Science.gov

Sample records for passionfruit woodiness disease

  1. Characterization and distribution of a Potyvirus associated with passion fruit woodiness disease in Uganda

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper describes the incidence and etiology of viral infection on passion fruit in Uganda. Viral disease symptoms, including those characteristic of Passion fruit woodiness disease (PWD), were observed in producing areas with an overall mean infection level of 27%. Electron microscopic observati...

  2. Genome Sequence of Euphorbia mosaic virus from Passionfruit and Euphorbia heterophylla in Florida

    PubMed Central

    Londoño, M. A.; Cohen, A. L.; Padilla-Rodriguez, M.; Rosario, K.; Breitbart, M.

    2017-01-01

    ABSTRACT Euphorbia mosaic virus (EuMV) was found in a symptomatic passionfruit (Passiflora edulis) plant from Homestead, Florida, USA, as well as in the symptomatic weed Euphorbia heterophylla. This is the first identification of EuMV in Florida and the United States and the first report of a natural infection of passionfruit by EuMV. PMID:28254981

  3. Genome Sequence of Euphorbia mosaic virus from Passionfruit and Euphorbia heterophylla in Florida.

    PubMed

    Polston, J E; Londoño, M A; Cohen, A L; Padilla-Rodriguez, M; Rosario, K; Breitbart, M

    2017-03-02

    Euphorbia mosaic virus (EuMV) was found in a symptomatic passionfruit (Passiflora edulis) plant from Homestead, Florida, USA, as well as in the symptomatic weed Euphorbia heterophylla This is the first identification of EuMV in Florida and the United States and the first report of a natural infection of passionfruit by EuMV.

  4. The Microflora of Frozen Passionfruit Nectar Base1

    PubMed Central

    Aea, Raymond T. F.; Bushnell, O. A.

    1962-01-01

    A considerable and varied microflora is introduced into passionfruit nectar base under present methods of production. In spite of the great acidity of the nectar base (pH range: 2.8 to 3.2), the high sucrose concentration (approximately 50%), and storage at -20 C, remnants of the microflora persist for a year or longer. During storage, however, there is a steady and gradual decrease, until after about 18 months the microflora is near to extinction. Sample regression lines show straight-line slopes for this diminution in numbers. A battery of nine media was used to grow a representative aerobic flora. Purified cultures of isolates were identified to genera. Yeasts were the most numerous organisms in all samples, followed by molds, bacteria, and streptomycetes. The bacteria were the first group to disappear during storage. No fecal streptococci or gram-negative bacilli were found in any samples. PMID:13859495

  5. Low Dose Gamma Irradiation Does Not Affect the Quality or Total Ascorbic Acid Concentration of "Sweetheart" Passionfruit (Passiflora edulis).

    PubMed

    Golding, John B; Blades, Barbara L; Satyan, Shashirekha; Spohr, Lorraine J; Harris, Anne; Jessup, Andrew J; Archer, John R; Davies, Justin B; Banos, Connie

    2015-08-26

    Passionfruit (Passiflora edulis, Sims, cultivar "Sweetheart") were subject to gamma irradiation at levels suitable for phytosanitary purposes (0, 150, 400 and 1000 Gy) then stored at 8 °C and assessed for fruit quality and total ascorbic acid concentration after one and fourteen days. Irradiation at any dose (≤1000 Gy) did not affect passionfruit quality (overall fruit quality, colour, firmness, fruit shrivel, stem condition, weight loss, total soluble solids level (TSS), titratable acidity (TA) level, TSS/TA ratio, juice pH and rot development), nor the total ascorbic acid concentration. The length of time in storage affected some fruit quality parameters and total ascorbic acid concentration, with longer storage periods resulting in lower quality fruit and lower total ascorbic acid concentration, irrespective of irradiation. There was no interaction between irradiation treatment and storage time, indicating that irradiation did not influence the effect of storage on passionfruit quality. The results showed that the application of 150, 400 and 1000 Gy gamma irradiation to "Sweetheart" purple passionfruit did not produce any deleterious effects on fruit quality or total ascorbic acid concentration during cold storage, thus supporting the use of low dose irradiation as a phytosanitary treatment against quarantine pests in purple passionfruit.

  6. Survival Times of Selected Enteropathogenic Bacteria in Frozen Passionfruit Nectar Base

    PubMed Central

    Aea, Raymond T. F.; Bushnell, O. A.

    1962-01-01

    Five test organisms were used: Escherichia coli, Salmonella typhosa, Salmonella schottmuelleri, Salmonella enteritidis, and Shigella paradysenteriae. Even when large inocula of these test cultures were introduced into fresh passionfruit nectar base, all test organisms were killed within 1 to 2 hr, provided the nectar base was held at room temperature for more than 1 hr before freezing. If the nectar base was frozen immediately after inoculation, four of the five test organisms were eliminated almost as quickly. But the fifth, Salmonella enteritidis, proved to be exceptional: it was being recovered after 90 days of storage at -20 C, when the last available sample was analyzed. PMID:13859494

  7. Low Dose Gamma Irradiation Does Not Affect the Quality or Total Ascorbic Acid Concentration of “Sweetheart” Passionfruit (Passiflora edulis)

    PubMed Central

    Golding, John B.; Blades, Barbara L.; Satyan, Shashirekha; Spohr, Lorraine J.; Harris, Anne; Jessup, Andrew J.; Archer, John R.; Davies, Justin B.; Banos, Connie

    2015-01-01

    Passionfruit (Passiflora edulis, Sims, cultivar “Sweetheart”) were subject to gamma irradiation at levels suitable for phytosanitary purposes (0, 150, 400 and 1000 Gy) then stored at 8 °C and assessed for fruit quality and total ascorbic acid concentration after one and fourteen days. Irradiation at any dose (≤1000 Gy) did not affect passionfruit quality (overall fruit quality, colour, firmness, fruit shrivel, stem condition, weight loss, total soluble solids level (TSS), titratable acidity (TA) level, TSS/TA ratio, juice pH and rot development), nor the total ascorbic acid concentration. The length of time in storage affected some fruit quality parameters and total ascorbic acid concentration, with longer storage periods resulting in lower quality fruit and lower total ascorbic acid concentration, irrespective of irradiation. There was no interaction between irradiation treatment and storage time, indicating that irradiation did not influence the effect of storage on passionfruit quality. The results showed that the application of 150, 400 and 1000 Gy gamma irradiation to “Sweetheart” purple passionfruit did not produce any deleterious effects on fruit quality or total ascorbic acid concentration during cold storage, thus supporting the use of low dose irradiation as a phytosanitary treatment against quarantine pests in purple passionfruit. PMID:28231212

  8. Radium concentration factors in passionfruit (Passiflora foetida) from the Alligator Rivers Region, Northern Territory, Australia.

    PubMed

    Medley, Peter; Bollhöfer, Andreas; Parry, David; Martin, Paul

    2013-12-01

    In this study, uptake of Ra from soil into the edible fruit of the wild passionfruit species Passiflora foetida was investigated, using selective extraction from the soil samples. A wide range of environmental exposure conditions were represented by the locations that were sampled, including both natural soils, and soils influenced by past and present uranium mining activities. The bioavailable (226)Ra fraction in soils was found to be a better predictor of (226)Ra fruit activity concentrations than the total soil activity concentration, or any of the other fractions studied. Concentration Factors (CFs) derived using the bioavailable fraction varied by only a factor of 7 between different locations, whereas CFs derived using other fractions and total soil varied by up to two orders of magnitude. CFs were highest for those soils containing the lowest concentrations of Mg, Ca and Ba, and approached a saturation value at higher soil concentrations. This finding suggests that group II elements influence radium uptake, most likely the result of increased pressure on the plant to take up essential nutrient group II elements from soil with the lower concentrations, with Ra being taken up as an analogue element. It is also possible that at higher concentrations of bioavailable Ca and Mg in the soil, these ions will outcompete Ra for adsorption sites in the soil and/or on the root surfaces. The study also shows that (228)Ra can potentially be a significant contributor to ingestion doses and should also be considered when assessing committed effective doses from the ingestion of fruits.

  9. Can vessel dimension explain tolerance toward fungal vascular wilt diseases in woody plants? Lessons from Dutch elm disease and esca disease in grapevine

    PubMed Central

    Pouzoulet, Jérôme; Pivovaroff, Alexandria L.; Santiago, Louis S.; Rolshausen, Philippe E.

    2014-01-01

    This review illuminates key findings in our understanding of grapevine xylem resistance to fungal vascular wilt diseases. Grapevine (Vitis spp.) vascular diseases such as esca, botryosphaeria dieback, and eutypa dieback, are caused by a set of taxonomically unrelated ascomycete fungi. Fungal colonization of the vascular system leads to a decline of the plant host because of a loss of the xylem function and subsequent decrease in hydraulic conductivity. Fungal vascular pathogens use different colonization strategies to invade and kill their host. Vitis vinifera cultivars display different levels of tolerance toward vascular diseases caused by fungi, but the plant defense mechanisms underlying those observations have not been completely elucidated. In this review, we establish a parallel between two vascular diseases, grapevine esca disease and Dutch elm disease, and argue that the former should be viewed as a vascular wilt disease. Plant genotypes exhibit differences in xylem morphology and resistance to fungal pathogens causing vascular wilt diseases. We provide evidence that the susceptibility of three commercial V. vinifera cultivars to esca disease is correlated to large vessel diameter. Additionally, we explore how xylem morphological traits related to water transport are influenced by abiotic factors, and how these might impact host tolerance of vascular wilt fungi. Finally, we explore the utility of this concept for predicting which V. vinifera cultivars are most vulnerable of fungal vascular wilt diseases and propose new strategies for disease management. PMID:24971084

  10. Can vessel dimension explain tolerance toward fungal vascular wilt diseases in woody plants? Lessons from Dutch elm disease and esca disease in grapevine.

    PubMed

    Pouzoulet, Jérôme; Pivovaroff, Alexandria L; Santiago, Louis S; Rolshausen, Philippe E

    2014-01-01

    This review illuminates key findings in our understanding of grapevine xylem resistance to fungal vascular wilt diseases. Grapevine (Vitis spp.) vascular diseases such as esca, botryosphaeria dieback, and eutypa dieback, are caused by a set of taxonomically unrelated ascomycete fungi. Fungal colonization of the vascular system leads to a decline of the plant host because of a loss of the xylem function and subsequent decrease in hydraulic conductivity. Fungal vascular pathogens use different colonization strategies to invade and kill their host. Vitis vinifera cultivars display different levels of tolerance toward vascular diseases caused by fungi, but the plant defense mechanisms underlying those observations have not been completely elucidated. In this review, we establish a parallel between two vascular diseases, grapevine esca disease and Dutch elm disease, and argue that the former should be viewed as a vascular wilt disease. Plant genotypes exhibit differences in xylem morphology and resistance to fungal pathogens causing vascular wilt diseases. We provide evidence that the susceptibility of three commercial V. vinifera cultivars to esca disease is correlated to large vessel diameter. Additionally, we explore how xylem morphological traits related to water transport are influenced by abiotic factors, and how these might impact host tolerance of vascular wilt fungi. Finally, we explore the utility of this concept for predicting which V. vinifera cultivars are most vulnerable of fungal vascular wilt diseases and propose new strategies for disease management.

  11. Gasification of Woody Biomass.

    PubMed

    Dai, Jianjun; Saayman, Jean; Grace, John R; Ellis, Naoko

    2015-01-01

    Interest in biomass to produce heat, power, liquid fuels, hydrogen, and value-added chemicals with reduced greenhouse gas emissions is increasing worldwide. Gasification is becoming a promising technology for biomass utilization with a positive environmental impact. This review focuses specifically on woody biomass gasification and recent advances in the field. The physical properties, chemical structure, and composition of biomass greatly affect gasification performance, pretreatment, and handling. Primary and secondary catalysts are of key importance to improve the conversion and cracking of tars, and lime-enhanced gasification advantageously combines CO2 capture with gasification. These topics are covered here, including the reaction mechanisms and biomass characterization. Experimental research and industrial experience are investigated to elucidate concepts, processes, and characteristics of woody biomass gasification and to identify challenges.

  12. [Bibliometrics of woody medical plants in China].

    PubMed

    Zhang, Guoquan; Si, Jinping; Zhu, Yuqiu

    2010-03-01

    Using the theory and method of bibliometrics, this paper made statistical analysis on the research papers of 16 main woody medical plants published in the period of 1998-2007, from aspects of years distribution, journals distribution, themes distribution, authors distribution and research institutes distribution, and so on. The results showed the studies, status quto and development potential of woody medical plants.

  13. New market potential: Torrefaction of Woody Biomass

    SciTech Connect

    Jaya Shankar Tumuluru; J. Richard Hess

    2015-07-01

    According to researchers in Idaho National Laboratory’s Bioenergy Program, torrefaction of woody biomass could reduce variability in biomass feedstock and enable development of a commodity-type product for green energy generation and usage.

  14. Application of Somatic Embryogenesis in Woody Plants.

    PubMed Central

    Guan, Yuan; Li, Shui-Gen; Fan, Xiao-Fen; Su, Zhen-Hong

    2016-01-01

    Somatic embryogenesis is a developmental process where a plant somatic cell can dedifferentiate to a totipotent embryonic stem cell that has the ability to give rise to an embryo under appropriate conditions. This new embryo can further develop into a whole plant. In woody plants, somatic embryogenesis plays a critical role in clonal propagation and is a powerful tool for synthetic seed production, germplasm conservation, and cryopreservation. A key step in somatic embryogenesis is the transition of cell fate from a somatic cell to embryo cell. Although somatic embryogenesis has already been widely used in a number of woody species, propagating adult woody plants remains difficult. In this review, we focus on molecular mechanisms of somatic embryogenesis and its practical applications in economic woody plants. Furthermore, we propose a strategy to improve the process of somatic embryogenesis using molecular means. PMID:27446166

  15. Determinants of woody cover in African savannas

    USGS Publications Warehouse

    Sankaran, M.; Hanan, N.P.; Scholes, R.J.; Ratnam, J.; Augustine, D.J.; Cade, B.S.; Gignoux, J.; Higgins, S.I.; Le, Roux X.; Ludwig, F.; Ardo, J.; Banyikwa, F.; Bronn, A.; Bucini, G.; Caylor, K.K.; Coughenour, M.B.; Diouf, A.; Ekaya, W.; Feral, C.J.; February, E.C.; Frost, P.G.H.; Hiernaux, P.; Hrabar, H.; Metzger, K.L.; Prins, H.H.T.; Ringrose, S.; Sea, W.; Tews, J.; Worden, J.; Zambatis, N.

    2005-01-01

    Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties 1-3. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover1,2,4,5, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than ???650 mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered 'stable' systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of ???650 mm, savannas are 'unstable' systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation 6 may considerably affect their distribution and dynamics. ?? 2005 Nature Publishing Group.

  16. Determinants of woody cover in African savannas.

    PubMed

    Sankaran, Mahesh; Hanan, Niall P; Scholes, Robert J; Ratnam, Jayashree; Augustine, David J; Cade, Brian S; Gignoux, Jacques; Higgins, Steven I; Le Roux, Xavier; Ludwig, Fulco; Ardo, Jonas; Banyikwa, Feetham; Bronn, Andries; Bucini, Gabriela; Caylor, Kelly K; Coughenour, Michael B; Diouf, Alioune; Ekaya, Wellington; Feral, Christie J; February, Edmund C; Frost, Peter G H; Hiernaux, Pierre; Hrabar, Halszka; Metzger, Kristine L; Prins, Herbert H T; Ringrose, Susan; Sea, William; Tews, Jörg; Worden, Jeff; Zambatis, Nick

    2005-12-08

    Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than approximately 650 mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered 'stable' systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of approximately 650 mm, savannas are 'unstable' systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation may considerably affect their distribution and dynamics.

  17. Frost resistance in alpine woody plants

    PubMed Central

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone. PMID:25520725

  18. Frost resistance in alpine woody plants.

    PubMed

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

  19. Comparative genomics reveals genes significantly associated with woody hosts in the plant pathogen Pseudomonas syringae

    PubMed Central

    Laue, Bridget E.; Sharp, Paul M.; Green, Sarah

    2016-01-01

    Summary The diversification of lineages within Pseudomonas syringae has involved a number of adaptive shifts from herbaceous hosts onto various species of tree, resulting in the emergence of highly destructive diseases such as bacterial canker of kiwi and bleeding canker of horse chestnut. This diversification has involved a high level of gene gain and loss, and these processes are likely to play major roles in the adaptation of individual lineages onto their host plants. In order to better understand the evolution of P. syringae onto woody plants, we have generated de novo genome sequences for 26 strains from the P. syringae species complex that are pathogenic on a range of woody species, and have looked for statistically significant associations between gene presence and host type (i.e. woody or herbaceous) across a phylogeny of 64 strains. We have found evidence for a common set of genes associated with strains that are able to colonize woody plants, suggesting that divergent lineages have acquired similarities in genome composition that may form the genetic basis of their adaptation to woody hosts. We also describe in detail the gain, loss and rearrangement of specific loci that may be functionally important in facilitating this adaptive shift. Overall, our analyses allow for a greater understanding of how gene gain and loss may contribute to adaptation in P. syringae. PMID:27145446

  20. 48 CFR 1452.237-71 - Utilization of Woody Biomass.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Biomass. 1452.237-71 Section 1452.237-71 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR... Utilization of Woody Biomass. As prescribed in § 1437.7202, insert the following clause: Utilization of Woody Biomass (MAY 2005) (a) The contractor may remove and utilize woody biomass, if: (1) Project work...

  1. 48 CFR 1452.237-71 - Utilization of Woody Biomass.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Biomass. 1452.237-71 Section 1452.237-71 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR... Utilization of Woody Biomass. As prescribed in § 1437.7202, insert the following clause: Utilization of Woody Biomass (MAY 2005) (a) The contractor may remove and utilize woody biomass, if: (1) Project work...

  2. 48 CFR 1452.237-71 - Utilization of Woody Biomass.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Biomass. 1452.237-71 Section 1452.237-71 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR... Utilization of Woody Biomass. As prescribed in § 1437.7202, insert the following clause: Utilization of Woody Biomass (MAY 2005) (a) The contractor may remove and utilize woody biomass, if: (1) Project work...

  3. 48 CFR 1452.237-71 - Utilization of Woody Biomass.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Biomass. 1452.237-71 Section 1452.237-71 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR... Utilization of Woody Biomass. As prescribed in § 1437.7202, insert the following clause: Utilization of Woody Biomass (MAY 2005) (a) The contractor may remove and utilize woody biomass, if: (1) Project work...

  4. 48 CFR 1452.237-71 - Utilization of Woody Biomass.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Biomass. 1452.237-71 Section 1452.237-71 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR... Utilization of Woody Biomass. As prescribed in § 1437.7202, insert the following clause: Utilization of Woody Biomass (MAY 2005) (a) The contractor may remove and utilize woody biomass, if: (1) Project work...

  5. Coarse woody debris dynamics in two old-growth ecosystems

    SciTech Connect

    Harmon, M.E. ); Chen Hua )

    1991-10-01

    In this article, the dynamics of coarse woody debris are compound deciduous old-growth forest system Changbai Mountain Biosphere Reserve in China, and a coniferous old-growth forest system, H. J. Andrews Experimental Forest in Oregon. The objective is to compare in these two ecosystems the amount of coarse woody debris; the processes that affect coarse woody debris, such as tree mortality and decay rates; and the role of coarse woody debris in nutrient cycling. To assess importance in the global carbon budget, these two old-growth ecosystems are used to estimate the upper and lower limits of coarse woody debris mass for undisturbed temperate forests.

  6. THE INTAKE OF FIBER MESOCARP PASSIONFRUIT (PASSIFLORA EDULIS) LOWERS LEVELS OF TRIGLYCERIDE AND CHOLESTEROL DECREASING PRINCIPALLY INSULIN AND LEPTIN

    PubMed Central

    Corrêa, E.M.; Medina, L.; Barros-Monteiro, J.; Valle, N.O.; Sales, R.; Magalães, A.; Souza, F.C.A.; Carvalho, T.B.; Lemos, J.R.; Lira, E.F.; Lima, E.S.; Galeno, D.M.L.; Morales, L.; Ortiz, C.; Carvalho, R.P.

    2014-01-01

    Background Diabetes mellitus (DM) is a major risk factor for coronary artery disease, renal failure, retinopathy, and neuropathy. Over the last years, there has been an increasing demand in folk medicine for natural sources that could help in the treatment of chronic diseases, including diabetes. The rind of passion fruit (Passiflora edulis f. Flavicarpa) is traditionally used as a functional food due to its high concentration of soluble and insoluble fiber. Objective The aim of this study was to determine the effect of high-fiber diet albedo of passion fruit on the metabolic and biochemical profile in diabetic rats induced by alloxan (2%). Design The passion fruit mesocarp fiber was dried in an oven with circulating air at 60°C and pulverized. We used 32 adult male rats, divided into 4 groups: Wistar group 1 control (GC), Wistar group 2, 15% fiber (GF15), Wistar group 3, 30% fiber (GF30), Wistar group 4, fiber disolved in water (GFH2O). The ratio of passion fruit was prepared according to the AIN 93M guidelines, varying only the source of dietary fiber. The corresponding diet for each group was offered to the animals for 60 days. Results There was a statically significant decrease in plasma glucose for GFH2O, GF15%, and GF30% groups with 27.0%, 37.4%, and 40.2%, respectively. Conclusion The use of mesocarp fiber of passion fruit at concentrations of 15% and 30% are an important dietary supplement for the treatment of DM due to its potential hypoglycemic effect, and its ability to reduce triglycerides and VLDL-cholesterol levels with a principal reduction of insulin and leptin. PMID:25346913

  7. Woodiness within the Spermacoceae–Knoxieae alliance (Rubiaceae): retention of the basal woody condition in Rubiaceae or recent innovation?

    PubMed Central

    Lens, Frederic; Groeninckx, Inge; Smets, Erik; Dessein, Steven

    2009-01-01

    Background and Aims The tribe Spermacoceae is essentially a herbaceous Rubiaceae lineage, except for some species that can be described as ‘woody’ herbs, small shrubs to treelets, or lianas. Its sister tribe Knoxieae contains a large number of herbaceous taxa, but the number of woody taxa is higher compared to Spermacoceae. The occurrence of herbaceous and woody species within the same group raises the question whether the woody taxa are derived from herbaceous taxa (i.e. secondary woodiness), or whether woodiness represents the ancestral state (i.e. primary woodiness). Microscopic observations of wood anatomy are combined with an independent molecular phylogeny to answer this question. Methods Observations of wood anatomy of 21 woody Spermacoceae and eight woody Knoxieae species, most of them included in a multi-gene molecular phylogeny, are carried out using light microscopy. Key Results Observations of wood anatomy in Spermacoceae support the molecular hypothesis that all the woody species examined are secondary derived. Well-known wood anatomical characters that demonstrate this shift from the herbaceous to the woody habit are the typically flat or decreasing length vs. age curves for vessel elements, the abundance of square and upright ray cells, or even the (near-) absence of rays. These so-called paedomorphic wood features are also present in the Knoxieae genera Otiophora, Otomeria, Pentas, Pentanisia and Phyllopentas. However, the wood structure of the other Knoxieae genera observed (Carphalea, Dirichletia and Triainolepis) is typical of primarily woody taxa. Conclusions In Spermacoceae, secondary woodiness has evolved numerous times in strikingly different habitats. In Knoxieae, there is a general trend from primary woodiness towards herbaceousness and back to (secondary) woodiness. PMID:19279041

  8. Woody Debris in the mangrove forests of South Florida

    USGS Publications Warehouse

    Krauss, K.W.; Doyle, T.W.; Twilley, R.R.; Smith, T. J.; Whelan, K.R.T.; Sullivan, J.K.

    2005-01-01

    Woody debris is abundant in hurricane-impacted forests. With a major hurricane affecting South Florida mangroves approximately every 20 yr, carbon storage and nutrient retention may be influenced greatly by woody debris dynamics. In addition, woody debris can influence seedling regeneration in mangrove swamps by trapping propagules and enhancing seedling growth potential. Here, we report on line-intercept woody debris surveys conducted in mangrove wetlands of South Florida 9-10 yr after the passage of Hurricane Andrew. The total volume of woody debris for all sites combined was estimated at 67 m 3/ha and varied from 13 to 181 m3/ha depending upon differences in forest height, proximity to the storm, and maximum estimated wind velocities. Large volumes of woody debris were found in the eyewall region of the hurricane, with a volume of 132 m3/ha and a projected woody debris biomass of approximately 36 t/ha. Approximately half of the woody debris biomass averaged across all sites was associated as small twigs and branches (fine woody debris), since coarse woody debris >7.5 cm felled during Hurricane Andrew was fairly well decomposed. Much of the small debris is likely to be associated with post-hurricane forest dynamics. Hurricanes are responsible for large amounts of damage to mangrove ecosystems, and components of associated downed wood may provide a relative index of disturbance for mangrove forests. Here, we suggest that a fine:coarse woody debris ratio ???0.5 is suggestive of a recent disturbance in mangrove wetlands, although additional research is needed to corroborate such findings.

  9. Early deterioration of coarse woody debris.

    SciTech Connect

    Tainter, Frank, H.; McMinn, James, W.

    1999-02-16

    Tainter, F.H., and J.W. McMinn. 1999. Early deterioration of coarse woody debris. In: Proc. Tenth Bien. South. Silv. Res. Conf. Shreveport, LA, February 16-18, 1999. Pp. 232-237 Abstract - Coarse woody debris (CWD) is an important structural component of southern forest ecosystems. CWD loading may be affected by different decomposition rates on sites of varying quality. Bolts of red oak and loblolly pine were placed on plots at each of three (hydric, mesic. and xerlc) sites at the Savannah River Site and sampled over a I6-week period. Major changes were in moisture content and nonstructural carbohydrate content (total carbohydrates, reducing sugars, and starch) of sapwood. Early changes in nonstructural carbohydrate levels following placement of the bolts were likely due to reallocation of these materials by sapwood parenchyma cells. These carbohydrates later formed pools increasingly metabolized by bacteria and invading fungi. Most prevalent fungi in sapwood were Ceratocysfis spp. in pine and Hypoxy/on spp. in oak. Although pine sapwood became blue stained and oak sapwood exhibited yellow soft decay with black zone lines, estimators of decay (specific gravity, sodium hydroxide solubility, and holocellulose content) were unchanged during the 16-week study period. A small effect of site was detected for starch content of sapwood of both species. Fungal biomass in sapwood of both species, as measured by ergosterol content, was detectable at week zero, increased somewhat by week three and increased significantly by week 16.

  10. Short Rotation Woody Crops Program: Project summaries

    SciTech Connect

    Not Available

    1986-11-01

    This document is a compilation of summaries describing research efforts in the US Department of Energy's Short Rotation Woody Crops Program (SRWCP). The SRWCP is sponsored by DOE's Biofuels and Municipal Waste Technology Division and is field-managed at Oak Ridge National Laboratory. The SRWCP is an integrated basic research program with 18 field research projects throughout the United States. The overall objective of the program is to improve the productivity and increase the cost efficiency of growing and harvesting woody trees and shrubs. In a competitive technical review, 25 projects were chosen to form a new research program. Although some of the original projects have ended and new ones have begun, many of the long-term research projects still form the core of the SRWCP. This document contains individual summaries of each of the 18 research projects in the SRWCP from October 1985 to October 1986. Each summary provides the following information: name and address of the contracting institution, principal investigator, project title, current subcontract or grant number, period of performance, and annual funding through fiscal year 1986. In addition, each summary contains a brief description of the project rationale, objective, approach, status, and future efforts. A list of publications that have resulted from DOE-sponsored research follows many of the summaries.

  11. Determinants of woody encroachment and cover in African savannas.

    PubMed

    Devine, Aisling P; McDonald, Robbie A; Quaife, Tristan; Maclean, Ilya M D

    2017-04-01

    Savanna ecosystems are an integral part of the African landscape and sustain the livelihoods of millions of people. Woody encroachment in savannas is a widespread phenomenon but its causes are widely debated. We review the extensive literature on woody encroachment to help improve understanding of the possible causes and to highlight where and how future scientific efforts to fully understand these causes should be focused. Rainfall is the most important determinant of maximum woody cover across Africa, but fire and herbivory interact to reduce woody cover below the maximum at many locations. We postulate that woody encroachment is most likely driven by CO2 enrichment and propose a two-system conceptual framework, whereby mechanisms of woody encroachment differ depending on whether the savanna is a wet or dry system. In dry savannas, the increased water-use efficiency in plants relaxes precipitation-driven constraints and increases woody growth. In wet savannas, the increase of carbon allocation to tree roots results in faster recovery rates after disturbance and a greater likelihood of reaching sexual maturity. Our proposed framework can be tested using a mixture of experimental and earth observational techniques. At a local level, changes in precipitation, burning regimes or herbivory could be driving woody encroachment, but are unlikely to be the explanation of this continent-wide phenomenon.

  12. Woody Vegetation on Levees? - Research Experiences and Design Suggestions

    NASA Astrophysics Data System (ADS)

    Lammeranner, Walter

    2013-04-01

    Recent flood events in Austria have reawakened practical and scientific interest in the stability of levees. One focus amongst others has been taken on the relationship between vegetation and levee stability with special reference to the role of woody plants. The effects of woody plants are undoubtedly manifold: On the one hand they can potentially have a negative influence and endanger levees, which is why many guidelines ban woody vegetation to preserve stability, visual inspection and unhindered flood-fight access. On the other hand woody vegetation can have several positive impacts on soil stability and which effects prevail depends largely on types and characteristics of plants. This shows how controversially woody plants on levees can be discussed and the strong need for further research in this field. In order to obtain new insights and widen horizons for this controversial issue, a research project carried out by the Institute of Soil Bioengineering and Landscape Construction - at the University of Natural Resources and Life Sciences, Vienna - was launched. This project deals with several aspects of effects of woody plants have on levees and focuses particularly on shrubby woody plants. The examined vegetation type is a dense stand of willows - Purple-Willows (Salix purpurea L.) - commonly used for stabilization of river embankments. The proposed contribution discusses the gained results with reference to levee stability and existing levee vegetation guidelines and gives design suggestions for compatible woody vegetation on levees.

  13. Pyrolysis of Woody Residues: Impact of Mineral Content

    SciTech Connect

    Iisa, Kristiina; Zacher, Alan; Sykes, Robert; Preto, Fernando; Bronson, Benjamin

    2014-11-21

    Woody residues represent a lower cost option for feedstocks for the production of biofuels. In this study, the pyrolysis of woody residues was investigated as part of Clean Energy Dialogue between the U.S. and Canada. Three pine-based hog fuels from saw mills and wood from pine beetle killed trees were chosen as the woody residue feedstocks and pine and birch as the reference clean feedstocks. The yields and quality of the oil were evaluated in a bubbling fluidized bed reactor and a laboratory-scale pyrolyzer connected to a molecular beam mass spectrometer.

  14. Quantifying the resistance of woody debris in natural streams

    NASA Astrophysics Data System (ADS)

    Clancy, K. A.

    2013-12-01

    Discharge is one of the most important natural stream variables affecting a system's ecology, water quality, hydroelectric power, and navigation. Hydrologists commonly use the friction factor equation to estimate water discharge in ungaged streams. In natural streams the equation does not accurately predict discharge in streams with woody debris and vegetation. The objective of this project is to develop a refined method of incorporating woody debris components, commonly found in natural streams, into the friction factor equation, resulting in a more accurate discharge estimation. Ten gaged gravel bed streams with 30% woody debris were surveyed. Discharge was measured and compared to values given by the friction factor. By incorporating a woody debris factor into the equation, discharge estimates match measured values closer by over twenty percent.

  15. Aluminum exclusion and aluminum tolerance in woody plants

    PubMed Central

    Brunner, Ivano; Sperisen, Christoph

    2013-01-01

    The aluminum (Al) cation Al3+ is highly rhizotoxic and is a major stress factor to plants on acid soils, which cover large areas of tropical and boreal regions. Many woody plant species are native to acid soils and are well adapted to high Al3+ conditions. In tropical regions, both woody Al accumulator and non-Al accumulator plants occur, whereas in boreal regions woody plants are non-Al accumulators. The mechanisms of these adaptations can be divided into those that facilitate the exclusion of Al3+ from root cells (exclusion mechanisms) and those that enable plants to tolerate Al3+ once it has entered the root and shoot symplast (internal tolerance mechanisms). The biochemical and molecular basis of these mechanisms have been intensively studied in several crop plants and the model plant Arabidopsis. In this review, we examine the current understanding of Al3+ exclusion and tolerance mechanisms from woody plants. In addition, we discuss the ecology of woody non-Al accumulator and Al accumulator plants, and present examples of Al3+ adaptations in woody plant populations. This paper complements previous reviews focusing on crop plants and provides insights into evolutionary processes operating in plant communities that are widespread on acid soils. PMID:23781222

  16. Phloem exudation studies in selected woody trees

    SciTech Connect

    Costello, L.R.

    1980-10-01

    Chelating agents, particularly EDTA, were tested for their effectiveness in enhancing the exudation of phloem sugars from selected woody tree species. Of the species selected, Fraxinus uhdei (Evergreen Ash) proved most useful for exudation studies. Experiments using /sup 14/C labelled, excised leaflets of F. uhdei demonstrated that exudation was enhanced approximately 9-fold by a 2.0 mM EDTA treatment. An analysis of labelled products in the treatment solution showed that over 90% of label appeared in oligosaccharides and sucrose. These findings suggested that the sugars released into EDTA treatment solutions were principally derived from phloem sieve elements. Electron microscope studies of the fine structure of sieve plate pores after treatment with EDTA or H/sub 2/O showed substantially less callose appearing in sieve plates of leaflets treated with EDTA. It was proposed that EDTA enhances exudation by inhibiting or reducing callose formation in sieve plate pores. Subsequent experiments demonstrated that EDTA was effective in promoting exudation from whole plant specimens of F. uhdei as well as from excised leaflets. (MHR)

  17. Extreme low temperature tolerance in woody plants

    PubMed Central

    Strimbeck, G. Richard; Schaberg, Paul G.; Fossdal, Carl G.; Schröder, Wolfgang P.; Kjellsen, Trygve D.

    2015-01-01

    Woody plants in boreal to arctic environments and high mountains survive prolonged exposure to temperatures below -40°C and minimum temperatures below -60°C, and laboratory tests show that many of these species can also survive immersion in liquid nitrogen at -196°C. Studies of biochemical changes that occur during acclimation, including recent proteomic and metabolomic studies, have identified changes in carbohydrate and compatible solute concentrations, membrane lipid composition, and proteins, notably dehydrins, that may have important roles in survival at extreme low temperature (ELT). Consideration of the biophysical mechanisms of membrane stress and strain lead to the following hypotheses for cellular and molecular mechanisms of survival at ELT: (1) Changes in lipid composition stabilize membranes at temperatures above the lipid phase transition temperature (-20 to -30°C), preventing phase changes that result in irreversible injury. (2) High concentrations of oligosaccharides promote vitrification or high viscosity in the cytoplasm in freeze-dehydrated cells, which would prevent deleterious interactions between membranes. (3) Dehydrins bind membranes and further promote vitrification or act stearically to prevent membrane–membrane interactions. PMID:26539202

  18. Acetylation of woody lignocellulose: significance and regulation

    PubMed Central

    Pawar, Prashant Mohan-Anupama; Koutaniemi, Sanna; Tenkanen, Maija; Mellerowicz, Ewa J.

    2013-01-01

    Non-cellulosic cell wall polysaccharides constitute approximately one quarter of usable biomass for human exploitation. In contrast to cellulose, these components are usually substituted by O-acetyl groups, which affect their properties and interactions with other polymers, thus affecting their solubility and extractability. However, details of these interactions are still largely obscure. Moreover, polysaccharide hydrolysis to constituent monosaccharides is hampered by the presence of O-acetyl groups, necessitating either enzymatic (esterase) or chemical de-acetylation, increasing the costs and chemical consumption. Reduction of polysaccharide acetyl content in planta is a way to modify lignocellulose toward improved saccharification. In this review we: (1) summarize literature on lignocellulose acetylation in different tree species, (2) present data and current hypotheses concerning the role of O-acetylation in determining woody lignocellulose properties, (3) describe plant proteins involved in lignocellulose O-acetylation, (4) give examples of microbial enzymes capable to de-acetylate lignocellulose, and (5) discuss prospects for exploiting these enzymes in planta to modify xylan acetylation. PMID:23734153

  19. Can lemmings control the expansion of woody plants on tundra?

    NASA Astrophysics Data System (ADS)

    Oksanen, Lauri; Oksanen, Tarja; Olofsson, Johan; Virtanen, Risto; Hoset, Katrine; Tuomi, Maria; Kyrö, Kukka

    2013-04-01

    The ongoing expansion of woody vegetation in the arctic, due to global warming, creates a positive feed back loop. Increasing abundance of woody plants reduces surface albedo both directly and via speeding up snow melt. Thus a successively greater fraction of incoming solar radiation is absorbed and converted to heat. Browsing mammals - both big and small - can prevent this by consuming woody plants. However, the grazer/browser community of many tundra areas is dominated by brown/Norwegian lemmings (Lemmus spp.) which eat graminoids and mosses and cannot use woody plants as forage. It would seem a priori likely that in such areas, mammalian herbivores speed up the expansion of woody plants by improving the chances of their seedlings to get established. We studied the impact of lemmings on woody plants by constructing lemming proof exclosures within piece high-altitude tundra at Joatkanjávri, northernmost Norway. The exclosures were constructed in 1998, during a period of low lemming densities, in snow-beds, where Norwegian lemmings (L. lemmus) were the only ecologically significant herbivorous mammals. (Reindeer migrate through the area in May, when snow-beds are inaccessible for them; during the fall migration, the area represents a dead end and is therefore avoided.) We chose pairs of maximally similar vegetation patches of 0.5 by 0.5 m and randomly assigned one of each pair to become an exclosure while the other plot was left open. The initial state of the vegetation was documented by the point frequency method. In 2008, after the 2007 lemming outbreak, the same documentation was repeated; thereafter the plots were harvested, the vegetation was sorted to species, oven dried and weighed. Exclusion of lemmings resulted to pronounced increase in community level plant biomass. Evergreen woody plants were especially favored by the exclusion of lemming: their above-ground biomass in exclosures was 14 times as great as their biomass on open reference plots. The

  20. Evaluating Ecohydrological Theories of Woody Root Distribution in the Kalahari

    PubMed Central

    Bhattachan, Abinash; Tatlhego, Mokganedi; Dintwe, Kebonye; O'Donnell, Frances; Caylor, Kelly K.; Okin, Gregory S.; Perrot, Danielle O.; Ringrose, Susan; D'Odorico, Paolo

    2012-01-01

    The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1) the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis), and (2) the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis). Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity. PMID:22470506

  1. Measuring Biomass and Carbon Stock in Resprouting Woody Plants

    PubMed Central

    Matula, Radim; Damborská, Lenka; Nečasová, Monika; Geršl, Milan; Šrámek, Martin

    2015-01-01

    Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation. PMID:25719601

  2. CBTL Design Case Summary Conventional Feedstock Supply System - Woody

    SciTech Connect

    Christopher T. Wright; Erin M. Searcy

    2012-02-01

    A conventional woody feedstock design has been developed that represents supply system technologies, costs, and logistics that are achievable today for supplying woody biomass as a blendstock with coal for energy production. Efforts are made to identify bottlenecks and optimize the efficiency and capacities of this supply system, within the constraints and consideration of existing local feedstock supplies, equipment, and permitting requirements. The feedstock supply system logistics operations encompass all of the activities necessary to move woody biomass from the production location to the conversion reactor ready for blending and insertion. This supply system includes operations that are currently available such that costs and logistics are reasonable and reliable. The system modeled for this research project includes the use of the slash stream since it is a more conservative analysis and represents the material actually used in the experimental part of the project.

  3. Postscript: Problems With the Security Motivation Model Remain Largely Unresolved: Response to Woody and Szechtman (2005)

    ERIC Educational Resources Information Center

    Taylor, Steven; McKay, Dean; Abramowitz, Jonathan S.

    2005-01-01

    This paper comments on the response offered by Szechtman and Woody to Taylor et al's initial comments on Szechtman and Woody's original article. Taylor et al highlight one problem with their model that Woody and Szechtman seem to think is unimportant: the treatment relevance of their model. The analogy of aspirin and colds was used, suggesting…

  4. Spatial vegetation patterns and neighborhood competition among woody plants in an East African savanna

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The majority of research on savanna vegetation dynamics has focused on the coexistence of woody and herbaceous vegetation; interactions among woody plants in savannas are relatively poorly understood. We present data from a 10-year longitudinal study of spatially explicit growth patterns of woody ve...

  5. 75 FR 76695 - Request for Proposals for 2011 Woody Biomass Utilization Grant Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-09

    ... nationwide challenge of using low-value woody biomass material to create renewable energy. Goals of the grant... biomass for renewable energy. Assist projects that produce renewable energy from woody biomass. Reduce... business risk to increase use of woody biomass from our nation's forestlands for renewable energy...

  6. 78 FR 11622 - Request for Proposals: 2013 Hazardous Fuels Woody Biomass Utilization Grant Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-19

    ... ] nationwide challenge of using low-value woody biomass material to create renewable energy and protect... that target and help remove economic and market barriers to using woody biomass for renewable energy. Assist projects that produce renewable energy from woody biomass while protecting the public...

  7. 77 FR 5755 - Request for Proposals: 2012 Hazardous Fuels Woody Biomass Utilization Grant Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-06

    ... using low-value woody biomass material to create renewable energy and protect communities and critical... economic and market barriers to using woody biomass for renewable energy. Assist projects that produce renewable energy from woody biomass while protecting the public interest. Reduce the public's cost...

  8. Assessing the Effects of Woody Plant Traits on Understory Herbaceous Cover in a Semiarid Rangeland

    NASA Astrophysics Data System (ADS)

    Belay, Tamrat A.; Moe, Stein R.

    2015-07-01

    The ecological impact of woody plant encroachment in rangeland ecosystems has traditionally been evaluated based on correlation studies between densities of dissimilar woody plants and various ecosystem properties. However, ecosystem properties respond differently to woody plant encroachment because of variations in adaptation of co-occurring woody plants. The objective of this study is to predict the impact of woody plant encroachment on understory herbaceous cover based on analysis of key traits of woody plants. We conducted a vegetation survey in 4 savanna sites in southwestern Ethiopia and compared 9 different key traits of 19 co-occurring woody plants with understory herbaceous cover. Our results show that low understory herbaceous cover is associated with evergreen leaf phenology, shrubby growth form, smaller relative crown-base height and larger relative crown diameter. However, the N2-fixing ability and density of woody plants did not influence the understory herbaceous cover. This shows that traits of individual woody plants can predict the impact of woody plant encroachment on understory herbaceous cover better than density does. The finding improves our ability to accurately predict the impact of woody plant encroachment on various ecosystem properties in highly diverse savanna systems. This plant trait-based approach could be also used as an important management exercise to assess and predict the impact of encroaching woody species in several rangeland ecosystems.

  9. Does livestock grazing influence spatial patterns of woody plant proliferation?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Patterns of woody plant proliferation in grasslands and savannas influence rates of erosion, spread of disturbance, and nutrient pools.  Spatial pattern is the outcome of plant dispersal, recruitment, competition/facilitation, and disturbance. We quantified effects of livestock grazing, a widely cit...

  10. Interactions of Woody Biofuel Feedstock Production Systems with Water Resources: Considerations for Sustainability

    SciTech Connect

    Trettin, Carl C.; Amatya, Devendra; Coleman, Mark

    2008-04-15

    Water resources are important for the production of woody biofuel feedstocks. It is necessary to ensure that production systems do not adversely affect the quantity or quality of surface and ground water. The effects of woody biomass plantations on water resources are largely dependent on the prior land use and the management regime. Experience from both irrigated and non-irrigated systems has demonstrated that woody biofuel production systems do not impair water quality. Water quality actually improves from conversion of idle or degraded agricultural lands to woody biomass plantations. Site water balance may be altered by cultivation of woody biomass plantations relative to agricultural use, due to increases in evapostranspiration (ET) and storage. Incorporation of woody biomass production plantations within the landscape provides an opportunity to improve the quality of runoff water and soil conservation. Finally, given the centrality of water resources to the sustainability of ecosystem services and other values derived, the experience with woody biofuels feedstock production systems is positive.

  11. Botryosphaeria dothidea: a latent pathogen of global importance to woody plant health.

    PubMed

    Marsberg, Angelica; Kemler, Martin; Jami, Fahimeh; Nagel, Jan H; Postma-Smidt, Alisa; Naidoo, Sanushka; Wingfield, Michael J; Crous, Pedro W; Spatafora, Joseph W; Hesse, Cedar N; Robbertse, Barbara; Slippers, Bernard

    2016-09-28

    Botryosphaeria dothidea is the type species of Botryosphaeria (Botryosphaeriaceae, Botryosphaeriales). Fungi residing in this order are amongst the most widespread and important canker and dieback pathogens of trees worldwide, with B. dothidea one of the most common species on a large number of hosts. Its taxonomic circumscription has undergone substantial change in the past decade, making it difficult to interpret the large volume of literature linked to the name B. dothidea. This pathogen profile synthesizes the current understanding of B. dothidea pertaining to its distribution, host associations and role as a pathogen in managed and natural woody environments. The prolonged latent infection or endophytic phase is of particular importance, as it implies that the fungus can easily pass undetected by quarantine systems in traded living plants, fruits and other plant parts. Infections typically become obvious only under conditions of host stress, when disease symptoms develop. This study also considers the knowledge emerging from the recently sequenced B. dothidea genome, elucidating previously unknown aspects of the species, including mating and host infection strategies. Despite more than 150 years of research on B. dothidea, there is clearly much to be learned regarding this global tree pathogen. This is increasingly important given the stresses imposed on various woody hosts as a result of climate change.

  12. Suitable utilization of woody plants for hibitation on Mars

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Abe, Yusuke; Katayama, Takeshi

    2016-07-01

    We have been investigating the usefulness of woody plants for habitation on Mars. During our research, we have found that woody plants have several properties which can be utilized for therapy and materials for enrage and construction even on Mars. Japanese people traditionally believe that "Bonsai" have therapeudic properties. Trees can become carbon fuel which can be used as energy on Mars. Tree materials could be used as a tool in closed bio-ecosystems such as for the purification and/or separation of solutions in an environment in space. Here, we will show some results of their abilities, the water leakage and vacuum seal test, separation of solutions using carbon materials made from trees. At the initiation of this research, we named the trees used as material for the experiment related to space environments "CosmoBon", small bonsai tree. To establish our research, as the first step, we will try to do the experiment using "CosmoBon".

  13. [Research advance in seed germination of desert woody plants].

    PubMed

    Chang, Wei; Wu, Jian-guo; Liu, Yan-hong

    2007-02-01

    This paper reviewed the research methods of desert woody plants seed germination, and the effects of internal and external ecological factors on it. Most researchers use incubator and artificial climate chamber to dispose the seeds, while field investigation was few involved. Seed dormancy is the important physiological factor affecting germination, while seed size, mass and color are closely correlated with its maturity and vigor. The poor permeability of seed capsule is a barrier that restrains the germination, which can be weakened or eliminated by shaving, cutting, treating with low temperature, and dipping in chemical reagent, etc. Seed water content has a close correlation with its storage life and water-absorbing capability. Suitable temperature is the prerequisite of seed germination, while changing temperature can accelerate the germination. Soil moisture content is a limiting factor, while illumination is not so essential to the seed germination of most desert woody plants. Sand-burying plays an important role in the seed germination through regulating illumination, temperature, and soil moisture content. Salinity stress restrains the seed germination of desert woody plants observably. In further studies, the effects of multi-factors and the eco-physiological and molecular biological mechanisms of germination should be more concerned.

  14. Supply of large woody debris in a stream channel

    USGS Publications Warehouse

    Diehl, Timothy H.; Bryan, Bradley A.

    1993-01-01

    The amount of large woody debris that potentially could be transported to bridge sites was assessed in the basin of the West Harpeth River in Tennessee in the fall of 1992. The assessment was based on inspections of study sites at 12 bridges and examination of channel reaches between bridges. It involved estimating the amount of woody material at least 1.5 meters long, stored in the channel, and not rooted in soil. Study of multiple sites allowed estimation of the amount, characteristics, and sources of debris stored in the channel, and identification of geomorphic features of the channel associated with debris production. Woody debris is plentiful in the channel network, and much of the debris could be transported by a large flood. Tree trunks with attached root masses are the dominant large debris type. Death of these trees is primarily the result of bank erosion. Bank instability seems to be the basin characteristic most useful in identifying basins with a high potential for abundant production of debris.

  15. Sensitivity to zinc of Mediterranean woody species important for restoration.

    PubMed

    Disante, Karen B; Fuentes, David; Cortina, Jordi

    2010-04-15

    Heavy metals have increased in natural woodlands and shrublands over the last several decades as a consequence of anthropogenic activities. However, our knowledge of the effects of these elements on woody species is scarce. In this study, we examined the responses of six Mediterranean woody species to increasing levels of zinc in hydroponic culture and discussed the possible implications for the restoration of contaminated sites. The species used, Pinus pinea L., Pinus pinaster Ait., Pinus halepensis Mill., Tetraclinis articulata (Vahl) Mast., Rhamnus alaternus L. and Quercus suber L. represent a climatic gradient from dry sub-humid to semi-arid conditions. Zinc concentrations in shoots ranged from 53 microg g(-1) in Q. suber to 382 microg g(-1) in T. articulata and were well below the levels found in roots. Zinc inhibited root elongation and root biomass and changed the root length distribution per diameter class, but the magnitude of the effects was species-specific. Only P. halepensis and Q. suber showed toxicity symptoms in aboveground parts. Species more characteristic from xeric environments (T. articulata, R. alaternus and P. halepensis) were more sensitive to zinc than species from mesic environments (Q. suber, P. pinaster and P. pinea). According to the Zn responses and bioaccumulation, Q. suber P. pinea and P. halepensis are the best candidates for field trials to test the value of woody species to restore contaminated sites. None of the species tested seemed suitable for phytoremediation.

  16. Briquettability of lignite and woody wastes composite fuel

    SciTech Connect

    Beker, U.G.

    2000-03-01

    Woody wastes have favorable burning characteristics compared to lignite, as well as low ash content and reduced smoke emission. The aim of this study was to blend lignite with woody wastes to obtain a solid fuel that retains the advantageous characteristics of woody materials. Blends with lignite were made up with 7, 9, 12, 15, and 20% of waste and then briquetted under pressures of 400, 550, 700, and 800 MPa. Sunflower shell, sawdust, and paper mill wastes were used in different amounts with molasses as binder. Studies were carried out on a laboratory scale to determine optimum parameters for briquetting, such as moisture content of lignite and pressure. Briquetting of lignite without waste materials produces products of low strength. The strongest briquettes were obtained with waste contents of 12--20% and lignite moisture contents of 10--12% at briquetting pressures of 550, 700, and 800 MPa. Briquettes with adequate mechanical strength are obtained from lignite-waste blends with the addition of 8% molasses.

  17. Spatial vegetation patterns and neighborhood competition among woody plants in an East African savanna.

    PubMed

    Dohn, Justin; Augustine, David J; Hanan, Niall P; Ratnam, Jayashree; Sankaran, Mahesh

    2017-02-01

    The majority of research on savanna vegetation dynamics has focused on the coexistence of woody and herbaceous vegetation. Interactions among woody plants in savannas are relatively poorly understood. We present data from a 10-yr longitudinal study of spatially explicit growth patterns of woody vegetation in an East African savanna following exclusion of large herbivores and in the absence of fire. We examined plant spatial patterns and quantified the degree of competition among woody individuals. Woody plants in this semiarid savanna exhibit strongly clumped spatial distributions at scales of 1-5 m. However, analysis of woody plant growth rates relative to their conspecific and heterospecific neighbors revealed evidence for strong competitive interactions at neighborhood scales of up to 5 m for most woody plant species. Thus, woody plants were aggregated in clumps despite significantly decreased growth rates in close proximity to neighbors, indicating that the spatial distribution of woody plants in this region depends on dispersal and establishment processes rather than on competitive, density-dependent mortality. However, our documentation of suppressive effects of woody plants on neighbors also suggests a potentially important role for tree-tree competition in controlling vegetation structure and indicates that the balanced-competition hypothesis may contribute to well-known patterns in maximum tree cover across rainfall gradients in Africa.

  18. Mycorrhizal Productivity Following Woody Plant Invasion of Grassland

    NASA Astrophysics Data System (ADS)

    Boutton, T. W.; Rowe, H. I.; Ariza, M. C.; Miller, R. M.; Filley, T. R.

    2008-12-01

    Mycorrhizal fungi play an important role in soil carbon storage and dynamics through the production of recalcitrant organic compounds (e.g., glomalin and chitin), and through the production of hyphae which entangle and enmesh soil particles to form aggregates which physically protect organic matter from decomposer organisms. Despite these important functions, little is known regarding rates of mycorrhizal productivity and how these rates might be influenced by changes in plant community composition. We quantified mycorrhizal production in a subtropical savanna parkland in southern Texas where woody plants have invaded areas that were once open grassland. Mycorrhizal ingrowth bags (3 x 10 cm) were made from 50 μm nylon mesh, filled with sterile sand (200-600 μm particle size), and deployed in the field in triplicate in remnant grasslands (n=15), and in woody plant stands (n=13) ranging in age from 15 to 86 yrs. Ingrowth bags were installed in May and harvested in Oct 2007 after 156 days. Hyphae were isolated by flotation/filtration, cleaned thoroughly to remove sand, freeze-dried, and weighed. Microscopic examination indicated that nearly all hyphae recovered from ingrowth bags were from arbuscular mycorrhizal fungi. During the ingrowth period, nearly 4X more hyphal biomass accumulated in wooded areas (9.00 ± 3.84 g m- 2) compared to remnant grasslands (2.35 ± 0.56 g m-2). Hyphal productivity rates increased linearly with woody plant stand age (r = 0.89) from 15 ± 4 mg m-2 day-1 in grasslands (time 0) up to 58-98 mg m-2 day-1 in wooded areas >65 yrs old. When these productivity rates are annualized, we find that hyphal productivity represents approximately 4% of aboveground net primary productivity (ANPP) in wooded areas, and 2% of ANPP in remnant grasslands. These observations are consistent with concurrent studies showing that glomalin concentrations and chitinase enzyme activity both increase in soils with time following woody encroachment into grassland

  19. Spatial patterns of streambed morphology around woody debris: flume experiments and field observations on the effects of woody debris on streambed morphology

    NASA Astrophysics Data System (ADS)

    Leung, V.; Montgomery, D. R.

    2010-12-01

    The interactions between woody debris, fluid flow and sediment transport in rivers play a fundamental role in ecogeomorphology, affecting channel roughness, streambed morphology, and sediment transport and storage. In particular, woody debris increases the hydraulic and topographic complexity in rivers, leading to a greater diversity of aquatic habitats and an increase in the number of large pools that are important fish habitat and breeding grounds. In the past decade, engineered logjams have become an increasingly used tool in river management for simultaneously decreasing the rate of riverbank migration and improving aquatic habitat. Sediment deposits around woody debris build up riverbanks and counteract bank migration caused by erosion. Previous experiments of flow visualization around model woody debris suggest the amount of sediment scour and deposition are primarily related to the presence of roots and the obstructional area of the woody debris. We present the results of field surveys and sediment transport experiments of streambed morphology around stationary woody debris on a mobile bed. These experiments test the effects of root presence, root geometry and log orientation of individual stationary trees on streambed morphology. The flume contains a deformable sediment bed of medium sand, and has subcritical and turbulent flow, corresponding to flow conditions found in nature. Field surveys on the Hoh River, WA, measure the local streambed morphology around woody debris (e.g. pool and gravel-bar length, width and depth), as well as woody debris characteristics (e.g. tree diameter, tree length, root diameter and root depth). We quantified the amount of local sediment scour and deposition around woody debris of varying sizes, geometries and orientations relative to flow. We find that: 1) the presence of roots on woody debris leads to greater areas of both sediment scour and deposition; and 2) the amount of sediment scour and deposition are related to the

  20. Relationship of Course Woody Debris to Red-Cockaded Woodpecker Prey Diversity and Abundance

    SciTech Connect

    Horn, G.S.

    1999-09-03

    The abundance of diversity of prey commonly used by the red-cockaded woodpecker were monitored in experimental plots in which course woody debris was manipulated. In one treatment, all the woody debris over four inches was removed. In the second treatment, the natural amount of mortality remained intact. The overall diversity of prey was unaffected; however, wood roaches were significantly reduced by removal of woody debris. The latter suggests that intensive utilizations or harvesting practices may reduce foraging.

  1. Analysis of the pattern of potential woody cover in Texas savanna

    NASA Astrophysics Data System (ADS)

    Yang, Xuebin; Crews, Kelley A.; Yan, Bowei

    2016-10-01

    While woody plant encroachment has been observed worldwide in savannas and adversely affected the ecosystem structure and function, a thorough understanding of the nature of this phenomenon is urgently required for savanna management and restoration. Among others, potential woody cover (the maximum realizable woody cover that a given site can support), especially its variation over environment has huge implication on the encroachment management in particular, and on tree-grass interactions in general. This project was designed to explore the pattern of potential woody cover in Texas savanna, an ecosystem with a large rainfall gradient in west-east direction. Substantial random pixels were sampled across the study area from MODIS Vegetation Continuous Fields (VCF) tree cover layer (250 m). Since potential woody cover is suggested to be limited by water availability, a nonlinear 99th quantile regression was performed between the observed woody cover and mean annual precipitation (MAP) to model the pattern of potential woody cover. Research result suggests a segmented relationship between potential woody cover and MAP at MODIS scale. Potential biases as well as the practical and theoretical implications were discussed. Through this study, the hypothesis about the primary role of water availability in determining savanna woody cover was further confirmed in a relatively understudied US-located savanna.

  2. PCR-based detection of a tracheal mite of the honey bee Acarapis woodi.

    PubMed

    Kojima, Yuriko; Yoshiyama, Mikio; Kimura, Kiyoshi; Kadowaki, Tatsuhiko

    2011-10-01

    The effects of the tracheal mite Acarapis woodi on the health of honey bees have been neglected since the prevalence of Varroa mites to Apis mellifera colonies. However, tracheal mite infestation of honey bee colonies still occurs worldwide and could impose negative impact on apiculture. The detection of A. woodi requires the dissection of honey bees followed by microscopic observation of the tracheal sacs. We thus developed PCR methods to detect A. woodi. These methods facilitate rapid and sensitive detection of A. woodi in many honey bee samples for epidemiologic surveys.

  3. Importance of Coarse Woody Debris to Avian Communities in Loblolly Pine Forests

    SciTech Connect

    Lohr, S.M.; Gauthreaux, S.A.; Kilgo, J.C.

    2001-06-14

    Investigates the importance of standing and down coarse woody debris to bird communities in loblolly pine forests, researchers compared breeding and nonbreeding responses of birds among two coarse woody debris removal and control treatments. Quantification of vegetation layers to determine their effects on the experimental outcome coarse woody debris removal had no effect on the nonbreeding bird community. Most breeding and nonbreeding species used habitats with sparse midstory and well-developed understory, where as sparse canopy cover and dense midstory were important to some nonbreeding species. Snag and down coarse woody debris practices that maintain a dense understory, sparse midstory and canopy will create favorable breeding habitat.

  4. Woody encroachment over 70 years in South African savannahs: overgrazing, global change or extinction aftershock?

    PubMed

    Stevens, Nicola; Erasmus, B F N; Archibald, S; Bond, W J

    2016-09-19

    Woody encroachment in 'open' biomes like grasslands and savannahs is occurring globally. Both local and global drivers, including elevated CO2, have been implicated in these increases. The relative importance of different processes is unresolved as there are few multi-site, multi-land-use evaluations of woody plant encroachment. We measured 70 years of woody cover changes over a 1020 km(2) area covering four land uses (commercial ranching, conservation with elephants, conservation without elephants and communal rangelands) across a rainfall gradient in South African savannahs. Different directions of woody cover change would be expected for each different land use, unless a global factor is causing the increases. Woody cover change was measured between 1940 and 2010 using the aerial photo record. Detection of woody cover from each aerial photograph was automated using eCognitions' Object-based image analysis (OBIA). Woody cover doubled in all land uses across the rainfall gradient, except in conservation areas with elephants in low-rainfall savannahs. Woody cover in 2010 in low-rainfall savannahs frequently exceeded the maximum woody cover threshold predicted for African savannahs. The results indicate that a global factor, of which elevated CO2 is the likely candidate, may be driving encroachment. Elephants in low-rainfall savannahs prevent encroachment and localized megafaunal extinction is a probable additional cause of encroachment.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.

  5. Variability in the composition of short rotation woody feedstocks

    SciTech Connect

    Davis, M.F.; Johnson, D.K.; Deutch, S.

    1995-11-01

    This paper discusses the variability in chemical composition caused by clonal, geographical, and environmental effects on short rotation woody feedstocks, mainly hybrid clones of poplar. The concentrations of major and minor components have been determined by chemical analysis and pyrolysis molecular beam mass spectrometry (PY-MBMS). The chemical composition was determined for a sample set consisting of debarked wood chips from three clones of deltoides x nigra (DN) and one clone of tristis x balsamifera that were grown on four replicate plots at two locations in Wisconsin. The composition of the wood chips determined by chemical analysis and Py-MBMS showed that the tristic clone was significantly different from that of all the DN clones. The composition of the DN clones studied in this sample set were relatively similar to other hybrid poplar samples that have been analyzed over the past three years. The level of compositional variation due to clonal, geographical and environmental factors observed in short rotation woody species to date indicates that they are a consistent and stable feedstock for biofuels production. The effects of storage on different short rotation woody crops has been studied. Results of the analysis of fresh and stored hybrid poplar using traditional wet chemical analysis showed differences in the chemical composition of the feedstocks because of storage. Also presented are results from a rapid analytical technique using pyrolysis-mass spectroscopy combined with multivariate statistical analysis to assess the influence of storage on the composition of different short rotation feedstocks. Because of the rapid nature of this technique, a large number of samples could be screened to determine the extent of degradation throughout the piles. The application of this technique to the samples in this study indicated changes in chemical composition occurred during the storage period.

  6. Woody Plant Encroachment into Grasslands: Spatial Patterns of Functional Group Distribution and Community Development

    PubMed Central

    Liu, Feng; Archer, Steven R.; Gelwick, Frances; Bai, Edith; Boutton, Thomas W.; Wu, Xinyuan Ben

    2013-01-01

    Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs) better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured) were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N2-fixers (55% of species), but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA) ordination and variance partitioning (Partial CCA) indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture) and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen concentrations, the latter

  7. Groundwater uptake by woody vegetation in a semiarid oak savanna

    NASA Astrophysics Data System (ADS)

    Miller, Gretchen R.; Chen, Xingyuan; Rubin, Yoram; Ma, Siyan; Baldocchi, Dennis D.

    2010-10-01

    Groundwater can serve as an important resource for woody vegetation in semiarid landscapes, particularly when soil water is functionally depleted and unavailable to plants. This study examines the uptake of groundwater by deciduous blue oak trees (Quercus douglasii) in a California oak savanna. Here we present a suite of direct and indirect methods that demonstrate its occurrence and quantify its rates. The study site is underlain by a thin soil layer and fractured metavolcanic bedrock. Typical depth to groundwater is approximately 8 m. A variety of water storage and flux measurements were collected from 2005 to 2008, including groundwater levels, soil moisture contents, sap flows, and latent heat fluxes. During the dry season, groundwater uptake rates ranged from 4 to 25 mm month-1 and approximately 80% of total ET during June, July, and August came from groundwater. Leaf and soil water potentials supported these results, indicating that groundwater uptake was thermodynamically favorable over soil water uptake for key portions of the growing season. These findings strongly suggest that blue oaks should be considered obligate phreatophytes and that groundwater reserves provide a buffer to rapid changes in their hydroclimate, if these assets are not otherwise depleted by prolonged drought or human consumption. While groundwater uptake may provide for short-term protection, it should be viewed not as a mechanism for continued plant growth. It allows the woody vegetation to subsist during the summer but not to flourish.

  8. Expected international demand for woody and herbaceous feedstock

    SciTech Connect

    Lamers, Patrick; Jacobson, Jacob; Mohammad, Roni; Wright, Christopher

    2015-03-01

    The development of a U.S. bioenergy market and ultimately ‘bioeconomy’ has primarily been investigated with a national focus. Limited attention has been given to the potential impacts of international market developments. The goal of this project is to advance the current State of Technology of a single biorefinery to the global level providing quantitative estimates on how international markets may influence the domestic feedstock supply costs. The scope of the project is limited to feedstock that is currently available and new crops being developed to be used in a future U.S. bioeconomy including herbaceous residues (e.g., corn stover), woody biomass (e.g., pulpwood), and energy crops (e.g., switchgrass). The timeframe is set to the periods of 2022, 2030, and 2040 to align with current policy targets (e.g., the RFS2) and future updates of the Billion Ton data. This particular milestone delivers demand volumes for generic woody and herbaceous feedstocks for the main (net) importing regions along the above timeframes. The regional focus of the study is the European Union (EU), currently the largest demand region for U.S. pellets made from pulpwood and forest residues. The pellets are predominantly used in large-scale power plants (>5MWel) in the United Kingdom (UK), the Netherlands (NL), Belgium (BE), and Denmark (DK).

  9. Fire effects on tropical woody vegetation structure have been exaggerated?

    NASA Astrophysics Data System (ADS)

    Veenendaal, Elmar; Torello-Raventos, Mireia; Miranda, Heloisa; Sato, Naomi; Oliveras-Menor, Imma; Van Langevelde, Frank; Lloyd, Jon

    2015-04-01

    Since the beginning of the 20th century scientists, particularly those working in Africa, have proposed a major impact of fire frequency and intensity on woody vegetation leading to concepts such as "fire derived" savannas and "fire-mediated" feedbacks. Particularly in contact zones between forests and savannas the role of fire has been proposed as the driving agent of replacement of fire-sensitive forest-associated species with fire sensitive "fire resistant" savanna species and transition from closed forest vegetation to open savanna vegetation. In this presentation we will provide a global synthesis of the fire experiment literature with an aim to determine if general patterns can be established in terms of magnitude of fire effects on tropical vegetation structure in terms of (a) season and frequency of burning; (b) vegetation structure in the absence of fire and (c) climate. With this body of empirical data and a simple simulation model we examine if, the impact of fire on tropical woody cover as currently presented in the literature and the role of fire-mediated feedbacks in forest-savanna transitions can be justified by empirical data emanating from long term fire experiments

  10. Experimental investigation of pyrolysis process of woody biomass mixture

    NASA Astrophysics Data System (ADS)

    Kosanić, Tijana R.; Ćeranić, Mirjana B.; Đurić, Slavko N.; Grković, Vojin R.; Milotić, Milan M.; Brankov, Saša D.

    2014-06-01

    This paper describes an experimental investigation of pyrolysis of woody biomass mixture. The mixture consists of oak, beech, fir, cherry, walnut and linden wood chips with equal mass fractions. During the experiment, the sample mass inside the reactor was 10 g with a particle diameter of 5-10 mm. The sample in the reactor was heated in the temperature range of 24-650°C. Average sample heating rates in the reactor were 21, 30 and 54 °C/min. The sample mass before, during and after pyrolysis was determined using a digital scale. Experimental results of the sample mass change indicate that the highest yield of pyrolytic gas was achieved at the temperature slightly above 650°C and ranged from 77 to 85%, while char yield ranged from 15 to 23%. Heating rate has significant influence on the pyrolytic gas and char yields. It was determined that higher pyrolysis temperatures and heating rates induce higher yields of pyrolytic gas, while the char mass reduces. Condensation of pyrolytic gas at the end of the pyrolysis process at 650°C produced 2.4-2.72 g of liquid phase. The results obtained represent a starting basis for determining material and heat balance of pyrolysis process as well as woody biomass pyrolysis equipment.

  11. Origin and evolution of fleshy fruit in woody bamboos.

    PubMed

    Ruiz-Sanchez, Eduardo; Sosa, Victoria

    2015-10-01

    Several hypotheses have been suggested to explain the origin of fleshy fruit in monocots. One is that they originated in the understory of tropical regions and another is that fleshy fruit originated in tropical rainforests where high year-round rainfall implies that seasonality is not a limiting factor. Here we identify the time of origin and ecological preferences of woody bamboos to understand the evolution of the fleshy fruit known as the bacoid caryopsis. Bayesian Inference, Maximum Likelihood and molecular dating analyses were run based on eight plastid and two nuclear regions for 68 bamboo species. Climate data and soil parameters were gathered for 464 localities for these species. The ancestral type of caryopsis was reconstructed by parsimony. According to these analyses the bacoid caryopsis may have evolved independently seven times from the Late Miocene to the Early Pliocene and Mid-Pliocene to Mid-Pleistocene via convergent evolution. Our results suggest that in bamboos neither current climatic variables nor soil parameters were significantly correlated with the appearance of this type of fruit, nor do they have a phylogenetic signal. It is remarkable, however, that the first appearance of the bacoid caryopsis in bamboos might be associated with historical preferences for warmer and wetter climate during the Miocene. Further research is needed to identify whether other factors, such as vivipary or dispersal by small animals, rather than climate, could be responsible for the evolution of this trait in woody bamboos.

  12. Late-Rotation Nitrogen Management in Deciduous Short Rotation Woody Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Idle agricultural land has the potential for producing woody crops as an energy or chemical feedstock. Short rotation woody crops (SRWCs) may improve soil health, water quality, and sequester soil carbon in these intensively farmed fields. Frequently, nitrogen is the limiting nutrient in these sys...

  13. Woody encroachment in northern Great Plains grasslands: Perceptions, actions, and needs

    USGS Publications Warehouse

    Symstad, Amy; Leis, Sherry A.

    2017-01-01

    The United States Northern Great Plains (NGP) has a high potential for landscape-scale conservation, but this grassland landscape is threatened by encroachment of woody species. We surveyed NGP land managers to identify patterns in, and illustrate a broad range of, individual managers' perceptions on (1) the threat of woody encroachment to grasslands they manage, and (2) what management practices they use that may influence woody encroachment in this region. In the 34 surveys returned, which came from predominantly public lands in the study area, 79% of responses reported moderate or substantial woody encroachment. Eastern redcedar (Juniperus virginiana) and Rocky Mountain juniper (Juniperus scopulorum) were the most problematic encroachers. Thirty-one survey respondents said that prescribed fire was used on the lands they manage, and 64% of these responses reported that controlling woody encroachment was a fire management objective. However, only 18% of survey respondents using prescribed fire were achieving their desired fire return interval. Most respondents reported using mechanical and/or chemical methods to control woody species. In contrast to evidence from the central and southern Great Plains, few survey respondents viewed grazing as affecting encroachment. Although the NGP public land managers we surveyed clearly recognize woody encroachment as a problem and are taking steps to address it, many feel that the rate of their management is not keeping pace with the rate of encroachment. Developing strategies for effective woody plant control in a variety of NGP management contexts requires filling ecological science gaps and overcoming societal barriers to using prescribed fire.

  14. Non-Linear Dynamics Approach to Assessing Woody-Encroachment in Grasslands

    NASA Astrophysics Data System (ADS)

    Brunsell, N. A.; Nippert, J. B.; Van Vleck, E.

    2015-12-01

    Woody species are encroaching on grasslands globally. Here, we investigate the spatial and temporal dynamics of this encroachment in relation to climate and fire regimes in the central U.S. A low-dimensional model is used to assess stability of species composition. Sixe years of eddy covariance data at a paired grassland and woody encroachment site at the Konza Prairie LTER site are used to verify carbon and water dynamics. Historical aerial photography and remote sensing data are used to quantify the spatial diffusion of woody tree fraction into grasslands. Non-linear dynamics approaches are used to quantify the stability of vegetation and the presence of tipping points in relation to woody fraction, fire frequency and precipitation and temperature variability. Understanding the roles of multiple confounding forcing factors operating at disparate timescales is essential for predicting future woody encroachment and the water and climate implications of land cover transitions.

  15. Nutrient concentrations in coarse and fine woody debris of Populus tremuloides Michx.-dominated forests, northern Minnesota, USA

    USGS Publications Warehouse

    Klockow, Paul A.; D'Amato, Anthony W.; Bradford, John B.; Fraver, Shawn

    2014-01-01

    Contemporary forest harvesting practices, specifically harvesting woody biomass as a source of bioenergy feedstock, may remove more woody debris from a site than conventional harvesting. Woody debris, particularly smaller diameter woody debris, plays a key role in maintaining ecosystem nutrient stores following disturbance. Understanding nutrient concentrations within woody debris is necessary for assessing the long-term nutrient balance consequences of altered woody debris retention, particularly in forests slated for use as bioenergy feedstocks. Nutrient concentrations in downed woody debris of various sizes, decay classes, and species were characterized within one such forest type, Populus tremuloides Michx.-dominated forests of northern Minnesota, USA. Nutrient concentrations differed significantly between size and decay classes and generally increased as decay progressed. Fine woody debris (≤ 7.5 cm diameter) had higher nutrient concentrations than coarse woody debris (> 7.5 cm diameter) for all nutrients examined except Na and Mn, and nutrient concentrations varied among species. Concentrations of N, Mn, Al, Fe, and Zn in coarse woody debris increased between one and three orders of magnitude, while K decreased by an order of magnitude with progressing decay. The variations in nutrient concentrations observed here underscore the complexity of woody debris nutrient stores in forested ecosystems and suggest that retaining fine woody debris at harvest may provide a potentially important source of nutrients following intensive removals of bioenergy feedstocks.

  16. Non-structural carbohydrates in woody plants compared among laboratories.

    PubMed

    Quentin, Audrey G; Pinkard, Elizabeth A; Ryan, Michael G; Tissue, David T; Baggett, L Scott; Adams, Henry D; Maillard, Pascale; Marchand, Jacqueline; Landhäusser, Simon M; Lacointe, André; Gibon, Yves; Anderegg, William R L; Asao, Shinichi; Atkin, Owen K; Bonhomme, Marc; Claye, Caroline; Chow, Pak S; Clément-Vidal, Anne; Davies, Noel W; Dickman, L Turin; Dumbur, Rita; Ellsworth, David S; Falk, Kristen; Galiano, Lucía; Grünzweig, José M; Hartmann, Henrik; Hoch, Günter; Hood, Sharon; Jones, Joanna E; Koike, Takayoshi; Kuhlmann, Iris; Lloret, Francisco; Maestro, Melchor; Mansfield, Shawn D; Martínez-Vilalta, Jordi; Maucourt, Mickael; McDowell, Nathan G; Moing, Annick; Muller, Bertrand; Nebauer, Sergio G; Niinemets, Ülo; Palacio, Sara; Piper, Frida; Raveh, Eran; Richter, Andreas; Rolland, Gaëlle; Rosas, Teresa; Saint Joanis, Brigitte; Sala, Anna; Smith, Renee A; Sterck, Frank; Stinziano, Joseph R; Tobias, Mari; Unda, Faride; Watanabe, Makoto; Way, Danielle A; Weerasinghe, Lasantha K; Wild, Birgit; Wiley, Erin; Woodruff, David R

    2015-11-01

    Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g(-1) for soluble sugars, 6-533 (mean = 94) mg g(-1) for starch and 53-649 (mean = 153) mg g(-1) for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R(2) = 0.05-0.12 for soluble sugars, 0.10-0.33 for starch and 0.01-0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g(-1) for total NSC, compared with the range of laboratory estimates of 596 mg g(-1). Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41-0.91), but less so for total NSC (r = 0.45-0.84) and soluble sugars (r = 0.11-0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory

  17. Mapping Woody Plant Encroachment in Grassland Using Multiple Source Remote Sensing images: Case Study in Oklahoma

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xiao, X.; Qin, Y.; Dong, J.; Zhang, G.; Zhang, Y.; Zou, Z.; Zhou, Y.; Wu, X.; Bajgain, R.

    2015-12-01

    Woody plant encroachment (mainly Juniperus virginiana, a coniferous evergreen tree) in the native grassland has been rapidly increasing in the U.S. Southern Great Plains, largely triggered by overgrazing domestic livestock, fire suppression, and changing rainfall regimes. Increasing dense woody plants have significant implications for local grassland ecosystem dynamics, such as carbon storage, soil nutrient availability, herbaceous forage production, livestock, watershed hydrology and wildlife habitats. However, very limited data are available about the spatio-temporal dynamics of woody plant encroachment to the native grassland at regional scale. Data from remotes sensing could potentially provide relevant information and improve the conversion of native grassland to woody plant encroachment. Previous studies on woody detection in grassland mainly conducted at rangeland scale using airborne or high resolution images, which is sufficient to monitor the dynamics of woody plant encroachment in local grassland. This study examined the potential of medium resolution images to detect the woody encroachment in tallgrass prairie. We selected Cleveland county, Oklahoma, US. as case study area, where eastern area has higher woody coverage than does the western area. A 25-m Phased Array Type L-band Synthetic Aperture Radar (PALSAR, N36W98) image was used to map the trees distributed in the grassland. Then, maximum enhanced vegetation index (EVI) and normalized difference vegetation index (NDVI) in the winter calculated from time-series Landsat images was used to identify the invaded woody species (Juniperus virginiana) through phenology-based algorithm. The resulting woody plant encroachment map was compared with the results extracted from the high resolution images provided by the National Agriculture Imagery Program (NAIP). Field photos were also used to validate the accuracy. These results showed that integrating PALSAR and Landsat had good performance to identify the

  18. Woody biomass resource of Louisiana, 1991. Forest Service resource bulletin

    SciTech Connect

    Rosson, J.F.

    1993-09-01

    Data from the 1991 Louisiana forest survey were used to derive fresh and dry biomass estimates for all trees, on timberland, greater than 1.0 inch in diameter at breast height (d.b.h.). There are 470.0 million fresh tons in softwood species and 757.5 million fresh tons in hardwood species. The woody biomass resource averages 45.9 and 61.9 tons per acre for softwoods and hardwoods where they occur, respectively. Most of this biomass is in the stem portion of the trees--85 percent for softwoods and 75 percent for hardwoods. Nonindustrial private landowners hold 58 and 69 percent of the total softwood and hardwood biomass resource, respectively.

  19. Woody biomass size reduction with selective material orientation

    SciTech Connect

    Dooley, James H.; Lanning, David N.; Lanning, Christopher J.

    2013-01-01

    Roundwood logs from forests and energy plantations must be chipped, ground, or otherwise comminuted into small particles prior to conversion to solid or liquid biofuels. Rotary veneer followed by cross-grain shearing is demonstrated to be a novel and low energy consuming method for primary breakdown of logs into a raw material having high transport and storage density. Processing of high moisture raw logs into 2.5 – 4.2 mm particles prior to drying or conversion consumes less than 20% of the energy required for achieving similar particle size with hammer mills while producing a more uniform particle shape and size. As a result, energy savings from the proposed method may reduce the comminution cost of woody feedstocks by more than half.

  20. Woody biomass size reduction with selective material orientation

    DOE PAGES

    Dooley, James H.; Lanning, David N.; Lanning, Christopher J.

    2013-01-01

    Roundwood logs from forests and energy plantations must be chipped, ground, or otherwise comminuted into small particles prior to conversion to solid or liquid biofuels. Rotary veneer followed by cross-grain shearing is demonstrated to be a novel and low energy consuming method for primary breakdown of logs into a raw material having high transport and storage density. Processing of high moisture raw logs into 2.5 – 4.2 mm particles prior to drying or conversion consumes less than 20% of the energy required for achieving similar particle size with hammer mills while producing a more uniform particle shape and size. Asmore » a result, energy savings from the proposed method may reduce the comminution cost of woody feedstocks by more than half.« less

  1. Patterns of woody plant invasion in an Argentinean coastal grassland

    NASA Astrophysics Data System (ADS)

    Alberio, Constanza; Comparatore, Viviana

    2014-01-01

    Coastal dune grasslands are fragile ecosystems that have historically been subjected to various types of uses and human activities. In Buenos Aires Province (Argentina), these areas are frequently afforested for urban and touristic development. The introduction and subsequent spread of exotic tree species is one of the main threats to conservation of natural grasslands as invasive trees strongly transform their structure and composition. The aim of this study was to identify patterns of woody plant invasion comparing plant communities and environmental variables between invaded and non-invaded areas surrounding the coastal village of Mar Azul, Argentina. Coastal grasslands in this area are being invaded by Populus alba (white poplar) and Acacia longifolia (coast wattle). The height of the saplings and the richness of the accompanying vegetation were evaluated in relation to the distance from the edge of the mature tree patches. Also, the cover, richness and diversity of all species in the invaded and non-invaded areas were measured, as well as soil pH, temperature and particle size. Negative correlations were found between the height of the saplings and distance to mature tree patches in all areas. The richness of the accompanying vegetation was negatively and positively correlated with the distance from the poplar and acacia area, respectively. The most abundant native species was Cortaderia selloana. Less cover, richness and diversity of native plant species and greater soil particle size were found in invaded areas, where the proportion of bare soil was higher. Also, a higher proportion of leaf litter in the invaded areas was registered. The results emphasize the invasive capacity of P. alba and A. longifolia advancing on the native communities and reducing their richness. Knowledge of the impact of invasive woody plants in coastal grasslands is important to design active management strategies for conservation purposes.

  2. BAAD: a Biomass And Allometry Database for woody plants

    SciTech Connect

    Falster, Daniel; Duursma, Remko; Ishihara, Masae; Barneche, Diego; Fitzjohn, Richard; Varhammar, Angelica; Aiba, Masahiro; Ando, M.; Anten, Niels; Aspinwall, Michael J.; Baltzer, Jennifer; Baraloto, Christopher; Battaglia, Michael; Battles, John; Bond-Lamberty, Benjamin; van Breugel, Michiel; Camac, James; Claveau, Yves; Coll Mir, Llus; Dannoura, Dannoura; Delagrange, Sylvain; Domec, Jean-Cristophe; Fatemi, Farrah; Feng, Wang; Gargaglione, Veronica; Goto, Yoshiaki; Hagihara, Akio; Hall, Jefferson S.; Hamilton, Steve; Harja, Degi; Hiura, Tsutom; Holdaway, Robert; Hutley, L. B.; Ichie, Tomoaki; Jokela, Eric; Kantola, Anu; Kelly, Jeffery W.; Kenzo, Tanaka; King, David A.; Kloeppel, Brian; Kohyama, Takashi; Komiyama, Akira; Laclau, Jean-Paul; Lusk, Christopher; Maguire, Doug; le Maire, Guerric; Makela, Annikki; Markesteijn, Lars; Marshall, John; McCulloh, Kate; Miyata, Itsuo; Mokany, Karen; Mori, Shigeta; Myster, Randall; Nagano, Masahiro; Naidu, Shawna; Nouvellon, Yann; O'Grady, Anthony; O'Hara, Kevin; Ohtsuka, Toshiyuki; Osada, Noriyuki; Osunkoya, Olusegun O.; Luis Peri, Pablo; Petritan, Mary; Poorter, Lourens; Portsmuth, Angelika; Potvin, Catherine; Ransijn, Johannes; Reid, Douglas; Ribeiro, Sabina C.; Roberts, Scott; Rodriguez, Rolando; Saldana-Acosta, Angela; Santa-Regina, Ignacio; Sasa, Kaichiro; Gailia Selaya, Nadezhda; Sillett, Stephen; Sterck, Frank; Takagi, Kentaro; Tange, Takeshi; Tanouchi, Hiroyuki; Tissue, David; Umehara, Tohru; Utsugi, Hajime; Vadeboncoeur, Matthew; Valladares, Fernando; Vanninen, Petteri; Wang, Jian; Wenk, Elizabeth; Williams, Dick; Ximenes, Fabiano de Aquino; Yamaba, Atsushi; Yamada, Toshihiro; Yamakura, Takuo; Yanai, Ruth; York, Robert

    2015-05-07

    Quantifying the amount of mass or energy invested in plant tissues is of fundamental interest across a range of disciplines, including ecology, forestry, ecosystem science, and climate change science (Niklas, 1994; Chave et al. 2005; Falster et al. 2011). The allocation of net primary production into different plant components is an important process affecting the lifetime of carbon in ecosystems, and resource use and productivity by plants (Cannell & Dewar, 1994; Litton et al. 2007; Poorter et al. 2012). While many studies in have destructively harvested woody plants in the name of science, most of these data have only been made available in the form of summary tables or figures included in publications. Until now, the raw data has resided piecemeal on the hard drives of individual scientists spread around the world. Several studies have gathered together the fitted (allometric) equations for separate datasets (Ter-Mikaelian & Korzukhin, 1997; Jenkins et al. 2003; Zianis et al. 2005; Henry et al. 2013), but none have previously attempted to organize and share the raw individual plant data underpinning these equations on a large scale. Gathered together, such data would represent an important resource for the community, meeting a widely recognised need for rich, open data resources to solve ecological problems (Costello et al. 2013; Fady et al. 2014; Harfoot & Roberts, 2014; Costello et al. 2013). We (D.S. Falster and R.A. Duursma, with the help of D.R. Barneche, R.G. FitzJohn and A. Vårhammar) set out to create such a resource, by asking authors directly whether they would be willing to make their raw data files freely available. The response was overwhelming: nearly everyone we contacted was interested to contribute their raw data. Moreover, we were invited to incorporate another compilation led by M. Ishihara and focussing on Japanese literature. As a result, we present BAAD: a Biomass And Allometry Database for woody plants, comprising data collected in 174

  3. Does stream flow structure woody riparian vegetation in subtropical catchments?

    PubMed

    James, Cassandra S; Mackay, Stephen J; Arthington, Angela H; Capon, Samantha J; Barnes, Anna; Pearson, Ben

    2016-08-01

    The primary objective of this study was to test the relevance of hydrological classification and class differences to the characteristics of woody riparian vegetation in a subtropical landscape in Queensland, Australia. We followed classification procedures of the environmental flow framework ELOHA - Ecological Limits of Hydrologic Alteration. Riparian surveys at 44 sites distributed across five flow classes recorded 191 woody riparian species and 15, 500 individuals. There were differences among flow classes for riparian species richness, total abundance, and abundance of regenerating native trees and shrubs. There were also significant class differences in the occurrence of three common tree species, and 21 indicator species (mostly native taxa) further distinguished the vegetation characteristics of each flow class. We investigated the influence of key drivers of riparian vegetation structure (climate, depth to water table, stream-specific power, substrate type, degree of hydrologic alteration, and land use) on riparian vegetation. Patterns were explained largely by climate, particularly annual rainfall and temperature. Strong covarying drivers (hydrology and climate) prevented us from isolating the independent influences of these drivers on riparian assemblage structure. The prevalence of species considered typically rheophytic in some flow classes implies a more substantial role for flow in these classes but needs further testing. No relationships were found between land use and riparian vegetation composition and structure. This study demonstrates the relevance of flow classification to the structure of riparian vegetation in a subtropical landscape, and the influence of covarying drivers on riparian patterns. Management of environmental flows to influence riparian vegetation assemblages would likely have most potential in sites dominated by rheophytic species where hydrological influences override other controls. In contrast, where vegetation assemblages are

  4. Phytoliths in woody plants from the Miombo woodlands of Mozambique

    PubMed Central

    Mercader, Julio; Bennett, Tim; Esselmont, Chris; Simpson, Steven; Walde, Dale

    2009-01-01

    Background and Aims There are no descriptions of phytoliths produced by plants from the ‘Zambezian’ zone, where Miombo woodlands are the dominant element of the largest single phytochorion in sub-Saharan Africa. The preservation of phytoliths in fossil records of Africa makes phytoliths a tool to study early plant communities. Paleo-ethnobotanical interpretation of phytoliths relies on the comparison of ancient types with morphotypes extracted from living reference collections. Methods Phytoliths were extracted from plant samples representing 41 families, 77 genera and 90 species through sonic cleaning, dry ashing and acid treatment; and phytoliths thus extracted were quantified. For each species, an average of 216 phytoliths were counted. The percentage of each morphotype identified per species was calculated, and types were described according to the descriptors from the International Code for Phytolith Nomenclature. Phytolith assemblages were subject to discriminant analysis, cluster analysis and principal component analysis. Key Results Phytoliths were grouped into 57 morphotypes (two were articulated forms and 55 were discrete shapes), and provide a reference collection of phytolith assemblages produced by Miombo woody species. Common and unique morphotypes are described and taxonomic and grouping variables are looked into from a statistical perspective. Conclusions The first quantitative taxonomy of phytoliths from Miombos is presented here, including new types and constituting the most extensive phytolith key for any African ecoregion. Evidence is presented that local woody species are hypervariable silica producers and their phytolith morphotypes are highly polymorphic. The taxonomic significance of these phytoliths is largely poor, but there are important exceptions that include the morphotypes produced by members from >10 families and orders. The typical phytolithic signal that would allow scientists to identify ancient woodlands of

  5. Effect of downed woody debris on small mammal anti-predator behavior.

    SciTech Connect

    Hinkleman, Travis, M.; Orrock, John, L.; Loeb, Susan, C.

    2011-10-01

    Anti-predator behavior can affect prey growth, reproduction, survival, and generate emergent effects in food webs. Small mammals often lower the cost of predation by altering their behavior in response to shrubs,but the importance of other microhabitat features, such as downed woody debris, for anti-predator behavior is unknown. We used givingup densities to quantify the degree to which downed woody debris alters perceived predation risk by small mammals in southeastern pineforests. We placed 14 foraging trays next to large downed woody debris,shrubs, and in open areas for 12 consecutive nights. Moon illumination, a common indicator of predation risk, led to a similar reduction in small mammal foraging in all three microhabitats (open, downed woody debris,and shrub). Small mammals perceived open microhabitats as riskier than shrub microhabitats, with downed woody debris habitats perceived as being of intermediate risk between shrub and open microhabitats. Despite the presumed benefits of the protective cover of downed woody debris, small mammals may perceive downed woody debris as a relatively risky foraging site in southeastern pine forests where the high diversity and abundance of rodent-eating snakes may provide a primary predatory threat.

  6. Fire and grazing influences on rates of riparian woody plant expansion along grassland streams.

    PubMed

    Veach, Allison M; Dodds, Walter K; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1-2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1-2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency.

  7. The affect of a clearcut environment on woody debris respiration rate dynamics, Harvard Forest, Massachusetts

    NASA Astrophysics Data System (ADS)

    Vanderhoof, M. K.; Williams, C. L.

    2011-12-01

    At an ecosystem scale, the distribution of carbon is largely a function of stand development and disturbance processes. Clearcut logging remains a common practice both in the United States and globally and typically results in elevated storage of carbon in onsite woody debris and detritus. The residence time and decomposition rate of this woody debris and detritus will affect the rate of CO2 efflux to the atmosphere and thus affect the long term consequences of such disturbances on carbon flux and storage. The removal of a forest canopy also affects a site's microclimate including the albedo, air temperature, air humidity, as well as soil temperature and moisture, many of the same factors that affect the rate of woody debris decomposition. Thus it could be expected that differences in woody debris characteristics (e.g. size, abundance, state of decay), as well as differences in microclimate, between mature and recently clearcut forest sites, would result in differences in piece and site-level woody debris decomposition rates. Although woody debris stocks post-harvest have been well characterized, few studies have explored post-disturbance woody debris respiration rates, which directly measures carbon emissions from woody debris, distinguishing decomposition from mass loss due to fragmentation or leaching. This study addressed the question: does a clearcut environment in a temperate forest affect the rate of decomposition of coarse woody debris? The rate of respiration of downed spruce logs were repeatedly measured in-situ using an LI-6250 gas analyzer in Harvard Forest, Petersham, Massachusetts. Treatments included clear-cut, shaded clear-cut, mature spruce stand, and transfer (from clearcut to spruce stand). Gas analyzer measurements were accompanied by measurements of log temperature and percent water, soil temperature, moisture and pH, as well as light levels, air temperature and humidity to determine dominant drivers of respiration rates.

  8. Fire and Grazing Influences on Rates of Riparian Woody Plant Expansion along Grassland Streams

    PubMed Central

    Veach, Allison M.; Dodds, Walter K.; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1–2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1–2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency. PMID:25192194

  9. Boron deficiency in woody plants: various responses and tolerance mechanisms

    PubMed Central

    Wang, Nannan; Yang, Chengquan; Pan, Zhiyong; Liu, Yongzhong; Peng, Shu’ang

    2015-01-01

    Boron (B) is an essential microelement for higher plants, and its deficiency is widespread around the world and constrains the productivity of both agriculture and forestry. In the last two decades, numerous studies on model or herbaceous plants have contributed greatly to our understanding of the complex network of B-deficiency responses and mechanisms for tolerance. In woody plants, however, fewer studies have been conducted and they have not well been recently synthesized or related to the findings on model species on B transporters. Trees have a larger body size, longer lifespan and more B reserves than do herbaceous plants, indicating that woody species might undergo long-term or mild B deficiency more commonly and that regulation of B reserves helps trees cope with B deficiency. In addition, the highly heterozygous genetic background of tree species suggests that they may have more complex mechanisms of response and tolerance to B deficiency than do model plants. Boron-deficient trees usually exhibit two key visible symptoms: depression of growing points (root tip, bud, flower, and young leaf) and deformity of organs (root, shoot, leaf, and fruit). These symptoms may be ascribed to B functioning in the cell wall and membrane, and particularly to damage to vascular tissues and the suppression of both B and water transport. Boron deficiency also affects metabolic processes such as decreased leaf photosynthesis, and increased lignin and phenol content in trees. These negative effects will influence the quality and quantity of wood, fruit and other agricultural products. Boron efficiency probably originates from a combined effect of three processes: B uptake, B translocation and retranslocation, and B utilization. Root morphology and mycorrhiza can affect the B uptake efficiency of trees. During B translocation from the root to shoot, differences in B concentration between root cell sap and xylem exudate, as well as water use efficiency, may play key roles in

  10. Woody pretzels: spirocycles from vetiver to patchouli and Georgywood.

    PubMed

    Kraft, Philip

    2008-06-01

    This review, including new experimental results, is the summary of a talk at the RSC/SCI conference 'flavours & fragrances 2007' in London, Imperial College, 24-26 September, 2007. Though the third dimension of the receptor models of J. E. Amoore rarely was exceeding 4 A, the world of woody odorants such as (+)-cedrol (3; cedarwood), (-)-khusimone (4; vetiver), and (-)-patchoulol (5; patchouli) is anything but flat. Any tricyclic skeleton with a zero-bridge contains a spirocyclic ring system determining its 3D structure, so spirocycles (spira, Lat. pretzel) are the fastest access to the third dimension. In the vetiver family, a spirocyclic mimic 9 of (-)-khusimone (4) was first discovered by chance by Büchi in 1976, and also by chance, we obtained another system, 12, with a characteristic vetiver smell by tandem-Rupe-Nazarov reaction of alkyne diols. A 5-A distance between a quaternary C-atom and a carbonyl group (or alternative HB acceptor) with an alpha-methyl or methylene branching is proposed to be the key to their vetiver odor. Upon scale-up of one of these odorants, 24, we discovered a very powerful (0.067 ng/l) impurity with a most typical patchouli scent: the spirocyclic, sterically crowded hydroxy ketone 33--a most unusual structure for a patchouli odorant. Several spirocyclic hydroxy ketone analogs, also with inverted ring systems such as in 70 and 84, provided new insights into the structure-odor correlation of this family. A superposition analysis indicated the carbonyl function of the hydroxy ketone to overlay on the geminal dimethyl motive of (-)-patchoulol. And indeed, the corresponding hydroxy ketone of patchoulol, 59, synthesized in 13 steps from Cyclal C (63), also emanated a patchouli odor. Finally, the synthesis and olfactory properties of twelve rigid spirocyclic analogs, 95-97, 99-102, and 106-110, of Georgywood (91) are presented that highlight stereochemical requirements for woody odorants and raise doubts about an alpha-helical binding

  11. Woody encroachment reduces nutrient limitation and promotes soil carbon sequestration

    PubMed Central

    Blaser, Wilma J; Shanungu, Griffin K; Edwards, Peter J; Olde Venterink, Harry

    2014-01-01

    During the past century, the biomass of woody species has increased in many grassland and savanna ecosystems. As many of these species fix nitrogen symbiotically, they may alter not only soil nitrogen (N) conditions but also those of phosphorus (P). We studied the N-fixing shrub Dichrostachys cinerea in a mesic savanna in Zambia, quantifying its effects upon pools of soil N, P, and carbon (C), and availabilities of N and P. We also evaluated whether these effects induced feedbacks upon the growth of understory vegetation and encroaching shrubs. Dichrostachys cinerea shrubs increased total N and P pools, as well as resin-adsorbed N and soil extractable P in the top 10-cm soil. Shrubs and understory grasses differed in their foliar N and P concentrations along gradients of increasing encroachment, suggesting that they obtained these nutrients in different ways. Thus, grasses probably obtained them mainly from the surface upper soil layers, whereas the shrubs may acquire N through symbiotic fixation and probably obtain some of their P from deeper soil layers. The storage of soil C increased significantly under D. cinerea and was apparently not limited by shortages of either N or P. We conclude that the shrub D. cinerea does not create a negative feedback loop by inducing P-limiting conditions, probably because it can obtain P from deeper soil layers. Furthermore, C sequestration is not limited by a shortage of N, so that mesic savanna encroached by this species could represent a C sink for several decades. We studied the effects of woody encroachment on soil N, P, and C pools, and availabilities of N and P to Dichrostachys cinerea shrubs and to the understory vegetation. Both N and P pools in the soil increased along gradients of shrub age and cover, suggesting that N fixation by D. cinerea did not reduce the P supply. This in turn suggests that continued growth and carbon sequestration in this mesic savanna ecosystems are unlikely to be constrained by nutrient

  12. Pretreatment of woody biomass for biofuel production: energy efficiency, technologies, and recalcitrance.

    PubMed

    Zhu, J Y; Pan, Xuejun; Zalesny, Ronald S

    2010-07-01

    This mini review discusses several key technical issues associated with cellulosic ethanol production from woody biomass: energy consumption for woody biomass pretreatment, pretreatment energy efficiency, woody biomass pretreatment technologies, and quantification of woody biomass recalcitrance. Both total sugar yield and pretreatment energy efficiency, defined as the total sugar recovery divided by total energy consumption for pretreatment, should be used to evaluate the performance of a pretreatment process. A post-chemical pretreatment wood size-reduction approach was proposed to significantly reduce energy consumption. The review also emphasizes using a low liquid-to-wood ratio (L/W) to reduce thermal energy consumption for any thermochemical/physical pretreatment in addition to reducing pretreatment temperature.

  13. Woody cover and hominin environments in the past 6million years

    NASA Astrophysics Data System (ADS)

    Cerling, Thure E.; Wynn, Jonathan G.; Andanje, Samuel A.; Bird, Michael I.; Korir, David Kimutai; Levin, Naomi E.; Mace, William; Macharia, Anthony N.; Quade, Jay; Remien, Christopher H.

    2011-08-01

    The role of African savannahs in the evolution of early hominins has been debated for nearly a century. Resolution of this issue has been hindered by difficulty in quantifying the fraction of woody cover in the fossil record. Here we show that the fraction of woody cover in tropical ecosystems can be quantified using stable carbon isotopes in soils. Furthermore, we use fossil soils from hominin sites in the Awash and Omo-Turkana basins in eastern Africa to reconstruct the fraction of woody cover since the Late Miocene epoch (about 7 million years ago). 13C/12C ratio data from 1,300 palaeosols at or adjacent to hominin sites dating to at least 6million years ago show that woody cover was predominantly less than ~40% at most sites. These data point to the prevalence of open environments at the majority of hominin fossil sites in eastern Africa over the past 6million years.

  14. Woody Plant Cover Dynamics in Sahelian Drylands from Earth Observation Based Seasonal Metrics

    NASA Astrophysics Data System (ADS)

    Brandt, M.; Hiernaux, P.; Fensholt, R.; Tagesson, T.; Rasmussen, K.; Mbow, C.

    2015-12-01

    Woody plants play an important role in drylands primary productivity and peoples' livelihood, however, due to their scattered appearance, quantifying and monitoring their abundance over a large area is challenging. From in situ measured woody cover we develop a phenology driven model to estimate the canopy cover of woody species in the Sahelian drylands. Annual maps are applied to monitor dynamics of woody populations in relation to climate and anthropogenic interference. The model estimates the total canopy cover of all woody phanerophytes and the concept is based on the significant difference in phenophases of dryland trees, shrubs and bushes as compared to that of the herbaceous plants. Whereas annual herbaceous are only green during the rainy season and senescence occurs shortly after flowering towards the last rains, most woody plants remain photosynthetically active over large parts of the year. We use Moderate Resolution Imaging Spectroradiometer (MODIS) and SPOT VEGETATION (VGT) seasonal metrics representing the dry season to reproduce in situ woody cover at 77 field sites (178 observations in 3x3 km plots between 2000 and 2014) in Niger, Mali and Senegal. The extrapolation to Sahel scale shows agreement between VGT and MODIS at an almost nine times higher woody cover than in the global tree cover product MOD44B which only captures trees of a certain minimum size. Trends over 15 years show that the pattern is closely related to population density and land cover/use. A negative woody cover change can be observed in densely populated areas, but a positive change is seen in sparsely populated regions. Whereas woody cover in cropland is generally stable, it is strongly positive in savannas and woodland. Discrepancies between the countries are huge and also deforestation can be observed at a more local scale. The method is applicable and derived woody cover maps of the Sahel are freely available. They represent an improvement of existing products and a

  15. Ecohydrological Impacts of Woody Phreatophyte Invasion Within a Semiarid Riparian Environment

    NASA Astrophysics Data System (ADS)

    Scott, R. L.; Huxman, T. E.; Williams, D. G.; Goodrich, D. C.

    2005-12-01

    Along the Upper San Pedro River in southeastern Arizona deep-rooted woody phreatophytes such as the non-native Tamarix ramosissima (salt cedar) and the native Prosopis velutina (velvet mesquite) are expanding their range, but we have little understanding about how this change in vegetation composition will change the cycling of water and nutrients in these riparian ecosystems. We compared water and carbon dioxide fluxes over a grassland, a grassland-shrubland mosaic, and a fully developed woodland to evaluate potential consequences of woody plant encroachment on important ecosystem processes. Using fluxes measured by eddy covariance in 2003 we found that ecosystem evapotranspiration (ET) and net ecosystem exchange of carbon dioxide (NEE) increased with woody plant encroachment. The dominant grass or shrub at all sites accessed groundwater to some degree, but groundwater use increased with woody plant density. Greater access to groundwater for the deeper-rooted woody plants apparently decouples ecosystem evapotranspiration from gross ecosystem production (GEP) with respect to precipitation. The woody plants were better able to use the stable groundwater source, which increased net carbon dioxide gain during the dry periods by maintaining plant function. However, this enhanced plant activity leads to substantial accumulation of leaf litter on the soil surface that, during rainy periods, may lead to high microbial respiration rates that offset these photosynthetic fluxes. These initial data suggest that the ability of the woody plants to better exploit water resources in riparian areas results in enhanced carbon sequestration at the expense of increased groundwater use under current climate conditions, but the potential does not scale specifically as a function of woody plant density.

  16. Trade-offs between savanna woody plant diversity and carbon storage in the Brazilian Cerrado.

    PubMed

    Pellegrini, Adam F A; Socolar, Jacob B; Elsen, Paul R; Giam, Xingli

    2016-10-01

    Incentivizing carbon storage can be a win-win pathway to conserving biodiversity and mitigating climate change. In savannas, however, the situation is more complex. Promoting carbon storage through woody encroachment may reduce plant diversity of savanna endemics, even as the diversity of encroaching forest species increases. This trade-off has important implications for the management of biodiversity and carbon in savanna habitats, but has rarely been evaluated empirically. We quantified the nature of carbon-diversity relationships in the Brazilian Cerrado by analyzing how woody plant species richness changed with carbon storage in 206 sites across the 2.2 million km(2) region at two spatial scales. We show that total woody plant species diversity increases with carbon storage, as expected, but that the richness of endemic savanna woody plant species declines with carbon storage both at the local scale, as woody biomass accumulates within plots, and at the landscape scale, as forest replaces savanna. The sharpest trade-offs between carbon storage and savanna diversity occurred at the early stages of carbon accumulation at the local scale but the final stages of forest encroachment at the landscape scale. Furthermore, the loss of savanna species quickens in the final stages of forest encroachment, and beyond a point, savanna species losses outpace forest species gains with increasing carbon accumulation. Our results suggest that although woody encroachment in savanna ecosystems may provide substantial carbon benefits, it comes at the rapidly accruing cost of woody plant species adapted to the open savanna environment. Moreover, the dependence of carbon-diversity trade-offs on the amount of savanna area remaining requires land managers to carefully consider local conditions. Widespread woody encroachment in both Australian and African savannas and grasslands may present similar threats to biodiversity.

  17. Mapping gains and losses in woody vegetation across global tropical drylands.

    PubMed

    Tian, Feng; Brandt, Martin; Liu, Yi Y; Rasmussen, Kjeld; Fensholt, Rasmus

    2017-04-01

    Woody vegetation in global tropical drylands is of significant importance for both the interannual variability of the carbon cycle and local livelihoods. Satellite observations over the past decades provide a unique way to assess the vegetation long-term dynamics across biomes worldwide. Yet, the actual changes in the woody vegetation are always hidden by interannual fluctuations of the leaf density, because the most widely used remote sensing data are primarily related to the photosynthetically active vegetation components. Here, we quantify the temporal trends of the nonphotosynthetic woody components (i.e., stems and branches) in global tropical drylands during 2000-2012 using the vegetation optical depth (VOD), retrieved from passive microwave observations. This is achieved by a novel method focusing on the dry season period to minimize the influence of herbaceous vegetation and using MODerate resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data to remove the interannual fluctuations of the woody leaf component. We revealed significant trends (P < 0.05) in the woody component (VODwood ) in 35% of the areas characterized by a nonsignificant trend in the leaf component (VODleaf modeled from NDVI), indicating pronounced gradual growth/decline in woody vegetation not captured by traditional assessments. The method is validated using a unique record of ground measurements from the semiarid Sahel and shows a strong agreement between changes in VODwood and changes in ground observed woody cover (r(2)  = 0.78). Reliability of the obtained woody component trends is also supported by a review of relevant literatures for eight hot spot regions of change. The proposed approach is expected to contribute to an improved assessment of, for example, changes in dryland carbon pools.

  18. Plant diversity and ecosystem multifunctionality peak at intermediate levels of woody cover in global drylands

    PubMed Central

    Soliveres, Santiago; Maestre, Fernando T.; Eldridge, David J.; Delgado-Baquerizo, Manuel; Quero, José Luis; Bowker, Matthew A.; Gallardo, Antonio

    2015-01-01

    Aim The global spread of woody plants into grasslands is predicted to increase over the coming century. While there is general agreement regarding the anthropogenic causes of this phenomenon, its ecological consequences are less certain. We analyzed how woody vegetation of differing cover affects plant diversity (richness and evenness) and multiple ecosystem functions (multifunctionality) in global drylands, and how this changes with aridity. Location 224 dryland sites from all continents except Antarctica widely differing in their environmental conditions (from arid to dry-subhumid sites) and woody covers (from 0 to 100%). Methods Using a standardized field survey, we measured the cover, richness and evenness of perennial vegetation. At each site, we measured 14 ecosystem functions related to soil fertility and the build-up of nutrient pools. These functions are critical for maintaining ecosystem function in drylands. Results Species richness and ecosystem multifunctionality were strongly influenced by woody vegetation, with both variables peaking at relative woody covers (RWC) of 41-60%. This relationship shifted with aridity. We observed linear positive effects of RWC in dry-subhumid sites. These positive trends shifted to hump-shaped RWC-diversity and multifunctionality relationships under semiarid environments. Finally, hump-shaped (richness, evenness) or linear negative (multifunctionality) effects of RWC were found under the most arid conditions. Main conclusions Plant diversity and multifunctionality peaked at intermediate levels of woody cover, although this relationship became increasingly positive under wetter environments. This comprehensive study accounts for multiple ecosystem attributes across a range of woody covers and environmental conditions. Our results help us to reconcile contrasting views of woody encroachment found in current literature and can be used to improve predictions of the likely effects of encroachment on biodiversity and ecosystem

  19. The role of short-rotation woody crops in sustainable development

    SciTech Connect

    Shepard, J.P.; Tolbert, V.R.

    1996-12-31

    One answer to increase wood production is by increasing management intensity on existing timberland, especially in plantation forests. Another is to convert land currently in agriculture to timberland. Short-rotation woody crops can be used in both cases. But, what are the environmental consequences? Short-rotation woody crops can provide a net improvement in environmental quality at both local and global scales. Conversion of agricultural land to short-rotation woody crops can provide the most environmental quality enhancement by reducing erosion, improving soil quality, decreasing runoff, improving groundwater quality, and providing better wildlife habitat. Forest products companies can use increased production from intensively managed short-rotation woody crop systems to offset decreased yield from the portion of their timberland that is managed less intensively, e.g. streamside management zones and other ecologically sensitive or unique areas. At the global scale, use of short-rotation woody crops for bioenergy is part of the solution to reduce greenhouse gases produced by burning fossil fuels. Incorporating short-rotation woody crops into the agricultural landscape also increases storage of carbon in the soil, thus reducing atmospheric concentrations. In addition, use of wood instead of alternatives such as steel, concrete, and plastics generally consumes less energy and produces less greenhouse gases. Cooperative research can be used to achieve energy, fiber, and environmental goals. This paper will highlight several examples of ongoing cooperative research projects that seek to enhance the environmental aspects of short-rotation woody crop systems. Government, industry, and academia are conducting research to study soil quality, use of mill residuals, nutrients in runoff and groundwater, and wildlife use of short-rotation woody crop systems in order to assure the role of short-rotation crops as a sustainable way of meeting society`s needs.

  20. Utilization characteristics and importance of woody biomass resources on the rural-urban fringe in botswana.

    PubMed

    Nkambwe, Musisi; Sekhwela, Mogodisheng B M

    2006-02-01

    This article examines the utilization characteristics and importance of woody biomass resources in the rural-urban fringe zones of Botswana. In the literature for Africa, attention has been given to the availability and utilization of biomass in either urban or rural environments, but the rural-urban fringe has been neglected. Within southern Africa, this neglect is not justified; the rural-urban fringe, not getting the full benefits available in urban environments in Botswana, has developed problems in woody biomass availability and utilization that require close attention. In this article, socioeconomic data on the importance of woody biomass in the Batlokwa Tribal Territory, on the rural-urban fringe of Gaborone, Botswana, were collected together with ecologic data that reveal the utilization characteristics and potential for regrowth of woody biomass. The analysis of these results show that local woody biomass is very important in the daily lives of communities in the rural-urban fringe zones and that there is a high level of harvesting. However, there is no effort in planning land use in the tribal territory to either conserve this resource or provide alternatives to its utilization. The future of woody biomass resources in Botswana's rural-urban fringe is uncertain. The investigators recommend that a comprehensive policy for the development of the rural-urban fringe consider the importance of this resource. The neglect of this resource will have far-reaching implications on the livelihoods of residents as well as the environment in this zone.

  1. Woody debris in north Iberian streams: influence of geomorphology, vegetation, and management.

    PubMed

    Diez, J R; Elosegi, A; Pozo, J

    2001-11-01

    The effect of stream geomorphology, maturity, and management of riparian forests on abundance, role, and mobility of wood was evaluated in 20 contrasting reaches in the Agüera stream catchment (northern Iberian Peninsula). During 1 year the volume of woody debris exceeding 1 cm in diameter was measured in all reaches. All large woody debris (phi > 5 cm) pieces were tagged, their positions mapped, and their subsequent changes noted. Volume of woody debris was in general low and ranged from 40 to 22,000 cm3 m-2; the abundance of debris dams ranged from 0 to 5.5 per 100 m of channel. Wood was especially rare and unstable in downstream reaches, or under harvested forests (both natural or plantations). Results stress that woody debris in north Iberian streams has been severely reduced by forestry and log removal. Because of the important influence of woody debris on structure and function of stream systems, this reduction has likely impacted stream communities. Therefore, efforts to restore north Iberian streams should include in-channel and riparian management practices that promote greater abundance and stability of large woody debris whenever possible.

  2. Woody plant encroachment of grasslands: a comparison of terrestrial and wetland settings.

    PubMed

    Saintilan, Neil; Rogers, Kerrylee

    2015-02-01

    A global trend of woody plant encroachment of terrestrial grasslands is co-incident with woody plant encroachment of wetland in freshwater and saline intertidal settings. There are several arguments for considering tree encroachment of wetlands in the context of woody shrub encroachment of grassland biomes. In both cases, delimitation of woody shrubs at regional scales is set by temperature thresholds for poleward extent, and by aridity within temperature limits. Latitudinal expansion has been observed for terrestrial woody shrubs and mangroves, following recent warming, but most expansion and thickening has been due to the occupation of previously water-limited grassland/saltmarsh environments. Increases in atmospheric CO₂, may facilitate the recruitment of trees in terrestrial and wetland settings. Improved water relations, a mechanism that would predict higher soil moisture in grasslands and saltmarshes, and also an enhanced capacity to survive arid conditions, reinforces local mechanisms of change. The expansion of woody shrubs and mangroves provides a negative feedback on elevated atmospheric CO₂ by increasing carbon sequestration in grassland and saltmarsh, and is a significant carbon sink globally. These broad-scale vegetation shifts may represent a new stable state, reinforced by positive feedbacks between global change drivers and endogenic mechanisms of persistence in the landscape.

  3. Woody riparian vegetation response to different alluvial water table regimes

    USGS Publications Warehouse

    Shafroth, P.B.; Stromberg, J.C.; Patten, D.T.

    2000-01-01

    Woody riparian vegetation in western North American riparian ecosystems is commonly dependent on alluvial groundwater. Various natural and anthropogenic mechanisms can cause groundwater declines that stress riparian vegetation, but little quantitative information exists on the nature of plant response to different magnitudes, rates, and durations of groundwater decline. We observed groundwater dynamics and the response of Populus Fremontii, Salix gooddingii, and Tamarix ramosissima saplings at 3 sites between 1995 and 1997 along the Bill Williams River, Arizona. At a site where the lowest observed groundwater level in 1996 (-1.97 m) was 1.11 m lower than in 1995 (-0.86 m), 92-100% of Populus and Salix saplings died, whereas 0-13% of the Tamarix stems died. A site with greater absolute water table depths in 1996 (-2.55 m), but less change from the 1995 condition (0.55 m), showed less Populus and Salix mortality and increased basal area. Excavations of sapling roots suggest that root distribution is related to groundwater history. Therefore, a decline in water table relative to the condition under which roots developed may strand plant roots where they cannot obtain sufficient moisture. Plant response is likely mediated by other factors such as soil texture and stratigraphy, availability of precipitation-derived soil moisture, and physiological and morphological adaptations to water stress, and tree age. An understanding of the relationships between water table declines and plant response may enable land and water managers to avoid activities that are likely to stress desirable riparian vegetation.

  4. Distorted Froude-scaled Flume Analysis of Large Woody Debris

    NASA Astrophysics Data System (ADS)

    Wallerstein, N. P.; Alonso, C. V.; Bennett, S. J.; Thorne, C. R.

    2001-12-01

    This paper presents the results of a movable-boundary, distorted, Froude-scaled hydraulic model based on Abiaca Creek, a sand-bedded channel in northern Mississippi. The model was used to examine the geomorphic and hydraulic impact of simplified Large Woody Debris (LWD) elements. The theory of physical scale models is discussed and the method used to construct the LWD test channel is developed. The channel model had bed and banks molded from 0.8 mm sand, and flow conditions were just below the threshold of motion so that any sediment transport and channel adjustment were the result of the debris element. Dimensions and positions of LWD elements were determined using a Debris Jam Classification Model (Wallerstein et al., 1997). Elements were attached to a dynamometer to measure element drag forces, and channel adjustment was determined through detailed topographic surveys. The fluid drag force on the element decreased asymptotically over time as the channel boundary eroded around the element due to locally increased boundary shear stress. Total time for geomorphic adjustment computed for the prototype channel at the Q2 discharge (discharge occurring once every two years on average) was as short as 45 hours. The size, depth and position of scour holes, bank erosion and bars created by flow acceleration past the elements were found to be related to element length and position within the channel cross-section. Morphologies created by each debris element in the model channel were comparable with similar jams observed in the prototype channel.

  5. Woody riparian vegetation of Great Basin National Park. Interim report

    SciTech Connect

    Douglas, C.L.; Smith, S.D.; Murray, K.J.; Landau, F.H.; Sala, A.

    1994-07-01

    The community composition and population structure of the woody riparian vegetation in Great Basin National Park are described. Community analyses were accomplished by sampling 229 plots placed in a systematic random fashion along elevational gradients of 8 major stream systems (Baker, Big Wash, Lehman, Pine, Pole, Shingle, Snake, and Strawberry Creeks) in the Park using the releve method. Stand demographics were determined for the four dominant tree species in the Park, based on absolute stem counts at 15 sites along 6 major watersheds. Elevational ranges of the dominant tree and shrub species along 8 major streams were determined via transect analysis and systematic reconnaissance efforts. TWINSPAN (two-way indicator analysis) indentified 4 primary species groups and 8 stand groups in the Park. Because of the homogeneity of riparian zones, both presence and abundance of species were important parameters in determining species groups. Although species such as Populus tremuloides (aspen), Abies concolor (white fir) and Rosa woodsii (Woods rose) are very common throughout the Park, they are particularly abundant at higher, upper intermediate, and lower intermediate elevations.

  6. Direct hydrodeoxygenation of raw woody biomass into liquid alkanes.

    PubMed

    Xia, Qineng; Chen, Zongjia; Shao, Yi; Gong, Xueqing; Wang, Haifeng; Liu, Xiaohui; Parker, Stewart F; Han, Xue; Yang, Sihai; Wang, Yanqin

    2016-03-30

    Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with mass yields up to 28.1 wt% over a multifunctional Pt/NbOPO4 catalyst in cyclohexane. The superior performance of this catalyst allows simultaneous conversion of cellulose, hemicellulose and, more significantly, lignin fractions in the wood sawdust into hexane, pentane and alkylcyclohexanes, respectively. Investigation on the molecular mechanism reveals that a synergistic effect between Pt, NbOx species and acidic sites promotes this highly efficient hydrodeoxygenation of bulk lignocellulose. No chemical pretreatment of the raw woody biomass or separation is required for this one-pot process, which opens a general and energy-efficient route for converting raw lignocellulose into valuable alkanes.

  7. Direct hydrodeoxygenation of raw woody biomass into liquid alkanes

    PubMed Central

    Xia, Qineng; Chen, Zongjia; Shao, Yi; Gong, Xueqing; Wang, Haifeng; Liu, Xiaohui; Parker, Stewart F.; Han, Xue; Yang, Sihai; Wang, Yanqin

    2016-01-01

    Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with mass yields up to 28.1 wt% over a multifunctional Pt/NbOPO4 catalyst in cyclohexane. The superior performance of this catalyst allows simultaneous conversion of cellulose, hemicellulose and, more significantly, lignin fractions in the wood sawdust into hexane, pentane and alkylcyclohexanes, respectively. Investigation on the molecular mechanism reveals that a synergistic effect between Pt, NbOx species and acidic sites promotes this highly efficient hydrodeoxygenation of bulk lignocellulose. No chemical pretreatment of the raw woody biomass or separation is required for this one-pot process, which opens a general and energy-efficient route for converting raw lignocellulose into valuable alkanes. PMID:27025898

  8. Fertilization in short-rotation woody crops plantations

    SciTech Connect

    Johnson, D.W.

    1984-08-27

    Short-rotation woody crops (SRWC) plantations may be more responsive to fertilization than mature forests because they are in a nutrient-accumulating rather than a steady-state stage of stand development. On the other hand, the nutrient removals with more frequent harvesting (via biomass removal, leaching, erosion, etc.) may cause greater fertilizer loss from SRWC plantations than from mature forests. A knowledge of the mechanisms of fertilizer response is needed to optimize fertilization schemes for maximum response and to minimize losses and the undesirable environmental consequences associated with such losses. Nitrogen does not accumulate in mineral forms in soils, and, thus, responses must be due primarily to N conservation within plants themselves (translocation), within nutrient cycles, or by elevating non-mineral but labile soil N fractions. Nitrogen fertilization schemes in SRWC plantations most probably must rely on conservation within plants and elevating soil labile N levels to provide prolonged growth response. Attempts to keep soil mineral N levels elevated may very well lead to excessive nitrification, nitrate leaching, and associated problems with groundwater pollution. On the other hand, phosphorus and potassium may be retained in ionic forms in soils, and fertilizer schemes may be designed to take advantage of this property, as well as internal plant conservation in the case of phosphorus, to promote long-term responses. 27 references, 1 figure.

  9. Flow and scour constraints on uprooting of pioneer woody seedlings

    NASA Astrophysics Data System (ADS)

    Bywater-Reyes, Sharon; Wilcox, Andrew C.; Stella, John C.; Lightbody, Anne F.

    2015-11-01

    Scour and uprooting during flood events is a major disturbance agent that affects plant mortality rates and subsequent vegetation composition and density, setting the trajectory of physical-biological interactions in rivers. During flood events, riparian plants may be uprooted if they are subjected to hydraulic drag forces greater than their resisting force. We measured the resisting force of woody seedlings established on river bars with in situ lateral pull tests that simulated flood flows with and without substrate scour. We quantified the influence of seedling size, species (Populus and Tamarix), water-table depth, and scour depth on resisting force. Seedling size and resisting force were positively related with scour depth and water-table depth—a proxy for root length—exerting strong and opposing controls on resisting force. Populus required less force to uproot than Tamarix, but displayed a greater increase in uprooting force with seedling size. Further, we found that calculated mean velocities required to uproot seedlings were greater than modeled flood velocities under most conditions. Only when plants were either shallowly rooted or subjected to substrate scour (≥0.3 m) did the calculated velocities required for uprooting decrease to within the range of modeled flood velocities, indicating that drag forces alone are unlikely to uproot seedlings in the absence of extreme events or bar-scale sediment transport. Seedlings on river bars are most resilient to uprooting when they are large, deeply rooted, and unlikely to experience substrate scour, which has implications for ecogeomorphic evolution and river management.

  10. Laser Capture Microdissection Protocol for Xylem Tissues of Woody Plants

    PubMed Central

    Blokhina, Olga; Valerio, Concetta; Sokołowska, Katarzyna; Zhao, Lei; Kärkönen, Anna; Niittylä, Totte; Fagerstedt, Kurt

    2017-01-01

    Laser capture microdissection (LCM) enables precise dissection and collection of individual cell types from complex tissues. When applied to plant cells, and especially to woody tissues, LCM requires extensive optimization to overcome such factors as rigid cell walls, large central vacuoles, intercellular spaces, and technical issues with thickness and flatness of the sections. Here we present an optimized protocol for the laser-assisted microdissection of developing xylem from mature trees: a gymnosperm (Norway spruce, Picea abies) and an angiosperm (aspen, Populus tremula) tree. Different cell types of spruce and aspen wood (i.e., ray cells, tracheary elements, and fibers) were successfully microdissected from tangential, cross and radial cryosections of the current year’s growth ring. Two approaches were applied to achieve satisfactory flatness and anatomical integrity of the spruce and aspen specimens. The commonly used membrane slides were ineffective as a mounting surface for the wood cryosections. Instead, in the present protocol we use glass slides, and introduce a glass slide sandwich assembly for the preparation of aspen sections. To ascertain that not only the anatomical integrity of the plant tissue, but also the molecular features were not compromised during the whole LCM procedure, good quality total RNA could be extracted from the microdissected cells. This showed the efficiency of the protocol and established that our methodology can be integrated in transcriptome analyses to elucidate cell-specific molecular events regulating wood formation in trees. PMID:28101088

  11. The multiple fuzzy origins of woodiness within Balsaminaceae using an integrated approach. Where do we draw the line?

    PubMed Central

    Lens, Frederic; Eeckhout, Sharon; Zwartjes, Rosa; Smets, Erik; Janssens, Steven B.

    2012-01-01

    Background and Aims The family Balsaminaceae is essentially herbaceous, except for some woodier species that can be described as ‘woody’ herbs or small shrubs. The family is nested within the so-called balsaminoid clade of Ericales, including the exclusively woody families Tetrameristaceae and Marcgraviaceae, which is sister to the remaining families of the predominantly woody order. A molecular phylogeny of Balsaminaceae is compared with wood anatomical observations to find out whether the woodier species are derived from herbaceous taxa (i.e. secondary woodiness), or whether woodiness in the family represents the ancestral state for the order (i.e. primary woodiness). Methods Wood anatomical observations of 68 Impatiens species and Hydrocera triflora, of which 47 are included in a multigene phylogeny, are carried out using light and scanning electron microscopy and compared with the molecular phylogenetic insights. Key Results There is much continuous variation in wood development between the Impatiens species studied, making the distinction between herbaceousness and woodiness difficult. However, the most woody species, unambiguously considered as truly woody shrubs, all display paedomorphic wood features pointing to secondary woodiness. This hypothesis is further supported by the molecular phylogeny, demonstrating that these most woody species are derived from herbaceous (or less woody) species in at least five independent clades. Wood formation in H. triflora is mostly confined to the ribs of the stems and shows paedomorphic wood features as well, suggesting that the common ancestor of Balsaminaceae was probably herbaceous. Conclusions The terms ‘herbaceousness’ and ‘woodiness’ are notoriously difficult to use in Balsaminaceae. However, anatomical observations and molecular sequence data show that the woodier species are derived from less woody or clearly herbaceous species, demonstrating that secondary woodiness has evolved in parallel. PMID

  12. Dynamic aspects of large woody debris in river channels

    NASA Astrophysics Data System (ADS)

    Vergaro, Alexandra; Caporali, Enrica; Becchi, Ignazio

    2015-04-01

    Large Woody Debris (LWD) are an integral component of the fluvial environment. They represent an environmental resource, but without doubt they represent also a risk factor for the amplification that could give to the destructive power of a flood event. While countless intervention in river channels have reintroduced wood in rivers with restoration and banks protection aims, during several flash flood events LWD have had a great part in catastrophic consequences, pointing out the urgency of an adequate risk assessment procedure. At present wood dynamics in rivers is not systematically considered within the procedures for the elaboration of hazard maps resulting in loss of prediction accuracy and underestimation of hazard impacts. The assessment inconsistency comes from the complexity of the question: several aspects in wood processes are not yet well known and the superposition of different physical phenomena results in great difficulty to predict critical scenarios. The presented research activity has been aimed to improve management skills for the assessment of the hydrologic risk associated to the presence of large woody debris in rivers, improving knowledge about LWD dynamic processes and proposing effective tools for monitoring and mapping river catchments vulnerability. Utilizing critical review of the published works, field surveys and experimental investigations LWD damaging potential has been analysed to support the identification of the exposed sites and the redaction of hazard maps, taking into account that a comprehensive procedure has to involve: a) Identification of the critical cross sections; b) Evaluation of wood availability in the river catchment; c) Prediction of hazard scenarios through the estimation of water discharge, wood recruitment and entrainment, wood transport and destination. Particularly, a survey sheets form for direct measurements has been implemented and tested in field to provide an investigation instruments for wood and river

  13. Contributions of woody and herbaceous vegetation to tropical savanna ecosystem productivity: a quasi-global estimate.

    PubMed

    Lloyd, Jon; Bird, Michael I; Vellen, Lins; Miranda, Antonio Carlos; Veenendaal, Elmar M; Djagbletey, Gloria; Miranda, Heloisa S; Cook, Garry; Farquhar, Graham D

    2008-03-01

    To estimate the relative contributions of woody and herbaceous vegetation to savanna productivity, we measured the 13C/12C isotopic ratios of leaves from trees, shrubs, grasses and the surface soil carbon pool for 22 savannas in Australia, Brazil and Ghana covering the full savanna spectrum ranging from almost pure grassland to closed woodlands on all three continents. All trees and shrubs sampled were of the C3 pathway and all grasses of the C4 pathway with the exception of Echinolaena inflexa (Poir.) Chase, a common C3 grass of the Brazilian cerrado. By comparing the carbon isotopic compositions of the plant and carbon pools, a simple model relating soil delta 13C to the relative abundances of trees + shrubs (woody plants) and grasses was developed. The model suggests that the relative proportions of a savanna ecosystem's total foliar projected cover attributable to grasses versus woody plants is a simple and reliable index of the relative contributions of grasses and woody plants to savanna net productivity. Model calibrations against woody tree canopy cover made it possible to estimate the proportion of savanna productivity in the major regions of the world attributable to trees + shrubs and grasses from ground-based observational maps of savanna woodiness. Overall, it was estimated that 59% of the net primary productivity (Np) of tropical savannas is attributable to C4 grasses, but that this proportion varies significantly within and between regions. The C4 grasses make their greatest relative contribution to savanna Np in the Neotropics, whereas in African regions, a greater proportion of savanna Np is attributable to woody plants. The relative contribution of C4 grasses in Australian savannas is intermediate between those in the Neotropics and Africa. These differences can be broadly ascribed to large scale differences in soil fertility and rainfall.

  14. Soil organic carbon responses to grazing and woody plant encroachment in a semi-desert grassland

    NASA Astrophysics Data System (ADS)

    Throop, H. L.; Archer, S. R.; McClaran, M.; Ojima, D.; Keough, C.; Parton, W.

    2006-12-01

    The majority of carbon (C) in grassland and savanna ecosystems is belowground. Recent estimates suggest the historic and ongoing proliferation of woody plants in these systems may account for a significant fraction of the Northern Hemisphere carbon (C) sink. A large degree of uncertainty in the direction and magnitude of soil C pool response to woody encroachment exists, however. Soil organic C (SOC) response to woody encroachment may be modified by current and historical land management patterns, but the nature of these relationships is poorly understood. We used CENTURY, a process-based ecosystem model, to explore historical patterns and project future changes in SOC in response to Prosopis velutina encroachment and livestock grazing in a southern Arizona semi-desert grassland. We parameterized and adapted CENTURY for our study site using woody and herbaceous biomass data and P. velutina growth rate estimates. Modeled contemporary SOC levels were +/- 15% of measured levels. Simulations of historical grazing management suggest that grassland SOC dropped nearly 50% (from 1020 to 530 g C m-2) in response to heavy, continuous livestock grazing initiated around 1850. SOC recovery varied with the degree of relaxation of grazing intensity, with nearly full recovery occurring in areas where grazing was excluded between 1903 and 2005 (modeled SOC = 930 g C m-2 in 2005). Woody encroachment, beginning around 1900, had a strong positive influence on modeled SOC, with the greatest accumulations associated with plants greater than 60 years old. Grazing mediated this response, such that sub-canopy SOC in grazed areas was 200-300 g C m-2 less than that in ungrazed areas. Forward simulations suggest that SOC will continue to increase until woody plant stands reach ca. 130 years of age, at which point SOC will stabilize around 3300 g C m^{- 2} for grazed sites and 3000 g C m-2 for ungrazed sites. Results indicate that woody plant encroachment has strong positive influence on SOC

  15. Photosynthetic pathway alters hydraulic structure and function in woody plants.

    PubMed

    Kocacinar, Ferit; Sage, Rowan F

    2004-04-01

    Xylem structure and function is proposed to reflect an evolutionary balance between demands for efficient movement of water to the leaf canopy and resistance to cavitation during high xylem tension. Water use efficiency (WUE) affects this balance by altering the water cost of photosynthesis. Therefore species of greater WUE, such as C(4) plants, should have altered xylem properties. To evaluate this hypothesis, we assessed the hydraulic and anatomical properties of 19 C(3) and C(4) woody species from arid regions of the American west and central Asia. Specific conductivity of stem xylem ( K(s) ) was 16%-98% lower in the C(4) than C(3) shrubs from the American west. In the Asian species, the C(3) Nitraria schoberi had similar and Halimodendron halodendron higher K(s) values compared with three C(4) species. Leaf specific conductivity ( K(L); hydraulic conductivity per leaf area) was 60%-98% lower in the C(4) than C(3) species, demonstrating that the presence of the C(4) pathway alters the relationship between leaf area and the ability of the xylem to transport water. C(4) species produced similar or smaller vessels than the C(3) shrubs except in Calligonum, and most C(4) shrubs exhibited higher wood densities than the C(3) species. Together, smaller conduit size and higher wood density indicate that in most cases, the C(4) shrubs exploited higher WUE by altering xylem structure to enhance safety from cavitation. In a minority of cases, the C(4) shrubs maintained similar xylem properties but enhanced the canopy area per branch. By establishing a link between C(4) photosynthesis and xylem structure, this study indicates that other phenomena that affect WUE, such as atmospheric CO(2) variation, may also affect the evolution of wood structure and function.

  16. The Geomorphic Role of Large Woody Debris in River Avulsions

    NASA Astrophysics Data System (ADS)

    Stout, J. C.; Grove, J. R.; Rutherfurd, I.; Marren, P.

    2014-12-01

    The avulsion or abandonment of a river channel in favor of a new course on the floodplain is integral to the development and maintenance of anabranching planforms. Avulsions tend to occur on rivers where the rate of vertical aggradation outpaces lateral migration. In fine cohesive floodplain sediments, avulsions evolve through five stages dependent on the amount of flow and sediment being captured by the new channel. There is limited data available to allow the prediction of autogenic and allogenic controls on: the time over which an avulsion is active; its likely location; the frequency of occurrence; and the length of the interavulsion period. The delivery of wood to the river channel is an autogenic process which has received much attention over the last three decades. Surprisingly it has not previously been considered in anabranch avulsions, apart from where log-jams entirely block channels. The presence of large woody debris in the channel acts as a roughness element, trapping, and impeding the movement of sediments and deflecting flow onto the floodplain. We hypothesize that the delivery rates of wood to the channel, and its subsequent configuration (i.e. dimension, amount, volume, spatial arrangement and blockage ratio), alters flow and sediment routing through the channel. These changes directly influence the stages of avulsion development. To test this conceptual model we have used eleven floodplain cores to reconstruct the timing of a Holocene avulsion. The morphology of the channel in each evolutionary stage was used to estimate the relative role of wood as a roughness element. This was done by coupling a mass balance wood delivery model, run in a Monte Carlo simulation, to the geomorphic processes of each evolutionary stage of the avulsion. Our results allow us to quantify the importance of in-channel wood during each stage of the avulsion. These data highlight that there are critical points in the evolution of anabranching channels when large wood

  17. Field and flume investigations of the effects of logjams and woody debris on streambed morphology

    NASA Astrophysics Data System (ADS)

    Leung, V.; Montgomery, D. R.; McHenry, M. L.

    2014-12-01

    Interactions among wood debris, fluid flow and sediment transport in rivers are first-order controls on channel morphodynamics, affecting streambed morphology, sediment transport, sediment storage and aquatic habitat. Woody debris increases the hydraulic and topographic complexity in rivers, leading to a greater diversity of aquatic habitats and an increase in the number of large pools that are important fish habitat and breeding grounds. In the past decade, engineered logjams have become an increasingly used tool in river management for simultaneously decreasing the rate of riverbank migration and improving aquatic habitat. Sediment deposits around woody debris build up riverbanks and counteract bank migration caused by erosion. Previous experiments on flow visualization around model woody debris suggest the amount of sediment scour and deposition are primarily related to the presence of roots and the obstructional area of the woody debris. We present the results of fieldwork and sediment transport experiments of streambed morphology around stationary woody debris. Field surveys on the Hoh River and the Elwha River, WA, measure the local streambed morphology around logjams and individual pieces of woody debris. We quantified the amount of local scour and dam-removal related fine sediment deposition around natural and engineered logjams of varying sizes and construction styles, located in different geomorphic settings. We also quantified the amount of local scour around individual pieces of woody debris of varying sizes, geometries and orientations relative to flow. The flume experiments tested the effects of root geometry and log orientation of individual stationary trees on streambed morphology. The flume contained a deformable sediment bed of medium sand. We find that: 1) the presence of roots on woody debris leads to greater areas of both sediment scour and deposition; and 2) the amount of sediment scour and deposition are related to the wood debris cross

  18. Intertidal coarse woody debris: A spatial subsidy as shelter or feeding habitat for gastropods?

    NASA Astrophysics Data System (ADS)

    Storry, Kristin A.; Weldrick, Christine K.; Mews, Malte; Zimmer, Martin; Jelinski, Dennis E.

    2006-01-01

    Coarse woody debris (CWD) in the intertidal region of rocky shores serves as a potential source of nutrients as well as habitat or refugia from predation, ecologically linking the adjacent marine and terrestrial habitats. In a series of field and laboratory experiments, the affinity of slow-moving motile intertidal gastropods to CWD either as food source or as shelter that increases habitat complexity was tested. In intertidal pools, CWD did not increase colonization by Littorina spp., while it did so in supratidal pools. Habitat complexity, brought about by algal cover and barnacles, was apparently sufficient in intertidal pools without woody debris, while the increase in habitat complexity by CWD increased the attractiveness of supratidal pools with little natural complexity to Littorina spp. Overall, however, comparison of pools containing woody debris and those containing artificial shelter provided evidence for CWD, and/or its biofilm, serving as food source rather than refugium per se. Similarly, Tegula funebralis chose CWD as food source rather than as shelter as indicated by comparison of autoclaved and unmanipulated woody debris. Further, both unfed and fed snails from a site where CWD was present significantly preferred CWD over macroalgae. Among snails from a site without woody debris, fed individuals showed no preference, while unfed snails significantly preferred macroalgae. From this, experience appears to be a factor that mediates the role of CWD. Overall, however, CWD appears to provide supplementary food to snails in the inter- and supratidal zone.

  19. Trends in soil erosion and woody shrub encroachment in Ngqushwa district, Eastern Cape Province, South Africa.

    PubMed

    Manjoro, Munyaradzi; Kakembo, Vincent; Rowntree, Kate M

    2012-03-01

    Woody shrub encroachment severely impacts on the hydrological and erosion response of rangelands and abandoned cultivated lands. These processes have been widely investigated at various spatial scales, using mostly field experimentation. The present study used remote sensing to investigate spatial and temporal patterns of soil erosion and encroachment by a woody shrub species, Pteronia incana, in a catchment in Ngqushwa district, Eastern Cape Province, South Africa between 1998 and 2008. The extreme categories of soil erosion and shrub encroachment were mapped with higher accuracy than the intermediate ones, particularly where lower spatial resolution data were used. The results showed that soil erosion in the worst category increased simultaneously with dense woody shrub encroachment on the hill slopes. This trend is related to the spatial patterning of woody shrub vegetation that increases bare soil patches--leading to runoff connectivity and concentration of overland flow. The major changes in soil erosion and shrub encroachment analysed during the 10-year period took place in the 5-9° slope category and on the concave slope form. Multi-temporal analyses, based on remote sensing, can extend our understanding of the dynamics of soil erosion and woody shrub encroachment. They may help benchmark the processes and assist in upscaling field studies.

  20. Woody encroachment and forest degradation in sub-Saharan Africa's woodlands and savannas 1982-2006.

    PubMed

    Mitchard, Edward T A; Flintrop, Clara M

    2013-01-01

    We review the literature and find 16 studies from across Africa's savannas and woodlands where woody encroachment dominates. These small-scale studies are supplemented by an analysis of long-term continent-wide satellite data, specifically the Normalized Difference Vegetation Index (NDVI) time series from the Global Inventory Modeling and Mapping Studies (GIMMS) dataset. Using dry-season data to separate the tree and grass signals, we find 4.0% of non-rainforest woody vegetation in sub-Saharan Africa (excluding West Africa) significantly increased in NDVI from 1982 to 2006, whereas 3.52% decreased. The increases in NDVI were found predominantly to the north of the Congo Basin, with decreases concentrated in the Miombo woodland belt. We hypothesize that areas of increasing dry-season NDVI are undergoing woody encroachment, but the coarse resolution of the study and uncertain relationship between NDVI and woody cover mean that the results should be interpreted with caution; certainly, these results do not contradict studies finding widespread deforestation throughout the continent. However, woody encroachment could be widespread, and warrants further investigation as it has important consequences for the global carbon cycle and land-climate interactions.

  1. Bryophyte species associations with coarse woody debris and stand ages in Oregon

    USGS Publications Warehouse

    Rambo, T.; Muir, Patricia S.

    1998-01-01

    We quantified the relationships of 93 forest floor bryophyte species, including epiphytes from incorporated litterfall, to substrate and stand age in Pseudotsuga menziesii-Tsuga heterophylla stands at two sites in western Oregon. We used the method of Dufr??ne and Legendre that combines a species' relative abundance and relative frequency, to calculate that species' importance in relation to environmental variables. The resulting 'indicator value' describes a species' reliability for indicating the given environmental parameter. Thirty-nine species were indicative of either humus, a decay class of coarse woody debris, or stand age. Bryophyte community composition changed along the continuum of coarse woody debris decomposition from recently fallen trees with intact bark to forest floor humus. Richness of forest floor bryophytes will be enhanced when a full range of coarse woody debris decay classes is present. A suite of bryophytes indicated old-growth forest. These were mainly either epiphytes associated with older conifers or liverworts associated with coarse woody debris. Hardwood-associated epiphytes mainly indicated young stands. Mature conifers, hardwoods, and coarse woody debris are biological legacies that can be protected when thinning managed stands to foster habitat complexity and biodiversity, consistent with an ecosystem approach to forest management.

  2. Reforestation of bottomland hardwoods and the issue of woody species diversity

    USGS Publications Warehouse

    Allen, J.A.

    1997-01-01

    Bottomland hardwood forests in the southcentral United States have been cleared extensively for agriculture, and many of the remaining forests are fragmented and degraded. During the last decade, however, approximately 75,000 ha of land-mainly agricultural fields-have been replanted or contracted for replanting, with many more acres likely to be reforested in the near future. The approach used in most reforestation projects to date has been to plant one to three overstory tree species, usually Quercus spp. (oaks), and to rely on natural dispersal for the establishment of other woody species. I critique this practice by two means. First, a brief literature review demonstrates that moderately high woody species diversity occurs in natural bottomland hardwood forests in the region. This review, which relates diversity to site characteristics, serves as a basis for comparison with stands established by means of current reforestation practices. Second, I reevaluate data on the invasion of woody species from an earlier study of 10 reforestation projects in Mississippi,with the goal of assessing the likelihood that stands with high woody species diversity will develop. I show that natural invasion cannot always be counted on to produce a diverse stand, particularly on sites more than about 60 m from an existing forest edge. I then make several recommendations for altering current reforestation pactices in order to establish stands with greater woody species diversity, a more natural appearance,and a more positive environmental impact at scales larger than individual sites.

  3. Induced somatic sector analysis of cellulose synthase (CesA) promoter regions in woody stem tissues.

    PubMed

    Creux, Nicky M; Bossinger, Gerd; Myburg, Alexander A; Spokevicius, Antanas V

    2013-03-01

    The increasing focus on plantation forestry as a renewable source of cellulosic biomass has emphasized the need for tools to study the unique biology of woody genera such as Eucalyptus, Populus and Pinus. The domestication of these woody crops is hampered by long generation times, and breeders are now looking to molecular approaches such as marker-assisted breeding and genetic modification to accelerate tree improvement. Much of what is known about genes involved in the growth and development of plants has come from studies of herbaceous models such as Arabidopsis and rice. However, transferring this information to woody plants often proves difficult, especially for genes expressed in woody stems. Here we report the use of induced somatic sector analysis (ISSA) for characterization of promoter expression patterns directly in the stems of Populus and Eucalyptus trees. As a case study, we used previously characterized primary and secondary cell wall-related cellulose synthase (CesA) promoters cloned from Eucalyptus grandis. We show that ISSA can be used to elucidate the phloem and xylem expression patterns of the CesA genes in Eucalyptus and Populus stems and also show that the staining patterns differ in Eucalyptus and Populus stems. These findings show that ISSA is an efficient approach to investigate promoter function in the developmental context of woody plant tissues and raise questions about the suitability of heterologous promoters for genetic manipulation in plant species.

  4. The contribution of woody plant materials on the several conditions in a space environment

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Abe, Yusuke; Katayama, Takeshi

    Woody plant materials have several utilization elements in our habitation environment on earth. The studies of woody plants under a space-environment in the vegetable kingdom have a high contribution to the study of various and exotic environmental responses, too. Woody plants can produce an excess oxygen, woody materials for the living cabin, and provide a biomass by cultivating crops and other species of creatures. Tree material would become to be a tool in closed bio-ecosystems such as an environment in a space. We named the trees used as material for the experiment related to space environments “CosmoBon”, small tree bonsai. Japanese cherry tree, “Sakura”, is famous and lovely tree in Japan. One species of “Sakura”, “Mamezakura, Prunus incisa”, is not only lovely tree species, but also suitable tree for the model tree of our purpose. The species of Prunus incisa is originally grown in volcano environment. That species of Sakura is originally grown on Mt. Fuji aria, oligotrophic place. We will try to build the best utilization usage of woody plant under the space environment by “Mamezakura” as a model tree. Here, we will show the importance of uniformity of materials when we will use the tree materials in a space environment. We will also discuss that tree has a high possibility of utilization under the space environments by using our several results related to this research.

  5. Island colonization and evolution of the insular woody habit in Echium L. (Boraginaceae).

    PubMed Central

    Böhle, U R; Hilger, H H; Martin, W F

    1996-01-01

    Numerous island-inhabiting species of predominantly herbaceous angiosperm genera are woody shrubs or trees. Such "insular woodiness" is strongly manifested in the genus Echium, in which the continental species of circummediterranean distribution are herbaceous, whereas endemic species of islands along the Atlantic coast of north Africa are woody perennial shrubs. The history of 37 Echium species was traced with 70 kb of noncoding DNA determined from both chloroplast and nuclear genomes. In all, 239 polymorphic positions with 137 informative sites, in addition to 27 informative indels, were found. Island-dwelling Echium species are shown to descend from herbaceous continental ancestors via a single island colonization event that occurred < 20 million years ago. Founding colonization appears to have taken place on the Canary Islands, from which the Madeira and Cape Verde archipelagos were invaded. Colonization of island habitats correlates with a recent origin of perennial woodiness from herbaceous habit and was furthermore accompanied by intense speciation, which brought forth remarkable diversity of forms among contemporary island endemics. We argue that the origin of insular woodiness involved response to counter-selection of inbreeding depression in founding island colonies. Images Fig. 1 Fig. 3 PMID:8876207

  6. Thermochemical pretreatment of underutilized woody biomass for manufacturing wood composites

    NASA Astrophysics Data System (ADS)

    Pelaez Samaniego, Manuel Raul

    Prescribed fires, one method for reducing hazardous fuel loads from forest lands in the US, are limited by geographical, environmental, and social impacts. Mechanical operations are an alternative type of fuel treatment but these processes are constrained by the difficulty of economically harvesting and/or using large amounts of low-value woody biomass. Adoption and integration of new technologies into existing wood composite facilities offer better utilization of this material. A pretreatment that enables integration of technologies in a typical composite facility will aid with diversification of product portfolio (e.g. wood composites, fuel pellets, liquid fuels, chemicals). Hot water extraction (HWE) is an option for wood pretreatment. This work provides a fundamental understanding of the physicochemical changes to wood resulting from HWE, and how these changes impact processing and performance of composites. Specific objectives were to: 1) review literature on studies related to the manufacture of composites produced with thermally pretreated wood, 2) manufacture wood plastic composites (WPC) and particleboard using HWE wood and evaluate the impacts of pretreatment on product properties, 3) develop an understanding of the effect of HWE on lignin properties, specifically lignin at the cells surface level after migration from cell walls and middle lamella, 4) discern the influence of lignin on the fiber surface on processing WPCs, and, 5) investigate the effect of changing the pretreatment environment (inert gas instead of water) on lignin behavior. Results show that HWE enhances the resistance of both WPCs and particleboard to water with positive or no effect on mechanical properties. Reduction of hemicelluloses and lignin property changes are suggested as the main reasons for enhancing interaction between wood fiber and resins during composite processing. Lignin on the surface of particles after HWE interacts with thermoplastics during WPCs compounding, thus

  7. Changes in flowering phenology of woody plants in North China

    NASA Astrophysics Data System (ADS)

    Dai, Junhu

    2016-04-01

    Over the past several decades, abundant evidences proved that the first flowering date of plants in northern hemisphere became earlier in response to climate warming. However, the existing results about impact of climate change on flowering duration are controversial. In this study, we studied temporal trends in first flowering date (FFD), end of flowering date (EFD) and flowering duration (FD) of 94 woody plants from 1963 to 2014 at three stations (Harbin, Beijing and Xi'an) in North China. Meanwhile, we analyzed the relationship between length of flowering periods and temperature using two phenological models (including regression model and growing degree day model). At all stations, more than 90% of observed species showed earlier flowering over time from 1963 to 2014. The average trends in FFD were 1.33, 1.77 and 3.01 days decade-1 at Harbin, Beijing and Xi'an, respectively. During the same period, EFD also became earlier by a mean rate of 2.19, 1.39 and 2.00 days decade-1, respectively. Regarding FD, a significant shortening of FD was observed at Harbin (-0.86 days decade-1), but FD extended by 0.37 and 1.01 days decade-1 at Beijing and Xi'an, respectively. At interspecific level, the plant species with longer FD tend to have stronger trends of FD extension. Through regression analyses, we found more than 85% of time series revealed a significant negative relationship between FFD (or EFD) and preseason temperature. The regression model could simulate the interannual changes in FFD and EFD with the mean goodness of fit (R2) ranging from 0.38 to 0.67, but failed to simulate the FD accurately, as R2 ranging from 0.09 to 0.18. Regarding to FFD and EFD, the growing degree day model could improved R2 of simuation, but also could not simulate FD accurately. Therefore, we concluded that the FFD and EFD advanced notably in recent six decades as a result of climate warming, but the direction of FD changes depended on locations and the species involved. In addition, the

  8. Nitrogen uptake and turnover in riparian woody vegetation.

    PubMed

    Chambers, Chris; Marshall, John D; Danehy, Robert J

    2004-06-01

    The nutrient balance of streams and adjacent riparian ecosystems may be modified by the elimination of anadromous fish runs and perhaps by forest fertilization. To better understand nitrogen (N) dynamics within stream and riparian ecosystems we fertilized two streams and their adjacent riparian corridors in central Idaho. On each stream two nitrogen doses were applied to a swathe approximately 35 m wide centered on the stream. The fertilizer N was enriched in 15N to 18 per thousand. This enrichment is light relative to many previous labeling studies, yet sufficient to yield a traceable signal in riparian and stream biota. This paper reports pre-treatment differences in delta15N and the first-year N response to fertilizer within the riparian woody plant community. Future papers will describe the transfer of allochthonous litter N to the stream and its subsequent processing by stream biota. Pre-treatment delta15N differed between the two creeks (P=0.0002), possibly due to residual salmon nitrogen in one of the creeks. Pre-treatment delta15N of current-year needles was enriched compared to leaf litter, which was in turn enriched compared to needles aged 4 years and older. We conclude that fractionation due to retranslocation occurs in at least two phases. The first phase, which optimizes allocation of N in younger needle age classes, is distinctly different from the second, which conserves N prior to abscission. The delta15N difference between creeks was eliminated by the fertilization (P=0.42). In the two dominant conifer species, Abies lasiocarpa and Picea engelmannii, most fertilizer N was found in the current-year foliage; little was found in older needles and none was detected in litter (P=0.53). The only N-fixing shrub species, Alnus incana, took up only a small amount of fertilizer N [mean percent N derived from fertilizer (%Ndff) 5.0+/-1.6% (SE)]. Far more fertilizer N was taken up by other deciduous shrubs (mean %Ndff=33.9+/-4.5%). Fertilizer N made up 25

  9. The toughness of secondary cell wall and woody tissue

    PubMed Central

    Lucas, P. W.; Tan, H. T. W.; Cheng, P. Y.

    1997-01-01

    The 'across grain' toughness of 51 woods has been determined on thin wet sections using scissors. The moisture content of sections and the varying sharpness of the scissor blades had little effect on the results. In thin sections (less than 0.6mm), toughness rose linearly with section thickness. The intercept toughness at zero thickness, estimated from regression analysis, was proportional to relative density, consistent with values reported for non-woody plant tissues. Extrapolation of the intercept toughness of these woods and other plant tissues/materials to a relative density of 1.0 predicted a toughness of 3.45kJ m-2 , which we identify with the intrinsic toughness of the cell wall. This quantity appears to predict published results from KIC tests on woods and is related to the propensity for crack deflection. The slope of the relationship between section thickness and toughness, describing the work of plastic buckling of cells, was not proportional to relative density, the lightest (balsa) and heaviest (lignum vitae) woods fracturing with less plastic work than predicted. The size of the plastic zone around the crack tip was estimated to be 0.5mm in size. From this, the hypothetical overall toughness of a thick (greater than 1 mm) block of solid cell wall material was calculated as 39.35 kJ m-2, due to both cell wall resistance (10 per cent) and the plastic buckling of cells (90 per cent). This value successfully predicts the toughness of most commercial woods (of relative densities between 0.2 and 0.8) from 'work area' tests in tension and bending. Though density was the most important factor, both fibre width/fibre length (in hardwoods) and lignin/cellulose ratios were negatively correlated with the work of plastic buckling, after correcting for density. At low densities the work of plastic buckling in the longitudinal radial (LR) direction exceeded that in longitudinal tangential (LT), but the reverse was true for relative densities above 0.25. This could

  10. Predicting the Effects of Woody Encroachment on Mammal Communities, Grazing Biomass and Fire Frequency in African Savannas.

    PubMed

    Smit, Izak P J; Prins, Herbert H T

    2015-01-01

    With grasslands and savannas covering 20% of the world's land surface, accounting for 30-35% of worldwide Net Primary Productivity and supporting hundreds of millions of people, predicting changes in tree/grass systems is priority. Inappropriate land management and rising atmospheric CO2 levels result in increased woody cover in savannas. Although woody encroachment occurs world-wide, Africa's tourism and livestock grazing industries may be particularly vulnerable. Forecasts of responses of African wildlife and available grazing biomass to increases in woody cover are thus urgently needed. These predictions are hard to make due to non-linear responses and poorly understood feedback mechanisms between woody cover and other ecological responders, problems further amplified by the lack of long-term and large-scale datasets. We propose that a space-for-time analysis along an existing woody cover gradient overcomes some of these forecasting problems. Here we show, using an existing woody cover gradient (0-65%) across the Kruger National Park, South Africa, that increased woody cover is associated with (i) changed herbivore assemblage composition, (ii) reduced grass biomass, and (iii) reduced fire frequency. Furthermore, although increased woody cover is associated with reduced livestock production, we found indigenous herbivore biomass (excluding elephants) remains unchanged between 20-65% woody cover. This is due to a significant reorganization in the herbivore assemblage composition, mostly as a result of meso-grazers being substituted by browsers at increasing woody cover. Our results suggest that woody encroachment will have cascading consequences for Africa's grazing systems, fire regimes and iconic wildlife. These effects will pose challenges and require adaptation of livelihoods and industries dependent on conditions currently prevailing.

  11. Predicting the Effects of Woody Encroachment on Mammal Communities, Grazing Biomass and Fire Frequency in African Savannas

    PubMed Central

    Smit, Izak P. J.; Prins, Herbert H. T.

    2015-01-01

    With grasslands and savannas covering 20% of the world’s land surface, accounting for 30–35% of worldwide Net Primary Productivity and supporting hundreds of millions of people, predicting changes in tree/grass systems is priority. Inappropriate land management and rising atmospheric CO2 levels result in increased woody cover in savannas. Although woody encroachment occurs world-wide, Africa’s tourism and livestock grazing industries may be particularly vulnerable. Forecasts of responses of African wildlife and available grazing biomass to increases in woody cover are thus urgently needed. These predictions are hard to make due to non-linear responses and poorly understood feedback mechanisms between woody cover and other ecological responders, problems further amplified by the lack of long-term and large-scale datasets. We propose that a space-for-time analysis along an existing woody cover gradient overcomes some of these forecasting problems. Here we show, using an existing woody cover gradient (0–65%) across the Kruger National Park, South Africa, that increased woody cover is associated with (i) changed herbivore assemblage composition, (ii) reduced grass biomass, and (iii) reduced fire frequency. Furthermore, although increased woody cover is associated with reduced livestock production, we found indigenous herbivore biomass (excluding elephants) remains unchanged between 20–65% woody cover. This is due to a significant reorganization in the herbivore assemblage composition, mostly as a result of meso-grazers being substituted by browsers at increasing woody cover. Our results suggest that woody encroachment will have cascading consequences for Africa’s grazing systems, fire regimes and iconic wildlife. These effects will pose challenges and require adaptation of livelihoods and industries dependent on conditions currently prevailing. PMID:26379249

  12. Biological approach for pulping and bleaching of non-woody plants

    SciTech Connect

    Sabharwal, H.S.; Young, R.A.; Blanchette, R.A.

    1996-10-01

    In recent years the pulp and paper industry has expressed serious concerns regarding energy reduction and pollution abatement. These concerns are being vigorously addressed in a variety of ways including the use of biological approaches for pulping and bleaching of wood. We are also evaluating the substitution of wood with non-woody plants for the conservation of forests. Our initial investigation on biomechanical pulping of bast fibers has given very promising results with respect to saving in energy consumption and enhancement of pulp strength properties. Preliminary studies on a biomimetic approach for delignification of non-woody plant pulps using natural bovine heme and synthetic tetraphenyl-porphyrin iron (III) chloride in combination with tert-butyl hydroperoxide (TBH) have also been conducted with some promise. The paper also briefly reviews the advancements made in biological approach for pulping and bleaching of non-woody plants.

  13. Environmental Determinants of Woody Plant Diversity at a Regional Scale in China

    PubMed Central

    Qian, Hong

    2013-01-01

    Understanding what drives the geographic variation of species richness across the globe is a fundamental goal of ecology and biogeography. Environmental variables have been considered as drivers of global diversity patterns but there is no consensus among ecologists on what environmental variables are primary drivers of the geographic variation of species richness. Here, I examine the relationship of woody plant species richness at a regional scale in China with sixteen environmental variables representing energy availability, water availability, energy-water balance, seasonality, and habitat heterogeneity. I found that temperature seasonality is the best predictor of woody species richness in China. Other important environmental variables include annual precipitation, mean temperature of the coldest month, and potential evapotranspiration. The best model explains 85% of the variation in woody plant species richness at the regional scale in China. PMID:24086642

  14. Woody plant richness does not influence invertebrate community reassembly trajectories in a tree diversity experiment.

    PubMed

    Yeeles, Peter; Lach, Lori; Hobbs, Richard J; van Wees, Mary; Didham, Raphael K

    2017-02-01

    Understanding the relationship between plant diversity and diversity at higher trophic levels is important from both conservation and restoration perspectives. Although there is strong evidence for bottom-up maintenance of biodiversity, this is based largely on studies of simplified grassland systems. Recently, studies in the TreeDivNet global network of tree diversity experiments have begun to test whether these findings are generalizable to more complex ecosystems, such as woodlands. We monitored invertebrate community reassembly over 5 yr of experimental woodland restoration at the TreeDivNet Ridgefield site in southwest Australia, testing the effects of woody plant species richness and herb-layer manipulation on invertebrate community structure and ant species composition. From 2010 to 2014, we sampled ground-dwelling invertebrates using pitfall traps in herbicide vs. no-herbicide subplots nested within each of 10 woody plant treatments varying in richness from zero (bare controls) to eight species, which produced a total of 211, 235 invertebrates, including 98, 979 ants belonging to 74 species. In mixed model analyses, the presence of woody plants was an important driver of faunal community reassembly (relative to bare control plots), but faunal responses to woody plant treatment combinations were idiosyncratic and unrelated to woody plant richness across treatments. We also found that a herbicide-induced reduction in herbaceous plant cover and richness had a positive effect on ant richness and caused more rapid convergence of invertebrate community composition toward the composition of a woodland reference site. These findings show that woody plant richness did not have direct positive effects on the diversity and community reassembly trajectories of higher trophic levels in our woodland system. From a management perspective, this suggests that even low-diversity restoration or carbon sequestration plantings can potentially lead to faunal reassembly outcomes

  15. Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

    USGS Publications Warehouse

    Sankey, Temuulen; Shrestha, Rupesh; Sankey, Joel B.; Hardgree, Stuart; Strand, Eva

    2013-01-01

    Woody encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global- and continental-scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high-resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar-derived height and crown area as predictors (Adj. R2 = 0.76, p 2. Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 – 143.6 kg and 0.5 – 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.

  16. Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

    NASA Astrophysics Data System (ADS)

    Sankey, Temuulen; Shrestha, Rupesh; Sankey, Joel B.; Hardegree, Stuart; Strand, Eva

    2013-07-01

    encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global- and continental-scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high-resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar-derived height and crown area as predictors (Adj. R2 = 0.76, p < 0.001, RMSE = 0.58 kg). The predicted mean aboveground woody carbon storage for the study area was 677 g/m2. Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 - 143.6 kg and 0.5 - 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.

  17. Landsat-Based Woody Vegetation Cover Monitoring in Southern African Savannahs

    NASA Astrophysics Data System (ADS)

    Symeonakis, E.; Petroulaki, K.; Higginbottom, T.

    2016-06-01

    Mapping woody cover over large areas can only be effectively achieved using remote sensing data and techniques. The longest continuously operating Earth-observation program, the Landsat series, is now freely-available as an atmospherically corrected, cloud masked surface reflectance product. The availability and length of the Landsat archive is thus an unparalleled Earth-observation resource, particularly for long-term change detection and monitoring. Here, we map and monitor woody vegetation cover in the Northwest Province of South Africa, an area of more than 100,000 km2 covered by 11 Landsat scenes. We employ a multi-temporal approach with dry-season data from 7 epochs between 1990 to 2015. We use 0.5 m-pixel colour aerial photography to collect > 15,000 point samples for training and validating Random Forest classifications of (i) woody vegetation cover, (ii) other vegetation types (including grasses and agricultural land), and (iii) non-vegetated areas (i.e. urban areas and bare land). Overall accuracies for all years are around 80 % and overall kappa between 0.45 and 0.66. Woody vegetation covers a quarter of the Province and is the most accurately mapped class (balanced accuracies between 0.74-0.84 for the 7 epochs). There is a steady increase in woody vegetation cover over the 25-year-long period of study in the expense of the other vegetation types. We identify potential woody vegetation encroachment 'hot-spots' where mitigation measures might be required and thus provide a management tool for the prioritisation of such measures in degraded and food-insecure areas.

  18. Modeling wave effects on limits of woody vegetation in Catahoula Lake, LA, USA

    NASA Astrophysics Data System (ADS)

    Edwards, B. L.; Curcic, M.; Keim, R.

    2014-12-01

    Exposure to water waves in lakes is an important control on the structure and distribution of both submerged and shoreline vegetative communities. Wave exposure incident on the shoreline limits the distribution of shrubs on both lake and coastal margins by preventing establishment of seedlings via bed disturbance and uprooting. The goal of this study is to investigate the relationship between bed stress due to wave action and the spatial distribution of woody seedling establishment in Catahoula Lake, Louisiana, USA. The lake bed consists of a broad, seasonally inundated flat bordered by a band of woody shrubs. Annual summer de-watering of the lake allows the lake bed to support a moist-soil herbaceous vegetation community, but recent encroachment by woody shrubs over the past ~70 years threatens ecosystem conversion. We use the University of Miami Wave Model (UMWM) to simulate surface wave evolution and bed shear stress for a range of dominant wind conditions and water levels. UMWM is a 3rdgeneration ocean wave model that solves the wave energy balance equation given wind forcing input. While the model has been previously validated in deep water and coastal ocean applications, this study validates the model in very shallow water where bed-induced wave dissipation is a significant process. Model results show that waves of sufficient energy to prevent establishment or to uproot seedlings are common in areas of the lake that are experiencing the least woody encroachment. Areas of the lake bed that are experiencing encroachment are often sheltered from the strongest waves due to the lakes orientation with respect to dominant winds and prior establishment of woody growth, which dissipates wave energy significantly. Results are consistent with some otherwise-unexplained conditions at the lake such as spatially inconsistent relationships between elevation and vegetation communities. We use model results to investigate feedbacks between woody encoachment (both new and

  19. Structure Measurements of Leaf and Woody Components of Forests with Dual-Wavelength Lidar Scanning Data

    NASA Astrophysics Data System (ADS)

    Strahler, A. H.; Li, Z.; Schaaf, C.; Howe, G.; Martel, J.; Hewawasam, K.; Douglas, E. S.; Chakrabarti, S.; Cook, T.; Paynter, I.; Saenz, E. J.; Wang, Z.; Woodcock, C. E.; Jupp, D. L. B.; Schaefer, M.; Newnham, G.

    2014-12-01

    Forest structure plays a critical role in the exchange of energy, carbon and water between land and atmosphere and nutrient cycle. We can provide detailed forest structure measurements of leaf and woody components with the Dual Wavelength Echidna® Lidar (DWEL), which acquires full-waveform scans at both near-infrared (NIR, 1064 nm) and shortwave infrared (SWIR, 1548 nm) wavelengths from simultaneous laser pulses. We collected DWEL scans at a broadleaf forest stand and a conifer forest stand at Harvard Forest in June 2014. Power returned from leaves is much lower than from woody materials such as trunks and branches at the SWIR wavelength due to the liquid water absorption by leaves, whereas returned power at the NIR wavelength is similar from both leaves and woody materials. We threshold a normalized difference index (NDI), defined as the difference between returned power at the two wavelengths divided by their sum, to classify each return pulse as a leaf or trunk/branch hit. We obtain leaf area index (LAI), woody area index (WAI) and vertical profiles of leaf and woody components directly from classified lidar hits without empirical wood-to-total ratios as are commonly used in optical methods of LAI estimation. Tree heights, diameter at breast height (DBH), and stem count density are the other forest structure parameters estimated from our DWEL scans. The separation of leaf and woody components in tandem with fine-scale forest structure measurements will benefit studies on carbon allocation of forest ecosystems and improve our understanding of the effects of forest structure on ecosystem functions. This research is supported by NSF grant, MRI-0923389

  20. Interactions Among Water, Carbon, And Nutrient Cycles With Woody Plant Encroachment Into Grasslands

    NASA Astrophysics Data System (ADS)

    Jackson, R. B.; Engel, V.; Jobbagy, E. G.; McElrone, A. J.; Pockman, W. T.

    2003-12-01

    The expansion of woody plants into deserts, grasslands, and savannas alters water and nutrient cycling, affecting some one-fifth of the world's population. In this talk, research along precipitation gradients in North and South America will be used to examine interactions among water, carbon and nutrients in the southwestern U.S. and in grasslands of Argentina and Uruguay. Those interactions include groundwater uptake, carbon sequestration, changes in salinity and pH, and new evidence for the direct uptake of nutrients at depth using stable isotopes. The talk will end with a discussion of key unanswered research questions at the boundary of hydrology, biology, and geochemistry associated with woody plant encroachment.

  1. Woody hardness - a novel classification for the radiotherapy-treated neck.

    PubMed

    Colbert, S D; Mitchell, D A; Brennan, P A

    2015-04-01

    The term 'woody neck' is widely used by surgeons and oncologists to describe the fibrosis that can occur following radiotherapy for head and neck malignancy. These soft tissue and skin changes can be compounded by neck dissection, either before or after radiotherapy. To our knowledge, there is no classification published in the literature to describe the degree of woody hardness following treatment. We propose a simple ABC classification for varying degrees of indurated oedema and neck fibrosis secondary to radiotherapy or long-standing pathology, using the hardness of different woods to enable a suitable description to be made of severity.

  2. Assessing Extension's Ability to Promote Family Forests as a Woody Biomass Feedstock in the Northeast United States

    ERIC Educational Resources Information Center

    Germain, Rene' H.; Ghosh, Chandrani

    2013-01-01

    The study reported here surveyed Extension educators' awareness and knowledge of woody biomass energy and assessed their desire and ability to reach out to family forest owners-a critical feedstock source. The results indicate Extension educators are aware of the potential of woody biomass to serve as a renewable source of energy. Respondents…

  3. Obtaining biophysical measurements of woody vegetation from high resolution digital aerial photography in tropical and arid environments: Northern Territory, Australia

    NASA Astrophysics Data System (ADS)

    Staben, G. W.; Lucieer, A.; Evans, K. G.; Scarth, P.; Cook, G. D.

    2016-10-01

    Biophysical parameters obtained from woody vegetation are commonly measured using field based techniques which require significant investment in resources. Quantitative measurements of woody vegetation provide important information for ecological studies investigating landscape change. The fine spatial resolution of aerial photography enables identification of features such as trees and shrubs. Improvements in spatial and spectral resolution of digital aerial photographic sensors have increased the possibility of using these data in quantitative remote sensing. Obtaining biophysical measurements from aerial photography has the potential to enable it to be used as a surrogate for the collection of field data. In this study quantitative measurements obtained from digital aerial photography captured at ground sampling distance (GSD) of 15 cm (n = 50) and 30 cm (n = 52) were compared to woody biophysical parameters measured from 1 ha field plots. Supervised classification of the aerial photography using object based image analysis was used to quantify woody and non-woody vegetation components in the imagery. There was a high correlation (r ≥ 0.92) between all field measured woody canopy parameters and aerial derived green woody cover measurements, however only foliage projective cover (FPC) was found to be statistically significant (paired t-test; α = 0.01). There was no significant difference between measurements derived from imagery captured at either GSD of 15 cm and 30 cm over the same field site (n = 20). Live stand basal area (SBA) (m2 ha-1) was predicted from the aerial photographs by applying an allometric equation developed between field-measured live SBA and woody FPC. The results show that there was very little difference between live SBA predicted from FPC measured in the field or from aerial photography. The results of this study show that accurate woody biophysical parameters can be obtained from aerial photography from a range of woody vegetation

  4. Climatic regions as an indicator of forest coarse and fine woody debris carbon stocks in the United States

    PubMed Central

    Woodall, Christopher W; Liknes, Greg C

    2008-01-01

    Background Coarse and fine woody debris are substantial forest ecosystem carbon stocks; however, there is a lack of understanding how these detrital carbon stocks vary across forested landscapes. Because forest woody detritus production and decay rates may partially depend on climatic conditions, the accumulation of coarse and fine woody debris carbon stocks in forests may be correlated with climate. This study used a nationwide inventory of coarse and fine woody debris in the United States to examine how these carbon stocks vary by climatic regions and variables. Results Mean coarse and fine woody debris forest carbon stocks vary by Köppen's climatic regions across the United States. The highest carbon stocks were found in regions with cool summers while the lowest carbon stocks were found in arid desert/steppes or temperate humid regions. Coarse and fine woody debris carbon stocks were found to be positively correlated with available moisture and negatively correlated with maximum temperature. Conclusion It was concluded with only medium confidence that coarse and fine woody debris carbon stocks may be at risk of becoming net emitter of carbon under a global climate warming scenario as increases in coarse or fine woody debris production (sinks) may be more than offset by increases in forest woody detritus decay rates (emission). Given the preliminary results of this study and the rather tenuous status of coarse and fine woody debris carbon stocks as either a source or sink of CO2, further research is suggested in the areas of forest detritus decay and production. PMID:18541029

  5. Cheatgrass invasion and woody species encroachment in the Great Basin: benefits of conservation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Great Basin is the largest North American desert covering more than 122.5 million acres. Two of the biggest threats to ecosystem stability and integrity in the Great Basin are invasive annual grasses and expansion of native woody plants. The alteration of native plant communities by these invas...

  6. Phototropic bending of non-elongating and radially growing woody stems results from asymmetrical xylem formation.

    PubMed

    Matsuzaki, Jun; Masumori, Masaya; Tange, Takeshi

    2007-05-01

    Active phototropic bending of non-elongating and radially growing portion of stems (woody stems) has not been previously documented, whereas negative gravitropic bending is well known. We found phototropic bending in woody stems and searched for the underlying mechanism. We inclined 1-year-old Quercus crispula Blume seedlings and unilaterally illuminated them from a horizontal direction perpendicular to ('normal' illumination) or parallel to ('parallel' illumination) the inclination azimuth. With normal illumination, active phototropic bending and xylem formation could be evaluated separately from the negative gravitropic response and vertical deflection resulting from the weight of the seedlings. One-year-old stems with normal illumination bent significantly, with asymmetrical xylem formation towards the illuminated upper surface and side of the stem, whereas those with parallel illumination showed non-significant lateral bending, with asymmetrical xylem formation only on the upper side. A mechanical model was built on the assumption that a bending moment resulted from the asymmetrical xylem formation during phototropic bending of the woody stems. The model fitted the relationship between the observed spatial distributions of the xylem and the observed lateral bending, and thus supported the hypothesis that phototropic bending of woody stems results from asymmetrical xylem formation, as such occurs during gravitropism.

  7. Woody plant establishment in grassed reclamation areas of the Athabasca oil sands

    SciTech Connect

    Fedkenheuer, A.W.

    1980-12-01

    The primary end land use for areas disturbed by the Syncrude Canada Ltd. oil sands surface mining venture is forest cover. Short term erosion control is of concern, however, and this results in the early establishment of a grass and legume cover. Problems have subsequently been encountered in attempts to establish woody plants in the grass and legume cover. Vegetation competition for soil moisture and nutrients and rodent damage to woody seedlings have been the major problem areas. A study was initiated in 1978 to evaluate methods of manipulating the grass and legume cover sufficiently to improve success rates in establishing a variety of shrubs and trees. Five replicated treatments using the chemical herbicide glyphosate, soil scarification and fire alone plus soil scarification were established on an area seeded to grass and legumes in spring 1976. Woody plant survival and rodent damage, populations and distribution are being assessed annually in spring and fall. Rodent damage to woody seedlings was heavy in fall 1978 with 80 percent of the deciduous seedlings on non-scarified plots being damaged. In June 1979, 98 percent of the deciduous plants on the control and herbicide treatment areas were damaged. Damage to conifers was approximately 30 percent less during this time. Prescribed burning and mechanical scarification substantially reduced rodent damage. Seedling survival was variable with Amelanchier alnifolia, Pinus contorta and Populus tremuloides consistently exhibiting the highest survival rates.

  8. [Frost-resistance of subtropical evergreen woody plants: an evaluation based on plant functional traits].

    PubMed

    Xu, Yi-Lu; Yang, Xiao-Dong; Xu, Yue; Xie, Yi-Ming; Wang, Liang-Yan; Yan, En-Rong

    2012-12-01

    Evaluating the frost-resistance of evergreen woody plants is of significance in guiding the species selection in forest management in subtropical region. In this paper, an investigation was made on the functional traits (including specific leaf area, stem wood density, leaf area, leaf dry matter content, leaf relative electrical conductance, and twig wood density) of 64 common evergreen broad-leaved and coniferous woody plant species in the Ningbo region of Zhejiang Province, East China, after a severe snowstorm in early 2008, aimed to select the evergreen woody plants with high ability of freeze-tolerance, and to establish a related evaluation system. By using a hierarchy analysis approach, the weight values of the functional traits of each species were determined, and an index system for evaluating the plants tolerance ability against freeze and mechanical damage was established. Based on this system, 23 evergreen plant species with high tolerance ability against freeze and mechanical damage, such as Cyclobalanopsis gilva, Cyclobalanopsis nubium, Neolitsea aurata, and Vacciniuim mandarinorum, were selected. In the meantime, on the basis of the ordering with each of the functional traits, the ordering of the tolerance ability of the 64 plant species against freeze and mechanical damage was made, and a list for the frost-resistance ability of the subtropical evergreen woody plant species in Ningbo region was constituted.

  9. Soil carbon and nitrogen across a chronosequence of woody plant expansion in North Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Woody plant expansion has been documented on grasslands worldwide as a result of overgrazing and fire suppression, but the changes in ecosystem structure and function accompanying this phenomenon have yet to be extensively studied in the temperate semi-arid grasslands of North America. The primary o...

  10. Is Obsessive-Compulsive Disorder a Disturbance of Security Motivation? Comment on Szechtman and Woody (2004)

    ERIC Educational Resources Information Center

    Taylor, Steven; McKay, Dean; Abramowitz, Jonathan S.

    2005-01-01

    H. Szechtman and E. Woody proposed that obsessive-compulsive disorder (OCD) is caused by a malfunctioning brain security motivation system. In the current article, the authors' review of the model suggests that it is limited in the following ways: (a) It is built on a selective review of the empirical literature, (b) it offers no explanation for…

  11. Grazing effect on woody plant recruitment in a Sonoran Desert grassland across space and time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Livestock grazing is a commonly cited factor contributing to shrub encroachment in savannas and grasslands. Patterns of woody plant proliferation are known to influence rates of erosion and spread of disturbance and are of practical importance to livestock management with regard to forage distribut...

  12. A Computer-Based Multimedia Instruction Program for Woody Plant Identification.

    ERIC Educational Resources Information Center

    Seiler, J. R.; Peterson, J. A.; Taylor, C. D.; Feret, P. P.

    1997-01-01

    Discusses a multimedia-based program designed to provide students with a self-paced study of woody plants using color images of twigs, leaves, bark, fruit, and flowers. The program uses Authorware, software that can be used on both Macintosh- and Windows-compatible platforms. This program is intended for use as a supplement to field-study…

  13. Promise of combined hydrothermal/chemical and mechanical refining for pretreatment of woody and herbaceous biomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Production of advanced biofuels from woody and herbaceous feedstocks is moving into commercialization. Biomass needs to be pretreated to overcome the physicochemical properties of biomass that hinder enzyme accessibility, impeding the conversion of the plant cell walls to fermentable sugars. Pretrea...

  14. Landowners' Knowledge, Attitudes, and Aspirations towards Woody Biomass Markets in North Carolina

    ERIC Educational Resources Information Center

    Shaw, Jasmine; Hazel, Dennis; Bardon, Robert; Jayaratne, K. S. U.

    2012-01-01

    Non-industrial private forest (NIPF) landowners are often not included in discussions of emerging woody biomass markets for energy, yet they will likely be principal suppliers of the resource. Surveys administered to 475 forest landowners before and after an Extension Forestry education program in 10 counties across North Carolina indicated that…

  15. Changes to soil organic N dynamics with leguminous woody plant encroachment into grasslands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The encroachment of nitrogen-fixing trees and shrubs into grasslands and savannas occurs worldwide. In the Rio Grande Plains region of southern Texas, previous studies have shown that woody encroachment by leguminous Prosopis glandulosa (mesquite) trees increases soil and microbial biomass nitrogen ...

  16. Simulating impacts of Woody Biomass Harvesting on North Temperate Forest Carbon and Nitrogen Cycling and Storage

    NASA Astrophysics Data System (ADS)

    Hua, D.; Desai, A. R.; Bolstad, P.; Cook, B. D.; Scheller, R.

    2012-12-01

    Woody biomass harvesting is a common feature of forest management given its importance to society for acquisition of pulp and paper, lumber, and wood-based biofuel. Harvest affects many aspects of the forest environment such as biodiversity, soil nutrient quality, physical properties of soil, water quality, wildlife habitat, and climate feedbacks. In this study, we applied a modified CENTURY model to the Willow Creek, Wisconsin Ameriflux site for simulation of the impacts of woody biomass removal on forest carbon and nitrogen storage. Woody biomass harvesting scenarios with different harvesting types, interval, tree species, and soil properties were designed and tested in the model to explore the impact of harvesting on forest productivity, soil and biomass carbon and nitrogen storage, and net carbon exchange between terrestrial ecosystem and the atmosphere. Comparisons of the impacts among harvesting scenarios indicate that woody biomass harvesting significantly alters long-term net soil carbon and nitrogen storage as well as carbon exchange between terrestrial ecosystem and the atmosphere. The simulation results also provide a framework for incorporating carbon management into sustainable forest management practices.

  17. Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Woody encroachment is a globally occurring phenomenon that is thought to contribute significantly to the global carbon (C) sink. The C contribution needs to be estimated at regional and local scales to address large uncertainties present in the global- and continental-scale estimates and guide regio...

  18. A Plumber's-Eye View of Xylem Water Transport in Woody Plants

    ERIC Educational Resources Information Center

    Martinez-Vilalta, Jordi; Pinol, Josep

    2004-01-01

    We present a practical for university-level students aimed at measuring and comparing xylem hydraulic properties of co-existing plant species. After sampling branches of several woody species in the field, their main hydraulic properties were measured using a simple set-up. Hydraulic conductivity ("K[subscript h]") was calculated as the ratio…

  19. A Computer-Based Simulation for Teaching Heat Transfer across a Woody Stem

    ERIC Educational Resources Information Center

    Maixner, Michael R.; Noyd, Robert K.; Krueger, Jerome A.

    2010-01-01

    To assist student understanding of heat transfer through woody stems, we developed an instructional package that included an Excel-based, one-dimensional simulation model and a companion instructional worksheet. Guiding undergraduate botany students to applying principles of thermodynamics to plants in nature is fraught with two main obstacles:…

  20. Woody plants and the prediction of climate-change impacts on bird diversity.

    PubMed

    Kissling, W D; Field, R; Korntheuer, H; Heyder, U; Böhning-Gaese, K

    2010-07-12

    Current methods of assessing climate-induced shifts of species distributions rarely account for species interactions and usually ignore potential differences in response times of interacting taxa to climate change. Here, we used species-richness data from 1005 breeding bird and 1417 woody plant species in Kenya and employed model-averaged coefficients from regression models and median climatic forecasts assembled across 15 climate-change scenarios to predict bird species richness under climate change. Forecasts assuming an instantaneous response of woody plants and birds to climate change suggested increases in future bird species richness across most of Kenya whereas forecasts assuming strongly lagged woody plant responses to climate change indicated a reversed trend, i.e. reduced bird species richness. Uncertainties in predictions of future bird species richness were geographically structured, mainly owing to uncertainties in projected precipitation changes. We conclude that assessments of future species responses to climate change are very sensitive to current uncertainties in regional climate-change projections, and to the inclusion or not of time-lagged interacting taxa. We expect even stronger effects for more specialized plant-animal associations. Given the slow response time of woody plant distributions to climate change, current estimates of future biodiversity of many animal taxa may be both biased and too optimistic.

  1. Woody plants and the prediction of climate-change impacts on bird diversity

    PubMed Central

    Kissling, W. D.; Field, R.; Korntheuer, H.; Heyder, U.; Böhning-Gaese, K.

    2010-01-01

    Current methods of assessing climate-induced shifts of species distributions rarely account for species interactions and usually ignore potential differences in response times of interacting taxa to climate change. Here, we used species-richness data from 1005 breeding bird and 1417 woody plant species in Kenya and employed model-averaged coefficients from regression models and median climatic forecasts assembled across 15 climate-change scenarios to predict bird species richness under climate change. Forecasts assuming an instantaneous response of woody plants and birds to climate change suggested increases in future bird species richness across most of Kenya whereas forecasts assuming strongly lagged woody plant responses to climate change indicated a reversed trend, i.e. reduced bird species richness. Uncertainties in predictions of future bird species richness were geographically structured, mainly owing to uncertainties in projected precipitation changes. We conclude that assessments of future species responses to climate change are very sensitive to current uncertainties in regional climate-change projections, and to the inclusion or not of time-lagged interacting taxa. We expect even stronger effects for more specialized plant–animal associations. Given the slow response time of woody plant distributions to climate change, current estimates of future biodiversity of many animal taxa may be both biased and too optimistic. PMID:20513712

  2. Woody Debris: Denitrification Hotspots and N2O Production in Fluvial Systems

    EPA Science Inventory

    The maintenance and restoration of forested riparian cover is important for watershed nitrogen (N) cycling. Forested riparian zones provide woody debris to streams that may stimulate in-stream denitrification and control nitrous oxide (N2O) production. We examined the effects of ...

  3. Long-term livestock exclusion facilitates native woody plant encroachment in a sandy semiarid rangeland

    PubMed Central

    Su, Hua; Liu, Wei; Xu, Hong; Wang, Zongshuai; Zhang, Huifang; Hu, Haixiao; Li, Yonggeng

    2015-01-01

    The role of livestock grazing in regulating woody cover and biomass in grass-dominant systems is well recognized. However, the way in which woody plant populations in respond when livestock are removed from grazing in the absence of other disturbances, such as fire, remains unclear. We conducted a 10-year, replicated fencing experiment in a sandy semiarid rangeland in northern China (which has a mean annual rainfall of 365 mm), where fires have been actively suppressed for decades. Fencing dramatically influenced the growth and age structure of the native tree species, Ulmus pumila, which is the sole dominant tree in the area. After a decade, the density of the U. pumila tree population in the fencing plots increased doubly and canopy cover increased triply. The proportion of both saplings (U2) and young trees (U3) increased in fencing plots but decreased in grazing plots after the 10-year treatment period. The effects of fencing on U. pumila trees varied by age class, with potential implications for the future structure of the U. pumila tree community. Decadal fencing led to approximately 80-fold increase in recruitment and a nearly 2.5-fold decrease in the mortality of both U2 and U3. Further, livestock grazing generated a “browsing trap” to the recruitment of both U2 and U3, and had a small impact on the mortality of old trees. A long-term, fencing-driven shift in woody species composition was mediated via its effects on both recruitment and mortality rates. Synthesis and applications. Our results demonstrate that in the long-term absence of both fire and livestock, native woody plant encroachment tends to occur in sandy rangelands, transforming the woody plant demography in the process. The feasibility of full livestock exclusion in sandy rangelands requires further discussion. A balanced amount of livestock grazing may provide critical ecosystem services by regulating woody cover and mediating woody plant encroachment. PMID:26120433

  4. Changes in soil phosphorus fractions following woody plant invasion of grassland

    NASA Astrophysics Data System (ADS)

    Kantola, I. B.; Boutton, T. W.; Filley, T. R.; Hallmark, C. T.

    2010-12-01

    Many grass-dominated ecosystems around the world have experienced woody plant encroachment over the last century due to livestock grazing, fire suppression, and/or changes in climate and atmospheric chemistry. In the Rio Grande Plains of Texas, subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands and altered the biogeochemistry of this region. The purpose of this study was to assess the impact of this grassland-to-woodland transition on the size, distribution, and availability of soil P pools. A modified Hedley method was employed to fractionate soil P into pools based on organic and inorganic forms and relative plant-availability. Soil samples (0-10 cm) were collected in remnant grasslands and near the centers of woody plant clusters ranging in age from 14 to 86 years in a subtropical savanna parkland in southern Texas. Soil P was fractionated into resin-extractable inorganic P, bicarbonate-extractable organic and inorganic P, hydroxide-extractable organic and inorganic P, acid-extractable inorganic P, and residual inorganic P forms. P concentrations in these fractions were determined by colorimetry, and soil total P was determined by lithium fusion. Organic P was calculated from the difference between total and inorganic P. Total P in whole soils increased dramatically from 102 mg P/kg soil in remnant grasslands to 166 mg P/kg soil in the oldest woody plant stands (70-85 years). P concentrations in all pools increased linearly with increasing woody plant stand age except acid-extractable phosphorus. The most dramatic increases were observed in the resin-extractable fraction (plant-available P), which increased from 3 to 13 mg P/kg soil, and in hydroxide-extractable P (the majority of the organic P in the system), which increased from 15 mg P/kg soil in grasslands to 26 mg P/kg soil in the wooded clusters. Although the exact mechanisms by which soil P increases following woody invasion remain unknown, we suggest that the

  5. Changes in Soil Phosphorus Fractions Following Woody Plant Invasion of Grassland

    NASA Astrophysics Data System (ADS)

    Boutton, T. W.; Kantola, I. B.; Filley, T. R.

    2012-12-01

    Many grass-dominated ecosystems around the world have experienced woody plant encroachment over the last century due to livestock grazing, fire suppression, and/or changes in climate and atmospheric chemistry. In the Rio Grande Plains of Texas, subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands and altered the biogeochemistry of this region. The purpose of this study was to assess the impact of this grassland-to-woodland transition on the size, distribution, and availability of soil P pools. A modified Hedley method was employed to fractionate soil P into pools based on organic and inorganic forms and relative plant-availability. Soil samples (0-10 cm) were collected in remnant grasslands and near the centers of woody plant clusters ranging in age from 14 to 86 yrs in a subtropical savanna parkland in southern Texas. Soil P was fractionated into resin-extractable inorganic P, bicarbonate-extractable organic and inorganic P, hydroxide-extractable organic and inorganic P, acid-extractable inorganic P, and residual inorganic P forms. P concentrations in these fractions were determined by colorimetry, and soil total P was determined by lithium fusion. Organic P was calculated from the difference between total and inorganic P. Total P in whole soils increased dramatically from 98 mg P kg-1 soil in remnant grasslands to 168 mg P kg-1 soil in the oldest woody plant stands (70-85 yrs). P concentrations in all pools increased linearly with increasing woody plant stand age except acid-extractable phosphorus. The most dramatic increases were observed in the resin-extractable fraction (plant-available P), which increased from 3 to 13 mg P kg-1 soil, and in hydroxide-extractable P (the majority of the organic P in the system), which increased from 15 mg P kg-1 soil in grasslands to 26 mg P kg-1 soil in the wooded clusters. Although the exact mechanisms by which soil P increases following woody invasion remain unknown, we suggest that

  6. Long-term livestock exclusion facilitates native woody plant encroachment in a sandy semiarid rangeland.

    PubMed

    Su, Hua; Liu, Wei; Xu, Hong; Wang, Zongshuai; Zhang, Huifang; Hu, Haixiao; Li, Yonggeng

    2015-06-01

    The role of livestock grazing in regulating woody cover and biomass in grass-dominant systems is well recognized. However, the way in which woody plant populations in respond when livestock are removed from grazing in the absence of other disturbances, such as fire, remains unclear.We conducted a 10-year, replicated fencing experiment in a sandy semiarid rangeland in northern China (which has a mean annual rainfall of 365 mm), where fires have been actively suppressed for decades.Fencing dramatically influenced the growth and age structure of the native tree species, Ulmus pumila, which is the sole dominant tree in the area. After a decade, the density of the U. pumila tree population in the fencing plots increased doubly and canopy cover increased triply. The proportion of both saplings (U 2 ) and young trees (U 3 ) increased in fencing plots but decreased in grazing plots after the 10-year treatment period. The effects of fencing on U. pumila trees varied by age class, with potential implications for the future structure of the U. pumila tree community. Decadal fencing led to approximately 80-fold increase in recruitment and a nearly 2.5-fold decrease in the mortality of both U 2 and U 3 . Further, livestock grazing generated a "browsing trap" to the recruitment of both U 2 and U 3 , and had a small impact on the mortality of old trees. A long-term, fencing-driven shift in woody species composition was mediated via its effects on both recruitment and mortality rates.Synthesis and applications. Our results demonstrate that in the long-term absence of both fire and livestock, native woody plant encroachment tends to occur in sandy rangelands, transforming the woody plant demography in the process. The feasibility of full livestock exclusion in sandy rangelands requires further discussion. A balanced amount of livestock grazing may provide critical ecosystem services by regulating woody cover and mediating woody plant encroachment.

  7. Carbon Exchange and Water Use in Karst Landscapes: Impact of Woody Encroachment

    NASA Astrophysics Data System (ADS)

    Heilman, J. L.; Litvak, M. E.

    2008-05-01

    Woody plant invasion into grasslands and savannas, and its impact on water use are critical issues in karst landscapes because 25% of the world's population obtains its water from karst aquifers. It is well documented that woody encroachment increases carbon sequestration, but its impact on water use is less clear. It is widely presumed that woody plants increase evapotranspiration (ET), in part because deep root systems provide access to a more stable supply of water than what is available to grasses. If this is true, woody encroachment should reduce the sensitivity of carbon exchange and ET to rainfall pulses and water deficits, and vulnerability to drought. Since 2004, we have been investigating, via eddy covariance, carbon exchange and water use on a grassland, a savanna with approximately 35% woody cover, and a dense live oak-Ashe juniper forest on the karst Edwards Plateau in south and west central Texas. The Plateau is a 93,000 km2 karst ecoregion that is dominated by live oak-Ashe juniper savannas underlain by mixed C3/C4 grasses, and soils are generally shallow. The Plateau contains the Edwards Aquifer which supplies drinking water to over 2 million people, and is home to a number of threatened and endangered species, many of them aquatic. Populations of juniper are expanding due to suppression of wildfires, and public funds are being spent to remove juniper in an attempt to increase water availability. Our measurements show large differences in carbon sequestration among the ecosystems (highest in savanna and lowest in grassland), and small differences in ET (~0.2 mm day-1 higher in the forest than in the grassland). We attribute increased ET to increases in net radiation, and proportionally greater partitioning of available energy into sensible heat flux at the expense of latent heat flux. We found little differences in response of carbon exchange and ET to rainfall and water deficits, regardless of the amount of woody cover, intensity of rainfall, or

  8. Woody-to-total area ratio determination with a multispectral canopy imager.

    PubMed

    Zou, Jie; Yan, Guangjian; Zhu, Ling; Zhang, Wuming

    2009-08-01

    Leaf area index (LAI) - defined as one half of the total green leaf area per unit ground surface area - can be determined by direct or indirect methods. Three major sources of errors exist in indirect LAI measurements: within-shoot clumping, beyond-shoot clumping and non-photosynthetic components. The effect of non-photosynthetic components on LAI measurements can be described by the woody-to-total area ratio, alpha; however, no convenient and efficient indirect methods have been developed to estimate alpha, especially the variations in alpha with zenith angle , alpha(theta). We describe the development and use of a multispectral canopy imager (MCI) to estimate alpha and alpha(theta) by considering the effects of non-random distributions of canopy elements and woody components and the overestimation of needle-to-shoot area ratio on woody components. The MCI, which mainly comprises a near-infrared band camera (Fujifilm IS-1), two visible band cameras (Canon 40D), filters and a pan tilt, was developed to measure clumping index, woody-to-total area ratio and geometric parameters of isolated trees. Two typical sampling plots (Plots 1 and 5) chosen from among 16 permanent forest experiment plots were selected for the estimation of alpha and alpha(theta). The non-random distributions of canopy elements and woody components were estimated separately at eight zenith angles (from 0 degrees to 70 degrees in increments of 10 degrees) using MCI images based on the gap size distribution theory. The visible/near-infrared image pairs captured by the MCI were able to discriminate among sky, leaves, cloud and woody components. Based on three methods of estimation, we obtained woody-to-total area ratios of 0.24, 0.19, 0.19 for Plot 1 and 0.23, 0.18, 0.17 for Plot 5. If clumping effects were ignored, alpha values were overestimated by as much as 21% and 24% at Plots 1 and 5, respectively. We demonstrated that alpha(theta) varied with the zenith angle, with variations in the range of

  9. Effects of woody encroachment on savanna nitrogen dynamics: Combining biogeochemistry and remote sensing

    NASA Astrophysics Data System (ADS)

    Martin, Roberta Enders

    Woody encroachment, the increase of woody plant density relative to herbaceous vegetation, has contributed to documented biophysical and biogeochemical changes world-wide, and locally in the southwestern U.S. In North Texas rangelands, encroaching mesquite (Prosopis glandulosa var. glandulosa ), a known nitrogen (N)-fixing species, has caused changes in aboveground biomass. However, the impacts of woody encroachment on N cycling have not been well studied, despite the central role that N dynamics play in controlling carbon (C) cycling and many other ecological processes across all spatial scales from microbial soil processes to global plant productivity. Airborne remote sensing is arguably the only approach available to develop a spatially-explicit understanding of ecosystem processes. The main goal of this research was to determine whether remotely sensible parameters of vegetation structure could be used to quantify biogeochemical changes in N at the local, landscape and regional scale. To accomplish this goal, I first characterized the impact of woody encroachment on soil nitrogen oxide (nitric-NO and nitrous-N2O oxide) emissions. I examined biotic (vegetation type and soil organic and inorganic N dynamics) and abiotic (soil moisture, temperature, and soil texture) controls over soil NO and N2O emissions across a gradient of aboveground (AG) Prosopis biomass growing on two soil types. I concluded that mesquite encroachment in these grasslands increased NO emissions in a spatially explicit manner influenced by the AG biomass and soil type, which was then temporally mediated by temperature and secondarily by precipitation. Based on these results, I combined hyperspectral remote sensing and field measurements to quantify spatial patterns and to estimate regional fluxes of soil NO emissions across 120 km2 of semi-arid rangeland in North Texas. This analysis captured the high spatial variability of NO emissions as they co-varied with vegetation cover and soil type

  10. Evaluating nurse plants for restoring native woody species to degraded subtropical woodlands

    PubMed Central

    Yelenik, Stephanie G; DiManno, Nicole; D'Antonio, Carla M

    2015-01-01

    Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of “nurse plants” an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native (Dodonaea viscosa, Leptocophylla tameiameia) and one non-native (Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability. PMID:25709807

  11. Evaluating nurse plants for restoring native woody species to degraded subtropical woodlands

    USGS Publications Warehouse

    Yelenik, Stephanie G.; DiManno, Nicole; D’Antonio, Carla M.

    2015-01-01

    Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of “nurse plants” an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native (Dodonaea viscosa, Leptocophylla tameiameia) and one non-native (Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability.

  12. Effects of topoclimatic complexity on the composition of woody plant communities.

    PubMed

    Oldfather, Meagan F; Britton, Matthew N; Papper, Prahlad D; Koontz, Michael J; Halbur, Michelle M; Dodge, Celeste; Flint, Alan L; Flint, Lorriane E; Ackerly, David D

    2016-01-01

    Topography can create substantial environmental variation at fine spatial scales. Shaped by slope, aspect, hill-position and elevation, topoclimate heterogeneity may increase ecological diversity, and act as a spatial buffer for vegetation responding to climate change. Strong links have been observed between climate heterogeneity and species diversity at broader scales, but the importance of topoclimate for woody vegetation across small spatial extents merits closer examination. We established woody vegetation monitoring plots in mixed evergreen-deciduous woodlands that spanned topoclimate gradients of a topographically heterogeneous landscape in northern California. We investigated the association between the structure of adult and regenerating size classes of woody vegetation and multidimensional topoclimate at a fine scale. We found a significant effect of topoclimate on both single-species distributions and community composition. Effects of topoclimate were evident in the regenerating size class for all dominant species (four Quercus spp., Umbellularia californica and Pseudotsuga menziesii) but only in two dominant species (Quercus agrifolia and Quercus garryana) for the adult size class. Adult abundance was correlated with water balance parameters (e.g. climatic water deficit) and recruit abundance was correlated with an interaction between the topoclimate parameters and conspecific adult abundance (likely reflecting local seed dispersal). However, in all cases, the topoclimate signal was weak. The magnitude of environmental variation across our study site may be small relative to the tolerance of long-lived woody species. Dispersal limitations, management practices and patchy disturbance regimes also may interact with topoclimate, weakening its influence on woody vegetation distributions. Our study supports the biological relevance of multidimensional topoclimate for mixed woodland communities, but highlights that this relationship might be mediated by

  13. Effects of topoclimatic complexity on the composition of woody plant communities

    PubMed Central

    Oldfather, Meagan F.; Britton, Matthew N.; Papper, Prahlad D.; Koontz, Michael J.; Halbur, Michelle M.; Dodge, Celeste; Flint, Alan L.; Flint, Lorriane E.; Ackerly, David D.

    2016-01-01

    Topography can create substantial environmental variation at fine spatial scales. Shaped by slope, aspect, hill-position and elevation, topoclimate heterogeneity may increase ecological diversity, and act as a spatial buffer for vegetation responding to climate change. Strong links have been observed between climate heterogeneity and species diversity at broader scales, but the importance of topoclimate for woody vegetation across small spatial extents merits closer examination. We established woody vegetation monitoring plots in mixed evergreen-deciduous woodlands that spanned topoclimate gradients of a topographically heterogeneous landscape in northern California. We investigated the association between the structure of adult and regenerating size classes of woody vegetation and multidimensional topoclimate at a fine scale. We found a significant effect of topoclimate on both single-species distributions and community composition. Effects of topoclimate were evident in the regenerating size class for all dominant species (four Quercus spp., Umbellularia californica and Pseudotsuga menziesii) but only in two dominant species (Quercus agrifolia and Quercus garryana) for the adult size class. Adult abundance was correlated with water balance parameters (e.g. climatic water deficit) and recruit abundance was correlated with an interaction between the topoclimate parameters and conspecific adult abundance (likely reflecting local seed dispersal). However, in all cases, the topoclimate signal was weak. The magnitude of environmental variation across our study site may be small relative to the tolerance of long-lived woody species. Dispersal limitations, management practices and patchy disturbance regimes also may interact with topoclimate, weakening its influence on woody vegetation distributions. Our study supports the biological relevance of multidimensional topoclimate for mixed woodland communities, but highlights that this relationship might be mediated by

  14. Forest structure and downed woody debris in boreal, temperate, and tropical forest fragments.

    PubMed

    Gould, William A; González, Grizelle; Hudak, Andrew T; Hollingsworth, Teresa Nettleton; Hollingsworth, Jamie

    2008-12-01

    Forest fragmentation affects the heterogeneity of accumulated fuels by increasing the diversity of forest types and by increasing forest edges. This heterogeneity has implications in how we manage fuels, fire, and forests. Understanding the relative importance of fragmentation on woody biomass within a single climatic regime, and along climatic gradients, will improve our ability to manage forest fuels and predict fire behavior. In this study we assessed forest fuel characteristics in stands of differing moisture, i.e., dry and moist forests, structure, i.e., open canopy (typically younger) vs. closed canopy (typically older) stands, and size, i.e., small (10-14 ha), medium (33 to 60 ha), and large (100-240 ha) along a climatic gradient of boreal, temperate, and tropical forests. We measured duff, litter, fine and coarse woody debris, standing dead, and live biomass in a series of plots along a transect from outside the forest edge to the fragment interior. The goal was to determine how forest structure and fuel characteristics varied along this transect and whether this variation differed with temperature, moisture, structure, and fragment size. We found nonlinear relationships of coarse woody debris, fine woody debris, standing dead and live tree biomass with mean annual median temperature. Biomass for these variables was greatest in temperate sites. Forest floor fuels (duff and litter) had a linear relationship with temperature and biomass was greatest in boreal sites. In a five-way multivariate analysis of variance we found that temperature, moisture, and age/structure had significant effects on forest floor fuels, downed woody debris, and live tree biomass. Fragment size had an effect on forest floor fuels and live tree biomass. Distance from forest edge had significant effects for only a few subgroups sampled. With some exceptions edges were not distinguishable from interiors in terms of fuels.

  15. Evaluating nurse plants for restoring native woody species to degraded subtropical woodlands.

    PubMed

    Yelenik, Stephanie G; DiManno, Nicole; D'Antonio, Carla M

    2015-01-01

    Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of "nurse plants" an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native (Dodonaea viscosa, Leptocophylla tameiameia) and one non-native (Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability.

  16. A model of the extent and distribution of woody linear features in rural Great Britain.

    PubMed

    Scholefield, Paul; Morton, Dan; Rowland, Clare; Henrys, Peter; Howard, David; Norton, Lisa

    2016-12-01

    Hedges and lines of trees (woody linear features) are important boundaries that connect and enclose habitats, buffer the effects of land management, and enhance biodiversity in increasingly impoverished landscapes. Despite their acknowledged importance in the wider countryside, they are usually not considered in models of landscape function due to their linear nature and the difficulties of acquiring relevant data about their character, extent, and location. We present a model which uses national datasets to describe the distribution of woody linear features along boundaries in Great Britain. The method can be applied for other boundary types and in other locations around the world across a range of spatial scales where different types of linear feature can be separated using characteristics such as height or width. Satellite-derived Land Cover Map 2007 (LCM2007) provided the spatial framework for locating linear features and was used to screen out areas unsuitable for their occurrence, that is, offshore, urban, and forest areas. Similarly, Ordnance Survey Land-Form PANORAMA®, a digital terrain model, was used to screen out where they do not occur. The presence of woody linear features on boundaries was modelled using attributes from a canopy height dataset obtained by subtracting a digital terrain map (DTM) from a digital surface model (DSM). The performance of the model was evaluated against existing woody linear feature data in Countryside Survey across a range of scales. The results indicate that, despite some underestimation, this simple approach may provide valuable information on the extents and locations of woody linear features in the countryside at both local and national scales.

  17. Large woody debris and flow resistance in step-pool channels, Cascade Range, Washington

    USGS Publications Warehouse

    Curran, Janet H.; Wohl, Ellen E.

    2003-01-01

    Total flow resistance, measured as Darcy-Weisbach f, in 20 step-pool channels with large woody debris (LWD) in Washington, ranged from 5 to 380 during summer low flows. Step risers in the study streams consist of either (1) large and relatively immobile woody debris, bedrock, or roots that form fixed, or “forced,” steps, or (2) smaller and relatively mobile wood or clasts, or a mixture of both, arranged across the channel by the stream. Flow resistance in step-pool channels may be partitioned into grain, form, and spill resistance. Grain resistance is calculated as a function of particle size, and form resistance is calculated as large woody debris drag. Combined, grain and form resistance account for less than 10% of the total flow resistance. We initially assumed that the substantial remaining portion is spill resistance attributable to steps. However, measured step characteristics could not explain between-reach variations in flow resistance. This suggests that other factors may be significant; the coefficient of variation of the hydraulic radius explained 43% of the variation in friction factors between streams, for example. Large woody debris generates form resistance on step treads and spill resistance at step risers. Because the form resistance of step-pool channels is relatively minor compared to spill resistance and because wood in steps accentuates spill resistance by increasing step height, we suggest that wood in step risers influences channel hydraulics more than wood elsewhere in the channel. Hence, the distribution and function, not just abundance, of large woody debris is critical in steep, step-pool channels.

  18. Perspectives on Screening Winter-Flood-Tolerant Woody Species in the Riparian Protection Forests of the Three Gorges Reservoir

    PubMed Central

    Yang, Fan; Wang, Yong; Chan, Zhulong

    2014-01-01

    The establishment of riparian protection forests in the Three Gorges Reservoir (TGR) is an ideal measure to cope with the eco-environmental problems of the water-level fluctuation zone (WLFZ). Thus, the information for screening winter-flood-tolerant woody plant species is useful for the recovery and re-establishment of the riparian protection forests in the TGR WLFZ. Therefore, we discussed the possibilities of constructing and popularizing riparian protection forests in the TGR WLFZ from several aspects, including the woody plant species distribution in the WLFZ, the survival rate analyses of suitable candidate woody species under controlled flooding conditions, the survival rate investigation of some woody plant species planted in the TGR WLFZ, and the physiological responses of some woody plant species during the recovery stage after winter floods. The results of woody species investigation showed that most woody plant species that existed as annual seedlings in the TGR WLFZ are not suitable candidates for the riparian protection forests. However, arbor species (e.g., Salix matsudana, Populus×canadensis, Morus alba, Pterocarya stenoptera, Taxodium ascendens, and Metasequoia glyptostroboides) and shrub species (e.g., Salix variegata, Distylium chinensis, Lycium chinense, Myricaria laxiflora, and Rosa multiflora) might be considered suitable candidates for the riparian protection forests in the TGR WLFZ by survival rate analyses under controlled winter flooding conditions, and survival rate investigations of woody plant species planted in the TGR WLFZ, respectively. Physiological analyses showed that P.×canadensis, M. alba, L. chinense, and S. variegata could develop specific self-repairing mechanisms to stimulate biomass accumulation and carbohydrate synthesis via the increases in chlorophyll pigments and photosynthesis during recovery after winter floods. Our results suggested these woody plant species could endure the winter flooding stress and recover well

  19. Perspectives on screening winter-flood-tolerant woody species in the riparian protection forests of the three gorges reservoir.

    PubMed

    Yang, Fan; Wang, Yong; Chan, Zhulong

    2014-01-01

    The establishment of riparian protection forests in the Three Gorges Reservoir (TGR) is an ideal measure to cope with the eco-environmental problems of the water-level fluctuation zone (WLFZ). Thus, the information for screening winter-flood-tolerant woody plant species is useful for the recovery and re-establishment of the riparian protection forests in the TGR WLFZ. Therefore, we discussed the possibilities of constructing and popularizing riparian protection forests in the TGR WLFZ from several aspects, including the woody plant species distribution in the WLFZ, the survival rate analyses of suitable candidate woody species under controlled flooding conditions, the survival rate investigation of some woody plant species planted in the TGR WLFZ, and the physiological responses of some woody plant species during the recovery stage after winter floods. The results of woody species investigation showed that most woody plant species that existed as annual seedlings in the TGR WLFZ are not suitable candidates for the riparian protection forests. However, arbor species (e.g., Salix matsudana, Populus×canadensis, Morus alba, Pterocarya stenoptera, Taxodium ascendens, and Metasequoia glyptostroboides) and shrub species (e.g., Salix variegata, Distylium chinensis, Lycium chinense, Myricaria laxiflora, and Rosa multiflora) might be considered suitable candidates for the riparian protection forests in the TGR WLFZ by survival rate analyses under controlled winter flooding conditions, and survival rate investigations of woody plant species planted in the TGR WLFZ, respectively. Physiological analyses showed that P.×canadensis, M. alba, L. chinense, and S. variegata could develop specific self-repairing mechanisms to stimulate biomass accumulation and carbohydrate synthesis via the increases in chlorophyll pigments and photosynthesis during recovery after winter floods. Our results suggested these woody plant species could endure the winter flooding stress and recover well

  20. Competitive interactions between established grasses and woody plant seedlings under elevated CO₂ levels are mediated by soil water availability.

    PubMed

    Manea, A; Leishman, M R

    2015-02-01

    The expansion of woody plants into grasslands has been observed worldwide and is likely to have widespread ecological consequences. One proposal is that woody plant expansion into grasslands is driven in part by the rise in atmospheric CO2 concentrations. We have examined the effect of CO2 concentration on the competitive interactions between established C4 grasses and woody plant seedlings in a model grassland system. Woody plant seedlings were grown in mesocosms together with established C4 grasses in three competition treatments (root competition, shoot competition and root + shoot competition) under ambient and elevated CO2 levels. We found that the growth of the woody plant seedlings was suppressed by competition from grasses, with root and shoot competition having similar competitive effects on growth. In contrast to expectations, woody plant seedling growth was reduced at elevated CO2 levels compared to that at the ambient CO2 level across all competition treatments, with the most plausible explanation being reduced light and soil water availability in the elevated CO2 mesocosms. Reduced light and soil water availability in the elevated CO2 mesocosms was associated with an increased leaf area index of the grasses which offset the reductions in stomatal conductance and increased rainfall interception. The woody plant seedlings also had reduced 'escapability' (stem biomass and stem height) under elevated compared to ambient CO2 levels. Our results suggest that the expansion of woody plants into grasslands in the future will likely be context-dependent, with the establishment success of woody plant seedlings being strongly coupled to the CO2 response of competing grasses and to soil water availability.

  1. Woody fuels reduction in Wyoming big sagebrush communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) ecosystems historically have been subject to disturbances that reduce or remove shrubs primarily by fire, although insect outbreaks and disease have also been important. Depending on site productivity, fire return in...

  2. Controls on microbial accessibility to soil organic carbon following woody plant encroachment into grasslands

    NASA Astrophysics Data System (ADS)

    Creamer, Courtney; Boutton, Thomas; Olk, Dan; Filley, Timothy

    2010-05-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic carbon (SOC) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and hydrology. To elucidate the controls on microbial accessibility to SOC, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas Agrilife La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, and plant biopolymer chemistry in SOC were tracked. Respiration rates declined exponentially over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total SOC was mineralized to CO2 throughout the incubation. After day 84 a significantly (p<0.05) greater portion of SOC was mineralized from soils of older woody clusters (34-86 years) than from soils of younger woody clusters (14-23 years) and the native grassland. Invading woody stands of ≃≥35 years of age represent a transition point in WPE where respiration dynamics become distinct in wooded elements compared to grasslands; this distinction has been previously observed through changes in belowground SOC accrual, C input chemistry, and mycorrhizal productivity. Despite documented SOC accrual following WPE at La Copita, we observed no evidence of enhanced SOC stabilization in these respiration experiments. In fact, a greater proportion of total SOC was lost from the soil of mature woody stands than from young stands, suggesting SOC accumulation observed with WPE may be due to greater input rates or microbial dynamics not captured in the laboratory incubation. Compound-specific analyses indicated there was a significant (p<0.05) loss of C from carbohydrates, amino acids, and amino sugars during the incubation. Amino nitrogen tended to become more concentrated during the incubation, although the trend was not significant. Relatively

  3. Woody plant encroachment effect on soil organic carbon dynamics: results from a latitudinal gradient in Italy

    NASA Astrophysics Data System (ADS)

    Pellis, Guido; Chiti, Tommaso; Moscatelli, Maria Cristina; Marinari, Sara; Papale, Dario

    2016-04-01

    Woody plant encroachment into pastures and grasslands represents a significant land cover change phenomenon, with a considerable impact on carbon dynamics at an ecosystem level. It was estimated that 7.64% of the Southern Europe land was subject to that process between 1950 to 2010. As a result of woody encroachment, changes in vegetation composition can produce substantial changes to the soil organic carbon (SOC) cycle. Despite the numerous papers published on land-use change, an evaluation of the IPCC terrestrial carbon pools changes occurring during woody encroachment on abandoned pastures and grasslands is still lacking, particularly for the Italian territory. Therefore, the aim of this study was to investigate the role of woody encroachment on carbon sequestration over abandoned pastures and grasslands in Alpine and Apennine ecosystems, with a particular focus on the SOC. We applied a chronosequence approach to seven selected sites located along a latitudinal gradient in Italy. Each chronosequence consisted of a pasture currently managed, three sites abandoned at different times in the past and, finally, a mature forest stand representing the last phase of the succession. The European Commission sampling protocols to certify SOC changes was adopted to estimate the variations following woody encroachment. Soil samples were collected at different depths in the topsoil (0-30 cm) and subsoil (30-70 cm), despite the original protocol formulation being limited to the topsoil only. In addition, aboveground living biomass (AGB), dead wood and litter were also measured following international protocols. Considering all C pools together, woody plant encroachment leads to a progressive C stock accumulation in all the chronosequences. The total C stock of mature forest stands ranges from 1.78±0.11 times (Eastern Alps) to 2.48±0.31 times (central Apennine) the initial value on pastures. Unsurprisingly, the C stocks of AGB, dead wood and litter all increase during the

  4. Development and Deployment of a Short Rotation Woody Crops Harvesting System Based on a Case New Holland Forage Harvester and SRC Woody Crop Header

    SciTech Connect

    Eisenbies, Mark; Volk, Timothy; Abrahamson, Lawrence; Shuren, Richard; Stanton, Brian; Posselius, John; McArdle, Matt; Karapetyan, Samvel; Patel, Aayushi; Shi, Shun; Zerpa, Jose

    2014-10-03

    Biomass for biofuels, bioproducts and bioenergy can be sourced from forests, agricultural crops, various residue streams, and dedicated woody or herbaceous crops. Short rotation woody crops (SRWC), like willow and hybrid poplar, are perennial cropping systems that produce a number of environmental and economic development benefits in addition to being a renewable source of biomass that can be produced on marginal land. Both hybrid poplar and willow have several characteristics that make them an ideal feedstock for biofuels, bioproducts, and bioenergy; these include high yields that can be obtained in three to four years, ease of cultivar propagation from dormant cuttings, a broad underutilized genetic base, ease of breeding, ability to resprout after multiple harvests, and feedstock composition similar to other sources of woody biomass. Despite the range of benefits associated with SRWC systems, their deployment has been restricted by high costs, low market acceptance associated with inconsistent chip quality (see below for further explanation), and misperceptions about other feedstock characteristics (see below for further explanation). Harvesting of SRWC is the largest single cost factor (~1/3 of the final delivered cost) in the feedstock supply system. Harvesting is also the second largest input of primary fossil energy in the system after commercial N fertilizer, accounting for about one third of the input. Therefore, improving the efficiency of the harvesting system has the potential to reduce both cost and environmental impact. At the start of this project, we projected that improving the overall efficiency of the harvesting system by 25% would reduce the delivered cost of SRWC by approximately $0.50/MMBtu (or about $7.50/dry ton). This goal was exceeded over the duration of this project, as noted below.

  5. Activities of Extracellular Enzymes in Soils Following Woody Plant Invasion of Grassland

    NASA Astrophysics Data System (ADS)

    Filley, T. R.; Stott, D. E.; Dooling, V.; Sorg, L.; Boutton, T.

    2008-12-01

    Extracellular enzymes produced by microbes and immobilize in the soil environment are the principle means by which complex plant and microbial compounds are degraded. The concentration of these enzymes and their ability to interact with litter and soil organic matter contributes both to the stabilization and destabilization of soil carbon. We quantified the activities of three extracellular enzymes, B-glucosidase, B- glucosaminidase, polyphenol oxidase (PPO), and a general marker for hydrolytic activity through fluorescein diacetate (FDA) hydrolysis activity, in a subtropical savanna parkland in southern Texas where woody plants have invaded a once open grassland. Previous research has demonstrated that areas which have shifted to woody vegetation are accruing soil carbon, undergoing a dramatic shift in the chemistry of plant input, and increasing in hyphal biomass. Soils were obtained along a successional chronosequence from grassland dominated by C4 grasses to woody patches dominated by C3 trees/shrubs in Oct 2006 and stored immediately frozen until thawing for enzyme assay. Most enzymes, with the exception of PPO, show distinct behavior when comparing grassland and clusters in that grasslands exhibit far lower mass normalized activity than clusters and no activity trend with respect to age of the adjacent cluster. Both FDA and B- glucosaminidase activities are positively correlated with the age of the woody clusters and increase their activity by as much as 10-fold across the age gradient from 14 yr to 86 yr old clusters. The cellulose degrading enzyme, B-glucosidase, always exhibited greater activity (1.5 -4 fold) in woody clusters than in grasslands, but did not exhibit a trend with increasing cluster age. The PPO activity is anomalous in that there is no quantitative difference in mass normalized activity between grassland and cluster and no trend with cluster age. The results for the FDA and B-glucosaminidase assays are consistent with concurrent studies

  6. Size of coarse woody debris 5 years after girdling and removal treatments in 50-year-old Loblolly PIne Plantations

    SciTech Connect

    Edwards, M. Boyd

    2004-01-01

    PP 108 -113 in: Connor, Kristina F., ed. 2004. Proceedings of the 12th biennial southern silvicultural research conference. Gen. Tech. Rep. SRS71. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 594 p. Abstract: In 1996, a study began at Savannah River Site to investigate large-scale replicated forest areas to control coarse woody debris for integrated biodiversity objectives. Research design was a randomized complete block with four treatments replicated in four blocks, resulting in 16 plots. The treatments applied to 50-year-old loblolly pine stands were (1) control, (2) girdling of 25 percent of trees to create catastrophic simulation, (3) annual removal of down woody debris > 10 cm in diameter, and (4) annual removal of both standing and down woody debris > 10 cm in diameter. The study tracks coarse woody debris recruitment and loading, rates of decomposition, and effects on the forest ecosystem.

  7. Cross-stratified Wood: Enigmatic Woody Debris Deposits in Warm-Polar Fluvial Sediments (Pliocene Beaufort Formation, Nunavut)

    NASA Astrophysics Data System (ADS)

    Davies, N. S.; Gosse, J. C.; Rybczynski, N.

    2012-04-01

    Woody debris has been an important sediment component and a significant geomorphic agent in pristine fluvial systems since the Devonian. In recent years a large volume of research has focussed on various aspects of the importance of woody debris within the fluvial realm; from the evolutionary significance of fossil wood accumulations in the rock record to studies of the biogeomorphological and ecological importance of woody debris in modern rivers. In this presentation we describe cross-stratified woody debris deposits comprising organic detritus from a boreal-type treeline forest that included species of pine, birch, poplar, alder, spruce, eastern cedar, and larch, in both shrub and tree form. The cross-stratified wood is an enigmatic subset of fine woody debris which, to our knowledge, has never before been described from either the global stratigraphic record or modern fluvial environments. The deposits we describe are located within the Pliocene Beaufort Formation on Meighen Island, Nunavut, Canada, at a latitude of 80°N, and are compared with other cross-stratified woody debris deposits that have been noted elsewhere in the Pliocene of the Canadian Arctic. We make the robust observation that these deposits appear to be geographically and stratigraphically restricted to polar latitudes from a period of warm climatic conditions during the Pliocene (15-20 °C warmer mean annual temperature than the present day). In this regard it is possible to speculate that the transport of large amounts of woody debris as bedload is potentially a unique feature of forested high latitude rivers. Such bedload deposition requires a large amount of woody debris with a greater density than the fluid transporting it. The softwood composition of the debris suggests that this was most likely attained by saturation and subsequent entrainment of extensive accumulations of deadwood, promoted by unusually high rates of tree mortality and low rates of bacterial decomposition arising from

  8. Effect of long-term understory prescribed burning on standing and down dead woody material in dry upland oak forests

    USGS Publications Warehouse

    Polo, John A.; Hallgren, S.W.; Leslie,, David M.

    2013-01-01

    Dead woody material, long ignored or viewed as a nuisance for forest management, has gained appreciation for its many roles in the forest including wildlife habitat, nutrient storage and cycling, energy for trophic webs, protection of soil, fuel for fire and carbon storage. The growing interest in managing dead woody material has created strong demand for greater understanding of factors controlling amounts and turnover. Prescribed burning, an important management tool, may have strong effects of dead woody material given fire’s capacity to create and consume dead woody material. We determined effects of long-term understory prescribed burning on standing and down woody material in upland oak forests in south-central North America. We hypothesized that as frequency of fire increased in these stands the amount of deadwood would decrease and the fine woody material would decrease more rapidly than coarse woody material. The study was conducted in forests dominated by post oak (Quercus stellata) and blackjack oak (Quercus marilandica) in wildlife management areas where understory prescribed burning had been practiced for over 20 years and the range of burn frequencies was 0 (unburned) fires per decade (FPD) to 4.6 FPD. The amount of deadwood was low compared with more productive forests in southeastern North America. The biomass (24.7 Mg ha-1) and carbon stocks (11.7 Mg ha-1) were distributed among standing dead (22%), coarse woody debris (CWD, dia. > 7.5 cm., 12%), fine woody debris (FWD, dia. < 7.5 cm., 23%), and forest floor (43%). There was no evidence that understory prescribed burning influenced the amount and size distribution of standing and down dead woody material. There were two explanations for the lack of a detectable effect. First, a high incidence of severe weather including ice storms and strong winds that produce large amounts of deadwood intermittently in an irregular pattern across the landscape may preclude detecting a strong effect of understory

  9. Effects of Experimental Manipulations of Course Woody Debris on Sorcids and Other Fauna

    SciTech Connect

    McCay, T.S.; Komoroski, M.J.; Ford, W.M.; Laerm, J.; Reitz, E.J.

    2001-06-10

    The authors studied the relationship between the level of course woody debris in experimental plots of mature loblolly pine and the richness and abundance of shrews, reptiles and amphibians. Comparisons were made between plots in which all down and standing debris were removed and plots that were not treated. Removal of woody debris resulted in a week treatment effect. The capture of southeastern shrews declined through the period perhaps due to drought. The least common shrew demonstrated the strongest effects from removal.In sampling 37 species of amphibians were observed. The Carolina anole and the red salamander were captured more frequently on removal plots. No difference were found between removal and controls with regard to reptiles.

  10. Downed dead woody fuel and biomass in the Northern Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Brown, J. K.; See, T. E.

    1981-07-01

    Weights and volumes of downed woody material in diameter classes of one-fourth to 1, 1 to 3, and greater than 3 inches and forest floor duff depths were summarized from extensive inventories in nothern Idaho and Montana. Biomass loadings are shown by cover types and habitat types within National Forests. Total downed woody biomass ranged from 5 tons per acre in ponderosa pine to 33 tons per acre in cedar-hemlock. Loadings generally increased with increased productivity, but varied greatly with stand age. Fuels tended to become predictably high in overmature stands but unpredictable in young, immature, and mature stands. Forest fuel succession is discussed in relation to tree mortality, fuel buildup, and depletion.

  11. Application of Buckmaster Electrolyte Ion Leakage Test to Woody Biofuel Feedstocks

    SciTech Connect

    Broderick, Thomas F; Dooley, James H

    2014-08-28

    In an earlier ASABE paper, Buckmaster reported that ion conductivity of biomass leachate in aqueous solution was directly correlated with activity access to plant nutrients within the biomass materials for subsequent biological or chemical processing. The Buckmaster test involves placing a sample of the particles in a beaker of constant-temperature deionized water and monitoring the change in electrical conductivity over time. We adapted the Buckmaster method to a range of woody biomass and other cellulosic bioenergy feedstocks. Our experimental results suggest differences of electrolyte leakage between differently processed woody biomass particles may be an indicator of their utility for conversion in bioenergy processes. This simple assay appears to be particularly useful to compare different biomass comminution techniques and particle sizes for biochemical preprocessing.

  12. Demonstration of the BioBaler harvesting system for collection of small-diameter woody biomass

    SciTech Connect

    Langholtz, Matthew H; Caffrey, Kevin R; Barnett, Elliott J; Webb, Erin; Brummette, Mark W; Downing, Mark

    2011-12-01

    As part of a project to investigate sustainable forest management practices for producing wood chips on the Oak Ridge Reservation (ORR) for the ORNL steam plant, the BioBaler was tested in various Oak Ridge locations in August of 2011. The purpose of these tests and the subsequent economic analysis was to determine the potential of this novel woody biomass harvesting method for collection of small-diameter, low value woody biomass. Results suggest that opportunities may exist for economical harvest of low-value and liability or negative-cost biomass. (e.g., invasives). This could provide the ORR and area land managers with a tool to produce feedstock while improving forest health, controlling problem vegetation, and generating local employment.

  13. Do Wildfires Promote Woody Species Invasion in a Fire-Adapted Ecosystem? Post-fire Resprouting of Native and Non-native Woody Plants in Central Argentina.

    PubMed

    Herrero, M Lucrecia; Torres, Romina C; Renison, Daniel

    2016-02-01

    We asked whether prescribed fire could be a useful management tool to reduce invasion by non-native plants in an ecosystem where native plants are supposed to be adapted to fires. Specifically, we compare the post-fire resprouting response of native and non-native woody species in Chaco Serrano forest of central Argentina. The measurements were carried out in five burnt areas where we selected ten native and seven non-native species. Our response variables were (1) post-fire survival, (2) types of resprouts, and (3) the growth of the resprouts. Our main results show that one year after the fire, survivals of native and non-native species were 0.84 and 0.89, respectively, with variances in survival seven times smaller in the native species group. Type of resprout was also less variable in native species, while growth of the resprouts was similar in native and non-native groups. We interpret that in most cases, the burning a forest with mixed native and non-native plants through prescribed fires will not differentially stop the invasion by non-native woody species even in ecosystems which are presumed to be relatively resistant to fires such as our study area.

  14. Do Wildfires Promote Woody Species Invasion in a Fire-Adapted Ecosystem? Post-fire Resprouting of Native and Non-native Woody Plants in Central Argentina

    NASA Astrophysics Data System (ADS)

    Herrero, M. Lucrecia; Torres, Romina C.; Renison, Daniel

    2016-02-01

    We asked whether prescribed fire could be a useful management tool to reduce invasion by non-native plants in an ecosystem where native plants are supposed to be adapted to fires. Specifically, we compare the post-fire resprouting response of native and non-native woody species in Chaco Serrano forest of central Argentina. The measurements were carried out in five burnt areas where we selected ten native and seven non-native species. Our response variables were (1) post-fire survival, (2) types of resprouts, and (3) the growth of the resprouts. Our main results show that one year after the fire, survivals of native and non-native species were 0.84 and 0.89, respectively, with variances in survival seven times smaller in the native species group. Type of resprout was also less variable in native species, while growth of the resprouts was similar in native and non-native groups. We interpret that in most cases, the burning a forest with mixed native and non-native plants through prescribed fires will not differentially stop the invasion by non-native woody species even in ecosystems which are presumed to be relatively resistant to fires such as our study area.

  15. On the relative importance of pool morphology and woody debris to distributions of shrimp in a Puerto Rican headwater stream

    USGS Publications Warehouse

    Pyron, M.; Covich, A.P.; Black, R.W.

    1999-01-01

    In this paper, we report the sizes and distributional orientation of woody debris in a headwater rainforest stream in the Luquillo Experimental Forest (LEF), Puerto Rico. We also provide results of a 4-month study of a wood addition experiment designed to increase cover for benthic macroinvertebrates (freshwater shrimp). We added branch-sized woody debris to 20 pools in three streams. We trapped four species of freshwater shrimp (two species of benthic detritivores and two predatory shrimp species) during each of the 4 months following wood additions. An analysis of pool morphology (maximum depth, surface area and volume) provided a useful predictor of shrimp abundances. In general, numbers of shrimps increased with sizes of stream pools. A repeated measures ANOVA demonstrated no effect of woody debris additions on total numbers of shrimp per pool area. Two detritivore species (Atya lanipes, a filter feeder and Xiphocaris elongata, a shredder) decreased in abundance with increased woody debris and there was no statistical relationship between woody debris additions and predators (Macrobrachium carcinus and M. crenulatum). Small woody debris additions may have altered flow velocities that were important to filter-feeding Atya at the microhabitat scale, although the overall velocities within pools were not altered by wood additions. Lower numbers of Atya and Xiphocaris in two of the three streams may result from the occurrence of two predaceous fishes (American eel and mountain mullet) and more predatory Macrobrachium in these streams. One likely interpretation of the results of this study is that the stream pools in these study reaches had sufficient habitat structure provided by numerous rock crevices (among large rocks and boulders) to provide refuge from predators. Addition of woody debris did not add significantly to the existing structure. These results may not apply to stream channels with sand and gravel substrata where crevices and undercut banks are lacking

  16. Soil and water quality implications of production of herbaceous and woody energy crops

    SciTech Connect

    Tolbert, V.R.; Lindberg, J.E.; Green, T.H.

    1997-10-01

    Field-scale studies in three physiographic regions of the Tennessee Valley in the Southeastern US are being used to address the environmental effects of producing biomass energy crops on former agricultural lands. Comparison of erosion, surface water quality and quantity, and subsurface movement of water and nutrients from woody crops, switchgrass and agricultural crops began with crop establishment in 1994. Nutrient cycling, soil physical changes, and productivity of the different crops are also being monitored at the three sites.

  17. Spatial partitioning of water use by herbaceous and woody lifeforms in semiarid woodlands

    SciTech Connect

    Breshears, D.D.

    1993-12-31

    Ecological studies of soil moisture, plant water uptake, and community composition in semiarid regions have focused on differences with depth in the soil profile, yet there are many reasons to expect that moisture also varies with the presence or absence of woody vegetation. Plant and soil moisture relationships for three dominant species in a semiarid woodland, Bouteloua gracilis, Juniperus monosperma, and Pinus edulis, were studied for 1.5 years. Soil moisture varied by type of plant cover as well as by depth. Plant water potential and conductance differed among species and was related to spatial variability in soil moisture. Water potential for blue grama was most correlated with soil moisture in the 0-15 cm layer of intercanopies; juniper water potential was highly correlated with soil moisture in the 0-15 cm layer beneath tree canopies of either species, and pinyon water potential was only weakly correlated with soil moisture in the 15-30 cm depth interval beneath pinyons. Pinyons had consistently greater maximum conductance rates than junipers, even though pinyon conductance was more sensitive to reductions in soil moisture. The results from this study indicate that horizontal differences in the soil moisture profile associated with type of plant cover may be as important as differences in depth for predicting plant-water relationships. A simple model was hypothesized for predicting community composition of three lifeforms: Herbaceous plants, shallow-rooted woody plants, and deeper-rooted woody plants. Distributions of roots of each lifeform and plant-available water were defined with respect to four soil compartments that distinguish upper vs. lower and canopy vs. intercanopy soil regions. The model predicts that multiple combinations of herbaceous and woody biomass can exist at a site and was qualitatively consistent with field data from a climatic gradient.

  18. Energy Product Options for Eucalyptus Species Grown as Short Rotation Woody Crops

    PubMed Central

    Rockwood, Donald L.; Rudie, Alan W.; Ralph, Sally A.; Zhu, J.Y.; Winandy, Jerrold E.

    2008-01-01

    Eucalyptus species are native to Australia but grown extensively worldwide as short rotation hardwoods for a variety of products and as ornamentals. We describe their general importance with specific emphasis on existing and emerging markets as energy products and the potential to maximize their productivity as short rotation woody crops. Using experience in Florida USA and similar locations, we document their current energy applications and assess their productivity as short-term and likely long-term energy and related products. PMID:19325808

  19. Assessment of carbon in woody plants and soil across a vineyard-woodland landscape

    PubMed Central

    2011-01-01

    Background Quantification of ecosystem services, such as carbon (C) storage, can demonstrate the benefits of managing for both production and habitat conservation in agricultural landscapes. In this study, we evaluated C stocks and woody plant diversity across vineyard blocks and adjoining woodland ecosystems (wildlands) for an organic vineyard in northern California. Carbon was measured in soil from 44 one m deep pits, and in aboveground woody biomass from 93 vegetation plots. These data were combined with physical landscape variables to model C stocks using a geographic information system and multivariate linear regression. Results Field data showed wildlands to be heterogeneous in both C stocks and woody tree diversity, reflecting the mosaic of several different vegetation types, and storing on average 36.8 Mg C/ha in aboveground woody biomass and 89.3 Mg C/ha in soil. Not surprisingly, vineyard blocks showed less variation in above- and belowground C, with an average of 3.0 and 84.1 Mg C/ha, respectively. Conclusions This research demonstrates that vineyards managed with practices that conserve some fraction of adjoining wildlands yield benefits for increasing overall C stocks and species and habitat diversity in integrated agricultural landscapes. For such complex landscapes, high resolution spatial modeling is challenging and requires accurate characterization of the landscape by vegetation type, physical structure, sufficient sampling, and allometric equations that relate tree species to each landscape. Geographic information systems and remote sensing techniques are useful for integrating the above variables into an analysis platform to estimate C stocks in these working landscapes, thereby helping land managers qualify for greenhouse gas mitigation credits. Carbon policy in California, however, shows a lack of focus on C stocks compared to emissions, and on agriculture compared to other sectors. Correcting these policy shortcomings could create

  20. Biological and Physical Drivers of Coarse Woody Debris Respiration Following Moderate Forest Disturbance

    NASA Astrophysics Data System (ADS)

    Schmid, A. V.; Franklin, R. B.; Vogel, C. S.; Liebman, E.; Curtis, P.; Gough, C. M.

    2014-12-01

    Forest disturbances that cause plant mortality alter the net carbon (C) balance by increasing heterotrophic respiration associated with coarse woody debris (CWD) decomposition. Whether a forest transitions from a C sink to source following disturbance is largely a function of the quantity of additional CWD produced and the rate of woody debris decomposition. Coarse woody debris temperature, moisture, and microbial community composition are known to drive rates of heterotrophic respiration, but rarely have these factors been studied together across a gradient of wood decay and over time following disturbance. We used a large-scale experimental disturbance, in which early successional aspen (Populus spp.) and birch (Betula papyrifera) were killed via stem girdling within a 39 ha area, to study the effects of moderate disturbance on the forest C cycle. We quantified changes over time in CWD mass for a decade, before and after disturbance. We then conducted point measurements of CWD respiration, temperature and moisture, and quantified extracellular enzyme activity of enzymes associated with wood decomposition for five classes varying in extent of decay and standing woody debris. Process and inventory data are being used to estimate ecosystem CO2 efflux from CWD, which we will contrast with net ecosystem production (NEP) determined from long-term eddy covariance measurements of net CO2 exchange between the forest and atmosphere at the University of Michigan Biological Station (US-UMd) Ameriflux site. Our results will improve ecosystem model predictions of CWD respiration by incorporating both physical factors, such as temperature and wood moisture content, and biological factors, such as extracellular enzymatic activity of different functional types of decomposers.

  1. Short-rotation woody-crops program. Quarterly progress report for period ending May 31, 1981

    SciTech Connect

    Cushman, J.H.; Ranney, J.W.

    1982-04-01

    Progress of twenty projects in the Short Rotation Woody Crops Program is summarized for the period March 1 through May 31, 1981. Individual quarterly reports included from each of the projects discuss accomplishments within specific project objectives and identify recent papers and publications resulting from the research. The major project activities are species screening and genetic selection, stand establishment and cultural treatment, and harvest, collection, transportation, and storage.

  2. Short-rotation woody-crops program. Quarterly progress report for period ending August 31, 1981

    SciTech Connect

    Cushman, J.H.; Ranney, J.W.

    1982-04-01

    Progress of twenty-one projects in the Short Rotation Woody Crops Program is summarized for the period June 1 through August 31, 1981. Individual quarterly reports included from each of the projects discuss accomplishments within specific project objectives and identify recent papers and publications resulting from the research. The major program activities are species screening and genetic selection, stand establishment and cultural treatment, and harvest, collection, transportation, and storage.

  3. Technoeconomic Comparison of Biofuels: Ethanol, Methanol, and Gasoline from Gasification of Woody Residues (Presentation)

    SciTech Connect

    Tarud, J.; Phillips, S.

    2011-08-01

    This presentation provides a technoeconomic comparison of three biofuels - ethanol, methanol, and gasoline - produced by gasification of woody biomass residues. The presentation includes a brief discussion of the three fuels evaluated; discussion of equivalent feedstock and front end processes; discussion of back end processes for each fuel; process comparisons of efficiencies, yields, and water usage; and economic assumptions and results, including a plant gate price (PGP) for each fuel.

  4. Woody Vegetation Composition and Structure in Peri-urban Chongming Island, China

    NASA Astrophysics Data System (ADS)

    Zhao, Min; Escobedo, Francisco J.; Wang, Ruijing; Zhou, Qiaolan; Lin, Wenpeng; Gao, Jun

    2013-05-01

    Chongming, the world's largest alluvial island, is located within the municipality of Shanghai, China. Recent projects have now linked peri-urban Chongming to Shanghai's urban core and as a result will soon undergo substantial changes from urbanization. We quantitatively analyzed the structure and composition of woody vegetation across subtropical, peri-urban Chongming as a basis for sustainable management of these rapidly urbanizing subtropical ecosystems elsewhere. We used 178 permanent, random plots to statistically and spatially analyze woody plant composition and tree structure across the 1,041 km2 of Chongming. A total of 2,251 woody plants were measured comprising 42 species in 37 genera. We statistically and geospatially analyzed field data according to land uses and modeled air pollution removal by trees. Average tree diameter at breast height, total height, and crown widths on transportation land uses were greater than other land uses. These same values were lowest on forest land use and greater tree cover was associated with areas of increased anthropogenic activity. Less than 20 % of the woody vegetation was exotic and a species richness index was significantly different between land uses due to legacy effects. Composition of agriculture and forest land uses were similar to residential and transportation. Tree cover across Chongming was also estimated to annually remove 1,400 tons of air pollutants. We propose that this integrated and quantitative method can be used in other subtropical, peri-urban areas in developing countries to establish baseline trends for future sustainability objectives and to monitor the effects of urbanization and climate change.

  5. Woody riparian vegetation near selected streamgages in the western United States

    USGS Publications Warehouse

    Auble, Gregor T.; Friedman, Jonathan M.; Shafroth, Patrick B.; Merigliano, Michael F.; Scott, Michael L.

    2012-01-01

    Areal cover and occupancy of woody riparian species near 456 streamgages in the western United States were obtained from site visits during the growing seasons of 1996-2002. We made concomitant estimates of grazing intensity, channel stabilization and incision, gradient, sediment particle size, and nearby planting of Russian olive. The purpose of this publication is to describe the data set and make it available to other investigators in an electronic format.

  6. Woody vegetation composition and structure in peri-urban Chongming Island, China.

    PubMed

    Zhao, Min; Escobedo, Francisco J; Wang, Ruijing; Zhou, Qiaolan; Lin, Wenpeng; Gao, Jun

    2013-05-01

    Chongming, the world's largest alluvial island, is located within the municipality of Shanghai, China. Recent projects have now linked peri-urban Chongming to Shanghai's urban core and as a result will soon undergo substantial changes from urbanization. We quantitatively analyzed the structure and composition of woody vegetation across subtropical, peri-urban Chongming as a basis for sustainable management of these rapidly urbanizing subtropical ecosystems elsewhere. We used 178 permanent, random plots to statistically and spatially analyze woody plant composition and tree structure across the 1,041 km(2) of Chongming. A total of 2,251 woody plants were measured comprising 42 species in 37 genera. We statistically and geospatially analyzed field data according to land uses and modeled air pollution removal by trees. Average tree diameter at breast height, total height, and crown widths on transportation land uses were greater than other land uses. These same values were lowest on forest land use and greater tree cover was associated with areas of increased anthropogenic activity. Less than 20 % of the woody vegetation was exotic and a species richness index was significantly different between land uses due to legacy effects. Composition of agriculture and forest land uses were similar to residential and transportation. Tree cover across Chongming was also estimated to annually remove 1,400 tons of air pollutants. We propose that this integrated and quantitative method can be used in other subtropical, peri-urban areas in developing countries to establish baseline trends for future sustainability objectives and to monitor the effects of urbanization and climate change.

  7. Modeling respiration from snags and coarse woody debris before and after an invasive gypsy moth disturbance

    NASA Astrophysics Data System (ADS)

    Renninger, Heidi J.; Carlo, Nicholas; Clark, Kenneth L.; Schäfer, Karina V. R.

    2014-04-01

    Although snags and coarse woody debris are a small component of ecosystem respiration, disturbances can significantly increase the mass and respiration from these carbon (C) pools. The objectives of this study were to (1) measure respiration rates of snags and coarse woody debris throughout the year in a forest previously defoliated by gypsy moths, (2) develop models for dead stem respiration rates, (3) model stand-level respiration rates of dead stems using forest inventory and analysis data sets and environmental variables predisturbance and postdisturbance, and (4) compare total dead stem respiration rates with total ecosystem respiration and net ecosystem exchange. Respiration rates were measured on selected Pinus and Quercus snags and coarse woody debris each month for 1 year in a northeastern U.S. temperate forest. Multiple linear regression using environmental and biometric variables including wood temperature, diameter, density, species, and decay class was used to model respiration rates of dead stems. The mass of snags and coarse woody debris increased more than fivefold after disturbance and respiration rates increased more than threefold. The contribution of dead stems to total ecosystem respiration more than tripled from 0.85% to almost 3% and respiration from dead stems alone was approximately equal to the net ecosystem exchange of the forest in 2011 (fourth year postdisturbance). This study highlights the importance of dead stem C pools and fluxes particularly during disturbance and recovery cycles. With climate change increasing the ranges of many forest pests and pathogens, these data become particularly important for accurately modeling future C cycling.

  8. Survival, reproduction, and recruitment of woody plants after 14 years on a reforested landfill

    NASA Astrophysics Data System (ADS)

    Robinson, George R.; Handel, Steven N.; Schmalhofer, Victoria R.

    1992-03-01

    With the advent of modern sanitary landfill closure techniques, the opportunity exists for transforming municipal landfills into urban woodlands. While costs of fullscale reforestation are generally prohibitive, a modest planting of clusters of trees and shrubs could initiate or accelerate population expansions and natural plant succession from open field to diverse forest. However, among woody species that have been screened for use on landfills, these ecological potentials have not yet been investigated. We examined a 14-yr-old landfill plantation in New Jersey, USA, established to test tolerance of 19 species of trees and shrubs to landfill environments. We measured survivorship, reproduction, and recruitment within and around the experimental installation. Half of the original 190 plants were present, although survival and growth rates varied widely among species. An additional 752 trees and shrubs had colonized the plantation and its perimeter, as well as 2955 stems of vines. However, the great majority (>95%) of woody plants that had colonized were not progeny of the planted cohort, but instead belonged to 18 invading species, mostly native, bird-dispersed, and associated with intermediate stages of secondary plant succession. Based on this evidence, we recommend that several ecological criteria be applied to choices of woody species for the restoration of municipal landfills and similar degraded sites, in order to maximize rapid and economical establishment of diverse, productive woodlands.

  9. Field note: comparative efficacy of a woody evapotranspiration landfill cover following the removal of aboveground biomass.

    PubMed

    Schnabel, William; Munk, Jens; Byrd, Amanda

    2015-01-01

    Woody vegetation cultivated for moisture management on evapotranspiration (ET) landfill covers could potentially serve a secondary function as a biomass crop. However, research is required to evaluate the extent to which trees could be harvested from ET covers without significantly impacting their moisture management function. This study investigated the drainage through a six-year-old, primarily poplar/cottonwood ET test cover for a period of one year following the harvest of all woody biomass exceeding a height of 30 cm above ground surface. Results were compared to previously reported drainage observed during the years leading up to the coppice event. In the first year following coppice, the ET cover was found to be 93% effective at redirecting moisture during the spring/summer season, and 95% effective during the subsequent fall/winter season. This was slightly lower than the 95% and 100% efficacy observed in the spring/summer and fall/winter seasons, respectively, during the final measured year prior to coppice. However, the post-coppice efficacy was higher than the efficacy observed during the first three years following establishment of the cover. While additional longer-term studies are recommended, this project demonstrated that woody ET covers could potentially produce harvestable biomass while still effectively managing aerial moisture.

  10. Quantitative resistance traits and suitability of woody plant species for a polyphagous scarab, Popillia japonica Newman.

    PubMed

    Keathley, Craig P; Potter, Daniel A

    2008-12-01

    The Japanese beetle, Popillia japonica Newman, has an unusually broad host range among deciduous woody plants, yet it feeds only sparingly, or not at all, on certain species in the field. We evaluated beetles' preference, survival over time and fecundity on eight woody plant species historically rated as susceptible or resistant and, after verifying those ratings, tested whether resistance is correlated with so-called quantitative defense traits including leaf toughness, low nutrient content (water, nitrogen, and sugars), and relatively high amounts of tannins or saponins, traditionally associated with such plants. We further tested whether species unsuitable for Japanese beetles are also rejected by fall webworms, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), the expected outcome if the aforementioned traits serve as broad-based defenses against generalists. Choice tests supported historical resistance ratings for the selected species: tuliptree, lilac, dogwood, and Bradford callery pear were rejected by Japanese beetles, whereas sassafras, cherry plum, Virginia creeper, and littleleaf linden were readily eaten. Rejected species also were unsuitable for survival over time, or egg-laying, indicating beetles' inability to overcome the resistance factors through habituation, compensatory feeding, or detoxification. None of the aforementioned leaf traits was consistently higher or lower in the resistant or susceptible plants, and plant species rejected by Japanese beetles often were not rejected by fall webworms. Specialized secondary chemistry, not quantitative defenses, likely determines the Japanese beetle's dietary range among deciduous woody plant species it may encounter.

  11. Scaling Chromosomes for an Evolutionary Karyotype: A Chromosomal Tradeoff between Size and Number across Woody Species

    PubMed Central

    Liang, Guolu; Chen, Hong

    2015-01-01

    This study aims to examine the expected scaling relationships between chromosome size and number across woody species and to clarify the importance of the scaling for the maintenance of chromosome diversity by analyzing the scaling at the inter- & intra-chromosomal level. To achieve for the goals, chromosome trait data were extracted for 191 woody species (including 56 evergreen species and 135 deciduous species) from the available literature. Cross-species analyses revealed a tradeoff among chromosomes between chromosome size and number, demonstrating there is selective mechanism crossing chromosomes among woody species. And the explanations for the result were presented from intra- to inter-chromosome contexts that the scaling may be compromises among scale symmetry, mechanical requirements, and resource allocation across chromosomes. Therein, a 3/4 scaling pattern was observed between total chromosomes and m-chromosomes within nucleus which may imply total chromosomes may evolve from more to less. In addition, the primary evolutionary trend of karyotype and the role of m-chromosomes in the process of karyotype evolution were also discussed. PMID:26657837

  12. Overstory and understory relationships in longleaf pine plantations 14 years after thinning and woody control.

    SciTech Connect

    Harrington, Timothy, B.

    2011-09-09

    To develop silvicultural strategies for restoring longleaf pine (Pinus palustris Mill.) savannas, mortality and growth of overstory pines and midstory hardwoods and abundance and species richness of herbs were studied for 14 years after pine thinning and nonpine woody control. Pine cover in thinned stands was about half of that in nonthinned stands through year 5, but it lagged by only 8% and 3% in years 9 and 14, respectively, because of vigorous crown responses. Despite a cumulative mortality of 64% of hardwood stems from prescribed fires in years 0, 4, and 9, hardwood basal area in thinned stands (2.1 m2/ha) was three times that in nonthinned stands (0.7 m2/ha) in year 14. Thinning was associated with 13%-22% more cover and six to eight more species of herbs in years 3-8 but only 6% more cover and two more species in year 14 because of accelerated growth of pine cover and hardwood basal area. However, similar increases in cover and richness of herb species in the woody control treatment were retained through year 14 because it had sustained reductions in hardwood and shrub abundance. Silvicultural strategies that substantially delay encroachment by pines, hardwoods, and shrubs will be those most effective at retaining herb species in longleaf pine savannas, including planting pines at wide spacing, periodic thinning and woody control, and frequent burning.

  13. Effect of Woody Debris abundance on daytime refuge use by cotton mice.

    SciTech Connect

    Hinkelman, Travis, M.; Loeb, Susan, C.

    2007-07-01

    Abstract - Daytime refuges are important to nocturnal rodents for protection from predators and environmental extremes. Because refuges of forest-dwelling rodents are often associated with woody debris, we examined refuge use by 37 radio-collared Peromyscus gossypinus (cotton mice) in experimental plots with different levels of woody debris. Treatment plots had six times (≈ 60 m3/ha) the volume of woody debris as control plots (≈ 10 m3/ha). Of 247 refuges, 159 were in rotting stumps (64%), 32 were in root boles (13%), 19 were in brush piles (8%), and 16 were in logs (6%); 10 refuges could not be identified. Stumps were the most common refuge type in both treatments, but the distribution of refuge types was significantly different between treatment and control plots. Root boles and brush piles were used more on treatment plots than on control plots, and logs were used more on control plots than on treatment plots. Refuge type and vegetation cover were the best predictors of refuge use by cotton mice; root bole refuges and refuges with less vegetation cover received greater-than-expected use by mice. Abundant refuges, particularly root boles, may improve habitat quality for cotton mice in southeastern pine forests.

  14. Characterisation of the heterogeneous alkaline pulping kinetics of hemp woody core.

    PubMed

    Dang, Vinh; Nguyen, Kien Loi

    2006-08-01

    A model was developed, based on the power law of growth and Avrami's concepts in nuclei growth to describe the heterogeneous nature of alkaline pulping kinetics, taking into account the effects of effective alkali concentration and temperature. It was then applied against published data to estimate model parameters. The final form of the model applied to alkaline pulping of thin hemp woody core in flow-through reactors could be represented by a first order rate equation with a time-dependent rate constant: [-dY/dt = A.[OH-]b.exp (-E/RT)n.Y.t(n-1). The rate equations applied for delignification, cellulose and xylan losses. It was found that the heterogeneous kinetic models predicted well the delignification and xylan loss of hemp woody core, with R2 values of 0.96 and 0.97, respectively. The model was, however, less accurate in predicting cellulose loss. The values n, which could represent the acceleration/deceleration extent of growth of reacting volumes, were found to be less than unity. This demonstrated the heterogeneous characteristics of alkaline pulping for hemp woody core.

  15. Hydraulic conductivity, photosynthesis and leaf water balance in six evergreen woody species from fall to winter.

    PubMed

    Taneda, Haruhiko; Tateno, Masaki

    2005-03-01

    To confirm that freeze-thaw embolism is a primary stress for evergreen woody species in winter, hydraulic conductivity, photosynthesis and leaf water potential were measured during fall and winter in trees growing in a cool temperate zone (Nikko) and in a warm temperate zone (Tokyo). We examined two evergreen conifers that naturally occur in the cool temperate zone (Abies firma Siebold & Zucc. and Abies homolepis Siebold & Zucc.), and four evergreen broad-leaved woody species that are restricted to the warm temperate zone (Camellia japonica L., Cinnamomum camphora (L.) J. Presl, Ilex crenata Thunb. and Quercus myrsinaefolia Blume). In Tokyo, where no freeze-thaw cycles of xylem sap occurred, hydraulic conductivity, photosynthesis and water balance remained constant during the experimental period. In Nikko, where there were 38 daily freeze-thaw cycles by February, neither of the tracheid-bearing evergreen conifers showed xylem embolism or leaf water deficits. Similarly, the broad-leaved evergreen trees with small-diameter vessels did not exhibit severe embolism or water deficits and maintained CO(2) assimilation even in January. In contrast, the two broad-leaved evergreen trees with large-diameter vessels showed significantly reduced hydraulic conductivity and shoot die-back in winter. We conclude that freeze-thaw embolism restricts evergreen woody species with large-diameter vessels to the warm temperate zone, whereas other stresses limit the distribution of broad-leaved trees, that have small-diameter vessels, but which are restricted to the warm temperate zone.

  16. Biofuel manufacturing from woody biomass: effects of sieve size used in biomass size reduction.

    PubMed

    Zhang, Meng; Song, Xiaoxu; Deines, T W; Pei, Z J; Wang, Donghai

    2012-01-01

    Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes.

  17. Biogenic volatile organic compounds (BVOC) emitted and accumulated by herbaceous and woody California crops

    NASA Astrophysics Data System (ADS)

    Ormeño, E.; Fares, S.; Park, J.; Gentner, D. R.; Karlik, J. F.; Goldstein, A. H.

    2009-12-01

    Emissions from vegetation may substantially influence regional air quality in California. However, the emission potentials of many important crop species have not been extensively studied, although they comprise extensive areas of landcover within this state. A better knowledge of the emission rate at the species-specific level is critical for reducing uncertainties in emission inventories and evaluating emission model performance. In the present study we identify and quantify BVOC produced (emitted and stored) by leaves of 22 dominant agricultural woody and herbaceous crops in California. Emissions were studied by means of a dynamic cuvette system where a whole plant (herbaceous species) or a branch (woody species) was enclosed. Emitted BVOC were collected by passing air from the cuvette enclosing the branch through a glass tube packed with carbon based adsorbents. The adsorbents were later liquid extracted and concentrated in the laboratory. BVOCs stored in the plant tissues were extracted with an organic solvent, after plant grinding. Both BVOC emitted and BVOC stored were identified and quantified using the same GC-MS equipment. Most identified leaf emissions and stored compounds were terpenoids, but BVOC from other biosynthetic classes (benzenoids and fatty acid derivates)were not negligible. The relationship between different BVOC classes and between emitted and stored terpenoids will be presented. Differences between herbaceous and woody crops, and a variety of foliar secretory structures (e.g. secretory cavities, secretory ducts, glandular trichomes, and glands), will be evaluated in terms of BVOC content and emissions to the atmosphere.

  18. Specific gravity of woody tissue from lowland Neotropical plants: differences among forest types.

    PubMed

    Casas, Luisa Fernanda; Aldana, Ana María; Henao-Diaz, Francisco; Villanueva, Boris; Stevenson, Pablo R

    2017-02-27

    Wood density, or more precisely, wood specific gravity, is an important parameter when estimating above ground biomass, which has become a central tool for the management and conservation of forests around the world. When using biomass allometric equations for tropical forests, researchers are often required to assume phylogenetic trait conservatism, which allows to assign genus and family level wood specific gravity mean values, to many woody species. The lack of information on this trait for many Neotropical plant species has led to an imprecise estimation of the biomass stored in Neotropical forests. The data presented here has information of woody tissue specific gravity from 2,602 individual stems for 386 species, including trees, lianas and hemi-epiphytes of lowland tropical forests in Colombia. This dataset was produced by us collecting wood cores from woody species in five localities in the Orinoco and Magdalena Basins in Colombia. We found lower mean specific gravity values in várzea than in terra firme and igapó. This article is protected by copyright. All rights reserved.

  19. Historical climates explain contrasting dormancy-breaking requirements in North American, Asian, and European woody species

    NASA Astrophysics Data System (ADS)

    Zohner, Constantin M.; Benito, Blas M.; Fridley, Jason D.; Svenning, Jens-Christian; Renner, Susanne S.

    2016-04-01

    Leaf-out times in temperate woody species are determined by winter chilling and spring warming, with day length playing a minor role. The species-specific relative importance of these phenological cues determines the sensitivity of leaf unfolding to climate warming in the globe's temperate forests. Using experimental and monitoring data on leaf-out cues in 495 woody species [about 1/3rd each from Asia, Europe, and North America (NA)], we show that NA species have higher winter chilling and spring warming requirements than do European and Asian species of similar genetic stock. The continent effect remained significant when controlling for the modern climates that species are adapted to, suggesting that contrasting historic climate conditions led to the differentiation of leaf-out strategies among NA, European, and Asian plants. The NA flora experienced more and longer periods of climatic instability and harshness (esp. since the Pliocene) than did southern Europe and East Asia, which may explain why NA species have higher dormancy requirements and leaf-out later than Asian species, which are characterized by a more shallow dormancy. That species from Asia require significantly less chilling than their NA relatives suggests contrasting responses of NA and Asian temperate forests to continued climate warming. Earlier leaf-out in NA trees and shrubs will be constrained by unmet chilling requirements as winters get warmer, whereas Asian woody species generally lack such temperature limitations.

  20. Scaling Chromosomes for an Evolutionary Karyotype: A Chromosomal Tradeoff between Size and Number across Woody Species.

    PubMed

    Liang, Guolu; Chen, Hong

    2015-01-01

    This study aims to examine the expected scaling relationships between chromosome size and number across woody species and to clarify the importance of the scaling for the maintenance of chromosome diversity by analyzing the scaling at the inter- & intra-chromosomal level. To achieve for the goals, chromosome trait data were extracted for 191 woody species (including 56 evergreen species and 135 deciduous species) from the available literature. Cross-species analyses revealed a tradeoff among chromosomes between chromosome size and number, demonstrating there is selective mechanism crossing chromosomes among woody species. And the explanations for the result were presented from intra- to inter-chromosome contexts that the scaling may be compromises among scale symmetry, mechanical requirements, and resource allocation across chromosomes. Therein, a 3/4 scaling pattern was observed between total chromosomes and m-chromosomes within nucleus which may imply total chromosomes may evolve from more to less. In addition, the primary evolutionary trend of karyotype and the role of m-chromosomes in the process of karyotype evolution were also discussed.

  1. Woody encroachment and its consequences on hydrological processes in the savannah.

    PubMed

    Honda, Eliane A; Durigan, Giselda

    2016-09-19

    Woody encroachment due to changes in climate or in the disturbance regimes (fire and herbivory) has been observed throughout the savannah biome over the last century with ecological, hydrological and socioeconomic consequences. We assessed changes in tree density and basal area and estimated changes in rain interception by the canopies across a 5-year period over a biomass gradient in Cerrado vegetation protected from fire. We modelled throughfall, stemflow and net rainfall on the basis of tree basal area (TBA). Tree density increased by an average annual rate of 6.7%, basal area at 5.7% and rain interception by the canopies at 0.6% of the gross rainfall. Independent of the vegetation structure, we found a robust relationship of 0.9% less rainfall reaching the ground as TBA increases by 1 m(2) ha(-1) Increases in tree biomass with woody encroachment may potentially result in less water available for uptake by plants and to recharge rivers and groundwater reserves. Given that water is a seasonally scarce resource in all savannahs, woody encroachment may threaten the ecosystem services related to water resources.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.

  2. A dynamic leaf gas-exchange strategy is conserved in woody ...

    EPA Pesticide Factsheets

    Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water and nutrient cycling of forests. Researchers have reported that stomata regulate leaf gas-exchange around “set points” that include a constant leaf internal [CO2], ci, a constant drawdown in CO2 (ca - ci), and a constant ci/ca. Because these set points can result in drastically different consequences for leaf gas-exchange, it will be essential for the accuracy of Earth systems models that generalizable patterns in leaf gas-exchange responses to ca be identified if any do exist. We hypothesized that the concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these set point strategies, would provide a unifying framework for understanding leaf gas-exchange responses to ca. We analyzed studies reporting C stable isotope ratio (δ13C) or photosynthetic discrimination (∆13C) from woody plant taxa that grew across ca spanning at least 100 ppm for each species investigated. From these data we calculated ci, and in combination with known or estimated ca, leaf gas-exchange regulation strategies were assessed. Overall, our analyses does not support the hypothesis that trees are canalized towards any of the proposed set points, particularly so for a constant ci. Rather, the results are consistent with the hypothesis that stomatal optimization regulates leaf gas

  3. Modeling aboveground tree woody biomass using national-scale allometric methods and airborne lidar

    NASA Astrophysics Data System (ADS)

    Chen, Qi

    2015-08-01

    Estimating tree aboveground biomass (AGB) and carbon (C) stocks using remote sensing is a critical component for understanding the global C cycle and mitigating climate change. However, the importance of allometry for remote sensing of AGB has not been recognized until recently. The overarching goals of this study are to understand the differences and relationships among three national-scale allometric methods (CRM, Jenkins, and the regional models) of the Forest Inventory and Analysis (FIA) program in the U.S. and to examine the impacts of using alternative allometry on the fitting statistics of remote sensing-based woody AGB models. Airborne lidar data from three study sites in the Pacific Northwest, USA were used to predict woody AGB estimated from the different allometric methods. It was found that the CRM and Jenkins estimates of woody AGB are related via the CRM adjustment factor. In terms of lidar-biomass modeling, CRM had the smallest model errors, while the Jenkins method had the largest ones and the regional method was between. The best model fitting from CRM is attributed to its inclusion of tree height in calculating merchantable stem volume and the strong dependence of non-merchantable stem biomass on merchantable stem biomass. This study also argues that it is important to characterize the allometric model errors for gaining a complete understanding of the remotely-sensed AGB prediction errors.

  4. Determining effects of woody vegetation on flood flow and sediment transport

    NASA Astrophysics Data System (ADS)

    Griffin, E. R.; Smith, J. D.; Friedman, J. M.; Vincent, K. R.

    2008-12-01

    Predicting the outcome of flow and sediment transport events quantitatively has been difficult due to the complex nature of stream systems and the effects of woody vegetation on flow. Predictive, process-based models of flow and sediment transport developed by our group during the past decade compute flow from fluid mechanical theory without empirically adjusted coefficients. Our models generate local hydraulic roughness fields from known physical characteristics and distributions of woody vegetation and topography determined from field measurements. An opportunity has arisen to apply these models to reconstruct a recent flood that caused large-scale geomorphic change and to test model predictions using data from field observations and satellite imagery. In 2003 application of an herbicide by helicopter for control of saltcedar (Tamarix spp.) killed almost all woody riparian vegetation along a 12-km reach of the Rio Puerco in north-central New Mexico. Subsequently, a large flood in August 2006 caused widespread erosion of the channel banks in the sprayed reach, where the channel widened by 84 percent on average. About 680,000 m3 of sediment eroded from the banks was deposited within 5 to 10 km downstream. Channel and floodplain widths remained virtually the same as prior to the flood upstream and downstream from the sprayed reach. Because of our previous work in the area, we were fortunate to have a large dataset of channel and floodplain geometry prior to the flood, including long-term channel cross sections, a detailed longitudinal profile, high-resolution imagery, and LIDAR topography. After the flood we resurveyed cross sections and the longitudinal profile and acquired post-flood imagery. Flood water-surface elevations determined from surveyed high-water marks provide constraints on the flood- flow depth with distance downstream and provide water-surface slopes. Satellite imagery and GPS survey data acquired after the flood are used to test the coupled

  5. Tree mortality, canopy turnover, and woody detritus in old cove forests of the southern Appalachians

    USGS Publications Warehouse

    Busing, R.T.

    2005-01-01

    A long-term study of tree mortality, canopy turnover, and coarse woody detritus inputs was conducted in cove forests of the Great Smoky Mountains, Tennessee, USA. Seven old-growth stands were studied over a 10-yr period using 0.6-1.0 ha plots. Annual mortality of trees >10 cm dbh was 0.5-1.4% among stands (mean 0.7%), The highest mortality rate among canopy trees was exhibited by trees >80 cm dbh. An increase in mortality rate with canopy tree size was evident for two (Tsuga canadensis and Acer saccharum) of the three most abundant species in the forest. The increase in mortality with tree size had implications for canopy turnover and detritus input. Gap disturbance frequency was estimated at 0.008-0.019 forest area/yr, giving a return interval of ???130 yr or less. Standing death was the most common mode of mortality (59%). Annual rates of snag formation were 1.4 snags/ha for trees >10 cm dbh and 0.4 snags/ha for trees >50 cm dbh. The density of large snags (>50 cm dbh) was 5 snags/ha. Snags accounted for 8% of the total standing tree basal area and 23% of the coarse woody detritus mass (total of 48 Mg/ ha). The mean annual rate of coarse woody detritus input was 3.0 Mg/ha. A decay rate constant was estimated at 0.07, yielding a detritus half-life of 10 yr. Although mean mortality rates and canopy turnover in old cove forests were moderate in comparison with other old forests of eastern North America, input and accumulation of coarse woody detritus were high for the region. This resulted, in part, from the relatively large sizes attained by canopy trees and the fact that larger trees tended to suffer higher mortality. In comparison to forests worldwide, rates of mortality, canopy gap formation, and decay of coarse woody detritus were intermediate.

  6. Methane and Carbon Dioxide Fluxes from Stems, Soils, and Coarse Woody Debris in a Temperate Forest

    NASA Astrophysics Data System (ADS)

    Warner, D. L.; Villarreal, S.; McWilliams, K.; Inamdar, S. P.; Vargas, R.

    2015-12-01

    Quantifying the magnitude and variability of greenhouse gas fluxes from different terrestrial carbon pools is necessary for enhancing understanding of terrestrial carbon cycling. While much more is known about variability CO2 fluxes, we have little information on how CH4 fluxes vary across multiple carbon pools within terrestrial ecosystems. We measured fluxes of CH4 and CO2 from living tree stems, soils, and coarse woody debris within a temperate forested watershed during the growing season (May-November). Fluxes of both CH4 and CO2 were significantly different among carbon pools. Living tree stems were weak sources of both CH4 and CO2 with seasonal means (± 1 SD) of 0.08 ± 0.19 nmol CH4 m-2 s-1 and 1.16 ± 1.21 μmol CO2 m-2 s-1. Soils were sinks of CH4 and sources of CO2 with seasonal means (± 1 SD) of -2.00 ± 1.41 nmol CH4 m-2 s-1 and 3.07 ± 2.10 μmol CO2 m-2 s-1. Fluxes of CH4 and CO2 from coarse woody debris were largely variable relative to the other pools with seasonal means (± 1 SD) of -0.21 ± 0.76 nmol CH4 m-2 s-1 and 2.61 ± 2.50 μmol CO2m-2 s-1. Gas fluxes varied significantly (p < 0.05) between sampling sites for both living stems and coarse woody debris, but not for soils. For living stems, this variability was explained by differences in tree species, where N. sylvatica had largest seasonal mean flux of CH4 and L. tulipifera had the largest seasonal mean flux of CO2. For woody debris sites, the variability was explained wood density, with dense, fresh wood acting as CH4 sources, and less dense, decayed wood acting as CH4 sinks. Our results show homogeneity in soil CH4 and CO2 fluxes, but a large heterogeneity in fluxes from tree stems and coarse woody debris. These results provide insights on how forest management strategies could influence greenhouse gas emissions from forested watersheds.

  7. Behavioral responses of cotton mice (Peromyscus gossypinus) to large amounts of coarse woody debris.

    SciTech Connect

    Hinkleman, Travis M.

    2004-08-01

    Hinkleman, Travis M. 2004. MS Thesis. Clemson University, Clemson, South Carolina. 62 pp. Coarse woody debris (CWD) is any log, snag, or downed branch >10 cm in diameter. As a major structural feature of forest ecosystems, CWD serves as an important habitat component for a variety of organisms. Rodents frequently use CWD for travel routes and daytime refugia. Although rodents are known to use CWD extensively and selectively, the use and selection of CWD by rodents may vary according to the abundance of CWD. The purpose of this project was to determine the effect of CWD abundance on the habitat use patterns of a common terrestrial rodent, the cotton mouse (Peromyscus gossypinus). I tracked cotton mice with fluorescent pigments and radiotelemetry in 6 plots, situated in loblolly pine (Pinus taeda) stands, with manipulated levels of woody debris. Treatment plots had 6x the amount of woody debris as control plots. I determined log use and movement patterns from the paths produced by powder-tracking, and I identified daytime refugia by radio-tracking. Travel along logs was almost exclusively associated with the surface of logs (91%). The proportion of a movement path associated with logs was not the best predictor of path complexity; rather, the sex of the individual was the only significant indicator of relative displacement (i.e., males moved farther from the point of release than females) and vegetation cover was the only significant predictor of mean turning angle (i.e., increasing vegetation cover yielded more convoluted paths). Mice used logs to a greater extent on treatment plots (23.7%) than mice on control plots (4.8%). Mice on treatment plots used logs with less decay, less ground contact, and more bark than logs used by mice on control plots. Differences in log use patterns were largely a result of the attributes of available logs, but mice used logs selectively on treatment plots. Refuges were highly associated with woody debris, including refuges in rotting

  8. Woody debris along an upland chronosequence in boreal Manitoba and its impact on long-term carbon storage

    USGS Publications Warehouse

    Manies, K.L.; Harden, J.W.; Bond-Lamberty, B. P.; O'Neill, K. P.

    2005-01-01

    This study investigated the role of fire-killed woody debris as a source of soil carbon in black spruce (Picea mariana (Mill.) BSP) stands in Manitoba, Canada. We measured the amount of standing dead and downed woody debris along an upland chronosequence, including wood partially and completely covered by moss growth. Such woody debris is rarely included in measurement protocols and composed up to 26% of the total amount of woody debris in older stands, suggesting that it is important to measure all types of woody debris in ecosystems where burial by organic matter is possible. Based on these data and existing net primary production (NPP) values, we used a mass-balance model to assess the potential impact of fire-killed wood on long-term carbon storage at this site. The amount of carbon stored in deeper soil organic layers, which persists over millennia, was used to represent this long-term carbon. We estimate that between 10% and 60% of the deep-soil carbon is derived from wood biomass. Sensitivity analyses suggest that this estimate is most affected by the fire return interval, decay rate of wood, amount of NPP, and decay rate of the char (postfire) carbon pool. Landscape variations in these terms could account for large differences in deep-soil carbon. The model was less sensitive to fire consumption rates and to rates at which standing dead becomes woody debris. All model runs, however, suggest that woody debris plays an important role in long-term carbon storage for this area. ?? 2005 NRC Canada.

  9. Changes in soil nitrogen storage and δ15N with woody plant encroachment in a subtropical savanna parkland landscape

    NASA Astrophysics Data System (ADS)

    Boutton, T. W.; Liao, J. D.

    2010-09-01

    Subtropical woodlands dominated by N-fixing tree legumes have largely replaced grasslands in the Rio Grande Plains, southwestern United States, during the past century. To evaluate the impact of this vegetation change on the N cycle, we measured the mass and isotopic composition (δ15N) of N in the soil system of remnant grasslands and woody plant stands ranging in age from 10 to 130 years. Nitrogen accumulated at linear rates following woody encroachment in the litter (0.10-0.14 g N m-2 yr-1), roots (0.63-0.98 g N m-2 yr-1), and soils (0.75-3.50 g N m-2 yr-1), resulting in a 50%-150% increase in N storage in the soil system (0-30 cm) in woody stands older than 60 years. Simultaneous decreases in soil δ15N of up to 2‰ in the upper 30 cm of the profile are consistent with a scenario in which N inputs have exceeded losses following woody encroachment and suggest N accrual was derived from symbiotic N fixation by tree legumes and/or differential atmospheric N deposition to wooded areas. Vertical uplift and lateral transfer of N by the more deeply and intensively rooted woody plants may have contributed to N accumulation in wooded areas, but soil δ15N values are inconsistent with this explanation. N accumulation following woody encroachment may alter soil N availability, species interactions and successional dynamics, flux rates of key trace gases such as NOX and N2O and ecosystem C sequestration. Given the geographic dimensions of woody encroachment, these results may have implications for atmospheric composition and the climate system.

  10. Woody debris transport modelling by a coupled DE-SW approach

    NASA Astrophysics Data System (ADS)

    Persi, Elisabetta; Petaccia, Gabriella; Sibilla, Stefano

    2016-04-01

    The presence of wood in rivers is gaining more and more attention: on one side, the inclusion of woody debris in streams is emphasized for its ecological benefits; on the other hand, particular attention must be paid to its management, not to affect hydraulic safety. Recent events have shown that wood can be mobilized during floodings (Comiti et al. 2008, Lange and Bezzola 2006), aggravating inundations, in particular near urban areas. For this reason, the inclusion of woody debris influence on the prediction of flooded areas is an important step toward the reduction of hydraulic risk. Numerical modelling plays an important role to this purpose. Ruiz-Villanueva et al. (2014) use a two-dimensional numerical model to calculate the kinetics of cylindrical woody debris transport, taking into account also the hydrodynamic effects of wood. The model here presented couples a Discrete Element approach (DE) for the calculation of motion of a cylindrical log with the solution of the Shallow Water Equations (SW), in order to simulate woody debris transport in a two-dimensional stream. In a first step, drag force, added mass force and side force are calculated from flow and log velocities, assuming a reference area and hydrodynamic coefficients taken from literature. Then, the equations of dynamics are solved to model the planar roto-translation of the wooden cylinder. Model results and its physical reliability are clearly affected by the values of the drag and side coefficients, which in turn depend upon log submergence and angle towards the flow direction. Experimental studies to evaluate drag and side coefficients can be found for a submerged cylinder, with various orientations (Gippel et al. 1996; Hoang et al. 2015). To extend such results to the case of a floating (non-totally submerged) cylinder, the authors performed a series of laboratory tests whose outcomes are implemented in the proposed DE-SW model, to assess the effects of these values on the dynamic of woody

  11. Ecosystem Impacts of Woody Encroachment In Texas: A Spatial Analysis Using AVIRIS

    NASA Technical Reports Server (NTRS)

    Martin, Roberta E.; Asner, Gregory P.

    2004-01-01

    Woody encroachment, the increase of woody plant density relative to herbaceous vegetation, has been documented in drylands of Texas as well as worldwide (Archer 1994, Harrington and Harman 1995, Moleele et al. 2002). Over-grazing, fire suppression and climate change are implicated in the shift from open grasslands to ecosystems now populated by trees and shrubs (Scholes and Archer 1997, Archer et al. 2001), such as Prosopis glandulosa var. glandulosa (honey mesquite) in north Texas (Teague et al. 1997, Ansley et al. 2001, Asner et al. 2003a). Several studies have examined changes in ecosystem properties accompanying woody vegetation encroachment in the Southwest U.S., with research focused on increases in plant and soil carbon (C) and nitrogen (N) stores (Hoffman and Jackson 2000, Asner et al. 2003a), isotopic shifts in these pools (Boutton 1999, Archer et al. 2001), and increases in N cycling rates (Rundel et al. 1982, Hibbard et al. 2001). However, little is known regarding the impact of woody encroachment on N trace gas emissions from dryland regions such as Texas. NOx is produced in the soil during the processes of nitrification and denitrification (Firestone and Davidson 1989). The total N efflux from soils is most directly influenced by the internal cycling of N, which at a regionalscale, is controlled by the inputs and availability of N from vegetation via litterfall and subsequent decomposition (Robertson et al. 1989). Although plot-scale studies are critical to understanding controls over N oxide emissions, regionalization of the measurements is impeded by spatial variation in the factors contributing most to N cycling processes: soil properties (affecting soil moisture regimes and N stocks) and vegetation cover (affecting litter inputs and N uptake). While broad patterns in ecosystem structure and vegetation composition co-vary with general patterns of trace gas emissions (Matson 1997), there is no easily measured index of N availability that can be

  12. Biodiversity of Soil Microbial Communities Following Woody Plant Invasion of Grassland: An Assessment Using Molecular Methods

    NASA Astrophysics Data System (ADS)

    Kantola, I. B.; Gentry, T. J.; Filley, T. R.; Boutton, T. W.

    2012-12-01

    Woody plants have encroached into grasslands, savannas, and other grass-dominated ecosystems throughout the world during the last century. This dramatic vegetation change is likely driven by livestock grazing, altered fire frequencies, elevated atmospheric CO2 concentrations, and/or changes in atmospheric deposition patterns. Woody invasion often results in significant changes in ecosystem function, including alterations in above- and belowground primary productivity, soil C, N, and P storage and turnover, and the size and activity of the soil microbial biomass pool. The purpose of this study was to examine the relationships and interactions between plant communities and soil microbial communities in the Rio Grande Plains region of southern Texas where grasslands have been largely replaced by woodlands. Research was conducted along a successional chronosequence representing the stages of woody plant encroachment from open grassland to closed-canopy woodland. To characterize soil microbial community composition, soil samples (0-7.5 cm) were collected in remnant grasslands (representing time 0) and near the centers of woody plant clusters, groves, and drainage woodlands ranging in age from 10 to 130 yrs. Ages of woody plant stands were determined by dendrochronology. Community DNA was extracted from each soil sample with a MoBio PowerMax Soil DNA isolation kit. The DNA concentrations were quantified on a NanoDrop ND-1000 spectrophotometer and diluted to a standard concentration. Pyrosequencing was performed by the Research and Testing Laboratory (Lubbock, TX) according to Roche 454 Titanium chemistry protocols. Samples were amplified with primers 27F and 519R for bacteria, and primers ITS1F and ITS4 for fungi. Sequences were aligned using BioEdit and the RDP Pipeline and analyzed in MOTHUR. Non-metric multidimensional scaling of the operational taxonomic units identified by pyrosequencing revealed that both bacterial and fungal community composition were

  13. The spatial pattern and dominant drivers of woody cover change in Latin America and Caribbean from 2001 to 2010

    NASA Astrophysics Data System (ADS)

    Clark, M.; Aide, T.; Riner, G.; Redo, D.; Grau, H.; Bonilla-Moheno, M.; Lopez-Carr, D.; Levy, M.

    2011-12-01

    Change in woody vegetation (i.e., forests, shrublands) is a major component of global environmental change: it directly affects biodiversity, the global carbon budget, and ecosystem function. For several decades, remote sensing technology has been used to document deforestation in Latin America and the Caribbean (LAC), although mostly at local to regional scales (e.g., moist forests of the Amazon basin). Most studies have focused on forest loss, some local-scale studies have mapped forest recovery, with contrasting forest dynamics attributed to shifting demographic and socio-economic factors. For example, local population change (rural-urban migration) can stimulate forest recovery on abandoned land, while increasing global food demand may drive regional expansion of mechanized agriculture. However, there are no studies in LAC that simultaneously map both loss and gain in woody vegetation at continental, national, and municipality scales with consistent data sources, methods and accuracy; and thus, we lack a comprehensive assessment of the spatial distribution of woody vegetation change and the relative importance of the multi-scale drivers of this change. We overcame this limitation by producing annual land-cover maps between 2001 and 2010 for each of the >16,000 municipalities in LAC. We focused on mapping municipality-scale trends in three broad classes: woody vegetation, mixed woody/plantations, and agriculture/herbaceous vegetation. Our area estimates show that woody vegetation change during the past decade was dominated by deforestation, or loss (-541,830 km2), particularly in the Amazon basin moist forest and the tropical-subtropical Cerrado and Chaco ecoregions, where large swaths of forest have been transformed to pastures and agricultural lands. Extensive areas (362,431 km2) in LAC also gained woody vegetation, particularly in regions too dry or too steep for modern agriculture, including the desert/xeric shrub biome in NE Brazil and northern Mexico, the

  14. Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation

    PubMed Central

    Bakker, Elisabeth S.; Gill, Jacquelyn L.; Johnson, Christopher N.; Vera, Frans W. M.; Sandom, Christopher J.; Asner, Gregory P.; Svenning, Jens-Christian

    2016-01-01

    Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World’s terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions. PMID:26504223

  15. Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation.

    PubMed

    Bakker, Elisabeth S; Gill, Jacquelyn L; Johnson, Christopher N; Vera, Frans W M; Sandom, Christopher J; Asner, Gregory P; Svenning, Jens-Christian

    2016-01-26

    Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World's terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions.

  16. Vegetation types, dominant compositions, woody plant diversity and stand structure in Trishna Wildlife Sanctuary of Northeast India.

    PubMed

    Majumdar, Koushik; Datta, B K

    2015-03-01

    Present study was carried out to assess the vegetation types, diversity and phytosociological status of woody plants in Trishna Wildlife Sanctuary of Tripura, Northeast India. Vegetation data was derived by 25 line transects (10 m wide and 500 m length, each 0.5 ha size). All woody species at >10 cm gbh (Girth at Breast Height) within each plots were measured and counted. A total of six forest types were classified by cluster analysis using Importance Value Index (IVI) of 289 woody species. Species diversity, forest structure and woody community associations were evaluated and discussed. One way ANOVA revealed significant differences in all species diversity measures and stand structure along the forest types. Distribution of stem density at ten different gbh classes showed reverse J-shaped curves. Population status of woody plants was also examined through grouping of all individuals into four population age stages viz. sapling (<30 cm gbh), adult (> or = 30 - <120 cm gbh), mature (>120 - 210 cm gbh) and old (> or =210 cm). To observe dominant composition and species population trend, IVI of top ten dominant species from all forest types were tabulated. The present study suggested that Trishna Wildlife Sanctuary is an important habitat in Tripura from floristic point of view and it should be conserved on priority basis for remaining wildlife endurances and monitor for forest livelihoods products for sustainable biodiversity conservation in this region.

  17. The Eucalyptus grandis R2R3-MYB transcription factor family: evidence for woody growth-related evolution and function.

    PubMed

    Soler, Marçal; Camargo, Eduardo Leal Oliveira; Carocha, Victor; Cassan-Wang, Hua; San Clemente, Hélène; Savelli, Bruno; Hefer, Charles A; Paiva, Jorge A Pinto; Myburg, Alexander A; Grima-Pettenati, Jacqueline

    2015-06-01

    The R2R3-MYB family, one of the largest transcription factor families in higher plants, controls a wide variety of plant-specific processes including, notably, phenylpropanoid metabolism and secondary cell wall formation. We performed a genome-wide analysis of this superfamily in Eucalyptus, one of the most planted hardwood trees world-wide. A total of 141 predicted R2R3-MYB sequences identified in the Eucalyptus grandis genome sequence were subjected to comparative phylogenetic analyses with Arabidopsis thaliana, Oryza sativa, Populus trichocarpa and Vitis vinifera. We analysed features such as gene structure, conserved motifs and genome location. Transcript abundance patterns were assessed by RNAseq and validated by high-throughput quantitative PCR. We found some R2R3-MYB subgroups with expanded membership in E. grandis, V. vinifera and P. trichocarpa, and others preferentially found in woody species, suggesting diversification of specific functions in woody plants. By contrast, subgroups containing key genes regulating lignin biosynthesis and secondary cell wall formation are more conserved across all of the species analysed. In Eucalyptus, R2R3-MYB tandem gene duplications seem to disproportionately affect woody-preferential and woody-expanded subgroups. Interestingly, some of the genes belonging to woody-preferential subgroups show higher expression in the cambial region, suggesting a putative role in the regulation of secondary growth.

  18. Establishment of woody riparian vegetation in relation to annual patterns of streamflow, Bill Williams River, Arizona

    USGS Publications Warehouse

    Shafroth, P.B.; Auble, G.T.; Stromberg, J.C.; Patten, D.T.

    1998-01-01

    Previous studies have revealed the close coupling of components of annual streamflow hydrographs and the germination and establishment of Populus species. Key hydrograph components include the timing and magnitude of flood peaks, the rate of decline of the recession limb, and the magnitude of base flows. In this paper, we retrospectively examine establishment of four woody riparian species along the Bill Williams River, Arizona, USA, in the context of annual patterns of streamflow for the years 1993-1995. The four species examined were the native Populus fremontii, Salix gooddingii, and Baccharis salicifolia and the exotic Tamarix ramosissima. We modeled locations suitable for germination of each species along eight study transects by combining historic discharge data, calculated stage-discharge relationships, and seed-dispersal timing observations. This germination model was a highly significant predictor of seedling establishment. Where germination was predicted to occur, we compared values of several environmental variables in quadrats where we observed successful establishment with quadrats where establishment was unsuccessful. The basal area of mature woody vegetation, the maximum annual depth to ground water, and the maximum rate of water-table decline were the variables that best discriminated between quadrats with and without seedlings. The results of this study suggest that the basic components of models that relate establishment of Populus spp. to annual patterns of streamflow may also be applicable to other woody riparian species. Reach-to-reach variation in stage-discharge relationships can influence model parameters, however, and should be considered if results such as ours are to be used in efforts to prescribe reservoir releases to promote establishment of native riparian vegetation.

  19. Research to develop improved production methods for woody and herbaceous biomass crops

    SciTech Connect

    Ferrell, J.E.; Wright, L.L.; Tuskan, G.A.

    1995-09-01

    DOE`s Biofuels Feedstock Development Program (BFDP) has led the nation in developing short-rotation woody crops (SRWC) and herbaceous energy crops (HEC) as feedstocks for renewable energy. Over the past 15 years, the BFDP has examined the performance of 154 woody species and 35 herbaceous species in field trials across the US. One result of this effort to date has been the prescription of silvicultural systems for hybrid poplars and hybrid willows and agricultural systems for switchgrass. Selected clones of woody species are producing dry weight yields in research plots on agricultural land that are 3 to 7 times greater than those obtained from mixed species stands on forest land, and at least 2 times the yields of southern plantation pines. Selected switchgrass varieties are producing dry weight yields 2 to 7 times greater than average forage grass yields on similar sites. Crop development research is continuing efforts to translate this potential, in a sustainable manner, to larger, more geographically diverse acreage. Research on environmental aspects of biomass crop production are aimed at developing sustainable systems that will contribute to the biodiversity of agricultural landscapes. Systems integration aims to understand all factors affecting bringing the crop to market. Factors affecting price and potential supplies of biomass crops are being evaluated at regional and national scales. Scale-up studies, feasibility analysis and demonstrations are establishing actual costs and facilitating the commercialization of integrated biomass systems. Information management and dissemination activities are facilitating the communication of results among a community of researchers, policymakers, and potential users and producers of energy crops.

  20. Effects of woody vegetation on overbank sand transport during a large flood, Rio Puerco, New Mexico

    NASA Astrophysics Data System (ADS)

    Griffin, Eleanor R.; Perignon, Mariela C.; Friedman, Jonathan M.; Tucker, Gregory E.

    2014-02-01

    Distributions of woody vegetation on floodplain surfaces affect flood-flow erosion and deposition processes. A large flood along the lower Rio Puerco, New Mexico, in August 2006 caused extensive erosion in a reach that had been sprayed with herbicide in September 2003 for the purpose of saltcedar (Tamarix spp.) control. Large volumes of sediment, including a substantial fraction of sand, were delivered to the reach downstream, which had not been treated with herbicide. We applied physically based, one-dimensional models of flow and suspended-sediment transport to compute volume concentrations of sand in suspension in floodplain flow at a site within the sprayed reach and at a site downstream from the sprayed reach. We computed the effects of drag on woody stems in reducing the skin friction shear stress, velocity of flow, and suspended-sand transport from open paths into patches of dense stems. Total flow and suspended-sand fluxes were computed for each site using well-constrained flood-flow depths, water-surface slopes, and measured shrub characteristics. Results show that flow in open paths carried high concentrations of sand in suspension with nearly uniform vertical distributions. Drag on woody floodplain stems reduced skin friction shear stresses by two orders of magnitude, yet sufficient velocities were maintained to transport sand more than 50 m into fields of dense, free-surface-penetrating stems. An increase in shrub canopy extent from 31% in the sprayed reach site to 49% in the downstream site was found to account for 69% of the computed decrease in discharge between the two sites. The results demonstrate the need to compute the spatial distribution of skin friction shear stress in order to effectively compute suspended-sand transport and to predict the fate of sediment and contaminants carried in suspension during large floods.

  1. Modeling the flow resistance of woody vegetation using physically based properties of the foliage and stem

    NASA Astrophysics Data System (ADS)

    Västilä, Kaisa; Järvelä, Juha

    2014-01-01

    Both the foliage and stem essentially influence the flow resistance of woody plants, but their different biomechanical properties complicate the parameterization of foliated vegetation for modeling. This paper investigates whether modeling of flow resistance caused by natural woody vegetation can be improved using explicit description of both the foliage and stem. For this purpose, we directly measured the drag forces of Alnus glutinosa, Betula pendula, Salix viminalis, and Salix x rubens twigs in a laboratory flume at four foliation levels, parameterized with the leaf-area-to-stem-area ratio AL/AS. The species differed in the foliage drag but had approximately equal stem drag. For the foliated twigs, increasing AL/AS was found to increase the reconfiguration and the share of the foliage drag to the total drag. The experiments provided new insight into the factors governing the flow resistance of natural woody vegetation and allowed us to develop a model for estimating the vegetative friction factor using the linear superposition of the foliage and stem drag. The model is novel in that the foliage and stem are separately described with physically based parameters: drag coefficients, reconfiguration parameters, and leaf area and frontal-projected stem area per ground area. The model could satisfactorily predict the flow resistance of twig to sapling-sized specimens of the investigated species at velocities of 0.05-1 m/s. As a further benefit, the model allows exploring the variability in drag and reconfiguration associated with differing abundance of the foliage in relation to the stem.

  2. [Regeneration characteristics of woody plant seedlings in typical secondary forests in Qinling Mountains].

    PubMed

    Kang, Bing; Liu, Shi-Rong; Wang, De-Xiang; Zhang, Ying; Liu, Hong-Ru; Du, Yan-Ling

    2011-12-01

    By using sampling plot method, an investigation was conducted on the regeneration characteristics of woody plant seedlings in five kinds of typical secondary forests (Pinus tabulaeformis, Quercus valiena var. acuteserrata, Betula albo-sinensis, Picea asperata, and Pinus armandii) in Qinling Mountains. There was an obvious species differentiation of woody plant seedlings and saplings in the forests. Except for Q. valiena var. acuteserrata and P. armandii forests, the similarity coefficient of the seedlings and saplings species in the forests was lower. The seedlings and saplings quantity, species richness index, Simpson dominance index, and evenness index were higher in P. tabulaeformis and Q. valiena var. acuteserrata forests, the lowest in B. albo-sinensis forest, and basically the same in P. asperata and P. armandii forests. The percentages of the seedlings and saplings in the five forests had significant differences (P < 0.05). Except in B. albo-sinensis forest where the percentage of the saplings was higher, the percentage of the seedlings in the other stands was larger, and in the order of P. asperata forest > P. tabulaeformis forest > Q. valiena var. acuteserrata forest > P. armandii forest, respectively. The sprouting percentage of the seedlings in different forests had significant difference (P < 0.05), and was in the sequence of P. armandii forest > P. asperata forest > B. albo-sinensis forest > Q. valiena var. acuteserrata forest > P. tabulaeformis forest. In Q. valiena var. acuteserrata and P. tabulaeformis forests, the percentage of tree seedlings was the highest, occupying 68% and 51.4% of the total number of woody seedlings, respectively, and their communities were in the medium succession period, with a stronger persistent regeneration capability; in P. asperata and P. armandii forests, the percentage of tree seedlings was 40% and 15%, respectively, and their communities were in the late succession period, with a rather poor regeneration capability

  3. Effects of woody vegetation on overbank sand transport during a large flood, Rio Puerco, New Mexico

    USGS Publications Warehouse

    Griffin, Eleanor R.; Perignon, Mariela C.; Friedman, Jonathan M.; Tucker, Gregory E.

    2014-01-01

    Distributions of woody vegetation on floodplain surfaces affect flood-flow erosion and deposition processes. A large flood along the lower Rio Puerco, New Mexico, in August 2006 caused extensive erosion in a reach that had been sprayed with herbicide in September 2003 for the purpose of saltcedar (Tamarix spp.) control. Large volumes of sediment, including a substantial fraction of sand, were delivered to the reach downstream, which had not been treated with herbicide. We applied physically based, one-dimensional models of flow and suspended-sediment transport to compute volume concentrations of sand in suspension in floodplain flow at a site within the sprayed reach and at a site downstream from the sprayed reach. We computed the effects of drag on woody stems in reducing the skin friction shear stress, velocity of flow, and suspended-sand transport from open paths into patches of dense stems. Total flow and suspended-sand fluxes were computed for each site using well-constrained flood-flow depths, water-surface slopes, and measured shrub characteristics. Results show that flow in open paths carried high concentrations of sand in suspension with nearly uniform vertical distributions. Drag on woody floodplain stems reduced skin friction shear stresses by two orders of magnitude, yet sufficient velocities were maintained to transport sand more than 50 m into fields of dense, free-surface-penetrating stems. An increase in shrub canopy extent from 31% in the sprayed reach site to 49% in the downstream site was found to account for 69% of the computed decrease in discharge between the two sites. The results demonstrate the need to compute the spatial distribution of skin friction shear stress in order to effectively compute suspended-sand transport and to predict the fate of sediment and contaminants carried in suspension during large floods.

  4. Growing stock and woody biomass assessment in Asola-Bhatti Wildlife Sanctuary, Delhi, India.

    PubMed

    Kushwaha, S P S; Nandy, S; Gupta, Mohini

    2014-09-01

    Biomass is an important entity to understand the capacity of an ecosystem to sequester and accumulate carbon over time. The present study, done in collaboration with the Delhi Forest Department, focused on the estimation of growing stock and the woody biomass in the so-called lungs of Delhi--the Asola-Bhatti Wildlife Sanctuary in northern Aravalli hills. The satellite-derived vegetation strata were field-inventoried using stratified random sampling procedure. Growing stock was calculated for the individual sample plots using field data and species-specific volume equations. Biomass was estimated from the growing stock and the specific gravity of the wood. Among the four vegetation types, viz. Prosopis juliflora, Anogeissus pendula, forest plantation and the scrub, the P. juliflora was found to be the dominant vegetation in the area, covering 23.43 km(2) of the total area. The study revealed that P. juliflora forest with moderate density had the highest (10.7 m(3)/ha) while A. pendula forest with moderate density had the lowest (3.6 m(3)/ha) mean volume. The mean woody biomass was also found to be maximum in P. juliflora forest with moderate density (10.3 t/ha) and lowest in A. pendula forest with moderate density (3.48 t/ha). The total growing stock was estimated to be 20,772.95 m(3) while total biomass worked out to be 19,366.83 t. A strong correlation was noticed between the normalized difference vegetation index (NDVI) and the growing stock (R(2) = 0.84)/biomass (R(2) = 0.88). The study demonstrated that growing stock and the biomass of the woody vegetation in Asola-Bhatti Wildlife Sanctuary could be estimated with high accuracy using optical remote sensing data.

  5. Effect of woody-plant encroachment on livestock production in North and South America.

    PubMed

    Anadón, José D; Sala, Osvaldo E; Turner, B L; Bennett, Elena M

    2014-09-02

    A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social-economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km(2). Mean LP in the United States is 27 Rc per km(2), so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP.

  6. Industry/government collaborations on short-rotation woody crops for energy, fiber and wood products

    SciTech Connect

    Wright, L.L.; Berg, S.

    1996-12-31

    More than twenty-five organizations can be identified in the US and Canada that have research plantings of 20 ha in size or greater of short-rotation woody crops and most of those are well-established forest products companies. In 1990, only 9 forest products companies had commercial or substantial research plantings of short-rotation woody crops. The recent harvest and use of hybrid poplars for pulp and paper production in the Pacific Northwest has clearly stimulated interest in the use of genetically superior hybrid poplar clones across North America. Industry and government supported research cooperatives have been formed to develop sophisticated techniques for producing genetically superior hybrid poplars and willows suited for a variety of locations in the US. While the primary use of commercially planted short-rotation woody crops is for pulp and paper, energy is a co-product in most situations. A document defining a year 2020 technology vision for America`s forest, wood and paper industry affirms that {open_quotes}biomass will be used not only for building materials and paper and paperboard products, but also increasingly for steam, power, and liquid fuel production.{close_quotes} To accomplish the goals of {open_quotes}Agenda 2020{close_quotes} a new collaborative research effort on sustainable forestry has been initiated by the Department of Energy (DOE) and the American Forest and Paper Association (AF&PA). Both the new and old collaborative efforts are focusing on achieving substantial and sustainable gains in U.S. wood production for both energy and traditional wood products. AF&PA and DOE hope that industry and government partnerships addressing the competitiveness and energy efficiency of U.S. industries, can serve as a model for future research efforts.

  7. Biomass Increases Go under Cover: Woody Vegetation Dynamics in South African Rangelands

    PubMed Central

    Mograbi, Penelope J.; Knapp, David E.; Martin, Roberta E.; Main, Russell

    2015-01-01

    Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR) to measure aboveground biomass and subcanopy structure, as an explanatory tool to unravel vegetation dynamics in structurally heterogeneous landscapes. We sampled three communal rangelands in Bushbuckridge, South Africa, utilised by rural communities for fuelwood harvesting. Woody biomass estimates ranged between 9 Mg ha-1 on gabbro geology sites to 27 Mg ha-1 on granitic geology sites. Despite predictions of woodland depletion due to unsustainable fuelwood extraction in previous studies, biomass in all the communal rangelands increased between 2008 and 2012. Annual biomass productivity estimates (10–14% p.a.) were higher than previous estimates of 4% and likely a significant contributor to the previous underestimations of modelled biomass supply. We show that biomass increases are attributable to growth of vegetation <5 m in height, and that, in the high wood extraction rangeland, 79% of the changes in the vertical vegetation subcanopy are gains in the 1-3m height class. The higher the wood extraction pressure on the rangelands, the greater the biomass increases in the low height classes within the subcanopy, likely a strong resprouting response to intensive harvesting. Yet, fuelwood shortages are still occurring, as evidenced by the losses in the tall tree height class in the high extraction rangeland. Loss of large trees and gain in subcanopy shrubs could result in a structurally simple landscape with reduced functional capacity. This research demonstrates that intensive harvesting can, paradoxically, increase biomass and this has implications for the sustainability of ecosystem service provision. The structural implications of biomass increases in communal rangelands could be

  8. Biomass Increases Go under Cover: Woody Vegetation Dynamics in South African Rangelands.

    PubMed

    Mograbi, Penelope J; Erasmus, Barend F N; Witkowski, E T F; Asner, Gregory P; Wessels, Konrad J; Mathieu, Renaud; Knapp, David E; Martin, Roberta E; Main, Russell

    2015-01-01

    Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR) to measure aboveground biomass and subcanopy structure, as an explanatory tool to unravel vegetation dynamics in structurally heterogeneous landscapes. We sampled three communal rangelands in Bushbuckridge, South Africa, utilised by rural communities for fuelwood harvesting. Woody biomass estimates ranged between 9 Mg ha(-1) on gabbro geology sites to 27 Mg ha(-1) on granitic geology sites. Despite predictions of woodland depletion due to unsustainable fuelwood extraction in previous studies, biomass in all the communal rangelands increased between 2008 and 2012. Annual biomass productivity estimates (10-14% p.a.) were higher than previous estimates of 4% and likely a significant contributor to the previous underestimations of modelled biomass supply. We show that biomass increases are attributable to growth of vegetation <5 m in height, and that, in the high wood extraction rangeland, 79% of the changes in the vertical vegetation subcanopy are gains in the 1-3 m height class. The higher the wood extraction pressure on the rangelands, the greater the biomass increases in the low height classes within the subcanopy, likely a strong resprouting response to intensive harvesting. Yet, fuelwood shortages are still occurring, as evidenced by the losses in the tall tree height class in the high extraction rangeland. Loss of large trees and gain in subcanopy shrubs could result in a structurally simple landscape with reduced functional capacity. This research demonstrates that intensive harvesting can, paradoxically, increase biomass and this has implications for the sustainability of ecosystem service provision. The structural implications of biomass increases in communal rangelands could be

  9. Effect of woody-plant encroachment on livestock production in North and South America

    PubMed Central

    Anadón, José D.; Sala, Osvaldo E.; Turner, B. L.; Bennett, Elena M.

    2014-01-01

    A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social–economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km2. Mean LP in the United States is 27 Rc per km2, so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP. PMID:25136084

  10. Spatial and temporal patterns of beetles associated with coarse woody debris in managed bottomland hardwood forests.

    SciTech Connect

    Ulyshen, M., D.; Hanula, J., L.; Horn, S.; Kilgo, J., C.; Moorman, C., E.

    2004-05-13

    For. Ecol. and Mgt. 199:259-272. Malaise traps were used to sample beetles in artificial canopy gaps of different size (0.13 ha, 0.26 ha, and0.50 ha) and age in a South Carolina bottomland hardwood forest. Traps were placed at the center, edge, and in the surrounding forest of each gap. Young gaps (ý 1 year) had large amounts of coarse woody debris compared to the surrounding forest, while older gaps (ý 6 years) had virtually none. The total abundance and diversity of wood-dwelling beetles (Buprestidae, Cerambycidae, Brentidae, Bostrichidae, and Curculionidae (Scolytinae and Platypodinae)) was higher in the center of young gaps than in the center of old gaps. The abundance was higher in the center of young gaps than in the surrounding forest, while the forest surrounding old gaps and the edge of old gaps had a higher abundance and diversity of wood-dwelling beetles than did the center of old gaps. There was no difference in wood-dwelling beetle abundance between gaps of different size, but diversity was lower in 0.13 ha old gaps than in 0.26 ha or 0.50 ha old gaps. We suspect that gap size has more of an effect on woodborer abundance than indicated here because malaise traps sample a limited area. The predaceous beetle family Cleridae showed a very similar trend to that of the woodborers. Coarse woody debris is an important resource for many organisms, and our results lend further support to forest management practices that preserve coarse woody debris created during timber removal.

  11. Short rotation woody crops: Using agroforestry technology for energy in the United States

    SciTech Connect

    Wright, L L; Ranney, J W

    1991-01-01

    Agroforestry in the United States is being primarily defined as the process of using trees in agricultural systems for conservation purposes and multiple products. The type of agroforestry most commonly practiced in many parts of the world, that is the planting of tree crops in combination with food crops or pasture, is the type least commonly practiced in the United States. One type of agroforestry technique, which is beginning now and anticipated to expand to several million acres in the United States, is the planting of short-rotation woody crops (SRWCs) primarily to provide fiber and fuel. Research on SRWC's and environmental concerns are described.

  12. Managing coarse woody debris in forests of the Rocky Mountains. Forest Service research paper

    SciTech Connect

    Graham, R.T.; Harvey, A.E.; Jurgensen, M.F.; Jain, T.B.; Tonn, J.R.

    1994-09-01

    Recommendations for managing coarse woody debris after timber harvest were developed for 14 habitat types, ranging from ponderosa pine (Pinus ponderosa) habitat types of Arizona to subalpine fir (Abis lasiocarpa) habitat types of western Montana. Ectomycorrhizae were used as a bioindicator of health, productive forest soils. Undisturbed stands were studied to determine the optimum amounts of organic material for ectomycorrhizal activity. The management recommendations are intentionally conservative to ensure that enough organic matter is left after timber harvest to maintain long-term forest productivity.

  13. Short-Rotation Woody-Crops Program. Annual progress report for 1981

    SciTech Connect

    Ranney, J.W.; Cushman, J.H.

    1982-07-01

    This report is a summary of work sponsored by the US Department of Energy in the Short Rotation Woody Crops Program. The program is concerned with new wood production techniques that attain high productivity levels. Sometimes known as short rotation intensive culture, experimentation concentrated on hardwood tree species that stump sprout and can be re-harvested every 3 to 10 years. Research focused on the screening of fastgrowing species and techniques of short-rotation wood crop management, although plant propagation, new wood recovery systems, and economic evaluations are within the scope of the program. The program's objective is to attain high productivity rates at competitive prices.

  14. Environmental effects of growing short-rotation woody crops on former agricultural lands

    SciTech Connect

    Tolbert, V.R.; Thornton, F.C.; Joslin, J.D.

    1997-10-01

    Field-scale studies in the Southeast have been addressing the environmental effects of converting agricultural lands to biomass crop production since 1994. Erosion, surface water quality and quantity and subsurface movement of water and nutrients from woody crops, switchgrass and agricultural crops are being compared. Nutrient cycling, soil physical changes and crop productivity are also being monitored at the three sites. Maximum sediment losses occurred in the spring and fall. Losses were greater from sweetgum planted without a cover crop than with a cover crop. Nutrient losses of N and P in runoff and subsurface water occurred primarily after spring fertilizer application.

  15. Short rotation woody crops: Using agroforestry technology for energy in the United States

    SciTech Connect

    Wright, L.L.; Ranney, J.W.

    1991-12-31

    Agroforestry in the United States is being primarily defined as the process of using trees in agricultural systems for conservation purposes and multiple products. The type of agroforestry most commonly practiced in many parts of the world, that is the planting of tree crops in combination with food crops or pasture, is the type least commonly practiced in the United States. One type of agroforestry technique, which is beginning now and anticipated to expand to several million acres in the United States, is the planting of short-rotation woody crops (SRWCs) primarily to provide fiber and fuel. Research on SRWC`s and environmental concerns are described.

  16. Measurement of sap flow in roots of woody plants: a commentary.

    PubMed

    Burgess, S S; Adams, M A; Bleby, T M

    2000-07-01

    Measurements of sap flow in roots have recently been used to study patterns of resource acquisition by woody plants; however, the various thermometric methods employed have yielded disparate findings. These findings may be harmonized by accounting for the phenomenon of reverse sap flow in roots. We suggest that only methods capable of measuring slow and reverse rates of flow and that do not require assumptions of zero flow during the night are applicable to studies with roots. The heat ratio method and the constant power heat balance method fit these criteria, whereas the constant temperature heat balance, compensation heat pulse and thermal dissipation methods do not.

  17. The influence of coarse woody debris in the development of hydromorphic complexity within recently deglaciated streams

    NASA Astrophysics Data System (ADS)

    Klaar, M. J.; Hill, D. F.; Maddock, I.; Milner, A. M.

    2009-12-01

    The natural accumulation of logs, branches and other woody vegetation into the stream environment (coarse woody debris (CWD) accumulations) from adjacent stream banks plays an important role in altering the physical and ecological behaviour of rivers. CWD is often used as a tool in restoration projects to create or enhance instream habitat for biota. Research focussing on the influence of CWD characteristics on the three-dimensional flow structure surrounding accumulations, and quantification of the resultant changes in hydraulic and geomorphic composition is generally lacking. Rapid glacial recession within Glacier Bay National Park, Alaska has created the unique opportunity to study the development of a number of watersheds representing 200 years of development and varying degrees of CWD recruitment. Watershed age is related to its distance from the glacier termini, and thus temporal changes in habitat development can be studied on the basis of spatial differences. Size, position and dam properties of debris structures were mapped in order to monitor the long-term movement and formation of debris dams and associated geomorphic and ecological response. The influence of CWD characteristics on the development of geomorphic diversity and hydraulic variability were assessed using detailed habitat mapping and hydraulic assessment using an Acoustic Doppler Current Profiler at a number of transects upstream, downstream and adjacent to woody debris structures. Debris characteristics were found to alter across the watersheds as a result of adjacent terrestrial floodplain development and the subsequent introduction of woody debris into the riverine environment as a result of bank erosion. Results showed that riparian vegetation must be of a sufficient stage of development to elicit significant change in the geomorphic and hydraulic composition of the stream. Increased habitat heterogeneity within older watersheds was linked to the presence of complex debris structures

  18. Hydrologic regime controls pattern and architecture of woody debris in mountain streams

    NASA Astrophysics Data System (ADS)

    Hempel, L. A.; Grant, G.; Lewis, S.

    2015-12-01

    One question that has received little attention in the literature on wood in rivers is the degree to which the pattern and architecture of woody debris accumulations reflect the hydrologic regime of those rivers. In this study we focus on how patterns of woody debris in mountain streams reflect the underlying flow regime by comparing wood loading, piece orientation, location, and jam architecture in spring- and runoff dominated streams with similar bioclimatic settings in the Cascade Range of the Pacific Northwest. A key aspect of spring-dominated streams is that flows are near constant and vary by less than a factor of 2 over the course of the year, rarely exceeding bankfull. In contrast, flow in highly variable runoff-dominated streams can vary by as much as two orders of magnitude. To compare wood accumulations in these two stream types, we took over 40 measurements for each piece of wood along four reaches in streams of similar size but different hydrologic regime. Differences in woody debris are so great that characteristics of woody debris can actually be a useful field indicator of overall flow regime. Wood in stable, spring-fed streams is largely immobile (83%), found as a single piece (67%) or as part of an open-fabric log jam (33%), and is near perpendicular to channel, indicating little movement since emplacement. In a real sense, wood becomes part of the channel and represents the dominant structural feature in these channels, accounting for a large fraction of total flow resistance and form drag. In contrast, the majority of wood in runoff-dominated streams is mobile (83%), has stripped bark (86%), occurs in densely-packed log jams (84%), and is found parallel or sub-parallel to the channel, all indicators of frequent fluvial transport. In these systems, wood moves through the channel quickly and is a much smaller component of total resistance. We conclude that wood patterning and mobility do reflect the degree of flow variability in a stream, and that

  19. Mind the bubbles: achieving stable measurements of maximum hydraulic conductivity through woody plant samples

    PubMed Central

    Espino, Susana; Schenk, H. Jochen

    2011-01-01

    The maximum specific hydraulic conductivity (kmax) of a plant sample is a measure of the ability of a plants’ vascular system to transport water and dissolved nutrients under optimum conditions. Precise measurements of kmax are needed in comparative studies of hydraulic conductivity, as well as for measuring the formation and repair of xylem embolisms. Unstable measurements of kmax are a common problem when measuring woody plant samples and it is commonly observed that kmax declines from initially high values, especially when positive water pressure is used to flush out embolisms. This study was designed to test five hypotheses that could potentially explain declines in kmax under positive pressure: (i) non-steady-state flow; (ii) swelling of pectin hydrogels in inter-vessel pit membranes; (iii) nucleation and coalescence of bubbles at constrictions in the xylem; (iv) physiological wounding responses; and (v) passive wounding responses, such as clogging of the xylem by debris. Prehydrated woody stems from Laurus nobilis (Lauraceae) and Encelia farinosa (Asteraceae) collected from plants grown in the Fullerton Arboretum in Southern California, were used to test these hypotheses using a xylem embolism meter (XYL'EM). Treatments included simultaneous measurements of stem inflow and outflow, enzyme inhibitors, stem-debarking, low water temperatures, different water degassing techniques, and varied concentrations of calcium, potassium, magnesium, and copper salts in aqueous measurement solutions. Stable measurements of kmax were observed at concentrations of calcium, potassium, and magnesium salts high enough to suppress bubble coalescence, as well as with deionized water that was degassed using a membrane contactor under strong vacuum. Bubble formation and coalescence under positive pressure in the xylem therefore appear to be the main cause for declining kmax values. Our findings suggest that degassing of water is essential for achieving stable and precise

  20. Landsat Based Woody Vegetation Loss Detection in Queensland, Australia Using the Google Earth Engine

    NASA Astrophysics Data System (ADS)

    Johansen, K.; Phinn, S. R.; Taylor, M.

    2014-12-01

    Land clearing detection and woody Foliage Projective Cover (FPC) monitoring at the state and national level in Australia has mainly been undertaken by state governments and the Terrestrial Ecosystem Research Network (TERN) because of the considerable expense, expertise, sustained duration of activities and staffing levels needed. Only recently have services become available, providing low budget, generalized access to change detection tools suited to this task. The objective of this research was to examine if a globally available service, Google Earth Engine Beta, could be used to predict woody vegetation loss with accuracies approaching the methods used by TERN and the government of the state of Queensland, Australia. Two change detection approaches were investigated using Landsat Thematic Mapper time series and the Google Earth Engine Application Programming Interface: (1) CART and Random Forest classifiers; and (2) a normalized time series of Foliage Projective Cover (FPC) and NDVI combined with a spectral index. The CART and Random Forest classifiers produced high user's and producer's mapping accuracies of clearing (77-92% and 54-77%, respectively) when detecting change within epochs for which training data were available, but extrapolation to epochs without training data reduced the mapping accuracies. The use of FPC and NDVI time series provided a more robust approach for calculation of a clearing probability, as it did not rely on training data but instead on the difference of the normalized FPC / NDVI mean and standard deviation of a single year at the change point in relation to the remaining time series. However, the FPC and NDVI time series approach represented a trade-off between user's and producer's accuracies. Both change detection approaches explored in this research were sensitive to ephemeral greening and drying of the landscape. However, the developed normalized FPC and NDVI time series approach can be tuned to provide automated alerts for large

  1. Solubilization and functionalization of sulfuric acid lignin generated during bioethanol production from woody biomass.

    PubMed

    Matsushita, Yasuyuki; Inomata, Toyoki; Hasegawa, Tatsuya; Fukushima, Kazuhiko

    2009-01-01

    Sulfuric acid lignin (SAL), which is formed as a by-product during the production of bioethanol from woody biomass, was solubilized and functionalized by hydrothermal reaction. SAL could be easily dissolved in an alkaline medium, especially sodium hydroxide solution, by this reaction. The soluble part of the reaction products (S-HSAL) could be dissolved at neutral pH. IR spectrometric analysis of SAL revealed that hydrophilic groups were introduced in it during the reaction. The dispersibility of S-HSAL was increased by sulfonation (SS-HSAL), and it was found to be an effective dispersant for gypsum paste.

  2. Biomass, production and woody detritus in an old coast redwood (Sequoia sempervirens) forest

    USGS Publications Warehouse

    Busing, R.T.; Fujimori, T.

    2005-01-01

    We examined aboveground biomass dynamics, aboveground net primary production (ANPP), and woody detritus input in an old Sequoia sempervirens stand over a three-decade period. Our estimates of aboveground biomass ranged from 3300 to 5800 Mg ha-1. Stem biomass estimates ranged from 3000 to 5200 Mg ha-1. Stem biomass declined 7% over the study interval. Biomass dynamics were patchy, with marked declines in recent tree-fall patches <0.05 ha in size. Larger tree-fall patches approaching 0.2 ha in size were observed outside the study plot. Our estimates of ANPP ranged from 6 to 14 Mg ha -1yr-1. Estimates of 7 to 10 Mg ha-1yr -1 were considered to be relatively accurate. Thus, our estimates based on long-term data corroborated the findings of earlier short-term studies. ANPP of old, pure stands of Sequoia was not above average for temperate forests. Even though production was potentially high on a per stem basis, it was moderate at the stand level. We obtained values of 797 m3 ha -1 and 262 Mg ha-1 for coarse woody detritus volume and mass, respectively. Fine woody detritus volume and mass were estimated at 16 m3 ha-1 and 5 Mg ha-1, respectively. Standing dead trees (or snags) comprised 7% of the total coarse detritus volume and 8% of the total mass. Coarse detritus input averaged 5.7 to 6.9 Mg ha -1yr-1. Assuming steady-state input and pool of coarse detritus, we obtained a decay rate constant of 0.022 to 0.026. The old-growth stand of Sequoia studied had extremely high biomass, but ANPP was moderate and the amount of woody detritus was not exceptionally large. Biomass accretion and loss were not rapid in this stand partly because of the slow population dynamics and low canopy turnover rate of Sequoia at the old-growth stage. Nomenclature: Hickman (1993). ?? Springer 2005.

  3. Cheap and Cheerful Stream Restoration - An Example of System Wide Woody Addition Treatment

    NASA Astrophysics Data System (ADS)

    Wheaton, J. M.; Bennett, S. N.; Bouwes, N.; Camp, R.

    2012-12-01

    Stream restoration has been plagued with high price tags, limited spatial extents, and questionable effectiveness in light of largely absent monitoring efforts. One prominent example is the placement of large woody debris (LWD) structures and engineered log jams that are frequently employed to promote heterogeneity of instream habitat. Ironically, many of these treatments attempt to lock in place and over-engineer the woody structures as opposed to allowing them to adjust and rearrange themselves as natural LWD would have. We are in the midst of a large scale restoration experiment using LWD to recover ESA-listed steelhead trout (Oncorhynchus mykiss) populations in the Asotin Creek Watershed of Southeast Washington. The project is an Intensively Monitored Watershed (IMW) where the restoration treatment and monitoring use a hierarchal staircase design maximizing the power to detect a population level response in steelhead. We are treating over 12 km of stream with enough LWD input (> 200 pieces per km) to mimic the historic background wood loading and encourage the stream to reshape and regularly rework itself leaving. We are using hundreds of structures we call DWS (dynamic woody structures), which generally consist of a series of wooden fence posts driven into the stream bed and complex LWD anchored between them to invoke a specific hydrogeomorphic response. The real advantage of these DWS are their cost. They can be installed quickly (15-30 minutes each) and cheaply (< $100/DWS); even in remote settings with a 2-3 person crew, hydraulic post pounder, very cheap materials, and avoiding impacts associated with operating heavy equipment. This allows us to install lots of the structures at high density (every 5-15 channel widths) over an entire stream system. We call this overall approach System Wide Woody Addition Treatment (SWWAT). In the long term, we hypothesize that the SWWAT will provide an intial input LWD that will become a part of study creeks which are more

  4. Benefits and detriments of deploying genetically engineered woody biomass crops. Final Report

    SciTech Connect

    1995-04-01

    In the decade ahead, genetic engineering techniques will supplement traditional selection and controlled breeding approaches. These techniques will be used to develop transgenic tree species that exhibit significantly improved productivity and commercially valuable characteristics. Utilities interested in economically viable biomass power systems and more efficient carbon sequestration can use this report to evaluate the opportunities and challenges associated with development and deployment of transgenic tree crops. The objective is to present the state of the technology in genetic engineering of woody biomass crops; to assess anticipated research priorities; and to consider the actual and perceived risks of deploying genetically engineered species.

  5. Spatial-structural analysis of leafless woody riparian vegetation for hydraulic considerations

    NASA Astrophysics Data System (ADS)

    Weissteiner, Clemens; Jalonen, Johanna; Järvelä, Juha; Rauch, Hans Peter

    2013-04-01

    Woody riparian vegetation is a vital element of riverine environments. On one hand woody riparian vegetation has to be taken into account from a civil engineering point of view due to boundary shear stress and vegetation drag. On the other hand it has to be considered from a river ecological point of view due to shadowing effects and as a source of organic material for aquatic habitats. In hydrodynamic and hydro-ecological studies the effects of woody riparian vegetation on flow patterns are usually investigated on a very detailed level. On the contrary vegetation elements and their spatial patterns are generally analysed and discussed on the basis of an integral approach measuring for example basal diameters, heights and projected plant areas. For a better understanding of the influence of woody riparian vegetation on turbulent flow and on river ecology, it is essential to record and analyse plant data sets on the same level of quality as for hydrodynamic or hydro-ecologic purposes. As a result of the same scale of the analysis it is possible to incorporate riparian vegetation as a sub-model in the hydraulic analysis. For plant structural components, such as branches on different topological levels it is crucial to record plant geometrical parameters describing the habitus of the plant on branch level. An exact 3D geometrical model of real plants allows for an extraction of various spatial-structural plant parameters. In addition, allometric relationships help to summarize and describe plant traits of riparian vegetation. This paper focuses on the spatial-structural composition of leafless riparia woddy vegetation. Structural and spatial analyses determine detailed geometric properties of the structural components of the plants. Geometrical and topological parameters were recorded with an electro-magnetic scanning device. In total, 23 plants (willows, alders and birches) were analysed in the study. Data were recorded on branch level, which allowed for the

  6. Use of Course Woody Debris by Cotton Mouse (Peromyscus gossypinus)in a Southeastern Pine Forest

    SciTech Connect

    T.S. McCay

    1999-03-22

    Course woody debris may be an important resource for many small mammals by providing protection and food sources. The author tracked cotton mice movements via radiotelemetry and powder in managed loblolly pine forests. Most day refuges for mice were associated with debris, including rotting stumps (69%), upturned root boles (14%) and under fallen logs (9%). Stumps used were more larger and more highly decomposed. Night time telemetry indicated that mice movements were more closely associated with the logs. Rooting stumps are an important resource for cotton mice.

  7. Thirty-eight years of autogenic, woody understory dynamics in a mature, temperature pine-oak forest

    SciTech Connect

    Cain, M.D.; Shelton, M.G.

    1995-12-31

    In 1935, 32 ha of a pine-hardwood forest were set aside from future timber management in southern Arkansas, U.S.A. Old-growth timber had been cut to a 36-cm stump diameter before 1915. During 38 years of assessment, no catastrophic disturbances occurred within the 32-ha forest. Although loblolly pine (Pinus taeda L.) and shortleaf pine (Pinus echinata Mill.) dominated the overstory (64% of basal area in 1954 and 63% in 1993), pines were absent from the understory in all but seedling size classes for the last 38 years. Woody understory diversity indices were essentially stable for 38 years, but the similarity of understory species tended to decline as the time between inventories increased. Relative importance values for woody understory species tended to increase for the more shade-tolerant genera and decrease for less tolerant genera. Survival and height growth for woody understory species were also found to be positively correlated with shade tolerance.

  8. Effects of rainfall intensity and intermittency on woody vegetation cover and deep soil moisture in dryland ecosystems

    NASA Astrophysics Data System (ADS)

    Zhang, Ding-Hai; Li, Xin-Rong; Zhang, Feng; Zhang, Zhi-Shan; Chen, Yong-Le

    2016-12-01

    Identifying the relationship between the stochastic daily rainfall regime and the dynamics of plants and soil moisture is fundamental for the sustainable management of dryland ecosystems in a context of global climate change. An eco-hydrological model that couples the dynamics of woody vegetation cover and deep soil moisture (typically with a depth interval of 30-150 cm) was used to investigate the effect of stochastic intensity and the intermittency of precipitation on soil moisture in this deep interval, which affects woody vegetation cover. Our results suggest that the precipitation intensity and intermittency play an important role in the dynamics of wood vegetation cover and deep soil moisture. In arid and semiarid regions, as the annual precipitation increased, the rate of woody vegetation cover increased as a power-law function, and the deep soil moisture increased exponentially. For a given annual rainfall, there were positive correlations between the rainfall intensity (or rainfall intermittency) and both the woody vegetation cover and deep soil moisture. The positive correlations between wood vegetation cover and both rainfall intensity and intermittency may decrease with increases in the precipitation intensity or precipitation intermittency. The positive correlations between deep soil moisture and both rainfall intensity and rainfall intermittency increase as the precipitation intensity or precipitation intermittency increases. Moreover, these positive correlations may increase with increases in the mean annual rainfall. Our results emphasize the importance of daily precipitation variations in controlling the responses of woody vegetation cover and deep soil moisture to climate variations in arid and semiarid regions. Our model can aid the understanding of rainfall processes and indicates that increases in rainfall intensity or rainfall intermittency may lead to an increase in woody vegetation cover and deep soil moisture given an invariable annual

  9. Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

    PubMed

    Vaughn, Nicholas R; Asner, Gregory P; Smit, Izak P J; Riddel, Edward S

    2015-01-01

    Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

  10. Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds

    PubMed Central

    Vaughn, Nicholas R.; Asner, Gregory P.; Smit, Izak P. J.; Riddel, Edward S.

    2015-01-01

    Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50–450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques. PMID:26660502

  11. Patterns of Woody Growth for Brazilian Savanna (Cerrado) Trees in the Cuiaba Basin and Pantanal of Mato Grosso, Brazil

    NASA Astrophysics Data System (ADS)

    Zappia, A. J.; Vourlitis, G. L.; Pinto-Jr, O. B.

    2015-12-01

    The Brazilian savanna, locally known as cerrado, is a major ecosystem that covers a vast majority of central Brazil. Little is known about how woody growth within the cerrado is affected by soil properties such as texture and/or nutrient availability. Thus, in this study we assessed the relationship between woody growth and soil properties in the Cuiaba Basin and Pantanal of Mato Grosso, Brazil. We sampled 4-5 vegetation stands in each site that varied in hydrology, soil type, and vegetation composition and structure, and measured diameter at breast height, wood density, and soil nutrient concentration and physical properties every 5-10 m along a 100 m long transect. We hypothesized that as tree diameter at breast height increases, annual tree growth rate will decrease and that woody carbon (C) storage will increase as a function of soil nutrient availability. Our preliminary data support our hypotheses. Tree growth rates declined with tree size in both the Cuiaba Basin and the Pantanal. Rates of woody C storage, both on a per tree basis (kgC tree-1 year-1) and on a per unit ground area basis (kgC m-2 year-1) were significantly positively correlated with soil extractable phosphorus (P), calcium (Ca), and clay content, while only woody C storage on a per tree basis was positively correlated with potassium (K), magnesium (Mg), and cation exchange capacity (CEC). These data suggest that rates of woody C storage in cerrado are nutrient limited, while correspondence between C storage and soil physical properties could indicate both nutrient and water limitations to C storage.

  12. Overcoming barriers to seedling regeneration during forest restoration on tropical pasture land and the potential value of woody weeds

    PubMed Central

    Elgar, Amelia T.; Freebody, Kylie; Pohlman, Catherine L.; Shoo, Luke P.; Catterall, Carla P.

    2014-01-01

    Combating the legacy of deforestation on tropical biodiversity requires the conversion to forest of large areas of established pasture, where barriers to native plant regeneration include competition with pasture grasses and poor propagule supply (seed availability). In addition, initial woody plants that colonise pasture are often invasive, non-native species whose ecological roles and management in the context of forest regeneration are contested. In a restoration experiment at two 0.64 ha sites we quantified the response of native woody vegetation recruitment to (1) release from competition with introduced pasture grasses, and (2) local facilitation of frugivore-assisted seed dispersal provided by scattered woody plants and artificial bird perches. Herbicide pasture grass suppression during 20 months caused a significant but modest increase in density of native woody seedlings, together with abundant co-recruitment of the prominent non-native pioneer wild tobacco (Solanum mauritianum). Recruitment of native species was further enhanced by local structure in herbicide-treated areas, being consistently greater under live trees and dead non-native shrubs (herbicide-treated) than in open areas, and intermediate under bird perches. Native seedling recruitment comprised 28 species across 0.25 ha sampled but was dominated by two rainforest pioneers (Homalanthus novoguineensis, Polyscias murrayi). These early results are consistent with the expected increase in woody vegetation recruitment in response to release from competitive and dispersive barriers to rainforest regeneration. The findings highlight the need for a pragmatic consideration of the ecological roles of woody weeds and the potential roles of “new forests” more broadly in accelerating succession of humid tropical forest across large areas of retired agricultural land. PMID:24904602

  13. Managing Semi-Arid Rangelands for Carbon Storage: Grazing and Woody Encroachment Effects on Soil Carbon and Nitrogen

    PubMed Central

    Yusuf, Hasen M.; Treydte, Anna C.; Sauerborn, Jauchim

    2015-01-01

    High grazing intensity and wide-spread woody encroachment may strongly alter soil carbon (C) and nitrogen (N) pools. However, the direction and quantity of these changes have rarely been quantified in East African savanna ecosystem. As shifts in soil C and N pools might further potentially influence climate change mitigation, we quantified and compared soil organic carbon (SOC) and total soil nitrogen (TSN) content in enclosures and communal grazing lands across varying woody cover i.e. woody encroachment levels. Estimated mean SOC and TSN stocks at 0–40 cm depth varied across grazing regimes and among woody encroachment levels. The open grazing land at the heavily encroached site on sandy loam soil contained the least SOC (30 ± 2.1 Mg ha-1) and TSN (5 ± 0.57 Mg ha-1) while the enclosure at the least encroached site on sandy clay soil had the greatest mean SOC (81.0 ± 10.6 Mg ha-1) and TSN (9.2 ± 1.48 Mg ha-1). Soil OC and TSN did not differ with grazing exclusion at heavily encroached sites, but were twice as high inside enclosure compared to open grazing soils at low encroached sites. Mean SOC and TSN in soils of 0–20 cm depth were up to 120% higher than that of the 21–40 cm soil layer. Soil OC was positively related to TSN, cation exchange capacity (CEC), but negatively related to sand content. Our results show that soil OC and TSN stocks are affected by grazing, but the magnitude is largely influenced by woody encroachment and soil texture. We suggest that improving the herbaceous layer cover through a reduction in grazing and woody encroachment restriction are the key strategies for reducing SOC and TSN losses and, hence, for climate change mitigation in semi-arid rangelands. PMID:26461478

  14. Woody tissue photosynthesis and its contribution to trunk growth and bud development in young plants.

    PubMed

    Saveyn, An; Steppe, Kathy; Ubierna, Nerea; Dawson, Todd E

    2010-11-01

    Stem photosynthesis can contribute significantly to woody plant carbon balance, particularly in times when leaves are absent or in 'open' crowns with sufficient light penetration. We explored the significance of woody tissue (stem) photosynthesis for the carbon income in three California native plant species via measurements of chlorophyll concentrations, radial stem growth, bud biomass and stable carbon isotope composition of sugars in different plant organs. Young plants of Prunus ilicifolia, Umbellularia californica and Arctostaphylos manzanita were measured and subjected to manipulations at two levels: trunk light exclusion (100 and 50%) and complete defoliation. We found that long-term light exclusion resulted in a reduction in chlorophyll concentration and radial growth, demonstrating that trunk assimilates contributed to trunk carbon income. In addition, bud biomass was lower in covered plants compared to uncovered plants. Excluding 100% of the ambient light from trunks on defoliated plants led to an enrichment in ¹³C of trunk phloem sugars. We attributed this effect to a reduction in photosynthetic carbon isotope discrimination against ¹³C that in turn resulted in an enrichment in ¹³C of bud sugars. Taken together our results reveal that stem photosynthesis contributes to the total carbon income of all species including the buds in defoliated plants.

  15. Inoculation of Woody Legumes with Selected Arbuscular Mycorrhizal Fungi and Rhizobia To Recover Desertified Mediterranean Ecosystems

    PubMed Central

    Herrera, M. A.; Salamanca, C. P.; Barea, J. M.

    1993-01-01

    Revegetation strategies, either for reclamation or for rehabilitation, are being used to recover desertified ecosystems. Woody legumes are recognized as species that are useful for revegetation of water-deficient, low-nutrient environments because of their ability to form symbiotic associations with rhizobial bacteria and mycorrhizal fungi, which improve nutrient acquisition and help plants to become established and cope with stress situations. A range of woody legumes used in revegetation programs, particularly in Mediterranean regions, were assayed. These legumes included both exotic and native species and were used in a test of a desertified semiarid ecosystem in southeast Spain. Screening for the appropriate plant species-microsymbiont combinations was performed previously, and a simple procedure to produce plantlets with optimized mycorrhizal and nodulated status was developed. The results of a 4-year trial showed that (i) only the native shrub legumes were able to become established under the local environmental conditions (hence, a reclamation strategy is recommended) and (ii) biotechnological manipulation of the seedlings to be used for revegetation (by inoculation with selected rhizobia and mycorrhizal fungi) improved outplanting performance, plant survival, and biomass development. PMID:16348838

  16. Integration of Shiitake cultivation and solid-state anaerobic digestion for utilization of woody biomass.

    PubMed

    Lin, Yunqin; Ge, Xumeng; Liu, Zhe; Li, Yebo

    2015-04-01

    Pretreatment technologies that can not only reduce the recalcitrance of woody biomass but also achieve a high benefit-cost ratio are desirable for bioenergy production from woody biomass. In this study, an integrated process was proposed and conducted by pretreating woodchips via Shiitake cultivation for improved methane yield during solid-state anaerobic digestion (SS-AD), and simultaneously producing mushrooms as a high-value co-product. Shiitake cultivation using woodchips as the main substrate ingredient obtained mushroom yields comparable to those using a commercial substrate. Enzymatic digestibility and cumulative methane yields (133-160 L kg(-1)VS during 62 days of SS-AD) of pretreated substrates (spent mushroom substrate) were at least 1.5 times as high as those of untreated woodchips. Compared to a sole SS-AD process, the integrated Shiitake cultivation/SS-AD process increased methane production and solid waste reduction per kilogram of woodchips by about 1.5 and 8 times, respectively.

  17. Woody plant diversity and structure of shade-grown-coffee plantations in northern Chiapas, Mexico.

    PubMed

    Soto-Pinto, L; Romero-Alvarado, Y; Caballero-Nieto, J; Segura Warnholtz, G

    2001-01-01

    Shade-grown coffee is an agricultural system that contains some forest-like characteristics. However, structure and diversity are poorly known in shade coffee systems. In 61 coffee-growers' plots of Chiapas, Mexico, structural variables of shade vegetation and coffee yields were measured, recording species and their use. Coffee stands had five vegetation strata. Seventy seven woody species mostly used as wood were found (mean density 371.4 trees per hectare). Ninety percent were native species (40% of the local flora), the remaining were introduced species, mainly fruit trees/shrubs. Diametric distribution resembles that of a secondary forest. Principal Coordinates Analysis grouped plots in four classes by the presence of Inga, however the majority of plots are diverse. There was no difference in equitability among groups or coffee yields. Coffee yield was 835 g clean coffee per shrub, or ca. 1,668 kg ha-1. There is a significant role of shade-grown coffee as diversity refuge for woody plants and presumably associated fauna as well as an opportunity for shade-coffee growers to participate in the new biodiversity-friendly-coffee market.

  18. The lignol approach to biorefining of woody biomass to produce ethanol and chemicals.

    PubMed

    Arato, Claudio; Pye, E Kendall; Gjennestad, Gordon

    2005-01-01

    Processes that produce only ethanol from lignocellulosics display poor economics. This is generally overcome by constructing large facilities having satisfactory economies of scale, thus making financing onerous and hindering the development of suitable technologies. Lignol Innovations has developed a biorefining technology that employs an ethanol-based organosolv step to separate lignin, hemicellulose components, and extractives from the cellulosic fraction of woody biomass. The resultant cellulosic fraction is highly susceptible to enzymatic hydrolysis, generating very high yields of glucose (>90% in 12-24 h) with typical enzyme loadings of 10-20 FPU (filter paper units)/g. This glucose is readily converted to ethanol, or possibly other sugar platform chemicals, either by sequential or simultaneous saccharification and fermentation. The liquor from the organosolv step is processed by well-established unit operations to recover lignin, furfural, xylose, acetic acid, and a lipophylic extractives fraction. The process ethanol is recovered and recycled back to the process. The resulting recycled process water is of a very high quality, low BOD5, and suitable for overall system process closure. Significant benefits can be attained in greenhouse gas (GHG) emission reductions, as per the Kyoto Protocol. Revenues from the multiple products, particularly the lignin, ethanol and xylose fractions, ensure excellent economics for the process even in plants as small as 100 mtpd (metric tonnes per day) dry woody biomass input a scale suitable for processing wood residues produced by a single large sawmill.

  19. Woody biomass and RPF gasification using reforming catalyst and calcium oxide.

    PubMed

    Kobayashi, Jun; Kawamoto, Katsuya; Fukushima, Ryutaro; Tanaka, Shingo

    2011-05-01

    This study focused on steam gasification and reforming of waste biomass using a reforming catalyst. The purpose of the study was to evaluate the durability of a commercial Ni reforming catalyst and the effect of CaO on the reforming behavior, and to clarify detailed factors of catalytic performance, as well as the effect of operating parameters on the characteristics of produced gas composition. Moreover, catalyst regeneration was carried out and the behavior of catalytic activity based on gas composition was investigated. Using a fluidized bed gasifier and a fixed bed reformer, gasification and reforming of waste biomass were carried out. Commercial Ni-based catalyst and calcined limestone (CaO) were applied to the reforming reaction. Temperature of the gasifier and reformer was almost 1023K. Ratio of steam to carbon in the feedstock [molmol(-1)] and equivalence ratio (i.e., ratio of actual to theoretical amount of oxygen) [-] were set at about 2 and 0.3, respectively. The feed rate of the feedstock into the bench-scale gasifier was almost 15kgh(-1). The results of waste biomass gasification confirmed the improvement in H(2) composition by the CO(2) absorption reaction using the reforming catalyst and CaO. In addition, CaO proved to be especially effective in decreasing the tar concentration in the case of woody biomass gasification. Catalytic activity was maintained by means of catalyst regeneration processing by hydrogen reduction after air oxidation when woody biomass was used as feedstock.

  20. Functional and phylogenetic diversity of woody plants drive herbivory in a highly diverse forest.

    PubMed

    Schuldt, Andreas; Assmann, Thorsten; Bruelheide, Helge; Durka, Walter; Eichenberg, David; Härdtle, Werner; Kröber, Wenzel; Michalski, Stefan G; Purschke, Oliver

    2014-05-01

    Biodiversity loss may alter ecosystem processes, such as herbivory, a key driver of ecological functions in species-rich (sub)tropical forests. However, the mechanisms underlying such biodiversity effects remain poorly explored, as mostly effects of species richness - a very basic biodiversity measure - have been studied. Here, we analyze to what extent the functional and phylogenetic diversity of woody plant communities affect herbivory along a diversity gradient in a subtropical forest. We assessed the relative effects of morphological and chemical leaf traits and of plant phylogenetic diversity on individual-level variation in herbivory of dominant woody plant species across 27 forest stands in south-east China. Individual-level variation in herbivory was best explained by multivariate, community-level diversity of leaf chemical traits, in combination with community-weighted means of single traits and species-specific phylodiversity measures. These findings deviate from those based solely on trait variation within individual species. Our results indicate a strong impact of generalist herbivores and highlight the need to assess food-web specialization to determine the direction of biodiversity effects. With increasing plant species loss, but particularly with the concomitant loss of functional and phylogenetic diversity in these forests, the impact of herbivores will probably decrease - with consequences for the herbivore-mediated regulation of ecosystem functions.

  1. EFFECT OF SITE ON BACTERIAL POPULATIONS IN THE SAPWOOD OF COARSE WOODY DEBRIS.

    SciTech Connect

    Porter, Emma, G.,; Waldrop, Thomas, A.; McElreath, Susan, D.; Tainter, Frank, H.

    1998-01-01

    Porter, Emma G., T.A. Waldrop, Susan D. McElreath, and Frank H. Tainter. 1998. Effect of site on bacterial populations in the sapwood of coarse woody debris. Pp. 480-484. In: Proc. 9th Bienn. South. Silv. Res. Conf. T.A. Waldrop (ed). USDA Forest Service, Southern Research Station. Gen. Tech. Rep. SRS-20. Abstract: Coarse woody debris (CWD) is an important structural component of southeastern forest ecosystems, yet little is known about its dynamics in these systems. This project identified bacterial populations associated with CWD and their dynamics across landscape ecosystem classification (LEC) units. Bolts of red oak and loblolly pine were placed on plots at each of three hydric, mesic, and xeric sites at the Savannah River Station. After the controls were processed, samples were taken at four intervals over a 16-week period. Samples were ground within an anaerobe chamber using nonselective media. Aerobic and facultative anaerobic bacteria were identified using the Biolog system and the anaerobes were identified using the API 20A system. Major genera isolated were: Bacillus, Buttiauxella, Cedecea, Enterobacter, Erwinia, Escherichia, Klebsiella, Pantoea, Pseudomonas, Serratia, and Xanthomonas. The mean total isolates were determined by LEC units and sample intervals. Differences occurred between the sample intervals with total isolates of 6.67, 13.33, 10.17, and 9.50 at 3, 6, 10, and 16 weeks, respectively. No significant differences in the numbers of bacteria isolated were found between LEC units.

  2. Modeling and Optimization of Woody Biomass Harvest and Logistics in the Northeastern United States

    NASA Astrophysics Data System (ADS)

    Hartley, Damon S.

    World energy consumption is at an all-time high and is projected to continue growing for the foreseeable future. Currently, much of the energy that is produced comes from non-renewable fossil energy sources, which includes the burden of increased greenhouse gas emissions and the fear of energy insecurity. Woody biomass is being considered as a material that can be utilized to reduce the burden caused by fossil energy. While the technical capability to convert woody biomass to energy has been known for a long period of time, the cost of the feedstock has been considered too costly to be implemented in a large commercial scale. Increasing the use of woody biomass as an energy source requires that the supply chains are setup in a way that minimizes cost, the locational factors that lead to development are understood, the facilities are located in the most favorable locations and local resource assessments can be made. A mixed integer linear programming model to efficiently configure woody biomass supply chain configurations and optimize the harvest, extraction, transport, storage and preprocessing of the woody biomass resources to provide the lowest possible delivered price. The characteristics of woody biomass, such as spatial distribution and low bulk density, tend to make collection and transport difficult as compared to traditional energy sources. These factors, as well as others, have an adverse effect on the cost of the feedstock. The average delivered cost was found to be between 64.69-98.31 dry Mg for an annual demand of 180,000 dry Mg. The effect of resource availability and required demand was examined to determine the impact that each would have on the total cost. The use of woody biomass for energy has been suggested as a way to improve rural economies through job creation, reduction of energy costs and regional development. This study examined existing wood using bio-energy facilities in the northeastern United States to define the drivers of

  3. Manipulation of Auxin Response Factor 19 affects seed size in the woody perennial Jatropha curcas

    PubMed Central

    Sun, Yanwei; Wang, Chunming; Wang, Ning; Jiang, Xiyuan; Mao, Huizhu; Zhu, Changxiang; Wen, Fujiang; Wang, Xianghua; Lu, Zhijun; Yue, Genhua; Xu, Zengfu; Ye, Jian

    2017-01-01

    Seed size is a major determinant of seed yield but few is known about the genetics controlling of seed size in plants. Phytohormones cytokinin and brassinosteroid were known to be involved in the regulation of herbaceous plant seed development. Here we identified a homolog of Auxin Response Factor 19 (JcARF19) from a woody plant Jatropha curcas and genetically demonstrated its functions in controlling seed size and seed yield. Through Virus Induced Gene Silencing (VIGS), we found that JcARF19 was a positive upstream modulator in auxin signaling and may control plant organ size in J. curcas. Importantly, transgenic overexpression of JcARF19 significantly increased seed size and seed yield in plants Arabidopsis thaliana and J. curcas, indicating the importance of auxin pathway in seed yield controlling in dicot plants. Transcripts analysis indicated that ectopic expression of JcARF19 in J. curcas upregulated auxin responsive genes encoding essential regulators in cell differentiation and cytoskeletal dynamics of seed development. Our data suggested the potential of improving seed traits by precisely engineering auxin signaling in woody perennial plants. PMID:28102350

  4. Functional and phylogenetic diversity of woody plants drive herbivory in a highly diverse forest

    PubMed Central

    Schuldt, Andreas; Assmann, Thorsten; Bruelheide, Helge; Durka, Walter; Eichenberg, David; Härdtle, Werner; Kröber, Wenzel; Michalski, Stefan G; Purschke, Oliver

    2014-01-01

    Biodiversity loss may alter ecosystem processes, such as herbivory, a key driver of ecological functions in species-rich (sub)tropical forests. However, the mechanisms underlying such biodiversity effects remain poorly explored, as mostly effects of species richness – a very basic biodiversity measure – have been studied. Here, we analyze to what extent the functional and phylogenetic diversity of woody plant communities affect herbivory along a diversity gradient in a subtropical forest.We assessed the relative effects of morphological and chemical leaf traits and of plant phylogenetic diversity on individual-level variation in herbivory of dominant woody plant species across 27 forest stands in south-east China.Individual-level variation in herbivory was best explained by multivariate, community-level diversity of leaf chemical traits, in combination with community-weighted means of single traits and species-specific phylodiversity measures. These findings deviate from those based solely on trait variation within individual species.Our results indicate a strong impact of generalist herbivores and highlight the need to assess food-web specialization to determine the direction of biodiversity effects. With increasing plant species loss, but particularly with the concomitant loss of functional and phylogenetic diversity in these forests, the impact of herbivores will probably decrease – with consequences for the herbivore-mediated regulation of ecosystem functions. PMID:24460549

  5. Morphological changes in woody stem of Prunus jamasakura under simulated microgravity

    NASA Technical Reports Server (NTRS)

    Yoneyama, Emi; Ishimoto-Negishi, Yoko; Sano, Yuzou; Funada, Ryo; Yamada, Mitsuhiro; Nakamura, Teruko

    2004-01-01

    When the four-week-old woody stem of Prunus jamasakura was grown under simulated microgravity condition on a three-dimensional clinostat, it bent at growth, and width of its secondary xylem decreased due to the reduction of fiber cell numbers and a smaller microfibril angle in the secondary cell wall, as reported in our previous paper. Gravity induces the development of the secondary xylem that supports the stem upward against the action of gravity. In this study, morphological changes of the tissues and cells were microscopically observed. Disorder was found in the concentric structure of tissues that organize the stem. The radial arrangement of the cells was also disturbed in the secondary xylem, and in the secondary phloem secondary cell walls of the bast fiber cells were undeveloped. These findings suggest that differentiation and development of the secondary xylem and the bast fiber cells are strongly controlled by terrestrial gravity. These tissue and cells functions to support the stem under the action of gravity. Furthermore, clinorotation induced disorder in the straight joint of vessel elements and the lattice-like structure of radial parenchyma cells, which is responsible for water transportation and storage, respectively. Gravity is an essential factor for keeping the division and differentiation normal in woody stem.

  6. Acoustic vibration analysis for utilization of woody plant in space environment

    NASA Astrophysics Data System (ADS)

    Chida, Yukari; Yamashita, Masamichi; Hashimoto, Hirofumi; Sato, Seigo; Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Motohashi, Kyohei; Sakurai, Naoki; Nakagawa-izumi, Akiko

    2012-07-01

    We are proposing to raise woody plants for space agriculture in Mars. Space agriculture has the utilization of wood in their ecosystem. Nobody knows the real tree shape grown under space environment under the low or micro gravitational conditions such as outer environment. Angiosperm tree forms tension wood for keeping their shape. Tension wood formation is deeply related to gravity, but the details of the mechanism of its formation has not yet been clarified. For clarifying the mechanism, the space experiment in international space station, ISS is the best way to investigate about them as the first step. It is necessary to establish the easy method for crews who examine the experiments at ISS. Here, we are proposing to investigate the possibility of the acoustic vibration analysis for the experiment at ISS. Two types of Japanese cherry tree, weeping and upright types in Prunus sp., were analyzed by the acoustic vibration method. Coefficient-of-variation (CV) of sound speed was calculated by the acoustic vibration analysis. The amount of lignin and decomposed lignin were estimated by both Klason and Py-GC/MS method, respectively. The relationships of the results of acoustic vibration analysis and the inner components in tested woody materials were investigated. After the experiments, we confirm the correlation about them. Our results indicated that the acoustic vibration analysis would be useful for determining the inside composition as a nondestructive method in outer space environment.

  7. Can antibrowsing defense regulate the spread of woody vegetation in arctic tundra?

    USGS Publications Warehouse

    Bryant, John P.; Joly, Kyle; Chapin, F. Stuart; DeAngelis, Donald L.; Kielland, Knut

    2014-01-01

    Global climate warming is projected to promote the increase of woody plants, especially shrubs, in arctic tundra. Many factors may affect the extent of this increase, including browsing by mammals. We hypothesize that across the Arctic the effect of browsing will vary because of regional variation in antibrowsing chemical defense. Using birch (Betula) as a case study, we propose that browsing is unlikely to retard birch expansion in the region extending eastward from the Lena River in central Siberia across Beringia and the continental tundra of central and eastern Canada where the more effectively defended resin birches predominate. Browsing is more likely to retard birch expansion in tundra west of the Lena to Fennoscandia, Iceland, Greenland and South Baffin Island where the less effectively defended non-resin birches predominate. Evidence from the literature supports this hypothesis. We further suggest that the effect of warming on the supply of plant-available nitrogen will not significantly change either this pan-Arctic pattern of variation in antibrowsing defense or the resultant effect that browsing has on birch expansion in tundra. However, within central and east Beringia warming-caused increases in plant-available nitrogen combined with wildfire could initiate amplifying feedback loops that could accelerate shrubification of tundra by the more effectively defended resin birches. This accelerated shrubification of tundra by resin birch, if extensive, could reduce the food supply of caribou causing population declines. We conclude with a brief discussion of modeling methods that show promise in projecting invasion of tundra by woody plants.

  8. Morphological changes in woody stem of Prunus jamasakura under simulated microgravity.

    PubMed

    Yoneyama, Emi; Ishimoto-Negishi, Yoko; Sano, Yuzou; Funada, Ryo; Yamada, Mitsuhiro; Nakamura, Teruko

    2004-03-01

    When the four-week-old woody stem of Prunus jamasakura was grown under simulated microgravity condition on a three-dimensional clinostat, it bent at growth, and width of its secondary xylem decreased due to the reduction of fiber cell numbers and a smaller microfibril angle in the secondary cell wall, as reported in our previous paper. Gravity induces the development of the secondary xylem that supports the stem upward against the action of gravity. In this study, morphological changes of the tissues and cells were microscopically observed. Disorder was found in the concentric structure of tissues that organize the stem. The radial arrangement of the cells was also disturbed in the secondary xylem, and in the secondary phloem secondary cell walls of the bast fiber cells were undeveloped. These findings suggest that differentiation and development of the secondary xylem and the bast fiber cells are strongly controlled by terrestrial gravity. These tissue and cells functions to support the stem under the action of gravity. Furthermore, clinorotation induced disorder in the straight joint of vessel elements and the lattice-like structure of radial parenchyma cells, which is responsible for water transportation and storage, respectively. Gravity is an essential factor for keeping the division and differentiation normal in woody stem.

  9. Morphological patterns of extrafloral nectaries in woody plant species of the Brazilian cerrado.

    PubMed

    Machado, S R; Morellato, L P C; Sajo, M G; Oliveira, P S

    2008-09-01

    Extrafloral nectaries are nectar-secreting structures that are especially common among the woody flora of the Brazilian cerrado, a savanna-like vegetation. In this study, we provide morphological and anatomical descriptions of extrafloral nectaries (EFNs) occurring on vegetative and reproductive organs of several plant species from the cerrado, and discuss their function and ecological relevance. We describe the morphology and anatomy of EFNs of 40 species belonging to 15 woody families using scanning electron microscopy and light microscopy. We categorise EFNs following a structural-topographical classification, and characterise the vascularised and complex nectaries, amorphous nectaries and secretory trichomes. Fabaceae, Bignoniaceae, Malpighiaceae and Vochysiaceae were the plant families with the majority of species having EFNs. Ten species possess more than one morphotype of gland structure. Observations and experimental field studies in the cerrado support the anti-herbivore role of EFN-gathering ants in this habitat. Additional morphological studies of EFNs-bearing plants, including other growth forms (e.g. herbs and lianas), are being undertaken and will hopefully cast further light on the ecological relevance of these glands in the cerrado, especially with respect to their attractiveness to multiple visitors.

  10. Efficacy of woody biomass and biochar for alleviating heavy metal bioavailability in serpentine soil.

    PubMed

    Bandara, Tharanga; Herath, Indika; Kumarathilaka, Prasanna; Hseu, Zeng-Yei; Ok, Yong Sik; Vithanage, Meththika

    2017-04-01

    Crops grown in metal-rich serpentine soils are vulnerable to phytotoxicity. In this study, Gliricidia sepium (Jacq.) biomass and woody biochar were examined as amendments on heavy metal immobilization in a serpentine soil. Woody biochar was produced by slow pyrolysis of Gliricidia sepium (Jacq.) biomass at 300 and 500 °C. A pot experiment was conducted for 6 weeks with tomato (Lycopersicon esculentum L.) at biochar application rates of 0, 22, 55 and 110 t ha(-1). The CaCl2 and sequential extractions were adopted to assess metal bioavailability and fractionation. Six weeks after germination, plants cultivated on the control could not survive, while all the plants were grown normally on the soils amended with biochars. The most effective treatment for metal immobilization was BC500-110 as indicated by the immobilization efficiencies for Ni, Mn and Cr that were 68, 92 and 42 %, respectively, compared to the control. Biochar produced at 500 °C and at high application rates immobilized heavy metals significantly. Improvements in plant growth in biochar-amended soil were related to decreasing in metal toxicity as a consequence of metal immobilization through strong sorption due to high surface area and functional groups.

  11. Transcriptional and Hormonal Regulation of Gravitropism of Woody Stems in Populus[OPEN

    PubMed Central

    Gerttula, Suzanne; Zinkgraf, Matthew; Lewis, Daniel R.; Brumer, Harry; Hart, Foster; Filkov, Vladimir

    2015-01-01

    Angiosperm trees reorient their woody stems by asymmetrically producing a specialized xylem tissue, tension wood, which exerts a strong contractile force resulting in negative gravitropism of the stem. Here, we show, in Populus trees, that initial gravity perception and response occurs in specialized cells through sedimentation of starch-filled amyloplasts and relocalization of the auxin transport protein, PIN3. Gibberellic acid treatment stimulates the rate of tension wood formation and gravibending and enhances tissue-specific expression of an auxin-responsive reporter. Gravibending, maturation of contractile fibers, and gibberellic acid (GA) stimulation of tension wood formation are all sensitive to transcript levels of the Class I KNOX homeodomain transcription factor-encoding gene ARBORKNOX2 (ARK2). We generated genome-wide transcriptomes for trees in which gene expression was perturbed by gravistimulation, GA treatment, and modulation of ARK2 expression. These data were employed in computational analyses to model the transcriptional networks underlying wood formation, including identification and dissection of gene coexpression modules associated with wood phenotypes, GA response, and ARK2 binding to genes within modules. We propose a model for gravitropism in the woody stem in which the peripheral location of PIN3-expressing cells relative to the cambium results in auxin transport toward the cambium in the top of the stem, triggering tension wood formation, while transport away from the cambium in the bottom of the stem triggers opposite wood formation. PMID:26410302

  12. Convergent production and tolerance among 107 woody species and divergent production between shrubs and trees.

    PubMed

    He, Wei-Ming; Sun, Zhen-Kai

    2016-02-08

    Green leaves face two fundamental challenges (i.e., carbon fixation and stress tolerance) during their lifespan. However, the relationships between leaf production potential and leaf tolerance potential have not been explicitly tested with a broad range of plant species in the same environment. To do so, we conducted a field investigation based on 107 woody plants grown in a common garden and complementary laboratory measurements. The values, as measured by a chlorophyll meter, were significantly related to the direct measurements of chlorophyll content on a leaf area basis. Area-based chlorophyll content was positively correlated with root surface area, whole-plant biomass, leaf mass per area (LMA), and force to punch. Additionally, LMA had a positive correlation with force to punch. Shrubs had a higher leaf chlorophyll content than trees; however, shrubs and trees exhibited a similar leaf lifespan, force to punch, and LMA. These findings suggest that the production potential of leaves and their tolerance to stresses may be convergent in woody species and that the leaf production potential may differ between shrubs and trees. This study highlights the possibility that functional convergence and divergence might be linked to long-term selection pressures and genetic constraints.

  13. The Effects of Coarse Woody Debris and Vegetation Structure on Avian Communities of Southeastern Loblolly Pine (Pinus taeda) Forests

    SciTech Connect

    Lohr, S.M.

    1999-09-01

    Avian community richness and abundance were compared among several treatments in which coarse woody debris was manipulated. Treatments included a control, all dead wood removed less than four inches, and all down wood less than four inches removed. Avian communities were compared during the winter and spring nesting periods. In general, no differences in community parameters were detected during the winter months. However, during the spring nesting season several species of cavity nesting species like woodpeckers were significantly reduced where all snags were removed. Diversity was highest on the control. In addition, the woody debris appeared to benefit several ground nesting species such as the Carolina wren.

  14. Distributed Modeling Reveals the Ecohydrological Dynamics Linked with Woody Plant Encroachment in the Sonoran Desert

    NASA Astrophysics Data System (ADS)

    Pierini, N. A.; Vivoni, E. R.; Anderson, C.; Saripalli, S.; Robles-Morua, A.

    2012-12-01

    Woody plant encroachment is an important issue facing semiarid ecosystems in the southwestern United States that is associated with grazing pressures, fire suppression, and the invasion of shrub species into historical grasslands. In this study, we present observational and distributed modeling activities conducted in two small rangeland watersheds of the Santa Rita Experimental Range, Arizona. This Sonoran Desert landscape is representative of the vegetation shift from grasslands to a woody savanna due to the encroachment of velvet mesquite (Prosopis velutina). The paired basins are similar in size and in close proximity, leading to equivalent meteorological and soil conditions. Nevertheless, they vary substantially in mesquite cover, with one basin having undergone a removal treatment several decades ago, while the other watershed represents the regional encroachment process. This distinction presents an excellent case study for analyzing the effects of mesquite encroachment on dryland ecohydrological dynamics. Observational datasets are obtained from a high-resolution environmental sensor network consisting of six rain gauges, twenty-one soil moisture and temperature profiles, five channel runoff flumes and an eddy covariance tower with a complete set of radiation, energy, carbon and water fluxes. In addition, high-resolution digital terrain models and image orthomosaics were obtained from a piloted aircraft with Light Detection and Ranging (LiDAR) measurements and an Unmanned Aerial Vehicle (UAV) with a digital camera. These two remote sensing platforms allowed characterizing the topography, stream network and plant species distributions at a high resolution (<1 m) in both basins. Using the sensor network, we present comparative analyses of watershed rainfall-runoff transformation in the paired basins, illustrating the role that mesquite trees have in runoff generation at the two outlet flumes. We further explore the impact of mesquite trees on the soil

  15. Responses to shading of naturalized and non-naturalized exotic woody species

    PubMed Central

    Feng, Yanhao; van Kleunen, Mark

    2014-01-01

    Background and Aims Recent studies have suggested that responses to shading gradients may play an important role in establishment success of exotic plants, but hitherto few studies have tested this. Therefore, a common-garden experiment was conducted using multiple Asian woody plant species that were introduced to Europe >100 years ago in order to test whether naturalized and non-naturalized species differ in their responses to shading. Specifically, a test was carried out to determine whether naturalized exotic woody species maintained better growth under shaded conditions, and whether they expressed greater (morphological and physiological) adaptive plasticity in response to shading, relative to non-naturalized species. Methods Nineteen naturalized and 19 non-naturalized exotic woody species were grown under five light levels ranging from 100 to 7 % of ambient light. For all plants, growth performance (i.e. biomass), morphological and CO2 assimilation characteristics were measured. For the CO2 assimilation characteristics, CO2 assimilation rate was measured at 1200 μmol m–2 s–1 (i.e. saturated light intensity, A1200), 50 μmol m–2 s–1 (i.e. low light intensity, A50) and 0 μmol m–2 s–1 (A0, i.e. dark respiration). Key Results Overall, the naturalized and non-naturalized species did not differ greatly in biomass production and measured morphological and CO2 assimilation characteristics across the light gradient. However, it was found that naturalized species grew taller and reduced total leaf area more than non-naturalized species in response to shading. It was also found that naturalized species were more capable of maintaining a high CO2 assimilation rate at low light intensity (A50) when grown under shading. Conclusions The results indicate that there is no clear evidence that the naturalized species possess a superior response to shading over non-naturalized species, at least not at the early stage of their growth. However, the higher CO2

  16. Controls upon microbial accessibility to soil organic matter following woody plant encroachment into grasslands

    NASA Astrophysics Data System (ADS)

    Creamer, C. A.; Boutton, T. W.; Filley, T. R.

    2009-12-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic matter (SOM) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and soil hydrology. To elucidate the controls upon microbial accessibility to SOM, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas A&M Agricultural Experimental Station La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, plant biopolymer chemistry in SOM, and microbial community structure were tracked. Respiration rates declined steadily over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total carbon was mineralized to CO2 throughout the incubation. After day 84 a significantly (p < 0.05) greater portion of carbon was mineralized from soils of older woody clusters (34-86 years) than from soils of younger clusters (14-23 years) and the native grassland. Approximately 80% of patterns seen in cumulative CO2 loss could be explained by the proportions of macro- and micro-aggregates within each soil, suggesting soil structure is a major controlling factor of respiration rates. Despite documented carbon accrual within La Copita soils due to WPE, we observed no evidence of enhanced carbon stabilization in these respiration experiments. In fact, a greater proportion of total carbon was lost from the soil of mature woody stands than from young stands, suggesting carbon accumulation observed with WPE may be due to greater input rates or microbial dynamics not captured in the laboratory incubation. A cluster approximately 34 years in age represents a transition point in WPE where respiration dynamics become distinct between grassland and wooded elements. By day 84 of the incubation CO2 respired from all soils was depleted with respect to bulk SOM (1.5 to 5‰) and this

  17. On the origin of the woody buckwheat Fagopyrum tibeticum (=Parapteropyrum tibeticum) in the Qinghai-Tibetan Plateau.

    PubMed

    Tian, Xinmin; Luo, Jian; Wang, Ailan; Mao, Kangshan; Liu, Jianquan

    2011-11-01

    Here we tested whether 'insular woodiness', a striking evolutionary pattern that commonly occurs on islands, has also appeared in QTP continental endemics. Parapteropyrum, a monotypic shrubby genus occurring in the central QTP, has been previously placed in the tribe Atraphaxideae of the family Polygonaceae, while all the other woody species of this tribe mainly occur in western and central Asia. We studied sequence variations of nuclear ITS (internal transcribed spacer) and cp (chloroplast) DNA (rbcL and accD) of this genus and the other ten genera. The constructed phylogenies based on ITS, cpDNA or a combination of both datasets, suggest that the woody Parapteropyrum is nested within and most likely evolved from the herbaceous Fagopyrum. We propose that the large-scale uplift of the QTP not only promoted continental species radiation, but also the secondary feature of woodiness in a few herbaceous lineages in response to strong selection pressures, similar to those acting on island flora. In addition, the confirmation of Parapteropyrum within Fagopyrum highlights its potential use as a new, perennial source of buckwheat.

  18. The impact of different grazing periods in dry grasslands on the expansive grass Arrhenatherum elatius L. and on woody species.

    PubMed

    Dostálek, Jiří; Frantík, Tomáš

    2012-04-01

    Dry grasslands are one of the most species rich and endangered types of vegetation in Europe. In the Czech Republic, dry grasslands are mainly of anthropogenic origin and were formed as a result of grazing after the clear-cutting of thermophilous oak woods. Gradual changes in the farming landscape throughout the 20th century, particularly in the 1960s, resulted in the abandonment of the relatively infertile habitats of dry grasslands. After abandonment, dry grasslands decline and degrade due to the gradual overgrowth of woody species and expansion of perennial tall grasses. In the year 2000, a grazing management program was introduced in the protected areas within the territory of Prague City to maintain the species diversity of dry grasslands. The responses of the expansive grass species, Arrhenatherum elatius L. and multiple woody species (especially, Prunus spinosa L.) to differences in grazing periods were monitored for over a decade. Grazing in spring through the end of June had the greatest impact on the reduction of A. elatius and woody species. Grazing in the height of summer through autumn did not reduce the cover of these plants, and may support the prosperity of both A. elatius and the woody species due to higher levels of nutrients.

  19. Woody plant encroachment into grasslands leads to accelerated erosion of previously stable organic carbon from dryland soils

    NASA Astrophysics Data System (ADS)

    Puttock, Alan; Dungait, Jennifer A. J.; Macleod, Christopher J. A.; Bol, Roland; Brazier, Richard E.

    2014-12-01

    Drylands worldwide are experiencing rapid and extensive environmental change, concomitant with the encroachment of woody vegetation into grasslands. Woody encroachment leads to changes in both the structure and function of dryland ecosystems and has been shown to result in accelerated soil erosion and loss of soil nutrients. Covering 40% of the terrestrial land surface, dryland environments are of global importance, both as a habitat and a soil carbon store. Relationships between environmental change, soil erosion, and the carbon cycle are uncertain. There is a clear need to further our understanding of dryland vegetation change and impacts on carbon dynamics. Here two grass-to-woody ecotones that occur across large areas of the southwestern United States are investigated. This study takes a multidisciplinary approach, combining ecohydrological monitoring of structure and function and a dual-proxy biogeochemical tracing approach using the unique natural biochemical signatures of the vegetation. Results show that following woody encroachment, not only do these drylands lose significantly more soil and organic carbon via erosion but that this includes significant amounts of legacy organic carbon which would previously have been stable under grass cover. Results suggest that these dryland soils may not act as a stable organic carbon pool, following encroachment and that accelerated erosion of carbon, driven by vegetation change, has important implications for carbon dynamics.

  20. Effects of fireplace use on forest vegetation and amount of woody debris in suburban forests in northwestern Switzerland.

    PubMed

    Hegetschweiler, K Tessa; van Loon, Nicole; Ryser, Annette; Rusterholz, Hans-Peter; Baur, Bruno

    2009-02-01

    Urban forests are popular recreation areas in Europe. Several of these temperate broad-leaved forests also have a high conservation value due to sustainable management over many centuries. Recreational activities, particularly the use of fireplaces, can cause extensive damage to soil, ground vegetation, shrubs, and trees. Firewood collection depletes woody debris, leading to a loss of habitat for specialized organisms. We examined the effects of fireplace use on forest vegetation and the amount of woody debris by comparing disturbed and control plots in suburban forests in northwestern Switzerland. At frequently used fireplaces, we found reduced species densities in the ground vegetation and shrub layer and changes in plant species composition due to human trampling within an area of 150-200 m(2). Picnicking and grilling also reduced the height and changed the age structure of shrubs and young trees. The amount of woody debris was lower in disturbed plots than in control plots. Pieces of wood with a diameter of 0.6-7.6 cm were preferentially collected by fireplace users. The reduction in woody debris volume extended up to a distance of 16 m from the fire ring, covering an area of 800 m(2) at each picnic site. In order to preserve the ecological integrity of urban forests and to maintain their attractiveness as important recreation areas, we suggest depositing logging residues to be used as firewood and to restrict visitor movements near picnic sites.

  1. Facilitation contributes to Mediterranean woody plant diversity but does not shape the diversity-productivity relationship along aridity gradients.

    PubMed

    Rey, Pedro J; Alcántara, Julio M; Manzaneda, Antonio J; Sánchez-Lafuente, Alfonso M

    2016-07-01

    The diversity-productivity relationship (humped-back model (HBM)) and the stress-gradient (SGH) hypotheses may be connected when productivity is limited primarily by aridity. We analytically connect both hypotheses and assess the contribution of facilitation to woody plant richness along the aridity gradient of the Western Mediterranean floristic region. We monitored regeneration niches of woody plants, obtaining rarefied species richness and plant relative interaction indices in 54 forests and scrublands in a 1750-km geographical range across Spain, Morocco and the Canary Islands. We verified the monotonic increase in facilitation with aridity postulated by SGH and the humped-shape pattern of species richness expected from HBM, which became manifest after expanding the aridity gradient or crossing vegetation types. Along the gradient, interaction balance turned into facilitation earlier in forest than in scrublands. The effects of aridity and interaction balance on species diversity were additive rather than interdependent. Facilitation is an important driver of woody species richness at macroecological scales because it added up to diversity in most sites, with enhanced contribution with increased stress. The HBM was not shaped by species interactions. Results suggest that facilitation may act in Mediterranean vegetation buffering against critical transitions between states allowing woody plant communities to cope with the rise in aridity expected with global warming.

  2. Higher β-diversity observed for herbs over woody plants is driven by stronger habitat filtering in a tropical understory.

    PubMed

    Murphy, Stephen J; Salpeter, Kara; Comita, Liza S

    2016-08-01

    Herbaceous plants are a key component of tropical forests. Previous work indicates that herbs contribute substantially to the species richness of tropical plant communities. However, the processes structuring tropical herb diversity, and how they contrast with woody communities, have been underexplored. Within the understory of a 50-ha forest dynamics plot in central Panama, we compared the diversity, distribution, and abundance of vascular herbaceous plants with woody seedlings (i.e., tree and lianas <1 cm DBH and ≥20 cm tall). Beta-diversity was calculated for each community using a null model approach. We then assessed the similarity in alpha and beta-diversity among herbs, tree seedlings, and liana seedlings. Strengths of habitat associations were measured using permutational ANOVA among topographic habitat-types. Variance partitioning was then used to quantify the amount of variation in species richness and composition explained by spatial and environmental variables (i.e., topography, soils, and shade) for each growth form. Species richness and diversity were highest for tree seedlings, followed by liana seedlings and then herbs. In contrast, beta-diversity was 16-127% higher for herbs compared to woody seedlings, indicating higher spatial variation in this stratum. We observed no correlation between local richness or compositional uniqueness of herbs and woody seedlings across sites, indicating that different processes control the spatial patterns of woody and herbaceous diversity and composition. Habitat associations were strongest for herbs, as indicated by greater compositional dissimilarity among habitat types. Likewise, environmental variables explained a larger proportion of the variation in species richness and composition for herbs than for woody seedlings (richness = 25%, 14%, 12%; composition = 25%, 9%, 6%, for herbs, trees, and lianas, respectively). These differences between strata did not appear to be due to differences in lifespan alone

  3. Woody biomass-based bioenergy development at the Atikokan Power Generating Station: Local perceptions and public opinions

    NASA Astrophysics Data System (ADS)

    Baten, Cassia Sanzida

    To tackle climate change, reduce air pollution and promote development of renewable energy, the Ontario government is investing in the conversion of the coal-based Atikokan Power Generating Station (APGS) in Atikokan, Ontario, to woody biomass feedstock. This research offers one of the first looks at the perspectives of different individuals and groups on converting woody biomass to energy. Using a combination of study instruments which include literature review, surveys, interviews with key informants, semi-structured interviews, and focus group discussions, this dissertation uses qualitative research to provide a picture of the public's opinions and attitudes towards the APGS biomass energy development. Given Ontario's huge and sustainably managed forest resource, woody biomass is expected to be a major component of renewable energy production in Ontario. The move towards renewable energy that replaces fossil fuels with woody biomass will have considerable socio-economic implications for local and First Nation communities living in and around the bioenergy power generating station. Findings indicate that there is wide support for biomass utilization at the APGS by local people, especially since the project would create sustainable employment. The connection of woody biomass-based energy generation and rural community development provides opportunities and challenges for Atikokan's economic development. Respondents identified economic, environmental and social barriers to biomass utilization, and emphasized trust and transparency as key elements in the successful implementation of the APGS project. As demand for woody biomass-based energy increases, special attention will be needed to ensure and maintain the social, economic and environmental sustainability of biomass use at the APGS. In this research, respondents' views about biomass utilization for energy mainly focused on forest-related issues rather than energy. In Atikokan much of the project's social

  4. Japanese flowering cherry tree as a woody plant candidate grown in space

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, K.; Yoshida, S.; Hashimoto, H.; Nyunoya, H.; Funada, R.; Katayama, T.; Suzuki, T.; Honma, T.; Nagatomo, M.; Nakamura, T.

    We are proposing to raise woody plant in space for several applications Japanese flowering cherry tree is a candidate to do wood science in space Mechanism of sensing gravity and controlling shape of tree has been studied quite extensively Cherry mutants associated with gravity are telling responsible plant hormones and molecular machinery for plant adaptation against action of gravity Space experiment using our wood model contribute to understand molecular and cellular process of gravitropism in plant Tree is considered to be an important member in space agriculture to produce excess oxygen wooden materials for constructing living environment and provide biomass for cultivating mushrooms and insects Furthermore trees and their flowers improve quality of life under stressful environment in outer space

  5. Estimating aboveground biomass for broadleaf woody plants and young conifers in Sierra Nevada, California forests.

    USGS Publications Warehouse

    McGinnis, Thomas W.; Shook, Christine D.; Keeley, Jon E.

    2010-01-01

    Quantification of biomass is fundamental to a wide range of research and natural resource management goals. An accurate estimation of plant biomass is essential to predict potential fire behavior, calculate carbon sequestration for global climate change research, assess critical wildlife habitat, and so forth. Reliable allometric equations from simple field measurements are necessary for efficient evaluation of plant biomass. However, allometric equations are not available for many common woody plant taxa in the Sierra Nevada. In this report, we present more than 200 regression equations for the Sierra Nevada western slope that relate crown diameter, plant height, crown volume, stem diameter, and both crown diameter and height to the dry weight of foliage, branches, and entire aboveground biomass. Destructive sampling methods resulted in regression equations that accurately predict biomass from one or two simple, nondestructive field measurements. The tables presented here will allow researchers and natural resource managers to easily choose the best equations to fit their biomass assessment needs.

  6. Estimating aboveground biomass for broadleaf woody plants and young conifers in Sierra Nevada, California, forests

    USGS Publications Warehouse

    McGinnis, T.W.; Shook, C.D.; Keeley, J.E.

    2010-01-01

    Quantification of biomass is fundamental to a wide range of research and natural resource management goals. An accurate estimation of plant biomass is essential to predict potential fire behavior, calculate carbon sequestration for global climate change research, assess critical wildlife habitat, and so forth. Reliable allometric equations from simple field measurements are necessary for efficient evaluation of plant biomass. However, allometric equations are not available for many common woody plant taxa in the Sierra Nevada. In this report, we present more than 200 regression equations for the Sierra Nevada western slope that relate crown diameter, plant height, crown volume, stem diameter, and both crown diameter and height to the dry weight of foliage, branches, and entire aboveground biomass. Destructive sampling methods resulted in regression equations that accurately predict biomass from one or two simple, nondestructive field measurements. The tables presented here will allow researchers and natural resource managers to easily choose the best equations to fit their biomass assessment needs.

  7. Bioleaching of heavy metal from woody biochar using Acidithiobacillus ferrooxidans and activation for adsorption.

    PubMed

    Wang, Buyun; Li, Cuiping; Liang, Hui

    2013-10-01

    A woody biochar which was the byproduct of gasification of sawdust was treated with bioleaching by Acidithiobacillus ferrooxidans. After bioleaching, most heavy metal was removed from biochar. Leaching efficiency of heavy metal was efficient in a wide pulp density range from 1% to 10% (w/v) and decreased only a little with the increase in pulp density. It made application of biochar free of heavy metal risk. Benefitting from the improvement in functional group composition and pore structure after bioleaching, adsorption capacity of biochar to methylene blue and heavy metal was enhanced greatly. Adsorption of methylene blue could be described by pseudo-second-order model and Langmuir equation and the enhancement was mainly caused by the modification of physical character of biochar. Adsorption of heavy metal could be described by Freundlich equation and was mainly determined by chemical character of biochar.

  8. Integrated supply chain design for commodity chemicals production via woody biomass fast pyrolysis and upgrading.

    PubMed

    Zhang, Yanan; Hu, Guiping; Brown, Robert C

    2014-04-01

    This study investigates the optimal supply chain design for commodity chemicals (BTX, etc.) production via woody biomass fast pyrolysis and hydroprocessing pathway. The locations and capacities of distributed preprocessing hubs and integrated biorefinery facilities are optimized with a mixed integer linear programming model. In this integrated supply chain system, decisions on the biomass chipping methods (roadside chipping vs. facility chipping) are also explored. The economic objective of the supply chain model is to maximize the profit for a 20-year chemicals production system. In addition to the economic objective, the model also incorporates an environmental objective of minimizing life cycle greenhouse gas emissions, analyzing the trade-off between the economic and environmental considerations. The capital cost, operating cost, and revenues for the biorefinery facilities are based on techno-economic analysis, and the proposed approach is illustrated through a case study of Minnesota, with Minneapolis-St. Paul serving as the chemicals distribution hub.

  9. Interactions in the patterns of vegetative growth and reproduction in woody dioecious plants.

    PubMed

    Hoffmann, A J; Alliende, M C

    1984-01-01

    Interactions between vegetative growth and reproduction were evaluated in Peumus boldus, Lithraea caustica and Laretia acaulis, three woody dioecious species in central Chile. Phenological observations were made periodically on marked branches of male and female plants, and biomass allocation (dry weight) to vegetative and reproductive tissues was measured. The magnitude of flowering was evaluated in groups of plants in three successive seasons. The patterns of activities are species- and sex-dependent, and cycles of 2-4 years have been established. Branches that produce flowers either do not grow or grow less than branches without flowers, and males and females have differential resource allocation: male branches attain higher biomass values. Groups of plants show seasonal behavior that suggest synchrony in their reproductive activities.

  10. Rate of woody residue incorporation into Northern Rocky Mountain forest soils. Forest service research paper

    SciTech Connect

    Harvey, A.E.; Larsen, M.J.; Jurgensen, M.F.

    1981-08-01

    The important properties contributed to forest soils by decayed wood in the Northern Rocky Mountains make it desirable to determine the time required to reconstitute such materials in depleted soils. The ratio of fiber production potential (growth) to total quantity of wood in a steady state ecosystem provides estimates varying from approximately 100 to 300 years, depending on habitat type, for replacement of decayed soil wood. Radiocarbon dating of decayed wood in various stages of incorporation into the soil ranged from 100 to 550 years, depending on site and depth in soil. Species identification of decayed wood indicated that Douglas-fir residue is the most persistent woody material in these Northern Rocky Mountain soils.

  11. AIRSAR studies of woody shrub density in semiarid rangeland: Jornada del Muerto, New Mexico

    USGS Publications Warehouse

    Musick, H.B.; Schaber, G.S.; Breed, C.S.

    1998-01-01

    This study evaluates the use of polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data to assess woody shrub density in a semiarid site where the vegetation consists primarily of varied mixtures of herbaceous vegetation and shrubs. AIRSAR data and field observations of vegetation cover and growth form-composition were obtained for 59 sites in the Jornada del Muerto plain in southern New Mexico. Radar signature measures examined were C-, L- and P-band backscattering coefficients (??0) for HH, HV and W polarizations, ratios of ??0HH and ??0HV to ??0VV, and the HH-VV polarization phase difference and correlation coefficient. The most effective measure for estimation of shrub density was L-band ??0HV, which distinguished among shrub density classes with no misclassification. Sensitivity of this measure to small amounts of shrub cover was indicated by successful separation of sites with <1% shrub cover from sites with 1-5% cover. Separability of shrub density classes was generally least for C-band signature measures. A distinctive radar signature was exhibited by dense stands of Yucca elata, a semitreelike plant with uniformly thick ???10 cm diameter) fibrous stems. Yucca sites were distinguished from others by their high P-band ??0HV relative to L-band ??0HV. The results are largely explained by the greater sensitivity of lounger wavelengths to larger canopy structural elements. L-band ??0HV and other measures responsive to canopy volume scattering were more strongly related to shrub than to herbaceous plant cover because woody shrub canopies have numerous stems of the intermediate size to which L-band is most sensitive, whereas stems of this size are mostly lacking in herbaceous canopies. The uniform-diameter stems of yucca have larger dimensions to which P-band is more sensitive than L-band.This study evaluates the use of polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data to assess woody shrub density in a semiarid site where the vegetation consists

  12. Characterisation of seven Inocybe ectomycorrhizal morphotypes from a semiarid woody steppe.

    PubMed

    Seress, Diána; Dima, Bálint; Kovács, Gábor M

    2016-04-01

    Ectomycorrhizas (ECM) of Inocybe species (Inocybaceae, Basidiomycota) formed by three host plant species (Populus alba, Salix rosmarinifolia and Pinus nigra) in a semiarid woody steppe of Hungary were studied. To identify the fungal partners, we performed phylogenetic analyses of nucleotide sequences for the internal transcribed spacer region of nuclear DNA (nrDNA ITS) together with sequences gained from public databases. Seven Inocybe ectomycorrhiza morphotypes were morpho-anatomically characterised. Five morphotypes were identified (I. phaeoleuca, I. psammophila, I. semifulva, I. splendens and I. subporospora), whereas two morphotypes represented unidentified Inocybe species. Differences were discernible among the morphotypes, and they showed general anatomical characteristics of Inocybe ECM, such as the slightly organised plectenchymatic mantle (types A, B and E and the gelatinous C). The ECM of I. subporospora and I. phaeoleuca were detected from the introduced Pinus nigra. These two fungi are probably native to the area but capable of forming a novel ectomycorrhizal association with the invasive host.

  13. RESPONSE OF HERPETOFAUNA AND SORICIDS TO COARSE WOODY DEBRIS MANIPULATIONS IN UPLAND LOBLOLLY PINE STANDS.

    SciTech Connect

    Moseley, Kurtis, Rooks

    2004-06-01

    MS Thesis. University of Georgia, Athens, Georgia. 153 pp. Although use of coarse woody debris (CWD) by herpetofauna and shrew species has been well documented in the Pacific Northwest and southern Appalachian Mountain regions of the United States, little information exists regarding the importance of CWD to herpetofaunal and shrew assemblages in pine forests of the southeastern Coastal Plain. Furthermore, few manipulative studies have assessed response to increased CWD volume. The primary objective of my study was to assess the response of herpetofauna and shrews to CWD manipulations in upland loblolly pine (Pinus taeda) stands of the South Carolina Coastal Plain physiographic region as part of an interdisciplinary study undertaken to better understand the ecological role of CWD in southeastern pine forests.

  14. Prescribed fire and cutting as tools for reducing woody plant succession in a created salt marsh

    USGS Publications Warehouse

    Owens, A.B.; Proffitt, C.E.; Grace, J.B.

    2007-01-01

    This paper reports on efforts to reduce woody successional growth by the native shrub Iva frutescens L. in a created salt marsh by using prescribed fire and cutting. Experimental treatments included a winter burn, cutting plants at ground level, and a combination burn-and-cut treatment, with replicate plots of each. Iva frutescens proved to be extremely hardy, with zero mortality following the cutting, burning, or combination treatment; similar levels of regrowth were observed for all treatments. Individual shrub response, however, was found to be related to initial plant size, ground water level and salinity, and two fire characteristics (total heating >60??C and total heat index >60??C). Fire severity, sediment nutrient concentrations, and other abiotic factors had no observable effects. ?? 2007 Springer Science+Business Media B.V.

  15. Rapid and solvent-saving liquefaction of woody biomass using microwave-ultrasonic assisted technology.

    PubMed

    Lu, Zexiang; Wu, Zhengguo; Fan, Liwei; Zhang, Hui; Liao, Yiqiang; Zheng, Deyong; Wang, Siqun

    2016-01-01

    A novel process to rapidly liquefy sawdust using reduced quantities of solvent, was successfully carried out via microwave-ultrasonic assisted technology (MUAT) in a sulphuric acid/polyethylene glycol 400-glycerol catalytic system. The influences of some key parameters on the liquefaction yield were investigated. The results showed that compared with traditional liquefaction, the introduction of MUAT allowed the solvent dosage to be halved and shortened the liquefaction time from 60 to 20 min. The liquefaction yield reached 91% under the optimal conditions. However, the influence on the yield of some parameters such as catalyst concentration, was similar to that of traditional liquefaction, indicating that the application of MUAT possibly only intensified heat and mass transfer rather than altering either the degradation mechanism or pathway. The introduction of MUAT as a process intensification technology has good industrial application potential for woody biomass liquefaction.

  16. Use of wetlands for production of woody plants for fuels and petrochemical substitutes. [Alders, willows, poplars

    SciTech Connect

    Farnham, R.S.; Read, P.

    1981-03-01

    Work performed on this project in the past year has included the evaluations of natural stands productivity for wetland biomass species; propagation studies with alder, willow and poplar species; nursery establishment for production of cultivars and evaluation of wetland soils suitable for production of woody biomass species. Also a biomass research facility has been established in N. Minnesota suitable for long-term research and demonstration. Propagation research has included both micro and macro propagation techniques with native willows, selected willow clones from Sweden, alder seed selection from Finland and hybrid poplar clones from US Forest Service, Rhinelander, Wisconsin. Approximately 100,000 rooted plants will be available for field research by June 1, 1981.

  17. Woody vegetation of Sile and its environs (Istanbul Turkey) and destruction of the area.

    PubMed

    Sezer, Y; Altay, V; Ozyigit, I I; Yarci, C

    2015-01-01

    The woody vegetation of Sile district (Istanbul/Turkey), and its characteristics in conjunction with its environs are presented in this study. The field studies were performed using classic Braun-Blanquet method during 2003-2010 periods. In the present study three associations, two from forest vegetation and one from maquis vegetation, were characterized in the field. One of these associations is new and its description, typification and syntaxonomy was proposed. Phytosociological and phytoecological features of all three associations were compared with their relatives and related discussion was done accordingly. The associations described in the present study were as follows: Phillyreo-Lauretum nobilis, Smilaco-Castanetum sativae, Fago orientalis-Quercetum ibericae ass. nova. Furthermore, some soil properties such as saturation, organic matter, pH, CaCO, K2O and P2O5 were analyzed. Relationship between vegetations, their ecological characteristics and protection of these vegetations against biotic pressures are outlined in the present work.

  18. CosmoBon, tree research team, for studying utilization of woody plant in space environment

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, Kaori; Yamashita, Masamichi; Hashimoto, Hirofumi; Sato, Seigo; Baba, Keiichi; Chida, Yukari

    2012-07-01

    We are proposing to raise woody plants in space for several applications and plant science, as Tree research team, TRT. Trees produce excess oxygen, wooden materials for living cabin, and provide biomass for cultivating mushroom and insect as for the space agriculture. Excellent tree shapes which would be deeply related to wood formation improve quality of life under stressful environment in outer space. We have the serious problem about their size. Bonsai is one of the Japanese traditional arts. We have been investigating the tension wood formation under exotic gravitational environment using Bonsai. CosmoBon is the small tree Bonsai for our space experiment. The tension wood formation in CosmoBon was confirmed as the same as that in the natural trees. Our goal is to examine feasibility to grow various species of trees in space as bioresource for space agriculture.

  19. Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species

    PubMed Central

    Smith, Maria S.; Fridley, Jason D.; Yin, Jingjing; Bauerle, Taryn L.

    2013-01-01

    We examined the hydraulic properties of 82 native and non-native woody species common to forests of Eastern North America, including several congeneric groups, representing a range of anatomical wood types. We observed smaller conduit diameters with greater frequency in non-native species, corresponding to lower calculated potential vulnerability to cavitation index. Non-native species exhibited higher vessel-grouping in metaxylem compared with native species, however, solitary vessels were more prevalent in secondary xylem. Higher frequency of solitary vessels in secondary xylem was related to a lower potential vulnerability index. We found no relationship between anatomical characteristics of xylem, origin of species and hydraulic conductivity, indicating that non-native species did not exhibit advantageous hydraulic efficiency over native species. Our results confer anatomical advantages for non-native species under the potential for cavitation due to freezing, perhaps permitting extended growing seasons. PMID:24348490

  20. The complete plastid genome of Piper kadsura (Piperaceae), an East Asian woody vine.

    PubMed

    Lee, Jung-Hyun; Choi, In-Su; Choi, Byoung-Hee; Yang, Sungyu; Choi, Goya

    2016-09-01

    We sequenced the complete plastid genome (plastome) for Piper kadsura, a woody vine endemic to East Asia. This species is part of the largest genus within Piperaceae and its genome is almost identical to its congener P. cenocladum. The plastome for P. kadsura comprises 131 genes, including four unique rRNAs, 30 tRNAs, and 79 protein-coding genes. It retains ycf1 as an intact open reading frame. Our phylogenetic analysis demonstrated the monophyly of the Piper genus. The additional plastome sequence found in this evolutionarily and economically important genus will be a valuable, fundamental tool for future studies of phylogenetic relationships among basal angiosperms, and will provide a useful resource for molecular breeding programs.

  1. Demographic responses of shrews to removal of coarse woody debris in a managed pine forest.

    SciTech Connect

    McCay, Timothy, S.; Komoroski, Mark, J.

    2004-01-01

    McCay, T.S., and M.J. Komoroski. 2004. Demographic responses of shrews to removal of coarse woody debris in a managed pine forest. For. Ecol., and Mgt. 189:387-395. We trapped shrews at six 9.3 ha plots from which logs ý 10 cm diameter (coarse woody debris; CWD) had been manually removed and six control plots inmanaged loblolly pine (Pinus taeda) forests of the southeastern coastal plain, USA. Trapping was conducted seasonally between autumn 1997 and summer 2001. Capture rates of Cryptotis parva were lower at plots from which CWD was removed than at control plots (P ¡ 0ý011) and declined at all plots over the study period (P ¡ 0ý001). Capture rates of Blarina carolinensis (P ¡ 0ý129) and Sorex longirostris (P ¡ 0ý432) did not differ between removal and control plots, but declined over the study period (P ¡ 0ý001). Age distributions of B. carolinensis differed between removal and control plots (P ¡ 0ý048) with a smaller proportion of individuals in young age categories at removal plots. Sensitivity of Cryptotis to the removal of CWD may have been due to its sociality or low population density at the study area. A reduction in the abundance of young B. carolinensis after removal of CWD may reflect reduced reproduction and immigration of older individuals from outside the plot. Effect of removal of CWD on populations of these shrews was relatively weak compared to strong seasonal and multi-year variation in abundance. However, weak treatment effects may have been partly due to low ambient levels of CWD at control plots.

  2. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient

    NASA Astrophysics Data System (ADS)

    Niemeyer, Ryan J.; Heinse, Robert; Link, Timothy E.; Seyfried, Mark S.; Klos, P. Zion; Williams, Christopher J.; Nielson, Travis

    2017-01-01

    Woody plant cover has increased 10-fold over the last 140+ years in many parts of the semi-arid western USA. Woody plant cover can alter the timing and amount of plant available moisture in the soil and saprolite. To assess spatiotemporal subsurface moisture dynamics over two water years in a snow-dominated western juniper stand we compared moisture dynamics horizontally across a discontinuous canopy, and vertically in soil and saprolite. We monitored soil moisture at 15 and 60 cm and conducted periodic electromagnetic induction and electrical resistivity tomography surveys aimed at sensing moisture changes within the root zone and saprolite. Timing of soil moisture dry down at 15 cm was very similar between canopy patches and interspace. Conversely, dry down at 60 cm occurred 22 days earlier in the interspace than under canopy patches. After rainfall, interspaces with more shrubs showed greater increases in soil moisture than interspaces with few shrubs. For the few rainfall events that were large enough to increase soil moisture at 60 cm, increases in moisture occurred almost exclusively below the canopy. Soil water holding capacity from 0 to 150 cm was a primary driver of areas that were associated with the greatest change in distributed electrical conductivity - an indicator of changes in soil moisture - across the growing season. Vegetation was also correlated with a greater seasonal change in electrical conductivity at these depths. The seasonal change in resistivity suggested moisture extraction by juniper well into the saprolite, as deep as 12 m below the surface. This change in deep subsurface resistivity primarily occurred below medium and large juniper trees. This study suggests how tree roots are both increasing infiltration below their canopy while also extracting moisture at depths of upwards of 12 m. Information from this study can help improve our understanding of juniper resilience to drought and the hydrologic impacts of semi-arid land cover

  3. Effects of high-frequency understorey fires on woody plant regeneration in southeastern Amazonian forests

    PubMed Central

    Balch, Jennifer K.; Massad, Tara J.; Brando, Paulo M.; Nepstad, Daniel C.; Curran, Lisa M.

    2013-01-01

    Anthropogenic understorey fires affect large areas of tropical forest, yet their effects on woody plant regeneration post-fire remain poorly understood. We examined the effects of repeated experimental fires on woody stem (less than 1 cm at base) mortality, recruitment, species diversity, community similarity and regeneration mode (seed versus sprout) in Mato Grosso, Brazil. From 2004 to 2010, forest plots (50 ha) were burned twice (B2) or five times (B5), and compared with an unburned control (B0). Stem density recovered within a year after the first burn (initial density: 12.4–13.2 stems m−2), but after 6 years, increased mortality and decreased regeneration—primarily of seedlings—led to a 63 per cent and 85 per cent reduction in stem density in B2 and B5, respectively. Seedlings and sprouts across plots in 2010 displayed remarkable community similarity owing to shared abundant species. Although the dominant surviving species were similar across plots, a major increase in sprouting occurred—almost three- and fourfold greater in B2 and B5 than in B0. In B5, 29 species disappeared and were replaced by 11 new species often present along fragmented forest edges. By 2010, the annual burn regime created substantial divergence between the seedling community and the initial adult tree community (greater than or equal to 20 cm dbh). Increased droughts and continued anthropogenic ignitions associated with frontier land uses may promote high-frequency fire regimes that may substantially alter regeneration and therefore successional processes. PMID:23610167

  4. Photosynthetic and physiological responses of native and exotic tidal woody seedlings to simulated tidal immersion

    NASA Astrophysics Data System (ADS)

    Wu, Tonggui; Gu, Shenhua; Zhou, Hefeng; Wang, G. Geoff; Cheng, Xiangrong; Yu, Mukui

    2013-12-01

    Hibiscus hamabo, a native tidal woody species, and Myrica cerifera, an exotic tidal woody species, have been widely planted on coastal beaches in subtropical China. However, whether there are differences in physiological response and tolerance to immersion between the two tidal species is still unknown. Our objectives were to evaluate differences in the photosynthetic and physiological responses to tidal immersion for the two species in the context of sea level rise. With increasing immersion, net photosynthesis, stomatal conductance, intercellular CO2 concentration, and light saturation point declined progressively for both species, whereas dark respiration and light compensation point showed the reverse trend. Lower variation was observed in H. hamabo than in M. cerifera for each index in the same treatment. Photosynthetic ability and utilization of light, especially under high light intensity, decreased for both species. Leaf soluble sugar and protein contents, and glycolate oxidase activity first increased and then decreased with increasing of immersion degree, with the higher values observed in the W4 (4 h duration, 15 cm depth) and W6 (6 h duration, 25 cm depth) treatments for H. hamabo, and W2 (2 h duration, 5 cm depth) and W4 treatments for M. cerifera. These findings indicate that H. hamabo has a better ability to keep the reduction of photosynthesis at a minimum through soluble substance regulated osmotic potential and avoiding excess light damage to the photosynthetic system through increased photorespiration, heat dissipation, chlorophyll fluorescence. Our results suggest that H. hamabo is more tolerant to tidal immersion than M. cerifera, and therefore it is better adapted to the anticipated sea level rise in future.

  5. Caught in a fire trap: recurring fire creates stable size equilibria in woody resprouters.

    PubMed

    Grady, John M; Hoffmann, William A

    2012-09-01

    Globally, fire maintains many mesic habitats in an open canopy state by killing woody plants while reducing the size of those able to resprout. Where fire is frequent, tree saplings are often suppressed by a "fire trap" of repeated topkill (death of aerial biomoass) and resprouting, preventing them from reaching adult size. The ability to tolerate repeated topkill is an essential life-history trait that allows a sapling to persist until it experiences a long fire-free interval, during which it can escape the fire trap. We hypothesized that persistence in the fire trap results from a curvilinear relationship between pre-burn size and resprout size, which causes a plant to approach an equilibrial size in which post-fire biomass recovery is equal to fire-induced biomass loss. We also predicted that the equilibrial stem size is positively related to resource availability. To test these hypotheses, we collected data on pre-burn and resprout size of five woody plant species at wetland ecotones in longleaf pine savanna subjected to frequent burning. As expected, all species exhibited similar curvilinear relationships between pre-burn size and resprout size. The calculated equilibrial sizes were strong predictors of mean plant size across species and growing conditions, supporting the persistence equilibrium model. An alternative approach using matrix models yielded similar results. Resprouting was less vigorous in dry sites than at wet sites, resulting in smaller equilibrial stem sizes in drier sites; extrapolating these results provides an explanation for the absence of these species in xeric uplands. This new framework offers a straightforward approach to guide data collection for experimental, comparative, and modeling studies of plant persistence and community dynamics in frequently burned habitats.

  6. Modifying woody plants for efficient conversion to liquid and gaseous fuels

    SciTech Connect

    Dinus, R.J.; Dimmel, D.R.; Feirer, R.P.; Johnson, M.A.; Malcolm, E.W. )

    1990-07-01

    The Short Rotation Woody Crop Program (SRWCP), Department of Energy, is developing woody plant species as sources of renewable energy. Much progress has been made in identifying useful species, and testing site adaptability, stand densities, coppicing abilities, rotation lengths, and harvesting systems. Conventional plant breeding and intensive cultural practices have been used to increase above-ground biomass yields. Given these and foreseeable accomplishments, program leaders are now shifting attention to prospects for altering biomass physical and chemical characteristics, and to ways for improving the efficiency with which biomass can be converted to gaseous and liquid fuels. This report provides a review and synthesis of literature concerning the quantity and quality of such characteristics and constituents, and opportunities for manipulating them via conventional selection and breeding and/or molecular biology. Species now used by SRWCP are emphasized, with supporting information drawn from others as needed. Little information was found on silver maple (Acer saccharinum), but general comparisons (Isenberg 1981) suggest composition and behavior similar to those of the other species. Where possible, conclusions concerning means for and feasibility of manipulation are given, along with expected impacts on conversion efficiency. Information is also provided on relationships to other traits, genotype X environment interactions, and potential trade-offs or limitations. Biomass productivity per se is not addressed, except in terms of effects that may by caused by changes in constituent quality and/or quantity. Such effects are noted to the extent they are known or can be estimated. Likely impacts of changes, however effected, on suitability or other uses, e.g., pulp and paper manufacture, are notes. 311 refs., 4 figs., 9 tabs.

  7. Edge Effects Influence the Abundance of the Invasive Halyomorpha halys (Hemiptera: Pentatomidae) in Woody Plant Nurseries.

    PubMed

    Venugopal, P Dilip; Martinson, Holly M; Bergmann, Erik J; Shrewsbury, Paula M; Raupp, Michael J

    2015-06-01

    The invasive brown marmorated stink bug, Halyomorpha halys (Stål), has caused severe economic losses in the United States and is also a major nuisance pest invading homes. In diverse woody plant nurseries, favored host plants may be attacked at different times of the season and in different locations in the field. Knowledge of factors influencing H. halys abundance and simple methods to predict where H. halys are found and cause damage are needed to develop effective management strategies. In this study, we examined H. halys abundance on plants in tree nurseries as a function of distance from field edges (edge and core samples) and documented the abundance in tree nurseries adjoining different habitat types (corn, soybean, residential areas, and production sod). We conducted timed counts for H. halys on 2,016 individual trees belonging to 146 unique woody plant cultivars at two commercial tree nurseries in Maryland. Across three years of sampling, we found that H. halys nymphs and adults were more abundant at field edges (0-5 m from edges) than in the core of fields (15-20 m from edges). Proximity of soybean fields was associated with high nymph and adult abundance. Results indicate that monitoring efforts and intervention tactics for this invasive pest could be restricted to field edges, especially those close to soybean fields. We show clearly that spatial factors, especially distance from edge, strongly influence H. halys abundance in nurseries. This information may greatly simplify the development of any future management strategies.

  8. Carbon dynamics on agricultural land reverting to woody land in Ontario, Canada.

    PubMed

    Voicu, Mihai F; Shaw, Cindy; Kurz, Werner A; Huffman, Ted; Liu, Jiangui; Fellows, Max

    2017-02-21

    The 2015 Paris Agreement reinforces the importance of the land sector and its contribution to greenhouse gas (GHG) reductions. Thus, there is growing interest in improving estimates of the GHG balance in response to land-use changes (LUCs) involving agriculture and forestry, for national-scale reporting, and for carbon (C) offsets. Large agricultural areas in Europe, Russia and North America are reverting to forest, either naturally or through planting, after abandonment of agricultural land, and this trend may have a substantial impact on carbon budgets. We report results of a pilot project in the Mixedwood Plains ecozone of eastern Canada to analyze the change in the C budget on a landscape over 15 years on abandoned cropland where woody vegetation is regenerating. Thirty-six plots (2 km × 2 km) with paired aerial photographs taken circa 1994 and circa 2008 at a scale of 1:10,000 or larger were randomly selected from the 20 km × 20 km National Forest Inventory (NFI) grid. A spatially-explicit version of the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) was used to estimate impacts of LUC on C stocks and fluxes. Polygons identifying areas of LUC within each photo plot were delineated, classified, and evaluated to provide input data for the model. The rate of C accumulation in our study area was found to be relatively constant over the entire simulation period, at 1.07 Mg C/ha/yr. Abandoned agricultural land reverting to woody lands could play an important role in regional and national C sequestration in Canada, but more research is required to quantify the areal extent of this LUC.

  9. Allometric scaling relationship between above- and below-ground biomass within and across five woody seedlings.

    PubMed

    Cheng, Dongliang; Ma, Yuzhu; Zhong, Quanling; Xu, Weifeng

    2014-10-01

    Allometric biomass allocation theory predicts that leaf biomass (M L ) scaled isometrically with stem (M S ) and root (M R ) biomass, and thus above-ground biomass (leaf and stem) (M A ) and root (M R ) scaled nearly isometrically with below-ground biomass (root) for tree seedlings across a wide diversity of taxa. Furthermore, prior studies also imply that scaling constant should vary with species. However, litter is known about whether such invariant isometric scaling exponents hold for intraspecific biomass allocation, and how variation in scaling constants influences the interspecific scaling relationship between above- and below-ground biomass. Biomass data of seedlings from five evergreen species were examined to test scaling relationships among biomass components across and within species. Model Type II regression was used to compare the numerical values of scaling exponents and constants among leaf, stem, root, and above- to below-ground biomass. The results indicated that M L and M S scaled in an isometric or a nearly isometric manner with M R , as well as M A to M R for five woody species. Significant variation was observed in the Y-intercepts of the biomass scaling curves, resulting in the divergence for intraspecific scaling and interspecific scaling relationships for M L versus M S and M L versus M R , but not for M S versus M R and M A versus M R . We conclude, therefore, that a nearly isometric scaling relationship of M A versus M R holds true within each of the studied woody species and across them irrespective the negative scaling relationship between leaf and stem.

  10. Effects of Environment and Space on Species Turnover of Woody Plants across Multiple Forest Dynamic Plots in East Asia

    PubMed Central

    Chen, Yun; Yuan, Zhiliang; Li, Peikun; Cao, Ruofan; Jia, Hongru; Ye, Yongzhong

    2016-01-01

    Species turnover is fundamental for understanding the mechanisms that influence large-scale species richness patterns. However, few studies have described and interpreted large-scale spatial variation in plant species turnover, and the causes of this variation remain elusive. In addition, the determinants of species turnover depend on the dispersal ability of growth forms. In this study, we explored the large-scale patterns of woody species turnover across the latitude gradient based on eight large stem-mapping plots (covering 184 ha forest) in East Asia. The patterns of woody species turnover increased significantly with increasing latitude differences in East Asia. For overall woody species, environment explained 36.30, 37.20, and 48.48% of the total variance in Jaccard’s (βj), Sorenson’s, (βs), and Simpson’s dissimilarity (βsim). Spatial factors explained 47.92, 48.39, and 41.38% of the total variance in βj, βs, and βsim, respectively. The effects of pure spatial and spatially structured environments were stronger than pure environmental effects for overall woody species. Our results support the hypothesis that the effect of neutral processes on woody species turnover is more important than the effect of the environment. Neutral processes explained more variation for turnover of tree species, and environmental factors explained more variation for the turnover of shrub species on a large scale. Therefore, trees and shrubs should be subjected to different protection strategies in future biodiversity conservation efforts. PMID:27790236

  11. Determinants of water circulation in a woody bamboo species: afternoon use and night-time recharge of culm water storage.

    PubMed

    Yang, Shi-Jian; Zhang, Yong-Jiang; Goldstein, Guillermo; Sun, Mei; Ma, Ren-Yi; Cao, Kun-Fang

    2015-09-01

    To understand water-use strategies of woody bamboo species, sap flux density (Fd) in the culms of a woody bamboo (Bambusa vulgaris Schrader ex Wendland) was monitored using the thermal dissipation method. The daytime and night-time Fd were analyzed in the dry and rainy seasons. Additionally, diurnal changes in root pressure, culm circumference, and stomatal conductance (gs) were investigated to characterize the mechanisms used to maintain diurnal water balance of woody bamboos. Both in the dry and rainy seasons, daytime Fd responded to vapor pressure deficit (VPD) in an exponential fashion, with a fast initial increase in Fd when VPD increased from 0 to 1 kPa. The Fd and gs started to increase very fast as light intensity and VPD increased in the morning, but they decreased sharply once the maximum value was achieved. The Fd response of this woody bamboo to VPD was much faster than that of representative trees and palms growing in the same study site, suggesting its fast sap flow and stomatal responses to changes in ambient environmental factors. The Fd in the lower and higher culm positions started to increase at the same time in the morning, but the Fd in the higher culm position was higher than that of the lower culm in the afternoon. Consistently, distinct decreases in its culm circumference in the afternoon were detected. Therefore, unlike trees, water storage of bamboo culms was not used for its transpiration in the morning but in the afternoon. Nocturnal sap flow of this woody bamboo was also detected and related to root pressure. We conclude that this bamboo has fast sap flow/stomatal responses to irradiance and evaporative demands, and it uses substantial water storage for transpiration in the afternoon, while root pressure appears to be a mechanism resulting in culm water storage recharge during the night.

  12. Experimental tree removal in tallgrass prairie: variable responses of flora and fauna along a woody cover gradient.

    PubMed

    Alford, Aaron L; Hellgren, Eric C; Limb, Ryan; Engle, David M

    2012-04-01

    Woody plant encroachment is a worldwide phenomenon in grassland and savanna systems whose consequence is often the development of an alternate woodland state. Theoretically, an alternate state may be associated with changes in system state variables (e.g., species composition) or abiotic parameter shifts (e.g., nutrient availability). When state-variable changes are cumulative, such as in woody plant encroachment, the probability of parameter shifts increases as system feedbacks intensify over time. Using a Before-After Control-Impact (BACI) design, we studied eight pairs of grassland sites undergoing various levels of eastern redcedar (Juniperus virginiana) encroachment to determine whether responses of flora and fauna to experimental redcedar removal differed according to the level of pretreatment redcedar cover. In the first year after removal, herbaceous plant species diversity and evenness, woody plant evenness, and invertebrate family richness increased linearly with pretreatment redcedar cover, whereas increases in small-mammal diversity and evenness were described by logarithmic trends. In contrast, increases in woody plant diversity and total biomass of terrestrial invertebrates were accentuated at levels of higher pretreatment cover. Tree removal also shifted small-mammal species composition toward a more grassland-associated assemblage. During the second year postremoval, increases in herbaceous plant diversity followed a polynomial trend, but increases in most other metrics did not vary along the pretreatment cover gradient. These changes were accompanied by extremely high growing-season precipitation, which may have homogenized floral and faunal responses to removal. Our results demonstrate that tree removal increases important community metrics among grassland flora and fauna within two years, with some responses to removal being strongly influenced by the stage of initial encroachment and modulated by climatic variability. Our results underscore the

  13. Mapping global potential risk of mango sudden decline disease caused by fungus Ceratocystis fimbriata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mango Sudden Decline (MSD), sometimes referred to as mango wilt, is an important disease of mango caused by one of the most significant fungal species causing disease in woody plants, Ceratocystis fimbriata. This species is mainly disseminated by the mango bark beetle, Hypocryphalus mangiferae (Steb...

  14. Effects of termite activities on coarse woody debris decomposition in an intact lowland mixed dipterocarp forest of Brunei Darussalam

    NASA Astrophysics Data System (ADS)

    Lee, Sohye; Kim, Seungjun; Roh, Yujin; Abu Salim, Kamariah; Lee, Woo-Kyun; Davies, Stuart; Son, Yowhan

    2016-04-01

    Tropical forests have been considered important ecosystems in terms of carbon cycle and climate change, because they sequester carbon more than any other terrestrial ecosystems. In addition, coarse woody debris is one of the main carbon storages, accounting for 10 - 40% of the tropical forest carbon. Carbon in coarse woody debris is released by various activities of organisms, and particularly termite's feeding activities are known to be main process in tropical forests. Therefore, investigating the effects of termite activities on coarse woody debris decomposition is important to understanding carbon cycles of tropical forests. This study was conducted in an intact lowland mixed dipterocarp forest (MDF) of Brunei Darussalam, and three main MDF tree species (Dillenia beccariana, Macaranga bancana, and Elateriospermum tapos) were selected. Coarse woody debris samples of both 10 cm diameter and length were prepared, and half of samples were covered twice with nylon net (mesh size 1.5 mm × 1.5 mm) to prevent termite's approach. Three 2 m × 11 m permanent plots were installed in January, 2015 and eighteen samples per plot (3 species × 2 treatments × 3 repetitions) were placed at the soil surface. Weights of each sample were recorded at initial time, and weighed again in August, 2015. On average, uncovered and covered samples lost 18.9 % and 3.3 % of their initial weights, respectively. Weight loss percentage was highest in uncovered samples of M. bancana (23.9 %), and lowest in covered samples of E. tapos (7.8 %). Two-way ANOVA showed that tree species and termite exclusion treatment had statistically significant effects on coarse woody debris decomposition (P = 0.0001). The effect of species and termite exclusion treatment interaction was also statistically significant (P = 0.0001). The result reveals that termite activities promote the coarse woody debris decomposition and they influence differently along the wood species. However, many samples of D. beccariana

  15. Floodplain Stabilization by Woody Riparian Vegetation During an Extreme Flood Along Headwater Tributaries of East Plum Creek, Colorado.

    NASA Astrophysics Data System (ADS)

    Griffin, E. R.; Smith, J. D.

    2001-12-01

    Dense woody riparian vegetation acts to reduce flow velocities and boundary shear stresses on floodplain surfaces during large overbank flow events. Throughout the semi-arid west, woody riparian vegetation has been progressively thinned as the result of land use practices, such as grazing, and extensive reduction in beaver populations. Where woody vegetation is sparse, the floodplain surface is vulnerable to high rates of erosion during overbank flows. Unraveling of a floodplain surface occurs when flow is sufficiently deep and fast enough to erode the surface. Once erosion begins, it proceeds rapidly, leading to transformation from a narrow, single-threaded stream to a much wider, braided stream, as occurred along most of the mainstem of East Plum Creek, Colorado, during an extreme flood on June 16, 1965. Effects of this flood along headwater tributaries of East Plum Creek were documented in large scale (about 1:2,500) aerial photographs taken two days after the flood. The photographs along with available map information and field examination clearly show overbank flows were deep (on the order of 3 meters), yet the floodplain remained intact at sites with dense shrubs (sandbar willow). Two days after the flood, the shrubs were still lying bent over by the flood flow, and their canopy sizes and densities could be measured from the photographs. Within a 1.5-km reach, the downstream sequence of sites examined included: 1) locations where the floodplain surface and vegetation remained intact; 2) a location with less dense woody vegetation where the floodplain surface had just begun to erode; 3) locations with minimal woody vegetation, where the entire floodplain surface had begun to erode but a new channel had not yet formed; and 4) locations where erosion had caused a new, much wider channel to form and almost all pre-flood woody vegetation was removed. Estimates of pre-flood vegetation types and densities were made at each of these four sites. Boundary shear

  16. Evaluation of the Relative Merits of Herbaceous and Woody Crops for Use in Tunable Thermochemical Processing

    SciTech Connect

    Park, Joon-Hyun; Martinalbo, Ilya

    2011-12-01

    This report summarizes the work and findings of the grant work conducted from January 2009 until September 2011 under the collaboration between Ceres, Inc. and Choren USA, LLC. This DOE-funded project involves a head-to-head comparison of two types of dedicated energy crops in the context of a commercial gasification conversion process. The main goal of the project was to gain a better understanding of the differences in feedstock composition between herbaceous and woody species, and how these differences may impact a commercial gasification process. In this work, switchgrass was employed as a model herbaceous energy crop, and willow as a model short-rotation woody crop. Both crops are species native to the U.S. with significant potential to contribute to U.S. goals for renewable liquid fuel production, as outlined in the DOE Billion Ton Update (http://www1.eere.energy.gov/biomass/billion_ton_update.html, 2011). In some areas of the U.S., switching between woody and herbaceous feedstocks or blending of the two may be necessary to keep a large-scale gasifier operating near capacity year round. Based on laboratory tests and process simulations it has been successfully shown that suitable high yielding switchgrass and willow varieties exist that meet the feedstock specifications for large scale entrained flow biomass gasification. This data provides the foundation for better understanding how to use both materials in thermochemical processes. It has been shown that both switchgrass and willow varieties have comparable ranges of higher heating value, BTU content and indistinguishable hydrogen/carbon ratios. Benefits of switchgrass, and other herbaceous feedstocks, include its low moisture content, which reduce energy inputs and costs for drying feedstock. Compared to the typical feedstock currently being used in the Carbo-V® process, switchgrass has a higher ash content, combined with a lower ash melting temperature. Whether or not this may cause inefficiencies in the

  17. Co-occurring nonnative woody shrubs have additive and non-additive soil legacies.

    PubMed

    Kuebbing, Sara E; Patterson, Courtney M; Classen, Aimée T; Simberloff, Daniel

    2016-09-01

    To maximize limited conservation funds and prioritize management projects that are likely to succeed, accurate assessment of invasive nonnative species impacts is essential. A common challenge to prioritization is a limited knowledge of the difference between the impacts of a single nonnative species compared to the impacts of nonnative species when they co-occur, and in particular predicting when impacts of co-occurring nonnative species will be non-additive. Understanding non-additivity is important for management decisions because the management of only one co-occurring invader will not necessarily lead to a predictable reduction in the impact or growth of the other nonnative plant. Nonnative plants are frequently associated with changes in soil biotic and abiotic characteristics, which lead to plant-soil interactions that influence the performance of other species grown in those soils. Whether co-occurring nonnative plants alter soil properties additively or non-additively relative to their effects on soils when they grow in monoculture is rarely addressed. We use a greenhouse plant-soil feedback experiment to test for non-additive soil impacts of two common invasive nonnative woody shrubs, Lonicera maackii and Ligustrum sinense, in deciduous forests of the southeastern United States. We measured the performance of each nonnative shrub, a native herbaceous community, and a nonnative woody vine in soils conditioned by each shrub singly or together in polyculture. Soils conditioned by both nonnative shrubs had non-additive impacts on native and nonnative performance. Root mass of the native herbaceous community was 1.5 times lower and the root mass of the nonnative L. sinense was 1.8 times higher in soils conditioned by both L. maackii and L. sinense than expected based upon growth in soils conditioned by either shrub singly. This result indicates that when these two nonnative shrubs co-occur, their influence on soils disproportionally favors persistence

  18. The structure and function of roots of woody species on the Edwards Plateau, Texas, USA

    NASA Astrophysics Data System (ADS)

    Pockman, W. T.; McElrone, A. J.; Bleby, T. M.; Jackson, R. B.

    2008-05-01

    The Edwards Plateau in central Texas USA, supports woody vegetation in savannas and woodlands despite characteristically shallow soils. Surveys using caves to access greater depths have shown that roots of all dominant woody species can reach 7 m below the surface while some species reliably reach depths as great as 20 m. Comparative studies showed that deep roots were structurally distinct from shallow roots of similar diameter. Deep roots had larger xylem conducting elements resulting in more than 2-fold greater hydraulic conductance than their shallow counterparts. To understand the relationship between environmental fluctuations and deep root function in these species, we directly measured water transport in deep roots accessed via caves for comparison with similar measurements in shallow roots and stems. Long term measurements of Juniperus ashei, one of the most abundant species on the Edwards plateau, showed that the contribution of roots 7 m below the surface fluctuated with the volumetric water content (VWC) of surface soils. During prolonged drought, upward flow in deep roots accounted for as much as 60% of total daily transpiration and occurred not only during the day when the canopy was transpiring but also throughout the night when hydraulic redistribution from deep to shallow soil maintained flow through the roots. Hydraulic redistribution was suppressed immediately after precipitation until nocturnal flow gradually increased as VWC decreased. In a cave system where roots reach a stream 18-20 m below the surface, hydraulic redistribution was observed year-round in all measured individuals of three additional dominant species (Quercus fusiformis, Bumelia lanuginosa and Prosopis glandulosa). Like J. ashei, upward hydraulic redistribution was observed when surface soils were dry. More complex patterns of redistribution were also observed, including downward redistribution of soil water following precipitation, and continuing redistribution of soil water

  19. Transport, retention, and ecological significance of woody debris within a large ephemeral river

    USGS Publications Warehouse

    Jacobson, P.J.; Jacobson, K.M.; Angermeier, P.L.; Cherry, D.S.

    1999-01-01

    The spatiotemporal patterns and ecological significance of the retention of coarse particulate organic matter and large woody debris have been intensively studied in perennial rivers and streams but are virtually unknown in ephemeral systems. We examined the influence of 2 features characteristic of ephemeral systems, downstream hydrologic decay and in-channel tree growth, on the distribution, transport, and retention of woody debris following a flood having a ~2.6-y recurrence interval in the ephemeral Kuiseb River in southwestern Africa. A total of 2105 pieces of wood were painted at 8 sites along the river channel to measure retention patterns. The flood had a peak discharge of 159 m3/s at the upper end of the study area, decaying to <1 m3/s by 200 km downstream. Downstream export of wood from marking sites totaled 59.5% (n = 1253). Transport distances ranged from 1 to 124 km, and 34.8% (n = 436) of the exported wood was recovered. Marked wood retained within marking sites was significantly longer than exported wood (p < 0.001, t-test). Once in transport, there was little correlation between wood length and distance traveled (r = 0.11, correlation analysis, n = 369). Length influenced the site of retention; material retained on debris piles was significantly longer than that stranded on channel sediments (p < 0.001, t-test). In-channel growth of Faidherbia trees significantly influenced wood retention; 83.7% of marked wood not moved by the flood was associated with debris piles on Faidherbia trees. Similarly, 65% of the exported wood retained within downstream debris piles was associated with Faidherbia trees. In contrast to many perennial systems, we observed a general increase in wood retention downstream, peaking in the river's lower reaches in response to hydrologic decay. Debris piles induced sediment deposition and the formation of in-channel islands. Following flood recession, debris piles and their associated sediments provided moist, organic

  20. Physically-based modeling of drag force caused by natural woody vegetation

    NASA Astrophysics Data System (ADS)

    Järvelä, J.; Aberle, J.

    2014-12-01

    Riparian areas and floodplains are characterized by woody vegetation, which is an essential feature to be accounted for in many hydro-environmental models. For applications including flood protection, river restoration and modelling of sediment processes, there is a need to improve the reliability of flow resistance estimates. Conventional methods such as the use of lumped resistance coefficients or simplistic cylinder-based drag force equations can result in significant errors, as these methods do not adequately address the effect of foliage and reconfiguration of flexible plant parts under flow action. To tackle the problem, physically-based methods relying on objective and measurable vegetation properties are advantageous for describing complex vegetation. We have conducted flume and towing tank investigations with living and artificial plants, both in arrays and with isolated plants, providing new insight into advanced parameterization of natural vegetation. The stem, leaf and total areas of the trees confirmed to be suitable characteristic dimensions for estimating flow resistance. Consequently, we propose the use of leaf area index and leaf-to-stem-area ratio to achieve better drag force estimates. Novel remote sensing techniques including laser scanning have become available for effective collection of the required data. The benefits of the proposed parameterization have been clearly demonstrated in our newest experimental studies, but it remains to be investigated to what extent the parameter values are species-specific and how they depend on local habitat conditions. The purpose of this contribution is to summarize developments in the estimation of vegetative drag force based on physically-based approaches as the latest research results are somewhat dispersed. In particular, concerning woody vegetation we seek to discuss three issues: 1) parameterization of reconfiguration with the Vogel exponent; 2) advantage of parameterizing plants with the leaf area

  1. Soil respiration responses to variation in temperature and moisture availability under woody plants and grasses

    NASA Astrophysics Data System (ADS)

    Pravalprukskul, P.; Pavao-Zuckerman, M.; Barron-Gafford, G. A.

    2011-12-01

    Woody plant encroachment into grasslands, such as in the southwestern US, is thought to have altered regional carbon fluxes due to the differences in structure and function between grasses and woody plants. It is unknown how climate change predictions for such areas, particularly warmer temperatures and fewer but larger precipitation events, might further acerbate our ability to estimate flux dynamics. Soil respiration, a key flux affecting ecosystem carbon balance, has been increasingly studied, but the exact effects of temperature and precipitation changes on flux rates have not been fully determined, particularly their interactive effects. The goal of this study was to compare soil respiration responses to different temperatures in soils under native southwestern mesquites and grasses undergoing a precipitation pulse, whilst removing other confounding factors, such as soil history, through the controlled environments within Biosphere 2. Mesquites and grasses were transplanted into ground basalt within two environments maintained at a 4°C temperature difference, the projected temperature increase from climate change. Post-transplant soil samples were incubated between 10 and 40°C to determine the temperature sensitivities of soils from each microhabitat within a month of this transplant. A single-peak, best-fit model for grass soils suggested a weak temperature sensitivity, while mesquite soils showed little to no sensitivity. Additionally, all plants underwent a drought treatment prior to the precipitation event, and soil respiration rates were tracked over several days using the collar technique. This portion of the study allowed for an estimation of the sensitivity of soil respiration to precipitation pulses under a variety of antecedent moisture conditions. Initial results illustrate that soils under mesquites tend to respire significantly more than soil under grasses or in bare soils over the course of a precipitation event. Together, these results suggest

  2. Online induction heating for determination of isotope composition of woody stem water with laser spectrometry: A methods assessment

    USGS Publications Warehouse

    Lazarus, Brynne E.; Germino, Matthew; Vander Veen, Jessica L.

    2016-01-01

    Application of stable isotopes of water to studies of plant–soil interactions often requires a substantial preparatory step of extracting water from samples without fractionating isotopes. Online heating is an emerging approach for this need, but is relatively untested and major questions of how to best deliver standards and assess interference by organics have not been evaluated. We examined these issues in our application of measuring woody stem xylem of sagebrush using a Picarro laser spectrometer with online induction heating. We determined (1) effects of cryogenic compared to induction-heating extraction, (2) effects of delivery of standards on filter media compared to on woody stem sections, and (3) spectral interference from organic compounds for these approaches (and developed a technique to do so). Our results suggest that matching sample and standard media improves accuracy, but that isotopic values differ with the extraction method in ways that are not due to spectral interference from organics.

  3. Online induction heating for determination of isotope composition of woody stem water with laser spectrometry: a methods assessment.

    PubMed

    Lazarus, Brynne E; Germino, Matthew J; Vander Veen, Jessica L

    2016-06-01

    Application of stable isotopes of water to studies of plant-soil interactions often requires a substantial preparatory step of extracting water from samples without fractionating isotopes. Online heating is an emerging approach for this need, but is relatively untested and major questions of how to best deliver standards and assess interference by organics have not been evaluated. We examined these issues in our application of measuring woody stem xylem of sagebrush using a Picarro laser spectrometer with online induction heating. We determined (1) effects of cryogenic compared to induction-heating extraction, (2) effects of delivery of standards on filter media compared to on woody stem sections, and (3) spectral interference from organic compounds for these approaches (and developed a technique to do so). Our results suggest that matching sample and standard media improves accuracy, but that isotopic values differ with the extraction method in ways that are not due to spectral interference from organics.

  4. The most commonly available woody plant species are the most useful for human populations: a meta-analysis.

    PubMed

    Gonçalves, Paulo Henrique Santos; Albuquerque, Ulysses Paulino; Medeiros, Patrícia Muniz de

    2016-10-01

    An increasing number of studies have aimed to clarify the factors leading human groups to prioritize the use of some woody plant species compared to others. Some of these studies have tested the apparency hypothesis in aiming to understand this phenomenon. According to the apparency hypothesis, the most commonly available local plant species on a forest path are the most useful to that local human population. However, the sparse and diverse nature of the results from studies investigating the factors that influence human exploitation of plant resources motivated us to perform a meta-analysis on the apparency hypothesis. We searched in the main databases (Scopus, ScienceDirect, Google Scholar, and Scielo) for studies that correlated the environmental availability of woody species (estimated through vegetation parameters) with the degree of importance of such species to the local human population (estimated by means of the use value index). Overall, this meta-analysis supported the apparency hypothesis, although we also found high levels of heterogeneity in these studies. When the distinct uses of woody flora were considered separately, we found that local species availability is important for fuelwood (firewood and charcoal) and construction (houses, fences, etc.) purposes but does not explain medicinal and technological (object manufacture) plant use. We found no important differences in correlation values between the degree of species importance for people and the different vegetation parameters, although correlations are slightly higher for the dominance and importance value index. Our findings suggest that the exploitation of woody flora is influenced by local availability.

  5. Impacts of woody plant encroachment on regional climate in the southern Great Plains of the United States

    NASA Astrophysics Data System (ADS)

    Ge, Jianjun; Zou, Chris

    2013-08-01

    change can influence climate by altering the fluxes of mass and energy between ecosystems and the atmosphere. In the past century or so, rapid conversion of grasslands to woodland by woody species encroachment is one of the most important vegetation changes in the semiarid and arid regions of the world. The objective of this study is to investigate potential impacts of this widespread phenomenon on climate system in the southern Great Plains of the United States. The Regional Atmospheric Modeling System (RAMS) is used for this study. Grassland on the surface in RAMS is gradually replaced by woody species and RAMS is run a set of times, each with a different amount of encroachment. RAMS-simulated precipitation and air temperature are then analyzed. This study finds tha t over a 1 year period woody plant encroachment leads to increase in rainfall and the increase is statistically significant at many locations. Woody encroachment also has an overall warming effect, but increase in temperature is not statistically significant. Temperature and precipitation increase almost linearly with increasing encroachment on the surface. When grassland is completely replaced, annual accumulated precipitation increases by 23.6 mm and maximum air temperature rises by 0.13°C averaged over the entire study area. In areas where encroachment occurs, averaged increases in accumulated precipitation and temperature are 58.2 mm and 0.27°C, respectively. The largest increase in precipitation and strongest warming tend to be located in dry and encroached areas including central and northern Texas, and they reach as high as 213.6 mm and 0.68°C, respectively. Decrease in surface albedo is found to be the most important factor that causes these changes.

  6. Techno-Economic Analysis of Liquid Fuel Production from Woody Biomass via Hydrothermal Liquefaction (HTL) and Upgrading

    SciTech Connect

    Zhu, Yunhua; Biddy, Mary J.; Jones, Susanne B.; Elliott, Douglas C.; Schmidt, Andrew J.

    2014-09-15

    A series of experimental work was conducted to convert woody biomass to gasoline and diesel range products via hydrothermal liquefaction (HTL) and catalytic hydroprocessing. Based on the best available test data, a techno-economic analysis (TEA) was developed for a large scale woody biomass based HTL and upgrading system to evaluate the feasibility of this technology. In this system, 2000 dry metric ton per day woody biomass was assumed to be converted to bio-oil in hot compressed water and the bio-oil was hydrotreated and/or hydrocracked to produce gasoline and diesel range liquid fuel. Two cases were evaluated: a stage-of-technology (SOT) case based on the tests results, and a goal case considering potential improvements based on the SOT case. Process simulation models were developed and cost analysis was implemented based on the performance results. The major performance results included final products and co-products yields, raw materials consumption, carbon efficiency, and energy efficiency. The overall efficiency (higher heating value basis) was 52% for the SOT case and 66% for the goal case. The production cost, with a 10% internal rate of return and 2007 constant dollars, was estimated to be $1.29 /L for the SOT case and $0.74 /L for the goal case. The cost impacts of major improvements for moving from the SOT to the goal case were evaluated and the assumption of reducing the organics loss to the water phase lead to the biggest reduction in the production cost. Sensitivity analysis indicated that the final products yields had the largest impact on the production cost compared to other parameters. Plant size analysis demonstrated that the process was economically attractive if the woody biomass feed rate was over 1,500 dry tonne/day, the production cost was competitive with the then current petroleum-based gasoline price.

  7. Potential for Woody Bioenergy Crops Grown on Marginal Lands in the US Midwest to Reduce Carbon Emissions

    NASA Astrophysics Data System (ADS)

    Sahajpal, R.; Hurtt, G. C.; Fisk, J. P.; Izaurralde, R. C.; Zhang, X.

    2012-12-01

    While cellulosic biofuels are widely considered to be a low carbon energy source for the future, a comprehensive assessment of the environmental sustainability of existing and future biofuel systems is needed to assess their utility in meeting US energy and food needs without exacerbating environmental harm. To assess the carbon emission reduction potential of cellulosic biofuels, we need to identify lands that are initially not storing large quantities of carbon in soil and vegetation but are capable of producing abundant biomass with limited management inputs, and accurately model forest production rates and associated input requirements. Here we present modeled results for carbon emission reduction potential and cellulosic ethanol production of woody bioenergy crops replacing existing native prairie vegetation grown on marginal lands in the US Midwest. Marginal lands are selected based on soil properties describing use limitation, and are extracted from the SSURGO (Soil Survey Geographic) database. Yield estimates for existing native prairie vegetation on marginal lands modeled using the process-based field-scale model EPIC (Environmental Policy Integrated Climate) amount to ~ 6.7±2.0 Mg ha-1. To model woody bioenergy crops, the individual-based terrestrial ecosystem model ED (Ecosystem Demography) is initialized with the soil organic carbon stocks estimated at the end of the EPIC simulation. Four woody bioenergy crops: willow, southern pine, eucalyptus and poplar are parameterized in ED. Sensitivity analysis of model parameters and drivers is conducted to explore the range of carbon emission reduction possible with variation in woody bioenergy crop types, spatial and temporal resolution. We hypothesize that growing cellulosic crops on these marginal lands can provide significant water quality, biodiversity and GHG emissions mitigation benefits, without accruing additional carbon costs from the displacement of food and feed production.

  8. Effects of fire frequency and season on resprouting of woody plants in southeastern US pine-grassland communities.

    PubMed

    Robertson, Kevin M; Hmielowski, Tracy L

    2014-03-01

    Past studies suggest that rates of woody plant resprouting following a "topkilling" disturbance relate to timing of disturbance because of temporal patterns of below-ground carbohydrate storage. Accordingly, we hypothesized that fire-return interval (1 or 2 years) and season of burn (late dormant or early growing season) would influence the change in resprout growth rate from one fire-free interval to the next (Δ growth rate) for broadleaf woody plants in a pine-grassland in Georgia, USA. Resprout growth rate during one fire-free interval strongly predicted growth rate during the following fire-free interval, presumably reflecting root biomass. Length of fire-free interval did not have a significant effect on mean Δ growth rate. Plants burned in the late dormant season (February-March) had a greater positive Δ growth rate than those burned in the early growing season (April-June), consistent with the presumption that root carbohydrates are depleted and thus limiting during spring growth. Plants with resprout growth rates above a certain level had zero or negative Δ growth rates, indicating an equilibrium of maximum resprout size under a given fire-return interval. This equilibrium, as well as relatively reduced resprout growth rate following growing season fires, provide insight into how historic lightning-initiated fires in the early growing season limited woody plant dominance and maintained the herb-dominated structure of pine-grassland communities. Results also indicate tradeoffs between applying prescribed fire at 1- versus 2-year intervals and in the dormant versus growing seasons with the goal of limiting woody vegetation.

  9. A STELLA Model to Estimate Water and Nitrogen Dynamics in a Short-Rotation Woody Crop Plantation.

    PubMed

    Ouyang, Ying; Zhang, Jiaen; Leininger, Theodor D; Frey, Brent R

    2015-01-01

    Although short-rotation woody crop biomass production technology has demonstrated a promising potential to supply feedstocks for bioenergy production, the water and nutrient processes in the woody crop planation ecosystem are poorly understood. In this study, a computer model was developed to estimate the dynamics of water and nitrogen (N) species (e.g., NH-N, NO-N, particulate organic N, and soluble organic N [SON]) in a woody crop plantation using STELLA (tructural hinking and xperiential earning aboratory with nimation) software. A scenario was performed to estimate diurnal and monthly water and N variations of a 1-ha mature cottonwood plantation over a 1-yr simulation period. A typical monthly variation pattern was found for soil water evaporation, leaf water transpiration, and root water uptake, with an increase from winter to summer and a decrease from summer to the following winter. Simulations further revealed that the rate of soil water evaporation was one order of magnitude lower than that of leaf water transpiration. In most cases, the relative monthly water loss rates could be expressed as evapotranspiration > root uptake > percolation > runoff. Leaching of NO-N and SON depended not only on soil N content but also on rainfall rate and duration. Leaching of NO-N from the cottonwood plantation was about two times higher than that of SON. The relative monthly rate of N leaching was NO-N > SON > NH-N. This study suggests that the STELLA model developed is a useful tool for estimating water and N dynamics from a woody crop plantation.

  10. Technical Note: Linking climate change and downed woody debris decomposition across forests of the eastern United States

    USGS Publications Warehouse

    Russell, Matthew B.; Woodall, Christopher W.; D'Amato, Anthony W.; Fraver, Shawn; Bradford, John B.

    2014-01-01

    Forest ecosystems play a critical role in mitigating greenhouse gas emissions. Forest carbon (C) is stored through photosynthesis and released via decomposition and combustion. Relative to C fixation in biomass, much less is known about C depletion through decomposition of woody debris, particularly under a changing climate. It is assumed that the increased temperatures and longer growing seasons associated with projected climate change will increase the decomposition rates (i.e., more rapid C cycling) of downed woody debris (DWD); however, the magnitude of this increase has not been previously addressed. Using DWD measurements collected from a national forest inventory of the eastern United States, we show that the residence time of DWD may decrease (i.e., more rapid decomposition) by as much as 13% over the next 200 years, depending on various future climate change scenarios and forest types. Although existing dynamic global vegetation models account for the decomposition process, they typically do not include the effect of a changing climate on DWD decomposition rates. We expect that an increased understanding of decomposition rates, as presented in this current work, will be needed to adequately quantify the fate of woody detritus in future forests. Furthermore, we hope these results will lead to improved models that incorporate climate change scenarios for depicting future dead wood dynamics in addition to a traditional emphasis on live-tree demographics.

  11. Cavitation: a blessing in disguise? New method to establish vulnerability curves and assess hydraulic capacitance of woody tissues.

    PubMed

    Vergeynst, Lidewei L; Dierick, Manuel; Bogaerts, Jan A N; Cnudde, Veerle; Steppe, Kathy

    2015-04-01

    The hydraulic performance of woody species during drought is currently of high interest in the context of climate change. It is known that woody species have the capacity to mitigate water shortage by using internally stored water. Elastic shrinkage of living cells and also water release during cavitation contribute to the so-called 'hydraulic capacitance' (C) of the plant, which adds water to the transpiration stream and buffers fluctuations in water potential. Although sap-conducting conduits may ultimately serve as a water pool, cavitation will hamper the conduction of sap. Both hydraulic conductivity and C are thus inextricably linked and the interaction between both should be studied to better understand hydraulic functioning of woody species during drought. However, measurements of C are scarce and no distinction is usually made between C from elastic storage and C supplied by cavitation. In this paper, we propose a new method to assess both the decrease in hydraulic conductivity and the change in C during bench dehydration of a whole-branch segment using continuous measurements of acoustic emissions, radial diameter shrinkage and gravimetrical water loss. With this method we could establish proper vulnerability curves for grapevine (Vitis vinifera L. 'Johanniter') and quantify C during dehydration. Our results showed that loss in hydraulic conductivity during the cavitation phase was accompanied by 22-92% gain in hydraulic capacitance; therefore, a certain degree of cavitation may be tolerated in grapevine during periods of drought stress.

  12. Estimation of aboveground woody biomass using HJ-1 and Radarsat-2 data for deciduous forests in Daxing'anling, China

    NASA Astrophysics Data System (ADS)

    Liu, Qian; Yang, Le; Liu, Qinhuo; Li, Jing

    2014-11-01

    Accurate estimation of forest aboveground biomass is important for global carbon budgets and ecosystem change studies. Most algorithms for regional or global aboveground biomass estimation using optical and microwave remote sensing data are based on empirical regression and non-parametric training methods, which require large amount of ground measurements for training and are lacking of explicit interaction mechanisms between electromagnetic wave and vegetation. In this study, we proposed an optical/microwave synergy method based on a coherent polarimetric SAR model to estimate woody biomass. The study area is sparse deciduous forest dominated by birch with understory of shrubs and herbs in Daxing'anling, China. HJ-1, Radarsat-2 images, and field LAI were collected during May to August in 2013, tree biophysical parameters were measured at the field campaign during August to September in 2012. The effects of understory and wet ground were evaluated by introducing the NDVI derived from HJ-1 image and rain rate. Field measured LAI was used as an input to the SAR model to define the scattering and attenuation of the green canopy to the total backscatter. Finally, an logarithmic equation between the backscatter coefficient of direct forest scattering mechanism and woody biomass was generated (R2=0.582). The retrieval results were validated with the ground biomass measurements (RMSE=29.01ton/ha). The results indicated the synergy of optical and microwave remote sensing data based on SAR model has the potential to improve the accuracy of woody biomass estimation.

  13. Abundance of Woody Riparian Species in the Western USA in Relation to Phenology, Climate, and Flow Regime

    NASA Astrophysics Data System (ADS)

    Auble, G. T.; Friedman, J. M.; Scott, M. L.; Shafroth, P. B.; Merigliano, M. M.; Freehling, M. D.; Evans, R. E.; Griffin, E. R.

    2004-12-01

    We randomly selected 475 long-term U.S. Geological Survey stream gaging stations in 17 western states to relate the presence and abundance of woody species to environmental factors. Along a 1.3-km reach near each station we measured the cover of all species on a list of the 44 most abundant large woody riparian species in the region. We used logistic regression to fit the response of four abundant species to growing degree days and mean precipitation. Then we related relative abundance of these 4 species to timing of the flood peak in sites where the likelihood of occurrence was greater than 0.5. The exotics Tamarix ramosissima (saltcedar) and Elaeagnus angustifolia (Russian-olive) are now the third and fourth most frequently occurring large woody riparian species in the western U.S. and the second and fifth most abundant. In climatically suitable areas, species differences in reproductive phenology produce different relations of abundance to flow regime. Because of its limited period of seed release and viability in early summer, cottonwood (Populus deltoides) is disadvantaged where floods occur in the spring or fall. Abundances of saltcedar, because of its long period of seed release; Russian-olive, because of seed dormancy; and Salix exigua, because of the importance of vegetative spread, are much less sensitive to flood timing.

  14. Classification Based on Soil Heterogeneity: Tool for Land Management and Policy in a Woody Plant Encroached Region of Argentina

    NASA Astrophysics Data System (ADS)

    Svejcar, L.; Peinetti, R.; Bestelmeyer, B.

    2013-12-01

    Transitions from savanna to woody plant dominated, or in some cases thicketized, states have negative effects on ecosystem services worldwide. Attempts to restore historic savanna states have seen minimal success; woody plants continue to gain dominance and encroach into relict savannas. In the Caldenal Ecoregion of central Argentina, calden trees (Prosopis caldenia) and associated shrub species have established a pyrogenic dominance, thus outcompeting grass species. We quantitatively define states within the calden system using field collected plant and soils data that integrates woody and herbaceous strata, and looks for patterns of association between occurrence of states and inherent soil properties. We hypothesized that thicketized states would exhibit greater soil organic matter, total N, and total P compared to ancestral savanna states and that the level of calcium carbonate in the soil would influence plant composition. Thicketized states did not exhibit higher levels of soil organic matter, P, and N than savanna states and calcium carbonate in the soil did not directly impact vegetative composition. However, high silt-clay content soils showed the greatest vulnerability to thicketization. The information derived from this project can serve as a basis for distinguishing ecological sites based on predictions of thicketized state frequency and distribution and will assist land managers and policy makers in future land use decisions.

  15. Potential of woody plants from a Tonglushan ancient copper spoil heap for phytoremediation of heavy metal contaminated soil(1).

    PubMed

    Kang, Wei; Bao, Jianguo; Zheng, Jin; Xu, Fen; Wang, Liuming

    2016-03-25

    Fast-growing metal-accumulating woody plants are considered potential candidates for phytoremediation of metals. Tonglushan mining, one of the biggest Cu production bases in China, presents an important source of the pollution of environment. The sample was collected at Tonglushan ancient copper spoil heap. The aims were to measure the content of heavy metal in the soil and woody plants and to elucidate the phytoremediation potential of the plants. The result showed the soil Cu, Cd and Pb were the main contamination, the mean contents of which were 3166.73 mg/kg, 3.66 mg/kg and 137.06 mg/kg, respectively, belonged to severe contamination. 14 species from 14 genera of 13 families were collected and investigated, except for Ligutrums lucidum, the other 13 woody plants species were newly recorded in this area. In addition, to assess the ability of metal accumulation of these trees, we proposed enrichment index. Data suggested that Platanus × acerilolia, Broussonetia papyrifera, Ligutrums lucidum, Viburnum awabuk, Firminan simplex, Robina pseudoacacial, Melia azedarach and Osmanthus fragrans exhibited high accumulated capacity and strong tolerance to heavy metals. Therefore, Platanus × acerilolia and Broussonetia papyrifera can be planted in Pb contaminated areas; Viburnum awabuki, Firminan simplex, Robina pseudoacacial and Melia azedarach are the suitable trees for Cd contaminated areas; Viburnum awabuki, Melia azedarach, Ligutrums lucidum, Firminan simplex, Osmanthus fragrans and Robina pseudoacacial are appropriate to Cu, Pb and Cd multi-metal contaminated areas.

  16. Woody species diversity in forest plantations in a mountainous region of Beijing, China: effects of sampling scale and species selection.

    PubMed

    Zhang, Yuxin; Zhang, Shuang; Ma, Keming; Fu, Bojie; Anand, Madhur

    2014-01-01

    The role of forest plantations in biodiversity conservation has gained more attention in recent years. However, most work on evaluating the diversity of forest plantations focuses only on one spatial scale; thus, we examined the effects of sampling scale on diversity in forest plantations. We designed a hierarchical sampling strategy to collect data on woody species diversity in planted pine (Pinus tabuliformis Carr.), planted larch (Larix principis-rupprechtii Mayr.), and natural secondary deciduous broadleaf forests in a mountainous region of Beijing, China. Additive diversity partition analysis showed that, compared to natural forests, the planted pine forests had a different woody species diversity partitioning pattern at multi-scales (except the Simpson diversity in the regeneration layer), while the larch plantations did not show multi-scale diversity partitioning patterns that were obviously different from those in the natural secondary broadleaf forest. Compare to the natural secondary broadleaf forests, the effects of planted pine forests on woody species diversity are dependent on the sampling scale and layers selected for analysis. Diversity in the planted larch forest, however, was not significantly different from that in the natural forest for all diversity components at all sampling levels. Our work demonstrated that the species selected for afforestation and the sampling scales selected for data analysis alter the conclusions on the levels of diversity supported by plantations. We suggest that a wide range of scales should be considered in the evaluation of the role of forest plantations on biodiversity conservation.

  17. Isolation of high quality RNA from pistachio (Pistacia vera L.) and other woody plants high in secondary metabolites.

    PubMed

    Moazzam Jazi, Maryam; Rajaei, Saideh; Seyedi, Seyed Mahdi

    2015-10-01

    The quality and quantity of RNA are critical for successful downstream transcriptome-based studies such as microarrays and RNA sequencing (RNA-Seq). RNA isolation from woody plants, such as Pistacia vera, with very high amounts of polyphenols and polysaccharides is an enormous challenge. Here, we describe a highly efficient protocol that overcomes the limitations posed by poor quality and low yield of isolated RNA from pistachio and various recalcitrant woody plants. The key factors that resulted in a yield of 150 μg of high quality RNA per 200 mg of plant tissue include the elimination of phenol from the extraction buffer, raising the concentration of β-mercaptoethanol, long time incubation at 65 °C, and nucleic acid precipitation with optimized volume of NaCl and isopropyl alcohol. Also, the A260/A280 and A260/A230 of extracted RNA were about 1.9-2.1and 2.2-2.3, respectively, revealing the high purity. Since the isolated RNA passed highly stringent quality control standards for sensitive reactions, including RNA sequencing and real-time PCR, it can be considered as a reliable and cost-effective method for RNA extraction from woody plants.

  18. Predictive modelling of savannah woody cover: A multi-temporal and multi-sensor machine learning investigation

    NASA Astrophysics Data System (ADS)

    Higginbottom, Thomas; Symeonakis, Elias

    2016-04-01

    Effective monitoring of the Earth's ecosystems requires the availability of methods for quantifying the structural composition and cover of vegetation. This is especially important in heterogeneous environments, such as semi-arid savannahs which are naturally comprised of a dynamic mix of tree, shrub, and grass components. The fractional coverage of woody vegetation is a key ecosystem attribute in savannahs, particularly given current concerns over the invasion of grasslands by shrub species (shrub encroachment), or the over-exploitation of woody biomass for fuelwood. Remote sensing has a clear role to play in monitoring semi-arid environments, and in recent years the number of both spacebourne sensors and collected scenes has increased dramatically allowing for multi-temporal and multi-sensor investigations. Here we employ a statistical learning framework to assess the potential of optical and radar imagery for predicting fractional woody cover. We test a number of different model combinations in the Kruger National Park, South Africa. Our results show that combining Landsat and PALSAR data produces the most accurate predictions (R2 =0.65, P < 0.001, RMSE =0.094). However, this was only marginally more effective than a model using multitemporal Landsat data from the wet and dry seasons (R2 = 0.64 < 0.001,RMSE = 0.094). When a single temporal epoch is employed, dry season data consistently and significantly outperforms imagery from the wet period. These results are an important addition to the growing literature on fractional cover prediction.

  19. [Selection and purification potential evaluation of woody plant in vertical flow constructed wetlands in the subtropical area].

    PubMed

    Chen, Yong-Hua; Wu, Xiao-Fu; Hao, Jun; Chen, Ming-Li; Zhu, Guang-Yu

    2014-02-01

    In order to solve the problem that wetland herbaceous plants tend to die during winter in subtropics areas, selection and purification potential evaluation experiments were carried out by introducing into the constructed wetlands 16 species of woody wetland plants. Cluster analysis was performed by including the morphological characteristics, physiological characteristics, as well as nitrogen and phosphorus accumulation of the woody wetland plants. The results indicated that there were significant differences among the tested woody plants in their survival rate, height increase, root length increase and vigor, Chlorophyll content, Superoxide dismutase, Malonaldehyde, Proline, Peroxidase, biomass, average concentration and accumulation of nitrogen and phosphorus. Based on the established evaluation system, the tested plants were clustered into 3 groups. The plants in the 1st group possessing high purification potentials are Nerium oleander and Hibiscus syriacus. Those in the 2nd group possessing moderate purification potentials are Trachycarpus fortune, Llex latifolia Thunb., Gardenia jasminoides, Serissa foetida and Ilex crenatacv Convexa. And those in the 3rd group with low purification potentials are Jasminum udiflorum, Hedera helix, Ligustrum vicaryi, Ligustrum lucidum, Buxus sempervives, Murraya paniculata, Osmanthus fragrans, Mahoniafortune and Photinia serrulata.

  20. Woody invasions of urban trails and the changing face of urban forests in the great plains, USA

    USGS Publications Warehouse

    Nemec, K.T.; Allen, C.R.; Alai, A.; Clements, G.; Kessler, A.C.; Kinsell, T.; Major, A.; Stephen, B.J.

    2011-01-01

    Corridors such as roads and trails can facilitate invasions by non-native plant species. The open, disturbed habitat associated with corridors provides favorable growing conditions for many non-native plant species. Bike trails are a corridor system common to many urban areas that have not been studied for their potential role in plant invasions. We sampled five linear segments of urban forest along bike trails in Lincoln, Nebraska to assess the invasion of woody non-native species relative to corridors and to assess the composition of these urban forests. The most abundant plant species were generally native species, but five non-native species were also present: white mulberry (Morus alba), common buckthorn (Rhamnus cathartica), tree-of-heaven (Ailanthus altissima), honeysuckle (Lonicera spp.) and elm (Ulmus spp.). The distribution of two of the woody species sampled, common buckthorn and honeysuckle, significantly decreased with increasing distance from a source patch of vegetation (P = 0.031 and 0.030). These linear habitats are being invaded by non-native tree and shrub species, which may change the structure of these urban forest corridors. If non-native woody plant species become abundant in the future, they may homogenize the plant community and reduce native biodiversity in these areas. ?? 2011 American Midland Naturalist.

  1. Shoot desiccation and hydraulic failure in temperate woody angiosperms during an extreme summer drought.

    PubMed

    Nardini, Andrea; Battistuzzo, Marta; Savi, Tadeja

    2013-10-01

    Plant water status and hydraulics were measured in six woody angiosperms growing in a karstic woodland, during an extreme summer drought. Our aim was to take advantage of an unusual climatic event to identify key traits related to species-specific drought damage. The damage suffered by different species was assessed in terms of percentage of individuals showing extensive crown desiccation. Stem water potential (Ψstem ) and percent loss of hydraulic conductivity (PLC) were measured in healthy and desiccated individuals. Vulnerability to cavitation was assessed in terms of stem water potential inducing 50% PLC (Ψ50 ). Stem density (ρstem ) was also measured. Species-specific percentage of desiccated individuals was correlated to Ψ50 and ρstem . Crown desiccation was more widespread in species with less negative Ψ50 and lower ρstem . Desiccated individuals had lower Ψstem and higher PLC than healthy ones, suggesting that hydraulic failure was an important mechanism driving shoot dieback. Drought-vulnerable species showed lower safety margins (Ψstem  - Ψ50 ) than resistant ones. The Ψ50 , safety margins and ρstem values emerge as convenient traits to be used for tentative predictions of differential species-specific impact of extreme drought events on a local scale. The possibility that carbohydrate depletion was also involved in induction of desiccation symptoms is discussed.

  2. Large Woody Debris Characteristics of Maine Rivers: Its Frequency, Geometry, and Role In Sediment Storage

    NASA Astrophysics Data System (ADS)

    Magilligan, F. J.; Fisher, B.; Nislow, K.; Wright, J.; Mackey, G.

    2006-12-01

    Unlike watersheds in other parts of the US, little is known about the function of wood in New England Rivers, especially in Downeast Maine which possesses the few remaining wild runs of Atlantic Salmon in the US. Rivers in this region have been heavily affected by historical and contemporary land use disturbance especially hillslope and riparian logging which combine to limit the supply of large woody debris (LWD). Results from a multi-basin inventory representing over 40 river km of 6 drainages across Downeast Maine indicate LWD mean loadings of appx. 90 pieces per km with less than 1% having diameters> 50 cm with the rest split between 60 % small (10-20 cm) and 39% medium (20-50 cm) sizes. Because of their small size, most of this LWD is oriented parallel (~37%) or downstream (~33%), and channel-spanning stable wood pieces/jams are rare. Salmonid populations appear to depend on overwintering habitat and unlike other regions where LWD serves an important role in pool formation, LWD in Downeast Maine functions primarily as sites of critical sediment storage thus reducing overall channel embeddedness. To capture this function, we cored an array of LWD- related sediment wedges and used the fallout radionuclides, 7Be and 210Pb, to estimate sediment residence times. Results indicate that LWD is an important sediment sink having residence times ranging from the individual event to > several years.

  3. Influence of coarse woody debris on the soricid community in southeastern Coastal Plain pine stands.

    SciTech Connect

    Davis, Justin, C.; Castleberry, Steven, B.; Kilgo, John, C.

    2010-07-01

    Shrew abundance has been linked to the presence of coarse woody debris (CWD), especially downed logs, in many regions in the United States. We investigated the importance of CWD to shrew communities in managed upland pine stands in the southeastern United States Coastal Plain. Using a randomized complete block design, 1 of the following treatments was assigned to twelve 9.3-ha plots: removal (n 5 3; all downed CWD _10 cm in diameter and _60 cm long removed), downed (n 5 3; 5-fold increase in volume of downed CWD), snag (n 5 3; 10-fold increase in volume of standing dead CWD), and control (n 5 3; unmanipulated). Shrews (Blarina carolinensis, Sorex longirostris, and Cryptotis parva) were captured over 7 seasons from January 2007 to August 2008 using drift-fence pitfall trapping arrays within treatment plots. Topographic variables were measured and included as treatment covariates. More captures of B. carolinensis were made in the downed treatment compared to removal, and captures of S. longirostris were greater in downed and snag compared to removal. Captures of C. parva did not differ among treatments. Captures of S. longirostris were positively correlated with slope. Our results suggest that abundance of 2 of the 3 common shrew species of the southeastern Coastal Plain examined in our study is influenced by the presence of CWD.

  4. Ant-exclusion to promote biological control of soft scales (Hemiptera: Coccidae) on woody landscape plants.

    PubMed

    Vanek, Sarah J; Potter, Daniel A

    2010-12-01

    Ant-exclusion to facilitate biocontrol by endemic natural enemies was investigated for suppressing infestations of two coccids, calico scale, Eulecanium cerasorum (Cockerell), and magnolia scale, Neolecanium cornuparvum (Thro), in landscape settings. Application of sticky bands combined with basal trunk sprays resulted in 92-100% reduction in counts of honeydew-seeking ants, mainly Formica subsericea Say, ascending large, scale-infested sugar maple (Acer saccharum Marshall) trees. Ant-exclusion was associated with increased numbers of green lacewing, mainly Chrysoperla rufilabris (Burmeister), larvae and spiders on multiple sample dates, and 54 and 69% fewer surviving scale nymphs after the first and second growing seasons. Foliar sooty mold accumulation was also significantly reduced where ants were excluded. In feeding trials, C. rufilabris larvae collected from the tree canopies consumed large numbers of settled scale nymphs. On another site, ant-exclusion led to 82% reduction in magnolia scale densities on Magnolia stellata (Siebold & Zuccarini) Maximowicz, compared with controls, after 1 yr. Nine and 10 ant species were found tending calico and magnolia scales, respectively, at landscape sites in central Kentucky, and in situ observation trials showed that many of them aggressively attack approaching lacewing larvae. Our results suggest that where ants are closely associated with soft scales on woody landscape plants, ant-exclusion has potential as a sustainable pest management strategy.

  5. Species-level diversity of belowground structure in savanna woody plants

    NASA Astrophysics Data System (ADS)

    O'Donnell, F. C.; Caylor, K. K.; Bhattachan, A.; Dintwe, K.; D'Odorico, P.; Okin, G. S.

    2013-05-01

    Using compressed air, we excavated individual trees and shrubs and mapped their coarse root systems on a three-dimensional grid system up to 1.5 m depth. We excavated four woody savanna species at three sites spanning a climate gradient on the Kalahari Transect in southern Africa. Overall, species was more important than site in determining both large-scale and small-scale root system structure. The species excavated fell into two groups that coexisted across the climate gradient. Acacia mellifera and Terminalia sericea had straight roots in a laterally-extensive and relatively shallow system. Boscia albitrunca and Ochna pulchra had sinuous roots that were mostly concentrated beneath the canopy and were more prevalent in deep than near-surface soil layers, departing from the conventional model of decreasing root abundance with depth. The shallow-rooted species had small taproots, though it is unlikely that they reached the water table. Deep- and shallow-rootedness appear to correlate with other characteristics such as growth form (tree or shrub) and drought deciduousness. Acacia mellifera Boscia albitrunca

  6. Filtering the signature of submerged large woody debris from bathymetry data

    NASA Astrophysics Data System (ADS)

    White, Laurent; Hodges, Ben R.

    2005-07-01

    Modeling water velocities and depth for riverine aquatic habitat analysis requires fine-scale surveys of river bathymetry. The presence of submerged large woody debris (LWD) distorts the results of acoustic bathymetry surveys and subsequent modeling if the LWD data is not separated from the background river bathymetry. Submerged LWD typically appears in digital acoustic data for a low-gradient sand-bed river as impulse spikes of a few data points with a substantially shallower depth than the surrounding data. This paper examines the performance of linear and nonlinear filtering algorithms for removing impulse spikes from a digital bathymetry signal. A synthesized data set is used for control tests that quantify the error associated with each method. The more successful nonlinear filtering techniques (median and erosion filters) are used to filter single-beam echosounder data, from the Sulphur River in northeastern Texas, USA. Median filtering proved to be the best technique for removing LWD impulse spikes while leaving the background bathymetry relatively unchanged. Efficient automation of spike removal from a data set requires a method for selecting the filter characteristics without recourse to engineering judgment or prior experience. A method of a priori selecting the minimum filter order based upon the physical scales of the LWD and the statistics of the data separation in the survey is proposed based on scaling analysis, and validated with the study results.

  7. Allometry of within-fruit reproductive allocation in subtropical dicot woody species.

    PubMed

    Chen, Hong; Felker, Sara; Sun, Shucun

    2010-04-01

    Angiosperm fruits typically consist of pericarp and seed, which collectively function to maximize plant reproductive success. Within-fruit reproductive allocation has been scarcely examined across a wide range of fruit types and taxa although it is critical to the understanding of the evolution of fruit size and seed size. We investigated seed size, fruit size, seed number per fruit (SNF), and within-fruit biomass allocation between seed mass and pericarp mass for 62 dicot woody species (27 deciduous and 35 evergreen species) of a subtropical evergreen forest in southwest China. At the fruit level, total pericarp mass (TPM) isometrically scaled with increasing total seed mass (TSM) in the evergreen species and in the pooled data set, while TPM increased faster than TSM in the deciduous species. The slope difference is possibly due to the difference in the timing of fruit development between the two species groups. At the seed level, seed package (pericarp mass per seed) isometrically scaled with increasing seed size in the deciduous group, but less than isometrically in the evergreens and in the pooled data set. SNF was negatively correlated with seed size but positively correlated with the proportion of pericarp within fruits. In conclusion, within-fruit biomass allocation is significantly affected by seed size, fruit size, and SNF in both deciduous and evergreen species. The implications of the observed scaling relationships are discussed in relation to seed size evolution and global patterns of seed size variation.

  8. Water-use patterns of woody species in pineland and hammock communities of South Florida

    USGS Publications Warehouse

    Ewe, S.M.L.; da Silveira Lobo Sternberg, Leonel; Sternberg, L.; Busch, D.E.

    1999-01-01

    Rockland pine forests of south Florida dominated by Pinus elliottii var. densa characteristically have poor soil development in relation to neighboring hardwood hammocks. This has led to the hypothesis that Everglades hammock trees are more reliant on soil moisture derived from local precipitation whereas pineland plants must depend more on groundwater linked to broader regional hydrologic patterns. Because soil moisture sources are likely to vary more than groundwater sources, we hypothesized that hammock plants would exhibit correspondingly higher levels of dry season water stress. This was examined by measuring predawn water potentials, and by analyzing water uptake in representative hammock and pineland woody species using stable isotopes of plant water and that of potential sources during wet and dry seasons. Two species typical of each of the two communities were selected; a fifth species which was found in both communities, Lysiloma latisiliqua Benth., was also analyzed. Water content of soils in both communities decreased from wet to dry season. Consistent with our hypothesis, the change in predawn water potentials between the wet and dry season was less in pineland species than that of hammock species. Water potential changes in L. latisiliqua in both communities resembled that of hammock species more than pineland plants. Isotopic data showed that pineland species rely proportionately more on groundwater than hammock species. Nevertheless, unlike hammock species in the Florida Keys, mainland hammock species utilized a substantial amount of groundwater during the dry season.

  9. [Characteristics of coarse woody debris in Huzhong area of Great Xing' an Mountains].

    PubMed

    Wang, Wen-Juan; Chang, Yu; Liu, Zhi-Hua; Chen, Hong-Wei; Jing, Guo-Zhi; Zhang, Hong-Xin; Zhang, Chang-Meng

    2009-08-01

    An investigation was made on the coarse woody debris (CWD) in burned forestlands in Huzhong area of Great Xing' an Mountains. The loading capacity of CWD in the burned forestlands was 24.9-181.0 m3 x hm(-2), among which, snag and log occupied 24.3%-85.9% and 14.0%-75.7%, being 6.0-93.9 m3 x hm(-2) and 15.3-138.4 m3 x hm(-2), respectively. Significant differences were observed among burned forestlands and among years. The predominant DBH class of snag and log was 2.5-20 cm and 1.5-15 m, and the height of most snags and logs was 2.5-15 m and 5-20 cm, respectively. The loading capacity of CWD had no obvious change with the recovery of forest vegetation. The characteristics of CWD had a close relationship with pre-fire forest stand conditions and burn intensity.

  10. Fish populations associated with habitat-modified piers and natural woody debris in Piedmont Carolina reservoirs

    USGS Publications Warehouse

    Barwick, R.D.; Kwak, T.J.; Noble, R.L.; Barwick, D.H.

    2004-01-01

    A primary concern associated with reservoir shoreline residential development is reduction of littoral habitat complexity and diversity. One potential approach to compensate for this is the deployment of artificial-habitat modules under existing piers, but the benefit of this practice has not been demonstrated. To evaluate the effect of pier habitat modifications on fish populations in two Piedmont Carolina reservoirs, we studied 77 piers located on forty-seven, 100-m transects that were modified using plastic "fish hab" modules augmented with brush (brushed habs), hab modules alone (habs), or left unaltered for reference purposes. We sampled fish from all piers and transects during April, July, and October 2001 using a boat-mounted electrofisher. With few exceptions, catch rates were higher at brushed-hab piers and piers with habs than at reference piers during all seasons. Similarly, during spring and summer, fish abundance was generally higher on transects containing natural woody debris, brushed habs, and habs than on reference-developed transects; however, during fall, there were exceptions. Therefore, fish abundance associated with shorelines in these reservoirs appears to be related to the structural complexity of available habitat rather than structure composition. One year after installation, 92% of pier owners responding to a mail survey expressed satisfaction with pier modifications. Supplementing piers with habitat structures is recommended to enhance littoral habitat complexity for fishes in residentially developed reservoirs.

  11. Liquid phase fluorescence in situ RT-PCR analysis for gene expression analysis in woody stems.

    PubMed

    Gray-Mitsumune, M; Abe, H; Takahashi, J; Sundberg, B; Mellerowicz, E J

    2004-01-01

    We explore a rapid in situ RT-PCR protocol for gene expression studies in woody stem tissues. In situ RT-PCR was performed using fluorescent dye-conjugated nucleic acid and the fluorescence signals derived from target RNAs were detected using confocal laser scanning microscopy. The signal to background ratio was greatly enhanced by performing two rounds of PCR reactions, first without the fluorescent dye and second with the dye. Using this protocol, we obtained strong gene-specific signals in secondary stem tissues. The signals were PCR-dependent, as shown by the lack of cytoplasmic signals in the tissue sections in which either DNA polymerase or primers were omitted from PCR reactions, and were RNA-dependent, as shown by great reduction of cytoplasmic signals when sections were treated with RNase before RT reactions. To verify our protocol, transcript localization of the rbcS gene was examined in secondary stems of hybrid aspen ( Populus tremula L. x tremuloides Michx.) and compared to the chlorophyll autofluorescence signal. The in situ RT-PCR signals form the rbcS gene and chlorophyll autofluorescence co-localized in the same cell types. The signal was also confirmed by Northern blot analysis of isolated RNA from the cambium and developing xylem, thus confirming the validity of the protocol. Some difficulties of in situ transcript localization and the interpretation of the signal distribution in the secondary tissues are discussed.

  12. The drivers of woody species richness and density in a Neotropical savannah.

    PubMed

    Carvalho, Gustavo Henrique; Batalha, Marco Antônio

    2013-01-01

    Environmental filtering prevents species without certain attributes from occurring in local communities. Traits respond differently to different abiotic factors, assembling communities with varying composition along environmental gradients. Here, we measured proxies of soil fertility, disturbance by fire, response and physiological traits to assess how these variables interact to determine woody species richness and density in a Neotropical savannah. We explicitly incorporated our assumptions about how different abiotic filters influence different subsets of traits into a statistical model using structural equation modelling, yielding a more accurate representation of the assembly process. Fire had an effect on resistance traits, whereas soil fertility influenced physiological traits. Resistance traits explained both the richness and density of plots, whereas physiological traits explained only the density. Fewer fire events led to richer and denser plots. Similarly, areas with lower cation exchange capacity assembled less dense communities. Furthermore, we showed that structural equation modelling yielded a realistic representation of the bivariate interactions of distinct environmental filters with different subsets of traits.

  13. Somatic deleterious mutation rate in a woody plant: estimation from phenotypic data

    PubMed Central

    Bobiwash, K; Schultz, S T; Schoen, D J

    2013-01-01

    We conducted controlled crosses in populations of the long-lived clonal shrub, Vaccinium angustifolium (lowbush blueberry) to estimate inbreeding depression and mutation parameters associated with somatic deleterious mutation. Inbreeding depression level was high, with many plants failing to set fruit after self-pollination. We also compared fruit set from autogamous pollinations (pollen collected from within the same inflorescence) with fruit set from geitonogamous pollinations (pollen collected from the same plant but from inflorescences separated by several meters of branch growth). The difference between geitonogamous versus autogamous fitness within single plants is referred to as ‘autogamy depression' (AD). AD can be caused by somatic deleterious mutation. AD was significantly different from zero for fruit set. We developed a maximum-likelihood procedure to estimate somatic mutation parameters from AD, and applied it to geitonogamous and autogamous fruit set data from this experiment. We infer that, on average, approximately three sublethal, partially dominant somatic mutations exist within the crowns of the plants studied. We conclude that somatic mutation in this woody plant results in an overall genomic deleterious mutation rate that exceeds the rate measured to date for annual plants. Some implications of this result for evolutionary biology and agriculture are discussed. PMID:23778990

  14. Environmental enhancement using short-rotation woody crops and perennial grasses as alternative agricultural crops

    SciTech Connect

    Tolbert, V.R.; Schiller, A.

    1996-10-01

    Short-rotation woody crops and perennial grasses are grown as biomass feedstocks for energy and fiber. When replacing traditional row crops on similar lands, these alternative crops can provide multiple environmental benefits in addition to enhancing rural economies and providing valuable resources. The DOE is supporting research to address how these crops can provide environmental benefits to soil, water, and native wildlife species in addition to providing bioenergy feedstocks. Research is underway to address the potential for biomass crops to provide soils conservation and water quality improvements in crop settings. Replacement of traditional erosive row drops with biomass crops on marginal lands and establishment of biomass plantations as filter strips adjacent to streams and wetlands are being studied. The habitat value of different crops for wildlife species is also considered. Combining findings on wildlife use of individual plantations with information on the cumulative effects of multiple plantations on wildlife populations can provide guidance for establishing and managing biomass crops to enhance biodiversity while providing feedstocks. Data from site-specific environmental studies can provide input for evaluation of the effects of large-scale plantings at both landscape and regional levels of resolution.

  15. Environmental enhancement using short-rotation woody crops and perennial grasses as alternative agricultural crops

    SciTech Connect

    Tolbert, V.R.; Schiller, A.

    1995-12-31

    Short-rotation woody crops and perennial grasses are grown as biomass feedstocks for energy and fiber. When replacing traditional row crops on similar lands, these alternative crops can provide multiple environmental benefits in addition to enhancing rural economies and providing valuable feedstock resources. The Department of Energy is supporting research to address how these crops can provide environmental benefits to soil, water and native wildlife species in addition to providing bioenergy feedstocks. Research is underway to address the potential for biomass crops to provide soil conservation and water quality improvements in crop settings. Replacement of traditional erosive row crops with biomass crops on marginal lands and establishment of biomass plantations as filter strips adjacent to streams and wetlands are being studied. The habitat value of different biomass crops for selected wildlife species is also under study. To date, these studies have shown that in comparison with row crops biomass plantings of both grass and tree crops increased biodiversity of birds; however, the habitat value of tree plantations is not equivalent to natural forests. The effects on native wildlife of establishing multiple plantations across a landscape are being studied. Combining findings on wildlife use of individual plantations with information on the cumulative effects of multiple plantations on wildlife populations can provide guidance for establishing and managing biomass crops to enhance biodiversity while providing biomass feedstocks. Data from site-specific environmental studies can provide input for evaluation of the probable effects of large-scale plantings at both landscape and regional levels of resolution.

  16. Emission reductions from woody biomass waste for energy as an alternative to open burning.

    PubMed

    Springsteen, Bruce; Christofk, Tom; Eubanks, Steve; Mason, Tad; Clavin, Chris; Storey, Brett

    2011-01-01

    Woody biomass waste is generated throughout California from forest management, hazardous fuel reduction, and agricultural operations. Open pile burning in the vicinity of generation is frequently the only economic disposal option. A framework is developed to quantify air emissions reductions for projects that alternatively utilize biomass waste as fuel for energy production. A demonstration project was conducted involving the grinding and 97-km one-way transport of 6096 bone-dry metric tons (BDT) of mixed conifer forest slash in the Sierra Nevada foothills for use as fuel in a biomass power cogeneration facility. Compared with the traditional open pile burning method of disposal for the forest harvest slash, utilization of the slash for fuel reduced particulate matter (PM) emissions by 98% (6 kg PM/BDT biomass), nitrogen oxides (NOx) by 54% (1.6 kg NOx/BDT), nonmethane volatile organics (NMOCs) by 99% (4.7 kg NMOCs/BDT), carbon monoxide (CO) by 97% (58 kg CO/BDT), and carbon dioxide equivalents (CO2e) by 17% (0.38 t CO2e/BDT). Emission contributions from biomass processing and transport operations are negligible. CO2e benefits are dependent on the emission characteristics of the displaced marginal electricity supply. Monetization of emissions reductions will assist with fuel sourcing activities and the conduct of biomass energy projects.

  17. Genome-Wide Convergence during Evolution of Mangroves from Woody Plants.

    PubMed

    Xu, Shaohua; He, Ziwen; Guo, Zixiao; Zhang, Zhang; Wyckoff, Gerald J; Greenberg, Anthony; Wu, Chung-I; Shi, Suhua

    2017-04-01

    When living organisms independently invade a new environment, the evolution of similar phenotypic traits is often observed. An interesting but contentious issue is whether the underlying molecular biology also converges in the new habitat. Independent invasions of tropical intertidal zones by woody plants, collectively referred to as mangrove trees, represent some dramatic examples. The high salinity, hypoxia, and other stressors in the new habitat might have affected both genomic features and protein structures. Here, we developed a new method for detecting convergence at conservative Sites (CCS) and applied it to the genomic sequences of mangroves. In simulations, the CCS method drastically reduces random convergence at rapidly evolving sites as well as falsely inferred convergence caused by the misinferences of the ancestral character. In mangrove genomes, we estimated ∼400 genes that have experienced convergence over the background level of convergence in the nonmangrove relatives. The convergent genes are enriched in pathways related to stress response and embryo development, which could be important for mangroves' adaptation to the new habitat.

  18. Influence of Al-oxide on pesticide sorption to woody biochars with different surface areas.

    PubMed

    Shou, Jianxin; Dong, Huaping; Li, Jianfa; Zhong, Jiaxing; Li, Saijun; Lü, Jinhong; Li, Yimin

    2016-10-01

    Biochars' properties will change after application in soil due to the interactions with soil constituents, which would then impact the performance of biochars as soil amendment. For a better understanding on these interactions, two woody biochars of different surface areas (SA) were physically treated with aluminum oxide (Al-oxide) to investigate its potential influence on biochars' sorption property. Both the micropore area and mesopore (17∼500 Å in diameter) area of the low-SA biochar were enhanced by at least 1.5 times after treatment with Al-oxide, whereas the same treatment did not change the surface characteristics of the high-SA biochar due partly to its well-developed porosity. The enhanced sorption of the pesticide isoproturon to the Al-oxide-treated low-SA biochar was observed and is positively related to the increased mesopore area. The desorption hysteresis of pesticide from the low-SA biochar was strengthened because of more pesticide molecules entrapped in the expanded pores by Al-oxide. However, no obvious change of pesticide sorption to the high-SA biochar after Al-oxide treatment was observed, corresponding to its unchanged porosity. The results suggest that the influence of Al-oxide on the biochars' sorption property is dependent on their porosity. This study will provide valuable information on the use of biochars for reducing the bioavailability of pesticides.

  19. Disparate radiocesium leaching from two woody species by acceleration of litter decomposition using microbial inoculation.

    PubMed

    Hashida, Shin-Nosuke; Yoshihara, Toshihiro

    2016-10-01

    Studies focusing on the migration of radionuclides in the forest floor have demonstrated that the ecological half-life of radiocesium on organic layer containing the debris of plant litter with various fungi and microorganisms is shorter than that in the deeper soil zone, suggesting that the litter decomposition affects radiocesium mobilization. Here, we showed the involvement of lignin, one of the major cell wall components of plant litter, in the fate of contaminated radiocesium during the process of fungal litter decomposition. In this study, litter decomposition of two different woody species, broadleaf deciduous Japanese cherry consisted of hardwood lignin and coniferous evergreen Japanese cedar with softwood lignin, were accelerated by in vitro fungal inoculation. In vitro inoculation exhibited 1.93- to 2.59-times faster decomposition than field experiment. Then, the cherry litter lost approximately 25% of initially contaminated radiocesium within 1 month of in vitro decomposition, whereas the cedar litter kept initial level at least for 6 month. The retention of radiocesium correlated with thioglycolate lignin content in cedar litter but not in cherry litter. Consequently, the behavior of radiocesium contaminated in litter fall may vary depending on the contamination pathway or the manner of nutrient mobilization at the stage of abscission between evergreen and deciduous trees.

  20. Study on Woody Species Diversity in the Chestnut (Castanea sativa L.) Forests, Guilan, Iran

    NASA Astrophysics Data System (ADS)

    Poorbabaei, Hassan; Faghir, Marzia B.

    2008-01-01

    The purpose of this research was to study diversity of woody species in the Sweet chestnut (Castanea sativa L.) forests, Guilan, north of Iran. These forests are located in the Shafaroud and Emamzadeh Ebrahim regions. The Emamzadeh Ebrahim region is consisted of Visroud, Kishkhaleh, Askeh Koh, Male Lab, Doroudkhan, Galeroudkhan, Siahmazgy and Mali Anbar sites. Sampling was done in a selective manner in each site with a plot area of 50 m×50 m for tree and shrub layers and a circle 1000 m2 for tree saplings. In each plot, all trees ⩾10 cm in diameter at breast height (DBH) were identified and the DBH was measured, and shrub and tree sapling species were identified and recorded. In total, 68 sampling plots were taken using GPS device in the two regions. The results revealed that the mean richness, Simpson's index, Hill's N2, Shannon Wiener's function and N1 were higher in the Shafaroud region than other sites in tree, shrub and tree sapling layers. The highest and lowest mean values of evenness were obtained in the Kishkhaleh and Askekoh sites, respectively in tree layer, and similarly were in the Askekoh and Visroud in the shrub layer. The highest and lowest mean values of evenness were obtained in the Male Lab and Askeh Koh, respectively in the tree sapling layer.

  1. The effect of temperature on the rate of cyanide metabolism of two woody plants.

    PubMed

    Yu, Xiaozhang; Trapp, Stefan; Zhou, Puhua; Hu, Hao

    2005-05-01

    The response of cyanide metabolism rates of two woody plants to changes in temperature is investigated. Detached leaves (1.0 g fresh weight) from weeping willow (Salix babylonica L.) and Chinese elder (Sambucus chinensis Lindl.) were kept in glass vessels with 100ml of aqueous solution spiked with potassium cyanide for a maximum of 28 h. Ten different temperatures were used ranging from 11 degrees C to 32 degrees C. The disappearance of aqueous cyanide was analyzed spectrophotometrically. The cyanide removal rate of Chinese elder was higher than that of weeping willow at all temperatures. The highest cyanide removal rate for Chinese elder was found at 30 degrees C with a value of 12.6 mg CN kg(-1) h(-1), whereas the highest value of the weeping willow was 9.72 mg CN kg(-1) h(-1) at 32 degrees C. The temperature coefficient values, Q10, which are the ratio of removal rates at a 10 degree difference, were determined for Chinese elder and weeping willow to 1.84 and 2.09, respectively, indicating that the cyanide removal rate of weeping willow was much more susceptible to changes in temperature than that of the Chinese elder. In conclusion, changes in temperature have a substantial influence on the removal rate of cyanide by plants.

  2. Valuation of ecosystem services of commercial shrub willow (Salix spp.) woody biomass crops.

    PubMed

    Bressler, Alison; Vidon, Philippe; Hirsch, Paul; Volk, Timothy

    2017-04-01

    The development of shrub willow as a bioenergy feedstock contributes to renewable energy portfolios in many countries with temperate climates and marginal croplands due to excessive moisture. However, to fully understand the potential of shrub willow as an alternative crop on marginal cropland, more research is needed to understand the potential of shrub willow for providing a variety of ecosystem services. At the same time, there is much need for research developing strategies to value ecosystem services beyond conventional valuation systems (e.g., monetary, intrinsic). In this context, this project investigates the ecosystem services of shrub willow woody biomass from an environmental science perspective, and proposes a new avenue to assess ecosystem services for management purposes based on the relative value of key ecosystem services under various land management strategies (i.e., willow vs. corn vs. hay). On marginal cropland in the US Northeast, shrub willow may be used to replace crops like corn or hay. Transitioning from conventional corn or hay to willow tends to reduce nutrient loss and erosion, improve biodiversity and adaptability to climate change, and increase access to recreational activities. However, it is unlikely to change soil carbon pools or greenhouse gas emissions at the soil-atmosphere interface. By encouraging decision makers to weigh the pros and cons of each management decision (i.e., willow vs. corn vs. hay) based on the situation, the ecosystems services valuation method used here provides a clear framework for decision making in a watershed management context.

  3. Changes in woody debris and bed material texture in a gravel-bed channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, Judith K.; Rice, Stephen P.

    2004-06-01

    This study investigated the response of bed material texture under two distinct periods of log jam conditions in a 900-m study reach of Carnation Creek, Vancouver Island, BC. A field program extending over seven flood seasons, coupled with existing streamflow records, channel maps, and low-altitude aerial photography, provides observations of jam stability and permeability, surface and subsurface grain-size, as well as bed material fluxes, sediment supply calibre, streambed stability, and sediment exchange near jams. All jams functioned as partial dams throughout the field program, but the overall perturbation of sediment transfers decreased when two jams were breached. Bed material texture exhibited the largest differences over the study reach during a period when log jams exerted a stronger influence over the passage of water and sediment. At individual gravel bars, most adjustments in surface and subsurface grain-size constituted less than a 20% change in percentile values. Larger changes occurred primarily in subsurface sediment. Temporal patterns in bed material texture exhibited variation between bars, but downstream of breached jams, surface sediment conformed to the expected fining trend, while the subsurface sediment increased in size. Surface and subsurface sediments evolved in the same direction only 64% of the time, and the different magnitudes of adjustment caused local armor ratios to vary over time. Results highlight that the temporal dynamism of large woody debris (LWD) should be coupled with spatial considerations for effective stream restoration and management of streambed sediment.

  4. Cultural treatment of selected species for woody biomass production in the Pacific northwest. Annual report

    SciTech Connect

    Not Available

    1980-02-01

    Progress was made toward establishing two sites to study the effect of cultural treatment on two selected species, black cottonwood and red alder, for woody biomass production. The first study area (the dry site), located on the City of Seattle's Cedar River Watershed, at North Bend, Washington, was established and put into production during late winter 1978 and spring of 1979. Cottonwood cuttings obtained from US Forest Service land near Skykomish, Washington, were cut into 18 to 20 inch lengths and outplanted in March and April. Alder was obtained from logging roads near the plantation site as wildlings and transplanted immediately after pulling. Both species were planted in pure plots, mixes of 1:1, and mixes of 2:1 with spacings of 2x4, 4x6 and 6x8 feet. Row cultivation was performed three times during the growing season. Fertilizer and irrigation were not applied due to logistical problems. Survival for both species exceeded 98%. Growth was moderate to poor because of an extremely dry summer. The second area (the wet site) is being established on the University of Washington's Lee Experimental Forest north of Woodinville, Washington. The area was clearcut logged in September and October of 1979. Stumps were removed shortly thereafter.

  5. Improvement of acetone, butanol, and ethanol production from woody biomass using organosolv pretreatment.

    PubMed

    Amiri, Hamid; Karimi, Keikhosro

    2015-10-01

    A suitable pretreatment is a prerequisite of efficient acetone-butanol-ethanol (ABE) production from wood by Clostridia. In this study, organosolv fractionation, an effective pretreatment with ability to separate lignin as a co-product, was evaluated for ABE production from softwood pine and hardwood elm. ABE production from untreated woods was limited to the yield of 81 g ABE/kg wood and concentration of 5.5 g ABE/L. Thus, the woods were pretreated with aqueous ethanol at elevated temperatures before hydrolysis and fermentation to ABE by Clostridium acetobutylicum. Hydrolysis of pine and elm pretreated at 180 °C for 60 min resulted in the highest sugar concentrations of 16.8 and 23.2 g/L, respectively. The hydrolysate obtained from elm was fermented to ABE with the highest yield of 121.1 g/kg and concentration of 11.6 g/L. The maximum yield of 87.9 g/kg was obtained from pine pretreated for 30 min at 150 °C. Moreover, structural modifications in the woods were investigated and related to the improvements. The woody biomasses are suitable feedstocks for ABE production after the organosolv pretreatment. Effects of the pretreatment conditions on ABE production might be related to the reduced cellulose crystallinity, reduced lignin and hemicellulose content, and lower total phenolic compounds in the hydrolysates.

  6. Investigation of Prediction Method and Fundamental Thermo-decomposition Properties on Gasification of Woody Biomass

    NASA Astrophysics Data System (ADS)

    Morita, Akihiro

    Recently, development of energy transfer technology based on woody biomass remarkably has been forwarding accompanied biomass boom for gasification and liquefaction. To elevate on yield of energy into biomass for transportation and exergy is extremely important for essential utilization and production of bio-fuels. Because, conversion to bio-fuel must be discussion in detail thermo-decomposition characteristics for biomass main composition formed on cellulose and hemicelluloses, lignin. In this research, we analyze thermo-decomposition characteristics of each biomass main composition on both active (air) and passive (N2) atmosphere. Especially, we suggest predict model of gasification based on change of atomic carbon ratio with thermo-decomposition. 1) Even if it heat-treats cedar chip by 473K, loss of energy hardly produces it. From this, it acquired that the substance contributed to weight reduction was a low ingredient of energy value. 2) If cedar chip is heated in the 473K around, it can be predicted that the substance with a low energy value like water or acetic acid has arisen by thermal decomposition. It suggested that the transportation performance of the biomass improved by choosing and eliminating these. 3) Each ingredient of hydrogen, nitrogen, and oxygen which dissipated in the gasification process acquired that it was direct proportion to the carbonaceous dissipation rate. 4) The action at the time of thermo-decomposition of (the carbon, hydrogen, nitrogen, oxygen which are) the main constituent factors of the biomass suggested a possibility of being predicted by a statistical method.

  7. Resistance to Acarapis woodi by honey bees (Hymenoptera: Apidae): divergent selection and evaluation of selection progress.

    PubMed

    Nasr, M E; Otis, G W; Scott-Dupree, C D

    2001-04-01

    Two generations of honey bees, Apis mellifera L., selected for resistance to tracheal mites, Acarapis woodi (Rennie), were produced from a foundation stock. The mite resistant lines had significantly low mite abundances and prevalences in each selected generation. The high mite-resistant lines of the first selected generation showed resistance equal to that of bees that had undergone natural selection from tracheal mite infestations for 3 yr in New York. Additionally, the high mite-resistant lines of the second selected generation and Buckfast bees had significantly lower mite abundances and prevalences than honey bees from control colonies which had never been exposed to tracheal mite infestation in Ontario. These results corroborate studies that have shown that honey bees possess genetic components for tracheal mite resistance that can be readily enhanced in a breeding program. The two methods used for evaluating relative resistance of honey bees to tracheal mites, a short-term bioassay and evaluation in field colonies, were positively correlated (rs = 0.64, P < 0.001).

  8. Respiration from coarse woody debris as affected by moisture and saprotroph functional diversity in Western Oregon.

    PubMed

    Progar, R A; Schowalter, T D; Freitag, C M; Morrell, J J

    2000-08-01

    Decomposing coarse woody debris (CWD) is a conspicuous and important component of forest ecosystems. Seasonal temperature and precipitation patterns influence heterotroph activity, which determines the rate of CWD decomposition. We tested the hypothesis that moisture content and heterotroph community composition influence carbon flux in freshly-cut Douglas fir (Pseudotsuga menziesii) logs. To evaluate the effects of physical penetration of bark and wood and transmission of basidiomycete compared with ascomycete fungi by insects, 360 experimental logs were assigned to five replicate sites, each with 12 heterotroph×moisture treatment combinations in 1995. Half of the logs in each heterotroph treatment received normal rainfall and half were placed individually under elevated clear plastic tents to reduce water inputs. Respiration was measured every 1-3 months. In 1996 and 1997 a different log representing each treatment combination was harvested from each replicate and analyzed for the presence of inoculated and colonizing fungi. Logs inoculated with decay fungi had higher respiration than uninoculated logs but this effect only approached significance (P=0.08) during the first season. Respiration was significantly higher in sheltered than in exposed logs. Our results indicate that respiration and wood decomposition rates may be depressed by high moisture content in the wet forests of the coastal Pacific Northwest.

  9. Essential Role of Caffeoyl Coenzyme A O-Methyltransferase in Lignin Biosynthesis in Woody Poplar Plants

    PubMed Central

    Zhong, Ruiqin; Morrison, W. Herbert; Himmelsbach, David S.; Poole, Farris L.; Ye, Zheng-Hua

    2000-01-01

    Caffeoyl coenzyme A O-methyltransferase (CCoAOMT) has recently been shown to participate in lignin biosynthesis in herbacious tobacco plants. Here, we demonstrate that CCoAOMT is essential in lignin biosynthesis in woody poplar (Populus tremula × Populus alba) plants. In poplar stems, CCoAOMT was found to be expressed in all lignifying cells including vessel elements and fibers as well as in xylem ray parenchyma cells. Repression of CCoAOMT expression by the antisense approach in transgenic poplar plants caused a significant decrease in total lignin content as detected by both Klason lignin assay and Fourier-transform infrared spectroscopy. The reduction in lignin content was the result of a decrease in both guaiacyl and syringyl lignins as determined by in-source pyrolysis mass spectrometry. Fourier-transform infrared spectroscopy indicated that the reduction in lignin content resulted in a less condensed and less cross-linked lignin structure in wood. Repression of CCoAOMT expression also led to coloration of wood and an elevation of wall-bound p-hydroxybenzoic acid. Taken together, these results indicate that CCoAOMT plays a dominant role in the methylation of the 3-hydroxyl group of caffeoyl CoA, and the CCoAOMT-mediated methylation reaction is essential to channel substrates for 5-methoxylation of hydroxycinnamates. They also suggest that antisense repression of CCoAOMT is an efficient means for genetic engineering of trees with low lignin content. PMID:11027707

  10. Advances in Modeling Streambank Stability by Incorporating the Mechanical and Hydrologic Effects of Woody and Herbaceous Riparian Vegetation

    NASA Astrophysics Data System (ADS)

    Simon, A.; Collison, A. J.

    2001-12-01

    Sediment is one of the principle pollutants of surface waters of the United States. Sediment derived from streambanks by mass failure is a significant contributor to water-quality and land management problems. Accurately modeling streambank stability and potential mitigation strategies using riparian vegetation involves quantifying the hydrologic and mechanical factors that control the driving and resisting forces imposed by bank material, ground and surface water and the vegetation. Stabilization of streambanks using riparian vegetation offers numerous potential benefits and some potential problems that are related to mechanical and hydrological effects that are rarely quantified. In this study mechanical reinforcement of various woody and herbaceous riparian species is quantified with in situ, field measurements of root tensile strength, root sizes and root distribution that are used to calculate increases in soil cohesion. Hydrological effects of vegetation are monitored at the Goodwin Creek Experimental Watershed, Mississippi using interception plots and tensiometers under three vegetative covers: cropped grass `control' cover, clumps of eastern gamma grass, and a deciduous woody-vegetation stand. The ARS Bank-Stability Model which accounts for complex bank geometries, up to five soil layers, positive and negative pore-water pressures and confining pressure due to streamflow is used to evaluate the effectiveness of various vegetative treatments based on the field data. The model is used to evaluate the individual and combined effects of vegetation on streambank stability. On April 4 th 2000 prolonged rainfall at the field site caused bank failure at the control cover plot, providing useful validation data for the analysis. The resulting factor of safety (Fs) values (incorporating both hydrological and mechanical effects) were 1.04, 1.64 and 2.18, respectively. Results show that the main contribution of the woody-vegetation to bank stability during the study

  11. Mapping the spatial and temporal distributions of woody debris in streams of the Greater Yellowstone Ecosystem, USA

    NASA Astrophysics Data System (ADS)

    Marcus, W. Andrew; Marston, Richard A.; Colvard, Charles R.; Gray, Robin D.

    2002-05-01

    The objectives of this study were: (1) to document spatial and temporal distributions of large woody debris (LWD) at watershed scales and investigate some of the controlling processes; and (2) to judge the potential for mapping LWD accumulations with airborne multispectral imagery. Field surveys were conducted on the Snake River, Soda Butte Creek, and Cache Creek in the Greater Yellowstone Ecosystem, USA. The amount of woody debris per kilometer is highest in 2nd order streams, widely variable in 3rd and 4th order streams, and relatively low in the 6th order system. Floods led to increases in woody debris in 2nd order streams. Floods redistributed the wood in 3rd and 4th order streams, removing it from the channel and stranding it on bars, but appeared to generate little change in the total amount of wood throughout the channel system. The movement of woody debris suggests a system that is the reverse of most sediment transport systems in mountains. In 1st and 2nd order tributaries, the wood is too large to be moved and the system is transport-limited, with floods introducing new material through undercutting, but not removing wood through downstream transport. In the intermediate 3rd and 4th order channels, the system displays characteristics of dynamic equilibrium, where the channel is able remove the debris at approximately the same rate that it is introduced. The spatial distribution and quantity of wood in 3rd and 4th order reaches varies widely, however, as wood is alternatively stranded on gravel bars or moved downstream during periods of bar mobilization. In the 6th order and larger channels, the system becomes supply-limited, where almost all material in the main stream can be transported out of the central channel by normal stream flows and deposition occurs primarily on banks or in eddy pool environments. Attempts to map woody debris with 1-m resolution digital four-band imagery were generally unsuccessful, primarily because the imagery could not

  12. Quantitative woody cover reconstructions from eastern continental Asia of the last 22 kyr reveal strong regional peculiarities

    NASA Astrophysics Data System (ADS)

    Tian, Fang; Cao, Xianyong; Dallmeyer, Anne; Ni, Jian; Zhao, Yan; Wang, Yongbo; Herzschuh, Ulrike

    2016-04-01

    We present a calibration-set based on modern pollen and satellite-based Advanced Very High Resolution Radiometer (AVHRR) observations of woody cover (including needleleaved, broadleaved and total tree cover) in eastern continental Asia, which shows good performance under cross-validation with the modern analogue technique (all the coefficients of determination between observed and predicted values are greater than 0.65). The calibration-set is used to reconstruct woody cover from a taxonomically harmonized and temporally standardized fossil pollen dataset (including 274 cores) with 500-year resolution over the last 22 kyr. The spatial range of forest has not noticeably changed in eastern continental Asia during the last 22 kyr, although woody cover has, especially at the margin of the eastern Tibetan Plateau and in the forest-steppe transition area of north-central China. Vegetation was sparse during the LGM in the present forested regions, but woody cover increased markedly at the beginning of the Bølling/Allerød period (B/A; ca. 14.5 ka BP) and again at the beginning of the Holocene (ca. 11.5 ka BP), and is related to the enhanced strength of the East Asian Summer Monsoon. Forest flourished in the mid-Holocene (ca. 8 ka BP) possibly due to favourable climatic conditions. In contrast, cover was stable in southern China (high cover) and arid central Asia (very low cover) throughout the investigated period. Forest cover increased in the north-eastern part of China during the Holocene. Comparisons of these regional pollen-based results with simulated forest cover from runs of a global climate model (for 9, 6 and 0 ka BP (ECHAM5/JSBACH ∼1.125° spatial resolution)) reveal many similarities in temporal change. The Holocene woody cover history of eastern continental Asia is different from that of other regions, likely controlled by different climatic variables, i.e. moisture in eastern continental Asia; temperature in northern Eurasia and North America.

  13. Rapid and effective oxidative pretreatment of woody biomass at mild reaction conditions and low oxidant loadings

    PubMed Central

    2013-01-01

    Background One route for producing cellulosic biofuels is by the fermentation of lignocellulose-derived sugars generated from a pretreatment that can be effectively coupled with an enzymatic hydrolysis of the plant cell wall. While woody biomass exhibits a number of positive agronomic and logistical attributes, these feedstocks are significantly more recalcitrant to chemical pretreatments than herbaceous feedstocks, requiring higher chemical and energy inputs to achieve high sugar yields from enzymatic hydrolysis. We previously discovered that alkaline hydrogen peroxide (AHP) pretreatment catalyzed by copper(II) 2,2΄-bipyridine complexes significantly improves subsequent enzymatic glucose and xylose release from hybrid poplar heartwood and sapwood relative to uncatalyzed AHP pretreatment at modest reaction conditions (room temperature and atmospheric pressure). In the present work, the reaction conditions for this catalyzed AHP pretreatment were investigated in more detail with the aim of better characterizing the relationship between pretreatment conditions and subsequent enzymatic sugar release. Results We found that for a wide range of pretreatment conditions, the catalyzed pretreatment resulted in significantly higher glucose and xylose enzymatic hydrolysis yields (as high as 80% for both glucose and xylose) relative to uncatalyzed pretreatment (up to 40% for glucose and 50% for xylose). We identified that the extent of improvement in glucan and xylan yield using this catalyzed pretreatment approach was a function of pretreatment conditions that included H2O2 loading on biomass, catalyst concentration, solids concentration, and pretreatment duration. Based on these results, several important improvements in pretreatment and hydrolysis conditions were identified that may have a positive economic impact for a process employing a catalyzed oxidative pretreatment. These improvements include identifying that: (1) substantially lower H2O2 loadings can be used that

  14. Abundance and Morphological Effects of Large Woody Debris in Forested Basins of Southern Andes

    NASA Astrophysics Data System (ADS)

    Andreoli, A.; Comiti, F.; Lenzi, M. A.

    2006-12-01

    The Southern Andes mountain range represents an ideal location for studying large woody debris (LWD) in streams draining forested basins thanks to the presence of both pristine and managed woodland, and to the general low level of human alteration of stream corridors. However, no published investigations have been performed so far in such a large region. The investigated sites of this research are three basins (9-13 km2 drainage area, third-order channels) covered by Nothofagus forests: two of them are located in the Southern Chilean Andes (the Tres Arroyos in the Malalcahuello National Reserve and the Rio Toro within the Malleco Natural Reserve) and one basin lies in the Argentinean Tierra del Fuego (the Buena Esperanza basin, near the city of Ushuaia). Measured LWD were all wood pieces larger than 10 cm in diameter and 1 m in length, both in the active channel and in the adjacent active floodplain. Pieces forming log jams were all measured and the geometrical dimensions of jams were taken. Jam type was defined based on Abbe and Montgomery (2003) classification. Sediment stored behind log-steps and valley jams was evaluated approximating the sediment accumulated to a solid wedge whose geometrical dimensions were measured. Additional information relative to each LWD piece were recorded during the field survey: type (log, rootwad, log with rootwads attached), orientation to flow, origin (floated, bank erosion, landslide, natural mortality, harvest residuals) and position (log-step, in-channel, channel-bridging, channel margins, bankfull edge). In the Tres Arroyos, the average LWD volume stored within the bankfull channel is 710 m3 ha-1. The average number of pieces is 1,004 per hectare of bankfull channel area. Log-steps represent about 22% of all steps, whereas the elevation loss due to LWD (log-steps and valley jams) results in 27% loss of the total stream potential energy. About 1,600 m3 of sediment (assuming a porosity of 20%) is stored in the main channel

  15. The geomorphic function and characteristics of large woody debris in low gradient rivers, coastal Maine, USA

    NASA Astrophysics Data System (ADS)

    Magilligan, F. J.; Nislow, K. H.; Fisher, G. B.; Wright, J.; Mackey, G.; Laser, M.

    2008-05-01

    The role, function, and importance of large woody debris (LWD) in rivers depend strongly on environmental context and land use history. The coastal watersheds of central and northern Maine, northeastern U.S., are characterized by low gradients, moderate topography, and minimal influence of mass wasting processes, along with a history of intensive commercial timber harvest. In spite of the ecological importance of these rivers, which contain the last wild populations of Atlantic salmon ( Salmo salar) in the U.S., we know little about LWD distribution, dynamics, and function in these systems. We conducted a cross-basin analysis in seven coastal Maine watersheds, documenting the size, frequency, volume, position, and orientation of LWD, as well as the association between LWD, pool formation, and sediment storage. In conjunction with these LWD surveys, we conducted extensive riparian vegetation surveys. We observed very low LWD frequencies and volumes across the 60 km of rivers surveyed. Frequency of LWD ≥ 20 cm diameter ranged from 15-50 pieces km - 1 and wood volumes were commonly < 10-20 m 3 km - 1 . Moreover, most of this wood was located in the immediate low-flow channel zone, was oriented parallel to flow, and failed to span the stream channel. As a result, pool formation associated with LWD is generally lacking and < 20% of the wood was associated with sediment storage. Low LWD volumes are consistent with the relatively young riparian stands we observed, with the large majority of trees < 20 cm DBH. These results strongly reflect the legacy of intensive timber harvest and land clearing and suggest that the frequency and distribution of LWD may be considerably less than presettlement and/or future desired conditions.

  16. Invasive Buddleja davidii allocates more nitrogen to its photosynthetic machinery than five native woody species.

    PubMed

    Feng, Yu-Long; Auge, Harald; Ebeling, Susan K

    2007-09-01

    The general-purpose genotype hypothesis and the hypothesis of the evolution of invasiveness predict that invasive species are characterized by particular traits that confer invasiveness. However, these traits are still not well-defined. In this study, ecophysiological traits of eight populations of the invasive shrub Buddleja davidii from a wide range of European locations and five co-occurring native woody species in Germany were compared in a common garden experiment. We hypothesized that the invader has higher resource capture ability and utilization efficiency than the natives. No differences were detected among the eight populations of B. davidii in any of the traits evaluated, indicating that the invader did not evolve during range expansion, thus providing support to the general-purpose genotype hypothesis. The invader showed significantly higher maximum electron transport rate, maximum carboxylation rate, carboxylation efficiency, light-saturated photosynthetic rate (P(max)) and photosynthetic nitrogen utilization efficiency (PNUE) than the five natives. Leaf nitrogen content was not significantly different between the invader and the natives, but the invader allocated more nitrogen to the photosynthetic machinery than the natives. The increased nitrogen content in the photosynthetic machinery resulted in a higher resource capture ability and utilization efficiency in the invader. At the same intercellular CO(2) concentration, P (max) was significantly higher in the invader than in the natives, again confirming the importance of the higher nitrogen allocation to photosynthesis. The invader reduced metabolic cost by increasing the ratio of P (max) to dark respiration rate (R (d)), but it did not reduce carbon cost by increasing the specific leaf area and decreasing leaf construction cost. The higher nitrogen allocation to the photosynthetic machinery, P(max), PNUE and P(max)/R(d) may facilitate B. davidii invasion, although studies involving a wide range of

  17. Short-term dynamics of evaporative enrichment of xylem water in woody stems: implications for ecohydrology.

    PubMed

    Martín-Gómez, Paula; Serrano, Luis; Ferrio, Juan Pedro

    2016-12-14

    In ecohydrology, it is generally assumed that xylem water reflects the water source used by plants. Several studies have reported isotopic enrichment within woody tissues, particularly during dormancy periods or after long periods of inactivity. However, little is known about the short-term dynamics of this process. Here we assessed the magnitude and dynamics of xylem isotopic enrichment in suberized twigs of pines and oaks. We performed a series of laboratory experiments, in which we monitored hourly changes in water content and isotopic composition under two contrasting scenarios of sap flow restriction. First, we simulated the effect of extreme hydraulic failure by excising twigs to restrict sap flow, while sealing the wounds to ensure that water loss took place only through the leaves or bark, as would be the case for evaporation in attached stems. Second, we studied the effect of reduced leaf transpiration by darkening with aluminium foil all the leaves of healthy, well-watered saplings growing in pot conditions. We found evidence of fast evaporative enrichment in metabolically active stems, as a consequence of a temporal decline in sap flow rates, and not necessarily linked to a traceable decline in stem water content. The excision experiments showed significant isotopic changes (~+1‰ in oxygen) appearing in <1 h. Similarly, the pot experiment showed a progressive increase in isotope composition (up to +8‰ in oxygen in a 3-day cycle) when the leaves were covered, and a rapid recovery to initial values when sap flow rates were re-established. We conclude that evaporative enrichment of xylem water in stems is a highly dynamic process that may have significant effects even during short periods of restricted water flow. This has important implications for the study of plant water uptake, as well as for ecosystem- and global-scale hydrological models.

  18. Invasive rats alter woody seedling composition on seabird-dominated islands in New Zealand.

    PubMed

    Grant-Hoffman, Madeline N; Mulder, Christa P; Bellingham, Peter J

    2010-06-01

    Invasive rats (Rattus rattus, R. norvegicus, R. exulans) have large impacts on island habitats through both direct and indirect effects on plants. Rats affect vegetation by extirpating burrowing seabirds through consumption of eggs, chicks, and adults. These seabirds serve as ecosystem engineers, affecting plant communities by burying and trampling seeds and seedlings, and by altering microclimate. Rats also directly affect plant communities by consuming seeds and seedlings. We studied the direct and indirect impacts of rats on the seedlings of woody plants on 21 islands in northern New Zealand. We compared seedling densities and richness on islands which differed in status with respect to rats: nine islands where rats never invaded, seven islands where rats were present at the time of our study, and five islands where rats were either eradicated or where populations were likely to be small as a result of repeated eradications and re-invasions. In addition, we compared plots from a subset of the 21 islands with different burrow densities to examine the effects of burrowing seabirds on plants while controlling for other factors that differ between islands. We categorized plant communities by species composition and seedling density in a cluster analysis. We found that burrow densities explained more variation in seedling communities than rat status. In areas with high seabird burrow density seedling densities were low, especially for the smallest seedlings. Species richness and diversity of seedlings, but not seedling density, were most influenced by changes in microclimate induced by seabirds. Islands where rats had been eradicated or that had low rat populations had the lowest diversity and richness of seedlings (and adults), but the highest seedling density. Seedling communities on these islands were dominated by Pseudopanax lessonii and Coprosma macrocarpa. This indicates lasting effects of rats that may prevent islands from returning to pre-invasion states.

  19. Soil nitrogen gas fluxes during woody legume encroachment: Does encroachment increase gaseous losses?

    NASA Astrophysics Data System (ADS)

    Soper, F.; Groffman, P. M.; Sparks, J. P.

    2014-12-01

    Expansion of nitrogen (N2)-fixing trees is a major driver of ecosystem N enrichment in semi-arid grasslands. During this process, fluxes of N trace gases from soils are likely mediated by interactions between changing soil N availability and primary abiotic biogeochemical drivers in arid systems, namely temperature and wetting/re-wetting dynamics. We investigated the effects of encroachment, season and rainfall dynamics on total reactive N flux (NO, NOy, NH3, N2O) in a sub-tropical, semi-arid Texan savanna encroached by N-fixing Prosopis glandulosa over two years. We compared unencroached upland grasslands and non-fixing woody clusters with continuous Prosopis cover over uplands, intermediate drainages, and playa lowlands. We also quantified denitrification potential of intact soil cores to determine whether N2 could contribute significantly to soil N flux. Substantial soil N enrichment in upland Prosopis groves did not elevate N fluxes above those in remnant grasslands, though lower (moister) landscape positions did exhibit higher total emissions. Along with temperature, soil-wetting dynamics explained the greatest portion of variation in emissions and interacted with vegetation type. Timing and quantity of most recent soil wetting and interval to previous wetting were significant predictors, highlighting the importance of dynamics not captured by soil moisture measurements alone. As with other arid systems, rainfall events after dry periods can stimulate pulse emissions of >400 ug NO-N m-2 h-1. At realistic soil O2 concentrations, N2 fluxes fell below the detection limit of the Nitrogen-Free Atmospheric Recirculation Method system (~11 ug N m-2 h-1). However, applying plausible N2O:N2 flux ratios likely constrains the flux to much lower levels under field conditions. We conclude that encroachment does not increase N fluxes from upland savannas, but that interactions with rainfall and landscape position are important determinants of total emissions.

  20. Leaf structural traits of tropical woody species resistant to cement dust.

    PubMed

    Siqueira-Silva, Advanio Inácio; Pereira, Eduardo Gusmão; Modolo, Luzia Valentina; Paiva, Elder Antonio Sousa

    2016-08-01

    Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60 days, under controlled conditions, with cement dust at 2.5 or 5.0 mg cm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities.

  1. Woody debris volume depletion through decay: implications for biomass and carbon accounting

    USGS Publications Warehouse

    Fraver, Shawn; Milo, Amy M.; Bradford, John B.; D'Amato, Anthony W.; Kenefic, Laura; Palik, Brian J.; Woodall, Christopher W.; Brissette, John

    2013-01-01

    Woody debris decay rates have recently received much attention because of the need to quantify temporal changes in forest carbon stocks. Published decay rates, available for many species, are commonly used to characterize deadwood biomass and carbon depletion. However, decay rates are often derived from reductions in wood density through time, which when used to model biomass and carbon depletion are known to underestimate rate loss because they fail to account for volume reduction (changes in log shape) as decay progresses. We present a method for estimating changes in log volume through time and illustrate the method using a chronosequence approach. The method is based on the observation, confirmed herein, that decaying logs have a collapse ratio (cross-sectional height/width) that can serve as a surrogate for the volume remaining. Combining the resulting volume loss with concurrent changes in wood density from the same logs then allowed us to quantify biomass and carbon depletion for three study species. Results show that volume, density, and biomass follow distinct depletion curves during decomposition. Volume showed an initial lag period (log dimensions remained unchanged), even while wood density was being reduced. However, once volume depletion began, biomass loss (the product of density and volume depletion) occurred much more rapidly than density alone. At the temporal limit of our data, the proportion of the biomass remaining was roughly half that of the density remaining. Accounting for log volume depletion, as demonstrated in this study, provides a comprehensive characterization of deadwood decomposition, thereby improving biomass-loss and carbon-accounting models.

  2. β-Diversity of functional groups of woody plants in a tropical dry forest in Yucatan.

    PubMed

    López-Martínez, Jorge Omar; Sanaphre-Villanueva, Lucía; Dupuy, Juan Manuel; Hernández-Stefanoni, José Luis; Meave, Jorge Arturo; Gallardo-Cruz, José Alberto

    2013-01-01

    correlates that are not apparent when focusing on overall woody plant diversity, and that have important implications for ecological theory and biodiversity conservation.

  3. β-Diversity of Functional Groups of Woody Plants in a Tropical Dry Forest in Yucatan

    PubMed Central

    López-Martínez, Jorge Omar; Sanaphre-Villanueva, Lucía; Dupuy, Juan Manuel; Hernández-Stefanoni, José Luis; Meave, Jorge Arturo; Gallardo-Cruz, José Alberto

    2013-01-01

    correlates that are not apparent when focusing on overall woody plant diversity, and that have important implications for ecological theory and biodiversity conservation. PMID:24040014

  4. Establishment of woody riparian species from natural seedfall at a former gravel pit

    USGS Publications Warehouse

    Roelle, J.E.; Gladwin, D.N.

    1999-01-01

    Establishment of native riparian communities through natural seedfall may be a viable reclamation alternative at some alluvial sand and gravel mines where water level can be controlled in the abandoned pit. We experimented with this approach at a pit in Fort Collins, Colorado, where a drain culvert equipped with a screw gate allows water levels to be manipulated. From 1994 to 1996 we conducted a series of annual drawdowns during the period of natural seedfall of Populus deltoides subsp. monilifera (plains cottonwood), Salix amygdaloides (peachleaf willow), and S. exigua (sand-bar willow), thus providing the bare, moist substrate conducive to establishment of these species. Establishment was highly variable from year to year; in the fall following establishment, frequency of occurrence on 0.5-m2 sample plots ranged from 8.6% to 50.6% for cottonwood, 15.9% to 22.0% for peachleaf willow, and 21.7% to 50.0% for sandbar willow. Mean densities, however, were comparable to those reported for other locations. Concurrent establishment of the undesirable exotic Tamarix ramosissima (saltcedar) was a problem, but we were able to eradicate most saltcedar seedlings by reflooding the lower elevations of the annual drawdown zones each fall. At the end of the 3-year period, at least one of the three native woody species survived on 41.1% of the plots, while saltcedar was present on only 6.1%. In addition to the potential for establishing valuable native habitats, adaptations of the techniques described may require less earth moving than other reclamation approaches.

  5. Individual Species-Area Relationship of Woody Plant Communities in a Heterogeneous Subtropical Monsoon Rainforest

    PubMed Central

    Tsai, Cheng-Han; Lin, Yi-Ching; Wiegand, Thorsten; Nakazawa, Takefumi; Su, Sheng-Hsin

    2015-01-01

    The spatial structure of species richness is often characterized by the species-area relationship (SAR). However, the SAR approach rarely considers the spatial variability of individual plants that arises from species interactions and species’ habitat associations. Here, we explored how the interactions of individual plants of target species influence SAR patterns at a range of neighborhood distances. We analyzed the data of 113,988 woody plants of 110 species from the Fushan Forest Dynamics Plot (25 ha), northern Taiwan, which is a subtropical rainforest heavily influenced by typhoons. We classified 34 dominant species into 3 species types (i.e., accumulator, repeller, or no effect) by testing how the individual species-area relationship (i.e., statistics describing how neighborhood species richness changes around individuals) of target species departs (i.e., positively, negatively, or with no obvious trend) from a null model that accounts for habitat association. Deviation from the null model suggests that the net effect of species’ interactions increases (accumulate) or decreases (repel) neighborhood species richness. We found that (i) accumulators were dominant at small interaction distances (<10–30 m); (ii) the detection of accumulator species was lower at large interaction distances (>30 m); (iii) repellers were rarely detected; and (iv) large-sized and abundant species tended to be accumulators. The findings suggest that positive species interactions have the potential to accumulate neighborhood species richness, particularly through size- and density-dependent mechanisms. We hypothesized that the frequently disturbed environment of this subtropical rainforest (e.g., typhoon-driven natural disturbances such as landslides, soil erosion, flooding, and windthrow) might create the spatial heterogeneity of species richness and promote positive species interactions. PMID:25884405

  6. Physicochemical and sorptive properties of biochars derived from woody and herbaceous biomass.

    PubMed

    Wang, Shengsen; Gao, Bin; Zimmerman, Andrew R; Li, Yuncong; Ma, Lena; Harris, Willie G; Migliaccio, Kati W

    2015-09-01

    It is unclear how the properties of biochar control its ability to sorb metals. In this work, physicochemical properties of a variety of biochars, made from four types of feedstock at three pyrolysis temperatures (300, 450 and 600°C) were compared to their ability to sorb arsenic (As) and lead (Pb) in aqueous solutions. Experimental results showed that both feedstock types and pyrolysis temperature affected biochar's production rate, i.e., ratio of mass of biochar and biomass, thermal stability, elemental composition, non-combustible component (NCC) content, pH values, surface areas and thus their sorption ability to the two metals in aqueous solution. In general, the high temperature biochars had low O/C and H/C ratios, were more carbonized with larger surface area, and were more concentrated with alkaline cations. In addition, biochars made from woody feedstocks had larger surface area, but lower NCC contents than that made from grasses under the same conditions. Although all the tested biochars removed both As and Pb from aqueous solutions, they showed different sorption abilities because of the variations in properties. Statistical analyses suggested that feedstock type affected the sorption ability of the biochars to both As and Pb significantly (p<0.001). Pyrolysis temperature, however, showed little influence on biochar sorption of Pb in aqueous solutions. Statistical analyses also showed that electrostatic interaction played an important role in controlling the sorption of both As(V) and Pb(II) onto the biochar. Other mechanisms, such as precipitation and surface complexation, could also control the sorption of Pb(II) onto the biochars.

  7. Accumulation and Connectivity of Coarse Woody Debris in Partial Harvest and Unmanaged Relict Forests

    PubMed Central

    Morrissey, Robert C.; Jenkins, Michael A.; Saunders, Michael R.

    2014-01-01

    When a tree dies, it continues to play an important ecological role within forests. Coarse woody debris (CWD), including standing deadwood (SDW) and downed deadwood (DDW), is an important functional component of forest ecosystems, particularly for many dispersal-limited saproxylic taxa and for metapopulation dynamics across landscapes. Processes, such as natural disturbance or management, modify forest composition and structure, thereby influencing CWD abundance and distribution. Many studies have compared older forests to forests managed with even-aged silvicultural systems and observed a prolonged period of low CWD occurrence after harvesting. With fine-scale spatial data, our study compares the long-term impacts of light partial harvesting on the CWD structure of eastern deciduous hardwood forests. We mapped and inventoried DDW and SDW using variable radius plots based on a 10 m×10 m grid throughout an unmanaged, structurally-complex relict forest and two nearby forests that were partially harvested over 46 years ago. The relict stand had significantly larger individual pieces and higher accumulations of DDW and SDW than both of the partially harvested stands. Connectivity of CWD was much higher in the relict stand, which had fewer, larger patches. Larger pieces and higher proportion of decay-resistant species (e.g. Quercus spp.) in the relict forest resulted in slower decomposition, greater accumulation and increased connectivity of CWD. Partial harvests, such that occur with selection forestry, are generally considered less disruptive of ecosystem services, but this study highlights the long-term impacts of even light partial harvests on CWD stocks and distribution. When planning harvesting events, forest managers should also consider alternative methods to ensure the sustainability of deadwood resources and function. PMID:25409459

  8. Thermochemical Conversion of Woody Biomass to Fuels and Chemicals Final Report

    SciTech Connect

    Pendse, Hemant P.

    2015-09-30

    Maine and its industries identified more efficient utilization of biomass as a critical economic development issue. In Phase I of this implementation project, a research team was assembled, research equipment was implemented and expertise was demonstrated in pyrolysis, hydrodeoxygenation of pyrolysis oils, catalyst synthesis and characterization, and reaction engineering. Phase II built upon the infrastructure to innovate reaction pathways and process engineering, and integrate new approaches for fuels and chemical production within pulp and paper and other industries within the state. This research cluster brought together chemists, engineers, physicists and students from the University of Maine, Bates College, and Bowdoin College. The project developed collaborations with Oak Ridge National Laboratory and Brookhaven National Laboratory. The specific research projects within this proposal were of critical interest to the DoE - in particular the biomass program within EERE and the catalysis/chemical transformations program within BES. Scientific and Technical Merit highlights of this project included: (1) synthesis and physical characterization of novel size-selective catalyst/supports using engineered mesoporous (1-10 nm diameter pores) materials, (2) advances in fundamental knowledge of novel support/ metal catalyst systems tailored for pyrolysis oil upgrading, (3) a microcalorimetric sensing technique, (4) improved methods for pyrolysis oil characterization, (5) production and characterization of woody biomass-derived pyrolysis oils, (6) development of two new patented bio oil pathways: thermal deoxygenation (TDO) and formate assisted pyrolysis (FASP), and (7) technoeconomics of pyrolysis of Maine forest biomass. This research cluster has provided fundamental knowledge to enable and assess pathways to thermally convert biomass to hydrocarbon fuels and chemicals.

  9. Accumulation and connectivity of coarse woody debris in partial harvest and unmanaged relict forests.

    PubMed

    Morrissey, Robert C; Jenkins, Michael A; Saunders, Michael R

    2014-01-01

    When a tree dies, it continues to play an important ecological role within forests. Coarse woody debris (CWD), including standing deadwood (SDW) and downed deadwood (DDW), is an important functional component of forest ecosystems, particularly for many dispersal-limited saproxylic taxa and for metapopulation dynamics across landscapes. Processes, such as natural disturbance or management, modify forest composition and structure, thereby influencing CWD abundance and distribution. Many studies have compared older forests to forests managed with even-aged silvicultural systems and observed a prolonged period of low CWD occurrence after harvesting. With fine-scale spatial data, our study compares the long-term impacts of light partial harvesting on the CWD structure of eastern deciduous hardwood forests. We mapped and inventoried DDW and SDW using variable radius plots based on a 10 m × 10 m grid throughout an unmanaged, structurally-complex relict forest and two nearby forests that were partially harvested over 46 years ago. The relict stand had significantly larger individual pieces and higher accumulations of DDW and SDW than both of the partially harvested stands. Connectivity of CWD was much higher in the relict stand, which had fewer, larger patches. Larger pieces and higher proportion of decay-resistant species (e.g. Quercus spp.) in the relict forest resulted in slower decomposition, greater accumulation and increased connectivity of CWD. Partial harvests, such that occur with selection forestry, are generally considered less disruptive of ecosystem services, but this study highlights the long-term impacts of even light partial harvests on CWD stocks and distribution. When planning harvesting events, forest managers should also consider alternative methods to ensure the sustainability of deadwood resources and function.

  10. Meta-analysis of susceptibility of woody plants to loss of genetic diversity through habitat fragmentation.

    PubMed

    Vranckx, Guy; Jacquemyn, Hans; Muys, Bart; Honnay, Olivier

    2012-04-01

    Shrubs and trees are assumed less likely to lose genetic variation in response to habitat fragmentation because they have certain life-history characteristics such as long lifespans and extensive pollen flow. To test this assumption, we conducted a meta-analysis with data on 97 woody plant species derived from 98 studies of habitat fragmentation. We measured the weighted response of four different measures of population-level genetic diversity to habitat fragmentation with Hedge's d and Spearman rank correlation. We tested whether the genetic response to habitat fragmentation was mediated by life-history traits (longevity, pollination mode, and seed dispersal vector) and study characteristics (genetic marker and plant material used). For both tests of effect size habitat fragmentation was associated with a substantial decrease in expected heterozygosity, number of alleles, and percentage of polymorphic loci, whereas the population inbreeding coefficient was not associated with these measures. The largest proportion of variation among effect sizes was explained by pollination mechanism and by the age of the tissue (progeny or adult) that was genotyped. Our primary finding was that wind-pollinated trees and shrubs appeared to be as likely to lose genetic variation as insect-pollinated species, indicating that severe habitat fragmentation may lead to pollen limitation and limited gene flow. In comparison with results of previous meta-analyses on mainly herbaceous species, we found trees and shrubs were as likely to have negative genetic responses to habitat fragmentation as herbaceous species. We also found that the genetic variation in offspring was generally less than that of adult trees, which is evidence of a genetic extinction debt and probably reflects the genetic diversity of the historical, less-fragmented landscape.

  11. Ecological and Geochemical Assessment of Woody Vegetation in Tungsten-Molybdenum Mining Area (Buryat Republic, Russia)

    NASA Astrophysics Data System (ADS)

    Kasimov, N. S.; Kosheleva, N. E.; Timofeev, I. V.

    2016-08-01

    Biogeochemical studies performed in the impact zone of the Dzhida tungsten- molybdenum mining and processing enterprise in Zakamensk (Buryat Republic, Russia) in 2013 showed that the needles and bark of Lárix sibírica Ledeb. and the leaves and bark of Bétula platyphýlla Sukacs are characterized by certain changes in their trace element (TE) composition. The total index of the biogeochemical transformation Z v which sums all the positive and negative deviations of TE contents from the background values for larch and birch in the city averaged 95 and 46 for their assimilating organs and 30 and 25 for their perennial organs, respectively. This was caused by the increased uptake of W, Mo, V, Pb, Bi, Cd, and Co in the city. The close correlation between TE concentrations in soils and plants was observed for the elements of the strong and moderate biological capturing, including cationic Cu, Zn, Sr, Cd, and Ba and anions of the ore elements W and Mo and the associated Bi. The most intensive TE accumulation was found in the larch needles due to the wax layer which firmly fixes the dust enriched with TEs. Indication of the ecological state of urban woody plants revealed that their organs contain the increased concentrations of Pb and Fe and suffer from the Mn deficiency, which attests to disturbance of photosynthetic processes, most pronounced in the residential area. Birch leaves are characterized by a very low Cu/Zn ratio which detects the imbalance of these elements participating in the synthesis of enzymes.

  12. The influence of woody encroachment on the nitrogen cycle: fixation, storage and gas loss

    NASA Astrophysics Data System (ADS)

    Soper, F.; Sparks, J. P.

    2015-12-01

    Woody encroachment is a pervasive land cover change throughout the tropics and subtropics. Encroachment is frequently catalyzed by nitrogen (N)-fixing trees and the resulting N inputs potentially alter whole-ecosystem N cycling, accumulation and loss. In the southern US, widespread encroachment by legume Prosopis glandulosa is associated with increased soil total N storage, inorganic N concentrations, and net mineralization and nitrification rates. To better understand the effects of this process on ecosystem N cycling, we investigated patterns of symbiotic N fixation, N accrual and soil N trace gas and N2 emissions during Prosopis encroachment into the southern Rio Grande Plains. Analyses of d15N in foliage, xylem sap and plant-available soil N suggested that N fixation rates increase with tree age and are influenced by abiotic conditions. A model of soil N accrual around individual trees, accounting for atmospheric inputs and gas losses, generates lifetimes N fixation estimates of up to 9 kg for a 100-year-old tree and current rates of 7 kg N ha-1 yr-1. However, these N inputs and increased soil cycling rates do not translate into increased N gas losses. Two years of field measurements of a complete suite of N trace gases (ammonia, nitrous oxide, nitric oxide and other oxidized N compounds) found no difference in flux between upland Prosopis groves and adjacent unencroached grasslands. Total emissions for both land cover types average 0.56-0.65 kg N ha-1 yr-1, comparable to other southern US grasslands. Additional lab experiments suggested that N2 losses are low and that field oxygen conditions are not usually conducive to denitrification. Taken together, results suggest that this ecosystem is currently experiencing a period of net N accrual under ongoing encroachment.

  13. Nitrogen trace gas fluxes from a semiarid subtropical savanna under woody legume encroachment

    NASA Astrophysics Data System (ADS)

    Soper, Fiona M.; Boutton, Thomas W.; Groffman, Peter M.; Sparks, Jed P.

    2016-05-01

    Savanna ecosystems are a major source of nitrogen (N) trace gases that influence air quality and climate. These systems are experiencing widespread encroachment by woody plants, frequently associated with large increases in soil N, with no consensus on implications for trace gas emissions. We investigated the impact of encroachment by N-fixing tree Prosopis glandulosa on total reactive N gas flux (Nt = NO + N2O + NOy + NH3) from south Texas savanna soils over 2 years. Contrary to expectations, upland Prosopis groves did not have greater Nt fluxes than adjacent unencroached grasslands. However, abiotic conditions (temperature, rainfall, and topography) were strong drivers. Emissions from moist, low-lying Prosopis playas were up to 3 times higher than from Prosopis uplands. Though NO dominated emissions, NH3 and NOy (non-NO oxidized N) comprised 12-16% of the total summer N flux (up to 7.9 µg N m-2 h-1). Flux responses to soil wetting were temperature dependent for NO, NH3, and NOy: a 15 mm rainfall event increased flux 3-fold to 22-fold after 24 h in summer but had no effect in winter. Repeated soil wetting reduced N flux responses, indicating substrate depletion as a likely control. Rapid (<1 min) increases in NO emissions following wetting of dry soils suggested that abiotic chemodenitrification contributes to pulse emissions. We conclude that temperature and wetting dynamics, rather than encroachment, are primary drivers of N flux from these upland savannas, with implications for future emission patterns under altered precipitation regimes.

  14. Electrophysiological assessment of water stress in fruit-bearing woody plants.

    PubMed

    Ríos-Rojas, Liliana; Tapia, Franco; Gurovich, Luis A

    2014-06-15

    Development and evaluation of a real-time plant water stress sensor, based on the electrophysiological behavior of fruit-bearing woody plants is presented. Continuous electric potentials are measured in tree trunks for different irrigation schedules, inducing variable water stress conditions; results are discussed in relation to soil water content and micro-atmospheric evaporative demand, determined continuously by conventional sensors, correlating this information with tree electric potential measurements. Systematic and differentiable patterns of electric potentials for water-stressed and no-stressed trees in 2 fruit species are presented. Early detection and recovery dynamics of water stress conditions can also be monitored with these electrophysiology sensors, which enable continuous and non-destructive measurements for efficient irrigation scheduling throughout the year. The experiment is developed under controlled conditions, in Faraday cages located at a greenhouse area, both in Persea americana and Prunus domestica plants. Soil moisture evolution is controlled using capacitance sensors and solar radiation, temperature, relative humidity, wind intensity and direction are continuously registered with accurate weather sensors, in a micro-agrometeorological automatic station located at the experimental site. The electrophysiological sensor has two stainless steel electrodes (measuring/reference), inserted on the stem; a high precision Keithley 2701 digital multimeter is used to measure plant electrical signals; an algorithm written in MatLab(®), allows correlating the signal to environmental variables. An electric cyclic behavior is observed (circadian cycle) in the experimental plants. For non-irrigated plants, the electrical signal shows a time positive slope and then, a negative slope after restarting irrigation throughout a rather extended recovery process, before reaching a stable electrical signal with zero slope. Well-watered plants presented a

  15. Potential for water salvage by removal of non-native woody vegetation from dryland river systems

    USGS Publications Warehouse

    Doody, T.M.; Nagler, P.L.; Glenn, E.P.; Moore, G.W.; Morino, K.; Hultine, K.R.; Benyon, R.G.

    2011-01-01

    Globally, expansion of non-native woody vegetation across floodplains has raised concern of increased evapotranspiration (ET) water loss with consequent reduced river flows and groundwater supplies. Water salvage programs, established to meet water supply demands by removing introduced species, show little documented evidence of program effectiveness. We use two case studies in the USA and Australia to illustrate factors that contribute to water salvage feasibility for a given ecological setting. In the USA, saltcedar (Tamarix spp.) has become widespread on western rivers, with water salvage programs attempted over a 50-year period. Some studies document riparian transpiration or ET reduction after saltcedar removal, but detectable increases in river base flow are not conclusively shown. Furthermore, measurements of riparian vegetation ET in natural settings show saltcedar ET overlaps the range measured for native riparian species, thereby constraining the possibility of water salvage by replacing saltcedar with native vegetation. In Australia, introduced willows (Salix spp.) have become widespread in riparian systems in the Murray-Darling Basin. Although large-scale removal projects have been undertaken, no attempts have been made to quantify increases in base flows. Recent studies of ET indicate that willows growing in permanently inundated stream beds have high transpiration rates, indicating water savings could be achieved from removal. In contrast, native Eucalyptus trees and willows growing on stream banks show similar ET rates with no net water salvage from replacing willows with native trees. We conclude that water salvage feasibility is highly dependent on the ecohydrological setting in which the non-native trees occur. We provide an overview of conditions favorable to water salvage. Copyright ?? 2011 John Wiley & Sons, Ltd.

  16. Species-Specific Effects of Woody Litter on Seedling Emergence and Growth of Herbaceous Plants

    PubMed Central

    Koorem, Kadri; Price, Jodi N.; Moora, Mari

    2011-01-01

    The effect of litter on seedling establishment can influence species richness in plant communities. The effect of litter depends on amount, and also on litter type, but relatively little is known about the species-specific effects of litter. We conducted a factorial greenhouse experiment to examine the effect of litter type, using two woody species that commonly co-occur in boreonemoral forest—evergreen spruce (Picea abies), deciduous hazel (Corylus avellana), and a mixture of the two species—and litter amount—shallow (4 mm), deep (12 mm) and leachate—on seedling emergence and biomass of three understorey species. The effect of litter amount on seedling emergence was highly dependent on litter type; while spruce needle litter had a significant negative effect that increased with depth, seedling emergence in the presence of hazel broadleaf litter did not differ from control pots containing no litter. Mixed litter of both species also had a negative effect on seedling emergence that was intermediate compared to the single-species treatments. Spruce litter had a marginally positive (shallow) or neutral effect (deep) on seedling biomass, while hazel and mixed litter treatments had significant positive effects on biomass that increased with depth. We found non-additive effects of litter mixtures on seedling biomass indicating that high quality hazel litter can reduce the negative effects of spruce. Hazel litter does not inhibit seedling emergence; it increases seedling growth, and creates better conditions for seedling growth in mixtures by reducing the suppressive effect of spruce litter, having a positive effect on understorey species richness. PMID:22028890

  17. Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

    NASA Astrophysics Data System (ADS)

    Máguas, C.; Rascher, K. G.; Martins-Loução, A.; Carvalho, P.; Pinho, P.; Ramos, M.; Correia, O.; Werner, C.

    2011-02-01

    In spite of the relative importance of groundwater in coastal dune systems, the number of studies concerning the responsiveness of vegetation to ground water (GW) variability, in particularly in Mediterranean regions, is scarce. In this study, we established 5 study sites within a meso-mediterranean sand dune Pinus pinaster forest on the Atlantic coast of Portugal, taking advantage of natural topographic variability and artificial GW exploitation, which resulted in substantial variability in depth to GW between microsites. Here we identify the degree of usage and dependence on GW of different plant functional groups (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader) and how GW dependence varied seasonally and between the heterogeneous microsites. Our results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy). The species comparison revealed that variability in pre-dawn water potential (Ψpre) and bulk leaf δ13C was related to microsite differences in GW use in deep-rooted (Pinus pinaster, Myrica faya) and phreatophyte (Salix repens) species. However, such variation was more evident during spring rather than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understorey drought adapted shrub, across seasons and microsites seemed to be independent of water availability. Thus, the susceptibility to changing GW availability in sand dune plant species is variable, being particularly relevant for deep rooted species and phreatophytes, which have typically been less exposed to GW fluctuations.

  18. Not all droughts are created equal: translating meteorological drought into woody plant mortality.

    PubMed

    Anderegg, Leander D L; Anderegg, William R L; Berry, Joseph A

    2013-07-01

    Widespread drought-induced mortality of woody plants has recently occurred worldwide, is likely to be exacerbated by future climate change and holds large ecological consequences. Yet despite decades of research on plant-water relations, the pathways through which drought causes plant mortality are poorly understood. Recent work on the physiology of tree mortality has begun to reveal how physiological dysfunction induced by water stress leads to plant death; however, we are still far from being able to predict tree mortality using easily observed or modeled meteorological variables. In this review, we contend that, in order to fully understand when and where plants will exceed mortality thresholds when drought occurs, we must understand the entire path by which precipitation deficit is translated into physiological dysfunction and lasting physiological damage. In temperate ecosystems with seasonal climate patterns, precipitation characteristics such as seasonality, timing, form (snow versus rain) and intensity interact with edaphic characteristics to determine when and how much water is actually available to plants as soil moisture. Plant and community characteristics then mediate how quickly water is used and seasonally varying plant physiology determines whether the resulting soil moisture deficit is physiologically damaging. Recent research suggests that drought seasonality and timing matter for how an ecosystem experiences drought. But, mortality studies that bridge the gaps between climatology, hydrology, plant ecology and plant physiology are rare. Drawing upon a broad hydrological and ecological perspective, we highlight key and underappreciated processes that may mediate drought-induced tree mortality and propose steps to better include these components in current research.

  19. Wildfire Induced Degradation of Woody Vegetation in Dry Zone of Kazakhstan

    NASA Astrophysics Data System (ADS)

    Terekhov, A.

    2011-08-01

    Small bushy tree species dominate the semi-arid areas of Kazakhstan. In the course of their life cycle, they form a layer of litter that is resistant to wind transport. This small shrub species with its own litter play a significant role in the spectral characteristics of the Earth surface. Changes in the density of shrub canopy forms or replacing them with herbaceous species is accompanied by significant changes in the spectral characteristics in the visible and near infrared spectral bands in the autumn. These changes can be recorded from satellite data. LANDSAT-TM images during 1985-2007 years and MODIS data (USGS: MOD09Q1, 2000-2010) used to diagnose changes in relation between woodyherbaceous vegetation species in the dry zone of Kazakhstan. It was found that over the past 10 years, spreading small shrub forms of semi-arid vegetation significantly decreased. There is a persistent expansion of herbal forms, leading to the semi-steppe formation areas. The mechanism of repression of wood forms constructed through the accumulation of dry plant mass during wet years, with its subsequent burnout during wildfires. In the case of a strong fire, a complete destruction of species is observed. The restoration of small shrub cover demands more than 20 years. Comparative analysis of LANDSAT-TM images showed a 10 times increasing of the fire scar areas in the test area in the central part of Kazakhstan between 1985 and 2007. According MOD09Q1 was conducted mapping small shrub forms of degradation in Kazakhstan. Reducing the area occupied by woody vegetation, semi-desert was about 30 million hectares or over 30% of their total range in Kazakhstan.

  20. Methane Emissions from Woody Stems of Tropical and Temperate Wetland Trees

    NASA Astrophysics Data System (ADS)

    Pangala, S. R.; Hornibrook, E. R.; Gowing, D. J.; Bastviken, D.; Enrich-Prast, A.; Gauci, V.

    2013-12-01

    Wetland-adapted trees are known to transport and release soil-produced methane to the atmosphere through woody stem surfaces, yet the magnitude and controls of tree-mediated methane emissions remain unknown for mature forests. Although 60% of global wetlands are forested, and many tropical forests are either permanently or seasonally flooded, the ecosystem level contribution of tree-mediated methane flux relative to other gas transport pathways (e.g., ebullition, pore-water diffusion and via aerenchyma of herbaceous plants) has received limited attention. The role of trees as a conduit for methane export from soil to the atmosphere was assessed in situ in a temperate forested wetland (Flitwick Moor, UK) and tropical forested wetlands in Borneo, Indonesia and Amazonia, Brazil. Mesocosm experiments also were conducted in the temperate region to characterise emission characteristics of Alnus glutinosa saplings subjected to different water-table treatments. Methane emissions from trees were compared to fluxes from the soil surface in both the in situ and mesocosm studies. Temperate and tropical tree species both released significant quantities of methane from stem surfaces. Emission rates for young trees exceeded that of mature trees by several orders of magnitude on a stem surface area basis. Key factors controlling rates of tree-mediated flux were tree physiology (e.g., wood specific density, stem lenticel density), abiotic conditions (e.g., soil temperature) and methane gas transport mechanisms (e.g., passive diffusion, convective transport). Tree-mediated methane emissions contributed 6 to 87% of total ecosystem methane flux with the largest relative contribution from trees occurring in tropical wetlands. Recent data from Amazonian wetlands demonstrate very high rates of tree-mediated methane emission relative to other types of forested wetlands. These results indicate that exclusion of tree-mediated methane fluxes from measurement campaigns conducted in forested

  1. A synthesis of postfire recovery traits of woody plants in Australian ecosystems.

    PubMed

    Clarke, Peter J; Lawes, Michael J; Murphy, Brett P; Russell-Smith, Jeremy; Nano, Catherine E M; Bradstock, Ross; Enright, Neal J; Fontaine, Joseph B; Gosper, Carl R; Radford, Ian; Midgley, Jeremy J; Gunton, Richard M

    2015-11-15

    Postfire resprouting and recruitment from seed are key plant life-history traits that influence population dynamics, community composition and ecosystem function. Species can have one or both of these mechanisms. They confer resilience, which may determine community composition through differential species persistence after fire. To predict ecosystem level responses to changes in climate and fire conditions, we examined the proportions of these plant fire-adaptive traits among woody growth forms of 2880 taxa, in eight fire-prone ecosystems comprising ~87% of Australia's land area. Shrubs comprised 64% of the taxa. More tree (>84%) than shrub (~50%) taxa resprouted. Basal, epicormic and apical resprouting occurred in 71%, 22% and 3% of the taxa, respectively. Most rainforest taxa (91%) were basal resprouters. Many trees (59%) in frequently-burnt eucalypt forest and savanna resprouted epicormically. Although crown fire killed many mallee (62%) and heathland (48%) taxa, fire-cued seeding was common in these systems. Postfire seeding was uncommon in rainforest and in arid Acacia communities that burnt infrequently at low intensity. Resprouting was positively associated with ecosystem productivity, but resprouting type (e.g. basal or epicormic) was associated with local scale fire activity, especially fire frequency. Although rainforest trees can resprout they cannot recruit after intense fires and may decline under future fires. Semi-arid Acacia communities would be susceptible to increasing fire frequencies because they contain few postfire seeders. Ecosystems dominated by obligate seeders (mallee, heath) are also susceptible because predicted shorter inter-fire intervals will prevent seed bank accumulation. Savanna may be resilient to future fires because of the adaptive advantage of epicormic resprouting among the eucalypts. The substantial non-resprouting shrub component of shrublands may decline, but resilient Eucalyptus spp. will continue to dominate under future

  2. Mapping aboveground woody biomass using forest inventory, remote sensing and geostatistical techniques.

    PubMed

    Yadav, Bechu K V; Nandy, S

    2015-05-01

    Mapping forest biomass is fundamental for estimating CO₂ emissions, and planning and monitoring of forests and ecosystem productivity. The present study attempted to map aboveground woody biomass (AGWB) integrating forest inventory, remote sensing and geostatistical techniques, viz., direct radiometric relationships (DRR), k-nearest neighbours (k-NN) and cokriging (CoK) and to evaluate their accuracy. A part of the Timli Forest Range of Kalsi Soil and Water Conservation Division, Uttarakhand, India was selected for the present study. Stratified random sampling was used to collect biophysical data from 36 sample plots of 0.1 ha (31.62 m × 31.62 m) size. Species-specific volumetric equations were used for calculating volume and multiplied by specific gravity to get biomass. Three forest-type density classes, viz. 10-40, 40-70 and >70% of Shorea robusta forest and four non-forest classes were delineated using on-screen visual interpretation of IRS P6 LISS-III data of December 2012. The volume in different strata of forest-type density ranged from 189.84 to 484.36 m(3) ha(-1). The total growing stock of the forest was found to be 2,024,652.88 m(3). The AGWB ranged from 143 to 421 Mgha(-1). Spectral bands and vegetation indices were used as independent variables and biomass as dependent variable for DRR, k-NN and CoK. After validation and comparison, k-NN method of Mahalanobis distance (root mean square error (RMSE) = 42.25 Mgha(-1)) was found to be the best method followed by fuzzy distance and Euclidean distance with RMSE of 44.23 and 45.13 Mgha(-1) respectively. DRR was found to be the least accurate method with RMSE of 67.17 Mgha(-1). The study highlighted the potential of integrating of forest inventory, remote sensing and geostatistical techniques for forest biomass mapping.

  3. Climate change and shifts in spring phenology of three horticultural woody perennials in northeastern USA

    NASA Astrophysics Data System (ADS)

    Wolfe, David W.; Schwartz, Mark D.; Lakso, Alan N.; Otsuki, Yuka; Pool, Robert M.; Shaulis, Nelson J.

    2005-05-01

    We evaluated spring phenology changes from 1965 to 2001 in northeastern USA utilizing a unique data set from 72 locations with genetically identical lilac plants (Syringa chinensis, clone “Red Rothomagensis”). We also utilized a previously validated lilac-honeysuckle “spring index” model to reconstruct a more complete record of first leaf date (FLD) and first flower date (FFD) for the region from historical weather data. In addition, we examined mid-bloom dates for apple (Malus domestica) and grape (Vitis vinifera) collected at several sites in the region during approximately the same time period. Almost all lilac sites with significant linear trends for FLD or FFD versus year had negative slopes (advanced development). Regression analysis of pooled data for the 72 sites indicated an advance of -0.092 day/year for FFD (P=0.003). The slope for FLD was also negative (-0.048 day/year), but not significant (P=0.234). The simulated data from the “spring index” model, which relies on local daily temperature records, indicated highly significant (P<0.001) negative slopes of -0.210 and -0.123 day/year for FLD and FFD, respectively. Data collected for apple and grape also indicated advance spring development, with slopes for mid-bloom date versus year of -0.20 day/year (P=0.01) and -0.146 (P=0.14), respectively. Collectively, these results indicate an advance in spring phenology ranging from 2 to 8 days for these woody perennials in northeastern USA for the period 1965 to 2001, qualitatively consistent with a warming trend, and consistent with phenology shifts reported for other mid- and high-latitude regions.

  4. Altering recharge dynamics through woody vegetation removal: a study on the Carrizo-Wilcox aquifer of south Texas

    NASA Astrophysics Data System (ADS)

    Mattox, A. M.

    2011-12-01

    Grasslands in many semi-arid regions of the world have seen an expansion of woody vegetation over the past century and many now exist largely as woodlands or shrublands. This "woody encroachment" results in numerous changes to ecosystem function, including alteration of element and water cycles. As in many parts of the world, these shrublands in south Texas have been subjected to a variety of management practices intended to reduce woody vegetation and increase the dominance of herbaceous vegetation. In addition to the intended change in vegetation structure, this activity has the potential to affect hydrologic fluxes and potentially increase deep drainage through reduced transpiration and rooting depths. However, there is significant uncertainty about the hydrologic response of vegetation to woody vegetation removal. We report here the results of a large manipulative experiment designed to assess the effects of woody vegetation removal on soil moisture movement in the vadose zone in an area that serves as a recharge zone for an unconsolidated sediment aquifer (Carrizo-Wilcox). In this study woody vegetation has been removed using a mechanical method (roller chopping) as well as a mechanical and chemical method (chainsaw removal + stump herbicide). The treated plots are located on three different soil types that represent the range of soils typical in this area. A water balance approach is used to assess soil moisture fluxes and potential deep drainage. In this first year of the study we quantified ecological and edaphic components that have the greatest effect on deep drainage, namely rooting depth, soil texture and antecedent soil water conditions. Exceptionally dry conditions this year have provided a unique opportunity to understand plant soil water interactions in the critical zone given the strong soil moisture limitations observed in the surface soil horizons. Understanding these interactions across different plant communities and soil textures are the

  5. Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) Synthetic Aperture Radar data

    NASA Astrophysics Data System (ADS)

    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Kleynhans, Waldo; Wessels, Konrad; Asner, Gregory; Leblon, Brigitte

    2015-07-01

    Structural parameters of the woody component in African savannahs provide estimates of carbon stocks that are vital to the understanding of fuelwood reserves, which is the primary source of energy for 90% of households in South Africa (80% in Sub-Saharan Africa) and are at risk of over utilisation. The woody component can be characterised by various quantifiable woody structural parameters, such as tree cover, tree height, above ground biomass (AGB) or canopy volume, each been useful for different purposes. In contrast to the limited spatial coverage of ground-based approaches, remote sensing has the ability to sense the high spatio-temporal variability of e.g. woody canopy height, cover and biomass, as well as species diversity and phenological status - a defining but challenging set of characteristics typical of African savannahs. Active remote sensing systems (e.g. Light Detection and Ranging - LiDAR; Synthetic Aperture Radar - SAR), on the other hand, may be more effective in quantifying the savannah woody component because of their ability to sense within-canopy properties of the vegetation and its insensitivity to atmosphere and clouds and shadows. Additionally, the various components of a particular target's structure can be sensed differently with SAR depending on the frequency or wavelength of the sensor being utilised. This study sought to test and compare the accuracy of modelling, in a Random Forest machine learning environment, woody above ground biomass (AGB), canopy cover (CC) and total canopy volume (TCV) in South African savannahs using a combination of X-band (TerraSAR-X), C-band (RADARSAT-2) and L-band (ALOS PALSAR) radar datasets. Training and validation data were derived from airborne LiDAR data to evaluate the SAR modelling accuracies. It was concluded that the L-band SAR frequency was more effective in the modelling of the CC (coefficient of determination or R2 of 0.77), TCV (R2 of 0.79) and AGB (R2 of 0.78) metrics in Southern African

  6. Satellite- and pollen-based quantitative woody cover reconstructions for northern Asia: Verification and application to late-Quaternary pollen data

    NASA Astrophysics Data System (ADS)

    Tarasov, Pavel; Williams, John W.; Andreev, Andrei; Nakagawa, Takeshi; Bezrukova, Elena; Herzschuh, Ulrike; Igarashi, Yaeko; Müller, Stefanie; Werner, Kirstin; Zheng, Zhuo

    2007-12-01

    Accurate reconstruction of late-Quaternary vegetation cover is necessary for better understanding of past vegetation dynamics, the role of vegetation feedbacks in glacial-interglacial climate variations, and for validating vegetation and climate models. In this paper over 1700 surface-pollen spectra from the former Soviet Union, Mongolia, northern China, and northern Japan together with data from the Advanced Very High Resolution Radiometer (AVHRR) were used to calibrate modern-analogue method for quantitatively reconstructing past woody cover from fossil pollen data. The AVHRR-based estimates of woody cover percentages within a 21 × 21 km window around pollen sampling sites were attributed to the respective modern pollen spectra. Reconstructions of modern woody cover using the pollen data and best-modern-analogues (BMA) method matched well to the original AVHRR-based estimates, for both total woody cover ( r2 = 0.77) and its fractions, including broad-leaved ( r2 = 0.66), needle-leaved ( r2 = 0.79), deciduous ( r2 = 0.60) and evergreen ( r2 = 0.76) woody cover. Discrepancies in the pollen-AVHRR cross-validation may be caused by long-distance transport of arboreal pollen, patchy forest distributions, underrepresentation of Larix and Populus in pollen records, and errors in the AVHRR classification. The generally strong correlations encourage application of the modern-analogue approach for reconstructing late-Quaternary variations in vegetation cover from northern Asian fossil pollen records. At the last glacial maximum (LGM: ˜ 21,000 cal yr BP), areas presently occupied by boreal forest were much more open, suggesting a reduction in total woody cover to below 20% at most modern forest sites. Pollen records from northern and central Siberia suggest a rather quick spread of tree and shrub vegetation after 15,000 cal yr BP, presumably in response to increased summer insolation. Woody cover histories are spatially variable in the modern forest-steppe, where tree

  7. A conceptual framework for dryland aeolian sediment transport along the grassland-forest continuum: Effects of woody plant canopy cover and disturbance

    NASA Astrophysics Data System (ADS)

    Breshears, David D.; Whicker, Jeffrey J.; Zou, Chris B.; Field, Jason P.; Allen, Craig D.

    2009-04-01

    Aeolian processes are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation. Dryland ecosystems include grassland, shrubland, savanna, woodland, and forest, and can be viewed collectively as a continuum of woody plant cover spanning from grasslands with no woody plant cover up to forests with nearly complete woody plant cover. Along this continuum, the spacing and shape of woody plants determine the spatial density of roughness elements, which directly affects aeolian sediment transport. Despite the extensiveness of dryland ecosystems, studies of aeolian sediment transport have generally focused on agricultural fields, deserts, or highly disturbed sites where rates of transport are likely to be greatest. Until recently, few measurements have been made of aeolian sediment transport over multiple wind events and across a variety of types of dryland ecosystems. To evaluate potential trends in aeolian sediment transport as a function of woody plant cover, estimates of aeolian sediment transport from recently published studies, in concert with rates from four additional locations (two grassland and two woodland sites), are reported here. The synthesis of these reports leads to the development of a new conceptual framework for aeolian sediment transport in dryland ecosystems along the grassland-forest continuum. The findings suggest that: (1) for relatively undisturbed ecosystems, shrublands have inherently greater aeolian sediment transport because of wake interference flow associated with intermediate levels of density and spacing of woody plants; and (2) for disturbed ecosystems, the upper bound for aeolian sediment transport decreases as a function of increasing amounts of woody plant cover because of the effects of the height and density of the canopy on airflow patterns and ground cover associated with woody plant cover. Consequently, aeolian sediment transport following disturbance spans the largest

  8. A conceptual framework for dryland aeolian sediment transport along the grassland-forest continuum: Effects of woody plant canopy cover and disturbance

    USGS Publications Warehouse

    Breshears, D.D.; Whicker, J.J.; Zou, C.B.; Field, J.P.; Allen, C.D.

    2009-01-01

    Aeolian processes are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation. Dryland ecosystems include grassland, shrubland, savanna, woodland, and forest, and can be viewed collectively as a continuum of woody plant cover spanning from grasslands with no woody plant cover up to forests with nearly complete woody plant cover. Along this continuum, the spacing and shape of woody plants determine the spatial density of roughness elements, which directly affects aeolian sediment transport. Despite the extensiveness of dryland ecosystems, studies of aeolian sediment transport have generally focused on agricultural fields, deserts, or highly disturbed sites where rates of transport are likely to be greatest. Until recently, few measurements have been made of aeolian sediment transport over multiple wind events and across a variety of types of dryland ecosystems. To evaluate potential trends in aeolian sediment transport as a function of woody plant cover, estimates of aeolian sediment transport from recently published studies, in concert with rates from four additional locations (two grassland and two woodland sites), are reported here. The synthesis of these reports leads to the development of a new conceptual framework for aeolian sediment transport in dryland ecosystems along the grassland-forest continuum. The findings suggest that: (1) for relatively undisturbed ecosystems, shrublands have inherently greater aeolian sediment transport because of wake interference flow associated with intermediate levels of density and spacing of woody plants; and (2) for disturbed ecosystems, the upper bound for aeolian sediment transport decreases as a function of increasing amounts of woody plant cover because of the effects of the height and density of the canopy on airflow patterns and ground cover associated with woody plant cover. Consequently, aeolian sediment transport following disturbance spans the largest

  9. Woody biomass: Niche position as a source of sustainable renewable chemicals and energy and kinetics of hot-water extraction/hydrolysis.

    PubMed

    Liu, Shijie

    2010-01-01

    The conversion of biomass to chemicals and energy is imperative to sustaining our way of life as known to us today. Fossil chemical and energy sources are traditionally regarded as wastes from a distant past. Petroleum, natural gas, and coal are not being regenerated in a sustainable manner. However, biomass sources such as algae, grasses, bushes and forests are continuously being replenished. Woody biomass represents the most abundant and available biomass source. Woody biomass is a reliably sustainable source of chemicals and energy that could be replenished at a rate consistent with our needs. The biorefinery is a concept describing the collection of processes used to convert biomass to chemicals and energy. Woody biomass presents more challenges than cereal grains for conversion to platform chemicals due to its stereochemical structures. Woody biomass can be thought of as comprised of at least four components: extractives, hemicellulose, lignin and cellulose. Each of these four components has a different degree of resistance to chemical, thermal and biological degradation. The biorefinery concept proposed at ESF (State University of New York - College of Environmental Science and Forestry) aims at incremental sequential deconstruction, fractionation/conversion of woody biomass to achieve efficient separation of major components. The emphasis of this work is on the kinetics of hot-water extraction, filling the gap in the fundamental understanding, linking engineering developments, and completing the first step in the biorefinery processes. This first step removes extractives and hemicellulose fractions from woody biomass. While extractives and hemicellulose are largely removed in the extraction liquor, cellulose and lignin largely remain in the residual woody structure. Xylo-oligomers and acetic acid in the extract are the major components having the greatest potential value for development. Extraction/hydrolysis involves at least 16 general reactions that could

  10. A mixed-methods approach to understanding farmer and rancher interest in supplying woody biomass in the U.S. Northern Great Plains

    NASA Astrophysics Data System (ADS)

    Hand, Ashley M.

    Bioenergy produced from cellulosic feedstocks could serve as an opportunity to strengthen local and regional economies, reduce fossil fuel energy consumption for transportation or electricity production, and also jointly produce various environmental services. In the U.S. Northern Great Plains, woody bioenergy crops can provide multifunctional benefits while building biomass supply capacity when established within existing farm and ranch systems. Understanding what facilitates or constraints potential biomass suppliers' level of interest in biomass production is essential to fully assess the regional potential of biomass-based bioenergy in the Northern Great Plains. Qualitative data from a regional focus group series illustrates the complexities associated with farmer definitions of marginality, attitudes towards trees and bioenergy production, while also characterizing influences on farmer/rancher interest in woody biomass production. Quantitatively, a region-wide representative survey of farmers and ranchers managing marginal land captures a snapshot of operator interest in woody biomass production. Results indicate that 61% of farmers and ranchers have some degree of interest in woody biomass production, while results from an ordered probit regression further illustrate how farm/ranch system attributes, individual farmer/rancher characteristics, relevant attitudes and knowledge significantly affect interest. Data from both methods allow us to highlight attributes of operators who are most likely to be early adopters of a woody biomass crop, can serve as an input to local or regional assessments of potential for renewable energy production, and have implications for the development of relevant policy initiatives and management practices.

  11. [Understory vegetation composition and main woody population niche of artificial masson pine forest in south subtropical area].

    PubMed

    Kang, Bing; Liu, Shirong; Shi, Zuomin; Wen, Yuanguang; Cai, Daoxiong; Lu, Lihua; Liang, Hongwen; Feng, Changlin

    2005-09-01

    This paper studied the characteristics of the natural understory vegetation in the artificial masson pine forest replanted after Chinese fir cut for 13 years. The results indicated that there were 100 species of understory vegetation, including 74 species of shrub or small arbor, accounting for 74.0% of the total species, belonging to 41 faculties and 63 categories, and 26 herbs belonging to 14 faculties and 23 categories. The tropical and subtropical elements were dominant in the vegetation, while the temperate ones were scare. The species diversity and richness were decreased after masson pine regenerated from Chinese fir. The analysis of important value showed that the main species of shrub or small arbor were Tinomiscium tonkinensis, Mycetia longiflora, Evodia lepta, Paederia scandens, Mussaenda pubuscens, Actinodaphne pilosa and Quercus glauca, and those of herb were Cyrtococcum patens, Blechnunm orientale, Dicranopteris dichotoma, Adiantum flabellulatum, Adiantum edgeworthii and Pteris semipinnata. The biomass of the vegetation in different slope positions was decreased in order of upside> downside > middle part. There was a significantly positive correlation between the niche breath and the important value of main woody population. The important values of woody populations were higher than those of the others, and their niche breadths were also larger, which meant that they were more adaptable to the habitat. The niche overlaps of six population counterparts Tinomiscium tonkinensis-Mycetia longiflora, Tinomiscium tonkinensis-Evodia lepta, Mussaenda pubuscens-Maesa japonica, Quercus glauca-Aphananthe aspera, Actinodaphne pilosa-Saraca chinensis and Evodia lepta-Quercus glaucathese were very large, which could offer information for the restoration and reconstruction in selecting natural vegetation. The large niche overlaps of major woody population counterparts suggested their similar utilization of natural resources.

  12. Simulation results of aboveground woody biomass and leaf litterfall for African tropical forest with a global terrestrial model

    NASA Astrophysics Data System (ADS)

    De Weirdt, Marjolein; Maignan, Fabienne; Peylin, Philippe; Poulter, Benjamin; Moreau, Inès; Ciais, Philippe; Defourny, Pierre; Steppe, Kathy; Verbeeck, Hans

    2014-05-01

    The response of tropical forest vegetation to global climate change could be central to predictions of future levels of atmospheric carbon dioxide. Tropical forests are believed to annually process approximately six times as much carbon via photosynthesis and respiration as humans emit from fossil fuel use. Of all tropical forests worldwide, the role of African tropical forest is not very well known and both the quantity as well as the dynamics of tropical forest carbon stocks and fluxes are very poorly quantified components of the global carbon cycle. Furthermore, African tropical forest spatial carbon stocks patterns as measured in the field are not as well represented by the global biogeochemical models as they are for temperate forests. In this study, a first simulation for the African tropical forest with the process based global terrestrial ecosystem model ORCHIDEE was done. In this work, ORCHIDEE included deep soils, seasonal leaf litterfall and phosphorus availability mechanisms for tropical evergreen forests included. The ORCHIDEE model run outputs are evaluated against reported field inventories, investigating seasonal variations in leaf litterfall and spatial variation in aboveground woody biomass. A comparison between modeled and measured leaf litterfall was made at a semi-deciduous Equatorial rainforest site in the Republic of Congo at the Biosphere reserve Dimonika south of Gabon. Also, simulated woody aboveground biomass was compared against site-level field inventories and satellite-based estimates based on a combination of MODIS imagery with field inventory data from Uganda, DRC and Cameroon. First comparison results seem promising and show that the radiation driven leaf litterfall model results correspond well with the field inventories and that the mean of the modelled aboveground woody biomass matches the available field inventory observations but there is still a need for more ground data to evaluate the model outcome over a large region like

  13. Woody plant phylogenetic diversity mediates bottom-up control of arthropod biomass in species-rich forests.

    PubMed

    Schuldt, Andreas; Baruffol, Martin; Bruelheide, Helge; Chen, Simon; Chi, Xiulian; Wall, Marcus; Assmann, Thorsten

    2014-09-01

    Global change is predicted to cause non-random species loss in plant communities, with consequences for ecosystem functioning. However, beyond the simple effects of plant species richness, little is known about how plant diversity and its loss influence higher trophic levels, which are crucial to the functioning of many species-rich ecosystems. We analyzed to what extent woody plant phylogenetic diversity and species richness contribute to explaining the biomass and abundance of herbivorous and predatory arthropods in a species-rich forest in subtropical China. The biomass and abundance of leaf-chewing herbivores, and the biomass dispersion of herbivores within plots, increased with woody plant phylogenetic diversity. Woody plant species richness had much weaker effects on arthropods, but interacted with plant phylogenetic diversity to negatively affect the ratio of predator to herbivore biomass. Overall, our results point to a strong bottom-up control of functionally important herbivores mediated particularly by plant phylogenetic diversity, but do not support the general expectation that top-down predator effects increase with plant diversity. The observed effects appear to be driven primarily by increasing resource diversity rather than diversity-dependent primary productivity, as the latter did not affect arthropods. The strong effects of plant phylogenetic diversity and the overall weaker effects of plant species richness show that the diversity-dependence of ecosystem processes and interactions across trophic levels can depend fundamentally on non-random species associations. This has important implications for the regulation of ecosystem functions via trophic interaction pathways and for the way species loss may impact these pathways in species-rich forests.

  14. Structural reinterpretation of Ruedi and Woody Creek quadrangles, Pitkin and Eagle Counties, Colorado: a central Colorado overthrust belt

    SciTech Connect

    Zoerner, F.P.

    1986-08-01

    The mountains northwest of Aspen, Colorado, are composed of Pennsylvanian through Triassic evaporites and molasse of the Eagle Valley, Belden, Minturn, Maroon, and State Bridge formations. Southwest of the Roaring Fork River and its tributary, Woody Creek, are Jurassic through Cretaceous sediments that unconformably overlie these older rocks. This entire sequence is located in the Elk Range thrust sheet. Along Woody Creek and the Roaring Fork River, Bryant and Freeman have mapped the continuation of the Castle Creek fault zone. These writers interpreted the fault zone as a southeast-dipping normal fault with a horst of Eagle Valley formation continuously present between the Pennsylvanian-Triassic and Cretaceous beds within the fault zone. Southwestward thrusting on a decollement within the Eagle Valley evaporite sequence would explain (1) its presence in the fault zone, (2) the 17,000 + ft of stratigraphic throw, and (3) the structural discordance across the fault zone. The author interprets the fault zone to be a northeast-dipping gravity slide that has been thrust off and possibly pushed by the Laramide Sawatch uplift. Cross sections through the area have similar geometry to those for the Elk Range and Hunters Hill thrusts to the south-southwest. The upturned heel is exposed along the Sawatch structural front between Hunter Creek (north of Aspen) and Lenado. These relationships suggest that another thrust paralleling the Fryingpan River is possible to the north. The author proposes the name Roaring fork thrust for the fault zone in the Woody Creek and Roaring Fork River valleys. The Castle Creek fault zone should be reserved for the fault zone in the drainage south of Aspen and the southwest projection of the Homestake shear zone, against which is appears to terminate.

  15. [Transmission of Passion fruit woodiness virus by Aphis gossypii (Glover) (Hemiptera: Aphididae) and colonization of passion flower by the vector].

    PubMed

    Di Piero, Robson M; Rezende, Jorge A M; Yuki, Valdir A; Pascholati, Sérgio F; Delfino, Miguel Angel

    2006-01-01

    The transmission of Passion fruit woodiness virus (PWV) by Aphis gossypii (Glover) was evaluated. In two independent experiments, A. gossypii transmitted PWV to passion fruit plants at the rates of 75% and 100%, when eight and twelve viruliferous aphids were deposited by plant, respectively. At the end of the tests, nymphs of A. gossypii were observed in some of the passion fruit plants, suggesting that the aphid species was colonizing the plants. This seems to be the first report of Passiflora edulis f. flavicarpa (Deneger) colonization by a species of aphid.

  16. On the potential of long wavelength imaging radars for mapping vegetation types and woody biomass in tropical rain forests

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Zimmermann, Reiner; Oren, Ram

    1995-01-01

    In the tropical rain forests of Manu, in Peru, where forest biomass ranges from 4 kg/sq m in young forest succession up to 100 kg/sq m in old, undisturbed floodplain stands, the P-band polarimetric radar data gathered in June of 1993 by the AIRSAR (Airborne Synthetic Aperture Radar) instrument separate most major vegetation formations and also perform better than expected in estimating woody biomass. The worldwide need for large scale, updated biomass estimates, achieved with a uniformly applied method, as well as reliable maps of land cover, justifies a more in-depth exploration of long wavelength imaging radar applications for tropical forests inventories.

  17. Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species.

    PubMed

    Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo; Meinzer, Frederick C; Arce, Maria E

    2009-07-01

    Adaptations of species to capture limiting resources is central for understanding structure and function of ecosystems. We studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and potentials, leaf water potentials (Psi(Leaf)), hydraulic conductivity, wood density (rho(w)), rooting depth, and specific leaf area (SLA) were measured during two summers. Water potentials in the upper soil layers during a summer drought ranged from -2.3 to -3.6 MPa, increasing to -0.05 MPa below 150 cm. Predawn Psi(Leaf) was used as a surrogate of weighted mean soil water potential because no statistical differences in Psi(Leaf) were observed between exposed and covered leaves. Species-specific differences in predawn Psi(Leaf) were consistent with rooting depths. Predawn Psi(Leaf) ranged from -4.0 MPa for shallow rooted shrubs to -1.0 MPa for deep-rooted shrubs, suggesting that the roots of the latter have access to abundant moisture, whereas shallow-rooted shrubs are adapted to use water deposited mainly by small rainfall events. Wood density was a good predictor of hydraulic conductivity and SLA. Overall, we found that shallow rooted species had efficient water transport in terms of high specific and leaf specific hydraulic conductivity, low rho(w), high SLA and a low minimum Psi(Leaf) that exhibited strong seasonal changes, whereas deeply rooted shrubs maintained similar minimum Psi(Leaf) throughout the year, had stems with high rho(w) and low hydraulic conductivity and leaves with low SLA. These two hydraulic syndromes were the extremes of a continuum with several species occupying different portions of a gradient in hydraulic characteristics. It appears that the marginal cost of having an extensive root system (e.g., high rho(w) and root hydraulic resistance) contributes to low growth rates

  18. Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

    NASA Astrophysics Data System (ADS)

    Máguas, C.; Rascher, K. G.; Martins-Loução, A.; Carvalho, P.; Pinho, P.; Ramos, M.; Correia, O.; Werner, C.

    2011-12-01

    In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW) availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels) in a sand dune ecosystem. For that, five sites were established within a 1 km2 area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader) and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy). Species comparison revealed that variability in pre-dawn water potential (Ψpre) and bulk leaf δ13C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya) and phreatophyte (Salix repens) species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic exploitation, in plant species from sand dunes, is variable, being particularly relevant for deep

  19. On the measure of large woody debris in an alpine catchment

    NASA Astrophysics Data System (ADS)

    D'Agostino, V.; Bertoldi, G.; Rigon, E.

    2012-04-01

    The management of large woody debris (LWD) in Alpine torrents is a complex and ambiguous task. On one side the presence of LWD contributes to in-channel and floodplain morphological processes and plays an important role in landscape ecology and biodiversity. On the other side LWD increases considerably flood hazards when some river cross-sections result critical for the human interface (e.g. culverts, bridges, artificial channels). Only few studies provide quantitative data of LWD volumes in Alpine torrents. Research is needed both at basin scale processes (LWD recruiting from hillslopes) and at channel scale processes (feeding from river bank, storage/transport/deposition of LWD along the river bed). Our study proposes an integrate field survey methodology to assess the overall LWD amount which can be entrained by a flood. This knowledge is mandatory for the scientific research, for the implementation of LWD transport models, and for a complete hazard management in mountain basins. The study site is the high-relief basin of the Cordevole torrent (Belluno Province, Central Alps, Italy) whose outlet is located at the Saviner village (basin area of 109 square kilometers). In the November 1966 an extreme flood event occurred and some torrent reaches were heavily congested by LWD enhancing the overall damages due to long-duration overflows. Currently, the LWD recruitment seems to be strictly correlated with bank erosion and hillslope instability and the conditions of forest stand suggest LWD hazard is still high. Previous studies on sub-catchments of the Cordevole torrent have also shown an inverse relation between the drainage area and the LWD storage in the river-bed. Present contribution analyzes and quantifies the presence of LWD in the main valley channel of the Cordevole basin. A new sampling methodology was applied to integrate surveys of riparian vegetation and LWD storage. Data inventory confirms the previous relationship between LWD volumes and drainage area

  20. Woody debris contribution to the carbon budget of selectively logged and maturing mid-latitude forests.

    PubMed

    Liu, Wendy H; Bryant, David M; Hutyra, Lucy R; Saleska, Scott R; Hammond-Pyle, Elizabeth; Curran, Daniel; Wofsy, Steven C

    2006-05-01

    Woody debris (WD) is an important component of forest C budgets, both as a C reservoir and source of CO2 to the atmosphere. We used an infrared gas analyzer and closed dynamic chamber to measure CO(2) efflux from downed coarse WD (CWD; diameter>or=7.5 cm) and fine WD (FWD; 7.5 cm>diameter>or=2 cm) to assess respiration in a selectively logged forest and a maturing forest (control site) in the northeastern USA. We developed two linear regression models to predict WD respiration: one based on WD temperature, moisture, and size (R2=0.57), and the other on decay class and air temperature (R2=0.32). WD respiration (0.28+/-0.09 Mg C ha-1 year-1) contributed only approximately 2% of total ecosystem respiration (12.3+/-0.7 Mg C ha-1 year-1, 1999-2003), but net C flux from CWD accounted for up to 30% of net ecosystem exchange in the maturing forest. C flux from CWD on the logged site increased modestly, from 0.61+/-0.29 Mg C ha-1 year-1 prior to logging to 0.77+/-0.23 Mg C ha-1 year-1 after logging, reflecting increased CWD stocks. FWD biomass and associated respiration flux were approximately 7 times and approximately 5 times greater, respectively, in the logged site than the control site. The net C flux associated with CWD, including inputs and respiratory outputs, was 0.35+/-0.19 Mg C ha-1 year-1 (net C sink) in the control site and -0.30+/-0.30 Mg C ha-1 year-1 (net C source) in the logged site. We infer that accumulation of WD may represent a small net C sink in maturing northern hardwood forests. Disturbance, such as selective logging, can enlarge the WD pool, increasing the net C flux from the WD pool to the atmosphere and potentially causing it to become a net C source.

  1. Mapping invasive species and spectral mixture relationships with neotropical woody formations in southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Amaral, Cibele H.; Roberts, Dar A.; Almeida, Teodoro I. R.; Souza Filho, Carlos R.

    2015-10-01

    Biological invasion substantially contributes to the increasing extinction rates of native vegetative species. The remote detection and mapping of invasive species is critical for environmental monitoring. This study aims to assess the performance of a Multiple Endmember Spectral Mixture Analysis (MESMA) applied to imaging spectroscopy data for mapping Dendrocalamus sp. (bamboo) and Pinus elliottii L. (slash pine), which are invasive plant species, in a Brazilian neotropical landscape within the tropical Brazilian savanna biome. The work also investigates the spectral mixture between these exotic species and the native woody formations, including woodland savanna, submontane and alluvial seasonal semideciduous forests (SSF). Visible to Shortwave Infrared (VSWIR) imaging spectroscopy data at one-meter spatial resolution were atmospherically corrected and subset into the different spectral ranges (VIS-NIR1: 530-919 nm; and NIR2-SWIR: 1141-2352 nm). The data were further normalized via continuum removal (CR). Multiple endmember selection methods, including Interactive Endmember Selection (IES), Endmember average root mean square error (EAR), Minimum average spectral angle (MASA) and Count-based (CoB) (collectively called EMC), were employed to create endmember libraries for the targeted vegetation classes. The performance of the MESMA was assessed at the pixel and crown scales. Statistically significant differences (α = 0.05) were observed between overall accuracies that were obtained at various spectral ranges. The infrared region (IR) was critical for detecting the vegetation classes using spectral data. The invasive species endmembers exhibited spectral patterns in the IR that were not observed in the native formations. Bamboo was characterized as having a high green vegetation (GV) fraction, lower non-photosynthetic vegetation (NPV) and a low shade fraction, while pine exhibited higher NPV and shade fractions. The invasive species showed a statistically

  2. Hydraulic and Geomorphic Effects of Large Woody Debris Additions in the Narraguagus Watershed, Coastal Maine

    NASA Astrophysics Data System (ADS)

    Johnson, E.; Snyder, N. P.

    2009-12-01

    Maine coastal rivers host the last remaining runs of endangered anadromous Atlantic salmon in the United States, whose populations have declined from ~500,000 returning adults in the 1880s to only ~1000 in 2000. Restoration projects focus on these rivers, and recent efforts involve adding large woody debris (LWD) to small tributaries to improve salmon rearing habitat. LWD changes the hydraulics and geomorphology of small streams by acting as a barrier to flow and resulting in decreased velocity zones, scour pools, and sediment storage and sorting. We quantify the effects of LWD additions in early August 2008 on hydraulics and substrate in Baker Brook, a west-flowing tributary of the Narraguagus River. Hydraulically, we focus on the treatment reach nearest the confluence with the Narraguagus River (Baker1). We study substrate in this and the upstream treatment location (Baker3). Both study locations are divided into two reaches, treatment (received cut wood) and control (did not receive cut wood). The reaches are further divided into 50 m sub-reaches based on gradient (1-2%). We seek to answer two research questions: (1) how much does mean velocity through the study sub-reaches change as a result of additions; and (2) does sediment storage and sorting result from the LWD additions? We measured reach-average velocities (Ureach) in Baker1 using the salt dilution method in May, July, August and October 2008 and May 2009. We use rating curves to compare the post-treatment to the pre-treatment Ureach-stage relationship. No reach-average change was quantified during the low-to-moderate flows we observed. We found a localized change in cross-sectionally averaged velocity (U⊥) measured with a flow meter in one sub-reach, but this is because an added tree intersected the cross-section where measurements were recorded. We quantified pre- and post-treatment sub-reach substrate median grain size (D50) with intensive clast counts in July 2008 and May 2009. Two of the three

  3. Disentangling the drivers of coarse woody debris behavior and carbon gas emissions during fire

    NASA Astrophysics Data System (ADS)

    Zhao, Weiwei; van der Werf, Guido R.; van Logtestijn, Richard S. P.; van Hal, Jurgen R.; Cornelissen, Johannes H. C.

    2016-04-01

    The turnover of coarse woody debris, a key terrestrial carbon pool, plays fundamental roles in global carbon cycling. Biological decomposition and fire are two main fates for dead wood turnover. Compared to slow decomposition, fire rapidly transfers organic carbon from the earth surface to the atmosphere. Both a-biotic environmental factors and biotic wood properties determine coarse wood combustion and thereby its carbon gas emissions during fire. Moisture is a key inhibitory environmental factor for fire. The properties of dead wood strongly affect how it burns either directly or indirectly through interacting with moisture. Coarse wood properties vary between plant species and between various decay stages. Moreover, if we put a piece of dead wood in the context of a forest fuel bed, the soil and wood contact might also greatly affect their fire behavior. Using controlled laboratory burns, we disentangled the effects of all these driving factors: tree species (one gymnosperms needle-leaf species, three angiosperms broad-leaf species), wood decay stages (freshly dead, middle decayed, very strongly decayed), moisture content (air-dried, 30% moisture content in mass), and soil-wood contact (on versus 3cm above the ground surface) on dead wood flammability and carbon gas efflux (CO2 and CO released in grams) during fire. Wood density was measured for all coarse wood samples used in our experiment. We found that compared to other drivers, wood decay stages have predominant positive effects on coarse wood combustion (for wood mass burned, R2=0.72 when air-dried and R2=0.52 at 30% moisture content) and associated carbon gas emissions (for CO2andCO (g) released, R2=0.55 when air-dried and R2=0.42 at 30% moisture content) during fire. Thus, wood decay accelerates wood combustion and its CO2 and CO emissions during fire, which can be mainly attributed to the decreasing wood density (for wood mass burned, R2=0.91 when air-dried and R2=0.63 at 30% moisture content) as wood

  4. Effect of woody and herbaceous plants on chemical weathering of basalt material

    NASA Astrophysics Data System (ADS)

    Mark, N.; Dontsova, K.; Barron-Gafford, G. A.

    2011-12-01

    Worldwide, semi-arid landscapes are transitioning from shallow-rooted grasslands to mixed vegetation savannas composed of deeper-rooted shrubs. These contrasting growth forms differentially drive below-ground processes because they occupy different soil horizons, are differentially stressed by periods of drought, and unequally stimulate soil weathering. Our study aims to determine the effect of woody and herbaceous plants on weathering of granular basalt serving as a model for soil. We established pots with velvet mesquite (Prosopis veluntina), sideoats grama (Bouteloua curtipendula), and bare-soil pots within two temperature treatments in University of Arizona Biosphere 2. The Desert biome served as the ambient temperature treatment, while the Savanna biome was maintained 4°C warmer to simulate projected air temperatures if climate change continues unabated. Rhizon water samplers were installed at a depth of one inch from the soil surface to monitor root zone exudates (total dissolved carbon and nitrogen), dissolved inorganic carbon, and lithogenic elements resulting from basalt weathering. Soil leachates were collected through the course of the experiment. The anion content of the leachates was determined using the ICS-5000 Reagent-Free ion chromatography system. Dissolved carbon and nitrogen were analyzed by combustion using the Shimadzu TOC-VCSH with TN module. Metals and metalloids were measured using inductively coupled plasma mass spectrometry. Irrigation of the pots was varied in time to simulate periods of drought and determine the effect of stress on root exudation. Leachates from all treatments displayed higher pH and electrical conductivity than water used for irrigation indicating weathering. On average, leachates from the potted grasses displayed higher pH and electrical conductivity than mesquites. This agreed with higher concentrations of organic carbon, a measure of root exudation, and inorganic carbon, measure of soil respiration. Both organic

  5. Relationships of the Woody Medicago Species (Section Dendrotelis) Assessed by Molecular Cytogenetic Analyses

    PubMed Central

    Rosato, Marcela; Castro, Mercedes; Rosselló, Josep A.

    2008-01-01

    Background and Aims The organization of rDNA genes in the woody medic species from the agronomically important Medicago section Dendrotelis was analysed to gain insight into their taxonomic relationships, to assess the levels of infraspecific variation concerning ribosomal loci in a restricted and fragmented insular species (M. citrina) and to assess the nature of its polyploidy. Methods Fluorescence in situ hybridization (FISH) was used for physical mapping of 5S and 45S ribosomal DNA genes in the three species of section Dendrotelis (M. arborea, M. citrina, M. strasseri) and the related M. marina from section Medicago. Genomic in situ hybridization (GISH) was used to assess the genomic relationships of the polyploid M. citrina with the putatively related species from section Dendrotelis. Key Results The diploid (2n = 16) M. marina has a single 45S and two 5S rDNA loci, a pattern usually detected in previous studies of Medicago diploid species. However, polyploid species from section Dendrotelis depart from expectations. The tetraploid species (2n = 32) M. arborea and M. strasseri have one 45S rDNA locus and two 5S rDNA loci, whereas in the hexaploid (2n = 48) M. citrina four 45S rDNA and five 5S rDNA loci have been detected. No single chromosome of M. citrina was uniformly labelled after using genomic probes from M. arborea and M. strasseri. Instead, cross-hybridization signals in M. citrina were restricted to terminal chromosome arms and NOR regions. Conclusions FISH results support the close taxonomic interrelationship between M. arborea and M. strasseri. In these tetraploid species, NOR loci have experienced a diploidization event through physical loss of sequences, a cytogenetic feature so far not reported in other species of the genus. The high number of rDNA loci and GISH results support the specific status for the hexaploid M. citrina, and it is suggested that this species is not an autopolyploid derivative of M. arborea or M. strasseri. Further, molecular

  6. Woody plant richness and NDVI response to drought events in Catalonian (northeastern Spain) forests.

    PubMed

    Lloret, F; Lobo, A; Estevan, H; Maisongrande, P; Vayreda, J; Terradas, J

    2007-09-01

    The role of species diversity on ecosystem resistance in the face of strong environmental fluctuations has been addressed from both theoretical and experimental viewpoints to reveal a variety of positive and negative relationships. Here we explore empirically the relationship between the richness of forest woody species and canopy resistance to extreme drought episodes. We compare richness data from an extensive forest inventory to a temporal series of satellite imagery that estimated drought impact on forest canopy as NDVI (normalized difference vegetation index) anomalies of the dry summer in 2003 in relation to records of previous years. We considered five different types of forests that are representative of the main climatic and altitudinal gradients of the region, ranging from lowland Mediterranean to mountain boreal-temperate climates. The observed relationship differed among forest types and interacted with the climate, summarised by the Thorntwaite index. In Mediterranean Pinus halepensis forests, NDVI decreased during the drought. This decrease was stronger in forests with lower richness. In Mediterranean evergreen forests of Quercus ilex, drought did not result in an overall NDVI loss, but lower NDVI values were observed in drier localities with lower richness, and in more moist localities with higher number of species. In mountain Pinus sylvestris forests NDVI decreased, mostly due to the drought impact on drier localities, while no relation to species richness was observed. In moist Fagus sylvatica forests, NDVI only decreased in plots with high richness. No effect of drought was observed in the high mountain Pinus uncinata forests. Our results show that a shift on the diversity-stability relationship appears across the regional, climatic gradient. A positive relationship appears in drier localities, supporting a null model where the probability of finding a species able to cope with drier conditions increases with the number of species. However, in

  7. A "clearcut" case? Brown bear selection of coarse woody debris and carpenter ants on clearcuts.

    PubMed

    Frank, Shane C; Steyaert, Sam M J G; Swenson, Jon E; Storch, Ilse; Kindberg, Jonas; Barck, Hanna; Zedrosser, Andreas

    2015-07-15

    Forest management alters habitat characteristics, resulting in various effects among and within species. It is crucial to understand how habitat alteration through forest management (e.g. clearcutting) affects animal populations, particularly with unknown future conditions (e.g. climate change). In Sweden, brown bears (Ursus arctos) forage on carpenter ants (Camponotus herculeanus) during summer, and may select for this food source within clearcuts. To assess carpenter ant occurrence and brown bear selection of carpenter ants, we sampled 6999 coarse woody debris (CWD) items within 1019 plots, of which 902 were within clearcuts (forests ⩽30 years of age) and 117 plots outside clearcuts (forests >30 years of age). We related various CWD and site characteristics to the presence or absence of carpenter ant galleries (nests) and bear foraging sign at three spatial scales: the CWD, plot, and clearcut scale. We tested whether both absolute and relative counts (the latter controlling for the number of CWD items) of galleries and bear sign in plots were higher inside or outside clearcuts. Absolute counts were higher inside than outside clearcuts for galleries (mean counts; inside: 1.8, outside: 0.8). CWD was also higher inside (mean: 6.8) than outside clearcuts (mean: 4.0). However, even after controlling for more CWD inside clearcuts, relative counts were higher inside than outside clearcuts for both galleries (mean counts; inside: 0.3, outside: 0.2) and bear sign (mean counts; inside: 0.03, outside: 0.01). Variables at the CWD scale best explained gallery and bear sign presence than variables at the plot or clearcut level, but bear selection was influenced by clearcut age. CWD circumference was important for both carpenter ant and bear sign presence. CWD hardness was most important for carpenter ant selection. However, the most important predictor for bear sign was the presence or absence of carpenter ant galleries. Bears had a high foraging "success" rate (