegetation, reduced evapotranspiration and increased surface runoff diluting the acidity generated. It is concluded that contemporary UK forestry guidelines with an emphasis on phased harvesting of catchments over several years and careful harvesting methodologies can alleviate most problems of stream acidification associated with felling activities and in some cases can reverse the acidification pattern.

  8. Evolution of Diterpene Metabolism: Sitka Spruce CYP720B4 Catalyzes Multiple Oxidations in Resin Acid Biosynthesis of Conifer Defense against Insects1[C][W][OA

    PubMed Central

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-01-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism. PMID:21994349

  9. Effects of simulated acid rain on soil respiration and its components in a subtropical mixed conifer and broadleaf forest in southern China.

    PubMed

    Liang, Guohua; Hui, Dafeng; Wu, Xiaoying; Wu, Jianping; Liu, Juxiu; Zhou, Guoyi; Zhang, Deqiang

    2016-02-01

    Soil respiration is a major pathway in the global carbon cycle and its response to environmental changes is an increasing concern. Here we explored how total soil respiration (RT) and its components respond to elevated acid rain in a mixed conifer and broadleaf forest, one of the major forest types in southern China. RT was measured twice a month in the first year under four treatment levels of simulated acid rain (SAR: CK, the local lake water, pH 4.7; T1, water pH 4.0; T2, water pH 3.25; and T3, water pH 2.5), and in the second year, RT, litter-free soil respiration (RS), and litter respiration (RL) were measured simultaneously. The results indicated that the mean rate of RT was 2.84 ± 0.20 μmol CO2 m(-2) s(-1) in the CK plots, and RS and RL contributed 60.7% and 39.3% to RT, respectively. SAR marginally reduced (P = 0.08) RT in the first year, but significantly reduced RT and its two components in the second year (P < 0.05). The negative effects were correlated with the decrease in soil microbial biomass and fine root biomass due to soil acidification under the SAR. The temperature coefficients (Q10) of RT and its two components generally decreased with increasing levels of the SAR, but only the decrease of RT and RL was significant (P < 0.05). In addition, the contribution of RL to RT decreased significantly under the SAR, indicating that RL was more sensitive to the SAR than RS. In the context of elevated acid rain, the decline trend of RT in the forests in southern China appears to be attributable to the decline of soil respiration in the litter layer. PMID:26755128

  10. Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

    PubMed Central

    Stevens, Jens T.; Safford, Hugh D.; North, Malcolm P.; Fried, Jeremy S.; Gray, Andrew N.; Brown, Peter M.; Dolanc, Christopher R.; Dobrowski, Solomon Z.; Falk, Donald A.; Farris, Calvin A.; Franklin, Jerry F.; Fulé, Peter Z.; Hagmann, R. Keala; Knapp, Eric E.; Miller, Jay D.; Smith, Douglas F.; Swetnam, Thomas W.; Taylor, Alan H.

    2016-01-01

    Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the “stand age” variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical “mixed-severity” fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data. PMID:27196621

  11. Evolution of diterpene metabolism: Sitka spruce CYP720B4 catalyzes multiple oxidations in resin acid biosynthesis of conifer defense against insects.

    PubMed

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-12-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism. PMID:21994349

  12. Survival, growth and vulnerability to drought in fire refuges: implications for the persistence of a fire-sensitive conifer in northern Patagonia.

    PubMed

    Landesmann, Jennifer B; Gowda, Juan H; Garibaldi, Lucas A; Kitzberger, Thomas

    2015-12-01

    Fire severity and extent are expected to increase in many regions worldwide due to climate change. Therefore, it is crucial to assess the relative importance of deterministic vs. stochastic factors producing remnant vegetation to understand their function in the persistence of fire-sensitive plants. Vegetation remnants (areas within the landscape that have not burned for a considerable amount of time) may occur stochastically or in more predictable locations (fire refuges) where physical conditions decrease fire severity. Our aim was to determine if remnant forests of the fire-sensitive conifer Austrocedrus chilensis are associated with biophysical attributes that allow persistence in a fire-prone Patagonian landscape. We conducted a multi-scale approach, determining attributes of forest remnants and their surroundings (matrices) through remote sensing and field-based biophysical and functional characteristics, and quantifying how tree survival probability relates to microsite conditions. Trees within remnants displayed abundant fire scars, were twofold older and had threefold larger growth rates than matrix trees. Remnants were associated with high rocky cover and elevated topographical positions. Tree survival increased in hilltops, eastern aspects, and with sparse vegetation. Trees within remnants experienced severe reductions in growth during droughts. Our results suggest that A. chilensis remnants are mainly the result of refuges, where environmental conditions increase fire survival, but also increase susceptibility to drought. A trade-off between fire survival and drought vulnerability may imply that under increasing drought and fire severity, locations that in the past have served as refuges may reduce their ability to allow the persistence of fire-sensitive taxa.

  13. Effects of simulated acid rain on soil respiration and its components in a subtropical mixed conifer and broadleaf forest in southern China.

    PubMed

    Liang, Guohua; Hui, Dafeng; Wu, Xiaoying; Wu, Jianping; Liu, Juxiu; Zhou, Guoyi; Zhang, Deqiang

    2016-02-01

    Soil respiration is a major pathway in the global carbon cycle and its response to environmental changes is an increasing concern. Here we explored how total soil respiration (RT) and its components respond to elevated acid rain in a mixed conifer and broadleaf forest, one of the major forest types in southern China. RT was measured twice a month in the first year under four treatment levels of simulated acid rain (SAR: CK, the local lake water, pH 4.7; T1, water pH 4.0; T2, water pH 3.25; and T3, water pH 2.5), and in the second year, RT, litter-free soil respiration (RS), and litter respiration (RL) were measured simultaneously. The results indicated that the mean rate of RT was 2.84 ± 0.20 μmol CO2 m(-2) s(-1) in the CK plots, and RS and RL contributed 60.7% and 39.3% to RT, respectively. SAR marginally reduced (P = 0.08) RT in the first year, but significantly reduced RT and its two components in the second year (P < 0.05). The negative effects were correlated with the decrease in soil microbial biomass and fine root biomass due to soil acidification under the SAR. The temperature coefficients (Q10) of RT and its two components generally decreased with increasing levels of the SAR, but only the decrease of RT and RL was significant (P < 0.05). In addition, the contribution of RL to RT decreased significantly under the SAR, indicating that RL was more sensitive to the SAR than RS. In the context of elevated acid rain, the decline trend of RT in the forests in southern China appears to be attributable to the decline of soil respiration in the litter layer.

  14. Model-based analysis on the relationship between production and tree-ring growth in Japanese conifer-hardwood mixed forests

    NASA Astrophysics Data System (ADS)

    Koide, D.; Ito, A.

    2015-12-01

    Forest productivity is a basic and important component of terrestrial material flow and its importance increases according to recent climate warming and the increase in atmospheric-CO2 concentrations. Forest productivity study progresses through measurement by eddy-covariance data from flux tower and prediction by terrestrial ecosystem models. However, flux tower observation has spatiotemporal bias and limitation. On the other hand, tree-ring data have a close connection with forest ecosystem productivity. Compared to flux tower observation, we can collect tree-ring data from a larger number of sites and longer time scales. Comparisons between tree-ring observation and model-estimated productivity is important to reveal underlying mechanisms of forest ecosystem productivity and growth in wide spatiotemporal scale. This study aimed at revealing the relationship between temporal changes in tree-ring data and estimated forest ecosystem productivity in Japanese conifer-hardwood mixed forest. We also addressed climatic bias in the relationship by comparing between sites at different climatic conditions. Tree-ring data of Sakhalin spruce (Picea glehnii) were obtained from the International Tree Ring Data Bank. Six sites on the Hokkaido island (northern island of Japan) were selected for the present analysis. The Vegetation Integrated SImulator for Trace gasses (VISIT) model was validated by comparing with carbon flux data from Asia flux network sites. Past climatic parameters were obtained from ERA-20C reanalysis data from the European Center for Medium-range Weather Forecasts. Correlation between basal area increment and net ecosystem productivity was highest in the coldest site but this correlation weakened in warmer sites. This result implies that long-term growth trend was mainly restricted by cold stress associated with productivity reduction in colder sites but this factor is less important and other factors exert influence in warmer sites.

  15. Two ways of legumin-precursor processing in conifers. Characterization and evolutionary relationships of Metasequoia cDNAs representing two divergent legumin gene subfamilies.

    PubMed

    Häger, K P; Wind, C

    1997-06-15

    Subunit monomers and oligomers of crystalloid-type legumins are major components of SDS-soluble fractions from Metasequoia glyptostroboides (Dawn redwood, Taxodiaceae) seed proteins. The subunits are made up of disulfide linked alpha-polypeptides and beta-polypeptides with molecular masses of 33 kDa and 23-25 kDa, respectively. Unusually for legumins, those from Metasequoia are glycosylated and the carbohydrate moieties are residing in the C-terminal region of the respective beta-polypeptides. A Metasequoia endosperm cDNA library has been constructed and legumin-encoding transcripts representing two divergent gene subfamilies have been characterized. Intersubfamily comparisons reveal 75% identity at the amino acid level and the values range from 53-35% when the legumin precursors deduced were compared with those from angiosperms. The predicted sequences together with data from amino acid sequencing prove that post-translational processing of Metasequoia prolegumins is directed to two different processing sites, each of them specific for one of the legumin subfamilies. The sites involved differ in their relative position and in the junction to be cleaved: Metasequoia legumin precursors MgLeg18 and MgLeg26 contain the conventional post-translational Asn-Gly processing site, which is generally regarded as highly conserved. In contrast, the MgLeg4 precursor is lacking this site and post-translational cleavage is directed to an unusual Asn-Thr processing site located in its hypervariable region, causing N-terminal extension of the beta-polypeptide relative to those hitherto known. Evidence is given that the unusual variant of processing also occurs in other conifers. Phylogenetic analysis reveals the precursors concerned as representatives of a distinct legumin subfamily, originating from duplication of an ancestral gene prior to or at the beginning of Taxodiaceae diversification.

  16. Drought-induced increase in water-use efficiency reduces secondary tree growth and tracheid wall thickness in a Mediterranean conifer.

    PubMed

    Olano, José Miguel; Linares, Juan Carlos; García-Cervigón, Ana I; Arzac, Alberto; Delgado, Antonio; Rozas, Vicente

    2014-09-01

    In order to understand the impact of drought and intrinsic water-use efficiency (iWUE) on tree growth, we evaluated the relative importance of direct and indirect effects of water availability on secondary growth and xylem anatomy of Juniperus thurifera, a Mediterranean anisohydric conifer. Dendrochronological techniques, quantitative xylem anatomy, and (13)C/(12)C isotopic ratio were combined to develop standardized chronologies for iWUE, BAI (basal area increment), and anatomical variables on a 40-year-long annually resolved series for 20 trees. We tested the relationship between iWUE and secondary growth at short-term (annual) and long-term (decadal) temporal scales to evaluate whether gains in iWUE may lead to increases in secondary growth. We obtained a positive long-term correlation between iWUE and BAI, simultaneously with a negative short-term correlation between them. Furthermore, BAI and iWUE were correlated with anatomical traits related to carbon sink or storage (tracheid wall thickness and ray parenchyma amount), but no significant correlation with conductive traits (tracheid lumen) was found. Water availability during the growing season significantly modulated tree growth at the xylem level, where growth rates and wood anatomical traits were affected by June precipitation. Our results are consistent with a drought-induced limitation of tree growth response to rising CO2, despite the trend of rising iWUE being maintained. We also remark the usefulness of exploring this relationship at different temporal scales to fully understand the actual links between iWUE and secondary growth dynamics. PMID:24958369

  17. Evolution of diterpene metabolism: Sitka spruce CYP720B4 catalyzes multiple oxidations in resin acid biosynthesis of conifer defense against insects.

    PubMed

    Hamberger, Björn; Ohnishi, Toshiyuki; Hamberger, Britta; Séguin, Armand; Bohlmann, Jörg

    2011-12-01

    Diterpene resin acids (DRAs) are specialized (secondary) metabolites of the oleoresin defense of conifers produced by diterpene synthases and cytochrome P450s of the CYP720B family. The evolution of DRA metabolism shares common origins with the biosynthesis of ent-kaurenoic acid, which is highly conserved in general (primary) metabolism of gibberellin biosynthesis. Transcriptome mining in species of spruce (Picea) and pine (Pinus) revealed CYP720Bs of four distinct clades. We cloned a comprehensive set of 12 different Sitka spruce (Picea sitchensis) CYP720Bs as full-length cDNAs. Spatial expression profiles, methyl jasmonate induction, and transcript enrichment in terpenoid-producing resin ducts suggested a role of CYP720B4 in DRA biosynthesis. CYP720B4 was characterized as a multisubstrate, multifunctional enzyme by the formation of oxygenated diterpenoids in metabolically engineered yeast, yeast in vivo transformation of diterpene substrates, in vitro assays with CYP720B4 protein produced in Escherichia coli, and alteration of DRA profiles in RNA interference-suppressed spruce seedlings. CYP720B4 was active with 24 different diterpenoid substrates, catalyzing consecutive C-18 oxidations in the biosynthesis of an array of diterpene alcohols, aldehydes, and acids. CYP720B4 was most active in the formation of dehydroabietic acid, a compound associated with insect resistance of Sitka spruce. We identified patterns of convergent evolution of CYP720B4 in DRA metabolism and ent-kaurene oxidase CYP701 in gibberellin metabolism and revealed differences in the evolution of specialized and general diterpene metabolism in a gymnosperm. The genomic and functional characterization of the gymnosperm CYP720B family highlights that the evolution of specialized metabolism involves substantial diversification relative to conserved, general metabolism.

  18. Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America.

    PubMed

    Stevens, Jens T; Safford, Hugh D; North, Malcolm P; Fried, Jeremy S; Gray, Andrew N; Brown, Peter M; Dolanc, Christopher R; Dobrowski, Solomon Z; Falk, Donald A; Farris, Calvin A; Franklin, Jerry F; Fulé, Peter Z; Hagmann, R Keala; Knapp, Eric E; Miller, Jay D; Smith, Douglas F; Swetnam, Thomas W; Taylor, Alan H

    2016-01-01

    Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical "mixed-severity" fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data.

  19. The Imprint of Extreme Climate Events in Century-Long Time Series of Wood Anatomical Traits in High-Elevation Conifers

    PubMed Central

    Carrer, Marco; Brunetti, Michele; Castagneri, Daniele

    2016-01-01

    Extreme climate events are of key importance for forest ecosystems. However, both the inherent infrequency, stochasticity and multiplicity of extreme climate events, and the array of biological responses, challenges investigations. To cope with the long life cycle of trees and the paucity of the extreme events themselves, our inferences should be based on long-term observations. In this context, tree rings and the related xylem anatomical traits represent promising sources of information, due to the wide time perspective and quality of the information they can provide. Here we test, on two high-elevation conifers (Larix decidua and Picea abies sampled at 2100 m a.s.l. in the Eastern Alps), the associations among temperature extremes during the growing season and xylem anatomical traits, specifically the number of cells per ring (CN), cell wall thickness (CWT), and cell diameter (CD). To better track the effect of extreme events over the growing season, tree rings were partitioned in 10 sectors. Climate variability has been reconstructed, for 1800–2011 at monthly resolution and for 1926–2011 at daily resolution, by exploiting the excellent availability of very long and high quality instrumental records available for the surrounding area, and taking into account the relationship between meteorological variables and site topographical settings. Summer temperature influenced anatomical traits of both species, and tree-ring anatomical profiles resulted as being associated to temperature extremes. Most of the extreme values in anatomical traits occurred with warm (positive extremes) or cold (negative) conditions. However, 0–34% of occurrences did not match a temperature extreme event. Specifically, CWT and CN extremes were more clearly associated to climate than CD, which presented a bias to track cold extremes. Dendroanatomical analysis, coupled to high-quality daily-resolved climate records, seems a promising approach to study the effects of extreme events on

  20. Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America.

    PubMed

    Stevens, Jens T; Safford, Hugh D; North, Malcolm P; Fried, Jeremy S; Gray, Andrew N; Brown, Peter M; Dolanc, Christopher R; Dobrowski, Solomon Z; Falk, Donald A; Farris, Calvin A; Franklin, Jerry F; Fulé, Peter Z; Hagmann, R Keala; Knapp, Eric E; Miller, Jay D; Smith, Douglas F; Swetnam, Thomas W; Taylor, Alan H

    2016-01-01

    Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical "mixed-severity" fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data. PMID:27196621

  1. Photochemical smog effects in mixed conifer forests along a natural gradient of ozone and nitrogen deposition in the San Bernardino Mountains.

    PubMed

    Arbaugh, Michael; Bytnerowicz, Andrzej; Grulke, Nancy; Fenn, Mark; Poth, Mark; Temple, Patrick; Miller, Paul

    2003-06-01

    Toxic effects of photochemical smog on ponderosa and Jeffrey pines in the San Bernardino Mountains were discovered in the 1950s. It was revealed that ozone is the main cause of foliar injury manifested as chlorotic mottle and premature needle senescence. Various morphological, physiological and biochemical alterations in the affected plants have been reported over a period of about 40 years of multidisciplinary research. Recently, the focus of research has shifted from studying the effects of ozone to multiple pollutant effects. Recent studies have indicated that the combination of ozone and nitrogen may alter biomass allocation in pines towards that of deciduous trees, accelerate litter accumulation, and increase carbon sequestration rates in heavily polluted forests. Further study of the effects of multiple pollutants, and their long-term consequences on the mixed conifer ecosystem, cannot be adequately done using the original San Bernardino Mountains Air Pollution Gradient network. To correct deficiencies in the design, the new site network is being configured for long-term studies on multiple air pollutant concentrations and deposition, physiological and biochemical changes in trees, growth and composition of over-story species, biogeochemical cycling including carbon cycling and sequestration, water quality, and biodiversity of forest ecosystems. Eleven sites have been re-established. A comparison of 1974 stand composition with data from 2000 stand composition indicate that significant changes in species composition have occurred at some sites with less change at other sites. Moist, high-pollution sites have experienced the greatest amount of forest change, while dryer low-pollution sites have experienced the least amount of stand change. In general, ponderosa pine had the lowest basal area increases and the highest mortality across the San Bernardino Mountains. PMID:12676233

  2. Photochemical smog effects in mixed conifer forests along a natural gradient of ozone and nitrogen deposition in the San Bernardino Mountains.

    PubMed

    Arbaugh, Michael; Bytnerowicz, Andrzej; Grulke, Nancy; Fenn, Mark; Poth, Mark; Temple, Patrick; Miller, Paul

    2003-06-01

    Toxic effects of photochemical smog on ponderosa and Jeffrey pines in the San Bernardino Mountains were discovered in the 1950s. It was revealed that ozone is the main cause of foliar injury manifested as chlorotic mottle and premature needle senescence. Various morphological, physiological and biochemical alterations in the affected plants have been reported over a period of about 40 years of multidisciplinary research. Recently, the focus of research has shifted from studying the effects of ozone to multiple pollutant effects. Recent studies have indicated that the combination of ozone and nitrogen may alter biomass allocation in pines towards that of deciduous trees, accelerate litter accumulation, and increase carbon sequestration rates in heavily polluted forests. Further study of the effects of multiple pollutants, and their long-term consequences on the mixed conifer ecosystem, cannot be adequately done using the original San Bernardino Mountains Air Pollution Gradient network. To correct deficiencies in the design, the new site network is being configured for long-term studies on multiple air pollutant concentrations and deposition, physiological and biochemical changes in trees, growth and composition of over-story species, biogeochemical cycling including carbon cycling and sequestration, water quality, and biodiversity of forest ecosystems. Eleven sites have been re-established. A comparison of 1974 stand composition with data from 2000 stand composition indicate that significant changes in species composition have occurred at some sites with less change at other sites. Moist, high-pollution sites have experienced the greatest amount of forest change, while dryer low-pollution sites have experienced the least amount of stand change. In general, ponderosa pine had the lowest basal area increases and the highest mortality across the San Bernardino Mountains.

  3. Physiological responses of three deciduous conifers (Metasequoia glyptostroboides, Taxodium distichum and Larix laricina) to continuous light: adaptive implications for the early Tertiary polar summer.

    PubMed

    Equiza, M Alejandra; Day, Michael E; Jagels, Richard

    2006-03-01

    Polar regions were covered with extensive forests during the Cretaceous and early Tertiary, and supported trees comparable in size and productivity to those of present-day temperate forests. With a winter of total or near darkness and a summer of continuous, low-angle illumination, these temperate, high-latitude forests were characterized by a light regime without a contemporary counterpart. Although maximum irradiances were much lower than at mid-latitudes, the 24-h photoperiod provided similar integrated light flux. Taxodium, Larix and Metasequoia, three genera of deciduous conifers that occurred in paleoarctic wet forests, have extant, closely related descendents. However, the contemporary relative abundance of these genera differs greatly from that in the paleoarctic. To provide insight into attributes that favor competitive success in a continuous-light environment, we subjected saplings of these genera to a natural photoperiod or a 24-h photoperiod and measured gas exchange, chlorophyll fluorescence, non-structural carbohydrate concentrations, biomass production and carbon allocation. Exposure to continuous light significantly decreased photosynthetic capacity and quantum efficiency of photosystem II in Taxodium and Larix, but had minimal influence in Metasequoia. In midsummer, foliar starch concentration substantially increased in both Taxodium and Larix saplings grown in continuous light, which may have contributed to end-product down-regulation of photosynthetic capacity. In contrast, Metasequoia allocated photosynthate to continuous production of new foliar biomass. This difference in carbon allocation may have provided Metasequoia with a two fold advantage in the paleoarctic by minimizing depression of photosynthetic capacity and increasing photosynthetic surface.

  4. The Imprint of Extreme Climate Events in Century-Long Time Series of Wood Anatomical Traits in High-Elevation Conifers.

    PubMed

    Carrer, Marco; Brunetti, Michele; Castagneri, Daniele

    2016-01-01

    Extreme climate events are of key importance for forest ecosystems. However, both the inherent infrequency, stochasticity and multiplicity of extreme climate events, and the array of biological responses, challenges investigations. To cope with the long life cycle of trees and the paucity of the extreme events themselves, our inferences should be based on long-term observations. In this context, tree rings and the related xylem anatomical traits represent promising sources of information, due to the wide time perspective and quality of the information they can provide. Here we test, on two high-elevation conifers (Larix decidua and Picea abies sampled at 2100 m a.s.l. in the Eastern Alps), the associations among temperature extremes during the growing season and xylem anatomical traits, specifically the number of cells per ring (CN), cell wall thickness (CWT), and cell diameter (CD). To better track the effect of extreme events over the growing season, tree rings were partitioned in 10 sectors. Climate variability has been reconstructed, for 1800-2011 at monthly resolution and for 1926-2011 at daily resolution, by exploiting the excellent availability of very long and high quality instrumental records available for the surrounding area, and taking into account the relationship between meteorological variables and site topographical settings. Summer temperature influenced anatomical traits of both species, and tree-ring anatomical profiles resulted as being associated to temperature extremes. Most of the extreme values in anatomical traits occurred with warm (positive extremes) or cold (negative) conditions. However, 0-34% of occurrences did not match a temperature extreme event. Specifically, CWT and CN extremes were more clearly associated to climate than CD, which presented a bias to track cold extremes. Dendroanatomical analysis, coupled to high-quality daily-resolved climate records, seems a promising approach to study the effects of extreme events on trees

  5. Effects of redox fluctuations on microbial community ecology post-wildfire in a high elevation mixed-conifer catchment in northern New Mexico.

    NASA Astrophysics Data System (ADS)

    Fairbanks, D.; Green, K.; Murphy, M. A.; Shepard, C.; Chorover, J.; Rich, V. I.; Gallery, R. E.

    2015-12-01

    Wildfires are increasing in size and severity across the western United States with impacts on regional biogeochemical cycling. The resiliency of resident soil microbial communities determines rates of nutrient transformations as well as forest structure and recovery. Redox conditions in soil determine metabolic activities of microorganisms, which first consume oxygen and a succession of alternative terminal electron acceptors to support growth and metabolism using a variety of carbon sources. Controls on redox zonation are largely unknown in dominantly oxic soils, and microbial community adaptation and response to fluctuations in redox potential in a sub-alpine forested post-disturbance catchment has not been studied. Previous work has shown that fluctuating or rising water tables result in redox-dynamic sites, which can be 'hot spots' of biogeochemical activity depending on landscape position. Fire-induced tree mortality results in altered hydrologic flow paths and decreased evapotranspiration, leading to potential for intensified hot spot activity. We are testing such coupling of microbial activity with fluctuations in redox status using field measurements and laboratory incubation experiments. The 2013 Thompson Ridge Fire in the Jemez River Basin (NM) Critical Zone Observatory provides a highly-contextualized opportunity to examine how disturbance regime affects changes in soil microbial community dynamics and fluctuations in reduction-oxidation potential (as quantified by continuous CZO measurements of O2, CO2 and Eh as a function of soil depth and landscape location). We hypothesize that areas of depositional convergence in the catchment, which have been shown to exhibit more reducing conditions, will host microbial communities that are better adapted to fluctuating redox conditions and exhibit a greater diversity in functional capabilities. In these mixed conifer forests we find shifts in redox potential status in relation to depth and topography where more

  6. Conifer defence against insects: microarray gene expression profiling of Sitka spruce (Picea sitchensis) induced by mechanical wounding or feeding by spruce budworms (Choristoneura occidentalis) or white pine weevils (Pissodes strobi) reveals large-scale changes of the host transcriptome.

    PubMed

    Ralph, Steven G; Yueh, Hesther; Friedmann, Michael; Aeschliman, Dana; Zeznik, Jeffrey A; Nelson, Colleen C; Butterfield, Yaron S N; Kirkpatrick, Robert; Liu, Jerry; Jones, Steven J M; Marra, Marco A; Douglas, Carl J; Ritland, Kermit; Bohlmann, Jörg

    2006-08-01

    Conifers are resistant to attack from a large number of potential herbivores or pathogens. Previous molecular and biochemical characterization of selected conifer defence systems support a model of multigenic, constitutive and induced defences that act on invading insects via physical, chemical, biochemical or ecological (multitrophic) mechanisms. However, the genomic foundation of the complex defence and resistance mechanisms of conifers is largely unknown. As part of a genomics strategy to characterize inducible defences and possible resistance mechanisms of conifers against insect herbivory, we developed a cDNA microarray building upon a new spruce (Picea spp.) expressed sequence tag resource. This first-generation spruce cDNA microarray contains 9720 cDNA elements representing c. 5500 unique genes. We used this array to monitor gene expression in Sitka spruce (Picea sitchensis) bark in response to herbivory by white pine weevils (Pissodes strobi, Curculionidae) or wounding, and in young shoot tips in response to western spruce budworm (Choristoneura occidentalis, Lepidopterae) feeding. Weevils are stem-boring insects that feed on phloem, while budworms are foliage feeding larvae that consume needles and young shoot tips. Both insect species and wounding treatment caused substantial changes of the host plant transcriptome detected in each case by differential gene expression of several thousand array elements at 1 or 2 d after the onset of treatment. Overall, there was considerable overlap among differentially expressed gene sets from these three stress treatments. Functional classification of the induced transcripts revealed genes with roles in general plant defence, octadecanoid and ethylene signalling, transport, secondary metabolism, and transcriptional regulation. Several genes involved in primary metabolic processes such as photosynthesis were down-regulated upon insect feeding or wounding, fitting with the concept of dynamic resource allocation in plant

  7. A conifer genomics resource of 200,000 spruce (Picea spp.) ESTs and 6,464 high-quality, sequence-finished full-length cDNAs for Sitka spruce (Picea sitchensis)

    PubMed Central

    Ralph, Steven G; Chun, Hye Jung E; Kolosova, Natalia; Cooper, Dawn; Oddy, Claire; Ritland, Carol E; Kirkpatrick, Robert; Moore, Richard; Barber, Sarah; Holt, Robert A; Jones, Steven JM; Marra, Marco A; Douglas, Carl J; Ritland, Kermit; Bohlmann, Jörg

    2008-01-01

    Background Members of the pine family (Pinaceae), especially species of spruce (Picea spp.) and pine (Pinus spp.), dominate many of the world's temperate and boreal forests. These conifer forests are of critical importance for global ecosystem stability and biodiversity. They also provide the majority of the world's wood and fiber supply and serve as a renewable resource for other industrial biomaterials. In contrast to angiosperms, functional and comparative genomics research on conifers, or other gymnosperms, is limited by the lack of a relevant reference genome sequence. Sequence-finished full-length (FL)cDNAs and large collections of expressed sequence tags (ESTs) are essential for gene discovery, functional genomics, and for future efforts of conifer genome annotation. Results As part of a conifer genomics program to characterize defense against insects and adaptation to local environments, and to discover genes for the production of biomaterials, we developed 20 standard, normalized or full-length enriched cDNA libraries from Sitka spruce (P. sitchensis), white spruce (P. glauca), and interior spruce (P. glauca-engelmannii complex). We sequenced and analyzed 206,875 3'- or 5'-end ESTs from these libraries, and developed a resource of 6,464 high-quality sequence-finished FLcDNAs from Sitka spruce. Clustering and assembly of 147,146 3'-end ESTs resulted in 19,941 contigs and 26,804 singletons, representing 46,745 putative unique transcripts (PUTs). The 6,464 FLcDNAs were all obtained from a single Sitka spruce genotype and represent 5,718 PUTs. Conclusion This paper provides detailed annotation and quality assessment of a large EST and FLcDNA resource for spruce. The 6,464 Sitka spruce FLcDNAs represent the third largest sequence-verified FLcDNA resource for any plant species, behind only rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana), and the only substantial FLcDNA resource for a gymnosperm. Our emphasis on capturing FLcDNAs and ESTs from c

  8. Does woodland encroachment impact water?: An ecohydrology study of western juniper (Juniperus occidentalis) and other semi-arid conifers in the western U.S.

    NASA Astrophysics Data System (ADS)

    Niemeyer, R. J.; Link, T. E.; Heinse, R.; Seyfried, M. S.; Flerchinger, G. N.; Klos, P. Z.

    2015-12-01

    Semi-arid conifer species including western juniper (Juniperus occidentalis) among other pinyon and juniper (P-J) species have expanded into grass and shrub-dominated landscapes in the western U.S. Despite the importance of land cover changes to hydrological fluxes in these water-limited systems, there have been few process-based ecohydrology studies of western juniper encroachment. Furthermore, many conclusions about the impact of P-J encroachment on streamflow are limited to several studies in the southwestern U.S. Our objectives are to: a) assess how western juniper will impact above-ground hydrological processes, b) assess how western juniper will alter below-ground hydrological processes, c) assess how changes in P-J cover alters deep drainage across diverse climates of the western U.S. To accomplish these objectives we used a combination of continuous lysimeter and soil moisture measurements, periodic snow surveys, electrical resistivity tomography (ERT) and electromagnetic induction (EMI) surveys, simulations with the Simultaneous Heat and Water (SHAW) model and broad, spatially-coarse simulations with the atmosphere-vegetation-soil component of the HBV model. Juniper trees by both intercepting snow and increasing below-canopy snow melt caused tree wells to form throughout the winter. These tree wells increased snow redistribution to the base of the trees. Soil moisture in the interspace dominated by sagebrush, forbes, and grasses drops early in the season, but late season soil moisture changes are moderated by juniper. There is evidence that junipers continue to transpire soil moisture both late into the summer and at up to 3 meters deep. HBV simulations revealed that the potential for increases in deep drainage with a change from P-J to grass cover is principally controlled by the timing instead of the total precipitation. Simulations confirm previous empirical studies that landscapes in monsoon-dominated climates of the southwestern U.S. show negligible

  9. ‘Natural background’ soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

    NASA Astrophysics Data System (ADS)

    Doerr, S. H.; Woods, S. W.; Martin, D. A.; Casimiro, M.

    2009-06-01

    SummarySoils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites ( n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by collecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were further analyzed for repellency using WDPT and contact angle ( θsl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species ( Pinus ponderosa, Pinus contorta, Picea engelmanii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long-unburnt conifer forest soils of the north-western USA

  10. Fuel reduction and coarse woody debris dynamics with early season and late season prescribed fire in a Sierra Nevada mixed conifer forest

    USGS Publications Warehouse

    Knapp, E.E.; Keeley, J.E.; Ballenger, E.A.; Brennan, T.J.

    2005-01-01

    Fire exclusion has led to an unnatural accumulation and greater spatial continuity of organic material on the ground in many forests. This material serves both as potential fuel for forest fires and habitat for a large array of forest species. Managers must balance fuel reduction to reduce wildfire hazard with fuel retention targets to maintain other forest functions. This study reports fuel consumption and changes to coarse woody debris attributes with prescribed burns ignited under different fuel moisture conditions. Replicated early season burn, late season burn, and unburned control plots were established in old-growth mixed conifer forest in Sequoia National Park that had not experienced fire for more than 120 years. Early season burns were ignited during June 2002 when fuels were relatively moist, and late season burns were ignited during September/October 2001 when fuels were dry. Fuel loading and coarse woody debris abundance, cover, volume, and mass were evaluated prior to and after the burns. While both types of burns reduced fuel loading, early season burns consumed significantly less of the total dead and down organic matter than late season burns (67% versus 88%). This difference in fuel consumption between burning treatments was significant for most all woody fuel components evaluated, plus the litter and duff layers. Many logs were not entirely consumed - therefore the number of logs was not significantly changed by fire - but burning did reduce log length, cover, volume, and mass. Log cover, volume, and mass were reduced to a lesser extent by early season burns than late season burns, as a result of higher wood moisture levels. Early season burns also spread over less of the ground surface within the burn perimeter (73%) than late season burns (88%), and were significantly patchier. Organic material remaining after a fire can dam sediments and reduce erosion, while unburned patches may help mitigate the impact of fire on fire-sensitive species by

  11. Effects of fire and post-fire salvage logging on avian communities in conifer-dominated forests of the western United States

    USGS Publications Warehouse

    Kotliar, N.B.; Hejl, S.J.; Hutto, R.L.; Saab, V.A.; Melcher, C.P.; McFadzen, M.E.

    2002-01-01

    Historically, fire was one of the most widespread natural disturbances in the western United States. More recently, however, significant anthropogenic activities, especially fire suppression and silvicultural practices, have altered fire regimes; as a result, landscapes and associated communities have changed as well. Herein, we review current knowledge of how fire and post-fire salvaging practices affect avian communities in conifer-dominated forests of the western United States. Specifically, we contrast avian communities in (1) burned vs. unburned forest, and (2) unsalvaged vs. salvage-logged burns. We also examine how variation in burn characteristics (e.g., severity, age, size) and salvage logging can alter avian communities in burns. Of the 41 avian species observed in three or more studies comparing early post-fire and adjacent unburned forests, 22% are consistently more abundant in burned forests, 34% are usually more abundant in unburned forests, and 44% are equally abundant in burned and unburned forests or have varied responses. In general, woodpeckers and aerial foragers are more abundant in burned forest, whereas most foliage-gleaning species are more abundant in unburned forests. Bird species that are frequently observed in stand-replacement burns are less common in understory burns; similarly, species commonly observed in unburned forests often decrease in abundance with increasing burn severity. Granivores and species common in open-canopy forests exhibit less consistency among studies. For all species, responses to fire may be influenced by a number of factors including burn severity, fire size and shape, proximity to unburned forests, pre- and post-fire cover types, and time since fire. In addition, post-fire management can alter species' responses to burns. Most cavity-nesting species do not use severely salvaged burns, whereas some cavity-nesters persist in partially salvaged burns. Early post-fire specialists, in particular, appear to prefer

  12. 'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

    USGS Publications Warehouse

    Doerr, S.H.; Woods, S.W.; Martin, D.A.; Casimiro, M.

    2009-01-01

    Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by collecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were further analyzed for repellency using WDPT and contact angle (??sl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelmanii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long-unburnt conifer forest soils of the north-western USA is

  13. Forest management for water: a hydro-ecological modeling exercise of headwater catchments in the mixed-conifer belt of the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Bales, R. C.; Ray, R. L.

    2011-12-01

    Hydro-ecological modeling provides a cost-effective method for evaluating the effects of vegetation change on water cycling within a catchment. In mountain watersheds, change in forest vegetation not only has direct effects on transpiration rates, but also energy exchanges that influence patterns of snow ablation. In this study, treatment scenarios were implemented using the Regional Hydro-Ecological Simulation System (RHESSys) to estimate impacts on key elements of the hydrologic cycle affected by forest harvesting - snowpack accumulation, ablation, transpiration, and streamflow. Twelve headwater catchments (0.5 - 2.6 km2, 1460 - 2450m) in the mixed-conifer zone of the central Sierra Nevada, within the Sierra and Tahoe National Forests, were included for analysis. These research sites are part of the Sierra Nevada Adaptive Management Project (SNAMP), located in the headwaters of the American and Merced Rivers, and the Southern Sierra Critical Zone Observatory (CZO) in the Kings River basin. Two methods of forest harvesting were simulated in the study watersheds: 1) uniform canopy thinning, through reduction of Leaf Area Index (LAI) values and 2) strip-cut treatments, suggested as the best method for retaining snowpack. Results from this study compare the influence of vegetation on water cycle dynamics through the two harvesting treatments, initial vegetation densities, and individual catchment size. Model simulations for pre-treatment snow depth, soil moisture, and streamflow were validated with SNAMP and CZO in-situ measurements. Preliminary results show that a linear reduction of forest canopy reduces transpiration accordingly, but produces a non-linear increase in streamflow. Peak discharges also increased, occurring earlier in the spring and having more pronounced effects in the smaller catchments. Based on these results, harvesting thresholds required for obtaining increases in water yield are evaluated. Investigating the impact of forest management on these

  14. Factors promoting larch dominance in central Siberia: fire versus growth performance and implications for carbon dynamics at the boundary of evergreen and deciduous conifers

    NASA Astrophysics Data System (ADS)

    Schulze, E.-D.; Wirth, C.; Mollicone, D.; von Lüpke, N.; Ziegler, W.; Achard, F.; Mund, M.; Prokushkin, A.; Scherbina, S.

    2012-04-01

    The relative role of fire and of climate in determining canopy species composition and aboveground carbon stocks were investigated. Measurements were made along a transect extending from the dark taiga zone of central Siberia, where Picea and Abies dominate the canopy, into the Larix zone of eastern Siberia. We test the hypotheses that the change in canopy species composition is based (1) on climate-driven performance only, (2) on fire only, or (3) on fire-performance interactions. We show that the evergreen conifers Picea obovata and Abies sibirica are the natural late-successional species both in central and eastern Siberia, provided there has been no fire for an extended period of time. There are no changes in performance of the observed species along the transect. Fire appears to be the main factor explaining the dominance of Larix and of soil carbon. Of lesser influence were longitude as a proxy for climate, local hydrology and active-layer thickness. We can only partially explain fire return frequency, which is not only related to climate and land cover, but also to human behavior. Stand-replacing fires decreased from 300 to 50 yrs between the Yenisei Ridge and the upper Tunguska. Repeated non-stand-replacing surface fires eliminated the regeneration of Abies and Picea. With every 100 yrs since the last fire, the percentage of Larix decreased by 20%. Biomass of stems of single trees did not show signs of age-related decline. Relative diameter increment was 0.41 ± 0.20% at breast height and stem volume increased linearly over time with a rate of about 0.36 t C ha-1 yr-1 independent of age class and species. Stand biomass reached about 130 t C ha-1(equivalent to about 520 m3 ha-1). Individual trees of Larix were older than 600 yrs. The maximum age and biomass seemed to be limited by fungal rot of heart wood. 60% of old Larix and Picea and 30% of Pinus sibirica trees were affected by stem rot. Implications for the future role of fire and of plant diseases are

  15. Hydrogen Apparent Fractionation between Precipitation and Leaf Wax n-Alkanes from Conifers and Deciduous Angiosperms along a Longitudinal Transect in Eurasia

    NASA Astrophysics Data System (ADS)

    Pedentchouk, Nikolai; Fisher, Katherine; Wagner, Thomas

    2010-05-01

    D/H composition of individual organic compounds derived from leaf wax may provide a wealth of information regarding plant-water relations in studies of plant ecology and climate change. Extracting that information from the organic D/H signal requires a thorough understanding of hydrogen isotope fractionation between environmental water and organic compounds. The purpose of this project is to investigate the importance of plant types and local climatic conditions on hydrogen apparent fractionation in higher terrestrial plants. We determined D/H composition of n-alkanes derived from leaf wax extracted from several extant plants representing common evergreen and deciduous conifer (Pinus and Larix) and deciduous angiosperm (Betula, Salix, and Sorbus) genera along a longitudinal transect from the UK to central Siberia at 10 different locations. These data were used to calculate the apparent fractionation factor (epsilon) between source water, estimated using the Online Isotopes in Precipitation Calculator, and n-alkanes. Our initial results show the following. First, we found large differences in the epsilon values among different genera at each location, e.g. Betula -63‰ vs. Salix -115‰ in Norwich, UK, and Betula -86‰ vs. Salix -146‰ in Novosibirsk, Russia. Assuming the plants at individual locations utilized soil water of very similar deltaD values, variations in the epsilon values are likely to be explained by differences in plant physiology and biochemistry. Second, we identified extensive shifts in the epsilon values in individual species along the transect from the UK to central Siberia, e.g. Betula -63‰ in Norwich vs. -104‰ in Zotino, Krasnoyarsk Krai, central Siberia and Salix -115‰ in Norwich vs. -164‰ in Sodankyla, Finland. With the exception of Sorbus, there is a positive relationship between the MAT (mean annual temperature) and epsilon values at locations above 2 °C MAT, suggesting a possible climatic effect on isotopic fractionation

  16. Remote detection of insect epidemics in conifers

    NASA Technical Reports Server (NTRS)

    Heller, R. C.

    1970-01-01

    With properly exposed color or infrared color film, discolored foliage caused by insect infestations in ponderosa pine is detectable on moderately small-scale photographs with acceptable accuracies. Black and white photographs which matched the wavebands of the ERTS multispectral scanner were combined into one additive color photo. This imagery was not as useful as photographs taken on color, color infrared, or color film with a minus blue filter. Based on the high-altitude color and color infrared photos obtained, it is concluded that only insect infestations larger than 100 meters in diameter are detectable on ERTS imagery.

  17. Conifer ovulate cones accumulate pollen principally by simple impaction

    PubMed Central

    Cresswell, James E.; Henning, Kevin; Pennel, Christophe; Lahoubi, Mohamed; Patrick, Michael A.; Young, Phillipe G.; Tabor, Gavin R.

    2007-01-01

    In many pine species (Family Pinaceae), ovulate cones structurally resemble a turbine, which has been widely interpreted as an adaptation for improving pollination by producing complex aerodynamic effects. We tested the turbine interpretation by quantifying patterns of pollen accumulation on ovulate cones in a wind tunnel and by using simulation models based on computational fluid dynamics. We used computer-aided design and computed tomography to create computational fluid dynamics model cones. We studied three species: Pinus radiata, Pinus sylvestris, and Cedrus libani. Irrespective of the approach or species studied, we found no evidence that turbine-like aerodynamics made a significant contribution to pollen accumulation, which instead occurred primarily by simple impaction. Consequently, we suggest alternative adaptive interpretations for the structure of ovulate cones. PMID:17986613

  18. Novel insights into regulation of asparagine synthetase in conifers.

    PubMed

    Canales, Javier; Rueda-López, Marina; Craven-Bartle, Blanca; Avila, Concepción; Cánovas, Francisco M

    2012-01-01

    Asparagine, a key amino acid for nitrogen storage and transport in plants, is synthesized via the ATP-dependent reaction catalyzed by the enzyme asparagine synthetase (AS; EC 6.3.5.4). In this work, we present the molecular analysis of two full-length cDNAs that encode asparagine synthetase in maritime pine (Pinus pinaster Ait.), PpAS1, and PpAS2. Phylogenetic analyses of the deduced amino acid sequences revealed that both genes are class II AS, suggesting an ancient origin of these genes in plants. A comparative study of PpAS1 and PpAS2 gene expression profiles showed that PpAS1 gene is highly regulated by developmental and environmental factors, while PpAS2 is expressed constitutively. To determine the molecular mechanisms underpinning the differential expression of PpAS1, the promoter region of the gene was isolated and putative binding sites for MYB transcription factors were identified. Gel mobility shift assays showed that a MYB protein from Pinus taeda (PtMYB1) was able to interact with the promoter region of PpAS1. Furthermore, transient expression analyses in pine cells revealed a negative effect of PtMYB1 on PpAS1 expression. The potential role of MYB factors in the transcriptional regulation of PpAS1 in vascular cells is discussed.

  19. Volatile diterpene emission from dominant conifers in Japan

    NASA Astrophysics Data System (ADS)

    Matsunaga, S. N.; Chatani, S.; Nakatsuka, S.; Kusumoto, D.; Kubota, K.; Utsumi, Y.; Enoki, T.; Tani, A.; Hiura, T.

    2011-07-01

    Reactive volatile organic compounds (VOCs) are known to affect atmospheric chemistry, especially biogenic VOCs (BVOCs) which have a significant impact on regional air quality due to their large emission rates and high reactivities. Diterpenes (Kaur-16-ene and a diterpene likely to be Hibaene) were detected in all of the 205 enclosure air samples collected over multiple seasons at two different sites from Cryptomeria japonica and Chamaecyparis obtusa trees, the dominant coniferous trees in Japan. The emission rate of Kaur-16-ene, was determined to be from 0.01 to 7.1 μg dwg-1 h-1 (average: 0.61 μg dwg-1 h-1) by branch enclosure measurements and solid phase - liquid extraction techniques. The emission rate was an order of magnitude higher than that of monoterpenes which are known to comprise a major portion of total BVOC emissions. In addition, total emission of Kaur-16-ene at 30 °C was estimated to be comparable to that of total anthropogenic VOC emissions. To our knowledge, this is the first report of volatile diterpene emissions from trees.

  20. The Conifers of the Northern Rockies. Bulletin, 1917, No. 53

    ERIC Educational Resources Information Center

    Kirkwood, J. F.

    1918-01-01

    The purpose of this bulletin is to enable persons not technically trained in botany to identify the coniferous species of the northern Rocky Mountain region lying within the United States. Forest trees of all kinds have interest for all people. Familiar and affection knowledge of them has culture value of a very fine kind. For the people of some…

  1. A new drought tipping point for conifer mortality

    NASA Astrophysics Data System (ADS)

    Kolb, Thomas E.

    2015-03-01

    (Huang et al 2015 Environ. Res. Lett. 10 024011) present a method for predicting mortality of ponderosa pine (Pinus ponderosa) and pinyon pine (Pinus edulis) in the Southwestern US during severe drought based on the relationship between the standardized precipitation-evapotranspiration index (SPEI) and annual tree ring growth. Ring growth was zero when SPEI for September to July was -1.64. The threshold SPEI of -1.64 was successful in distinguishing areas with high tree mortality during recent severe drought from areas with low mortality, and is proposed to be a tipping point of drought severity leading to tree mortality. Below, I discuss this work in more detail.

  2. Geometric-optical Modeling of a Conifer Forest Canopy

    NASA Technical Reports Server (NTRS)

    Strahler, A. H. (Principal Investigator)

    1985-01-01

    The objective of this research is to explore how the geometry of trees in forest stands influences the reflectance of the forest as imaged from space. Most plant canopy modeling has viewed the canopy as an assemblage of plane-parallel layers on top of a soil surface. For these models, leaf angle distribution, leaf area index, and the angular transmittance and reflectance of leaves are the primary optical and geometric parameters. Such models are now sufficiently well developed to explain most of the variance in angular reflectance measurements observed from homogeneous plant canopies. However, forest canopies as imaged by airborne and spaceborne scanners exhibit considerable variance at quite a different scale. Brightness values vary strongly from one pixel to the next primarily as a function of the number of trees they contain. At this scale, the forest canopy is nonuniform and discontinuous. This research focuses on a discrete-element, geometric-optical view of the forest canopy.

  3. Dynamics of leaf water relations components in co-occurring iso- and anisohydric conifer species.

    PubMed

    Meinzer, Frederick C; Woodruff, David R; Marias, Danielle E; McCulloh, Katherine A; Sevanto, Sanna

    2014-11-01

    Because iso- and anisohydric species differ in stomatal regulation of the rate and magnitude of fluctuations in shoot water potential, they may be expected to show differences in the plasticity of their shoot water relations components, but explicit comparisons of this nature have rarely been made. We subjected excised shoots of co-occurring anisohydric Juniperus monosperma and isohydric Pinus edulis to pressure-volume analysis with and without prior artificial rehydration. In J. monosperma, the shoot water potential at turgor loss (Ψ(TLP)) ranged from -3.4 MPa in artificially rehydrated shoots to -6.6 MPa in shoots with an initial Ψ of -5.5 MPa, whereas in P. edulis mean Ψ(TLP) remained at ∼ -3.0 MPa over a range of initial Ψ from -0.1 to -2.3 MPa. The shoot osmotic potential at full turgor and the bulk modulus of elasticity also declined sharply with shoot Ψ in J. monosperma, but not in P. edulis. The contrasting behaviour of J. monosperma and P. edulis reflects differences in their capacity for homeostatic regulation of turgor that may be representative of aniso- and isohydric species in general, and may also be associated with the greater capacity of J. monosperma to withstand severe drought. PMID:24661116

  4. Family differences in height growth and photosynthetic traits in three conifers.

    PubMed

    Marshall, J D; Rehfeldt, G E; Monserud, R A

    2001-07-01

    We investigated variation in height growth, gas exchange, chlorophyll fluorescence and leaf stable carbon isotope ratio among wind-pollinated progenies of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca), ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and western white pine (Pinus monticola Dougl. ex D. Don) from a small group of contiguous stands on the Priest River Experimental Forest in northern Idaho. Photosynthetic variables differed between height classes in the pines, but not in Douglas-fir. Among species and families, tall families of ponderosa pine regained photosynthetic capacity earliest in the spring and maintained it latest in the growing season. Tall families of western white pine had higher instantaneous water-use efficiencies and lower photosynthetic rates than short families on warm days in August. PMID:11470658

  5. A New Tool for Exploring Climate Change Induced Range Shifts of Conifer Species in China

    PubMed Central

    Kou, Xiaojun; Li, Qin; Beierkuhnlein, Carl; Zhao, Yiheng; Liu, Shirong

    2014-01-01

    It is inevitable that tree species will undergo considerable range shifts in response to anthropogenic induced climate change, even in the near future. Species Distribution Models (SDMs) are valuable tools in exploring general temporal trends and spatial patterns of potential range shifts. Understanding projections to future climate for tree species will facilitate policy making in forestry. Comparative studies for a large number of tree species require the availability of suitable and standardized indices. A crucial limitation when deriving such indices is the threshold problem in defining ranges, which has made interspecies comparison problematic until now. Here we propose a set of threshold-free indices, which measure range explosion (I), overlapping (O), and range center movement in three dimensions (Dx, Dy, Dz), based on fuzzy set theory (Fuzzy Set based Potential Range Shift Index, F-PRS Index). A graphical tool (PRS_Chart) was developed to visualize these indices. This technique was then applied to 46 Pinaceae species that are widely distributed and partly common in China. The spatial patterns of the modeling results were then statistically tested for significance. Results showed that range overlap was generally low; no trends in range size changes and longitudinal movements could be found, but northward and poleward movement trends were highly significant. Although range shifts seemed to exhibit huge interspecies variation, they were very consistent for certain climate change scenarios. Comparing the IPCC scenarios, we found that scenario A1B would lead to a larger extent of range shifts (less overlapping and more latitudinal movement) than the A2 and the B1 scenarios. It is expected that the newly developed standardized indices and the respective graphical tool will facilitate studies on PRS's for other tree species groups that are important in forestry as well, and thus support climate adaptive forest management. PMID:25268604

  6. Acid mist and ozone effects on the leaf chemistry of two western conifer species.

    PubMed

    Westman, W E; Temple, P J

    1989-01-01

    Seedlings of Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were more susceptible to leaf chemical changes following exposure to acid mist (pH 3.4-2.0) or acid mist/ozone combinations, than to ozone alone (0.1-0.2 microl/litre), when plants were exposed to alternating doses of these pollutants for 6-9 weeks. Under acid mist treatment, leaves exhibited higher levels of nitrogen and sulfur, two elements applied in acid mist. In addition, levels of foliar sodium, and, in the case of giant sequia, potassium, as well, increased under acid mist treatment. Iron and manganese were also mobilized, resulting in significant increases in these elements in pine, and decreases in manganese in giant sequoia foliage. The acid treatment also reduced chlorophyll b concentrations in pine, and, to a less significant extent, in giant sequoia. Calcium, magnesium, barium and strontium were differentially accumulated in giant sequoia compared to Jeffrey pine. Under acid mist treatment, all of these elements (except strontium) declined in concentration in giant sequoia, with calcium showing the most significant trend. The more extensive changes in leaf chemistry induced by acid mist are consistent with earlier observations of significant changes in spectral reflectance of these seedlings after 3 weeks of fumigation. Limited foliage samples collected from these two species in 1985 and 1986 in Sequoia/Kings Canyon National Parks in the southern Sierra Nevada do not in themselves indicate any clearcut or severe effects of ozone alone on leaf chemistry of these species, but a mild influence of nitrate-laden acid deposition, possibly in combination with ozone, is consistent with the rise in nitrogen and lignin levels in Jeffrey pine on sites observed to have moderate visible injury symptoms. No firm conclusions about effects of pollutants on leaf chemistry in these field sites is possible without further study.

  7. Subalpine conifers in different geographical locations host highly similar foliar bacterial endophyte communities.

    PubMed

    Carrell, Alyssa A; Carper, Dana L; Frank, A Carolin

    2016-08-01

    Pines in the subalpine environment at Niwot Ridge, CO, have been found to host communities of acetic acid bacteria (AAB) within their needles. The significance and ubiquity of this pattern is not known, but recent evidence of nitrogen (N)-fixing activity in Pinus flexilis (limber pine) foliage calls for a better understanding of the processes that regulate endophytic communities in forest tree canopies. Here, to test if AAB dominate the foliar bacterial microbiota in other subalpine locations, we compared the 16S rRNA community in needles from P. flexilis and P. contorta (lodgepole pine) growing in the Eastern Sierra Nevada, CA, and Niwot Ridge, CO. AAB made up the majority of the bacterial community in both species at both sites. Multiple distinct AAB taxa, resolved at the single nucleotide level, were shared across host species and sites, with dominant OTUs identical or highly similar to database sequences from cold environments, including high altitude air sampled in Colorado, and the endosphere of Arctic plants. Our results suggest strong selection for community composition, potentially amplified by the long lifespan of individual Pinus needles, along with low dispersal constraints on canopy bacteria. PMID:27267931

  8. Seasonal dynamics of mobile carbohydrate pools in phloem and xylem of two alpine timberline conifers.

    PubMed

    Gruber, A; Pirkebner, D; Oberhuber, W

    2013-10-01

    Recent studies on non-structural carbohydrate (NSC) reserves in trees focused on xylem NSC reserves, while still little is known about changes in phloem carbohydrate pools, where NSC charging might be significantly different. To gain insight on NSC dynamics in xylem and phloem, we monitored NSC concentrations in stems and roots of Pinus cembra (L.) and Larix decidua (Mill.) growing at the alpine timberline throughout 2011. Species-specific differences affected tree phenology and carbon allocation during the course of the year. After a delayed start in spring, NSC concentrations in L. decidua were significantly higher in all sampled tissues from August until the end of growing season. In both species, NSC concentrations were five to seven times higher in phloem than that in xylem. However, significant correlations between xylem and phloem starch content found for both species indicate a close linkage between long-term carbon reserves in both tissues. In L. decidua also, free sugar concentrations in xylem and phloem were significantly correlated throughout the year, while a lack of correlation between xylem and phloem free sugar pools in P. cembra indicate a decline of phloem soluble carbohydrate pools during periods of high sink demand.

  9. Synchronisms and correlations of spring phenology between apical and lateral meristems in two boreal conifers.

    PubMed

    Antonucci, Serena; Rossi, Sergio; Deslauriers, Annie; Lombardi, Fabio; Marchetti, Marco; Tognetti, Roberto

    2015-10-01

    Phenological synchronisms between apical and lateral meristems could clarify some aspects related to the physiological relationships among the different organs of trees. This study correlated the phenological phases of bud development and xylem differentiation during spring 2010-14 in balsam fir (Abies balsamea Mill.) and black spruce [(Picea mariana Mill. (BSP)] of the Monts-Valin National Park (Quebec, Canada) by testing the hypothesis that bud development occurs after the reactivation of xylem growth. From May to September, we conducted weekly monitoring of xylem differentiation using microcores and bud development with direct observations on terminal branches. Synchronism between the beginning of bud development and xylem differentiation was found in both species with significant correlations between the phases of bud and xylem phenology. Degree-day sum was more appropriate in assessing the date of bud growth resumption, while thermal thresholds were more suitable for cambium phenology. Our results provide new knowledge on the dynamics of spring phenology and novel information on the synchronisms between two meristems in coniferous trees. The study demonstrates the importance of precisely defining the phases of bud development in order to correctly analyse the relationships with xylem phenology. PMID:26377874

  10. Inhibition of insect glutathione S-transferase (GST) by conifer extracts.

    PubMed

    Wang, Zhiling; Zhao, Zhong; Abou-Zaid, Mamdouh M; Arnason, John T; Liu, Rui; Walshe-Roussel, Brendan; Waye, Andrew; Liu, Suqi; Saleem, Ammar; Cáceres, Luis A; Wei, Qin; Scott, Ian M

    2014-12-01

    Insecticide synergists biochemically inhibit insect metabolic enzyme activity and are used both to increase the effectiveness of insecticides and as a diagnostic tool for resistance mechanisms. Considerable attention has been focused on identifying new synergists from phytochemicals with recognized biological activities, specifically enzyme inhibition. Jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) BSP.), balsam fir (Abies balsamea (L.) Mill.), and tamarack larch (Larix laricina (Du Roi) Koch) have been used by native Canadians as traditional medicine, specifically for the anti-inflammatory and antioxidant properties based on enzyme inhibitory activity. To identify the potential allelochemicals with synergistic activity, ethanol crude extracts and methanol/water fractions were separated by Sephadex LH-20 chromatographic column and tested for in vitro glutathione S-transferase (GST) inhibition activity using insecticide-resistant Colorado potato beetle, Leptinotarsa decemlineata (Say) midgut and fat-body homogenate. The fractions showing similar activity were combined and analyzed by ultra pressure liquid chromatography-mass spectrometry. A lignan, (+)-lariciresinol 9'-p-coumarate, was identified from P. mariana cone extracts, and L. laricina and A. balsamea bark extracts. A flavonoid, taxifolin, was identified from P. mariana and P. banksiana cone extracts and L. laricina bark extracts. Both compounds inhibit GST activity with taxifolin showing greater activity compared to (+)-lariciresinol 9'-p-coumarate and the standard GST inhibitor, diethyl maleate. The results suggested that these compounds can be considered as potential new insecticide synergists. PMID:25270601

  11. Response of old-growth conifers to reduction in stand density in western Oregon forests

    USGS Publications Warehouse

    Latham, P.; Tappeiner, J. C.

    2002-01-01

    The positive growth response of healthy young trees to density reduction is well known. In contrast, large old trees are usually thought to be intrinsically limited in their ability to respond to increased growing space; therefore, density reduction is seldom used in stands of old-growth trees. We tested the null hypothesis that old-growth trees are incapable of responding with increased growth following density reduction. The diameter growth response of 271 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), ponderosa pine (Pinus ponderosa Dougl. ex Laws) and sugar pine (Pinus lambertiana Dougl.) trees ranging in age from 158 to 650 years was examined 20 to 50 years after density reduction. Density reduction involved either light thinning with removal of less vigorous trees, or shelterwood treatments in which overstory trees were not removed. Ratios of basal area growth after treatment to basal area growth before treatment, and several other measures of growth, all indicated that the old trees sometimes benefited and were not harmed by density reduction. Growth increased by 10% or more for 68% of the trees in treated stands, and nearly 30% of trees increased growth by over 50%. This growth response persisted for at least 20 years. During this 20-year period, only three trees in treated stands (1.5%) exhibited a rapid decrease in growth, whereas growth decreased in 64% of trees in untreated stands. The length of time before a growth response to density reduction occurred varied from 5 to 25 years, with the greatest growth response often occurring 20 to 25 years after treatment. These results have important implications both for the basic biology of aging in woody plants as well as for silvicultural practices in forests with old-growth trees.

  12. Dynamics of leaf water relations components in co-occurring iso- and anisohydric conifer species.

    PubMed

    Meinzer, Frederick C; Woodruff, David R; Marias, Danielle E; McCulloh, Katherine A; Sevanto, Sanna

    2014-11-01

    Because iso- and anisohydric species differ in stomatal regulation of the rate and magnitude of fluctuations in shoot water potential, they may be expected to show differences in the plasticity of their shoot water relations components, but explicit comparisons of this nature have rarely been made. We subjected excised shoots of co-occurring anisohydric Juniperus monosperma and isohydric Pinus edulis to pressure-volume analysis with and without prior artificial rehydration. In J. monosperma, the shoot water potential at turgor loss (Ψ(TLP)) ranged from -3.4 MPa in artificially rehydrated shoots to -6.6 MPa in shoots with an initial Ψ of -5.5 MPa, whereas in P. edulis mean Ψ(TLP) remained at ∼ -3.0 MPa over a range of initial Ψ from -0.1 to -2.3 MPa. The shoot osmotic potential at full turgor and the bulk modulus of elasticity also declined sharply with shoot Ψ in J. monosperma, but not in P. edulis. The contrasting behaviour of J. monosperma and P. edulis reflects differences in their capacity for homeostatic regulation of turgor that may be representative of aniso- and isohydric species in general, and may also be associated with the greater capacity of J. monosperma to withstand severe drought.

  13. δ18O in the Tropical Conifer Agathis robusta Records ENSO-Related Precipitation Variations

    PubMed Central

    Boysen, Bjorn M. M.; Evans, Michael N.; Baker, Patrick J.

    2014-01-01

    Long-lived trees from tropical Australasia are a potential source of information about internal variability of the El Niño-Southern Oscillation (ENSO), because they occur in a region where precipitation variability is closely associated with ENSO activity. We measured tree-ring width and oxygen isotopic composition (O) of -cellulose from Agathis robusta (Queensland Kauri) samples collected in the Atherton Tablelands, Queensland, Australia. Standard ring-width chronologies yielded low internal consistency due to the frequent presence of false ring-like anatomical features. However, in a detailed examination of the most recent 15 years of growth (1995–2010), we found significant correlation between O and local precipitation, the latter associated with ENSO activity. The results are consistent with process-based forward modeling of the oxygen isotopic composition of -cellulose. The O record also enabled us to confirm the presence of a false growth ring in one of the three samples in the composite record, and to determine that it occurred as a consequence of anomalously low rainfall in the middle of the 2004/5 rainy season. The combination of incremental growth and isotopic measures may be a powerful approach to development of long-term (150+ year) ENSO reconstructions from the terrestrial tropics of Australasia. PMID:25062034

  14. Mycorrhiza Reduces Adverse Effects of Dark Septate Endophytes (DSE) on Growth of Conifers

    PubMed Central

    Reininger, Vanessa; Sieber, Thomas N.

    2012-01-01

    Mycorrhizal roots are frequently colonized by fungi of the Phialocephala fortinii s.l. – Acephala applanata species complex (PAC). These ascomycetes are common and widespread colonizers of tree roots. Some PAC strains reduce growth increments of their hosts but are beneficial in protecting roots against pathogens. Nothing is known about the effects of PAC on mycorrhizal fungi and the PAC-mycorrhiza association on plant growth, even though these two fungal groups occur closely together in natural habitats. We expect reduced colonization rates and reduced negative effects of PAC on host plants if roots are co-colonized by an ectomycorrhizal fungus (ECM). Depending on the temperature regime interactions among the partners in this tripartite ECM-PAC-plant system might also change. To test our hypotheses, effects of four PAC genotypes (two pathogenic and two non-pathogenic on the Norway spruce), mycorrhization by Laccaria bicolor (strain S238N) and two temperature regimes (19°C and 25°C) on the biomass of the Douglas-fir (Pseudotsuga menziesii) and Norway spruce (Picea abies) seedlings were studied. Mycorrhization compensated the adverse effects of PAC on the growth of the Norway spruce at both temperatures. The growth of the Douglas-fir was not influenced either by PAC or mycorrhization at 19°C, but at 25°C mycorrhization had a similar protective effect as in the Norway spruce. The compensatory effects probably rely on the reduction of the PAC-colonization density by mycorrhizae. Temperature and the PAC strain only had a differential effect on the biomass of the Norway spruce but not on the Douglas-fir. Higher temperature reduced mycorrhization of both hosts. We conclude that ectomycorrhizae form physical and/or physiological barriers against PAC leading to reduced PAC-colonization of the roots. Additionally, our results indicate that global warming could cause a general decrease of mycorrhization making primary roots more accessible to other symbionts and pathogens. PMID:22900058

  15. EPICUTICULAR WAS COMPOSITIONS FOR PREDOMINANT CONIFERS OF WESTERN NORTH AMERICA. (R823990)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  16. Mycorrhiza reduces adverse effects of dark septate endophytes (DSE) on growth of conifers.

    PubMed

    Reininger, Vanessa; Sieber, Thomas N

    2012-01-01

    Mycorrhizal roots are frequently colonized by fungi of the Phialocephala fortinii s.l.-Acephala applanata species complex (PAC). These ascomycetes are common and widespread colonizers of tree roots. Some PAC strains reduce growth increments of their hosts but are beneficial in protecting roots against pathogens. Nothing is known about the effects of PAC on mycorrhizal fungi and the PAC-mycorrhiza association on plant growth, even though these two fungal groups occur closely together in natural habitats. We expect reduced colonization rates and reduced negative effects of PAC on host plants if roots are co-colonized by an ectomycorrhizal fungus (ECM). Depending on the temperature regime interactions among the partners in this tripartite ECM-PAC-plant system might also change. To test our hypotheses, effects of four PAC genotypes (two pathogenic and two non-pathogenic on the Norway spruce), mycorrhization by Laccaria bicolor (strain S238N) and two temperature regimes (19°C and 25°C) on the biomass of the Douglas-fir (Pseudotsuga menziesii) and Norway spruce (Picea abies) seedlings were studied. Mycorrhization compensated the adverse effects of PAC on the growth of the Norway spruce at both temperatures. The growth of the Douglas-fir was not influenced either by PAC or mycorrhization at 19°C, but at 25°C mycorrhization had a similar protective effect as in the Norway spruce. The compensatory effects probably rely on the reduction of the PAC-colonization density by mycorrhizae. Temperature and the PAC strain only had a differential effect on the biomass of the Norway spruce but not on the Douglas-fir. Higher temperature reduced mycorrhization of both hosts. We conclude that ectomycorrhizae form physical and/or physiological barriers against PAC leading to reduced PAC-colonization of the roots. Additionally, our results indicate that global warming could cause a general decrease of mycorrhization making primary roots more accessible to other symbionts and pathogens.

  17. Pre- and Post-Fire Infiltration Rates in a Montane Mixed Conifer Ecosystem

    NASA Astrophysics Data System (ADS)

    Kopp, E. S.; Pohlmann, M. A.; Jones, C. A.; Chorover, J.; Schaap, M. G.

    2013-12-01

    The NSF-funded Catalina-Jemez Critical Zone Observatory (CZO) studies couplings among hydrologic, lithologic, ecological, and geochemical dynamics in the Southwest U.S. The motivation to study this region is to understand and to develop predictive models of how slow changes and abrupt disturbances affect landscape evolution and water resources for growing urban populations. One of the prevalent disturbances in Southwestern forested ecosystems is fire, which can dramatically alter near surface hydraulic properties and cause large changes in hydrological response in catchments. This poster will present a unique data set of pre- and post-fire infiltration and subsurface data collected before and shortly after the June 2013 Thompson Ridge Fire near Redondo Peak in the Valles Caldera 10 miles north of Jemez Springs, NM. Single ring pre-fire infiltration measurements were taken in July 2011 at 22 different locations with high-precision GPS tags. Similar post-fire infiltration measurements were taken within 1 meter of spatial accuracy of the pre-fire measurements in July 2013. The near-surface soil was analyzed for texture and organic matter content at 53 GPS-referenced locations in 2011, and a more detailed soil analysis is currently being analyzed in the laboratory for the 22 infiltration sites (5 depth increments down to about 50 cm). Because of the recent nature of the burn and subsequent sampling, complete results from data analysis are not yet available, however, the poster will provide a statistical analysis among pre- and post fire infiltration rates, established burn intensity classes, and subsurface changes such as soil texture and organic matter content.

  18. Biogeochemical prospecting for uranium with conifers: results from the Midnite Mine area, Washington

    USGS Publications Warehouse

    Nash, J. Thomas; Ward, Frederick Norville

    1977-01-01

    The ash of needles, cones, and duff from Ponderosa pine (Pinus ponderosa Laws) growing near uranium deposits of the Midnite mine, Stevens County, Wash., contain as much as 200 parts per million (ppm) uranium. Needle samples containing more than 10 ppm uranium define zones that correlate well with known uranium deposits or dumps. Dispersion is as much as 300 m but generally is less. Background is about 1 ppm. Tree roots are judged to be sampling ore, low-grade uranium halo, or ground water to a depth of about 15 m. Uptake of uranium by Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) needles appears to be about the same as by Ponderosa pine needles. Cones and duff are generally enriched in uranium relate to needles. Needles, cones, and duff are recommended as easily collected, uncomplicated sample media for geochemical surveys. Samples can be analyzed by standard methods and total cost per sample kept to about $6.

  19. MODIFYING LIGNIN IN CONIFERS: THE ROLE OF HCT DURING TRACHEARY ELEMENT FORMATION IN PINUS RADIATA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The enzyme hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyltransferase (HCT) is involved in the production of methoxylated monolignols that are precursors to guaiacyl and syringyl lignin in angiosperm species. We identified and cloned a putative HCT gene from Pinus radiata, a coniferous gymnosperm, ...

  20. A novel Fusarium species causes a canker disease of the critically endangered conifer, Torreya taxifolia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A canker disease of Florida torreya (Torreya taxifolia), here designated CDFT, has been implicated in the decline of this critically endangered species in its native range of northern Florida and southeastern Georgia. In our current surveys of eight Florida torreya sites, cankers were present on all...

  1. Effect of tree structure on X-band microwave signature of conifers

    NASA Technical Reports Server (NTRS)

    Mougin, Eric; Lopes, Armand; Karam, Mostafa A.; Fung, Adrian K.

    1993-01-01

    Experimental studies are performed on some coniferous trees (Austrian pine, Nordmann spruce, and Norway spruce) to investigate the relation between the tree architecture and radar signal at X-band. For a single tree, the RCS is measured as a function of the scatterer location at 90 deg incidence. It is found that the main scatterers are the leafy branches and the difference between sigma(vv) and sigma(hh) is significant at the upper portion of the tree. At the lower portion of the tree, sigma(vv) and sigma(hh) have almost the same level. For a group of trees the angular trends of sigma(vv) and sigma(hh) are measured. It is found that the levels of sigma(vv) and sigma(hh) are of the same order, but their angular trends vary from one tree species to the other depending on the tree species structure. The interpretation of these experimental results is carried out with the help of a theoretical model which accounts for the structure of the tree. According to this theoretical study, the major scattering trend is due to the leaves, while the perturbation to the angular trend and the level difference between sigma(vv) and sigma(hh) are due to the branch orientation distributions (i.e., the tree architecture).

  2. Warming delays autumn declines in photosynthetic capacity in a boreal conifer, Norway spruce (Picea abies).

    PubMed

    Stinziano, Joseph R; Hüner, Norman P A; Way, Danielle A

    2015-12-01

    Climate change, via warmer springs and autumns, may lengthen the carbon uptake period of boreal tree species, increasing the potential for carbon sequestration in boreal forests, which could help slow climate change. However, if other seasonal cues such as photoperiod dictate when photosynthetic capacity declines, warmer autumn temperatures may have little effect on when carbon uptake capacity decreases in these species. We investigated whether autumn warming would delay photosynthetic decline in Norway spruce (Picea abies (L.) H. Karst.) by growing seedlings under declining weekly photoperiods and weekly temperatures either at ambient temperature or a warming treatment 4 °C above ambient. Photosynthetic capacity was relatively constant in both treatments when weekly temperatures were >8 °C, but declined rapidly at lower temperatures, leading to a delay in the autumn decline in photosynthetic capacity in the warming treatment. The decline in photosynthetic capacity was not related to changes in leaf nitrogen or chlorophyll concentrations, but was correlated with a decrease in the apparent fraction of leaf nitrogen invested in Rubisco, implicating a shift in nitrogen allocation away from the Calvin cycle at low autumn growing temperatures. Our data suggest that as the climate warms, the period of net carbon uptake will be extended in the autumn for boreal forests dominated by Norway spruce, which could increase total carbon uptake in these forests.

  3. Physiological limitation at alpine treeline: relationships of threshold responses of conifers to their establishment patterns

    NASA Astrophysics Data System (ADS)

    Germino, M. J.; Lazarus, B.; Castanha, C.; Moyes, A. B.; Kueppers, L. M.

    2014-12-01

    An understanding of physiological limitations to tree establishment at alpine treeline form the basis for predicting how this climate-driven boundary will respond to climate shifts. Most research on this topic has focused on limitations related to carbon balance and growth of trees. Carbon balance could limit survival and establishment primarily through slow-acting, chronic means. We asked whether tree survival and thus establishment patterns reflect control by chronic effects in comparison to acute, threshold responses, such as survival of frost events. Seedling survivorship patterns were compared to thresholds in freezing (temperature causing leaf freezing, or freezing point, FP; and physiological response to freezing) and water status (turgor loss point, TLP; and related physiological adjustments). Subject seedlings were from forest, treeline, and alpine sites in the Alpine Treeline Warming Experiment in Colorado, and included limber and lodgepole pine (a low-elevation species), and Engelmann Spruce. Preliminary results show survival increases with seedling age, but the only corresponding increase in stress acclimation was photosynthetic resistance to freezing and TLP, not FP. Differences in survivorship among the species were not consistent with variation in FP but they generally agreed with variation in photosynthetic resistance to deep freezing and to early-season drought avoidance. Mortality of limber pine increased 35% when minimum temperatures decreased below -9C, which compares with FPs of >-8.6C, and about 1/3 of its mortality occurred during cold/wet events, particularly in the alpine. The other major correlate of mortality is midsummer drying events, as previously reported. Also in limber pine, the TLP for year-old seedlings (-2.5 MPa) corresponded with seasonal-drought mortality. In summary, we show several examples of correspondence in physiological thresholds to mortality events within a species, although the relationships are not strong. Across species, photosynthetic resistance to freezing and early-season drought avoidance related well to mortality patterns. These results are generally more supportive of the role of chronic rather than acute climate effects in broad patterns of tree seedling establishment at treeline.

  4. Evolutionary history of the conifer root rot fungus Heterobasidion annosum sensu lato.

    PubMed

    Dalman, K; Olson, A; Stenlid, J

    2010-11-01

    We investigated two hypotheses for the origin of the root rot fungus Heterobasidion annosum species complex: (i) that geology has been an important factor for the speciation (ii) that co-evolutionary processes with the hosts drove the divergence of the pathogen species. The H. annosum species complex consists of five species: three occur in Europe, H. annosum s.s., Heterobasidion parviporum and Heterobasidion abietinum, and two in North America, Heterobasidion irregulare and Heterobasidion occidentale; all with different but partially overlapping host preferences. The evolution of the H. annosum species complex was studied using six partially sequenced genes, between 10 and 30 individuals of each species were analysed. Neighbour-joining trees were constructed for each gene, and a Bayesian tree was built for the combined data set. In addition, haplotype networks were constructed to illustrate the species relationships. For three of the genes, H. parviporum and H. abietinum share haplotypes supporting recent divergence and/or possible gene flow. We propose that the H. annosum species complex originated in Laurasia and that the H. annosum s.s./H. irregulare and H. parviporum/H. abietinum/H. occidentale ancestral species emerged between 45 and 60 Ma in the Palaearctic, well after the radiation of the host genera. Our data imply that H. irregulare and H. occidentale were colonizing North America via different routes. In conclusion, plate tectonics are likely to have been the main factor influencing Heterobasidion speciation and biogeography. PMID:20964759

  5. Hydraulic and carbohydrate changes in experimental drought-induced mortality of saplings in two conifer species.

    PubMed

    Anderegg, William R L; Anderegg, Leander D L

    2013-03-01

    Global patterns of drought-induced forest die-off indicate that many forests may be sensitive to climate-driven mortality, but the lack of understanding of how trees and saplings die during drought hinders the projections of die-off, demographic bottlenecks and ecosystem trajectories. In this study, we performed a severe controlled drought experiment on saplings of Pinus edulis Engelm. and Juniperus osteosperma (Torr.) Little, two species that both experienced die-off in a recent 'climate change-type' drought. We examined the roles of carbohydrate and hydraulic changes in multiple tissues as the saplings died. We found that saplings of both species exhibited large degrees of loss of hydraulic conductivity prior to death. Neither species exhibited significant changes in carbohydrate concentrations in any tissue during the relatively short and severe imposed drought. Native hydraulic conductivity successfully predicted the degree of canopy mortality in both species, highlighting the importance of drought characteristics and tree attributes in influencing physiological pathways to mortality. The relationships elucidated here, as well as the differences between our results and previous findings in adult trees, can help inform mortality mechanisms in climate-vegetation models, especially for young trees, and to understand species response to severe drought across ontogeny. PMID:23514762

  6. [Characteristics of morphogenesis and growth processes of conifers in the Chernobyl nuclear accident zone].

    PubMed

    Kozubov, G M; Taskaev, A I

    2007-01-01

    In the article we present data on the study of morphogenesis and of growth processes of Scotch pine (Pinus sylvestris L.) and of Norwey spruce (Picea abies (L.) Karst.) vegetative organs after radiation exposure in the Chernobyl nuclear accident zone. The anomalies in morphogenesis processes at different absorbed doses are described in detail. It is established that the death of pine forest began under absorbed dose 80-100 Gy and more, mass yellowing of needles at 50-60 Gy, and maximal morphosis at 8-12 Gy. Inhibition phenomenon of growth processes under acute irradiation and giantism under durable chronic irradiation were also put under investigation. Features of radiation exposure on pine and fir growth processes at different ontogeny phases were characterized. High radio-sensitivity of Norwey spruce is established.

  7. Maximum height in a conifer is associated with conflicting requirements for xylem design

    SciTech Connect

    Domec, Jean-Christophe; Lachenbruch, Barbara; McCulloh, Katherine A.; Meinzer, Rick; Woodruff, David R.; Warren, Jeffrey M.

    2008-08-01

    Despite renewed interest in the nature of limitations on maximum tree height, the mechanisms governing ultimate and species-specific height limits are not yet understood, but they likely involve water transport dynamics. Tall trees experience increased risk of xylem embolism from air-seeding because tension in their water column increases with height because of path-length resistance and gravity. We used morphological measurements to estimate the hydraulic properties of the bordered pits between tracheids in Douglas-fir trees along a height gradient of 85 m. With increasing height, the xylem structural modifications that satisfied hydraulic requirements for avoidance of runaway embolism imposed increasing constraints on water transport efficiency. In the branches and trunks, the pit aperture diameter of tracheids decreases steadily with height, whereas torus diameter remains relatively constant. The resulting increase in the ratio of torus to pit aperture diameter allows the pits to withstand higher tensions before air-seeding but at the cost of reduced pit aperture conductance. Extrapolations of vertical trends for trunks and branches show that water transport across pits will approach zero at a heights of 109 m and 138 m, respectively, which is consistent with historic height records of 100 127 m for this species. Likewise, the twig water potential corresponding to the threshold for runaway embolism would be attained at a height of 107 m. Our results suggest that the maximum height of Douglas-fir trees may be limited in part by the conflicting requirements for water transport and water column safety

  8. The effect of soil water deficit on the reflectance of conifer seedling canopies

    NASA Technical Reports Server (NTRS)

    Fox, L.

    1977-01-01

    The effects of soil water deficit on spruce and pine seedling canopy reflectance, needle reflectance and transmittance, and canopy density were measured in a greenhouse with a diffuse source of radiant flux. A potential for early or pre-visual detection of plant water stress was not supported by these measurements made at visible, and reflected infrared wavelengths to 1950 nm. Needles were found to transmit approximately thirty percent of the radiant flux incident on them at 780 nm, ten percent at 700 nm, and were found to be opaque at 450, 550, 600 and 650 nm.

  9. Environmental effects on stem water deficit in co-occurring conifers exposed to soil dryness

    NASA Astrophysics Data System (ADS)

    Oberhuber, Walter; Kofler, Werner; Schuster, Roman; Wieser, Gerhard

    2015-04-01

    We monitored dynamics of stem water deficit (Δ W) and needle water potential ( Ψ) during two consecutive growing seasons (2011 and 2012) in a dry inner Alpine environment (750 m above sea level, Tyrol, Austria), where Pinus sylvestris, Picea abies and Larix decidua form mixed stands. Δ W was extracted from stem circumference variations, which were continuously recorded by electronic band dendrometers (six trees per species) and correlations with environmental variables were performed. Results revealed that (i) Δ W reached highest and lowest values in P. abies and L. decidua, respectively, while mean minimum water potential ( Ψ ea) amounted to -3.0 MPa in L. decidua and -1.8 MPa in P. abies and P. sylvestris. (ii) Δ W and Ψ ea were significantly correlated in P. abies ( r = 0.630; P = 0.038) and L. decidua ( r = 0.646; P = 0.032). (iii) In all species, Δ W reached highest values in late summer and was most closely related to temperature ( P < 0.001). Results indicate that all species were undergoing water limitations as measured by increasing Δ W throughout the growing season, whereby P. abies most strongly drew upon water reserves in the living tissues of the bark. Quite similar Δ W developed in drought-sensitive L. decidua and drought-tolerant P. sylvestris indicate that various water storage locations are depleted in species showing different strategies of water status regulation, i.e. anisohydric vs. isohydric behavior, respectively, and/or water uptake efficiency differs among these species. Close coupling of Δ W to temperature suggests that climate warming affects plant water status through its effect on atmospheric demand for moisture.

  10. Seed and vegetative production of shrubs and growth of understory conifer regeneration

    USGS Publications Warehouse

    Wender, B.; Harrington, C.; Tappeiner, J.C.

    2004-01-01

    We observed flower and fruit production for nine understory shrub species in western Washington and Oregon and examined the relationships between shrub reproductive output and plant size, plant age, site factors, and overstory density to determine the factors that control flowering or fruiting in understory shrubs. In Washington, 50 or more shrubs or microplots (for rhizomatous species) were sampled for each of eight species. The variables examined were more useful for explaining abundance of flowers or fruit on shrubs than they were for explaining the probability that a shrub would produce flowers or fruit. Plant size was consistently the most useful predictor of flower/fruit abundance in all species; plant age was also a good predictor of abundance and was strongly correlated with plant size. Site variables (e.g., slope) and overstory competition variables (e.g., presence/absence of a canopy gap) also helped explain flower/fruit abundance for some species. At two Oregon sites, the responses of five species to four levels of thinning were observed for 2-4 yr (15 shrubs or microplots per treatment per year). Thinning increased the probability and abundance of flowering/fruiting for two species, had no effect on one species, and responses for two other species were positive but inconsistent between sites or from year to year. We believe reducing overstory density or creating canopy gaps may be useful tools for enhancing shrub size and vigor, thus, increasing the probability and abundance of fruiting in some understory shrub species.

  11. Fire and Climate History of Mixed Conifer Woodlands in the Great Basin, USA

    NASA Astrophysics Data System (ADS)

    Biondi, F.; Bradley, M.; Cheek, J.; Jamieson, L.; Kilpatrick, M.; Sibold, J.; Strachan, S. D.

    2010-12-01

    We investigated climate, fire, and species dynamics before and after Euro-American settlement at two locations in Lincoln County, Nevada. Both the Mt. Irish and Clover Mountains sites are isolated high ranges in the southern Great Basin Desert, not far from the floristic boundary with the northern Mojave Desert. At Mt. Irish, non-scarred ponderosa pines and single-leaf piñons were used to develop a tree-ring reconstruction of drought (mean PDSI for May-July, NV Clim. Div. 3) from 1396 to 2003. Fire-scarred ponderosas found at both study areas were then sampled, and crossdated fire-scar records were used to generate the fire history. A total of 12 plots, each 0.1 ha in size, was sampled at each site to quantify stand structure, age of surviving trees, and fuel loads. Additional information on species dynamics were collected at regularly spaced grid points. Density of pinyon pine at both sites has more than doubled since Euro-American settlement, with peak survivorship occurring in 1900-1940 at Mount Irish and 1930-1970 at the Clover Mountains. Pre-settlement trees occur throughout each site, particularly at Mount Irish, where in 1550-1860 fires that scarred at least two trees were very frequent (mean fire return interval: 4 years), while fires that scarred at least 10% of the recorder trees were relatively rare (mean fire return interval: 66 years). At the Clover Mountains, for the period 1785-2007, fires that scarred at least two trees and fires that scarred at least 10% of the recorder trees had more similar mean fire return intervals: 7 and 12 years. Fire frequency did not decrease during the 1780-1840 period, when fire was reduced or absent in other areas of the western United States. Much lower fire frequency was noted after Euro-American settlement at Mt. Irish, most likely because of less favorable climatic conditions, while the difference was less pronounced, and also affected by fire suppression activity, at the Clover Mountains. Fuel loads at the two sites were different, with those at the Clover Mountains favoring a higher rate of surface fire spread compared to Mount Irish, which however is currently at a greater risk for a high-intensity crown fire. In addition, based on fuel reconstructions, a potential change in fire behavior from a surface to a crown fire occurred after settlement at the Clover Mountains and prior to settlement at Mount Irish.

  12. Seasonal dynamics of mobile carbohydrate pools in phloem and xylem of two alpine timberline conifers

    PubMed Central

    GRUBER, A.; PIRKEBNER, D.; OBERHUBER, W.

    2016-01-01

    Recent studies on non-structural carbohydrate (NSC) reserves in trees focused on xylem NSC reserves, while still little is known about changes in phloem carbohydrate pools, where NSC charging might be significantly different. To gain insight on NSC dynamics in xylem and phloem, we monitored NSC concentrations in stems and roots of Pinus cembra and Larix decidua growing at the alpine timberline throughout 2011. Species-specific differences affected tree phenology and carbon allocation in the course of the year. After a delayed start in spring, NSC concentrations in Larix decidua were significantly higher in all sampled tissues from August until end of growing season. In both species NSC concentrations were five to seven times higher in phloem than in xylem. However, significant correlations between xylem and phloem starch content found for both species indicate a close linkage between long term carbon reserves in both tissues. In Larix decidua also free sugar concentrations in xylem and phloem were significantly correlated throughout the year, while missing correlations between xylem and phloem free sugar pools in Pinus cembra indicate a decline of phloem soluble carbohydrate pools during periods of high sink demand. PMID:24186941

  13. EFFECTS OF ELEVATED CO2 AND OTHER ENVIRONMENTAL STRESSES ON WESTERN CONIFER SEEDLINGS

    EPA Science Inventory

    The future productivity of forests will be affected by increased levels of atmospheric CO2 which will likely be associated with climate change and regional air pollutants such as O3. We have conducted two long-term experiments to determine the effects of elevated CO2 and other s...

  14. Evidence for Air-Seeding: Watching the Formation of Embolism in Conifer Xylem

    PubMed Central

    Mayr, S.; Kartusch, B.; Kikuta, S.

    2016-01-01

    Water transport in plants is based on a metastable system as the xylem “works” at negative water potentials (ψ). At critically low ψ, water columns can break and cause embolism. According to the air-seeding hypothesis, this occurs by air entry via the pits. We studied the formation of embolism in dehydrating xylem sections of Juniperus virginiana (Cupressaceae), which were monitored microscopically and via ultrasonic emission analyses. After replacement of water by air in outer tracheid layers, a complex movement of air-water menisci into tracheids was found. With decreasing ψ, pits started to aspirate and the speed of menisci movements increased. In one experiment, an airseeding event could be detected at a pit. The onset of ultrasonic activity was observed when pits started to close, and ultrasonic emission ceased at intense dehydration. Experiments clearly indicated that predictions of the air-seeding hypothesis are correct: At low ψ, pit mechanisms to prevent air entry failed and air spread into tracheids. ψ fluctuations caused complex movements of air-water menisci and pits, and at low ψ, air-seeding caused ultrasonic emissions. Main insights are presented in a video.

  15. Incipient silicification of recent conifer wood at a Yellowstone hot spring

    NASA Astrophysics Data System (ADS)

    Hellawell, Jo; Ballhaus, Chris; Gee, Carole T.; Mustoe, George E.; Nagel, Thorsten J.; Wirth, Richard; Rethemeyer, Janet; Tomaschek, Frank; Geisler, Thorsten; Greef, Karin; Mansfeldt, Tim

    2015-01-01

    A branch of lodgepole pine (Pinus contorta) from a silica sinter apron of Cistern Spring, Yellowstone National Park, is partially mineralized with silica gel. The distribution of Si mapped in transverse sections of the branch suggests that mineralization was episodic. Early silica-rich solutions used the cellular structures in the wood as pathways, in particular the axial tracheids and rays. Later solutions infiltrated into the branch through shrinkage cracks along the decorticated branch's periphery. Among the tracheids, a distinct preference is noted for silica precipitates to line lumina of the earlywood tracheids, suggesting that this differential concentration in silica may reflect seasonal growth and water uptake in a live tree. Raman spectroscopy identifies the silica phases as amorphous silica gel. Secondary electron images of radial sections along the tracheids demonstrate that the distribution of silica is heterogeneous on a micrometer scale. Silica gel precipitates form micro spheroids with a spherical substructure that extends down to the sub-nanometer scale. All cell walls are templated with a monolayer consisting of closely spaced silica gel nano spheres around 100 nm in diameter. Transmission electron microscopy of focused ion beam sections through cell walls of partially mineralized tracheids reveals that the permineralization of cellular structures and the replacement of organic material by silica are processes that go hand in hand. The branch is dated with the 14C chronometer to 140 ± 33 years, underlining that the silicification reactions that preserve wood in the fossil record can be very rapid. Textural considerations of Si distribution in the wood suggest that the early stages of silicification in this branch date from a time when the pine tree was still alive.

  16. Acid mist and ozone effects on the leaf chemistry of two western conifer species.

    PubMed

    Westman, W E; Temple, P J

    1989-01-01

    Seedlings of Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were more susceptible to leaf chemical changes following exposure to acid mist (pH 3.4-2.0) or acid mist/ozone combinations, than to ozone alone (0.1-0.2 microl/litre), when plants were exposed to alternating doses of these pollutants for 6-9 weeks. Under acid mist treatment, leaves exhibited higher levels of nitrogen and sulfur, two elements applied in acid mist. In addition, levels of foliar sodium, and, in the case of giant sequia, potassium, as well, increased under acid mist treatment. Iron and manganese were also mobilized, resulting in significant increases in these elements in pine, and decreases in manganese in giant sequoia foliage. The acid treatment also reduced chlorophyll b concentrations in pine, and, to a less significant extent, in giant sequoia. Calcium, magnesium, barium and strontium were differentially accumulated in giant sequoia compared to Jeffrey pine. Under acid mist treatment, all of these elements (except strontium) declined in concentration in giant sequoia, with calcium showing the most significant trend. The more extensive changes in leaf chemistry induced by acid mist are consistent with earlier observations of significant changes in spectral reflectance of these seedlings after 3 weeks of fumigation. Limited foliage samples collected from these two species in 1985 and 1986 in Sequoia/Kings Canyon National Parks in the southern Sierra Nevada do not in themselves indicate any clearcut or severe effects of ozone alone on leaf chemistry of these species, but a mild influence of nitrate-laden acid deposition, possibly in combination with ozone, is consistent with the rise in nitrogen and lignin levels in Jeffrey pine on sites observed to have moderate visible injury symptoms. No firm conclusions about effects of pollutants on leaf chemistry in these field sites is possible without further study. PMID:15092463

  17. LANDSCAPE PATTERNS OF NET NITRIFICATION IN A NORTHERN HARDWOOD-CONIFER FOREST. (R827674)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  18. Alteration of belowground carbon dynamics by nitrogen addition in southern California mixed conifer forests

    SciTech Connect

    Nowinski, Nicole S.; Trumbore, Susan E.; Jimenez, Gloria; Fenn, Mark E.

    2009-04-01

    Nitrogen deposition rates in southern California are the highest in North America and have had substantial effects on ecosystem functioning. We document changes in the belowground C cycle near ponderosa pine trees experiencing experimental nitrogen (N) addition (50 and 150 kg N ha 1 a 1 as slow release urea since 1997) at two end member sites along a pollution gradient in the San Bernardino Mountains, California. Despite considerable differences in N deposition between the two sites, we observed parallel changes in microbial substrate use and soil enzyme activity with N addition. 14C measurements indicate that the mean age of C respired by the Oa horizon declined 10 15 years with N addition at both sites. N addition caused an increase in cellulolytic enzyme activity at the polluted site and a decrease in ligninolytic enzyme activity at the unpolluted site. Given the likely differences in lignin and cellulose ages, this could explain the difference in the age of microbial respiration with N addition. Measurements of fractionated soil organic matter did not show the same magnitude of changes in response to N addition as were observed for respired C. This lesser response was likely because the soils are mostly composed of C having turnover times of decades to centuries, and 9 years of N amendment were not enough to affect this material. Consequently, 14C of respired CO2 provided a more sensitive indicator of the effects of N addition than other methods. Results suggest that enhanced N deposition alone may not result in increased soil C storage in xeric ecosystems.

  19. Examining the Physical Drivers of Photosynthetic Temperature Sensitivity Within a Sub-alpine Mixed Conifer Forest

    NASA Astrophysics Data System (ADS)

    Yang, J.; Barron-Gafford, G.; Minor, R.; Heard, M.

    2013-12-01

    Current projections of climate change in the southwestern U.S. suggest increasing temperatures and reduced summer precipitation. High temperature and water deficits have major influence on ecosystem functioning by restricting plant growth and productivity. However, there are limited data on what influences plant sensitivity to temperature, and these dynamics are not often captured in ecosystem models. Understanding the sensitivities, linkages, and feedbacks among biotic processes and abiotic forces is especially important within Critical Zone Sciences, which seeks to integrate among disciplines. Here, we analyzed several potential drivers of photosynthetic temperature sensitivity, including differences in soil parent material, aspect, and seasonality within a suite of species. Each of these variables captures a different physical driver: (i) soil parent material influences water holding capacity of the soil; (ii) aspect influences how incoming energy drives evaporative loss of soil water, creating warmer and drier environments on south/east faces; and (iii) seasonality captures temporal patterns of soil moisture recharge. Our research was conducted within two V shaped zero-order catchment basins of the Santa Catalina Critical Zone Observatory in southern Arizona, one with schist bedrock and the other with granite. We used leaf-level gas exchange measurements on 24 trees across a range of temperatures to quantify this plant temperature sensitivity during the dry pre-monsoon and wet monsoon seasons. Preliminary results show that maximum photosynthetic rate was 51% higher during the monsoon than pre-monsoon season. Optimal photosynthetic temperature decreased 25% while the span of functional temperatures (Ω50) was 21% higher following the onset of monsoon rains. During the rainy season, soil parent material became an important factor. The greater water holding capacity of schist soils yielded greater maximum photosynthesis and reduced tree sensitivity to higher temperatures. This variability in the temperature sensitivity and the responsiveness of that sensitivity to increases in available soil moisture is important as we consider the structure and composition of our future forests. More detailed analysis will allow us to examine the relative influence of each abiotic variable in driving this photosynthetic response, which impacts a suite of downstream critical zone processes.

  20. LANDSCAPE PATTERNS OF SOIL NITRATE PRODUCTION IN A NORTHERN HARDWOOD-CONIFER FOREST. (R827674)

    EPA Science Inventory

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