Science.gov

Sample records for leaf nutrient ranges

  1. Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency

    PubMed Central

    Maillard, Anne; Diquélou, Sylvain; Billard, Vincent; Laîné, Philippe; Garnica, Maria; Prudent, Marion; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2015-01-01

    Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K–P–S–Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu–Mo–Ni–B–Fe–Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N–S–Cu) or increased by nutrient deficiency (K–P–Mg) while nutrient deficiency had no effect on Mo–Zn–B–Ca–Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms. PMID:26029223

  2. Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency.

    PubMed

    Maillard, Anne; Diquélou, Sylvain; Billard, Vincent; Laîné, Philippe; Garnica, Maria; Prudent, Marion; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2015-01-01

    Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K-P-S-Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu-Mo-Ni-B-Fe-Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N-S-Cu) or increased by nutrient deficiency (K-P-Mg) while nutrient deficiency had no effect on Mo-Zn-B-Ca-Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms. PMID:26029223

  3. Weak leaf photosynthesis and nutrient content relationships from tropical vegetation

    NASA Astrophysics Data System (ADS)

    Domingues, T. F.; Ishida, F. Y.; Feldpaush, T.; Saiz, G.; Grace, J.; Meir, P.; Lloyd, J.

    2015-12-01

    Evergreen rain forests and savannas are the two major vegetations of tropical land ecosystems, in terms of land area, biomass, biodiversity, biogeochemical cycles and rates of land use change. Mechanistically understanding ecosystem functioning on such ecosystems is still far from complete, but important for generation of future vegetation scenarios in response to global changes. Leaf photosynthetic rates is a key processes usually represented on land surface-atmosphere models, although data from tropical ecosystems is scarce, considering the high biodiversity they contain. As a shortcut, models usually recur to relationships between leaf nutrient concentration and photosynthetic rates. Such strategy is convenient, given the possibility of global datasets on leave nutrients derived from hyperspectral remote sensing data. Given the importance of Nitrogen on enzyme composition, this nutrient is usually used to infer photosynthetic capacity of leaves. Our experience, based on individual measurements on 1809 individual leaves from 428 species of trees and shrubs naturally occurring on tropical forests and savannas from South America, Africa and Australia, indicates that the relationship between leaf nitrogen and its assimilation capacity is weak. Therefore, leaf Nitrogen alone is a poor predictor of photosynthetic rates of tropical vegetation. Phosphorus concentrations from tropical soils are usually low and is often implied that this nutrient limits primary productivity of tropical vegetation. Still, phosphorus (or other nutrients) did not exerted large influence over photosynthetic capacity, although potassium influenced vegetation structure and function. Such results draw attention to the risks of applying universal nitrogen-photosynthesis relationships on biogeochemical models. Moreover, our data suggests that affiliation of plant species within phylogenetic hierarchy is an important aspect in understanding leaf trait variation. The lack of a strong single

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

    USGS Publications Warehouse

    Stohlgren, Thomas J.

    1988-01-01

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

  5. The effects of leaf litter nutrient pulses on Alliaria petiolata performance.

    PubMed

    Heckman, Robert W; Carr, David E

    2015-01-01

    Nutrient pulses can facilitate species establishment and spread in new habitats, particularly when one species more effectively uses that nutrient pulse. Biological differences in nutrient acquisition between native and exotic species may facilitate invasions into a variety of habitats including deciduous forest understories. Alliaria petiolata (Bieb.) Cavara & Grande is an important invader of deciduous forest understories throughout much of North America. These understory communities contain many species which perform the majority of their growth and reproduction before canopy closure in spring. Because A. petiolata is a wintergreen biennial that can be active during autumn and winter, it may utilize nutrients released from decaying leaf litter before its competitors. To investigate this we manipulated the timing of leaf litter addition (fall or spring) and experimentally simulated the nutrient pulse from decaying leaves using artificial fertilizer. To determine whether A. petiolata affected the abundance of understory competitors, we also removed A. petiolata from one treatment. A. petiolata that received early nutrients exhibited greater growth. Treatments receiving fall leaf litter or artificial nutrients had greater A. petiolata adult biomass than plots receiving spring nutrient additions (leaf litter or artificial nutrients). However, fall leaf litter addition had no effect on the richness of competitor species. Thus, wintergreen phenology may contribute to the spread of A. petiolata through deciduous forest understories, but may not explain community-level impacts of A. petiolata in deciduous forests. PMID:26312176

  6. The effects of leaf litter nutrient pulses on Alliaria petiolata performance.

    PubMed

    Heckman, Robert W; Carr, David E

    2015-01-01

    Nutrient pulses can facilitate species establishment and spread in new habitats, particularly when one species more effectively uses that nutrient pulse. Biological differences in nutrient acquisition between native and exotic species may facilitate invasions into a variety of habitats including deciduous forest understories. Alliaria petiolata (Bieb.) Cavara & Grande is an important invader of deciduous forest understories throughout much of North America. These understory communities contain many species which perform the majority of their growth and reproduction before canopy closure in spring. Because A. petiolata is a wintergreen biennial that can be active during autumn and winter, it may utilize nutrients released from decaying leaf litter before its competitors. To investigate this we manipulated the timing of leaf litter addition (fall or spring) and experimentally simulated the nutrient pulse from decaying leaves using artificial fertilizer. To determine whether A. petiolata affected the abundance of understory competitors, we also removed A. petiolata from one treatment. A. petiolata that received early nutrients exhibited greater growth. Treatments receiving fall leaf litter or artificial nutrients had greater A. petiolata adult biomass than plots receiving spring nutrient additions (leaf litter or artificial nutrients). However, fall leaf litter addition had no effect on the richness of competitor species. Thus, wintergreen phenology may contribute to the spread of A. petiolata through deciduous forest understories, but may not explain community-level impacts of A. petiolata in deciduous forests.

  7. The effects of leaf litter nutrient pulses on Alliaria petiolata performance

    PubMed Central

    Carr, David E.

    2015-01-01

    Nutrient pulses can facilitate species establishment and spread in new habitats, particularly when one species more effectively uses that nutrient pulse. Biological differences in nutrient acquisition between native and exotic species may facilitate invasions into a variety of habitats including deciduous forest understories. Alliaria petiolata (Bieb.) Cavara & Grande is an important invader of deciduous forest understories throughout much of North America. These understory communities contain many species which perform the majority of their growth and reproduction before canopy closure in spring. Because A. petiolata is a wintergreen biennial that can be active during autumn and winter, it may utilize nutrients released from decaying leaf litter before its competitors. To investigate this we manipulated the timing of leaf litter addition (fall or spring) and experimentally simulated the nutrient pulse from decaying leaves using artificial fertilizer. To determine whether A. petiolata affected the abundance of understory competitors, we also removed A. petiolata from one treatment. A. petiolata that received early nutrients exhibited greater growth. Treatments receiving fall leaf litter or artificial nutrients had greater A. petiolata adult biomass than plots receiving spring nutrient additions (leaf litter or artificial nutrients). However, fall leaf litter addition had no effect on the richness of competitor species. Thus, wintergreen phenology may contribute to the spread of A. petiolata through deciduous forest understories, but may not explain community-level impacts of A. petiolata in deciduous forests. PMID:26312176

  8. Short-Term Effect of Nutrient Availability and Rainfall Distribution on Biomass Production and Leaf Nutrient Content of Savanna Tree Species

    PubMed Central

    Barbosa, Eduardo R. M.; Tomlinson, Kyle W.; Carvalheiro, Luísa G.; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H. T.; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings’ above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient

  9. Short-term effect of nutrient availability and rainfall distribution on biomass production and leaf nutrient content of savanna tree species.

    PubMed

    Barbosa, Eduardo R M; Tomlinson, Kyle W; Carvalheiro, Luísa G; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H T; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings' above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient concentration

  10. Nutrients stimulate leaf breakdown rates and detritivore biomass: Bottom-up effects via heterotrophic pathways

    USGS Publications Warehouse

    Greenwood, J.L.; Rosemond, A.D.; Wallace, J.B.; Cross, W.F.; Weyers, H.S.

    2007-01-01

    Most nutrient enrichment studies in aquatic systems have focused on autotrophic food webs in systems where primary producers dominate the resource base. We tested the heterotrophic response to long-term nutrient enrichment in a forested, headwater stream. Our study design consisted of 2 years of pretreatment data in a reference and treatment stream and 2 years of continuous nitrogen (N) + phosphorus addition to the treatment stream. Studies were conducted with two leaf species that differed in initial C:N, Rhododendron maximum (rhododendron) and Acer rubrum (red maple). We determined the effects of nutrient addition on detrital resources (leaf breakdown rates, litter C:N and microbial activity) and tested whether nutrient enrichment affected macroinvertebrate consumers via increased biomass. Leaf breakdown rates were ca. 1.5 and 3?? faster during the first and second years of enrichment, respectively, in the treatment stream for both leaf types. Microbial respiration rates of both leaf types were 3?? higher with enrichment, and macroinvertebrate biomass associated with leaves increased ca. 2-3?? with enrichment. The mass of N in macroinvertebrate biomass relative to leaves tended to increase with enrichment up to 6?? for red maple and up to 44?? for rhododendron leaves. Lower quality (higher C:N) rhododendron leaves exhibited greater changes in leaf nutrient content and macroinvertebrate response to nutrient enrichment than red maple leaves, suggesting a unique response by different leaf species to nutrient enrichment. Nutrient concentrations used in this study were moderate and equivalent to those in streams draining watersheds with altered land use. Thus, our results suggest that similarly moderate levels of enrichment may affect detrital resource quality and subsequently lead to altered energy and nutrient flow in detrital food webs. ?? 2006 Springer-Verlag.

  11. Evaluation of leaf removal as a means to reduce nutrient concentrations and loads in urban stormwater.

    PubMed

    Selbig, William R

    2016-11-15

    While the sources of nutrients to urban stormwater are many, the primary contributor is often organic detritus, especially in areas with dense overhead tree canopy. One way to remove organic detritus before it becomes entrained in runoff is to implement a city-wide leaf collection and street cleaning program. Improving our knowledge of the potential reduction of nutrients to stormwater through removal of leaves and other organic detritus on streets could help tailor more targeted municipal leaf collection programs. This study characterized an upper ideal limit in reductions of total and dissolved forms of phosphorus and nitrogen in stormwater through implementation of a municipal leaf collection and street cleaning program in Madison, WI, USA. Additional measures were taken to remove leaf litter from street surfaces prior to precipitation events. Loads of total and dissolved phosphorus were reduced by 84 and 83% (p<0.05), and total and dissolved nitrogen by 74 and 71% (p<0.05) with an active leaf removal program. Without leaf removal, 56% of the annual total phosphorus yield (winter excluded) was due to leaf litter in the fall compared to 16% with leaf removal. Despite significant reductions in load, total nitrogen showed only minor changes in fall yields without and with leaf removal at 19 and 16%, respectively. The majority of nutrient concentrations were in the dissolved fraction making source control through leaf removal one of the few treatment options available to environmental managers when reducing the amount of dissolved nutrients in stormwater runoff. Subsequently, the efficiency, frequency, and timing of leaf removal and street cleaning are the primary factors to consider when developing a leaf management program.

  12. Evaluation of leaf removal as a means to reduce nutrient concentrations and loads in urban stormwater.

    PubMed

    Selbig, William R

    2016-11-15

    While the sources of nutrients to urban stormwater are many, the primary contributor is often organic detritus, especially in areas with dense overhead tree canopy. One way to remove organic detritus before it becomes entrained in runoff is to implement a city-wide leaf collection and street cleaning program. Improving our knowledge of the potential reduction of nutrients to stormwater through removal of leaves and other organic detritus on streets could help tailor more targeted municipal leaf collection programs. This study characterized an upper ideal limit in reductions of total and dissolved forms of phosphorus and nitrogen in stormwater through implementation of a municipal leaf collection and street cleaning program in Madison, WI, USA. Additional measures were taken to remove leaf litter from street surfaces prior to precipitation events. Loads of total and dissolved phosphorus were reduced by 84 and 83% (p<0.05), and total and dissolved nitrogen by 74 and 71% (p<0.05) with an active leaf removal program. Without leaf removal, 56% of the annual total phosphorus yield (winter excluded) was due to leaf litter in the fall compared to 16% with leaf removal. Despite significant reductions in load, total nitrogen showed only minor changes in fall yields without and with leaf removal at 19 and 16%, respectively. The majority of nutrient concentrations were in the dissolved fraction making source control through leaf removal one of the few treatment options available to environmental managers when reducing the amount of dissolved nutrients in stormwater runoff. Subsequently, the efficiency, frequency, and timing of leaf removal and street cleaning are the primary factors to consider when developing a leaf management program. PMID:27470671

  13. Linking spatial patterns of leaf litterfall and soil nutrients in a tropical forest: a neighborhood approach.

    PubMed

    Uriarte, María; Turner, Benjamin L; Thompson, Jill; Zimmerman, Jess K

    2015-10-01

    Leaf litter represents an important link between tree community composition, forest productivity and biomass, and ecosystem processes. In forests, the spatial distribution of trees and species-specific differences in leaf litter production and quality are likely to cause spatial heterogeneity in nutrient returns to the forest floor and, therefore, in the redistribution of soil nutrients. Using mapped trees and leaf litter data for 12 tree species in a subtropical forest with a well-documented history of land use, we: (1) parameterized spatially explicit models of leaf litter biomass and nutrient deposition; (2) assessed variation in leaf litter inputs across forest areas with different land use legacies; and (3) determined the degree to which the quantity and quality of leaf litter inputs and soil physical characteristics are associated with spatial heterogeneity in soil nutrient ratios (C:N and N:P). The models captured the effects of tree size and location on spatial variation in leaf litterfall (R² = 0.31-0.79). For all 12 focal species, most of the leaf litter fell less than 5 m away from the source trees, generating fine- scale spatial heterogeneity in leaf litter inputs. Secondary forest species, which dominate areas in earlier successional stages, had lower leaf litter C:N ratios and produced less litter biomass than old-growth specialists. In contrast, P content and N:P ratios did not vary consistently among successional groups. Interspecific variation in leaf litter quality translated into differences in the quantity and quality (C:N) of total leaf litter biomass inputs and among areas with different land use histories. Spatial variation in leaf litter C:N inputs was the major factor associated with heterogeneity in soil C:N ratios relative to soil physical characteristics. In contrast, spatial variation soil N:P was more strongly associated with spatial variation in topography than heterogeneity in leaf litter inputs. The modeling approach presented here

  14. Species differences in timing of leaf fall and foliage chemistry modify nutrient resorption efficiency in deciduous temperate forest stands.

    PubMed

    Niinemets, Ulo; Tamm, Ulo

    2005-08-01

    Extensive variation in fractional resorption of mineral elements from plant leaves is still not fully understood. In multi-species forest stands, species leaf fall phenology and leaf constitution may significantly modify the timing of nutrient return to the soil and overall plant nutrient loss. We studied leaf fall and nutrient loss kinetics, and leaf composition in three natural, temperate, deciduous broadleaf forest stands to determine the role of timing of leaf abscission and nutrient immobilization in cell walls on nutrient resorption efficiency of senescing leaves. Nitrogen (N), phosphorus and potassium contents decreased continuously in attached leaves after peak physiological activity during mid-season. Changes in nutrient contents of attached leaves were paralleled by decreases in nutrient contents in freshly fallen leaf litter. In different species and for different nutrients, resorption of nutrients from senescing leaves proceeded with different kinetics. The maximum nutrient resorption efficiency (the fraction of specific nutrient resorbed from the leaves at the end of leaf fall) did not depend on the mid-seasonal nutrient concentration. Species with earlier leaf fall resorbed leaf nutrients at a faster rate, partly compensating for the earlier leaf fall. Nevertheless, the litter-mass weighted mean nutrient contents in leaf litter were still larger in species with earlier leaf fall, demonstrating an inherent trade-off between early leaf fall and efficient nutrient resorption. This trade-off was most important for N. Losses of the non-mobile nutrients calcium and magnesium were unaffected by the timing of leaf fall. There was large variation in the maximum N resorption efficiency among species. Correlations among leaf chemical variables suggested that the maximum N resorption efficiency decreased with the increasing fraction of cell walls in the leaves, possibly due to a greater fraction of N occluded in cell wall matrix. We conclude that species leaf

  15. Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency.

    PubMed

    Estiarte, Marc; Peñuelas, Josep

    2015-03-01

    Leaf senescence in winter deciduous species signals the transition from the active to the dormant stage. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. Photoperiod and temperature are the main cues controlling leaf senescence in winter deciduous species, with water stress imposing an additional influence. Photoperiod exerts a strict control on leaf senescence at latitudes where winters are severe and temperature gains importance in the regulation as winters become less severe. On average, climatic warming will delay and drought will advance leaf senescence, but at varying degrees depending on the species. Warming and drought thus have opposite effects on the phenology of leaf senescence, and the impact of climate change will therefore depend on the relative importance of each factor in specific regions. Warming is not expected to have a strong impact on nutrient proficiency although a slower speed of leaf senescence induced by warming could facilitate a more efficient nutrient resorption. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. The overall effects of climate change on nutrient resorption will depend on the contrasting effects of warming and drought. Changes in nutrient resorption and proficiency will impact production in the following year, at least in early spring, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling, especially if the changes are consequence of water stress.

  16. Variation in leaf litter production and resorption of nutrients in abundant tree species in Nyungwe tropical montane rainforest in Rwanda

    NASA Astrophysics Data System (ADS)

    Nyirambangutse, Brigitte; Mirindi Dusenge, Eric; Nsabimana, Donat; Bizuru, Elias; Pleijel, Håkan; Uddling, Johan; Wallin, Göran

    2014-05-01

    African tropical rainforests play many roles from local to global scale as providers of resources and ecosystem services. Although covering 30% of the global rainforest, only few studies aiming to better understand the storage and fluxes of carbon and nutrients in these forests have been conducted. To answer questions related to these issues, we have established 15 permanent 0.5 ha plots where we compare carbon and nutrient fluxes of primary and secondary forest tree communities in a tropical montane forest in central Africa. The studies are conducted in Nyungwe montane tropical rain forest gazetted as a National Park to protect its extensive floral and faunal diversity covering an area of 970 km2. Nyungwe is located in Southwest Rwanda (2o17'-2o50'S, 29o07'-29o26A'E). The forest is ranging between 1600-2950 m.a.s.l. and is one of the most biologically important rainforest in Albertine Rift region in terms of Biodiversity. Nyungwe consists of a mixture of primary and secondary forest communities supporting a richness of plant and animal life. More than 260 species of trees and shrubs have been found in Nyungwe, including species endemic to the Albertine Rift. The forest has a climate with a mean annual temperature of 15.5oC and annual rainfall of ca 1850 mm yr-1, with July and August being the only months when rainfall drops. A part of this study is focusing on the dynamics of nutrients through leaf turnover. This turnover of leaves is regulated to maximize the carbon gain through canopy photosynthesis and resource-use efficiency of the plant. It is known that about half of leaf nitrogen is invested in photosynthetic apparatus and that there normally is a strong correlation between the photosynthetic capacity and leaf nitrogen per unit area. Hence leaf nitrogen is an important factor for canopy photosynthesis. However, leaves are produced, senesce and fall. Some nitrogen in the leaf is lost when leaves senesce but other is resorbed. The resorption of nitrogen

  17. Leaf lifetime photosynthetic rate and leaf demography in whole plants of Ipomoea pes-caprae growing with a low supply of calcium, a ‘non-mobile’ nutrient

    PubMed Central

    Suárez, N.

    2010-01-01

    The adaptive significance of leaf longevity has been established in relation to restrictive nutrients that can be retranslocated within the plant. However, the effect of deficiencies in ‘non-mobile’ nutrients on leaf lifespan and photosynthetic carbon gain is uncertain. Calcium is frequently given as an example of an essential nutrient with low phloem mobility that may alter the leaf senescence process. This study has been designed to estimate leaf lifespan, leaf production (Lp) and leaf death (Ld) rates, the age structure of leaves, and the decline in maximum photosynthetic rate (Amax) with age in plants of Ipomoea pes-caprae growing with a full supply of nutrients and with a low Ca supply. The Ca deficiency produced reductions in Lp and leaf lifespan compared with control plants. In spite of the differences in the demographic parameters between treatments in control and low-Ca plants, the percentage of leaves of a given leaf age class is maintained in such a way that the number of leaves per plant continues to increase. No relationship was found between Ca supply and Amax. However, the decline in Amax with leaf senescence was rather sudden in control plants compared with plants growing with a low Ca supply. The importance of simultaneously using the total leaf demographic census and the assimilation rate along with leaf lifespan data in order to understand the performance of whole plants under constrained conditions is discussed. PMID:20080828

  18. Relative Contributions of Leaf-associated Microorganisms to Leaf Litter Breakdown in a Nutrient-enriched Headwater Stream

    NASA Astrophysics Data System (ADS)

    Tant, C. J.; Rosemond, A. D.; Taylor, N.; Conners, D. E.; Suberkropp, K.

    2005-05-01

    Litter decomposition in streams occurs as a function of microbial and invertebrate processing, as well as abiotic factors. Abiotic factors, such as streamwater nutrient concentrations, may change the relative importance of groups of microorganisms, as well as invertebrates, to leaf breakdown. We plan to quantify the relative contributions of bacteria, fungi, and invertebrate processing on decaying leaves in a reference and treatment stream (experimentally enriched with N & P for 4.5 yrs) at the Coweeta Long Term Ecological Research site in North Carolina, USA. Leaf packs of maple or rhododendron leaves were periodically retrieved to determine decay rates. Microbial activity was measured as respiration, fungal biomass was determined by measuring ergosterol concentration, and bacterial biomass was determined by epifluorescence microscopy. Breakdown rates were dramatically faster in the nutrient enriched stream than the reference stream, associated with greater microbial activity and presumably, invertebrate feeding. Based on whole-system response by microorganisms, we predict that nutrient enrichment will lead to greater contributions of fungi, relative to bacteria, to leaf breakdown. Our results show that enrichment can fundamentally alter the rate of organic matter breakdown in streams, and will test whether enrichment also changes the relative roles of groups of organisms contributing to breakdown processes.

  19. Effects of nutrient enrichment on mangrove leaf litter decomposition.

    PubMed

    Keuskamp, Joost A; Hefting, Mariet M; Dingemans, Bas J J; Verhoeven, Jos T A; Feller, Ilka C

    2015-03-01

    Nutrient enrichment of mangroves, a common phenomenon along densely populated coastlines, may negatively affect mangrove ecosystems by modifying internal carbon and nutrient cycling. The decomposition of litter exerts a strong influence on these processes and is potentially modified by eutrophication. This study describes effects of N and P enrichment on litter decomposition rate and mineralisation/immobilisation patterns. By making use of reciprocal litter transplantation experiments among fertiliser treatments, it was tested if nutrient addition primarily acts on the primary producers (i.e. changes in litter quantity and quality) or on the microbial decomposers (i.e. changes in nutrient limitation for decomposition). Measurements were done in two mangrove forests where primary production was either limited by N or by P, which had been subject to at least 5 years of experimental N and P fertilisation. Results of this study indicated that decomposers were always N-limited regardless of the limitation of the primary producers. This leads to a differential nutrient limitation between decomposers and primary producers in sites where mangrove production was P-limited. In these sites, fertilisation with P caused litter quality to change, resulting in a higher decomposition rate. This study shows that direct effects of fertilisation on decomposition through an effect on decomposer nutrient availability might be non-significant, while the indirect effects through modifying litter quality might be quite substantial in mangroves. Our results show no indication that eutrophication increases decomposition without stimulating primary production. Therefore we do not expect a decline in carbon sequestration as a result of eutrophication of mangrove ecosystems.

  20. Leaf nitrogen and phosphorus of temperate desert plants in response to climate and soil nutrient availability.

    PubMed

    He, Mingzhu; Dijkstra, Feike A; Zhang, Ke; Li, Xinrong; Tan, Huijuan; Gao, Yanhong; Li, Gang

    2014-11-06

    In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0-10 cm), middle (10-40 cm) and deep soil layers (40-100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N:P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect.

  1. Effects of nutrient addition on leaf chemistry, morphology, and photosynthetic capacity of three bog shrubs.

    PubMed

    Bubier, Jill L; Smith, Rose; Juutinen, Sari; Moore, Tim R; Minocha, Rakesh; Long, Stephanie; Minocha, Subhash

    2011-10-01

    Plants in nutrient-poor environments typically have low foliar nitrogen (N) concentrations, long-lived tissues with leaf traits designed to use nutrients efficiently, and low rates of photosynthesis. We postulated that increasing N availability due to atmospheric deposition would increase photosynthetic capacity, foliar N, and specific leaf area (SLA) of bog shrubs. We measured photosynthesis, foliar chemistry and leaf morphology in three ericaceous shrubs (Vaccinium myrtilloides, Ledum groenlandicum and Chamaedaphne calyculata) in a long-term fertilization experiment at Mer Bleue bog, Ontario, Canada, with a background deposition of 0.8 g N m(-2) a(-1). While biomass and chlorophyll concentrations increased in the highest nutrient treatment for C. calyculata, we found no change in the rates of light-saturated photosynthesis (A(max)), carboxylation (V(cmax)), or SLA with nutrient (N with and without PK) addition, with the exception of a weak positive correlation between foliar N and A(max) for C. calyculata, and higher V(cmax) in L. groenlandicum with low nutrient addition. We found negative correlations between photosynthetic N use efficiency (PNUE) and foliar N, accompanied by a species-specific increase in one or more amino acids, which may be a sign of excess N availability and/or a mechanism to reduce ammonium (NH(4)) toxicity. We also observed a decrease in foliar soluble Ca and Mg concentrations, essential minerals for plant growth, but no change in polyamines, indicators of physiological stress under conditions of high N accumulation. These results suggest that plants adapted to low-nutrient environments do not shift their resource allocation to photosynthetic processes, even after reaching N sufficiency, but instead store the excess N in organic compounds for future use. In the long term, bog species may not be able to take advantage of elevated nutrients, resulting in them being replaced by species that are better adapted to a higher nutrient environment.

  2. Environmental modification of yield and nutrient composition of 'Waldmann's Green' leaf lettuce

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Chun, C.; Brandt, W. E.; Nielsen, S. S.

    1997-01-01

    Leaf number, dry weight, and nutrient composition of Lactuca sativa L. cv. Waldmann's Green leaves were compared following 9 days of treatment in a controlled environment room under various combinations of photosynthetic photon flux (PPF:350 vs 800 micromoles m-2 s-1), atmospheric CO2 level (ambient vs 1500 micromoles mol-1), and single-strength (1X:15 mM) vs double-strength (2X:30 mM) nitrogen (N) as NO3- alone or as NH4(+) + NO3- (1:5 molar ratio). CO2 enrichment greatly enhanced leaf number under all PPF and N conditions, but increased leaf dry weight only at high PPF. Conditions favoring high photosynthesis enhanced leaf starch content 3-fold, and protein content increased as much as 64% with 2X NH4(+)+NO3-. Free sugar content was 6 to 9% of leaf dry weight for all treatment combinations, while fat was 1.5 to 3.5%. Ash content varied from 15 to 20% of leaf dry weight. Modified controlled environments can be used to enhance the nutritional content as well as the yield of crops to be used for life support in space-deployed, self-sustaining human habitats. Leaf lettuce is a useful model crop for demonstrating the potential of nutritional value added by environmental manipulation.

  3. Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency.

    PubMed

    Estiarte, Marc; Peñuelas, Josep

    2015-03-01

    Leaf senescence in winter deciduous species signals the transition from the active to the dormant stage. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. Photoperiod and temperature are the main cues controlling leaf senescence in winter deciduous species, with water stress imposing an additional influence. Photoperiod exerts a strict control on leaf senescence at latitudes where winters are severe and temperature gains importance in the regulation as winters become less severe. On average, climatic warming will delay and drought will advance leaf senescence, but at varying degrees depending on the species. Warming and drought thus have opposite effects on the phenology of leaf senescence, and the impact of climate change will therefore depend on the relative importance of each factor in specific regions. Warming is not expected to have a strong impact on nutrient proficiency although a slower speed of leaf senescence induced by warming could facilitate a more efficient nutrient resorption. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. The overall effects of climate change on nutrient resorption will depend on the contrasting effects of warming and drought. Changes in nutrient resorption and proficiency will impact production in the following year, at least in early spring, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling, especially if the changes are consequence of water stress. PMID:25384459

  4. Photosynthetic capacity of tropical montane tree species in relation to leaf nutrients, successional strategy and growth temperature.

    PubMed

    Dusenge, Mirindi Eric; Wallin, Göran; Gårdesten, Johanna; Niyonzima, Felix; Adolfsson, Lisa; Nsabimana, Donat; Uddling, Johan

    2015-04-01

    Photosynthetic capacity of tree leaves is typically positively related to nutrient content and little affected by changes in growth temperature. These relationships are, however, often poorly supported for tropical trees, for which interspecific differences may be more strongly controlled by within-leaf nutrient allocation than by absolute leaf nutrient content, and little is known regarding photosynthetic acclimation to temperature. To explore the influence of leaf nutrient status, successional strategy and growth temperature on the photosynthetic capacity of tropical trees, we collected data on photosynthetic, chemical and morphological leaf traits of ten tree species in Rwanda. Seven species were studied in a forest plantation at mid-altitude (~1,700 m), whereas six species were studied in a cooler montane rainforest at higher altitude (~2,500 m). Three species were common to both sites, and, in the montane rainforest, three pioneer species and three climax species were investigated. Across species, interspecific variation in photosynthetic capacity was not related to leaf nutrient content. Instead, this variation was related to differences in within-leaf nitrogen allocation, with a tradeoff between investments into compounds related to photosynthetic capacity (higher in pioneer species) versus light-harvesting compounds (higher in climax species). Photosynthetic capacity was significantly lower at the warmer site at 1,700 m altitude. We conclude that (1) within-leaf nutrient allocation is more important than leaf nutrient content per se in controlling interspecific variation in photosynthetic capacity among tree species in tropical Rwanda, and that (2) tropical montane rainforest species exhibit decreased photosynthetic capacity when grown in a warmer environment.

  5. Canopy and leaf composition drive patterns of nutrient release from pruning residues in a coffee agroforest.

    PubMed

    Tully, Katherine L; Lawrence, Deborah

    2012-06-01

    In a coffee agroforest, the crop is cultivated under the shade of fruit-bearing and nitrogen (N)-fixing trees. These trees are periodically pruned to promote flowering and fruiting as well as to make nutrients stored in tree biomass available to plants. We investigated the effect of canopy composition and substrate quality on decomposition rates and patterns of nutrient release from pruning residues in a coffee agroforest located in Costa Rica's Central Valley. Initial phosphorus (P) release was enhanced under a canopy composed solely of N-fixing, Erythrina poeppigiana compared to a mixed canopy of Erythrina and Musa acuminata (banana). Both initial and final N release were similar under the two canopy types. However, after five months of decomposition, a higher proportion of initial N had been released under the single canopy. Although patterns of decomposition and nutrient release were not predicted by initial substrate quality, mass loss in leaf mixtures rates were well predicted by mean mass loss of their component species. This study identifies specific pruning regimes that may regulate N and P release during crucial growth periods, and it suggests that strategic pruning can enhance nutrient availability. For example, during the onset of rapid fruit growth, a two-species mixture may release more P than a three-species mixture. However, by the time of the harvest, the two- and three-species mixtures have released roughly the same amount of N and P. These nutrients do not always follow the same pattern, as N release can be maximized in single-species substrates, while P release is often facilitated in species mixtures. Our study indicates the importance of management practices in mediating patterns of nutrient release. Future research should investigate how canopy composition and farm management can also mediate on-farm nutrient losses. PMID:22827139

  6. Canopy and leaf composition drive patterns of nutrient release from pruning residues in a coffee agroforest.

    PubMed

    Tully, Katherine L; Lawrence, Deborah

    2012-06-01

    In a coffee agroforest, the crop is cultivated under the shade of fruit-bearing and nitrogen (N)-fixing trees. These trees are periodically pruned to promote flowering and fruiting as well as to make nutrients stored in tree biomass available to plants. We investigated the effect of canopy composition and substrate quality on decomposition rates and patterns of nutrient release from pruning residues in a coffee agroforest located in Costa Rica's Central Valley. Initial phosphorus (P) release was enhanced under a canopy composed solely of N-fixing, Erythrina poeppigiana compared to a mixed canopy of Erythrina and Musa acuminata (banana). Both initial and final N release were similar under the two canopy types. However, after five months of decomposition, a higher proportion of initial N had been released under the single canopy. Although patterns of decomposition and nutrient release were not predicted by initial substrate quality, mass loss in leaf mixtures rates were well predicted by mean mass loss of their component species. This study identifies specific pruning regimes that may regulate N and P release during crucial growth periods, and it suggests that strategic pruning can enhance nutrient availability. For example, during the onset of rapid fruit growth, a two-species mixture may release more P than a three-species mixture. However, by the time of the harvest, the two- and three-species mixtures have released roughly the same amount of N and P. These nutrients do not always follow the same pattern, as N release can be maximized in single-species substrates, while P release is often facilitated in species mixtures. Our study indicates the importance of management practices in mediating patterns of nutrient release. Future research should investigate how canopy composition and farm management can also mediate on-farm nutrient losses.

  7. Preference and performance of a willow-feeding leaf beetle: soil nutrient and flooding effects on host quality.

    PubMed

    Lower, Steven S; Kirshenbaum, Sheril; Orians, Colin M

    2003-08-01

    The distribution and abundance of herbivores on plants growing under different environmental conditions may depend upon preference and/or performance. Soil nutrients and water availability are key determinants of herbivore distribution, as both influence plant growth and tissue quality. However, the effects of water on plant quality may depend upon the availability of nutrients and vice versa. Surprisingly few studies have examined the interactions between the two. We investigated the effects of soil nutrient and water availability on (1) the growth and chemistry of the silky willow (Salix sericea Marshall), and (2) the preference and performance of the imported willow leaf beetle (Plagiodera versicolora Laichartig). We conducted two common garden experiments using a similar 2x2 fully factorial design with two levels of soil nutrients (low, high) and two levels of water availability (field capacity, flooded). In the first experiment (larval performance), larval development time and pupal weight were not influenced by nutrient or water availability to the plant. This occurred despite the fact that plants in the high nutrient treatments had higher protein concentration and lower foliar concentrations of the phenolic glycoside 2'-cinnamoylsalicortin. In the second experiment (adult preference), we caged four plants (one from each treatment) and released beetles into cages. We found that plant growth and leaf protein depended upon the interaction between nutrient and water availability. Plant growth was greatest in the high nutrient-field capacity treatment and leaf protein was greatest in the high nutrient-flooded treatment. In contrast, adults settled and oviposited preferentially on the high nutrient treatment under flooded conditions, but we found no evidence of interactions between nutrients and water on preference. Thus, at least under flooded conditions nutrients affect adult preference. We also found that foliar protein was correlated positively with adult

  8. Leaf structure vs. nutrient relationships vary with soil conditions in temperate shrubs and trees

    NASA Astrophysics Data System (ADS)

    Niinemets, Ülo; Kull, Kalevi

    2003-09-01

    Often there are significant positive interspecific relationships between leaf area per unit dry mass (SLA) and foliar phosphorus and nitrogen concentrations ([P] and [N]). Most of these studies have been conducted on moderately acidic soils, and little is known of the generality of these relations as potentially affected by soil characteristics. We investigated foliage mineral composition in relation to leaf structure in a wooded meadow on calcareous alkaline soil, in a bog on strongly acidic soil, and in a flood plain on moderately acidic soil. Foliar nutrient contents and fertilization experiments indicated that foliage physiological activity was co-limited by both P and N availabilities in the wooded meadow, by P in the bog, and by N in the flood plain. In the wooded meadow and in the bog, there were positive relationships between SLA and P concentration ([P]), and no relationship between SLA and nitrogen concentration [N]. Given that the fraction of support tissues generally increases with decreasing SLA, the requirement for mineral nutrients is lower at low SLA. Thus, these contrasting relations between mineral nutrients and SLA suggest that P was distributed in a more "optimal" manner among the leaves with varying structure than N in P-limited communities. In the flood plain, SLA was positively related to both [P] and [N], possibly manifesting a strategy to cope with N limitations by enhancing N turnover, and accordingly, greater P requirement for nucleic acid formation in N-limited soils. Total variation in foliar structural and chemical characteristics was similar in all sites, and was mainly determined by variation among the species. Part of this variability was explained by life form and plant size. [P] was higher in trees than in shrubs, and [P] and P/N ratio increased with increasing total plant height, indicating that P nutrition was improved relative to N nutrition with increasing plant size. Since the capture of less mobile soil elements such as P is

  9. No evidence for leaf-trait dissimilarity effects on litter decomposition, fungal decomposers, and nutrient dynamics.

    PubMed

    Frainer, André; Moretti, Marcelo S; Xu, Wenjing; Gessner, Mark O

    2015-02-01

    Biodiversity and ecosystem-functioning theory suggest that litter mixtures composed of dissimilar leaf species can enhance decomposition due to species trait complementarity. Here we created a continuous gradient of litter chemistry trait variability within species mixtures to assess effects of litter dissimilarity on three related processes in a natural stream: litter decomposition, fungal biomass accrual in the litter, and nitrogen and phosphorus immobilization. Litter from a pool of eight leaf species was analyzed for chemistry traits affecting decomposition (lignin, nitrogen, and phosphorus) and assembled in all of the 28 possible two-species combinations. Litter dissimilarity was characterized in terms of a range of trait-diversity measures, using Euclidean and Gower distances and dendrogram-based indices. We found large differences in decomposition rates among leaf species, but no significant relationships between decomposition rate of individual leaf species and litter trait dissimilarity, irrespective of whether decomposition was mediated by microbes alone or by both microbes and litter-consuming invertebrates. Likewise, no effects of trait dissimilarity emerged on either fungal biomass accrual or changes during decomposition of nitrogen or phosphorus concentrations in individual leaf species. In line with recent meta-analyses, these results provide support for the contention that litter diversity effects on decomposition, at least in streams, are less pronounced than effects on terrestrial primary productivity.

  10. CO2 enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems

    NASA Astrophysics Data System (ADS)

    Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong

    2015-01-01

    As atmospheric CO2 concentration increases, many experiments have been carried out to study effects of CO2 enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO2 enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO2 and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO2 and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO2 and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO2 was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO2 and N addition will increase nutrient cycling in subtropical China under the future global change.

  11. CO2 enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems

    PubMed Central

    Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong

    2015-01-01

    As atmospheric CO2 concentration increases, many experiments have been carried out to study effects of CO2 enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO2 enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO2 and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO2 and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO2 and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO2 was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO2 and N addition will increase nutrient cycling in subtropical China under the future global change. PMID:25608664

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

    PubMed

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

    2014-12-01

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

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

    PubMed

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

    2014-12-01

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

  14. Extended leaf senescence promotes carbon gain and nutrient resorption: importance of maintaining winter photosynthesis in subtropical forests.

    PubMed

    Zhang, Yong-Jiang; Yang, Qiu-Yun; Lee, David W; Goldstein, Guillermo; Cao, Kun-Fang

    2013-11-01

    The relative advantages of being deciduous or evergreen in subtropical forests and the relationship between leaf phenology and nutrient resorption efficiency are not well understood. The most successful deciduous species (Lyonia ovalifolia) in an evergreen-dominated subtropical montane cloud forest in southwest (SW) China maintains red senescing leaves throughout much of the winter. The aim of this study was to investigate whether red senescing leaves of this species were able to assimilate carbon in winter, to infer the importance of maintaining a positive winter carbon balance in subtropical forests, and to test whether an extended leaf life span is associated with enhanced nutrient resorption and yearly carbon gain. The red senescing leaves of L. ovalifolia assimilated considerable carbon during part of the winter, resulting in a higher yearly carbon gain than co-occurring deciduous species. Its leaf N and P resorption efficiency was higher than for co-occurring non-anthocyanic deciduous species that dropped leaves in autumn, supporting the hypothesis that anthocyanin accumulation and/or extended leaf senescence help in nutrient resorption. Substantial winter carbon gain and efficient nutrient resorption may partially explain the success of L. ovalifolia versus that of the other deciduous species in this subtropical forest. The importance of maintaining a positive carbon balance for ecological success in this forest also provides indirect evidence for the dominance of evergreen species in the subtropical forests of SW China.

  15. Extended leaf senescence promotes carbon gain and nutrient resorption: importance of maintaining winter photosynthesis in subtropical forests.

    PubMed

    Zhang, Yong-Jiang; Yang, Qiu-Yun; Lee, David W; Goldstein, Guillermo; Cao, Kun-Fang

    2013-11-01

    The relative advantages of being deciduous or evergreen in subtropical forests and the relationship between leaf phenology and nutrient resorption efficiency are not well understood. The most successful deciduous species (Lyonia ovalifolia) in an evergreen-dominated subtropical montane cloud forest in southwest (SW) China maintains red senescing leaves throughout much of the winter. The aim of this study was to investigate whether red senescing leaves of this species were able to assimilate carbon in winter, to infer the importance of maintaining a positive winter carbon balance in subtropical forests, and to test whether an extended leaf life span is associated with enhanced nutrient resorption and yearly carbon gain. The red senescing leaves of L. ovalifolia assimilated considerable carbon during part of the winter, resulting in a higher yearly carbon gain than co-occurring deciduous species. Its leaf N and P resorption efficiency was higher than for co-occurring non-anthocyanic deciduous species that dropped leaves in autumn, supporting the hypothesis that anthocyanin accumulation and/or extended leaf senescence help in nutrient resorption. Substantial winter carbon gain and efficient nutrient resorption may partially explain the success of L. ovalifolia versus that of the other deciduous species in this subtropical forest. The importance of maintaining a positive carbon balance for ecological success in this forest also provides indirect evidence for the dominance of evergreen species in the subtropical forests of SW China. PMID:23636462

  16. Generation of Nutrients and Detoxification: Possible Roles of Yeasts in Leaf-Cutting Ant Nests.

    PubMed

    Mendes, Thais D; Rodrigues, André; Dayo-Owoyemi, Ifeloju; Marson, Fernando A L; Pagnocca, Fernando C

    2012-02-17

    The possible roles played by yeasts in attine ant nests are mostly unknown. Here we present our investigations on the plant polysaccharide degradation profile of 82 yeasts isolated from fungus gardens of Atta and Acromyrmex species to demonstrate that yeasts found in ant nests may play the role of making nutrients readily available throughout the garden and detoxification of compounds that may be deleterious to the ants and their fungal cultivar. Among the yeasts screened, 65% exhibited cellulolytic enzymes, 44% exhibited pectinolytic activity while 27% and 17% possess enzyme systems for the degradation of protease and amylase, respectively. Galacturonic acid, which had been reported in previous work to be poorly assimilated by the ant fungus and also to have a negative effect on ants' survival, was assimilated by 64% and 79% of yeasts isolated from nests of A. texana and Acromyrmex respectively. Our results suggest that yeasts found in ant nests may participate in generation of nutrients and removal of potentially toxic compounds, thereby contributing to the stability of the complex microbiota found in the leaf-cutting ant nests.

  17. Inheritance and QTL Mapping of Leaf Nutrient Concentration in a Cotton Inter-Specific Derived RIL Population.

    PubMed

    Liu, Shiming; Lacape, Jean-Marc; Constable, Greg A; Llewellyn, Danny J

    2015-01-01

    Developing and deploying cotton cultivars with high nutrient uptake, use efficiency and tolerance to nutrient related soil stresses is desirable to assist sustainable soil management. Genetic variation, heritability, selection response and quantitative trait loci (QTLs) were investigated for five macronutrients (P, K, Ca, Mg, S) and five micronutrients (Fe, Mn, B, Zn, and Cu) in a recombinant inbred line (RIL) population from an inter-specific cross between Gossypium hirsutum cv. Guazuncho 2, and G. barbadense accession VH8-4602. Na and K/Na ratio were also studied as the imbalance between Na and other nutrients is detrimental to cotton growth and development. The concentrations of nutrients were measured for different plant parts of the two parents and for leaf samples of the whole population collected at early to peak flowering in field experiments over two years in a sodic Vertosol soil. Parental contrast was large for most nutrient concentrations in leaves when compared with other plant parts. Segregation for leaf nutrient concentration was observed within the population with transgression for P, K, K/Na ratio and all micronutrients. Genotypic difference was the major factor behind within-population variation for most nutrients, while narrow sense heritability was moderate (0.27 for Mn and Cu, and 0.43 for B). At least one significant QTL was identified for each nutrient except K and more than half of those QTLs were clustered on chromosomes 14, 18 and 22. Selection response was predicted to be low for P and all micronutrients except B, high for K, Na and B, and very high for K/Na ratio. Correlations were more common between macronutrients, Na and K/Na ratio where the nature and strength of the relations varied (r=-0.69 to 0.76). We conclude that there is sufficient genetic diversity between these two tetraploid cotton species that could be exploited to improve cotton nutrient status by introgressing species-unique favourable alleles. PMID:26020945

  18. Inheritance and QTL Mapping of Leaf Nutrient Concentration in a Cotton Inter-Specific Derived RIL Population

    PubMed Central

    Liu, Shiming; Lacape, Jean-Marc; Constable, Greg A.; Llewellyn, Danny J.

    2015-01-01

    Developing and deploying cotton cultivars with high nutrient uptake, use efficiency and tolerance to nutrient related soil stresses is desirable to assist sustainable soil management. Genetic variation, heritability, selection response and quantitative trait loci (QTLs) were investigated for five macronutrients (P, K, Ca, Mg, S) and five micronutrients (Fe, Mn, B, Zn, and Cu) in a recombinant inbred line (RIL) population from an inter-specific cross between Gossypium hirsutum cv. Guazuncho 2, and G. barbadense accession VH8-4602. Na and K/Na ratio were also studied as the imbalance between Na and other nutrients is detrimental to cotton growth and development. The concentrations of nutrients were measured for different plant parts of the two parents and for leaf samples of the whole population collected at early to peak flowering in field experiments over two years in a sodic Vertosol soil. Parental contrast was large for most nutrient concentrations in leaves when compared with other plant parts. Segregation for leaf nutrient concentration was observed within the population with transgression for P, K, K/Na ratio and all micronutrients. Genotypic difference was the major factor behind within-population variation for most nutrients, while narrow sense heritability was moderate (0.27 for Mn and Cu, and 0.43 for B). At least one significant QTL was identified for each nutrient except K and more than half of those QTLs were clustered on chromosomes 14, 18 and 22. Selection response was predicted to be low for P and all micronutrients except B, high for K, Na and B, and very high for K/Na ratio. Correlations were more common between macronutrients, Na and K/Na ratio where the nature and strength of the relations varied (r=-0.69 to 0.76). We conclude that there is sufficient genetic diversity between these two tetraploid cotton species that could be exploited to improve cotton nutrient status by introgressing species-unique favourable alleles. PMID:26020945

  19. Leaf-mining by Phyllonorycter blancardella reprograms the host-leaf transcriptome to modulate phytohormones associated with nutrient mobilization and plant defense.

    PubMed

    Zhang, Hui; Dugé de Bernonville, Thomas; Body, Mélanie; Glevarec, Gaëlle; Reichelt, Michael; Unsicker, Sybille; Bruneau, Maryline; Renou, Jean-Pierre; Huguet, Elisabeth; Dubreuil, Géraldine; Giron, David

    2016-01-01

    Phytohormones have long been hypothesized to play a key role in the interactions between plant-manipulating organisms and their host-plants such as insect-plant interactions that lead to gall or 'green-islands' induction. However, mechanistic understanding of how phytohormones operate in these plant reconfigurations is lacking due to limited information on the molecular and biochemical phytohormonal modulation following attack by plant-manipulating insects. In an attempt to fill this gap, the present study provides an extensive characterization of how the leaf-miner Phyllonorycter blancardella modulates the major phytohormones and the transcriptional activity of plant cells in leaves of Malus domestica. We show here, that cytokinins strongly accumulate in mined tissues despite a weak expression of plant cytokinin-related genes. Leaf-mining is also associated with enhanced biosynthesis of jasmonic acid precursors but not the active form, a weak alteration of the salicylic acid pathway and a clear inhibition of the abscisic acid pathway. Our study consolidates previous results suggesting that insects may produce and deliver cytokinins to the plant as a strategy to manipulate the physiology of the leaf to create a favorable nutritional environment. We also demonstrate that leaf-mining by P. blancardella leads to a strong reprogramming of the plant phytohormonal balance associated with increased nutrient mobilization, inhibition of leaf senescence and mitigation of plant direct and indirect defense.

  20. Leaf nutrient contents and morphology of invasive tamarisk in different soil conditions in the lower Virgin River

    NASA Astrophysics Data System (ADS)

    Imada, S.; Acharya, K.; Tateno, R.; Yamanaka, N.

    2012-12-01

    Invasive plants can alter ecosystem nitrogen (N) cycling. To increase our understanding of nutrient use strategy of invasive tamarisk (Tamarix spp.) on an arid riparian ecosystem, we examined leaf nutrient contents and morphology of Tamarix ramosissima and its relationship with soil properties in the lower Virgin River floodplain, Nevada, U.S. Leaves were collected in three different locations; near the river, near the stand edge (60-70 m from the river edge) and at 30-40 m from the river edge in the summer of 2011. Leaves were analyzed for carbon (C) and N contents, and specific leaf area (SLA). Soil samples at 10-20 cm depths and under the canopy were also collected for soil water, pH, electrical conductivity (EC) and inorganic nitrogen (NO3- and NH4+) analysis. Results suggested that tree size and SLA increased with decreasing distance from the river, whereas C isotope discrimination did not differ among the samples based on distance from the river. Nitrogen content per unit mass and N isotope discrimination (δ15N) were significantly higher in the trees near the river. Soil NO3- and total inorganic N had positive relationships with δ15N in leaves, which suggests that leaf δ15N may be influenced by N concentrations on the soil surface. Negative correlations were found between soil EC and leaf N contents, suggesting that high soil salinity may decrease Tamarix leaf N and thus limit tree growth.

  1. Vitamin E in cranes: reference ranges and nutrient interactions

    USGS Publications Warehouse

    Dierenfeld, Ellen S.; Sheppard, C.D.; Langenberg, J.; Mirande, C.; Spratt, J.; Dein, F.J.

    1993-01-01

    Fat soluble vitamins E and A (quantified as alpha-tocopherol and all-trans retinol, respectively) were measured in plasma samples from 274 captive cranes from four institutions and five free-ranging birds. Ages ranged from 4 mo to 80 yr, and all 15 crane species were represented. Captive cranes had a mean +/- standard error (SE) of 6.57 +/- 0.82 micrograms/ml alpha-tocopherol; migrating greater sandhill cranes (Grus canadenis tabida) had a plasma concentration of 3.71 +/- 0.22 micrograms/ml. Sex and age differences were not significant, but crane species that evolved in temperate habitats had higher circulating levels of alpha-tocopherol than tropical or subtropical species. Mean +/- SE retinol values were 0.69 +/- 0.05 micrograms/ml in captive cranes, and 0.66 +/- 0.08 micrograms/ml in free-ranging cranes; values did not differ significantly by sex, age, or species. Dietary vitamin E concentrations were significantly correlated with plasma alpha-tocopherol levels in a logarithmic relationship. Dietary selenium at 0.5 mg/kg was associated with decreased circulating alpha-tocopherol concentrations.

  2. Photosynthetic capacity is negatively correlated with the concentration of leaf phenolic compounds across a range of different species

    PubMed Central

    Sumbele, Sally; Fotelli, Mariangela N.; Nikolopoulos, Dimosthenis; Tooulakou, Georgia; Liakoura, Vally; Liakopoulos, Georgios; Bresta, Panagiota; Dotsika, Elissavet; Adams, Mark A.; Karabourniotis, George

    2012-01-01

    Background and aims Phenolic compounds are the most commonly studied of all secondary metabolites because of their significant protective–defensive roles and their significant concentration in plant tissues. However, there has been little study on relationships between gas exchange parameters and the concentration of leaf phenolic compounds (total phenolics (TP) and condensed tannins (CT)) across a range of species. Therefore, we addressed the question: is there any correlation between photosynthetic capacity (Amax) and TP and CT across species from different ecosystems in different continents? Methodology A plethora of functional and structural parameters were measured in 49 plant species following different growth strategies from five sampling sites located in Greece and Australia. The relationships between several leaf traits were analysed by means of regression and principal component analysis. Principal results The results revealed a negative relationship between TP and CT and Amax among the different plant species, growth strategies and sampling sites, irrespective of expression (with respect to mass, area or nitrogen content). Principal component analysis showed that high concentrations of TP and CT are associated with thick, dense leaves with low nitrogen. This leaf type is characterized by low growth, Amax and transpiration rates, and is common in environments with low water and nutrient availability, high temperatures and high light intensities. Therefore, the high TP and CT in such leaves are compatible with the protective and defensive functions ascribed to them. Conclusions Our results indicate a functional integration between carbon gain and the concentration of leaf phenolic compounds that reflects the trade-off between growth and defence/protection demands, depending on the growth strategy adopted by each species. PMID:23050073

  3. Spring leaf phenology and the diurnal temperature range in a temperate maple forest.

    PubMed

    Hanes, Jonathan M

    2014-03-01

    Spring leaf phenology in temperate climates is intricately related to numerous aspects of the lower atmosphere [e.g., surface energy balance, carbon flux, humidity, the diurnal temperature range (DTR)]. To further develop and improve the accuracy of ecosystem and climate models, additional investigations of the specific nature of the relationships between spring leaf phenology and various ecosystem and climate processes are required in different environments. This study used visual observations of maple leaf phenology, below-canopy light intensities, and micrometeorological data collected during the spring seasons of 2008, 2009, and 2010 to examine the potential influence of leaf phenology on a seasonal transition in the trend of the DTR. The timing of a reversal in the DTR trend occurred near the time when the leaves were unfolding and expanding. The results suggest that the spring decline in the DTR can be attributed primarily to the effect of canopy closure on daily maximum temperature. These findings improve our understanding of the relationship between leaf phenology and the diurnal temperature range in temperate maple forests during the spring. They also demonstrate the necessity of incorporating accurate phenological data into ecosystem and climate models and warrant a careful examination of the extent to which canopy phenology is currently incorporated into existing models.

  4. Impact of mycorrhization on the abundance, growth and leaf nutrient status of ferns along a tropical elevational gradient.

    PubMed

    Kessler, Michael; Güdel, Ramona; Salazar, Laura; Homeier, Jürgen; Kluge, Jürgen

    2014-07-01

    Mycorrhizal fungi are crucial for the ecological success of land plants, providing their hosts with nutrients in exchange for organic C. However, not all plants are mycorrhizal, especially ferns, of which about one-third of the species lack this symbiosis. Because the mycorrhizal status is evolutionarily ancestral, this lack of mycorrhizae must have ecological advantages, but what these advantages are and how they affect the competitive ability of non-mycorrhizal plants under natural conditions is currently unknown. To address this uncertainty, we studied terrestrial fern assemblages and species abundances as well as their mycorrhization status, leaf nutrient concentration and relative annual growth along an elevational gradient in the Ecuadorian Andes (500-4,000 m). We surveyed the mycorrhizal status of 375 root samples belonging to 85 species, and found mycorrhizae in 89% of the samples. The degree of mycorrhization decreased with elevation but was unrelated to soil nutrients. Species with mycorrhizae were significantly more abundant than non-mycorrhizal species, but non-mycorrhizal species had significantly higher relative growth and concentrations of leaf N, P, Mg, and Ca. Our study thus shows that despite lower abundances, non-mycorrhizal fern species did not appear to be limited in their growth or nutrient supply relative to mycorrhizal ones. As a basis for future studies, we hypothesize that non-mycorrhizal fern species may be favoured in special microhabitats of the forest understory with high soil nutrient or water availability, or that the ecological benefit of mycorrhizae is not related to nutrient uptake but rather to, for example, pathogen resistance.

  5. Interspecific variation in leaf pigments and nutrients of five tree species from a subtropical forest in southern Brazil.

    PubMed

    Bündchen, Márcia; Boeger, Maria Regina T; Reissmann, Carlos B; Geronazzo, Kelly M

    2016-01-01

    The purpose of this study was to analyze the seasonal variation in the nutrient and pigment content of leaves from five tree species - of which three are perennial (Cupania vernalis, Matayba elaeagnoides and Nectandra lanceolata) and two are deciduous (Cedrela fissilis and Jacaranda micrantha) - in an ecotone between a Deciduous Seasonal Forest and a Mixed Ombrophilous Forest in the state of Santa Catarina, Brazil. Leaf samples were collected in the four seasons of the year to determine the content of macronutrients (N, K, P, Mg, Ca, S) and photosynthetic pigments (Chla, Chlb, Chltot, Cartot, Chla:Chlb and Cartot:Chltot). The principal component analysis showed that leaf pigments contributed to the formation of the first axis, which explains most of the data variance for all species, while leaf nutrient contribution showed strong interspecific variation. These results demonstrate that the studied species have different strategies for acquisition and use of mineral resources and acclimation to light, which are determinant for them to coexist in the forest environment.

  6. Interspecific variation in leaf pigments and nutrients of five tree species from a subtropical forest in southern Brazil.

    PubMed

    Bündchen, Márcia; Boeger, Maria Regina T; Reissmann, Carlos B; Geronazzo, Kelly M

    2016-01-01

    The purpose of this study was to analyze the seasonal variation in the nutrient and pigment content of leaves from five tree species - of which three are perennial (Cupania vernalis, Matayba elaeagnoides and Nectandra lanceolata) and two are deciduous (Cedrela fissilis and Jacaranda micrantha) - in an ecotone between a Deciduous Seasonal Forest and a Mixed Ombrophilous Forest in the state of Santa Catarina, Brazil. Leaf samples were collected in the four seasons of the year to determine the content of macronutrients (N, K, P, Mg, Ca, S) and photosynthetic pigments (Chla, Chlb, Chltot, Cartot, Chla:Chlb and Cartot:Chltot). The principal component analysis showed that leaf pigments contributed to the formation of the first axis, which explains most of the data variance for all species, while leaf nutrient contribution showed strong interspecific variation. These results demonstrate that the studied species have different strategies for acquisition and use of mineral resources and acclimation to light, which are determinant for them to coexist in the forest environment. PMID:26959320

  7. Photosynthetic capacity, nutrient status, and growth of maize (Zea mays L.) upon MgSO4 leaf-application

    PubMed Central

    Jezek, Mareike; Geilfus, Christoph-Martin; Bayer, Anne; Mühling, Karl-Hermann

    2015-01-01

    The major plant nutrient magnesium (Mg) is involved in numerous physiological processes and its deficiency can severely reduce the yield and quality of crops. Since Mg availability in soil and uptake into the plant is often limited by unfavorable soil or climatic conditions, application of Mg onto leaves, the site with highest physiological Mg demand, might be a reasonable alternative fertilization strategy. This study aimed to investigate, if MgSO4 leaf-application in practically relevant amounts can efficiently alleviate the effects of Mg starvation in maize, namely reduced photosynthesis capacity, disturbed ion homeostasis and growth depression. Results clearly demonstrated that Mg deficiency could be mitigated by MgSO4 leaf-application as efficiently as by resupply of MgSO4 via the roots in vegetative maize plants. Significant increases in SPAD values and net rate of CO2-assimilation as well as enhanced shoot biomass have been achieved. Ion analysis furthermore revealed an improvement of the nutrient status of Mg-deficient plants with regard to [Mg], [K], and [Mn] in distinct organs, thereby reducing the risk of Mn-toxicity at the rootside, which often occurs together with Mg deficiency on acid soils. In conclusion, foliar fertilization with Mg proved to be an efficient strategy to adequately supply maize plants with Mg and might hence be of practical relevance to correct nutrient deficiencies during the growing season. PMID:25620973

  8. Adventitious roots, leaf abscission and nutrient status of flooded Gmelina and Tectona seedlings.

    PubMed

    Osundina, M A; Osonubi, O

    1989-12-01

    When flooded, seedlings of Gmelina arborea Roxb. produced more adventitious roots, had lower foliar Mn concentrations and lost fewer leaves than seedlings of Tectona grandis L.f. Severing the adventitious roots produced by flooded Gmelina seedlings increased leaf Mn concentration and leaf abscission and reduced whole-plant dry matter production. Flooded Gmelina cuttings, which do not produce adventitious roots, abscised few leaves until foliar concentrations of Mn and Fe had risen substantially above those of unflooded cuttings, at which time most leaves were shed. The results indicate that the development of adventitious roots in flooded seedlings of Gmelina suppressed uptake of Mn thereby minimizing leaf abscission. PMID:14972970

  9. Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates

    PubMed Central

    Blackman, Chris J.; Gleason, Sean M.; Chang, Yvonne; Cook, Alicia M.; Laws, Claire; Westoby, Mark

    2014-01-01

    Background and Aims Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species' climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate across species and sites remains to be tested. Methods Leaf hydraulic vulnerability to drought (P50leaf, the water potential inducing 50 % loss in hydraulic function) was measured in a diverse group of 92 woody, mostly evergreen angiosperms from sites across a wide range of habitats. These new data together with some previously published were tested against key climate indices related to water availability. Differences in within-site variability in P50leaf between sites were also examined. Key Results Values of hydraulic vulnerability to drought in leaves decreased strongly (i.e. became more negative) with decreasing annual rainfall and increasing aridity across sites. The standard deviation in P50leaf values recorded within each site was positively correlated with increasing aridity. P50leaf was also a good indicator of the climatic envelope across each species' distributional range as well as their dry-end distributional limits within Australia, although this relationship was not consistently detectable within sites. Conclusions The findings indicate that species sorting processes have influenced distributional patterns of P50leaf across the rainfall spectrum, but alternative strategies for dealing with water deficit exist within sites. The strong link to aridity suggests leaf hydraulic vulnerability may influence plant distributions under future climates. PMID:25006181

  10. Estimating Apparent Nutrient Digestibility of Diets Containing Leucaena leucocephala or Moringa oleifera Leaf Meals for Growing Rabbits by Two Methods

    PubMed Central

    Safwat, A. M.; Sarmiento-Franco, L.; Santos-Ricalde, R. H.; Nieves, D.; Sandoval-Castro, C. A.

    2015-01-01

    This study aimed to evaluate the nutrient digestibility of growing rabbits fed diets with different levels of either Leucaena leucocephala (LLM) or Moringa oleifera (MOLM) leaf meals and also to compare total collection and TiO2 marker methods for estimating digestibility. A total of 30 California growing rabbits (1.81±0.19 kg live weight on average) were randomly distributed into five experimental groups of six rabbits each and were housed in individual cages. The groups were control, 30% LLM, 40% LLM, 30% MOLM, and 40% MOLM. All groups received pelleted diets for two weeks; diets also contained 4 g/kg titanium dioxide as dietary marker. Daily feed intake was recorded during the whole experimental period and total feces were collected daily and weighed individually during four days. The results showed that there were no difference (p>0.05) in feed, dry matter (DM), organic matter (OM), crude protein (CP), digestible energy, and crude fiber (CF) intake between the control group and the other experimental groups. The apparent digestibility values of DM, OM, CP, CF, acid detergent fiber, and gross energy were the highest for control group (p = 0.001), meanwhile MOLM diets had generally higher nutrient digestibility coefficients than LLM diets. Increasing the inclusion level of leaf meal in the diet from 30% to 40% improved the digestibility of CF from 45.02% to 51.69% for LLM and from 48.11% to 55.89% for MOLM. Similar results for apparent nutrient digestibility coefficients were obtained when either total collection or indigestible marker method was used. In conclusion, the digestibility of MOLM containing diets were better than LLM diets, furthermore TiO2 as an external marker could be used as a simple, practical and reliable method to estimate nutrients digestibility in rabbit diets. PMID:26104524

  11. Estimating Apparent Nutrient Digestibility of Diets Containing Leucaena leucocephala or Moringa oleifera Leaf Meals for Growing Rabbits by Two Methods.

    PubMed

    Safwat, A M; Sarmiento-Franco, L; Santos-Ricalde, R H; Nieves, D; Sandoval-Castro, C A

    2015-08-01

    This study aimed to evaluate the nutrient digestibility of growing rabbits fed diets with different levels of either Leucaena leucocephala (LLM) or Moringa oleifera (MOLM) leaf meals and also to compare total collection and TiO2 marker methods for estimating digestibility. A total of 30 California growing rabbits (1.81±0.19 kg live weight on average) were randomly distributed into five experimental groups of six rabbits each and were housed in individual cages. The groups were control, 30% LLM, 40% LLM, 30% MOLM, and 40% MOLM. All groups received pelleted diets for two weeks; diets also contained 4 g/kg titanium dioxide as dietary marker. Daily feed intake was recorded during the whole experimental period and total feces were collected daily and weighed individually during four days. The results showed that there were no difference (p>0.05) in feed, dry matter (DM), organic matter (OM), crude protein (CP), digestible energy, and crude fiber (CF) intake between the control group and the other experimental groups. The apparent digestibility values of DM, OM, CP, CF, acid detergent fiber, and gross energy were the highest for control group (p = 0.001), meanwhile MOLM diets had generally higher nutrient digestibility coefficients than LLM diets. Increasing the inclusion level of leaf meal in the diet from 30% to 40% improved the digestibility of CF from 45.02% to 51.69% for LLM and from 48.11% to 55.89% for MOLM. Similar results for apparent nutrient digestibility coefficients were obtained when either total collection or indigestible marker method was used. In conclusion, the digestibility of MOLM containing diets were better than LLM diets, furthermore TiO2 as an external marker could be used as a simple, practical and reliable method to estimate nutrients digestibility in rabbit diets. PMID:26104524

  12. [Effects of elevated O3 on leaf litter decomposition and nutrient release of Quercus mongolica in city].

    PubMed

    Su, Li-li; Xu, Sheng; Fu, Wei; He, Xing-yuan; Chen, Wei; Zhao, Yi; Ping, Qin

    2016-02-01

    The leaf litters of 10-year-old Quercus mongolica were put in nylon bags and exposed to elevated 03 level (120 nmol . mol-1) with the control of 40 nmol . mol-1 in open top chambers (OTCs) for 150 days to test the effect of high O3 on the litter decomposition. The results showed that no significant difference was observed in residual mass between elevated O3 treatment and the control. Elevated 03 inhibited the release of C and K during the decomposition, the residual rate of K under elevated O3 treatment (23.9%) was significantly higher than that of the control (17.1%) after 150-day decomposition. Compared with the control, N mineralization and lignin degradation in elevated O3 treatment were inhibited during early period of decomposition (0-60 d), but were promoted in later period (90-150 d). The changes of lignin/N showed no significant difference between elevated O3 treatment and the control during the decomposition. Elevated O3 generally promoted the release of P in leaf litter of Q. mongolica during the decomposition. C/P ratio was higher under elevated 03 than that under control. Significant positive correlation was shown between residual dry mass of leaf litters and the residual rate of C, N, K, C/N ratio during decomposition. Elevated 03 might play an important role in the nutrient cycle of forest ecosystem in high-O3 pollution area.

  13. [Effects of elevated O3 on leaf litter decomposition and nutrient release of Quercus mongolica in city].

    PubMed

    Su, Li-li; Xu, Sheng; Fu, Wei; He, Xing-yuan; Chen, Wei; Zhao, Yi; Ping, Qin

    2016-02-01

    The leaf litters of 10-year-old Quercus mongolica were put in nylon bags and exposed to elevated 03 level (120 nmol . mol-1) with the control of 40 nmol . mol-1 in open top chambers (OTCs) for 150 days to test the effect of high O3 on the litter decomposition. The results showed that no significant difference was observed in residual mass between elevated O3 treatment and the control. Elevated 03 inhibited the release of C and K during the decomposition, the residual rate of K under elevated O3 treatment (23.9%) was significantly higher than that of the control (17.1%) after 150-day decomposition. Compared with the control, N mineralization and lignin degradation in elevated O3 treatment were inhibited during early period of decomposition (0-60 d), but were promoted in later period (90-150 d). The changes of lignin/N showed no significant difference between elevated O3 treatment and the control during the decomposition. Elevated O3 generally promoted the release of P in leaf litter of Q. mongolica during the decomposition. C/P ratio was higher under elevated 03 than that under control. Significant positive correlation was shown between residual dry mass of leaf litters and the residual rate of C, N, K, C/N ratio during decomposition. Elevated 03 might play an important role in the nutrient cycle of forest ecosystem in high-O3 pollution area. PMID:27396107

  14. [Developmental stability of a leaf of Pisum sativum L. under the influence of formaldehyde in a wide range of doses].

    PubMed

    Erofeeva, E A

    2012-01-01

    The influence of formaldehyde in a wide range of doses on the stability of development of the third leaf of pea (Pisum sativum L.) was studied. The developmental stability of the leaf was assessed by the change in the value of the directional asymmetry of the right and left leaflets caused by the fluctuating asymmetry of these morphological structures. When subjected to a toxic agent, the studied parameter exhibited a paradoxical effect. In minimum studied concentrations, formaldehyde disturbed stability of leaf development, which was manifested in an increase in the asymmetry of the right and left leaflets. At medium concentrations of the toxicant, the asymmetry was less than the control level, which indicated an increase in the developmental stability of the pea leaf. Maximum studied concentrations of formaldehyde, close to sublethal, again reduced the stability of development of the pea leaf and led to an increase in the asymmetry of its leaflets compared with the controls.

  15. Genetic diversity, host range, and distribution of tomato yellow leaf curl virus in Iran.

    PubMed

    Shirazi, M; Mozafari, J; Rakhshandehroo, F; Shams-Bakhsh, M

    2014-01-01

    Tomato yellow leaf curl virus (TYLCV) is considered one of the most important tomato pathogens in tropical and subtropical regions including Iran. During the years 2007 to 2009, a total number of 510 symptomatic and asymptomatic vegetable, ornamental and weed samples were collected from fields and greenhouses in ten provinces of Iran. Symptoms included stunting, yellowing, leaf curl and flower senescence. PCR with specific primers showed TYLCV infection in 184 samples (36%) such as cucumber, pepper, tomato and several weeds from seven provinces. Based on the geographical origin, host range and symptoms, twenty three representative isolates were selected for phylogenetic analysis. An amplicon with a size about 608 base pair (bp) comprising partial sequence of the coat (CP) and movement protein (MP) coding regions of the viral genome was sequenced and compared with the corresponding selected sequences available in GenBank for Iran and worldwide. Phylogenetic analyses on the basis of the nucleotide sequences indicated two geographically separated clades. Isolates collected from Hormozgan, Khuzestan and Kerman provinces were grouped together with other Iranian isolates including TYLCV-Ir2, TYLCV-Kahnooj, and an isolate from Oman. It was also revealed that isolates collected from Boushehr, Fars, Tehran, and Isfahan placed close to the Iranian isolate TYLCV-Abadeh and isolates from Israel and Egypt. No correlation was found between the genetic variation and the host species, but selected Iranian isolates were grouped on the basis of the geographical origins. Results of this study indicated a high genetic diversity among Iranian TYLCV isolates. PMID:24957717

  16. Leaf litter decomposition of four different deciduous tree species - resource stoichiometry, nutrient release and microbial community composition

    NASA Astrophysics Data System (ADS)

    Leitner, S.; Keiblinger, K. M.; Zechmeister-Boltenstern, S.

    2012-04-01

    Recently, there has been increasing interest in the role of microbial communities for ecosystem processes like litter decomposition and nutrient cycling. For example, fungi are thought to be key players during litter decomposition in terrestrial ecosystems because they are able to degrade recalcitrant compounds like lignin and also dominate the decomposition of cellulose and hemicellulose, whereas bacteria seem to play an important role for lignin decomposition especially under anaerobic conditions. However, our knowledge about the contribution of bacteria and fungi to decomposition is still scarce. The aim of the present study was to elucidate how the microbial decomposer community is affected by resource stoichiometry and how changes in community composition affect litter decomposition and nutrient cycling. To this end, we collected leaf litter of four deciduous tree species (beech (Fagus), oak (Quercus), alder (Alnus) and ash tree (Fraxinus)) at four different seasons (winter, spring, summer and autumn) in an Austrian forest (Schottenwald, 48°14'N16°15'E; MAT=9°C; soil type: dystric cambiosol; soil C:N=16) in 2010. We determined litter nutrient content (micro- and macronutrients) and extractable nutrients and assessed the microbial community by PFLA analysis to test the following hypotheses: (i) tree species affects microbial community composition, (ii) microbial community composition changes over the course of the year, and (iii) narrow litter C:nutrient ratios favour nutrient release. Our data show that litter of different tree species varied in their stoichiometry, with C:N ratios between 16 (alder) and 46 (beech) and C:P ratios between 309 (ash) and 1234 (alder). Tree species had a significant impact on microbial community composition: highest amounts of actinomycetes and protozoa were observed for alder, while arbuscular mycorrhizae were lowest for oak. Bacteria were favoured by litter with narrow C:N shortly after litterfall. During litter decomposition

  17. Leaf and soil nitrogen and phosphorus availability in a neotropical rain forest of nutrient-rich soil.

    PubMed

    Martínez-Sánchez, José Luis

    2006-06-01

    The nitrogen and phosphorus supply in a lowland rain forest with a nutrient-rich soil was investigated by means of the leaf N/P quotient. It was hypothesised a high N and P supply to the forest ecosystem with a N and P rich soil. Total N and extractable P were determined in the surface (10 cm) soil of three plots of the forest. Total N was analysed by the Kjeldahl method, and P was extracted with HCI and NH4F. The leaf N/P quotient was evaluated from the senesced leaves of 11 dominant tree species from the mature forest. Samples of 5 g of freshly fallen leaves were collected from three trees of each species. Nitrogen was analysed by microkjeldahl digestion with sulphuric acid and distilled with boric acid, and phosphorus was analysed by digestion with nitric acid and perchloric acid, and determined by photometry. Concentrations of total N (0.50%, n = 30) and extractable P (4.11 microg g(-1), n = 30) in the soil were high. As expected, P supply was sufficient, but contrary to expected, N supply was low (N/P = 11.8, n = 11).

  18. Predicting leaf gravimetric water content from foliar reflectance across a range of plant species using continuous wavelet analysis.

    PubMed

    Cheng, Tao; Rivard, Benoit; Sánchez-Azofeifa, Arturo G; Féret, Jean-Baptiste; Jacquemoud, Stephane; Ustin, Susan L

    2012-08-15

    Leaf water content is an important variable for understanding plant physiological properties. This study evaluates a spectral analysis approach, continuous wavelet analysis (CWA), for the spectroscopic estimation of leaf gravimetric water content (GWC, %) and determines robust spectral indicators of GWC across a wide range of plant species from different ecosystems. CWA is both applied to the Leaf Optical Properties Experiment (LOPEX) data set and a synthetic data set consisting of leaf reflectance spectra simulated using the leaf optical properties spectra (PROSPECT) model. The results for the two data sets, including wavelet feature selection and GWC prediction derived using those features, are compared to the results obtained from a previous study for leaf samples collected in the Republic of Panamá (PANAMA), to assess the predictive capabilities and robustness of CWA across species. Furthermore, predictive models of GWC using wavelet features derived from PROSPECT simulations are examined to assess their applicability to measured data. The two measured data sets (LOPEX and PANAMA) reveal five common wavelet feature regions that correlate well with leaf GWC. All three data sets display common wavelet features in three wavelength regions that span 1732-1736 nm at scale 4, 1874-1878 nm at scale 6, and 1338-1341 nm at scale 7 and produce accurate estimates of leaf GWC. This confirms the applicability of the wavelet-based methodology for estimating leaf GWC for leaves representative of various ecosystems. The PROSPECT-derived predictive models perform well on the LOPEX data set but are less successful on the PANAMA data set. The selection of high-scale and low-scale features emphasizes significant changes in both overall amplitude over broad spectral regions and local spectral shape over narrower regions in response to changes in leaf GWC. The wavelet-based spectral analysis tool adds a new dimension to the modeling of plant physiological properties with

  19. Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range

    USGS Publications Warehouse

    Cross, Alison; Perakis, Steven S.

    2011-01-01

    Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests.

  20. Population variation and natural selection on leaf traits in cork oak throughout its distribution range

    NASA Astrophysics Data System (ADS)

    Ramírez-Valiente, José Alberto; Valladares, Fernando; Sánchez-Gómez, David; Delgado, Antonio; Aranda, Ismael

    2014-07-01

    A central issue in evolutionary biology is the exploration of functional trait variation among populations and the extent to which this variation has adaptive value. It was recently proposed that specific leaf area (SLA), leaf nitrogen concentration per mass (Nmass) and water use efficiency in cork oak play an important role in adaptation to water availability in the environment. In order to investigate this hypothesis, we explored, first, whether there was population-level variation in cork oak (Quercus suber) for these functional traits throughout its distribution range; if this were the case, it would be consistent with the hypothesis that different rainfall patterns have led to ecotypic differentiation in this species. Second, we studied whether the population-level variation matched short-term selection on these traits under different water availability conditions using two fitness components: survival and growth. We found high population-level differentiation in SLA and Nmass, with populations from dry places exhibiting the lowest values for SLA and Nmass. Likewise, reduced SLA had fitness benefits in terms of growth for plants under dry conditions. However, contrary to our expectations, we did not find any pattern of association between functional traits and survival in nine-year-old saplings despite considerable drought during one year of the study period. These results together with findings from the literature suggest that early stages of development are the most critical period for this species. Most importantly, these findings suggest that cork oak saplings have a considerable potential to cope with dry conditions. This capacity to withstand aridity has important implications for conservation of cork oak woodlands under the ongoing climate change.

  1. Photosynthetic capacities of mature tropical forest trees in Rwanda are linked to successional group identity rather than to leaf nutrient content

    NASA Astrophysics Data System (ADS)

    Dusenge, Mirindi Eric; Wallin, Göran; Gårdesten, Johanna; Adolfsson, Lisa; Niyonzima, Felix; Nsabimana, Donat; Uddling, Johan

    2014-05-01

    Tropical forests are crucial in the global carbon balance, yet information required to estimate how much carbon that enter these ecosystems through photosynthesis is very limited, in particular for Africa and for tropical montane forests. In order to increases the knowledge of natural variability of photosynthetic capacities in tropical tree species in tropical Africa, measurements of leaf traits and gas exchange were conducted on sun and shade leaves of ten tree species growing in two tropical forests in Rwanda in central Africa. Seven species were studied in Ruhande Arboretum, a forest plantation at mid altitude (1700 m), and six species in Nyungwe National Park, a cooler and higher altitude (at 2500 m) montane rainforest. Three species were common to both sites. At Nyungwe, three species each belonged to the successional groups pioneer and climax species. Climax species had considerably lower maximum rates of photosynthetic carboxylation (Vcmax) and electron transport (Jmax) than pioneer species. This difference was not related to leaf nutrient content, but rather seemed to be caused by differences in within-leaf N allocation between the two successional groups. With respect to N, leaves of climax species invested less N into photosynthetic enzymes (as judged by lower Vcmax and Jmax values) and more N into chlorophyll (as judged by higher SPAD values). Photosynthetic capacities, (i.e., Jmax and Vcmax), Jmax to Vcmax ratio and P content were significantly higher in Nyungwe than in Arboretum. Sun leaves had higher photosynthetic capacities and nutrient content than shade leaves. Across the entire dataset, variation in photosynthetic capacities among species was not related to leaf nutrient content, although significant relationships were found within individual species. This study contributes critical tropical data for global carbon models and suggests that, for montane rainforest trees of different functional types, successional group identity is a better

  2. Quantifying the response of free-ranging mammalian herbivores to the interplay between plant defense and nutrient concentrations.

    PubMed

    Bedoya-Pérez, Miguel A; Issa, Daniel D; Banks, Peter B; McArthur, Clare

    2014-08-01

    While trying to achieve their nutritional requirements, foraging herbivores face the costs of plant defenses, such as toxins. Teasing apart the costs and benefits of various chemical constituents in plants is difficult because their chemical defenses and nutrient concentrations often co-vary. We used an approach derived from predator-prey studies to quantitatively compare the foraging response of a free-ranging mammalian herbivore, the swamp wallaby (Wallabia bicolor), through three feeding trials with artificial diets that differed in their concentrations of (1) the terpene 1,8-cineole, (2) primary constituents (including nitrogen and fiber), and (3) both the terpene and the primary constituents. Applying the giving-up density (GUD) framework, we demonstrated that the foraging cost of food patches increases with higher dietary cineole concentration and decreases with higher dietary nutrient concentration. The effect of combined differences in nutrients and cineole concentrations on GUD was interactive, and high nutrient food required more cineole to achieve the same patch value as low nutrient food. Our results indicate that swamp wallabies equate low nutrient, poorly defended food with high nutrient, highly defended food, providing two contrasting diets with similar cost-benefit outcomes. This behavior suggests that equal concentrations of chemical defenses provide nutrient-poor plants with relatively greater protection as nutrient-rich plants. Nutrient-rich plants may therefore face the exacerbated problem of being preferred by herbivores and therefore need to produce more defense compounds to achieve the same level of defense as nutrient-poor plants. Our findings help explain the difference in anti-herbivore strategy of nutrient-poor and rich plants, i.e., tolerance versus defense. PMID:24924590

  3. Deep phylogeographical structure and parallel host range evolution in the leaf beetle Agelasa nigriceps.

    PubMed

    Kohyama, Tetsuo I; Matsumoto, Kazuma; Katakura, Haruo

    2014-02-01

    To understand the mechanisms behind the diversification of herbivorous insects through insect-plant interactions, it is important to know how the insects change their diet breadth in response to environmental changes. In this study, we investigated the phylogeographical pattern of the leaf beetle Agelasa nigriceps to infer the evolutionary history of its host range. While this beetle commonly uses Actinidia arguta (Actinidiaceae) as a host plant, it has been recorded recently on Pterostyrax hispidus (Styracaceae), which is now increasing in abundance at some localities in Japan due to the indirect effects of high population size of a mammalian herbivore. Considerable variation among populations in the ability of Ag. nigriceps to use P. hispidus suggests that P. hispidus is a newly acquired host plant for this beetle. Phylogenetic analyses using mitochondrial DNA sequences and amplified fragment length polymorphism (AFLP) revealed a high degree of phylogeographical structure in Ag. nigriceps throughout Japan, which is consistent with the hypothesis that several glacial refugia existed in the Japanese archipelago. In contrast, no genetic structure associated with the host plants was detected. Both the mitochondrial DNA and AFLP analyses showed that populations that can use P. hispidus are polyphyletic. These results and geographical variation in host use suggest that the host range expansion to a novel host, P. hispidus, is a very recent and possibly ongoing phenomenon and has occurred independently in several regions. Our study illustrates that the host range of herbivorous insects can evolve repeatedly in response to similar environmental changes.

  4. Varying plant density and harvest time to optimize cowpea leaf yield and nutrient content

    NASA Technical Reports Server (NTRS)

    Ohler, T. A.; Nielsen, S. S.; Mitchell, C. A.

    1996-01-01

    Plant density and harvest time were manipulated to optimize vegetative (foliar) productivity of cowpea [Vigna unguiculata (L.) Walp.] canopies for future dietary use in controlled ecological life-support systems as vegetables or salad greens. Productivity was measured as total shoot and edible dry weights (DW), edible yield rate [(EYR) grams DW per square meter per day], shoot harvest index [(SHI) grams DW per edible gram DW total shoot], and yield-efficiency rate [(YER) grams DW edible per square meter per day per grams DW nonedible]. Cowpeas were grown in a greenhouse for leaf-only harvest at 14, 28, 42, 56, 84, or 99 plants/m2 and were harvested 20, 30, 40, or 50 days after planting (DAP). Shoot and edible dry weights increased as plant density and time to harvest increased. A maximum of 1189 g shoot DW/m2 and 594 g edible DW/m2 were achieved at an estimated plant density of 85 plants/m2 and harvest 50 DAP. EYR also increased as plant density and time to harvest increased. An EYR of 11 g m-2 day-1 was predicted to occur at 86 plants/m2 and harvest 50 DAP. SHI and YER were not affected by plant density. However, the highest values of SHI (64%) and YER (1.3 g m-2 day-1 g-1) were attained when cowpeas were harvested 20 DAP. The average fat and ash contents [dry-weight basis (dwb)] of harvested leaves remained constant regardless of harvest time. Average protein content increased from 25% DW at 30 DAP to 45% DW at 50 DAP. Carbohydrate content declined from 50% DW at 30 DAP to 45% DW at 50 DAP. Total dietary fiber content (dwb) of the leaves increased from 19% to 26% as time to harvest increased from 20 to 50 days.

  5. Influence of Different Forest System Management Practices on Leaf Litter Decomposition Rates, Nutrient Dynamics and the Activity of Ligninolytic Enzymes: A Case Study from Central European Forests

    PubMed Central

    Schulz, Elke; Schloter, Michael; Buscot, François; Hofrichter, Martin; Krüger, Dirk

    2014-01-01

    Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K, Ca, P) and the activity of ligninolytic enzymes. We approached these questions using a 473 day long litterbag experiment. We found that age-class beech and spruce forests (high forest management intensity) had significantly higher decomposition rates and nutrient release (most nutrients) than unmanaged deciduous forest reserves (P<0.05). The site with near-to-nature forest management (low forest management intensity) exhibited no significant differences in litter decomposition rate, C release, lignin decomposition, and C/N, lignin/N and ligninolytic enzyme patterns compared to the unmanaged deciduous forest reserves, but most nutrient dynamics examined in this study were significantly faster under such near-to-nature forest management practices. Analyzing the activities of ligninolytic enzymes provided evidence that different forest system management practices affect litter decomposition by changing microbial enzyme activities, at least over the investigated time frame of 473 days (laccase, P<0.0001; manganese peroxidase (MnP), P = 0.0260). Our results also indicate that lignin decomposition is the rate limiting step in leaf litter decomposition and that MnP is one of the key oxidative enzymes of litter degradation. We demonstrate here that forest system management practices can significantly affect important ecological processes and services such as decomposition and nutrient cycling. PMID:24699676

  6. Influence of different forest system management practices on leaf litter decomposition rates, nutrient dynamics and the activity of ligninolytic enzymes: a case study from central European forests.

    PubMed

    Purahong, Witoon; Kapturska, Danuta; Pecyna, Marek J; Schulz, Elke; Schloter, Michael; Buscot, François; Hofrichter, Martin; Krüger, Dirk

    2014-01-01

    Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K, Ca, P) and the activity of ligninolytic enzymes. We approached these questions using a 473 day long litterbag experiment. We found that age-class beech and spruce forests (high forest management intensity) had significantly higher decomposition rates and nutrient release (most nutrients) than unmanaged deciduous forest reserves (P<0.05). The site with near-to-nature forest management (low forest management intensity) exhibited no significant differences in litter decomposition rate, C release, lignin decomposition, and C/N, lignin/N and ligninolytic enzyme patterns compared to the unmanaged deciduous forest reserves, but most nutrient dynamics examined in this study were significantly faster under such near-to-nature forest management practices. Analyzing the activities of ligninolytic enzymes provided evidence that different forest system management practices affect litter decomposition by changing microbial enzyme activities, at least over the investigated time frame of 473 days (laccase, P<0.0001; manganese peroxidase (MnP), P = 0.0260). Our results also indicate that lignin decomposition is the rate limiting step in leaf litter decomposition and that MnP is one of the key oxidative enzymes of litter degradation. We demonstrate here that forest system management practices can significantly affect important ecological processes and services such as decomposition and nutrient cycling.

  7. Can nutrient limitations explain low and declining white spruce growth near the Arctic treeline in the eastern Brooks Range, Alaska?

    NASA Astrophysics Data System (ADS)

    Ellison, S.; Sullivan, P. F.

    2014-12-01

    The position of the Arctic treeline is of critical importance for global carbon cycling and surface energy budgets. However, controls on tree growth at treeline remain uncertain. In the Alaskan Brooks Range, 20th century warming has caused varying growth responses among treeline trees, with trees in the west responding positively, while trees in the east have responded negatively. The prevailing explanation of this trend ascribes the negative growth response to warming-induced drought stress in the eastern Brooks Range. However, recent measurements of carbon isotope discrimination in tree rings, xylem sap flow and needle gas exchange suggest that drought stress cannot explain these regional growth declines. Additionally, evidence from the western Brooks Range suggests that nutrient availability, rather than drought stress, may be the proximate control on tree growth. In this study, we investigated the hypothesis that low and declining growth of eastern Brooks Range trees is due to low and declining soil nutrient availability, which may continue to decrease with climate change as soils become drier and microbial activity declines. We compared microclimate, tree performance, and a wide range of proxies for soil nutrient availability in four watersheds along a west-east transect in the Brooks Range during the growing seasons of 2013 and 2014. We hypothesized that soil nutrient availability would track closely with the strong west-east precipitation gradient, with higher rainfall and greater soil nutrient availability in the western Brooks Range. We expected to find that soil water contents in the west are near optimum for nitrogen mineralization, while those in the east are below optimum. Needle nitrogen concentration, net photosynthesis, branch extension growth, and growth in the main stem are expected to decline with the hypothesized decrease in soil nutrient availability. The results of our study will elucidate the current controls on growth of trees near the

  8. TERRESTRIAL AND MARINE SOURCES OF NUTRIENTS TO STREAMS IN THE OREGON COAST RANGE

    EPA Science Inventory

    Research on nutrient delivery to Pacific Northwest streams generally focuses on watershed processes and land use, but anadromous fish also can serve as a significant source of nutrients and energy to the streams where they return and die. To understand the relative importance of...

  9. Shelters of leaf-tying herbivores decompose faster than leaves damaged by free-living insects: Implications for nutrient turnover in polluted habitats.

    PubMed

    Kozlov, Mikhail V; Zverev, Vitali; Zvereva, Elena L

    2016-10-15

    Leaf-eating insects can influence decomposition processes by modifying quality of leaf litter, and this impact can be especially pronounced in habitats where leaf-eating insects reach high densities, for example in heavily polluted areas. We hypothesized that the decomposition rate is faster for shelters of leaf-tying larvae than for leaves damaged by free-living insects, in particular due to the accumulation of larval frass within shelters. We exposed litter bags containing samples of three different compositions (shelters built by moth larvae, leaves damaged by free-living insects and intact leaves of mountain birch, Betula pubescens ssp. czerepanovii) for one year at two heavily polluted sites near the nickel-copper smelter at Monchegorsk in north-western Russia and at two unpolluted sites. The decomposition rate of leaves damaged by free-living insects was 91% of that of undamaged leaves, whereas the mass loss of leaves composing shelters did not differ of that of undamaged leaves. These differences between leaves damaged by different guilds of herbivorous insects were uniform across the study sites, although the decomposition rate in polluted sites was reduced to 77% of that in unpolluted sites. Addition of larval frass to undamaged leaves had no effect on the subsequent decomposition rate. Therefore we suggest that damaged leaves tied by shelter-building larvae decompose faster than untied damaged leaves due to a looser physical structure of the litter, which creates favourable conditions for detritivores and soil decomposers. Thus, while leaf damage by insects per se reduces litter quality and its decomposition rate, structuring of litter by leaf-tying insects counterbalances these negative effects. We conclude that leaf-tying larvae, in contrast to free-living defoliators, do not impose negative effects on nutrient turnover rate even at their high densities, which are frequently observed in heavily polluted sites. PMID:27288287

  10. Shelters of leaf-tying herbivores decompose faster than leaves damaged by free-living insects: Implications for nutrient turnover in polluted habitats.

    PubMed

    Kozlov, Mikhail V; Zverev, Vitali; Zvereva, Elena L

    2016-10-15

    Leaf-eating insects can influence decomposition processes by modifying quality of leaf litter, and this impact can be especially pronounced in habitats where leaf-eating insects reach high densities, for example in heavily polluted areas. We hypothesized that the decomposition rate is faster for shelters of leaf-tying larvae than for leaves damaged by free-living insects, in particular due to the accumulation of larval frass within shelters. We exposed litter bags containing samples of three different compositions (shelters built by moth larvae, leaves damaged by free-living insects and intact leaves of mountain birch, Betula pubescens ssp. czerepanovii) for one year at two heavily polluted sites near the nickel-copper smelter at Monchegorsk in north-western Russia and at two unpolluted sites. The decomposition rate of leaves damaged by free-living insects was 91% of that of undamaged leaves, whereas the mass loss of leaves composing shelters did not differ of that of undamaged leaves. These differences between leaves damaged by different guilds of herbivorous insects were uniform across the study sites, although the decomposition rate in polluted sites was reduced to 77% of that in unpolluted sites. Addition of larval frass to undamaged leaves had no effect on the subsequent decomposition rate. Therefore we suggest that damaged leaves tied by shelter-building larvae decompose faster than untied damaged leaves due to a looser physical structure of the litter, which creates favourable conditions for detritivores and soil decomposers. Thus, while leaf damage by insects per se reduces litter quality and its decomposition rate, structuring of litter by leaf-tying insects counterbalances these negative effects. We conclude that leaf-tying larvae, in contrast to free-living defoliators, do not impose negative effects on nutrient turnover rate even at their high densities, which are frequently observed in heavily polluted sites.

  11. Plasticity as a plastic response: how submergence-induced leaf elongation in Rumex palustris depends on light and nutrient availability in its early life stage.

    PubMed

    Huber, Heidrun; Chen, Xin; Hendriks, Marloes; Keijsers, Danny; Voesenek, Laurentius A C J; Pierik, Ronald; Poorter, Hendrik; de Kroon, Hans; Visser, Eric J W

    2012-04-01

    Plants may experience different environmental cues throughout their development which interact in determining their phenotype. This paper tests the hypothesis that environmental conditions experienced early during ontogeny affect the phenotypic response to subsequent environmental cues. This hypothesis was tested by exposing different accessions of Rumex palustris to different light and nutrient conditions, followed by subsequent complete submergence. Final leaf length and submergence-induced plasticity were affected by the environmental conditions experienced at early developmental stages. In developmentally older leaves, submergence-induced elongation was lower in plants previously subjected to high-light conditions. Submergence-induced elongation of developmentally younger leaves, however, was larger when pregrown in high light. High-light and low-nutrient conditions led to an increase of nonstructural carbohydrates in the plants. There was a positive correlation between submergence-induced leaf elongation and carbohydrate concentration and content in roots and shoots, but not with root and shoot biomass before submergence. These results show that conditions experienced by young plants modulate the responses to subsequent environmental conditions, in both magnitude and direction. Internal resource status interacts with cues perceived at different developmental stages in determining plastic responses to the environment.

  12. Production of Short-Rotation Woody Crops Grown with a Range of Nutrient and Water Availability: Establishment Report and First-Year Responses

    SciTech Connect

    D.R. Coyle; J. Blake; K. Britton; M. Buford; R.G. Campbell; J. Cox; B. Cregg; D. Daniels; M. Jacobson; K. Johnsen; T. McDonald; K. McLeod; E. Nelson; D. Robison; R. Rummer; F. Sanchez; J. Stanturf; B. Stokes; C. Trettin; J. Tuskan; L. Wright; S. Wullschleger

    2003-12-31

    Coleman, M.D., et. al. 2003. Production of Short-Rotation Woody Crops Grown with a Range of Nutrient and Water Availability: Establishment Report and First-Year Responses. Report. USDA Forest Service, Savannah River, Aiken, SC. 26 pp. Abstract: Many researchers have studied the productivity potential of intensively managed forest plantations. However, we need to learn more about the effects of fundamental growth processes on forest productivity; especially the influence of aboveground and belowground resource acquisition and allocation. This report presents installation, establishment, and first-year results of four tree species (two cottonwood clones, sycamore, sweetgum, and loblolly pine) grown with fertilizer and irrigation treatments. At this early stage of development, irrigation and fertilization were additive only in cottonwood clone ST66 and sweetgum. Leaf area development was directly related to stem growth, but root production was not always consistent with shoot responses, suggesting that allocation of resources varies among treatments. We will evaluate the consequences of these early responses on resource availability in subsequent growing seasons. This information will be used to: (1) optimize fiber and bioenergy production; (2) understand carbon sequestration; and (3) develop innovative applications such as phytoremediation; municipal, industrial, and agricultural wastes management; and protection of soil, air, and water resources.

  13. Astrotischeria neotropicana sp. nov.-a leaf-miner on Sida, Malvaceae, currently with the broadest distribution range in the Neotropics (Lepidoptera, Tischeriidae).

    PubMed

    Diškus, Arūnas; Stonis, Jonas R

    2015-11-05

    This paper describes Astrotischeria neotropicana Diškus & Stonis, sp. nov. (Lepidoptera: Tischeriidae), a new leaf-miner on Sida (Malvaceae) with a broad distribution range in tropical Central & South America. The new species is currently recorded from the Amazon Basin in Peru and Ecuador to tropical lowlands in Guatemala and Belize (including the Caribbean Archipelago). The new species is illustrated with photographs of the adults, male and female genitalia, and the leaf-mines; distribution map is also provided.

  14. Detrital stoichiometry as a critical nexus for the effects of streamwater nutrients on leaf litter breakdown rates.

    PubMed

    Manning, David W P; Rosemond, Amy D; Kominoski, John S; Gulis, Vladislav; Benstead, Jonathan P; Maerz, John C

    2015-08-01

    Nitrogen (N) and phosphorus (P) concentrations are elevated in many freshwater systems, stimulating breakdown rates of terrestrially derived plant litter; however, the relative importance of N and P in driving litter breakdown via microbial and detritivore processing are not fully understood. Here, we determined breakdown rates of two litter species, Acer rubrum (maple) and Rhododendron maximum (rhododendron), before (PRE) and during two years (YR1, YR2) of experimental N and P additions to five streams, and quantified the relative importance of hypothesized factors contributing to breakdown. Treatment streams received a gradient of P additions (low to high soluble reactive phosphorus [SRP]; ~10-85 µg/L) crossed with a gradient of N additions (high to low dissolved inorganic nitrogen [DIN]; ~472-96 µg/L) to achieve target molar N:P ratios ranging from 128 to 2. Litter breakdown rates increased above pre-treatment levels by an average of 1.1-2.2x for maple, and 2.7-4.9x for rhododendron in YR1 and YR2. We used path analysis to compare fungal biomass, shredder biomass, litter stoichiometry (nutrient content as C:N or C:P), discharge, and streamwater temperature as predictors of breakdown rates and compared models containing streamwater N, P or N + P and litter C:N or C:P using model selection criteria. Litter breakdown rates were predicted equally with either streamwater N or P (R2 = 0.57). In models with N or P, fungal biomass, litter stoichiometry, discharge, and shredder biomass predicted breakdown rates; litter stoichiometry and fungal biomass were most important for model fit. However, N and P effects may have occurred via subtly different pathways. Litter N content increased with fungal biomass (N-driven effects) and litter P content increased with streamwater P availability (P-driven effects), presumably via P storage in fungal biomass. In either case, the effects of N and P through these pathways were associated with higher shredder biomass and breakdown

  15. Leaf gas exchange and nutrient use efficiency help explain the distribution of two Neotropical mangroves under contrasting flooding and salinity

    USGS Publications Warehouse

    Cardona-Olarte, Pablo; Krauss, Ken W.; Twilley, Robert R.

    2013-01-01

    Rhizophora mangle and Laguncularia racemosa co-occur along many intertidal floodplains in the Neotropics. Their patterns of dominance shift along various gradients, coincident with salinity, soil fertility, and tidal flooding. We used leaf gas exchange metrics to investigate the strategies of these two species in mixed culture to simulate competition under different salinity concentrations and hydroperiods. Semidiurnal tidal and permanent flooding hydroperiods at two constant salinity regimes (10 g L−1 and 40 g L−1) were simulated over 10 months. Assimilation (A), stomatal conductance (gw), intercellular CO2 concentration (Ci), instantaneous photosynthetic water use efficiency (PWUE), and photosynthetic nitrogen use efficiency (PNUE) were determined at the leaf level for both species over two time periods. Rhizophora mangle had significantly higher PWUE than did L. racemosa seedlings at low salinities; however, L. racemosa had higher PNUE and stomatal conductance and gw, accordingly, had greater intercellular CO2 (calculated) during measurements. Both species maintained similar capacities for assimilation at 10 and 40 g L−1 salinity and during both permanent and tidal hydroperiod treatments. Hydroperiod alone had no detectable effect on leaf gas exchange. However, PWUE increased and PNUE decreased for both species at 40 g L−1 salinity compared to 10 g L−1. At 40 g L−1 salinity, PNUE was higher for L. racemosa than R. mangle with tidal flooding. These treatments indicated that salinity influences gas exchange efficiency, might affect how gases are apportioned intercellularly, and accentuates different strategies for distributing leaf nitrogen to photosynthesis for these two species while growing competitively.

  16. Higher peroxidase activity, leaf nutrient contents and carbon isotope composition changes in Arabidopsis thaliana are related to rutin stress.

    PubMed

    Hussain, M Iftikhar; Reigosa, Manuel J

    2014-09-15

    Rutin, a plant secondary metabolite that is used in cosmetics and food additive and has known medicinal properties, protects plants from UV-B radiation and diseases. Rutin has been suggested to have potential in weed management, but its mode of action at physiological level is unknown. Here, we report the biochemical, physiological and oxidative response of Arabidopsis thaliana to rutin at micromolar concentrations. It was found that fresh weight; leaf mineral contents (nitrogen, sodium, potassium, copper and aluminum) were decreased following 1 week exposure to rutin. Arabidopsis roots generate significant amounts of reactive oxygen species after rutin treatment, consequently increasing membrane lipid peroxidation, decreasing leaf Ca(2+), Mg(2+), Zn(2+), Fe(2+) contents and losing root viability. Carbon isotope composition in A. thaliana leaves was less negative after rutin application than the control. Carbon isotope discrimination values were decreased following rutin treatment, with the highest reduction compared to the control at 750μM rutin. Rutin also inhibited the ratio of CO2 from leaf to air (ci/ca) at all concentrations. Total protein contents in A. thaliana leaves were decreased following rutin treatment. It was concluded carbon isotope discrimination coincided with protein degradation, increase lipid peroxidation and a decrease in ci/ca values may be the primary action site of rutin. The present results suggest that rutin possesses allelopathic potential and could be used as a candidate to develop environment friendly natural herbicide.

  17. Nutrient concentrations in Upper and Lower Echo, Fallen Leaf, Spooner, and Marlette Lakes and associated outlet streams, California and Nevada, 2002-03

    USGS Publications Warehouse

    Lico, Michael S.

    2004-01-01

    Five lakes and their outlet streams in the Lake Tahoe Basin were sampled for nutrients during 2002-03. The lakes and streams sampled included Upper Echo, Lower Echo, Fallen Leaf, Spooner, and Marlette Lakes and Echo, Taylor, and Marlette Creeks. Water samples were collected to determine seasonal and spatial concentrations of dissolved nitrite plus nitrate, dissolved ammonia, total Kjeldahl nitrogen, dissolved orthophosphate, total phosphorus, and total bioreactive iron. These data will be used by Tahoe Regional Planning Agency in revising threshold values for waters within the Lake Tahoe Basin. Standard U.S. Geological Survey methods of sample collection and analysis were used and are detailed herein. Data collected during this study and summary statistics are presented in graphical and tabular form.

  18. A functional characterisation of a wide range of cover crop species: growth and nitrogen acquisition rates, leaf traits and ecological strategies.

    PubMed

    Tribouillois, Hélène; Fort, Florian; Cruz, Pablo; Charles, Raphaël; Flores, Olivier; Garnier, Eric; Justes, Eric

    2015-01-01

    Cover crops can produce ecosystem services during the fallow period, as reducing nitrate leaching and producing green manure. Crop growth rate (CGR) and crop nitrogen acquisition rate (CNR) can be used as two indicators of the ability of cover crops to produce these services in agrosystems. We used leaf functional traits to characterise the growth strategies of 36 cover crops as an approach to assess their ability to grow and acquire N rapidly. We measured specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf area (LA) and we evaluated their relevance to characterise CGR and CNR. Cover crop species were positioned along the Leaf Economics Spectrum (LES), the SLA-LDMC plane, and the CSR triangle of plant strategies. LA was positively correlated with CGR and CNR, while LDMC was negatively correlated with CNR. All cover crops could be classified as resource-acquisitive species from their relative position on the LES and the SLA-LDMC plane. Most cover crops were located along the Competition/Ruderality axis in the CSR triangle. In particular, Brassicaceae species were classified as very competitive, which was consistent with their high CGR and CNR. Leaf functional traits, especially LA and LDMC, allowed to differentiate some cover crops strategies related to their ability to grow and acquire N. LDMC was lower and LNC was higher in cover crop than in wild species, pointing to an efficient acquisitive syndrome in the former, corresponding to the high resource availability found in agrosystems. Combining several leaf traits explained approximately half of the CGR and CNR variances, which might be considered insufficient to precisely characterise and rank cover crop species for agronomic purposes. We hypothesised that may be the consequence of domestication process, which has reduced the range of plant strategies and modified the leaf trait syndrome in cultivated species. PMID:25789485

  19. A functional characterisation of a wide range of cover crop species: growth and nitrogen acquisition rates, leaf traits and ecological strategies.

    PubMed

    Tribouillois, Hélène; Fort, Florian; Cruz, Pablo; Charles, Raphaël; Flores, Olivier; Garnier, Eric; Justes, Eric

    2015-01-01

    Cover crops can produce ecosystem services during the fallow period, as reducing nitrate leaching and producing green manure. Crop growth rate (CGR) and crop nitrogen acquisition rate (CNR) can be used as two indicators of the ability of cover crops to produce these services in agrosystems. We used leaf functional traits to characterise the growth strategies of 36 cover crops as an approach to assess their ability to grow and acquire N rapidly. We measured specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf area (LA) and we evaluated their relevance to characterise CGR and CNR. Cover crop species were positioned along the Leaf Economics Spectrum (LES), the SLA-LDMC plane, and the CSR triangle of plant strategies. LA was positively correlated with CGR and CNR, while LDMC was negatively correlated with CNR. All cover crops could be classified as resource-acquisitive species from their relative position on the LES and the SLA-LDMC plane. Most cover crops were located along the Competition/Ruderality axis in the CSR triangle. In particular, Brassicaceae species were classified as very competitive, which was consistent with their high CGR and CNR. Leaf functional traits, especially LA and LDMC, allowed to differentiate some cover crops strategies related to their ability to grow and acquire N. LDMC was lower and LNC was higher in cover crop than in wild species, pointing to an efficient acquisitive syndrome in the former, corresponding to the high resource availability found in agrosystems. Combining several leaf traits explained approximately half of the CGR and CNR variances, which might be considered insufficient to precisely characterise and rank cover crop species for agronomic purposes. We hypothesised that may be the consequence of domestication process, which has reduced the range of plant strategies and modified the leaf trait syndrome in cultivated species.

  20. A Functional Characterisation of a Wide Range of Cover Crop Species: Growth and Nitrogen Acquisition Rates, Leaf Traits and Ecological Strategies

    PubMed Central

    Tribouillois, Hélène; Fort, Florian; Cruz, Pablo; Charles, Raphaël; Flores, Olivier; Garnier, Eric; Justes, Eric

    2015-01-01

    Cover crops can produce ecosystem services during the fallow period, as reducing nitrate leaching and producing green manure. Crop growth rate (CGR) and crop nitrogen acquisition rate (CNR) can be used as two indicators of the ability of cover crops to produce these services in agrosystems. We used leaf functional traits to characterise the growth strategies of 36 cover crops as an approach to assess their ability to grow and acquire N rapidly. We measured specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf area (LA) and we evaluated their relevance to characterise CGR and CNR. Cover crop species were positioned along the Leaf Economics Spectrum (LES), the SLA-LDMC plane, and the CSR triangle of plant strategies. LA was positively correlated with CGR and CNR, while LDMC was negatively correlated with CNR. All cover crops could be classified as resource-acquisitive species from their relative position on the LES and the SLA-LDMC plane. Most cover crops were located along the Competition/Ruderality axis in the CSR triangle. In particular, Brassicaceae species were classified as very competitive, which was consistent with their high CGR and CNR. Leaf functional traits, especially LA and LDMC, allowed to differentiate some cover crops strategies related to their ability to grow and acquire N. LDMC was lower and LNC was higher in cover crop than in wild species, pointing to an efficient acquisitive syndrome in the former, corresponding to the high resource availability found in agrosystems. Combining several leaf traits explained approximately half of the CGR and CNR variances, which might be considered insufficient to precisely characterise and rank cover crop species for agronomic purposes. We hypothesised that may be the consequence of domestication process, which has reduced the range of plant strategies and modified the leaf trait syndrome in cultivated species. PMID:25789485

  1. Characterization of forest crops with a range of nutrient and water treatments using AISA Hyperspectral Imagery.

    SciTech Connect

    Gong, Binglei; Im, Jungho; Jensen, John, R.; Coleman, Mark; Rhee, Jinyoung; Nelson, Eric

    2012-07-01

    This research examined the utility of Airborne Imaging Spectrometer for Applications (AISA) hyperspectral imagery for estimating the biomass of three forest crops---sycamore, sweetgum and loblolly pine--planted in experimental plots with a range of fertilization and irrigation treatments on the Savannah River Site near Aiken, South Carolina.

  2. [Effects of snow cover on the decomposition and nutrient dynamics of Sibiraea angustata leaf litter in western Sichuan plateau, Southwest China].

    PubMed

    Hu, Xia; Wu, Ning; Wu, Yan; Zuo, Wan-Qing; Guo, Hai-Xia; Wang, Jin-Niu

    2012-05-01

    Soil-borne bag method was adopted to study the decomposition and nutrient dynamics of Sibiraea angustata leaf litter under different depths (0, 30 and 100 cm) of snow cover in western Sichuan plateau in January-May, 2010. In snow-free plot, the mass loss rate of the litter over the five months was 29.9%; in the plots with 30 and 100 cm snow cover, the litter mass loss rate was 33.8% and 35.2%, respectively. During the decomposition, definite N enrichment in the litter was observed, while the P enrichment fluctuated. The C content and C/N ratio of the litter decreased sharply at the early stage of decomposition, but increased gradually after then. Snow cover greatly contributed to the rapid decomposition of litter and the N enrichment in the litter, but had little effects on the litter C and P contents. In western Sichuan plateau, durable snow cover with a depth of > 30 cm could alter the litter decomposition pattern, and substantially affect the soil nutrient turnover and plant community composition.

  3. Biogeographic patterns of nutrient resorption from Quercus variabilis Blume leaves across China.

    PubMed

    Sun, X; Kang, H; Chen, H Y H; Björn, B; Samuel, B F; Liu, C

    2016-05-01

    The variation in nutrient resorption has been studied at different taxonomic levels and geographic ranges. However, the variable traits of nutrient resorption at the individual species level across its distribution are poorly understood. We examined the variability and environmental controls of leaf nutrient resorption of Quercus variabilis, a widely distributed species of important ecological and economic value in China. The mean resorption efficiency was highest for phosphorus (P), followed by potassium (K), nitrogen (N), sulphur (S), magnesium (Mg) and carbon (C). Resorption efficiencies and proficiencies were strongly affected by climate and respective nutrients concentrations in soils and green leaves, but had little association with leaf mass per area. Climate factors, especially growing season length, were dominant drivers of nutrient resorption efficiencies, except for C, which was strongly related to green leaf C status. In contrast, green leaf nutritional status was the primary controlling factor of leaf nutrient proficiencies, except for C. Resorption efficiencies of N, P, K and S increased significantly with latitude, and were negatively related to growing season length and mean annual temperature. In turn, N, P, K and S in senesced leaves decreased with latitude, likely due to their efficient resorption response to variation in climate, but increased for Mg and did not change for C. Our results indicate that the nutrient resorption efficiency and proficiency of Q. variabilis differed strongly among nutrients, as well as growing environments. Our findings provide important insights into understanding the nutrient conservation strategy at the individual species level and its possible influence on nutrient cycling.

  4. Two Measurement Methods of Leaf Dry Matter Content Produce Similar Results in a Broad Range of Species

    PubMed Central

    Vaieretti, María Victoria; Díaz, Sandra; Vile, Denis; Garnier, Eric

    2007-01-01

    Background and Aims Leaf dry matter content (LDMC) is widely used as an indicator of plant resource use in plant functional trait databases. Two main methods have been proposed to measure LDMC, which basically differ in the rehydration procedure to which leaves are subjected after harvesting. These are the ‘complete rehydration’ protocol of Garnier et al. (2001, Functional Ecology 15: 688–695) and the ‘partial rehydration’ protocol of Vendramini et al. (2002, New Phytologist 154: 147–157). Methods To test differences in LDMC due to the use of different methods, LDMC was measured on 51 native and cultivated species representing a wide range of plant families and growth forms from central-western Argentina, following the complete rehydration and partial rehydration protocols. Key Results and Conclusions The LDMC values obtained by both methods were strongly and positively correlated, clearly showing that LDMC is highly conserved between the two procedures. These trends were not altered by the exclusion of plants with non-laminar leaves. Although the complete rehydration method is the safest to measure LDMC, the partial rehydration procedure produces similar results and is faster. It therefore appears as an acceptable option for those situations in which the complete rehydration method cannot be applied. Two notes of caution are given for cases in which different datasets are compared or combined: (1) the discrepancy between the two rehydration protocols is greatest in the case of high-LDMC (succulent or tender) leaves; (2) the results suggest that, when comparing many studies across unrelated datasets, differences in the measurement protocol may be less important than differences among seasons, years and the quality of local habitats. PMID:17353207

  5. Hibernation in warm hibernacula by free-ranging Formosan leaf-nosed bats, Hipposideros terasensis, in subtropical Taiwan.

    PubMed

    Liu, Jian-Nan; Karasov, William H

    2011-01-01

    The subtropical Formosan leaf-nosed bats, Hipposideros terasensis (Hipposideridae), show little activity during winter. It has never been determined whether in winter they exhibit hibernation and multi-day periods of low body temperature. The objectives of this study were to understand the winter activity pattern of H. terasensis and to examine whether it enters hibernation during winter. We monitored the skin temperature (T (sk)) of nine free-ranging H. terasensis by attaching temperature-sensitive transmitters during the winters of 2007-2008 and 2008-2009. The results showed that H. terasensis entered hibernation from late December to early March. H. terasensis, however, differs from temperate hibernating bats in several ways: (1) it is capable of hibernation at roost temperature (T (r)) and T (sk) > 20°C; (2) hibernation at high T (r) and T (sk) does not lead to a relatively high arousal frequency; and (3) adults do not increase body mass in autumn prior to hibernation. To test the hypothesis that H. terasensis feeds frequently during the hibernation period to compensate for the high energetic demands of hibernating in warm hibernacula, we recorded the number and timing of bats that emerged from and entered into a hibernaculum, which contained more than 1,000 bats. From 30 December 2007 to 29 February 2008, an average of only 8.4 bats (<1%) per night (29 nights) emerged from the hibernaculum. Adult bats lost an average of 13-14% of body mass during an approximately 70-day hibernation period. We suggest that H. terasensis might have remarkably low torpid metabolic rates during hibernation.

  6. Auxin is a long-range signal that acts independently of ethylene signaling on leaf abscission in Populus

    PubMed Central

    Jin, Xu; Zimmermann, Jorma; Polle, Andrea; Fischer, Urs

    2015-01-01

    Timing of leaf abscission is an important trait for biomass production and seasonal acclimation in deciduous trees. The signaling leading to organ separation, from the external cue (decreasing photoperiod) to ethylene-regulated hydrolysis of the middle lamellae in the abscission zone, is only poorly understood. Data from annual species indicate that the formation of an auxin gradient spanning the abscission zone regulates the timing of abscission. We established an experimental system in Populus to induce leaf shedding synchronously under controlled greenhouse conditions in order to test the function of auxin in leaf abscission. Here, we show that exogenous auxin delayed abscission of dark-induced leaves over short and long distances and that a new auxin response maximum preceded the formation of an abscission zone. Several auxin transporters were down-regulated during abscission and inhibition of polar auxin transport delayed leaf shedding. Ethylene signaling was not involved in the regulation of these auxin transporters and in the formation of an abscission zone, but was required for the expression of hydrolytic enzymes associated with cell separation. Since exogenous auxin delayed abscission in absence of ethylene signaling auxin likely acts independently of ethylene signaling on cell separation. PMID:26322071

  7. Auxin is a long-range signal that acts independently of ethylene signaling on leaf abscission in Populus.

    PubMed

    Jin, Xu; Zimmermann, Jorma; Polle, Andrea; Fischer, Urs

    2015-01-01

    Timing of leaf abscission is an important trait for biomass production and seasonal acclimation in deciduous trees. The signaling leading to organ separation, from the external cue (decreasing photoperiod) to ethylene-regulated hydrolysis of the middle lamellae in the abscission zone, is only poorly understood. Data from annual species indicate that the formation of an auxin gradient spanning the abscission zone regulates the timing of abscission. We established an experimental system in Populus to induce leaf shedding synchronously under controlled greenhouse conditions in order to test the function of auxin in leaf abscission. Here, we show that exogenous auxin delayed abscission of dark-induced leaves over short and long distances and that a new auxin response maximum preceded the formation of an abscission zone. Several auxin transporters were down-regulated during abscission and inhibition of polar auxin transport delayed leaf shedding. Ethylene signaling was not involved in the regulation of these auxin transporters and in the formation of an abscission zone, but was required for the expression of hydrolytic enzymes associated with cell separation. Since exogenous auxin delayed abscission in absence of ethylene signaling auxin likely acts independently of ethylene signaling on cell separation.

  8. Influence of Dietary Supplementation of Condensed Tannins through Leaf Meal Mixture on Intake, Nutrient Utilization and Performance of Haemonchus contortus Infected Sheep.

    PubMed

    Pathak, A K; Dutta, Narayan; Banerjee, P S; Pattanaik, A K; Sharma, K

    2013-10-01

    The study assessed the effect of dietary supplementation of leaf meal mixture (LMM) containing condensed tannins (CT) on feed intake, nutrient utilization and performance of sheep infected with Haemonchus contortus. Eighteen adult sheep of similar age and body weight (25.03±1.52) were included in this study and out of these, 12 sheep were infected with single dose of infective third stage larvae of H. contortus at 2,000 larvae per sheep. The experimental sheep were allocated in three different groups' i.e. negative control (NC; no infection), control (C; H. contortus infected) and treatment (T; H. contortus infected+CT at 1.5% of the DM through LMM) and the experiment was conducted for a period of 90 d. The intake of dry matter (DM), organic matter (OM) and digestibility of DM, OM, neutral detergent fibre (NDF) and acid detergent fibre (ADF) were comparable among three animal groups. However, digestibility of crude protein (CP) and ether extract (EE) were significantly (p<0.05) higher in NC group as compared to both C and T groups. Nitrogen (N) retention (g/d or % of N intake) was significantly (p = 0.038) lower in C group as compared to T and NC groups. Daily intake (g/kg W(0.75)) of digestible crude protein (DCP), digestible organic matter (DOM) and total digestible nutrient (TDN) did not differ significantly (p<0.05) in the three groups. Haemoglobin (Hb) and packed cell volume (PCV) were significantly (p<0.001) higher in treatment group as compared to control. The level of Hb and PCV reduced (p<0.001) after 30 days of experimental feeding. CT significantly (p<0.001) reduced serum urea in T group as compared to NC and C groups. Serum proteins differed significantly (p<0.01) among the three groups. The activity of serum enzymes AST, ALT, ALP and LDH were also statistically non significant (p<0.05) among treatments. The weight of abomasal lymph nodes (ALN) in T group was higher (p<0.05) than in C group. Treatment group had lower (p<0.05) total worms and fecal egg

  9. Influence of Dietary Supplementation of Condensed Tannins through Leaf Meal Mixture on Intake, Nutrient Utilization and Performance of Haemonchus contortus Infected Sheep

    PubMed Central

    Pathak, A. K.; Dutta, Narayan; Banerjee, P. S.; Pattanaik, A. K.; Sharma, K.

    2013-01-01

    The study assessed the effect of dietary supplementation of leaf meal mixture (LMM) containing condensed tannins (CT) on feed intake, nutrient utilization and performance of sheep infected with Haemonchus contortus. Eighteen adult sheep of similar age and body weight (25.03±1.52) were included in this study and out of these, 12 sheep were infected with single dose of infective third stage larvae of H. contortus at 2,000 larvae per sheep. The experimental sheep were allocated in three different groups’ i.e. negative control (NC; no infection), control (C; H. contortus infected) and treatment (T; H. contortus infected+CT at 1.5% of the DM through LMM) and the experiment was conducted for a period of 90 d. The intake of dry matter (DM), organic matter (OM) and digestibility of DM, OM, neutral detergent fibre (NDF) and acid detergent fibre (ADF) were comparable among three animal groups. However, digestibility of crude protein (CP) and ether extract (EE) were significantly (p<0.05) higher in NC group as compared to both C and T groups. Nitrogen (N) retention (g/d or % of N intake) was significantly (p = 0.038) lower in C group as compared to T and NC groups. Daily intake (g/kg W0.75) of digestible crude protein (DCP), digestible organic matter (DOM) and total digestible nutrient (TDN) did not differ significantly (p<0.05) in the three groups. Haemoglobin (Hb) and packed cell volume (PCV) were significantly (p<0.001) higher in treatment group as compared to control. The level of Hb and PCV reduced (p<0.001) after 30 days of experimental feeding. CT significantly (p<0.001) reduced serum urea in T group as compared to NC and C groups. Serum proteins differed significantly (p<0.01) among the three groups. The activity of serum enzymes AST, ALT, ALP and LDH were also statistically non significant (p<0.05) among treatments. The weight of abomasal lymph nodes (ALN) in T group was higher (p<0.05) than in C group. Treatment group had lower (p<0.05) total worms and fecal egg

  10. Selenium concentrations in leaf material from Astragalus Oxyphysus (diablo locoweed) and Atriplex Lentiformis (quail bush) in the interior Coast Ranges and the western San Joaquin Valley, California

    USGS Publications Warehouse

    Izbicki, J.A.; Harms, T.F.

    1986-01-01

    Leaf material from selenium accumulating plants was collected and analyzed for selenium to obtain a relative indication of selenium concentrations in soils and identify sites suitable for further soil study. Selenium concentrations of 14 samples of leaf material from Astragalus oxyphysus ranged from 0.08 to 3.5 microg/g dry weight and had a median concentration of 0.25 microg/g. Five replicate samples of A. oxyphysus had a mean selenium concentration of 0.22 microg/g and a standard deviation of 0.07. Selenium concentrations of 17 samples of leaf material from Atriplex lentiformis ranged from 0.08 to 7.5 microg/g and had a median concentration of 0.35 microg/g. As a general guideline, the National Academy of Sciences recommends a maximum safe tolerance level of 2 microg/g of selenium in animal feeds. One sample of A. oxyphysus, collected in the Panoche Creek drainage, exceeded 2 mcirog/g. Three samples of A. lentiformis, collected in Klipstein Canyon, Tumey Fan, and Panoche Fan, equaled or exceeded 2 microg/g. These sites may be suitable. (Author 's abstract)

  11. Selenium concentrations in leaf material from Astragalus oxyphysus (Diablo Locoweed) and Atriplex lentiformis (quail bush) in the interior coast ranges and the western San Joaquin Valley, California

    SciTech Connect

    Izbicki, J.A.; Harms, T.F.

    1986-01-01

    Leaf material from selenium accumulating plants was collected and analyzed for selenium to obtain a relative indication of selenium concentrations in soils and identify sites suitable for further soil study. Selenium concentrations of 14 samples of leaf material from Astragalus oxyphysus ranged from 0.08 to 3.5 microg/g dry weight and had a median concentration of 0.25 microg/g. Five replicate samples of A. oxyphysus had a mean selenium concentration of 0.22 microg/g and a standard deviation of 0.07. Selenium concentrations of 17 samples of leaf material from Atriplex lentiformis ranged from 0.08 to 7.5 microg/g and had a median concentration of 0.35 microg/g. As a general guideline, the National Academy of Sciences recommends a maximum safe tolerance level of 2 microg/g of selenium in animal feeds. One sample of A. oxyphysus, collected in the Panoche Creek drainage, exceeded 2 microg/g. Three samples of A. lentiformis, collected in Klipstein Canyon, Tumey Fan, and Panoche Fan, equaled or exceeded 2 microg/g. These sites may be suitable. 34 refs., 5 figs., 2 tabs.

  12. Relating Stomatal Conductance to Leaf Functional Traits

    PubMed Central

    Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

    2015-01-01

    Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants’ regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES

  13. Relating Stomatal Conductance to Leaf Functional Traits.

    PubMed

    Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

    2015-10-12

    Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants' regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES.

  14. STABLE ISOTOPE STUDIES ON THE USE OF MARINE-DERIVED NUTRIENTS BY COHO SALMON JUVENILES IN THE OREGON COAST RANGE

    EPA Science Inventory

    Greatly reduced spawning runs of anadromous salmon in streams of the Pacific Northwest (USA) have led to concerns about the effects of reduced marine derived nutrients (MDN's) on sustaining over-wintering juvenile salmon in those streams. In response to these concerns, state a...

  15. Effect of tanniferous leaf meal based multi-nutrient blocks on feed intake, hematological profile, immune response, and body weight changes in Haemonchus contortus infected goats

    PubMed Central

    Singh, Surender; Pathak, A. K.; Sharma, R. K.; Khan, Muzaffer

    2015-01-01

    Aim: The aim was to assess the effect of multi nutrient block (MNB) supplementation with and without tanniferous leaf meal mixture on feed intake, hematological profile, immune response, and body weight changes of goats that were experimentally infected with Haemonchus contortus. Materials and Methods: Total 12 adult male goats of similar age and body weight (26.49±0.87) were allocated in 3 groups in completely randomized design. MNB supplemented in first two groups i.e. in T1 (no infection) and T2 (H. contortus infection @ 1500 L3/goat) group, while, MNB-condensed tannin (CT) supplemented in T3 (H. contortus infection @ 1500 L3/goat + CT source). All goats were fed concentrate mixture @ 100 g/day/goat, ad lib wheat straw and MNB or MNB-CT to meet their requirement for maintenance. Body weights were recorded and blood and fecal samples were collected at 0 day and thereafter at 15 days intervals for a period of 75 days for the assessment of body weight changes, hematological profile and H. contortus loads. Both humoral and cell-mediated immune (CMI) response were assessed at the end of feeding trial. Results: Mean hemoglobin and packed cell volume (PCV) levels were found to be highest (p<0.001, p<0.05) in T1 group followed by T3 group and lowest values were observed in T2 group. However, The PCV values between T1 and T3 groups were found to be statistically non-significant (p<0.05). The humoral and CMI response were significantly (p<0.036) higher in T3 group as compared to T2 group. MNB-CT supplementation significantly (p<0.001) reduced fecal egg counts in T3 group as compared to MNB supplemented T2 group. Conclusion: Supplementation of MNB-CT could be used as an alternative sustainable method to control H. contortus and maintained health status and performance of goats in face of parasitic challenge. PMID:27047137

  16. Growth performance, nutrient utilization, and feed efficiency in broilers fed Tithonia diversifolia leaf meal as substitute of conventional feed ingredients in Mizoram

    PubMed Central

    Buragohain, Rajat

    2016-01-01

    Aim: The study was for assessment of growth performance, nutrient utilization, and feed efficiency in broilers fed rations with varying levels of Tithonia diversifolia leaf meal (TDLM) as a substitute of conventional feed ingredients in Mizoram. Materials and Methods: A total of 180, 1-day-old broiler chicks were randomly divided into six homogeneous groups and fed rations incorporated with TDLM (TDLM at 0% [TDLM-0], 2% [TDLM-2], 4% [TDLM-4], 6% [TDLM-6], 8% [TDLM-8], and 10% [TDLM-10] level as substitute of conventional feed ingredients) for 6 weeks. The chicks were reared in battery brooders for the first 2 weeks, and thereafter, in well-ventilated deep litter house following standard management protocols. Feed and drinking water were provided ad libitum to all the groups throughout the experiment. The daily feed intake and weekly body weight gain were recorded, and a metabolic trial for 3 days was conducted at the end of the 6th week. Results: Feed consumption decreased for inclusion of TDLM but without any significant differences, except during the 3rd week where it reduced significantly (p<0.05) at and above 6% TDLM in the ration. The average body weight gain decreased significantly (p<0.05) above 6% TDLM inclusion. The average body weights at 7th, 14th, and 21st day of age reduced significantly (p<0.05) from 4% to 10% TDLM inclusion level but was statistically non-significant up to 4% TDLM at 28th, 35th, and 42nd day of age. Body weight at 42nd day of age was 1624.72±30.52, 1616.66±17.84, 1592.60±19.24, 1404.61±17.76, 1188.29±17.67, and 1054.33±18.81 gin TDLM-0, TDLM-2, TDLM-4, TDLM-6, TDLM-8, and TDLM-10, respectively. The digestibility of nutrients decreased with increased inclusion level of TDLM. The digestibility coefficient of dry matter, crude protein, ether extract, and nitrogen free extract were significantly higher in TDLM-0, but crude fiber digestibility was comparable without any significant difference among the groups. Feed conversion ratio

  17. Measuring feeding traits of a range of litter-consuming terrestrial snails: leaf litter consumption, faeces production and scaling with body size.

    PubMed

    Astor, Tina; Lenoir, Lisette; Berg, Matty P

    2015-07-01

    Plant litter decomposition is an essential ecosystem function that contributes to energy and nutrient cycling above- and belowground. Terrestrial gastropods can affect this process in various ways: they consume and fragment leaf litter and create suitable habitats for microorganisms through the production of faeces and mucus. We assessed the contributions of ten litter-feeding terrestrial snail species to leaf litter mass loss and checked whether consumption rate and faeces production scale with body size (i.e. shell size and shape), which may indicate that morphological traits can serve as proxies for consumption rate. Additionally, we compared the consumption rates of a subset of these species among litter types of two plant species which differ in resource quality (Fraxinus excelsior and Betula pendula). These snail species differed in their litter consumption rates. Consumption rates differed between the two litter types, whereas the rank order of litter consumption by the different species was independent of litter quality. Consumption rate and faeces production were positively related to shell size, whereas relative consumption rate and faeces production were related to shell shape, with more elongated snail species having lower relative consumption rates and faeces production rates. Our results show that easily measurable morphological traits scale with the feeding traits of snails, and represent useful proxies for consumption rate and faeces production, which are laborious to measure. Thus, estimated potential total consumption rates of snail communities along environmental gradients may be inferred from shell-size distributions. Our study contributes to a systematic trait-based evaluation of the importance of gastropods to litter decomposition.

  18. The effects of leaf area density variation on the collection efficiency of black carbon in the size range of ultrafine particles (UFP)

    NASA Astrophysics Data System (ADS)

    Huang, C.; Lin, M.; Khlystov, A.; Katul, G. G.

    2012-12-01

    Black carbon is mainly produced in the ultra-fine particle (UFP) size range of 10-100 nm from combustion processes and is now receiving significant attention given its role in global and regional climate change, cloud physics, human health and respiratory related diseases. Likewise, the role of vegetated surfaces in removing UFP is drawing increased attention, prompting interest in the relationship between leaf area density and UFP collection efficiency. Here, carbonaceous particles, mainly black carbon, were generated by burning candles during "sooting burn" to explore the effects of leaf area density (LAD) variation on the collection efficiency of black carbon in the UFP size range. Three scenarios were explored in a wind tunnel: (1) Juniperus Chinensis branches that are uniformly distributed within the test section; (2) LAD that is linearly increasing with downwind distance and (3) LAD that is decreasing with downwind distance. The total leaf area index (LAI) was maintained constant in all three cases. Particle concentrations were measured at multiple locations within the vegetated volume for a range of sizes of UFP (12.6-102 nm) using Scanning Mobility Particle Sizer (SMPS). The measured concentration can be used to evaluate the performance of a size-resolving model that couples the turbulent flow field and the collection efficiency for the variable LAD. The model assumes that (i) the mean longitudinal momentum balance is controlled only by the interplay between drag force and the pressure gradient, and (ii) the dominant collection mechanism for UFP is Brownian diffusion. Hence, other collection mechanisms such as inertial impaction, interception and phoretic effects are negligible. Good agreement was found between the model calculations of the UFP collection efficiency by the vegetation and the wind tunnel measurements for all three cases and across a wide range of wind speeds and particle size. It was shown that variations in leaf area density lead to a

  19. Predicting leaf traits of herbaceous species from their spectral characteristics

    PubMed Central

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-01-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait–spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m2 leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties. PMID:24683454

  20. Biogeographic patterns of nutrient resorption from Quercus variabilis Blume leaves across China.

    PubMed

    Sun, X; Kang, H; Chen, H Y H; Björn, B; Samuel, B F; Liu, C

    2016-05-01

    The variation in nutrient resorption has been studied at different taxonomic levels and geographic ranges. However, the variable traits of nutrient resorption at the individual species level across its distribution are poorly understood. We examined the variability and environmental controls of leaf nutrient resorption of Quercus variabilis, a widely distributed species of important ecological and economic value in China. The mean resorption efficiency was highest for phosphorus (P), followed by potassium (K), nitrogen (N), sulphur (S), magnesium (Mg) and carbon (C). Resorption efficiencies and proficiencies were strongly affected by climate and respective nutrients concentrations in soils and green leaves, but had little association with leaf mass per area. Climate factors, especially growing season length, were dominant drivers of nutrient resorption efficiencies, except for C, which was strongly related to green leaf C status. In contrast, green leaf nutritional status was the primary controlling factor of leaf nutrient proficiencies, except for C. Resorption efficiencies of N, P, K and S increased significantly with latitude, and were negatively related to growing season length and mean annual temperature. In turn, N, P, K and S in senesced leaves decreased with latitude, likely due to their efficient resorption response to variation in climate, but increased for Mg and did not change for C. Our results indicate that the nutrient resorption efficiency and proficiency of Q. variabilis differed strongly among nutrients, as well as growing environments. Our findings provide important insights into understanding the nutrient conservation strategy at the individual species level and its possible influence on nutrient cycling. PMID:26597338

  1. LANDSCAPE CHARACTERISTICS AND HIGH STREAM NITROGEN IN THE OREGON COAST RANGE: RED ALDER COMPLICATES USE OF NUTRIENT CRITERIA

    EPA Science Inventory

    Stream nitrogen concentrations are variable and often high in the Oregon Coast Range, uncharacteristic for a predominantly forested region. We compiled stream nitrogen data and GIS-derived landscape characteristics in order to examine variation in nitrogen across the region. In s...

  2. Linking Landscape Characteristics and High Stream Nitrogen in the Oregon Coast Range: Red Alder Complicates Use of Nutrient Criteria

    EPA Science Inventory

    Red alder (a nitrogen-fixing tree) and sea salt inputs can strongly influence stream nitrogen concentrations in western Oregon and Washington. We compiled a database of stream nitrogen and landscape characteristics in the Oregon Coast Range. Basal area of alder, expressed as a ...

  3. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical concentration.

    PubMed

    Singh, Shardendu K; Reddy, Vangimalla R

    2015-10-01

    To evaluate the response of CO2 assimilation rate (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition, soybean plants were grown in controlled environment with sufficient (0.50mM) and deficient (0.10 and 0.01 mM) phosphate (P) supply under ambient and elevated CO2 (aCO2, 400 and eCO2, 800 μmol mol(-1), respectively). Measurements were made at ambient (21%) and low (2%) O2 concentrations. Results showed strong correlation of leaf P concentration with PN and CF parameters. The P deficiency showed parallel decreases in PN, and CF parameters including quantum efficiency (Fv'/Fm'), quantum yield of photosystem II (ΦPSII), electron transport rate (JF), and photochemical quenching (qP). The Fv'/Fm' decreased as a result of greater decline in maximal (Fm') than minimal (Fo') fluorescence. The eCO2 stimulated PN especially under higher leaf P concentrations. Low O2 also stimulated PN but only at aCO2. The photosynthetic carbon reduction (PCR, signified by PN) and photorespiratory carbon oxidation cycles (PCO, signified photorespiration as indicated by ratio of JF to gross PN and % increase in PN at 2% O2) was the major electron sinks. However, the presence of alternative electron sink was also evident as determined by the difference between the electron transport calculated from chlorophyll fluorescence and gas exchange measurements. Alternative electron sink declined at lower leaf P concentration suggesting its minor role in photochemical energy consumption, thus dissipation of the excess excitation pressure of PSII reaction center under P deficiency. The JF/PG and % increase in PN at 2 versus 21% O2 remained consistent across leaf P concentration suggesting PCO cycle as an important mechanism to dissipate excess excitation energy in P deficient leaves. The severe decline of Fv'/Fm', ΦPSII, JF and qP under P deficiency also suggested the occurrences of excess radiant energy dissipation by non-photochemical quenching mechanisms. Critical

  4. Response of carbon assimilation and chlorophyll fluorescence to soybean leaf phosphorus across CO2: Alternative electron sink, nutrient efficiency and critical concentration.

    PubMed

    Singh, Shardendu K; Reddy, Vangimalla R

    2015-10-01

    To evaluate the response of CO2 assimilation rate (PN) and various chlorophyll fluorescence (CF) parameters to phosphorus (P) nutrition, soybean plants were grown in controlled environment with sufficient (0.50mM) and deficient (0.10 and 0.01 mM) phosphate (P) supply under ambient and elevated CO2 (aCO2, 400 and eCO2, 800 μmol mol(-1), respectively). Measurements were made at ambient (21%) and low (2%) O2 concentrations. Results showed strong correlation of leaf P concentration with PN and CF parameters. The P deficiency showed parallel decreases in PN, and CF parameters including quantum efficiency (Fv'/Fm'), quantum yield of photosystem II (ΦPSII), electron transport rate (JF), and photochemical quenching (qP). The Fv'/Fm' decreased as a result of greater decline in maximal (Fm') than minimal (Fo') fluorescence. The eCO2 stimulated PN especially under higher leaf P concentrations. Low O2 also stimulated PN but only at aCO2. The photosynthetic carbon reduction (PCR, signified by PN) and photorespiratory carbon oxidation cycles (PCO, signified photorespiration as indicated by ratio of JF to gross PN and % increase in PN at 2% O2) was the major electron sinks. However, the presence of alternative electron sink was also evident as determined by the difference between the electron transport calculated from chlorophyll fluorescence and gas exchange measurements. Alternative electron sink declined at lower leaf P concentration suggesting its minor role in photochemical energy consumption, thus dissipation of the excess excitation pressure of PSII reaction center under P deficiency. The JF/PG and % increase in PN at 2 versus 21% O2 remained consistent across leaf P concentration suggesting PCO cycle as an important mechanism to dissipate excess excitation energy in P deficient leaves. The severe decline of Fv'/Fm', ΦPSII, JF and qP under P deficiency also suggested the occurrences of excess radiant energy dissipation by non-photochemical quenching mechanisms. Critical

  5. Novel evidence for within-species leaf economics spectrum at multiple spatial scales

    PubMed Central

    Hu, Yu-Kun; Pan, Xu; Liu, Guo-Fang; Li, Wen-Bing; Dai, Wen-Hong; Tang, Shuang-Li; Zhang, Ya-Lin; Xiao, Tao; Chen, Ling-Yun; Xiong, Wei; Zhou, Meng-Yao; Song, Yao-Bin; Dong, Ming

    2015-01-01

    Leaf economics spectrum (LES), characterizing covariation among a suite of leaf traits relevant to carbon and nutrient economics, has been examined largely among species but hardly within species. In addition, very little attempt has been made to examine whether the existence of LES depends on spatial scales. To address these questions, we quantified the variation and covariation of four leaf economic traits (specific leaf area, leaf dry matter content, leaf nitrogen and phosphorus contents) in a cosmopolitan wetland species (Phragmites australis) at three spatial (inter-regional, regional, and site) scales across most of the species range in China. The species expressed large intraspecific variation in the leaf economic traits at all of the three spatial scales. It also showed strong covariation among the four leaf economic traits across the species range. The coordination among leaf economic traits resulted in LES at all three scales and the environmental variables determining variation in leaf economic traits were different among the spatial scales. Our results provide novel evidence for within-species LES at multiple spatial scales, indicating that resource trade-off could also constrain intraspecific trait variation mainly driven by climatic and/or edaphic differences. PMID:26579151

  6. Novel evidence for within-species leaf economics spectrum at multiple spatial scales.

    PubMed

    Hu, Yu-Kun; Pan, Xu; Liu, Guo-Fang; Li, Wen-Bing; Dai, Wen-Hong; Tang, Shuang-Li; Zhang, Ya-Lin; Xiao, Tao; Chen, Ling-Yun; Xiong, Wei; Zhou, Meng-Yao; Song, Yao-Bin; Dong, Ming

    2015-01-01

    Leaf economics spectrum (LES), characterizing covariation among a suite of leaf traits relevant to carbon and nutrient economics, has been examined largely among species but hardly within species. In addition, very little attempt has been made to examine whether the existence of LES depends on spatial scales. To address these questions, we quantified the variation and covariation of four leaf economic traits (specific leaf area, leaf dry matter content, leaf nitrogen and phosphorus contents) in a cosmopolitan wetland species (Phragmites australis) at three spatial (inter-regional, regional, and site) scales across most of the species range in China. The species expressed large intraspecific variation in the leaf economic traits at all of the three spatial scales. It also showed strong covariation among the four leaf economic traits across the species range. The coordination among leaf economic traits resulted in LES at all three scales and the environmental variables determining variation in leaf economic traits were different among the spatial scales. Our results provide novel evidence for within-species LES at multiple spatial scales, indicating that resource trade-off could also constrain intraspecific trait variation mainly driven by climatic and/or edaphic differences.

  7. Host range validation, molecular identification, and release and establishment of a Chinese biotype of the Asian leaf beetle Lilioceris cheni Gressitt & Kimoto

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dioscorea bulbifera, a climbing vine from Asia, is a pernicious invasive plant in the southeastern USA. The plant rarely flowers but propagates by way of potato-like bulbils formed in leaf axils, which persist into the next growing season. Lilioceris cheni Gressitt & Kimoto, a foliage-feeding leaf ...

  8. Study of mineral content (Nutrients and Trace elements) in vine leaf and 4 weed species included in the vegetal cover in a Spanish vineyard.

    NASA Astrophysics Data System (ADS)

    Amorós, José Angel; Bravo, Sandra; Pérez-de-los-Reyes, Caridad; Jesús García-Navarro, Francisco; Higueras, Pablo; Campos, Juan Antonio; María Moreno, Marta

    2016-04-01

    The content of some mineral elements (Na, Ca, Mg, K, P, S, Fe, Mn, Si, Al, V, Cr, Cu, Rb, Sr, Ba, Zn, Pb, Ce, La and Nd) has been studied in vine leaf and four weed species (Mendicago lupulina L.; Malva sylvestris L., Hordeum murinum L. and Scandix pecten-veneris L.) included in the natural vegetal cover of a vineyard sited in Ciudad Real province (Central Spain). Samples were taken in May 2015, dried and milled in order to analyze them using the X Ray Fluorescence Technique. The results obtained have been compared with those measured in a vineyard located in a different site and with those suggested by the literature consulted for plants in general all around the world. The results indicate that some differences in mineral content among the weed species can be drafted. Great differences have been found in K, Si, Ca and Zn, although other elements, such as Mg, P, S, Ba and Nd, remained almost constant despite of the species. Moreover, the influence of the type of soil (different site) can give a different composition of the vine leaf in some elements. This last point is especially evident in the case of the Sr (more present in calcareous soils and leaves of plants grown on them, reaching 377 mg kg-1 versus less than 86 mg kg-1 in the non-calcareous studied soil).

  9. Herbivore responses to nutrient enrichment and landscape heterogeneity in a mangrove ecosystem.

    PubMed

    Feller, Ilka C; Chamberlain, Anne

    2007-09-01

    Complex gradients in forest structure across the landscape of offshore mangrove islands in Belize are associated with nutrient deficiency and flooding. While nutrient availability can affect many ecological processes, here we investigate how N and P enrichment interact with forest structure in three distinct zones (fringe, transition, dwarf) to alter patterns of herbivory as a function of folivory, loss of yield, and tissue mining. The effects of nutrient addition and zone varied by functional feeding group or specific herbivore. Folivory ranged from 0 to 0.4% leaf area damaged per month, but rates did not vary by either nutrient enrichment or zone. Leaf lifetime damage ranged from 3 to 10% of the total leaf area and was caused primarily by the omnivorous tree crab Aratus pisonii. We detected two distinct spatial scales of response by A. pisonii that were unrelated to nutrient treatment, i.e., most feeding damage occurred in the fringe zone and crabs fed primarily on the oldest leaves in the canopy. Loss of yield caused by the bud moth Ecdytolopha sp. varied by zone but not by nutrient treatment. A periderm-mining Marmara sp. responded positively to nutrient enrichment and closely mirrored the growth response by Rhizophora mangle across the tree height gradient. In contrast, a leaf-mining Marmara sp. was controlled by parasitoids and predators that killed >89% of its larvae. Thus, nutrient availability altered patterns of herbivory of some but not all mangrove herbivores. These findings support the hypothesis that landscape heterogeneity of the biotic and abiotic environment has species-specific effects on community structure and trophic interactions. Predicting how herbivores respond to nutrient over-enrichment in mangrove ecosystems also requires an assessment of habitat heterogeneity coupled with feeding strategies and species-specific behavior measured on multiple scales of response.

  10. Herbivore responses to nutrient enrichment and landscape heterogeneity in a mangrove ecosystem.

    PubMed

    Feller, Ilka C; Chamberlain, Anne

    2007-09-01

    Complex gradients in forest structure across the landscape of offshore mangrove islands in Belize are associated with nutrient deficiency and flooding. While nutrient availability can affect many ecological processes, here we investigate how N and P enrichment interact with forest structure in three distinct zones (fringe, transition, dwarf) to alter patterns of herbivory as a function of folivory, loss of yield, and tissue mining. The effects of nutrient addition and zone varied by functional feeding group or specific herbivore. Folivory ranged from 0 to 0.4% leaf area damaged per month, but rates did not vary by either nutrient enrichment or zone. Leaf lifetime damage ranged from 3 to 10% of the total leaf area and was caused primarily by the omnivorous tree crab Aratus pisonii. We detected two distinct spatial scales of response by A. pisonii that were unrelated to nutrient treatment, i.e., most feeding damage occurred in the fringe zone and crabs fed primarily on the oldest leaves in the canopy. Loss of yield caused by the bud moth Ecdytolopha sp. varied by zone but not by nutrient treatment. A periderm-mining Marmara sp. responded positively to nutrient enrichment and closely mirrored the growth response by Rhizophora mangle across the tree height gradient. In contrast, a leaf-mining Marmara sp. was controlled by parasitoids and predators that killed >89% of its larvae. Thus, nutrient availability altered patterns of herbivory of some but not all mangrove herbivores. These findings support the hypothesis that landscape heterogeneity of the biotic and abiotic environment has species-specific effects on community structure and trophic interactions. Predicting how herbivores respond to nutrient over-enrichment in mangrove ecosystems also requires an assessment of habitat heterogeneity coupled with feeding strategies and species-specific behavior measured on multiple scales of response. PMID:17566784

  11. Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests

    PubMed Central

    Bothwell, Lori D.; Giardina, Christian P.; Litton, Creighton M.

    2014-01-01

    Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivity of leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical montane wet forests where the warming trend may be amplified compared to tropical wet forests at lower elevations. We quantified leaf litter decomposition rates along a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forests on the Island of Hawaii. Dominant vegetation, substrate type and age, soil moisture, and disturbance history are all nearly constant across this gradient, allowing us to isolate the effect of rising MAT on leaf litter decomposition and nutrient release. Leaf litter decomposition rates were a positive linear function of MAT, causing the residence time of leaf litter on the forest floor to decline by ∼31 days for each 1 °C increase in MAT. Our estimate of the Q10 temperature coefficient for leaf litter decomposition was 2.17, within the commonly reported range for heterotrophic organic matter decomposition (1.5–2.5) across a broad range of ecosystems. The percentage of leaf litter nitrogen (N) remaining after six months declined linearly with increasing MAT from ∼88% of initial N at the coolest site to ∼74% at the warmest site. The lack of net N immobilization during all three litter collection periods at all MAT plots indicates that N was not limiting to leaf litter decomposition, regardless of temperature. These results suggest that leaf litter decay in tropical montane wet forests may be more sensitive to rising MAT than in tropical lowland wet forests, and that increased rates of N release from decomposing litter could delay or prevent progressive N limitation to net primary productivity with climate warming. PMID:25493213

  12. Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests.

    PubMed

    Bothwell, Lori D; Selmants, Paul C; Giardina, Christian P; Litton, Creighton M

    2014-01-01

    Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivity of leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical montane wet forests where the warming trend may be amplified compared to tropical wet forests at lower elevations. We quantified leaf litter decomposition rates along a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forests on the Island of Hawaii. Dominant vegetation, substrate type and age, soil moisture, and disturbance history are all nearly constant across this gradient, allowing us to isolate the effect of rising MAT on leaf litter decomposition and nutrient release. Leaf litter decomposition rates were a positive linear function of MAT, causing the residence time of leaf litter on the forest floor to decline by ∼31 days for each 1 °C increase in MAT. Our estimate of the Q 10 temperature coefficient for leaf litter decomposition was 2.17, within the commonly reported range for heterotrophic organic matter decomposition (1.5-2.5) across a broad range of ecosystems. The percentage of leaf litter nitrogen (N) remaining after six months declined linearly with increasing MAT from ∼88% of initial N at the coolest site to ∼74% at the warmest site. The lack of net N immobilization during all three litter collection periods at all MAT plots indicates that N was not limiting to leaf litter decomposition, regardless of temperature. These results suggest that leaf litter decay in tropical montane wet forests may be more sensitive to rising MAT than in tropical lowland wet forests, and that increased rates of N release from decomposing litter could delay or prevent progressive N limitation to net primary productivity with climate warming.

  13. Do climate and soil influence phenotypic variability in leaf litter, microbial decomposition and shredder consumption?

    PubMed

    Graça, M A S; Poquet, J M

    2014-03-01

    We tested the hypothesis that water stress and soil nutrient availability drive leaf-litter quality for decomposers and detritivores by relating chemical and physical leaf-litter properties and decomposability of Alnus glutinosa and Quercus robur, sampled together with edaphic parameters, across wide European climatic gradients. By regressing principal components analysis of leaf traits [N, P, condensed tannins, lignin, specific leaf area (SLA)] against environmental and soil parameters, we found that: (1) In Q. robur the condensed tannin and lignin contents increased and SLA decreased with precipitation, annual range of temperature, and soil N content, whereas leaf P increased with soil P and temperature; (2) In A. glutinosa leaves N, P, and SLA decreased and condensed tannins increased with temperature, annual range of temperature, and decreasing soil P. On the other hand, leaf P and condensed tannins increased and SLA decreased with minimum annual precipitation and towards sites with low temperature. We selected contrasting leaves in terms of quality to test decomposition and invertebrate consumption. There were intraspecific differences in microbial decomposition rates (field, Q. robur) and consumption by shredders (laboratory, A. glutinosa). We conclude that decomposition rates across ecosystems could be partially governed by climate and soil properties, affecting litter quality and therefore decomposers and detritivores. Under scenarios of global warming and increased nutrients, these results suggest we can expect species-specific changes in leaf-litter properties most likely resulting in slow decomposition with increased variance in temperatures and accelerated decomposition with P increase.

  14. Possible Roles of Strigolactones during Leaf Senescence

    PubMed Central

    Yamada, Yusuke; Umehara, Mikihisa

    2015-01-01

    Leaf senescence is a complicated developmental process that involves degenerative changes and nutrient recycling. The progress of leaf senescence is controlled by various environmental cues and plant hormones, including ethylene, jasmonic acid, salicylic acid, abscisic acid, cytokinins, and strigolactones. The production of strigolactones is induced in response to nitrogen and phosphorous deficiency. Strigolactones also accelerate leaf senescence and regulate shoot branching and root architecture. Leaf senescence is actively promoted in a nutrient-poor soil environment, and nutrients are transported from old leaves to young tissues and seeds. Strigolactones might act as important signals in response to nutrient levels in the rhizosphere. In this review, we discuss the possible roles of strigolactones during leaf senescence. PMID:27135345

  15. Putative Sugar Transporters of the Mustard Leaf Beetle Phaedon cochleariae: Their Phylogeny and Role for Nutrient Supply in Larval Defensive Glands

    PubMed Central

    Stock, Magdalena; Gretscher, René R.; Groth, Marco; Eiserloh, Simone; Boland, Wilhelm; Burse, Antje

    2013-01-01

    Background Phytophagous insects have emerged successfully on the planet also because of the development of diverse and often astonishing defensive strategies against their enemies. The larvae of the mustard leaf beetle Phaedon cochleariae, for example, secrete deterrents from specialized defensive glands on their back. The secretion process involves ATP-binding cassette transporters. Therefore, sugar as one of the major energy sources to fuel the ATP synthesis for the cellular metabolism and transport processes, has to be present in the defensive glands. However, the role of sugar transporters for the production of defensive secretions was not addressed until now. Results To identify sugar transporters in P. cochleariae, a transcript catalogue was created by Illumina sequencing of cDNA libraries. A total of 68,667 transcripts were identified and 68 proteins were annotated as either members of the solute carrier 2 (SLC2) family or trehalose transporters. Phylogenetic analyses revealed an extension of the mammalian GLUT6/8 class in insects as well as one group of transporters exhibiting distinctive conserved motifs only present in the insect order Coleoptera. RNA-seq data of samples derived from the defensive glands revealed six transcripts encoding sugar transporters with more than 3,000 counts. Two of them are exclusively expressed in the glandular tissue. Reduction in secretions production was accomplished by silencing two of four selected transporters. RNA-seq experiments of transporter-silenced larvae showed the down-regulation of the silenced transporter but concurrently the up-regulation of other SLC2 transporters suggesting an adaptive system to maintain sugar homeostasis in the defensive glands. Conclusion We provide the first comprehensive phylogenetic study of the SLC2 family in a phytophagous beetle species. RNAi and RNA-seq experiments underline the importance of SLC2 transporters in defensive glands to achieve a chemical defense for successful

  16. Relating Leaf Nitrogen, Leaf Photosynthesis and Canopy CO2 Exchange in a Temperate Winter Barley Field

    NASA Astrophysics Data System (ADS)

    Jensen, R.; Boegh, E.; Herbst, M.; Friborg, T.

    2012-12-01

    Net exchange of CO2 between the atmosphere and the soil-vegetation interface (NEE) is controlled by a wide range of biochemical and biophysical processes where leaf photosynthesis is often the most important. In mechanistically and physically based photosynthesis models (e.g. Farquhar et al. 1980) leaf nutrient status is a limiting factor for the photosynthetic capacity since it is implicitly incorporated through the parameters of maximum rate of carboxylation of CO2 (Vcmax) and the maximum rate of electron transport (Jmax). These are closely related to leaf nitrogen concentration (Na) and leaf chlorophyll content (Cab) and often show a characteristic seasonal dynamic. When simulating CO2 exchange, model outputs are sensitive to leaf photosynthetic capacity, which is labour consuming to verify through field measurements. A less time consuming method is to measure leaf "greenness" (SPAD), which is closely related to chlorophyll content and thus photosynthetic capacity. In the present study field measurements of leaf photosynthesis (LI-6400, LICOR Inc.), leaf reflectance (SPAD-502, Minolta), and LAI (LAI-2000, LICOR Inc.) were conducted on agricultural fields in Western Denmark during one growing season. The leaf photosynthesis measurements provided the basis for estimating photosynthetic capacity. SPAD measurements and LAI was measured with a higher spatial and temporal resolution. SPAD readings were calibrated against Cab and Na analyzed on leaf material in the laboratory and later correlated to photosynthetic capacity. These data were used to parameterize a coupled photosynthesis and stomatal model that was run for the growing season 2012 to estimate NEE. As a part of the hydrological observatory HOBE (hobe.dk), fluxes of greenhouse gasses are continuously measured by eddy covariance systems at three field sites in the Skjern River Catchment, Western Denmark, providing the basis for estimating the exchange of energy, water vapour, and CO2 on canopy scale. One of

  17. Foraging behaviour, nutrient intake from pasture and performance of free-range growing pigs in relation to feed CP level in two organic cropping systems.

    PubMed

    Jakobsen, M; Kongsted, A G; Hermansen, J E

    2015-12-01

    In organic pig production one of the major challenges is to be able to fulfil amino acid requirements based on organic and locally grown protein feed crops. The pig is an opportunistic omnivore with a unique capacity for foraging above and below the soil surface. It is hypothesized that direct foraging in the range area can pose an important contribution in terms of fulfilling nutrient requirements of growing pigs. Foraging activity, lucerne nutrient intake and pig performance were investigated in 36 growing pigs, foraging on lucerne or grass and fed either a standard organic pelleted feed mixture (HP: high protein) or a grain mixture containing 48% less CP (LP: low protein) compared with the high protein feed mixture, from an average live weight of 58 kg to 90 kg in a complete block design in three replicates. The pigs were fed 80% of energy recommendations and had access to 4 m2 of pasture/pig per day during the 40 days experimental period from September to October 2013. Behavioural observations were carried out 12 times over the entire experimental period. For both crops, LP pigs rooted significantly more compared with HP pigs but the effect of CP level was more pronounced in grass (44% v. 19% of all observations) compared with lucerne (28% v. 16% of all observations). Feed protein level turned out not to have any significant effect on grazing behaviour but pigs foraging on lucerne grazed significantly more than pigs foraging on grass (10% v. 4% of all observations). Daily weight gain and feed conversion ratio were significantly affected by feed protein and forage crop interactions. Compared to HP pigs, LP treated pigs had 33% lower daily weight gain (589 v. 878 g) and 31% poorer feed conversion ratio (3.75 v. 2.59 kg feed/kg weight gain) in grass paddocks, whereas in lucerne paddocks LP pigs only had 18% lower daily weight gain (741 v. 900 g) and a 14% poorer feed conversion ratio (2.95 v. 2.54 kg feed/kg weight gain) compared with HP pigs. LP pigs foraging on

  18. Host range and genetic diversity of croton yellow vein mosaic virus, a weed-infecting monopartite begomovirus causing leaf curl disease in tomato.

    PubMed

    Pramesh, D; Mandal, Bikash; Phaneendra, Chigurupati; Muniyappa, V

    2013-03-01

    Croton yellow vein mosaic virus (CYVMV) is a widely occurring begomovirus in Croton bonplandianum, a common weed in the Indian subcontinent. In this study, CYVMV (genus Begomovirus, family Geminiviridae) was transmitted by whiteflies (Bemisia tabaci) to as many as 35 plant species belonging to 11 families, including many vegetables, tobacco varieties, ornamentals and weeds. CYVMV produced bright yellow vein symptoms in croton, whereas in all the other host species, the virus produced leaf curl symptoms. CYVMV produced leaf curl in 13 tobacco species and 22 cultivars of Nicotiana tabacum and resembled tobacco leaf curl virus (TobLCV) in host reactions. However, CYVMV was distinguished from TobLCV in four differential hosts, Ageratum conyzoides, C. bonplandianum, Euphorbia geniculata and Sonchus bracyotis. The complete genome sequences of four isolates originating from northern, eastern and southern India revealed that a single species of DNA-A and a betasatellite, croton yellow vein mosaic betasatellite (CroYVMB) were associated with the yellow vein mosaic disease of croton. The sequence identity among the isolates of CYVMV DNA-A and CroYVMB occurring in diverse plant species was 91.8-97.9 % and 83.3-100 %, respectively. The CYVMV DNA-A and CroYVMB generated through rolling-circle amplification of the cloned DNAs produced typical symptoms of yellow vein mosaic and leaf curling in croton and tomato, respectively. The progeny virus from both the croton and tomato plants was transmitted successfully by B. tabaci. The present study establishes the etiology of yellow vein mosaic disease of C. bonplandianum and provides molecular evidence that a weed-infecting monopartite begomovirus causes leaf curl in tomato.

  19. Photosynthetic acclimation to high CO{sub 2} concentration varies with a plant`s capacity to adjust leaf thickness and nitrogen concentration

    SciTech Connect

    Sims, D.A.; Luo, Y.; Ball, J.T.

    1995-06-01

    Photosynthetic capacities (A{sub max}) of plants grown at high CO{sub 2} concentrations can increase, decrease or remain unchanged depending on the species and growth conditions. Increases in A{sub max} are associated with increases in leaf nitrogen concentration and/or leaf thickness. Leaf nitrogen concentration invariably decreases during growth at high CO{sub 2} while leaf thickness often increases. A{sub max} will increase during growth in high CO{sub 2} if the increase in leaf thickness outweighs the decrease in leaf nitrogen concentration. We will present a model that predicts the photosynthetic acclimation response to CO{sub 2} concentration from changes in leaf nitrogen concentration and thickness. The model was also used to predict the acclimation response under various environmental conditions. It is assumed that plants have a limited range of potential adjustment in leaf nitrogen concentration and thickness. Plants already near these limits, such as sun plants with thick leaves or low nitrogen grown plants with low leaf nitrogen concentration, may have limited potential for further adjustment in response to high CO{sub 2}. We predict that growth in high CO{sub 2} will result in upregulation of A{sub max} in low light and high nutrient environments and downregulation and low nutrient environments.

  20. Leaf Activities.

    ERIC Educational Resources Information Center

    Mingie, Walter

    Leaf activities can provide a means of using basic concepts of outdoor education to learn in elementary level subject areas. Equipment needed includes leaves, a clipboard with paper, and a pencil. A bag of leaves may be brought into the classroom if weather conditions or time do not permit going outdoors. Each student should pick a leaf, examine…

  1. Nutrient Value of Leaf vs. Seed

    PubMed Central

    Edelman, Marvin; Colt, Monica

    2016-01-01

    Major differences stand out between edible leaves and seeds in protein quality, vitamin, and mineral concentrations and omega 6/omega 3 fatty acid ratios. Data for seeds (wheat, rice, corn, soy, lentil, chick pea) are compared with corresponding data for edible green leaves (kale, spinach, broccoli, duckweed). An x/y representation of data for lysine and methionine content highlights the group differences between grains, pulses, leafy vegetables, and animal foods. Leaves come out with flying colors in all these comparisons. The perspective ends with a discussion on “So why do we eat mainly seeds?” PMID:27493937

  2. Nutrient Value of Leaf vs. Seed.

    PubMed

    Edelman, Marvin; Colt, Monica

    2016-01-01

    Major differences stand out between edible leaves and seeds in protein quality, vitamin, and mineral concentrations and omega 6/omega 3 fatty acid ratios. Data for seeds (wheat, rice, corn, soy, lentil, chick pea) are compared with corresponding data for edible green leaves (kale, spinach, broccoli, duckweed). An x/y representation of data for lysine and methionine content highlights the group differences between grains, pulses, leafy vegetables, and animal foods. Leaves come out with flying colors in all these comparisons. The perspective ends with a discussion on "So why do we eat mainly seeds?" PMID:27493937

  3. Nutrient value of leaf versus seed

    NASA Astrophysics Data System (ADS)

    Edelman, Marvin; Holt, Monica

    2016-07-01

    Major differences stand out between edible leaves and seeds in protein quality, vitamin and mineral concentrations and omega 6 / omega 3 fatty acid ratios. Data for seeds (wheat, rice, corn, soy, lentil, chick pea) are compared with corresponding data for edible green leaves (kale, spinach, broccoli, duckweed). An x/y representation of data for lysine and methionine content highlights the group differences between grains, pulses, leafy vegetables and animal foods. Leaves come out with flying colors in all these comparisons. The perspective ends with a discussion on “So why do we eat mainly seeds?”

  4. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is within the range represented...

  5. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is within the range represented...

  6. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is within the range represented...

  7. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is within the range represented...

  8. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is within the range represented...

  9. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is within the range represented...

  10. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which is within the range represented...

  11. The relationship of leaf photosynthetic traits – Vcmax and Jmax – to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study

    PubMed Central

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-01-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm−2), increasing leaf P from 0.05 to 0.22 gm−2 nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  12. The relationship of leaf photosynthetic traits - V cmax and J max - to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study.

    PubMed

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-08-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (V cmax) and the maximum rate of electron transport (J max). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between V cmax and J max and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between V cmax and J max and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of V cmax and J max with leaf N, P, and SLA. V cmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of V cmax to leaf N. J max was strongly related to V cmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm(-2)), increasing leaf P from 0.05 to 0.22 gm(-2) nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of J max to V cmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting.

  13. Leaf exsertion, leaf elongation, and leaf senescence in Eriophorum vaginatum and Carex Bigelowii

    SciTech Connect

    Shaver, G.R.; Yandow, T.; Laundre, J.

    1990-01-01

    Most of the common sedges of arctic vegetation show a pattern of leaf production in which the exsertion and elongation of new leaves is more or less simultaneous with the senescence of old leaves. The present study was designed to increase our understanding of the variability sequential leaf production by arctic sedges, and to determine some of the controls on that variability. We did this in two ways: first, we compared the sequential patterns of leaf growth and senescence in E. vaginatum with those of Carex Bigelowii Torr. at two tussock tundra sites near Toolik Lake on the North Slope of Alaska. Second, we compared the responses of leaf growth in these species in control and fertilized plots and in two microenvironments thought to differ sharply in nutrient availability and total productivity. 29 refs., 28 figs., 2 tabs.

  14. Leaf breakdown in streams differing in catchment land use

    USGS Publications Warehouse

    Paul, M.J.; Meyer, J.L.; Couch, C.A.

    2006-01-01

    1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runoff was significantly higher in urban and suburban catchments that had higher impervious surface cover than forested or agricultural catchments. 4. We propose that processes accelerating leaf breakdown in agricultural and urban streams were not the same: faster breakdown in agricultural streams was due to increased biological activity as a result of nutrient enrichment, whereas faster breakdown in urban streams was a result of physical fragmentation resulting from higher storm runoff. ?? 2006 The Authors.

  15. Nutrient dynamics and decomposition of riparian Arundinaria gigantea (Walt.)Muhl. leaves in southern Illinois

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf litter quality and quantity can influence soil nutrient dynamics and stream productivity through decomposition and serving as allochthonous stream inputs. Leaf deposition, nitrogen (N)-resorption efficiency and proficiency, and decomposition rates were analyzed in riparian stands of Arundinaria...

  16. Noninvasive detection of plant nutrient stress using fiber optic spectrophotometry

    NASA Astrophysics Data System (ADS)

    Chen, Jun-Wei; Asundi, Anand K.; Liew, Oi Wah; Boey, William S. L.

    2001-05-01

    In a previous paper, we described the use of fiber optic spectrophotometry as a non-destructive and sensitive method to detect early symptoms of plant nutrient deficiency. We report further developments of our work on Brassica chinensis var parachinensis (Bailey) showing reproducibility of our data collected at a different seasonal period. Plants at the mid-log growth phase were subjected to nutrient stress by transferring them to nitrate- and calcium- deficient nutrient solution in a standing aerated hydroponic system. After tracking changes in leaf reflectance by FOSpectr for nine days, the plants were returned to complete nutrient solution and their recovery was monitored for a further nine days. The responses of nutrient stressed plants were compared with those grown under complete nutrient solution over the 18-day trial period. We also compared the sensitivity of FOSpectr detection against plant growth measurements vis-a-vis average leaf number and leaf width and show that the former method gave an indication of nutrient stress much earlier than the latter. In addition, this work indicated that while normal and nutrient-stressed plants could not be distinguished within the first 7 days by tracking plant growth indicators, stressed plants did show a clear decline in average leaf number and leaf width in later stages of growth even after the plants were returned to complete nutrient solution. The results further reinforce the need for early detection of nutrient stress, as late remedial action could not reverse the loss in plant growth in later stages of plant development.

  17. Effects of forest management practices in temperate beech forests on bacterial and fungal communities involved in leaf litter degradation.

    PubMed

    Purahong, Witoon; Kapturska, Danuta; Pecyna, Marek J; Jariyavidyanont, Katalee; Kaunzner, Jennifer; Juncheed, Kantida; Uengwetwanit, Tanaporn; Rudloff, Renate; Schulz, Elke; Hofrichter, Martin; Schloter, Michael; Krüger, Dirk; Buscot, François

    2015-05-01

    Forest management practices (FMPs) significantly influence important ecological processes and services in Central European forests, such as leaf litter decomposition and nutrient cycling. Changes in leaf litter diversity, and thus, its quality as well as microbial community structure and function induced by different FMPs were hypothesized to be the main drivers causing shifts in decomposition rates and nutrient release in managed forests. In a litterbag experiment lasting 473 days, we aimed to investigate the effects of FMPs (even-aged timber management, selective logging and unmanaged) on bacterial and fungal communities involved in leaf litter degradation over time. Our results showed that microbial communities in leaf litter were strongly influenced by both FMPs and sampling date. The results from nonmetric multidimensional scaling (NMDS) ordination revealed distinct patterns of bacterial and fungal successions over time in leaf litter. We demonstrated that FMPs and sampling dates can influence a range of factors, including leaf litter quality, microbial macronutrients, and pH, which significantly correlate with microbial community successions. PMID:25749938

  18. Effects of forest management practices in temperate beech forests on bacterial and fungal communities involved in leaf litter degradation.

    PubMed

    Purahong, Witoon; Kapturska, Danuta; Pecyna, Marek J; Jariyavidyanont, Katalee; Kaunzner, Jennifer; Juncheed, Kantida; Uengwetwanit, Tanaporn; Rudloff, Renate; Schulz, Elke; Hofrichter, Martin; Schloter, Michael; Krüger, Dirk; Buscot, François

    2015-05-01

    Forest management practices (FMPs) significantly influence important ecological processes and services in Central European forests, such as leaf litter decomposition and nutrient cycling. Changes in leaf litter diversity, and thus, its quality as well as microbial community structure and function induced by different FMPs were hypothesized to be the main drivers causing shifts in decomposition rates and nutrient release in managed forests. In a litterbag experiment lasting 473 days, we aimed to investigate the effects of FMPs (even-aged timber management, selective logging and unmanaged) on bacterial and fungal communities involved in leaf litter degradation over time. Our results showed that microbial communities in leaf litter were strongly influenced by both FMPs and sampling date. The results from nonmetric multidimensional scaling (NMDS) ordination revealed distinct patterns of bacterial and fungal successions over time in leaf litter. We demonstrated that FMPs and sampling dates can influence a range of factors, including leaf litter quality, microbial macronutrients, and pH, which significantly correlate with microbial community successions.

  19. Ocean nutrients

    NASA Astrophysics Data System (ADS)

    Boyd, Philip W.; Hurd, Catriona L.

    Nutrients provide the chemical life-support system for phytoplankton in the ocean. Together with the carbon fixed during photosynthesis, nutrients provide the other elements, such as N and P, needed to synthesize macromolecules to build cellular constituents such as ribosomes. The makeup of these various biochemicals, such as proteins, pigments, and nucleic acids, together determine the elemental stoichiometry of an individual phytoplankton cell. The stoichiometry of different phytoplankton species or groups will vary depending on the proportions of distinct cellular machinery, such as for growth or resource acquisition, they require for their life strategies. The uptake of nutrients by phytoplankton helps to set the primary productivity, and drives the biological pump, of the global ocean. In the case of nitrogen, the supply of nutrients is categorized as either new or regenerated. The supply of new nitrogen, such as nitrate upwelled from the ocean' interior or biological nitrogen fixation, is equal to the vertical export of particular organic matter from the upper ocean on a timescale of years. Nutrients such as silica can also play a structural role in some phytoplankton groups, such as diatoms, where they are used to synthesize a siliceous frustule that offers some mechanical protection from grazers. In this chapter, we also explore nutrient uptake kinetics, patterns in nutrient distributions in space and time, the biogeochemical cycle of nitrogen, the atmospheric supply of nutrients, departures from the Redfield ratio, and whether nutrient distributions and cycling will be altered in the future

  20. Leaf Development

    PubMed Central

    2013-01-01

    Leaves are the most important organs for plants. Without leaves, plants cannot capture light energy or synthesize organic compounds via photosynthesis. Without leaves, plants would be unable perceive diverse environmental conditions, particularly those relating to light quality/quantity. Without leaves, plants would not be able to flower because all floral organs are modified leaves. Arabidopsis thaliana is a good model system for analyzing mechanisms of eudicotyledonous, simple-leaf development. The first section of this review provides a brief history of studies on development in Arabidopsis leaves. This history largely coincides with a general history of advancement in understanding of the genetic mechanisms operating during simple-leaf development in angiosperms. In the second section, I outline events in Arabidopsis leaf development, with emphasis on genetic controls. Current knowledge of six important components in these developmental events is summarized in detail, followed by concluding remarks and perspectives. PMID:23864837

  1. Damped leaf flexure hinge

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  2. Damped leaf flexure hinge.

    PubMed

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage. PMID:26026549

  3. Nutrient management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient management has been defined as “the science and art directed to link soil, crop, weather and hydrologic factors with cultural, irrigation and soil and water conservation practices to achieve the goals of optimizing nutrient use efficiency, yields, crop quality, and economic returns, while r...

  4. Available nutrients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar technology may contribute to the recovery and recycling of plant nutrients and thus add a fertilizer value to the biochar. Total nutrient content in biochars varies greatly and is mainly dependent on feedstock elemental composition and to a lesser extent on pyrolysis conditions. Availability...

  5. Calcium biofortification and bioaccessibility in soilless "baby leaf" vegetable production.

    PubMed

    D'Imperio, Massimiliano; Renna, Massimiliano; Cardinali, Angela; Buttaro, Donato; Serio, Francesco; Santamaria, Pietro

    2016-12-15

    Calcium is an essential nutrient for human health, because it is a structural component and takes part in a variety of biological processes. The aim of this study was to increase Ca content of baby leaf vegetables (BLV: basil, mizuna, tatsoi and endive), as fresh-cut products. For the production of biofortified BLV, a floating system with two level of Ca (100 and 200mgL(-1)) in the nutrient solution was used. In addition, the assessment of bioaccessibility of Ca, by in vitro digestion process, was performed. In all vegetables, the Ca biofortification (200mgL(-1)) caused a significant Ca enrichment (9.5% on average) without affecting vegetables growth, oxalate contents and marketable quality. Calcium bioaccessibility ranged from 25% (basil) to 40% (endive) but the biofortified vegetables showed more bioaccessible Ca. These results underline the possibility to obtain Ca biofortified BLV by using agronomic approaches. PMID:27451166

  6. What determines a leaf's shape?

    PubMed

    Dkhar, Jeremy; Pareek, Ashwani

    2014-01-01

    The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf; initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation; besides, recent research has identified new players such as APUM23, known to specify leaf polarity. In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia. PMID:25584185

  7. What determines a leaf's shape?

    PubMed

    Dkhar, Jeremy; Pareek, Ashwani

    2014-01-01

    The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf; initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation; besides, recent research has identified new players such as APUM23, known to specify leaf polarity. In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia.

  8. STABLE ISOTOPE STUDIES ON THE USE OF MARINE-DERIVED NUTRIENTS BY COHO SALMON JUVENILES IN AN OREGON COAST RANGE STREAM

    EPA Science Inventory

    We are using stable isotopes (13C, 15N, 34S) to study the use of salmon carcasses, eggs and fry by over-wintering coho juveniles in two streams of the Oregon Coast Range. Our work is paired with detailed data gathering on stream habitat condition, temperature, chemistry and PIT-t...

  9. Summer (sub-arctic) versus winter (sub-tropical) production affects on spinach leaf bio-nutrients: Vitamins (C, E, Folate, K1, provitamin A), lutein, phenolics, and antioxidants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comparison of spinach (Spinacia oleracea L.) cultivars Lazio and Samish grown during the summer solstice in the sub-arctic versus the winter solstice in the sub-tropics provided insight into interactions between plant environment (day length, light intensity, ambient temperatures), cultivar and leaf...

  10. Nutrient addition differentially affects ecological processes of Avicennia germinans in nitrogen versus phosphorus limited mangrove ecosystems

    USGS Publications Warehouse

    Feller, Ilka C.; Lovelock, C.E.; McKee, K.L.

    2007-01-01

    Nutrient over-enrichment is a major threat to marine environments, but system-specific attributes of coastal ecosystems may result in differences in their sensitivity and susceptibility to eutrophication. We used fertilization experiments in nitrogen (N)- and phosphorus (P)-limited mangrove forests to test the hypothesis that alleviating different kinds of nutrient limitation may have different effects on ecosystem structure and function in natural systems. We compared a broad range of ecological processes to determine if these systems have different thresholds where shifts might occur in nutrient limitation. Growth responses indicated N limitation in Avicennia germinans (black mangrove) forests in the Indian River Lagoon (IRL), Florida, and P limitation at Twin Cays, Belize. When nutrient deficiency was relieved, A. germinans grew out of its stunted form by increasing wood relative to leaf biomass and shoot length relative to lateral growth. At the P-limited site, P enrichment (+P) increased specific leaf area, N resorption, and P uptake, but had no effect on P resorption. At the N-limited site, +N increased both N and P resorption, but did not alter biomass allocation. Herbivory was greater at the P-limited site and was unaffected by +P, whereas +N led to increased herbivory at the N-limited site. The responses to nutrient enrichment depended on the ecological process and limiting nutrient and suggested that N- versus P-limited mangroves do have different thresholds. +P had a greater effect on more ecological processes at Twin Cays than did +N at the IRL, which indicated that the P-limited site was more sensitive to nutrient loading. Because of this sensitivity, eutrophication is more likely to cause a shift in nutrient limitation at P-limited Twin Cays than N-limited IRL. ?? 2007 Springer Science+Business Media, LLC.

  11. Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

    PubMed

    Gautam, Mukesh Kumar; Lee, Kwang-Sik; Song, Byeong-Yeol; Lee, Dongho; Bong, Yeon-Sik

    2016-05-01

    Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems. PMID:26915037

  12. Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

    PubMed

    Gautam, Mukesh Kumar; Lee, Kwang-Sik; Song, Byeong-Yeol; Lee, Dongho; Bong, Yeon-Sik

    2016-05-01

    Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.

  13. Seasonal microbial and nutrient responses during a 5-year reduction in the daily temperature range of soil in a Chihuahuan Desert ecosystem.

    PubMed

    van Gestel, Natasja C; Dhungana, Nirmala; Tissue, David T; Zak, John C

    2016-01-01

    High daily temperature range of soil (DTRsoil) negatively affects soil microbial biomass and activity, but its interaction with seasonal soil moisture in regulating ecosystem function remains unclear. For our 5-year field study in the Chihuahuan Desert, we suspended shade cloth 15 cm above the soil surface to reduce daytime temperature and increase nighttime soil temperature compared to unshaded plots, thereby reducing DTRsoil (by 5 ºC at 0.2 cm depth) without altering mean temperatures. Microbial biomass production was primarily regulated by seasonal precipitation with the magnitude of the response dependent on DTRsoil. Reduced DTRsoil more consistently increased microbial biomass nitrogen (MBN; +38%) than microbial biomass carbon (MBC) with treatment responses being similar in spring and summer. Soil respiration depended primarily on soil moisture with responses to reduced DTRsoil evident only in wetter summer soils (+53%) and not in dry spring soils. Reduced DTRsoil had no effect on concentrations of dissolved organic C, soil organic matter (SOM), nor soil inorganic N (extractable NO3 (-)-N + NH4 (+)-N). Higher MBN without changes in soil inorganic N suggests faster N cycling rates or alternate sources of N. If N cycling rates increased without a change to external N inputs (atmospheric N deposition or N fixation), then productivity in this desert system, which is N-poor and low in SOM, could be negatively impacted with continued decreases in daily temperature range. Thus, the future N balance in arid ecosystems, under conditions of lower DTR, seems linked to future precipitation regimes through N deposition and regulation of soil heat load dynamics.

  14. Seasonal microbial and nutrient responses during a 5-year reduction in the daily temperature range of soil in a Chihuahuan Desert ecosystem.

    PubMed

    van Gestel, Natasja C; Dhungana, Nirmala; Tissue, David T; Zak, John C

    2016-01-01

    High daily temperature range of soil (DTRsoil) negatively affects soil microbial biomass and activity, but its interaction with seasonal soil moisture in regulating ecosystem function remains unclear. For our 5-year field study in the Chihuahuan Desert, we suspended shade cloth 15 cm above the soil surface to reduce daytime temperature and increase nighttime soil temperature compared to unshaded plots, thereby reducing DTRsoil (by 5 ºC at 0.2 cm depth) without altering mean temperatures. Microbial biomass production was primarily regulated by seasonal precipitation with the magnitude of the response dependent on DTRsoil. Reduced DTRsoil more consistently increased microbial biomass nitrogen (MBN; +38%) than microbial biomass carbon (MBC) with treatment responses being similar in spring and summer. Soil respiration depended primarily on soil moisture with responses to reduced DTRsoil evident only in wetter summer soils (+53%) and not in dry spring soils. Reduced DTRsoil had no effect on concentrations of dissolved organic C, soil organic matter (SOM), nor soil inorganic N (extractable NO3 (-)-N + NH4 (+)-N). Higher MBN without changes in soil inorganic N suggests faster N cycling rates or alternate sources of N. If N cycling rates increased without a change to external N inputs (atmospheric N deposition or N fixation), then productivity in this desert system, which is N-poor and low in SOM, could be negatively impacted with continued decreases in daily temperature range. Thus, the future N balance in arid ecosystems, under conditions of lower DTR, seems linked to future precipitation regimes through N deposition and regulation of soil heat load dynamics. PMID:26391383

  15. Leaf hydraulics II: vascularized tissues.

    PubMed

    Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D

    2014-01-01

    Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements.

  16. Light, nutrients, and herbivore growth in oligotrophic streams

    SciTech Connect

    Hill, Walter R; Smith, John G; Stewart, Arthur J

    2010-02-01

    The light : nutrient hypothesis posits that herbivore growth is increasingly constrained by low food quality as the ratio of light to nutrients increases in aquatic ecosystems. We tested predictions of this hypothesis by examining the effects of large seasonal cycles in light and nutrients on the mineral content of periphyton and the growth rate of a dominant herbivore (the snail Elimia clavaeformis) in two oligotrophic streams. Streambed irradiances in White Oak Creek and Walker Branch (eastern Tennessee, USA) varied dramatically on a seasonal basis due to leaf phenology in the surrounding deciduous forests and seasonal changes in sun angle. Concentrations of dissolved nutrients varied inversely with light, causing light : nitrate and light : phosphate to range almost 100-fold over the course of any individual year. Periphyton nitrogen and phosphorus concentrations were much lower than the concentrations of these elements in snails, and they bottomed out in early spring when streambed irradiances were highest. Snail growth, however, peaked in early spring when light:nutrient ratios were highest and periphyton nutrient concentrations were lowest, Growth was linearly related to primary production (accounting for up to 85% of growth variance in individual years), which in turn was driven by seasonal variation in light. Conceptual models of herbivore growth indicate that growth should initially increase as increasing light levels stimulate primary production, but then level off, and then decrease as the negative effects of decreasing algal nutrient content override the positive effects of increased food production. Our results showed no evidence of an inflection point where increasing ratios of light to nutrients negatively affected growth. Snail growth in these intensively grazed streams is probably unaffected by periphyton nutrient content because exploitative competition for food reduces growth rates to levels where the demand for nitrogen and phosphorus is small

  17. Light, nutrients, and herbivore growth in oligotrophic streams.

    PubMed

    Hill, Walter R; Smith, John G; Stewart, Arthur J

    2010-02-01

    The light : nutrient hypothesis posits that herbivore growth is increasingly constrained by low food quality as the ratio of light to nutrients increases in aquatic ecosystems. We tested predictions of this hypothesis by examining the effects of large seasonal cycles in light and nutrients on the mineral content of periphyton and the growth rate of a dominant herbivore (the snail Elimia clavaeformis) in two oligotrophic streams. Streambed irradiances in White Oak Creek and Walker Branch (eastern Tennessee, USA) varied dramatically on a seasonal basis due to leaf phenology in the surrounding deciduous forests and seasonal changes in sun angle. Concentrations of dissolved nutrients varied inversely with light, causing light : nitrate and light : phosphate to range almost 100-fold over the course of any individual year. Periphyton nitrogen and phosphorus concentrations were much lower than the concentrations of these elements in snails, and they bottomed out in early spring when streambed irradiances were highest. Snail growth, however, peaked in early spring when light:nutrient ratios were highest and periphyton nutrient concentrations were lowest, Growth was linearly related to primary production (accounting for up to 85% of growth variance in individual years), which in turn was driven by seasonal variation in light. Conceptual models of herbivore growth indicate that growth should initially increase as increasing light levels stimulate primary production, but then level off, and then decrease as the negative effects of decreasing algal nutrient content override the positive effects of increased food production. Our results showed no evidence of an inflection point where increasing ratios of light to nutrients negatively affected growth. Snail growth in these intensively grazed streams is probably unaffected by periphyton nutrient content because exploitative competition for food reduces growth rates to levels where the demand for nitrogen and phosphorus is small

  18. Cedar leaf oil poisoning

    MedlinePlus

    Cedar leaf oil is made from some types of cedar trees. Cedar leaf oil poisoning occurs when someone swallows this substance. ... The substance in cedar leaf oil that can be harmful is thujone (a hydrocarbon).

  19. Nutrient availability in rangeland soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil nutrient availability is a major factor influencing plant community composition and susceptibility to invasion by exotic plants. We used resin capsules to integrate, over time, soil nutrient availability at sagebrush-grassland elevation transects in the east Tintic range of Utah and in the Shos...

  20. Key Nutrients.

    ERIC Educational Resources Information Center

    Federal Extension Service (USDA), Washington, DC.

    Lessons written to help trainer agents prepare aides for work with families in the Food and Nutrition Program are presented in this booklet. The key nutrients discussed in the 10 lessons are protein, carbohydrates, fat, calcium, iron, iodine, and Vitamins A, B, C, and D. the format of each lesson is as follows: Purpose, Presentation, Application…

  1. Structure and Function of Shisham Forests in Central Himalaya, India: Nutrient Dynamics

    PubMed Central

    LODHIYAL, NEELU; LODHIYAL, L. S.; PANGTEY, Y. P. S.

    2002-01-01

    The structure and function of Shisham (Dalbergia sissoo Roxb.) forests were investigated in relation to nutrient dynamics in 5‐ to 15‐year‐old stands growing in central Himalaya. Nutrient concentrations and storage in different layers of vegetation were in the order: tree > shrub > herb. Forest soil, litter and vegetation accounted for 80·1–91·9, 1·0–1·5 and 7·0–18·4 %, respectively, of the total nutrients in the system. There were considerable reductions (trees 32·8–43·1; shrubs 26·2–32·4; and herbs 18·8–22·2 %) in nutrient concentrations of leaves during senescence. Nutrient uptake by the vegetation as a whole and also by the different components, with and without adjustment for internal recycling, was investigated. Annual transfer of litter nutrients to the soil from vegetation was 74·8–108·4 kg ha–1 year–1 N, 5·6–8·4 kg ha–1 year–1 P and 38·7–46·9 kg ha–1 year–1 K. Turnover rate and time for different nutrients ranged between 56 and 66 % year–1 and 1·5 and 1·8 years, respectively. The turnover rate of litter indicates that over 50 % of nutrients in litter on the forest floor are released, which ultimately enhances the productivity of the forest stand. The nutrient use efficiency in Shisham forests ranged from 136 to 143 kg ha–1 year–1 for N, 1441 to 1570 kg ha–1 year–1 for P and 305 to 311 kg ha–1 year–1 for K. Compared with natural oak forest (265 kg ha–1 year–1) and an exotic eucalypt plantation (18 kg ha–1 year–1), a higher proportion of nutrients was retranslocated in Shisham forests, largely because of higher leaf tissue nutrient concentrations. This indicates a lower nutrient use efficiency of Shisham compared with eucalypt and oak. Compartment models for nutrient dynamics have been developed to represent the distribution of nutrients pools and net annual fluxes within the system. PMID:12096819

  2. [Citrus boron nutrient level and its impact factors in the Three Gorges Reservoir region of Chongqing, China].

    PubMed

    Zhou, Wei; Peng, Liang-Zhi; Chun, Chang-Pin; Jiang, Cai-Lun; Ling, Li-Li; Wang, Nan-Qi; Xing, Fei; Huang, Yi

    2014-04-01

    To investigate the level of boron nutrient in citrus and its impact factors, a total of 954 citrus leaf samples and 302 soil samples were collected from representative orchards in the 12 main citrus production counties in the Three Gorges Reservoir region of Chongqing to determine the boron content in citrus leaves, as well as the relationships between leaf boron content with soil available boron content, soil pH value, cultivar, rootstock and the age of tree. Results indicated that the leaf samples from 41.6% orchards (< 35 mg x kg(-1)) and the soil samples from 89.4% orchards (< 0.5 mg x kg(-1)) were boron insufficient. The correlation of leaf boron content and soil available boron content was not significant. The soil pH, cultivar, rootstock and the age of tree did affect the leaf boron content. The leaves from the orchards with soil pH of 4.5-6.4 demonstrated significantly higher boron contents than with the soil pH of 6.5-8.5. The leaf boron contents in the different cultivars was ranged as Satsuma mandarin > pomelo > valencia orange > sweet orange > tangor > navel orange. The citrus on trifoliate orange and sour pomelo rootstocks had significantly higher leaf boron contents than on Carrizo citrange and red tangerine rootstocks. Compared with the adult citrus trees (above 8 year-old), 6.6% more of leaf samples of younger trees (3 to 8 year-old) contained boron contents in the optimum range (35-100 mg x kg(-1)). PMID:25011290

  3. [Citrus boron nutrient level and its impact factors in the Three Gorges Reservoir region of Chongqing, China].

    PubMed

    Zhou, Wei; Peng, Liang-Zhi; Chun, Chang-Pin; Jiang, Cai-Lun; Ling, Li-Li; Wang, Nan-Qi; Xing, Fei; Huang, Yi

    2014-04-01

    To investigate the level of boron nutrient in citrus and its impact factors, a total of 954 citrus leaf samples and 302 soil samples were collected from representative orchards in the 12 main citrus production counties in the Three Gorges Reservoir region of Chongqing to determine the boron content in citrus leaves, as well as the relationships between leaf boron content with soil available boron content, soil pH value, cultivar, rootstock and the age of tree. Results indicated that the leaf samples from 41.6% orchards (< 35 mg x kg(-1)) and the soil samples from 89.4% orchards (< 0.5 mg x kg(-1)) were boron insufficient. The correlation of leaf boron content and soil available boron content was not significant. The soil pH, cultivar, rootstock and the age of tree did affect the leaf boron content. The leaves from the orchards with soil pH of 4.5-6.4 demonstrated significantly higher boron contents than with the soil pH of 6.5-8.5. The leaf boron contents in the different cultivars was ranged as Satsuma mandarin > pomelo > valencia orange > sweet orange > tangor > navel orange. The citrus on trifoliate orange and sour pomelo rootstocks had significantly higher leaf boron contents than on Carrizo citrange and red tangerine rootstocks. Compared with the adult citrus trees (above 8 year-old), 6.6% more of leaf samples of younger trees (3 to 8 year-old) contained boron contents in the optimum range (35-100 mg x kg(-1)).

  4. Leaf lifespan is positively correlated with periods of leaf production and reproduction in 49 herb and shrub species.

    PubMed

    Lan Li, Fang; Liu, Xin; Bao, Wei Kai

    2016-06-01

    Leaf life span and plant phenology are central elements in strategies for plant carbon gain and nutrient conservation. Although few studies have found that leaf life span correlate with the patterns of leaf dynamics and reproductive output, but there have not been sufficient conclusive tests for relationships between leaf life span and plant phenological traits, the forms and strengths of such relationships are poorly understood. This study was conducted with 49 herb and shrub species collected from the eastern portion of the Tibetan Plateau and grown together in a common garden setting. We investigated leaf life span, the periods of leaf production and death, the time lag between leaf production and death, and the period of plant reproduction (i.e., flowering and fruiting). Interspecific relationships of leaf life span with leaf dynamics and reproduction period were determined. Leaf production period was far longer than leaf death period and largely reflected the interspecific variation of leaf life span. Moreover, leaf life span was positively correlated with the length of reproduction (i.e., flowering and fruiting) period. These relationships were generally consistent across different subgroups of species (herbs vs. shrubs) and indicate potentially widely applicable relationships between LLS and aboveground phenology. We concluded that leaf life span is associated not simply with the dynamics of the leaf itself but with reproduction period. The results demonstrate a plant trade-off in resource allocation between production and reproduction and a coordinated arrangement of leaves, flowers, and fruits in their time investment. Our results provide insight into the relationship between leaf life span and plant phenology. PMID:27398191

  5. [Study on the polarized reflectance characteristics of single greenhouse tomato nutrient deficiency leaves].

    PubMed

    Zhu, Wen-Jing; Mao, Han-Ping; Liu, Hong-Yu; Zhang, Xiao-Dong; Ni, Ji-Heng

    2014-01-01

    In order to improve accuracy of quantitative analysis model for the greenhouse tomato nitrogen, phosphorus and potassium nutrient stress, and explore the advantages of polarization non-destructive detection in single-leaf plants scale, polarized reflectance characteristics of greenhouse nutrient deficiency tomato leaves in different growing seasons and different deficiency extents were both examined via means of polarized reflectance spectroscopy system, which was self-developed by the research group. The main factors with effects on the polarized reflectance characteristics of tomato leaves were discussed, such as incident zenith angle, azimuth angle, detection zenith angle, light source polarizer degree, and detector polarizer degree. Experiments were carried out to verify the optimum level of above five parameters by means of range analysis of orthogonal experiments, through that way we can know the best angle combination of five parameters. Based on the above analysis, the angle combination and sorting of detecting tomato nutrients deficiency leaves via means of polarization spectroscopy system were obtained as follows: incident zenith angle 60 degrees, light source polarizer degree 0 degrees, detection zenith angle 45 degrees, detector polarizer degree 45 degrees and azimuth angle 180 degrees. At the same time, both the spectra of nitrogen, phosphorus and potassium deficiency leaves in different growth stages and different deficiency extent leaves were compared with each other. Results show that there is a positive correlation between the greenhouse nutrient deficiency tomato leaves growth cycle and tomato leaves polarized reflectance spectra. Nutrient excess or nutrient deficiency can both lead to polarized reflectance decline and polarized reflectance decline extent of greenhouse tomato leaves is more obvious during the fruiting and harvest period. This paper has a certain theoretical and practical significance in the research on nutrition rapid detection on

  6. [Ecological stoichiometric characteristics in leaf and litter under different vegetation types of Zhifanggou watershed on the Loess Plateau, China].

    PubMed

    Li, Xin; Zeng, Ouan-chao; An, Shao-Shan; Dong, Yang-Hong; Li, Ya-Yun

    2015-03-01

    The purpose was to characterize the effects of vegetation types on plant leaf and litter carbon (C), nitrogen (N), phosphorus (P), potassium (K) and C: N: P: K ecological stoichiometric characteristics in seven dominant plant species, including Robinia pseudoacacia, Syringa, Sophora viciifolia, Hippophae rhamnoides, Rosa xanthina, Artemisia sacrorum, Artemisia giraldii, of Zhifanggou Watershed on the Loess Plateau, China. This paper indicated the differences between the contents of C, N, P and K and the characteristics of ecological stoichiometric in the different vegetation types, including forest type, shrub type and grass type. Concentrations of C, N, P and K were measured, and C: N: P: K was estimated for different vegetation types. There were no significant differences in leaf C, N and P concentrations among the three vegetation types. But significant differences in leaf K concentration existed, and the K concentration in leaf was the highest in grass type, and the lowest in shrub type. The contents of C, N, P and K in leaf were much higher than those in litter, especially in shrub and grass types. The resorption efficiencies of C, N, P and K were different, and their ranges varied 6.16%-22.84%, 24.38%-65.18%, 22.38%-77.16% and 60.99%- 89.35%, respectively. Grass type had the highest C, P and K resorption efficiencies, and the lowest N resorption efficiency. Values of the N: P ratio in leaf varied in the range of 12.14-19.17, and varied in the range of 12.84-30.67 in litter. Values of the N: P ratio in leaf were the highest in shrub type (19. 17), and the lowest in grass (12. 14), indicating that the growth of shrub plants was limited by P, while the growth of grass plants was limited by N. The K concentration in leaf was significantly negatively correlated with values of the N: P ratio in leaf, and the K concentration in litter was significantly negatively correlated with values of the C: P ratio in leaf. Findings in this study highlighted the characteristics

  7. Fiber optic spectrophotometry monitoring of plant nutrient deficiency under hydroponic culture conditions

    NASA Astrophysics Data System (ADS)

    Liew, Oi Wah; Boey, William S. L.; Asundi, Anand K.; Chen, Jun-Wei; He, Duo-Min

    1999-05-01

    In this paper, fiber optic spectrophotometry (FOSpectr) was adapted to provide early detection of plant nutrient deficiency by measuring leaf spectral reflectance variation resulting from nutrient stress. Leaf reflectance data were obtained form a local vegetable crop, Brassica chinensis var parachinensis (Bailey), grown in nitrate-nitrogen (N)- and calcium (Ca)- deficient hydroponics nutrient solution. FOSpectr analysis showed significant differences in leaf reflectance within the first four days after subjecting plants to nutrient-deficient media. Recovery of the nutrient-stressed plants could also be detected after transferring them back to complete nutrient solution. In contrast to FOSpectr, plant response to nitrogen and calcium deficiency in terms of reduced growth and tissue elemental levels was slower and less pronounced. Thus, this study demonstrated the feasibility of using FOSpectr methodology as a non-destructive alternative to augment current methods of plant nutrient analysis.

  8. Last-Century Increases in Intrinsic Water-Use Efficiency of Grassland Communities Have Occurred over a Wide Range of Vegetation Composition, Nutrient Inputs, and Soil pH1[OPEN

    PubMed Central

    Köhler, Iris H.; Macdonald, Andy J.; Schnyder, Hans

    2016-01-01

    Last-century climate change has led to variable increases of the intrinsic water-use efficiency (Wi; the ratio of net CO2 assimilation to stomatal conductance for water vapor) of trees and C3 grassland ecosystems, but the causes of the variability are not well understood. Here, we address putative drivers underlying variable Wi responses in a wide range of grassland communities. Wi was estimated from carbon isotope discrimination in archived herbage samples from 16 contrasting fertilizer treatments in the Park Grass Experiment, Rothamsted, England, for the 1915 to 1929 and 1995 to 2009 periods. Changes in Wi were analyzed in relation to nitrogen input, soil pH, species richness, and functional group composition. Treatments included liming as well as phosphorus and potassium additions with or without ammonium or nitrate fertilizer applications at three levels. Wi increased between 11% and 25% (P < 0.001) in the different treatments between the two periods. None of the fertilizers had a direct effect on the change of Wi (ΔWi). However, soil pH (P < 0.05), species richness (P < 0.01), and percentage grass content (P < 0.01) were significantly related to ΔWi. Grass-dominated, species-poor plots on acidic soils showed the largest ΔWi (+14.7 μmol mol−1). The ΔWi response of these acidic plots was probably related to drought effects resulting from aluminum toxicity on root growth. Our results from the Park Grass Experiment show that Wi in grassland communities consistently increased over a wide range of nutrient inputs, soil pH, and plant community compositions during the last century. PMID:26620525

  9. Last-Century Increases in Intrinsic Water-Use Efficiency of Grassland Communities Have Occurred over a Wide Range of Vegetation Composition, Nutrient Inputs, and Soil pH.

    PubMed

    Köhler, Iris H; Macdonald, Andy J; Schnyder, Hans

    2016-02-01

    Last-century climate change has led to variable increases of the intrinsic water-use efficiency (Wi; the ratio of net CO2 assimilation to stomatal conductance for water vapor) of trees and C3 grassland ecosystems, but the causes of the variability are not well understood. Here, we address putative drivers underlying variable Wi responses in a wide range of grassland communities. Wi was estimated from carbon isotope discrimination in archived herbage samples from 16 contrasting fertilizer treatments in the Park Grass Experiment, Rothamsted, England, for the 1915 to 1929 and 1995 to 2009 periods. Changes in Wi were analyzed in relation to nitrogen input, soil pH, species richness, and functional group composition. Treatments included liming as well as phosphorus and potassium additions with or without ammonium or nitrate fertilizer applications at three levels. Wi increased between 11% and 25% (P < 0.001) in the different treatments between the two periods. None of the fertilizers had a direct effect on the change of Wi (ΔWi). However, soil pH (P < 0.05), species richness (P < 0.01), and percentage grass content (P < 0.01) were significantly related to ΔWi. Grass-dominated, species-poor plots on acidic soils showed the largest ΔWi (+14.7 μmol mol(-1)). The ΔWi response of these acidic plots was probably related to drought effects resulting from aluminum toxicity on root growth. Our results from the Park Grass Experiment show that Wi in grassland communities consistently increased over a wide range of nutrient inputs, soil pH, and plant community compositions during the last century.

  10. Last-Century Increases in Intrinsic Water-Use Efficiency of Grassland Communities Have Occurred over a Wide Range of Vegetation Composition, Nutrient Inputs, and Soil pH.

    PubMed

    Köhler, Iris H; Macdonald, Andy J; Schnyder, Hans

    2016-02-01

    Last-century climate change has led to variable increases of the intrinsic water-use efficiency (Wi; the ratio of net CO2 assimilation to stomatal conductance for water vapor) of trees and C3 grassland ecosystems, but the causes of the variability are not well understood. Here, we address putative drivers underlying variable Wi responses in a wide range of grassland communities. Wi was estimated from carbon isotope discrimination in archived herbage samples from 16 contrasting fertilizer treatments in the Park Grass Experiment, Rothamsted, England, for the 1915 to 1929 and 1995 to 2009 periods. Changes in Wi were analyzed in relation to nitrogen input, soil pH, species richness, and functional group composition. Treatments included liming as well as phosphorus and potassium additions with or without ammonium or nitrate fertilizer applications at three levels. Wi increased between 11% and 25% (P < 0.001) in the different treatments between the two periods. None of the fertilizers had a direct effect on the change of Wi (ΔWi). However, soil pH (P < 0.05), species richness (P < 0.01), and percentage grass content (P < 0.01) were significantly related to ΔWi. Grass-dominated, species-poor plots on acidic soils showed the largest ΔWi (+14.7 μmol mol(-1)). The ΔWi response of these acidic plots was probably related to drought effects resulting from aluminum toxicity on root growth. Our results from the Park Grass Experiment show that Wi in grassland communities consistently increased over a wide range of nutrient inputs, soil pH, and plant community compositions during the last century. PMID:26620525

  11. The role of sugars in integrating environmental signals during the regulation of leaf senescence.

    PubMed

    Wingler, Astrid; Purdy, Sarah; MacLean, Jamie A; Pourtau, Nathalie

    2006-01-01

    Although leaf senescence results in a loss of photosynthetic carbon fixation, the senescence-dependent release of nutrients, especially of nitrogen, is important for the growth of young leaves and for reproduction. Environmental regulation of senescence is therefore a vital factor in the carbon and nitrogen economy of plants. Leaf senescence is a highly plastic trait that is affected by a range of different environmental factors including light, nutrient supply, CO2 concentration, and abiotic and biotic stress. In this review, the focus is on the impact of environmental conditions on sugar accumulation and sugar signalling during senescence. By signalling a high availability of carbon relative to nitrogen in the old leaves, sugar accumulation can trigger leaf senescence. Sugar-induced senescence is therefore particularly important under low nitrogen availability and may also play a role in light signalling. Whether or not sugars are involved in regulating the senescence response of plants to elevated CO2 remains unresolved. Senescence can be delayed or accelerated in elevated CO2 and no clear relationship between sugar accumulation and senescence has been found. Plasticity in the response to environmental factors, such as daylength and sugar accumulation, varies between different Arabidopsis accessions. This natural variation can be exploited to analyse the genetic basis of the regulation of senescence and the consequences for growth and fecundity. Different evolutionary strategies, i.e. early senescence combined with a high reproductive effort or late senescence combined with a low reproductive effort, may be an important adaptation of Arabidopsis accessions to their natural habitat.

  12. Host range validation, molecular identification, and release and establishment of a Chinese biotype of the Asian leaf beetle Lilioceris cheni (Coleoptera:Chrysomelidae:Criocerinae) for control of Dioscorea bulbifera L. in ...

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dioscorea bulbifera, an Asian vine, is invasive in the southeastern USA. It rarely flowers but propagates from potato-like bulbils formed in leaf axils, which persist into the subsequent growing season. Lilioceris cheni Gressitt and Kimoto, a foliage-feeding beetle (Coleoptera: Chrysomelidae: Crio...

  13. Two genetically related begomoviruses causing tomato leaf curl disease in Togo and Nigeria differ in virulence and host range but do not require a betasatellite for induction of disease symptoms.

    PubMed

    Kon, Tatsuya; Gilbertson, Robert L

    2012-01-01

    Tomato leaf curl disease (ToLCD) has emerged as a major constraint on tomato production in some parts of West Africa. In this study, begomoviruses associated with ToLCD in Togo and Nigeria were characterized, as well as a betasatellite associated with the disease in Togo. The genome organization of both viruses is typical of Old World monopartite begomoviruses. Sequence analysis revealed that the begomovirus from Togo is a variant of tomato leaf curl Kumasi virus (ToLCKuV) from Ghana, and it is designated ToLCKuV-[Togo:Pagouda:2006] (ToLCKuV-[TG:Pag:06]). The begomovirus from Nigeria has a recombinant genome, composed of sequences of ToLCKuV (major parent) and a cotton leaf curl Gezira virus (CLCuGV)-like virus, and possesses an unusual non-reiterated replication-associated protein (Rep) binding site. Moreover, because the sequence has <89% identity with those of previously characterized begomoviruses, it is a new species and is designated tomato leaf curl Nigeria virus-[Nigeria:Odogbo:2006] (ToLCNGV-[NG:Odo:06]). The cloned DNAs of ToLCKuV-TG and ToLCNGV were infectious and induced leaf curl symptoms in tomato plants, but ToLCNGV was comparatively more virulent. Both viruses also induced stunted growth and leaf curl symptoms in other solanaceous species (various Nicotiana spp. and Datura stramonium), whereas ToLCNGV but not ToLCKuV-TG induced symptoms in common bean plants. The betasatellite associated with ToLCD in Togo is genetically distinct (i.e., <78% nucleotide sequence identity with previously identified betasatellites) and is designated tomato leaf curl Togo betasatellite-[Togo:Pagouda:2006] (ToLCTGB-[TG:Pag:06]). Replication and systemic spread of ToLCTGB in tomato was mediated by ToLCKuV-TG and ToLCNGV; however, the betasatellite had no effect on disease symptoms induced by either begomovirus. In contrast, ToLCTGB increased symptom severity induced by both viruses in Nicotiana spp. and D. stramonium. Thus, although ToLCTGB increased symptom severity in a

  14. Trends in nutrients

    USGS Publications Warehouse

    Heathwaite, A.L.; Johnes, P.J.; Peters, N.E.

    1996-01-01

    The roles of nitrogen (N) and phosphorus (P) as key nutrients determining the trophic status of water bodies are examined, and evidence reviewed for trends in concentrations of N and P species which occur in freshwaters, primarily in northern temperate environments. Data are reported for water bodies undergoing eutrophication and acidification, especially water bodies receiving increased nitrogen inputs through the atmospheric deposition of nitrogen oxides (NOx). Nutrient loading on groundwaters and surface freshwaters is assessed with respect to causes and rates of (change, relative rates of change for N and P, and implications of change for the future management of lakes, rivers and groundwaters. In particular, the nature and emphasis of studies for N species and P fractions in lakes versus rivers and groundwaters are contrasted. This review paper primarily focuses on results from North America and Europe, particularly for the UK where a wide range of data sets exists. Few nutrient loading data have been published on water bodies in less developed countries; however, some of the available data are presented to provide a global perspective. In general, N and P concentrations have increased dramatically (>20 times background concentrations) in many areas and causes vary considerably, ranging from urbanization to changes in agricultural practices.

  15. Nutrient removal through autumn harvest of Phragmites australis and Thypha latifolia shoots in relation to nutrient loading in a wetland system used for polishing sewage treatment plant effluent.

    PubMed

    Toet, Sylvia; Bouwman, Meike; Cevaal, Annechien; Verhoeven, Jos T A

    2005-01-01

    Phragmites plants and greater reductions in shoot Phragmites biomass because of leaf fall and mass resorption. Nutrient removal by harvesting Phragmites shoots can probably be doubled without a reduction in vitality of the stands by advancing the harvest date to mid-September, which would at least approach the nutrient removal by harvesting Typha shoots in October. Phragmites also may be more profitable in very low-loaded wetland systems because the vigor of Typha stands seemed to be more sensitive to a lower nutrient availability at N and P mass input rates lower than the range indicated.

  16. Tight coupling of leaf area index to canopy nitrogen and phosphorus across heterogeneous tallgrass prairie communities.

    PubMed

    Klodd, Anne E; Nippert, Jesse B; Ratajczak, Zak; Waring, Hazel; Phoenix, Gareth K

    2016-11-01

    Nitrogen (N) and phosphorus (P) are limiting nutrients for many plant communities worldwide. Foliar N and P along with leaf area are among the most important controls on photosynthesis and hence productivity. However, foliar N and P are typically assessed as species level traits, whereas productivity is often measured at the community scale. Here, we compared the community-level traits of leaf area index (LAI) to total foliar nitrogen (TFN) and total foliar phosphorus (TFP) across nearly three orders of magnitude LAI in grazed and ungrazed tallgrass prairie in north-eastern Kansas, USA. LAI was strongly correlated with both TFN and TFP across communities, and also within plant functional types (grass, forb, woody, and sedge) and grazing treatments (bison or cattle, and ungrazed). Across almost the entire range of LAI values and contrasting communities, TFN:TFP ratios indicated co-limitation by N and P in almost all communities; this may further indicate a community scale trend of an optimal N and P allocation per unit leaf area for growth. Previously, results from the arctic showed similar tight relationships between LAI:TFN, suggesting N is supplied to canopies to maximize photosynthesis per unit leaf area. This tight coupling between LAI, N, and P in tallgrass prairie suggests a process of optimal allocation of N and P, wherein LAI remains similarly constrained by N and P despite differences in species composition, grazing, and canopy density. PMID:27561778

  17. Variations in the polarized leaf reflectance of Sorghum bicolor

    NASA Technical Reports Server (NTRS)

    Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

    1987-01-01

    The polarized reflectance factor, Rq, of sorghum (Sorghum bicolor, L.) leaves from field-grown plants was measured in situ in the summers of 1983 and 1984. In 1983, three leaves of two randomly selected plants were measured at 2-week intervals. The value of Rq varied, depending on leaf and day of measurement. Measured values of Rq for the adaxial leaf surface ranged from 16 to 53; for the abaxial leaf surface the values ranged from 28 to 69. In 1984, measurements consisted of repeated observations made on the same leaf at biweekly intervals. The values of Rq from the adaxial leaf surface ranged from 26 to 38. Values of Rq from the abaxial leaf surface increased throughout the season, from 16 to 45. Differences in Rq were attributed to changes in surface details of the leaf.

  18. Patterns in foliar nutrient resorption stoichiometry at multiple scales: controlling factors and ecosystem consequences (Invited)

    NASA Astrophysics Data System (ADS)

    Reed, S.; Cleveland, C. C.; Davidson, E. A.; Townsend, A. R.

    2013-12-01

    During leaf senescence, nutrient rich compounds are transported to other parts of the plant and this 'resorption' recycles nutrients for future growth, reducing losses of potentially limiting nutrients. Variations in leaf chemistry resulting from nutrient resorption also directly affect litter quality, in turn, regulating decomposition rates and soil nutrient availability. Here we investigated stoichiometric patterns of nitrogen (N) and phosphorus (P) resorption efficiency at multiple spatial scales. First, we assembled a global database to explore nutrient resorption among and within biomes and to examine potential relationships between resorption stoichiometry and ecosystem nutrient status. Next, we used a forest regeneration chronosequence in Brazil to assess how resorption stoichiometry linked with a suite of other nutrient cycling measures and with ideas of how nutrient limitation may change over secondary forest regrowth. Finally, we measured N:P resorption ratios of six canopy tree species in a Costa Rican tropical forest. We calculated species-specific resorption ratios and compared them with patterns in leaf litter and topsoil nutrient concentrations. At the global scale, N:P resorption ratios increased with latitude and decreased with mean annual temperature (MAT) and precipitation (MAP; P<0.001 for each). In particular, we observed a notable switch across latitudes: N:P resorption ratios were generally <1 in latitudes <23° and >1 in latitudes >23°. Focusing on tropical sites in our global dataset we found that, despite fewer data and a restricted latitudinal range, a significant relationship between latitude and N:P resorption ratios persisted (P<0.001). In contrast, tropical N:P resorption ratios did not vary with MAT (P=0.965) and the relationship with MAP was only marginally significant (P=0.089). Data suggest that soil type, at least in part, helps explain N:P resorption patterns across tropical latitudes: plants on more weathered soils (Oxisols

  19. Phenological variation of leaf functional traits within species.

    PubMed

    Fajardo, Alex; Siefert, Andrew

    2016-04-01

    A basic assumption of the trait-based approach in plant ecology is that differences in functional trait values are greater between species than within species. We questioned this assumption by assessing (1) the relative extent of inter- and intraspecific leaf trait variation throughout a complete growing season (phenological variation) in a group of deciduous and evergreen woody species, and (2) whether species rankings based on leaf traits were maintained across the growing season. We analysed leaf mass per area (LMA) and leaf nutrient concentrations (C, N, P), including the C:N and N:P ratios. Intraspecific trait variation (ITV) due to phenology was significantly greater than interspecific variation for leaf N concentration on a mass basis (Nm; 68.90 %) and for the leaf C:N ratio (60.60 %), whereas interspecific variation was significantly higher than ITV for LMA (62.30 %) and for leaf C concentration on a mass (Cm) and area (Ca) basis (Cm 70.40 %; Ca 65.30 %). ITV was particularly low for LMA (<20 %). Species rankings were highly modified by phenology for a number of leaf traits (Pm, N:P ratio) but were relatively well conserved throughout the growing season for others (LMA, Nm). Patterns of ITV across the growing season differed significantly between deciduous and evergreen species for all traits except leaf P but did not vary between native and exotic species. Overall, our results show that intraspecific phenological variation in leaf traits may be similar to or greater than interspecific variation and that temporal patterns of ITV vary considerably among traits and species, especially for leaf nutrient concentrations, factors which can potentially affect quantitative interspecific relationships.

  20. Biophysical control of leaf temperature

    NASA Astrophysics Data System (ADS)

    Dong, N.; Prentice, I. C.; Wright, I. J.

    2014-12-01

    In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

  1. Chinese Tallow Trees (Triadica sebifera) from the Invasive Range Outperform Those from the Native Range with an Active Soil Community or Phosphorus Fertilization

    PubMed Central

    Zhang, Ling; Zhang, Yaojun; Wang, Hong; Zou, Jianwen; Siemann, Evan

    2013-01-01

    Two mechanisms that have been proposed to explain success of invasive plants are unusual biotic interactions, such as enemy release or enhanced mutualisms, and increased resource availability. However, while these mechanisms are usually considered separately, both may be involved in successful invasions. Biotic interactions may be positive or negative and may interact with nutritional resources in determining invasion success. In addition, the effects of different nutrients on invasions may vary. Finally, genetic variation in traits between populations located in introduced versus native ranges may be important for biotic interactions and/or resource use. Here, we investigated the roles of soil biota, resource availability, and plant genetic variation using seedlings of Triadica sebifera in an experiment in the native range (China). We manipulated nitrogen (control or 4 g/m2), phosphorus (control or 0.5 g/m2), soil biota (untreated or sterilized field soil), and plant origin (4 populations from the invasive range, 4 populations from the native range) in a full factorial experiment. Phosphorus addition increased root, stem, and leaf masses. Leaf mass and height growth depended on population origin and soil sterilization. Invasive populations had higher leaf mass and growth rates than native populations did in fresh soil but they had lower, comparable leaf mass and growth rates in sterilized soil. Invasive populations had higher growth rates with phosphorus addition but native ones did not. Soil sterilization decreased specific leaf area in both native and exotic populations. Negative effects of soil sterilization suggest that soil pathogens may not be as important as soil mutualists for T. sebifera performance. Moreover, interactive effects of sterilization and origin suggest that invasive T. sebifera may have evolved more beneficial relationships with the soil biota. Overall, seedlings from the invasive range outperformed those from the native range, however, an

  2. Chinese tallow trees (Triadica sebifera) from the invasive range outperform those from the native range with an active soil community or phosphorus fertilization.

    PubMed

    Zhang, Ling; Zhang, Yaojun; Wang, Hong; Zou, Jianwen; Siemann, Evan

    2013-01-01

    Two mechanisms that have been proposed to explain success of invasive plants are unusual biotic interactions, such as enemy release or enhanced mutualisms, and increased resource availability. However, while these mechanisms are usually considered separately, both may be involved in successful invasions. Biotic interactions may be positive or negative and may interact with nutritional resources in determining invasion success. In addition, the effects of different nutrients on invasions may vary. Finally, genetic variation in traits between populations located in introduced versus native ranges may be important for biotic interactions and/or resource use. Here, we investigated the roles of soil biota, resource availability, and plant genetic variation using seedlings of Triadica sebifera in an experiment in the native range (China). We manipulated nitrogen (control or 4 g/m(2)), phosphorus (control or 0.5 g/m(2)), soil biota (untreated or sterilized field soil), and plant origin (4 populations from the invasive range, 4 populations from the native range) in a full factorial experiment. Phosphorus addition increased root, stem, and leaf masses. Leaf mass and height growth depended on population origin and soil sterilization. Invasive populations had higher leaf mass and growth rates than native populations did in fresh soil but they had lower, comparable leaf mass and growth rates in sterilized soil. Invasive populations had higher growth rates with phosphorus addition but native ones did not. Soil sterilization decreased specific leaf area in both native and exotic populations. Negative effects of soil sterilization suggest that soil pathogens may not be as important as soil mutualists for T. sebifera performance. Moreover, interactive effects of sterilization and origin suggest that invasive T. sebifera may have evolved more beneficial relationships with the soil biota. Overall, seedlings from the invasive range outperformed those from the native range, however

  3. Phosphorus as a Colimiting Nutrient with Nitrogen of Birch Plant Growth Across the Arctic

    NASA Astrophysics Data System (ADS)

    Grogan, P.; Zamin, T.; Tremblay, J. P.

    2014-12-01

    Nitrogen is widely cited as the principal growth limiting nutrient for plants in moist, mesic and dry arctic tundra ecosystems. As such, the widespread increases in deciduous shrubs that have been observed across the Arctic as the climate has warmed over the past 30 years, are generally attributed to enhanced nitrogen supply due to temperature-induced increases in soil organic matter decomposition. A recent factorial nitrogen-phosphorus (N x P) chronic addition experiment in the Canadian low Arctic demonstrated that birch shrub growth was as limited by the availability of P as by N. How widespread is this N P colimitation of birch growth, and might variation in the extent of N relative to P limitation be a primary determinant of niche space and therefore species coexistence in birch hummock tundra plant communities? In this talk I will address the following specific questions: a) Can birch leaf N:P be used as a reliable indicator of the relative importance of N and P as growth limiting nutrients? b) What is the pattern of birch leaf N:P ratios across the Arctic? c) Do species that grow alongside birch differ in leaf N:P in ways that suggest differing relative limitation? With the assistance of many colleagues, I collected 150 birch leaf and underlying soil samples from 50 different locations across the North American and European Arctic. I used the factorial experiment described above to test the suitability of leaf N:P ratio as an indicator of relative nutrient limitation for all species in birch hummock tundra communities, and then interpreted the patterns of birch leaf N:P across the Arctic to characterise the spatial extent of NP co-limitation. The results strongly suggest that birch shrub growth is colimited by N and P availability across its range. This conclusion is important because the controls on P availability in soils are as much abiotic (e.g. pH) as biotic (e.g. decomposition), implying that the impacts of climate warming on P supply to plants may be

  4. Insects, infestations and nutrient fluxes

    NASA Astrophysics Data System (ADS)

    Michalzik, B.

    2012-04-01

    Forest ecosystems are characterized by a high temporal and spatial variability in the vertical transfer of energy and matter within the canopy and the soil compartment. The mechanisms and controlling factors behind canopy processes and system-internal transfer dynamics are imperfectly understood at the moment. Seasonal flux diversities and inhomogeneities in throughfall composition have been reported from coniferous and deciduous forests, and in most cases leaf leaching has been considered as principle driver for differences in the amount and quality of nutrients and organic compounds (Tukey and Morgan 1963). Since herbivorous insects and the processes they initiate received less attention in past times, ecologists now emphasize the need for linking biological processes occurring in different ecosystem strata to explain rates and variability of nutrient cycling (Bardgett et al. 1998, Wardle et al. 2004). Consequently, herbivore insects in the canopies of forests are increasingly identified to play an important role for the (re)cycling and availability of nutrients, or, more generally, for the functioning of ecosystems not only in outbreak situations but also at endemic (non-outbreak) density levels (Stadler et al. 2001, Hunter et al. 2003). Before, little attention was paid to insect herbivores when quantifying element and energy fluxes through ecosystems, although the numerous and different functions insects fulfill in ecosystems (e.g. as pollinators, herbivores or detritivores) were unanimously recognized (Schowalter 2000). Amongst the reasons for this restraint was the argument that the total biomass of insects tends to be relatively low compared to the biomass of trees or the pool of soil organic matter (Ohmart et al. 1983). A second argument which was put forward to justify the inferior role of insects in nutrient cycling were the supposed low defoliation losses between 5-10% of the annual leaf biomass, or net primary production, due to insect herbivory under

  5. [Nutrient dynamics in Quercus mongolica leaves at different canopy positions].

    PubMed

    Cheng, Xu-bing; Han, Shi-jie; Zhang, Zhong-hui; Zhou, Yu-mei; Wang, Shu-qi; Wang, Xue-juan

    2011-09-01

    Taking the dominant tree species Quercus mongolica in natural coniferous-broadleaved mixed forest in Changbai Mountains as test object, this paper studied the variations of leaf dry mass per unit area (LMA), leaf carbon (C), nitrogen (N), and phosphorus (P) contents per unit mass and per unit area, as well as the leaf N and P resorption efficiency and use efficiency at upper and lower canopy positions during growth season (from June to October). In the growth season, and at both upper and lower canopy positions, the LMA and leaf C content per unit area had obvious monthly fluctuation, the leaf N and P contents per unit area had the similar monthly variation trend with the leaf N and P contents per unit mass, but the leaf N and P resorption efficiency per unit mass had no significant difference with the leaf N and P resorption efficiency per unit area. The leaf N resorption efficiency and use efficiency were less affected by canopy position, but the leaf P resorption efficiency and use efficiency were higher at upper canopy than at lower canopy. Under the scenario of future climate change, the higher survival and competitive capabilities of Q. mongolica would benefit the nutrient cycling in the test forest ecosystem.

  6. Nutrient-contaminant (Pu) plant accumulation model

    SciTech Connect

    Cowan, C.E.; Jenne, E.A.; Simpson, J.C.; Cataldo, D.A.

    1981-12-01

    A model was developed which simulates the movement and daily accumulation of nutrients and contaminants in crop plants resulting from known physiological processes in the plant. In the model, the daily contaminant accumulation is governed by daily increase in plant biomass derived from photosynthesis and by the specified thermodynamic activity of the bioavailable contaminant species in soil or hydroponic solutin. Total accumulation and resulting concentration in the plant's root, stem and branch, leaf, and reproductive compartments can be simulated any time during the growing season. Parameters were estimated from data on plutonium accumulation in soybeans and the model was calibrated against this same data set. The plutonium distribution in the plant was found to be most sensitive to parameters related to leaf accumulation. Contamination at different times during the growing season resulted in a large change in predicted leaf accumulation but very little change in predicted accumulation in other plant parts except when contamination occurred very late in the growing season.

  7. Analysis of Circadian Leaf Movements.

    PubMed

    Müller, Niels A; Jiménez-Gómez, José M

    2016-01-01

    The circadian clock is a molecular timekeeper that controls a wide variety of biological processes. In plants, clock outputs range from the molecular level, with rhythmic gene expression and metabolite content, to physiological processes such as stomatal conductance or leaf movements. Any of these outputs can be used as markers to monitor the state of the circadian clock. In the model plant Arabidopsis thaliana, much of the current knowledge about the clock has been gained from time course experiments profiling expression of endogenous genes or reporter constructs regulated by the circadian clock. Since these methods require labor-intensive sample preparation or transformation, monitoring leaf movements is an interesting alternative, especially in non-model species and for natural variation studies. Technological improvements both in digital photography and image analysis allow cheap and easy monitoring of circadian leaf movements. In this chapter we present a protocol that uses an autonomous point and shoot camera and free software to monitor circadian leaf movements in tomato. PMID:26867616

  8. RESPONSE OF NUTRIENTS, BIOFILM, AND BENTHIC INSECTS TO SALMON CARCASS ADDITION

    EPA Science Inventory

    Salmon carcass addition to streams is expected to increase stream productivity at multiple trophic levels. This study examined stream nutrient (nitrogen, phosphorus, and carbon), epilithic biofilm (ash-free dry mass and chlorophyll a), leaf-litter decomposition, and macroinverte...

  9. Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia.

    PubMed

    van der Wulp, Simon A; Damar, Ario; Ladwig, Norbert; Hesse, Karl-J

    2016-09-30

    The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377m(3)s(-1) entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174tons and 14 to 60tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics. PMID:27283876

  10. Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia.

    PubMed

    van der Wulp, Simon A; Damar, Ario; Ladwig, Norbert; Hesse, Karl-J

    2016-09-30

    The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377m(3)s(-1) entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174tons and 14 to 60tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics.

  11. High variation in foliage and leaf litter chemistry among 45 tree species of a neotropical rainforest community.

    PubMed

    Hättenschwiler, Stephan; Aeschlimann, Beat; Coûteaux, Marie-Madeleine; Roy, Jacques; Bonal, Damien

    2008-01-01

    Distinct ecosystem level carbon : nitrogen : phosphorus (C : N : P) stoichiometries in forest foliage have been suggested to reflect ecosystem-scale selection for physiological strategies in plant nutrient use. Here, this hypothesis was explored in a nutrient-poor lowland rainforest in French Guiana. Variation in C, N and P concentrations was evaluated in leaf litter and foliage from neighbour trees of 45 different species, and the litter concentrations of major C fractions were also measured. Litter C ranged from 45.3 to 52.4%, litter N varied threefold (0.68-2.01%), and litter P varied seven-fold (0.009-0.062%) among species. Compared with foliage, mean litter N and P concentrations decreased by 30% and 65%, respectively. Accordingly, the range in mass-based N : P shifted from 14 to 55 in foliage to 26 to 105 in litter. Resorption proficiencies indicated maximum P withdrawal in most species, but with a substantial increase in variation in litter P compared with foliage. These data suggest that constrained ecosystem-level C : N : P ratios do not preclude the evolution of highly diversified strategies of nutrient use and conservation among tropical rainforest tree species. The resulting large variation in litter quality will influence stoichiometric constraints within the decomposer food web, with potentially far-ranging consequences on nutrient dynamics and plant-soil feedbacks.

  12. Land use effects on leaf litter breakdown in low-order streams draining a rapidly developing tropical watershed in Puerto Rico.

    PubMed

    Torres, Pedro J; Ramírez, Alonso

    2014-04-01

    Land use has an important role influencing stream ecosystem processes, such as leaf litter breakdown. Here, we assessed rates of leaf litter breakdown in low-order tropical streams draining forest, agriculture, and urban land uses in Puerto Rico. To measure leaf breakdown rates, we placed litter bags made of coarse mesh in nine streams, three for each land use type. At each stream, we measured changes in leaf mass over time, leaf breakdown rates, macroinvertebrate assemblages, and stream physicochemistry. Streams differed in their water physicochemistry, with urban streams showing high values for most variables. Stream physical habitat was evaluated using a visual assessment protocol, which indicated that agricultural and urban streams were more degraded than forested streams. Leaf breakdown rates were fast in all streams (k values ranging 0.006-0.024). Breakdown rates were significantly related to the physical conditions of the stream channel (e.g., visual protocol scores), with fastest rates in forested streams. Invertebrates colonizing leaves were mainly mayflies (Leptophlebiidae, Baetidae, and Caenidae), dipterans (Chironomidae), caddisflies (Polycentropodidae), and beetles (Elmidae and Gyrinidae). Our streams lacked large decapod populations, contrasting with other Puerto Rican streams. We found little evidence for an insect effect on leaf breakdown. Results suggest that land use is an important factor affecting leaf litter processing in streams. In contrast to studies in temperate regions, we found little evidence for a positive nutrient related effect of agricultural land use on decomposition rates. Changes in the physical characteristics of streams appear to be the main drivers behind observed decomposition patterns.

  13. Nutrient limitation and stoichiometry of carnivorous plants.

    PubMed

    Ellison, A M

    2006-11-01

    The cost-benefit model for the evolution of carnivorous plants posits a trade-off between photosynthetic costs associated with carnivorous structures and photosynthetic benefits accrued through additional nutrient acquisition. The model predicts that carnivory is expected to evolve if its marginal benefits exceed its marginal costs. Further, the model predicts that when nutrients are scarce but neither light nor water is limiting, carnivorous plants should have an energetic advantage in competition with non-carnivorous plants. Since the publication of the cost-benefit model over 20 years ago, marginal photosynthetic costs of carnivory have been demonstrated but marginal photosynthetic benefits have not. A review of published data and results of ongoing research show that nitrogen, phosphorus, and potassium often (co-)limit growth of carnivorous plants and that photosynthetic nutrient use efficiency is 20 - 50 % of that of non-carnivorous plants. Assessments of stoichiometric relationships among limiting nutrients, scaling of leaf mass with photosynthesis and nutrient content, and photosynthetic nutrient use efficiency all suggest that carnivorous plants are at an energetic disadvantage relative to non-carnivorous plants in similar habitats. Overall, current data support some of the predictions of the cost-benefit model, fail to support others, and still others remain untested and merit future research. Rather than being an optimal solution to an adaptive problem, botanical carnivory may represent a set of limited responses constrained by both phylogenetic history and environmental stress.

  14. Nutrient limitation and stoichiometry of carnivorous plants.

    PubMed

    Ellison, A M

    2006-11-01

    The cost-benefit model for the evolution of carnivorous plants posits a trade-off between photosynthetic costs associated with carnivorous structures and photosynthetic benefits accrued through additional nutrient acquisition. The model predicts that carnivory is expected to evolve if its marginal benefits exceed its marginal costs. Further, the model predicts that when nutrients are scarce but neither light nor water is limiting, carnivorous plants should have an energetic advantage in competition with non-carnivorous plants. Since the publication of the cost-benefit model over 20 years ago, marginal photosynthetic costs of carnivory have been demonstrated but marginal photosynthetic benefits have not. A review of published data and results of ongoing research show that nitrogen, phosphorus, and potassium often (co-)limit growth of carnivorous plants and that photosynthetic nutrient use efficiency is 20 - 50 % of that of non-carnivorous plants. Assessments of stoichiometric relationships among limiting nutrients, scaling of leaf mass with photosynthesis and nutrient content, and photosynthetic nutrient use efficiency all suggest that carnivorous plants are at an energetic disadvantage relative to non-carnivorous plants in similar habitats. Overall, current data support some of the predictions of the cost-benefit model, fail to support others, and still others remain untested and merit future research. Rather than being an optimal solution to an adaptive problem, botanical carnivory may represent a set of limited responses constrained by both phylogenetic history and environmental stress. PMID:17203429

  15. Intestinal sensing of nutrients.

    PubMed

    Tolhurst, Gwen; Reimann, Frank; Gribble, Fiona M

    2012-01-01

    Ingestion of a meal triggers a range of physiological responses both within and outside the gut, and results in the remote modulation of appetite and glucose homeostasis. Luminal contents are sensed by specialised chemosensitive cells scattered throughout the intestinal epithelium. These enteroendocrine and tuft cells make direct contact with the gut lumen and release a range of chemical mediators, which can either act in a paracrine fashion interacting with neighbouring cells and nerve endings or as classical circulating hormones. At the molecular level, the chemosensory machinery involves multiple and complex signalling pathways including activation of G-protein-coupled receptors and solute carrier transporters. This chapter will discuss our current knowledge of the molecular mechanisms underlying intestinal chemosensation with a particular focus on the relatively well-characterised nutrient-triggered secretion from the enteroendocrine system. PMID:22249821

  16. Diagnosis & Correction of Soil Nutrient Limitations in Intensively managed southern pine forests

    SciTech Connect

    University of Florida

    2002-10-25

    Forest productivity is one manner to sequester carbon and it is a renewable energy source. Likewise, efficient use of fertilization can be a significant energy savings. To date, site-specific use of fertilization for the purpose of maximizing forest productivity has not been well developed. Site evaluation of nutrient deficiencies is primarily based on empirical approaches to soil testing and plot fertilizer tests with little consideration for soil water regimes and contributing site factors. This project uses mass flow diffusion theory in a modeling context, combined with process level knowledge of soil chemistry, to evaluate nutrient bioavailability to fast-growing juvenile forest stands growing on coastal plain Spodosols of the southeastern U.S. The model is not soil or site specific and should be useful for a wide range of soil management/nutrient management conditions. In order to use the model, field data of fast-growing southern pine needed to be measured and used in the validation of the model. The field aspect of the study was mainly to provide data that could be used to verify the model. However, we learned much about the growth and development of fast growing loblolly. Carbon allocation patterns, root shoot relationships and leaf area root relationships proved to be new, important information. The Project Objectives were to: (1) Develop a mechanistic nutrient management model based on the COMP8 uptake model. (2) Collect field data that could be used to verify and test the model. (3) Model testing.

  17. Root Nutrient Foraging1

    PubMed Central

    Giehl, Ricardo F.H.; von Wirén, Nicolaus

    2014-01-01

    During a plant's lifecycle, the availability of nutrients in the soil is mostly heterogeneous in space and time. Plants are able to adapt to nutrient shortage or localized nutrient availability by altering their root system architecture to efficiently explore soil zones containing the limited nutrient. It has been shown that the deficiency of different nutrients induces root architectural and morphological changes that are, at least to some extent, nutrient specific. Here, we highlight what is known about the importance of individual root system components for nutrient acquisition and how developmental and physiological responses can be coupled to increase nutrient foraging by roots. In addition, we review prominent molecular mechanisms involved in altering the root system in response to local nutrient availability or to the plant's nutritional status. PMID:25082891

  18. Effect of temperature and nutrients on the growth and development of seedlings of an invasive plant

    PubMed Central

    Skálová, Hana; Moravcová, Lenka; Dixon, Anthony F. G.; Kindlmann, P.; Pyšek, Petr

    2015-01-01

    Plant species distributions are determined by the response of populations to regional climates; however, little is known about how alien plants that arrive in central Europe from climatically warmer regions cope with the temperature conditions at the early stage of population development. Ambrosia artemisiifolia (common ragweed) is an invasive annual plant causing considerable health and economic problems in Europe. Although climate-based models predict that the whole of the Czech Republic is climatically suitable for this species, it is confined to the warmest regions. To determine the factors possibly responsible for its restricted occurrence, we investigated the effects of temperature and nutrient availability on its seedlings. The plants were cultivated at one of seven temperature regimes ranging from 10 to 34 °C, combined with three nutrient levels. The data on the rate of leaf development were used to calculate the lower developmental threshold (LDT, the temperature, in °C, below which development ceases), the sum of effective temperatures (SET, the amount of heat needed to complete a developmental stage measured in degree days above LDT) and width of the thermal window. The rate of development decreased with decrease in temperature and nutrient supply. Besides this, the decrease in the availability of nutrients resulted in decreased LDT, increased SET and wider thermal window. The dependence of LDT and SET on the availability of nutrients contradicts the concept that thermal constants do not vary. Our results highlight temperature as the main determinant of common ragweed's distribution and identify nutrient availability as a factor that results in the realized niche being smaller than the fundamental niche; both of these need to be taken into account when predicting the future spread of A. artemisiifolia. PMID:25926326

  19. Effect of temperature and nutrients on the growth and development of seedlings of an invasive plant.

    PubMed

    Skálová, Hana; Moravcová, Lenka; Dixon, Anthony F G; Kindlmann, P; Pyšek, Petr

    2015-04-28

    Plant species distributions are determined by the response of populations to regional climates; however, little is known about how alien plants that arrive in central Europe from climatically warmer regions cope with the temperature conditions at the early stage of population development. Ambrosia artemisiifolia (common ragweed) is an invasive annual plant causing considerable health and economic problems in Europe. Although climate-based models predict that the whole of the Czech Republic is climatically suitable for this species, it is confined to the warmest regions. To determine the factors possibly responsible for its restricted occurrence, we investigated the effects of temperature and nutrient availability on its seedlings. The plants were cultivated at one of seven temperature regimes ranging from 10 to 34 °C, combined with three nutrient levels. The data on the rate of leaf development were used to calculate the lower developmental threshold (LDT, the temperature, in °C, below which development ceases), the sum of effective temperatures (SET, the amount of heat needed to complete a developmental stage measured in degree days above LDT) and width of the thermal window. The rate of development decreased with decrease in temperature and nutrient supply. Besides this, the decrease in the availability of nutrients resulted in decreased LDT, increased SET and wider thermal window. The dependence of LDT and SET on the availability of nutrients contradicts the concept that thermal constants do not vary. Our results highlight temperature as the main determinant of common ragweed's distribution and identify nutrient availability as a factor that results in the realized niche being smaller than the fundamental niche; both of these need to be taken into account when predicting the future spread of A. artemisiifolia.

  20. [Determination of nutrients in 7 species of desert plants for raising livestock in inner Mongolia].

    PubMed

    Liu, Ying; Feng, Jin-chao

    2008-09-01

    In order to accumulate the foundational information about the nutrients related to 7 species of desert plants, chemical and instrumental methods for determination were used and quantitative results were obtained as follows (%, in dry mass): calcium 0.73-3.89, phosphorus 0.043-0.34, selenium 0.026-2.8, protein 3.38-13.92, lipid 3.97-15.03, total sugar 14.89-35.78, ash 0.61-14.33, medium washing fiber 26.66-79.72, and acid washing fiber 27.03-69.01. Among the 7 species of desert plants, the total content of amino acid in the leaf and caudex ranges from 2.30% to 11.26%. Apart from Elaeagnus angusti folia, the ratios of the calcium and phosphorus both in the leaves and caudexes of the rest 6 kinds of desert plants are higher than those in the leaf powder and caudex powder of clover blossom. The selenium content is greater than the usual amount in plants; the protein content reaches the level of excellent grains; the lipid contents in leaf, caudex and whole plant are higher than those in straws of corn and wheat; the leaves have more total sugar than the caudex and the whole plant, and the high level of ash content exists in the 7 species of desert plants; and the medium washing fiber content in leaf of those plants is lower than that in clover blossom leaf powder, which is opposite to the content in caudex. Except for Haloxylon ammodendron, the acid washing fiber content in caudexes is beyond that in the caudex powder of the clover blossom. As is indicated in the data above, the 7 species of desert plants not only do meet the demands of raising livestock, but also are ideal feeding resources for the husbandry development in sandy areas. PMID:19093584

  1. The energetic and carbon economic origins of leaf thermoregulation.

    PubMed

    Michaletz, Sean T; Weiser, Michael D; McDowell, Nate G; Zhou, Jizhong; Kaspari, Michael; Helliker, Brent R; Enquist, Brian J

    2016-08-22

    Leaf thermoregulation has been documented in a handful of studies, but the generality and origins of this pattern are unclear. We suggest that leaf thermoregulation is widespread in both space and time, and originates from the optimization of leaf traits to maximize leaf carbon gain across and within variable environments. Here we use global data for leaf temperatures, traits and photosynthesis to evaluate predictions from a novel theory of thermoregulation that synthesizes energy budget and carbon economics theories. Our results reveal that variation in leaf temperatures and physiological performance are tightly linked to leaf traits and carbon economics. The theory, parameterized with global averaged leaf traits and microclimate, predicts a moderate level of leaf thermoregulation across a broad air temperature gradient. These predictions are supported by independent data for diverse taxa spanning a global air temperature range of ∼60 °C. Moreover, our theory predicts that net carbon assimilation can be maximized by means of a trade-off between leaf thermal stability and photosynthetic stability. This prediction is supported by globally distributed data for leaf thermal and photosynthetic traits. Our results demonstrate that the temperatures of plant tissues, and not just air, are vital to developing more accurate Earth system models.

  2. The energetic and carbon economic origins of leaf thermoregulation.

    PubMed

    Michaletz, Sean T; Weiser, Michael D; McDowell, Nate G; Zhou, Jizhong; Kaspari, Michael; Helliker, Brent R; Enquist, Brian J

    2016-01-01

    Leaf thermoregulation has been documented in a handful of studies, but the generality and origins of this pattern are unclear. We suggest that leaf thermoregulation is widespread in both space and time, and originates from the optimization of leaf traits to maximize leaf carbon gain across and within variable environments. Here we use global data for leaf temperatures, traits and photosynthesis to evaluate predictions from a novel theory of thermoregulation that synthesizes energy budget and carbon economics theories. Our results reveal that variation in leaf temperatures and physiological performance are tightly linked to leaf traits and carbon economics. The theory, parameterized with global averaged leaf traits and microclimate, predicts a moderate level of leaf thermoregulation across a broad air temperature gradient. These predictions are supported by independent data for diverse taxa spanning a global air temperature range of ∼60 °C. Moreover, our theory predicts that net carbon assimilation can be maximized by means of a trade-off between leaf thermal stability and photosynthetic stability. This prediction is supported by globally distributed data for leaf thermal and photosynthetic traits. Our results demonstrate that the temperatures of plant tissues, and not just air, are vital to developing more accurate Earth system models. PMID:27548589

  3. Variations of leaf N, P concentrations in shrubland biomes across northern China: phylogeny, climate and soil

    NASA Astrophysics Data System (ADS)

    Yang, X.; Chi, X.; Ji, C.; Liu, H.; Ma, W.; Mohhammat, A.; Shi, Z.; Wang, X.; Yu, S.; Yue, M.; Tang, Z.

    2015-11-01

    Concentrations of leaf nitrogen (N) and phosphorus (P) are key leaf traits in ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on trees and grasses, leaving the knowledge gap for the stoichiometric patterns of shrubs. In this study, we explored the intra- and interspecific variations of leaf N and P concentration in relation to climate, soil property and evolutionary history based on 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China expanding 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. The results showed that leaf N concentration decreased with precipitation, leaf P concentration decreased with temperature and increased with precipitation and soil P concentration. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentration was less conserved than leaf N concentration. At community level, climates explained more interspecific, while soil nutrient explained more intraspecific, variation of leaf nutrient concentrations. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits.

  4. Chloride regulates leaf cell size and water relations in tobacco plants.

    PubMed

    Franco-Navarro, Juan D; Brumós, Javier; Rosales, Miguel A; Cubero-Font, Paloma; Talón, Manuel; Colmenero-Flores, José M

    2016-02-01

    Chloride (Cl(-)) is a micronutrient that accumulates to macronutrient levels since it is normally available in nature and actively taken up by higher plants. Besides a role as an unspecific cell osmoticum, no clear biological roles have been explicitly associated with Cl(-) when accumulated to macronutrient concentrations. To address this question, the glycophyte tobacco (Nicotiana tabacum L. var. Habana) has been treated with a basal nutrient solution supplemented with one of three salt combinations containing the same cationic balance: Cl(-)-based (CL), nitrate-based (N), and sulphate+phosphate-based (SP) treatments. Under non-saline conditions (up to 5 mM Cl(-)) and no water limitation, Cl(-) specifically stimulated higher leaf cell size and led to a moderate increase of plant fresh and dry biomass mainly due to higher shoot expansion. When applied in the 1-5 mM range, Cl(-) played specific roles in regulating leaf osmotic potential and turgor, allowing plants to improve leaf water balance parameters. In addition, Cl(-) also altered water relations at the whole-plant level through reduction of plant transpiration. This was a consequence of a lower stomatal conductance, which resulted in lower water loss and greater photosynthetic and integrated water-use efficiency. In contrast to Cl(-), these effects were not observed for essential anionic macronutrients such as nitrate, sulphate, and phosphate. We propose that the abundant uptake and accumulation of Cl(-) responds to adaptive functions improving water homeostasis in higher plants.

  5. Chloride regulates leaf cell size and water relations in tobacco plants

    PubMed Central

    Franco-Navarro, Juan D.; Brumós, Javier; Rosales, Miguel A.; Cubero-Font, Paloma; Talón, Manuel; Colmenero-Flores, José M.

    2016-01-01

    Chloride (Cl–) is a micronutrient that accumulates to macronutrient levels since it is normally available in nature and actively taken up by higher plants. Besides a role as an unspecific cell osmoticum, no clear biological roles have been explicitly associated with Cl– when accumulated to macronutrient concentrations. To address this question, the glycophyte tobacco (Nicotiana tabacum L. var. Habana) has been treated with a basal nutrient solution supplemented with one of three salt combinations containing the same cationic balance: Cl–-based (CL), nitrate-based (N), and sulphate+phosphate-based (SP) treatments. Under non-saline conditions (up to 5mM Cl–) and no water limitation, Cl– specifically stimulated higher leaf cell size and led to a moderate increase of plant fresh and dry biomass mainly due to higher shoot expansion. When applied in the 1–5mM range, Cl– played specific roles in regulating leaf osmotic potential and turgor, allowing plants to improve leaf water balance parameters. In addition, Cl– also altered water relations at the whole-plant level through reduction of plant transpiration. This was a consequence of a lower stomatal conductance, which resulted in lower water loss and greater photosynthetic and integrated water-use efficiency. In contrast to Cl–, these effects were not observed for essential anionic macronutrients such as nitrate, sulphate, and phosphate. We propose that the abundant uptake and accumulation of Cl– responds to adaptive functions improving water homeostasis in higher plants. PMID:26602947

  6. Causes and consequences of variation in leaf mass per area (LMA): a meta-analysis.

    PubMed

    Poorter, Hendrik; Niinemets, Ulo; Poorter, Lourens; Wright, Ian J; Villar, Rafael

    2009-01-01

    Here, we analysed a wide range of literature data on the leaf dry mass per unit area (LMA). In nature, LMA varies more than 100-fold among species. Part of this variation (c. 35%) can be ascribed to differences between functional groups, with evergreen species having the highest LMA, but most of the variation is within groups or biomes. When grown in the same controlled environment, leaf succulents and woody evergreen, perennial or slow-growing species have inherently high LMA. Within most of the functional groups studied, high-LMA species show higher leaf tissue densities. However, differences between evergreen and deciduous species result from larger volumes per area (thickness). Response curves constructed from experiments under controlled conditions showed that LMA varied strongly with light, temperature and submergence, moderately with CO2 concentration and nutrient and water stress, and marginally under most other conditions. Functional groups differed in the plasticity of LMA to these gradients. The physiological regulation is still unclear, but the consequences of variation in LMA and the suite of traits interconnected with it are strong. This trait complex is an important factor determining the fitness of species in their environment and affects various ecosystem processes.

  7. Nutrient Density Scores.

    ERIC Educational Resources Information Center

    Dickinson, Annette; Thompson, William T.

    1979-01-01

    Announces a nutrient density food scoring system called the Index of Nutritional Quality (INQ). It expresses the ratio between the percent RDA of a nutrient and the percent daily allowance of calories in a food. (Author/SA)

  8. Biometamaterials: Black Ultrathin Gold Film Fabricated on Lotus Leaf

    PubMed Central

    Ebihara, Yuusuke; Ota, Ryoichi; Noriki, Takahiro; Shimojo, Masayuki; Kajikawa, Kotaro

    2015-01-01

    We report on a black metamaterial of gold fabricated on a lotus leaf that was used as a template. In spite of the extremely thin gold coating (10-nm thick) on the lotus leaf, the surface shows reflectivity below 0.01 over the entire visible spectral range. Finite-difference time-domain (FDTD) calculations suggest that the low reflectivity stems from the secondary structures on the lotus leaf, where randomly oriented nanorods are distributed. PMID:26530514

  9. The altitudinal patterns of leaf C∶N∶P stoichiometry are regulated by plant growth form, climate and soil on Changbai Mountain, China.

    PubMed

    Zhao, Ning; He, Nianpeng; Wang, Qiufeng; Zhang, Xinyu; Wang, Ruili; Xu, Zhiwei; Yu, Guirui

    2014-01-01

    Understanding the geographic patterns and potential drivers of leaf stoichiometry is critical for modelling the nutrient fluxes of ecosystems and to predict the responses of ecosystems to global changes. This study aimed to explore the altitudinal patterns and potential drivers of leaf C∶N∶P stoichiometry. We measured the concentrations of leaf C, N and P in 175 plant species as well as soil nutrient concentrations along an altitudinal transect (500-2300 m) on the northern slope of Changbai Mountain, China to explore the response of leaf C∶N∶P stoichiometry to plant growth form (PGF), climate and soil. Leaf C, N, P and C∶N∶P ratios showed significant altitudinal trends. In general, leaf C and C∶N∶P ratios increased while leaf N and P decreased with elevation. Woody and herbaceous species showed different responses to altitudinal gradients. Trees had the largest variation in leaf C, C∶N and C∶P ratios, while herbs showed the largest variation in leaf N, P and N∶P ratio. PGF, climate and soil jointly regulated leaf stoichiometry, explaining 17.6% to 52.1% of the variation in the six leaf stoichiometric traits. PGF was more important in explaining leaf stoichiometry variation than soil and climate. Our findings will help to elucidate the altitudinal patterns of leaf stoichiometry and to model ecosystem nutrient cycling.

  10. Leaf volatile emissions of Betula pendula during autumn coloration and leaf fall.

    PubMed

    Holopainen, Jarmo K; Heijari, Juha; Oksanen, Elina; Alessio, Giorgio A

    2010-10-01

    Deciduous trees remobilize the nitrogen in leaves during the process of autumn coloration, thus providing a high quality food source for aphids preparing to lay over-wintering eggs. It has been suggested that aphids may use volatile organic compounds (VOCs) to: (a) select leaves where nutrient remobilization has started and induced defenses are reduced; and (b) detect the time of leaf abscission. We analyzed VOCs emitted by the foliage of Betula pendula Roth. during autumn coloration and from leaf litter just after leaf fall. We tested the hypothesis that costly, photosynthesis-related terpenes and other herbivore-induced VOCs related to attraction of aphid parasitoids and predators are reduced during the coloration process. We also investigated if the VOC emission profile of abscising leaves is different from that of early stage yellowing leaves. Enemy-luring compounds (E)-β-ocimene, linalool, and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were emitted only from the green foliage. Methyl salicylate (MeSa), known to recruit predatory bugs and attract migrant aphids, was emitted until the first stage of color change. Cis-3-hexenol, an indicator of cellular disintegration, became dominant in the emissions from abscising leaves and from fresh leaf litter. We discuss the ecological significance of the observed changes in birch leaf VOC profiles during the process of autumn senescence.

  11. Autophagy, plant senescence, and nutrient recycling.

    PubMed

    Avila-Ospina, Liliana; Moison, Michael; Yoshimoto, Kohki; Masclaux-Daubresse, Céline

    2014-07-01

    Large numbers of publications have appeared over the last few years, dealing with the molecular details of the regulation and process of the autophagy machinery in animals, plants, and unicellular eukaryotic organisms. This strong interest is caused by the fact that the autophagic process is involved in the adaptation of organisms to their environment and to stressful conditions, thereby contributing to cell and organism survival and longevity. In plants, as in other eukaryotes, autophagy is associated with longevity as mutants display early and strong leaf senescence symptoms, however, the exact role of autophagy as a pro-survival or pro-death process is unclear. Recently, evidence that autophagy participates in nitrogen remobilization has been provided, but the duality of the role of autophagy in leaf longevity and/or nutrient recycling through cell component catabolism remains. This review aims to give an overview of leaf senescence-associated processes from the physiological point of view and to discuss relationships between nutrient recycling, proteolysis, and autophagy. The dual role of autophagy as a pro-survival or pro-death process is discussed.

  12. Leaf morphological and anatomical traits from tropical to temperate coniferous forests: Mechanisms and influencing factors

    PubMed Central

    Tian, Miao; Yu, Guirui; He, Nianpeng; Hou, Jihua

    2016-01-01

    Leaf traits may reflect the adaptation mechanisms of plants to the environment. In this study, we investigated leaf morphological and anatomical traits in nine cold-temperate to tropical forests along a 4,200-km transect to test how they vary across latitudinal gradients. The results showed that leaf dry weight decreased (P < 0.05), while specific leaf area (SLA) increased (P < 0.05) with increasing latitude. Stomatal length and stomatal density did not change significantly, while stomatal pore area index increased (P < 0.05) with increasing latitude. The palisade-leaf mesophyll thickness ratio increased (P < 0.01), while the spongy-leaf mesophyll thickness ratio decreased, with increasing latitude (P < 0.01). Climate and leaf nutrients were the main factors that regulated leaf morphological and anatomical traits. Furthermore, we identified positive correlations between leaf area and leaf dry weight, leaf thickness and palisade mesophyll thickness, but negative correlations between stomatal length and stomatal density (all P < 0.01). The observed negative correlations represented the adaptive mechanisms of leaves through their morphological and anatomical traits. These findings provided new insights into the responses of leaf morphological and anatomical traits to climate changes and important parameters for future model optimization. PMID:26796339

  13. Leaf morphological and anatomical traits from tropical to temperate coniferous forests: Mechanisms and influencing factors.

    PubMed

    Tian, Miao; Yu, Guirui; He, Nianpeng; Hou, Jihua

    2016-01-22

    Leaf traits may reflect the adaptation mechanisms of plants to the environment. In this study, we investigated leaf morphological and anatomical traits in nine cold-temperate to tropical forests along a 4,200-km transect to test how they vary across latitudinal gradients. The results showed that leaf dry weight decreased (P < 0.05), while specific leaf area (SLA) increased (P < 0.05) with increasing latitude. Stomatal length and stomatal density did not change significantly, while stomatal pore area index increased (P < 0.05) with increasing latitude. The palisade-leaf mesophyll thickness ratio increased (P < 0.01), while the spongy-leaf mesophyll thickness ratio decreased, with increasing latitude (P < 0.01). Climate and leaf nutrients were the main factors that regulated leaf morphological and anatomical traits. Furthermore, we identified positive correlations between leaf area and leaf dry weight, leaf thickness and palisade mesophyll thickness, but negative correlations between stomatal length and stomatal density (all P < 0.01). The observed negative correlations represented the adaptive mechanisms of leaves through their morphological and anatomical traits. These findings provided new insights into the responses of leaf morphological and anatomical traits to climate changes and important parameters for future model optimization.

  14. Proteome data associated with the leaf senescence in Glycine max.

    PubMed

    Gupta, Ravi; Lee, Su Ji; Min, Cheol Woo; Kim, So Wun; Park, Ki-Hun; Bae, Dong-Won; Lee, Byong Won; Agrawal, Ganesh Kumar; Rakwal, Randeep; Kim, Sun Tae

    2016-12-01

    The data presented in this article are associated with the article "Coupling of gel-based 2-DE and 1-DE shotgun proteomics approaches to dig deep into the leaf senescence proteome of Glycine max" (R. Gupta, S.J. Lee, C.W. Min, S.W. Kim, K.-H. Park, D.-W. Bae, et al., 2016) [1]. Leaf senescence is one of the important aspects of the life cycle of a plant that leads to the recycling of nutrients from source to sink cells. To understand the leaf senescence-associated proteins, we used a combination of gel-based 2-DE and 1-DE shotgun proteomic approaches. Here, we display the 2-DE, Mass spectrometry, and Gene ontology data related with the leaf senescence in soybean [1]. PMID:27631020

  15. Proteome data associated with the leaf senescence in Glycine max.

    PubMed

    Gupta, Ravi; Lee, Su Ji; Min, Cheol Woo; Kim, So Wun; Park, Ki-Hun; Bae, Dong-Won; Lee, Byong Won; Agrawal, Ganesh Kumar; Rakwal, Randeep; Kim, Sun Tae

    2016-12-01

    The data presented in this article are associated with the article "Coupling of gel-based 2-DE and 1-DE shotgun proteomics approaches to dig deep into the leaf senescence proteome of Glycine max" (R. Gupta, S.J. Lee, C.W. Min, S.W. Kim, K.-H. Park, D.-W. Bae, et al., 2016) [1]. Leaf senescence is one of the important aspects of the life cycle of a plant that leads to the recycling of nutrients from source to sink cells. To understand the leaf senescence-associated proteins, we used a combination of gel-based 2-DE and 1-DE shotgun proteomic approaches. Here, we display the 2-DE, Mass spectrometry, and Gene ontology data related with the leaf senescence in soybean [1].

  16. Automated rice leaf disease detection using color image analysis

    NASA Astrophysics Data System (ADS)

    Pugoy, Reinald Adrian D. L.; Mariano, Vladimir Y.

    2011-06-01

    In rice-related institutions such as the International Rice Research Institute, assessing the health condition of a rice plant through its leaves, which is usually done as a manual eyeball exercise, is important to come up with good nutrient and disease management strategies. In this paper, an automated system that can detect diseases present in a rice leaf using color image analysis is presented. In the system, the outlier region is first obtained from a rice leaf image to be tested using histogram intersection between the test and healthy rice leaf images. Upon obtaining the outlier, it is then subjected to a threshold-based K-means clustering algorithm to group related regions into clusters. Then, these clusters are subjected to further analysis to finally determine the suspected diseases of the rice leaf.

  17. Wheat leaf photosynthesis loss due to leaf rust, with respect to lesion development and leaf nitrogen status.

    PubMed

    Robert, Corinne; Bancal, Marie-Odile; Ney, Bertrand; Lannou, Christian

    2005-01-01

    In wheat (Triticum aestivum cv. Soissons) plants grown under three different fertilisation treatments, we quantified the effect of leaf rust (Puccinia triticina) on flag leaf photosynthesis during the whole sporulation period. Bastiaans' model: Y = (1 - x)beta was used to characterize the relationship between relative leaf photosynthesis (Y) and disease severity (x). The evolution of the different types of symptoms induced by the pathogen (sporulating, chlorotic and necrosed tissues) was evaluated using image analysis. The beta-values varied from 2 to 11, 1.4-2, and 0.8-1 during the sporulation period, when considering the proportion of sporulating, sporulating + necrotic, and total diseased area, respectively. Leaf nitrogen (N) content did not change the effect of the disease on host photosynthesis. We concluded that leaf rust has no global effect on the photosynthesis of the symptomless parts of the leaves and that the large range in the quantification of leaf rust effect on the host, which is found in the literature, can be accounted for by considering the different symptom types. We discuss how our results could improve disease assessments and damage prediction in a wheat crop.

  18. Galling by Rhopalomyia solidaginis alters Solidago altissima architecture and litter nutrient dynamics in an old-field ecosystem

    SciTech Connect

    Crutsinger, Greg; Habenicht, Melissa N; Classen, Aimee T; Schweitzer, Jennifer A; Sanders, Dr. Nathan James

    2008-01-01

    Plant-insect interactions can alter ecosystem processes, especially if the insects modify plant architecture, quality, or the quantity of leaf litter inputs. In this study, we investigated the interactions between the gall midge Rhopalomyia solidaginis and tall goldenrod, Solidago altissima, to quantify the degree to which the midge alters plant architecture and how the galls affect rates of litter decomposition and nutrient release in an old-field ecosystem. R. solidaginis commonly leads to the formation of a distinct apical rosette gall on S. altissima and approximately 15% of the ramets in a S. altissima patch were galled (range: 3-34%). Aboveground biomass of galled ramets was 60% higher and the leaf area density was four times greater on galled leaf tissue relative to the portions of the plant that were not affected by the gall. Overall decomposition rate constants did not differ between galled and ungalled leaf litter. However, leaf-litter mass loss was lower in galled litter relative to ungalled litter, which was likely driven by modest differences in initial litter chemistry; this effect diminished after 12 weeks of decomposition in the field. The proportion of N remaining was always higher in galled litter than in ungalled litter at each collection date indicating differential release of nitrogen in galled leaf litter. Several studies have shown that plant-insect interactions on woody species can alter ecosystem processes by affecting the quality or quantity of litter inputs. Our results illustrate how plant-insect interactions in an herbaceous species can affect ecosystem processes by altering the quality and quantity of litter inputs. Given that S. altissima dominates fields and roadsides and that R. solidaginis galls are highly abundant throughout eastern North America, these interactions are likely to be important for both the structure and function of old-field ecosystems.

  19. Leaf growth is conformal

    NASA Astrophysics Data System (ADS)

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I.; Boudaoud, Arezki

    2016-10-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour.

  20. Leaf growth is conformal.

    PubMed

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I; Boudaoud, Arezki

    2016-01-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour. PMID:27597439

  1. Yeasts colonizing the leaf surfaces.

    PubMed

    Sláviková, Elena; Vadkertiová, Renata; Vránová, Dana

    2007-08-01

    The yeasts were isolated from the leaf surfaces of ten species of trees. The study site was a forest park (Zelezná Studnicka) of the Small Carpathians mountain range. One hundred and thirty seven yeast strains belonging to 13 genera were isolated from 320 samples of leaves and needles. Seventeen yeast species were isolated, but only seven occurred regularly: Aureobasidium pullulans, Cryptococcus laurentii, Pichia anomala, Metschnikowia pulcherrima, Saccharomyces sp., Lachancea thermotolerans, and Rhodotorula glutinis. The remaining species were isolated from the leaves and needles of three or less tree species. A. pullulans, Cr. laurentii, and P. anomala were the most frequently found species and they occurred on leaves and needles of all ten tree species. Saccharomyces sp. occurred in leaf samples collected from eight kinds of trees. M. pulcherrima and L. thermotolerans were found in samples collected from six species of trees. Both these species occurred almost always on the leaves of deciduous trees. Rh. glutinis was the most frequently isolated carotenoids producing species. We have found out that the ascomycetous and basidiomycetous species were present in the leaf samples in approximately equal frequency, contrary to the soil samples taken from this forest park, where the ascomycetous species were found rarely.

  2. Spectroscopic determination of leaf nutritional, morpholgical, and metabolic traits

    NASA Astrophysics Data System (ADS)

    Serbin, Shawn P.

    Terrestrial ecosystems, particularly forests, play an important role in the global carbon and water cycles. Remote sensing observations are invaluable to the study of vegetation patterning, ecosystem functioning, and dynamics. This research examined the relationships between leaf optical properties and important leaf structural, biochemical, and metabolic traits that describe the photosynthetic capacity, recalcitrance, and nutrient dynamics of plant canopies. This was done utilizing leaf-level reflectance spectroscopy in conjunction with traditional chemometric statistical techniques designed to handle high-dimensionality data, specifically partial least-squares regression (PLSR). A suite of leaf biochemical and morphological traits were estimated with high accuracy and precision using measurements of dried and ground leaf material with a portable spectroradiometer in conjunction with PLSR modeling. An important result from this study was that a single model could be developed to accurately estimate the variation in leaf traits, including nitrogen and carbon content, lignin, fiber and cellulose, isotopic nitrogen-15, and leaf mass per area, across species, growth environments, throughout the vertical profile of a canopy, and with leaf lifespan. A residual analysis of the model prediction errors showed no significant biases observed by tree species, canopy position, or leaf age. Fresh-leaf reflectance spectroscopy was used to identify the linkages between leaf photosynthetic metabolism and leaf optical properties within controlled and natural environments, and across diverse plant species. Two key parameters controlling photosynthetic rates - the maximum rates of RuBisCO carboxylation (Vcmax) and RuBP regeneration ( Jmax) --- were directly estimated using leaf spectra and concurrent gas-exchange measurements. The models for each variable captured the pronounced temperature sensitivity of plants, and integrated the significant variability in metabolism across species

  3. A comparison of nutrient density scores for 100% fruit juices.

    PubMed

    Rampersaud, G C

    2007-05-01

    The 2005 Dietary Guidelines for Americans recommend that consumers choose a variety of nutrient-dense foods. Nutrient density is usually defined as the quantity of nutrients per calorie. Food and nutrition professionals should be aware of the concept of nutrient density, how it might be quantified, and its potential application in food labeling and dietary guidance. This article presents the concept of a nutrient density score and compares nutrient density scores for various 100% fruit juices. One hundred percent fruit juices are popular beverages in the United States, and although they can provide concentrated sources of a variety of nutrients, they can differ considerably in their nutrient profiles. Six methodologies were used to quantify nutrient density and 7 100% fruit juices were included in the analysis: apple, grape, pink grapefruit, white grapefruit, orange, pineapple, and prune. Food composition data were obtained from the USDA National Nutrient Database for Standard Reference, Release 18. Application of the methods resulted in nutrient density scores with a range of values and magnitudes. The relative scores indicated that citrus juices, particularly pink grapefruit and orange juice, were more nutrient dense compared to the other nonfortified 100% juices included in the analysis. Although the methods differed, the relative ranking of the juices based on nutrient density score was similar for each method. Issues to be addressed regarding the development and application of a nutrient density score include those related to food fortification, nutrient bioavailability, and consumer education and behavior.

  4. Correlations between leaf toughness and phenolics among species in contrasting environments of Australia and New Caledonia

    PubMed Central

    Read, Jennifer; Sanson, Gordon D.; Caldwell, Elizabeth; Clissold, Fiona J.; Chatain, Alex; Peeters, Paula; Lamont, Byron B.; De Garine-Wichatitsky, Michel; Jaffré, Tanguy; Kerr, Stuart

    2009-01-01

    Background and Aims Plants are likely to invest in multiple defences, given the variety of sources of biotic and abiotic damage to which they are exposed. However, little is known about syndromes of defence across plant species and how these differ in contrasting environments. Here an investigation is made into the association between carbon-based chemical and mechanical defences, predicting that species that invest heavily in mechanical defence of leaves will invest less in chemical defence. Methods A combination of published and unpublished data is used to test whether species with tougher leaves have lower concentrations of phenolics, using 125 species from four regions of Australia and the Pacific island of New Caledonia, in evergreen vegetation ranging from temperate shrubland and woodland to tropical shrubland and rainforest. Foliar toughness was measured as work-to-shear and specific work-to-shear (work-to-shear per unit leaf thickness). Phenolics were measured as ‘total phenolics’ and by protein precipitation (an estimate of tannin activity) per leaf dry mass. Key Results Contrary to prediction, phenolic concentrations were not negatively correlated with either measure of leaf toughness when examined across all species, within regions or within any plant community. Instead, measures of toughness (particularly work-to-shear) and phenolics were often positively correlated in shrubland and rainforest (but not dry forest) in New Caledonia, with a similar trend suggested for shrubland in south-western Australia. The common feature of these sites was low concentrations of soil nutrients, with evidence of P limitation. Conclusions Positive correlations between toughness and phenolics in vegetation on infertile soils suggest that additive investment in carbon-based mechanical and chemical defences is advantageous and cost-effective in these nutrient-deficient environments where carbohydrate may be in surplus. PMID:19098067

  5. The Genome Sequence of the Leaf-Cutter Ant Atta cephalotes Reveals Insights into Its Obligate Symbiotic Lifestyle

    PubMed Central

    Suen, Garret; Holt, Carson; Abouheif, Ehab; Bornberg-Bauer, Erich; Bouffard, Pascal; Caldera, Eric J.; Cash, Elizabeth; Cavanaugh, Amy; Denas, Olgert; Elhaik, Eran; Favé, Marie-Julie; Gadau, Jürgen; Gibson, Joshua D.; Graur, Dan; Grubbs, Kirk J.; Hagen, Darren E.; Harkins, Timothy T.; Helmkampf, Martin; Hu, Hao; Johnson, Brian R.; Kim, Jay; Marsh, Sarah E.; Moeller, Joseph A.; Muñoz-Torres, Mónica C.; Murphy, Marguerite C.; Naughton, Meredith C.; Nigam, Surabhi; Overson, Rick; Rajakumar, Rajendhran; Reese, Justin T.; Scott, Jarrod J.; Smith, Chris R.; Tao, Shu; Tsutsui, Neil D.; Viljakainen, Lumi; Wissler, Lothar; Yandell, Mark D.; Zimmer, Fabian; Taylor, James; Slater, Steven C.; Clifton, Sandra W.; Warren, Wesley C.; Elsik, Christine G.; Smith, Christopher D.; Weinstock, George M.; Gerardo, Nicole M.; Currie, Cameron R.

    2011-01-01

    Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colony's primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies. Mature leaf-cutter ant colonies contain millions of workers ranging in size from small garden tenders to large soldiers, resulting in one of the most complex polymorphic caste systems within ants. To begin uncovering the genomic underpinnings of this system, we sequenced the genome of Atta cephalotes using 454 pyrosequencing. One prediction from this ant's lifestyle is that it has undergone genetic modifications that reflect its obligate dependence on the fungus for nutrients. Analysis of this genome sequence is consistent with this hypothesis, as we find evidence for reductions in genes related to nutrient acquisition. These include extensive reductions in serine proteases (which are likely unnecessary because proteolysis is not a primary mechanism used to process nutrients obtained from the fungus), a loss of genes involved in arginine biosynthesis (suggesting that this amino acid is obtained from the fungus), and the absence of a hexamerin (which sequesters amino acids during larval development in other insects). Following recent reports of genome sequences from other insects that engage in symbioses with beneficial microbes, the A. cephalotes genome provides new insights into the symbiotic lifestyle of this ant and advances our understanding of host–microbe symbioses. PMID:21347285

  6. Leaf herbivory and decomposability in a Malaysian tropical rain forest.

    PubMed

    Kurokawa, Hiroko; Nakashizuka, Tohru

    2008-09-01

    There is accumulating evidence that similar suites of plant traits may affect leaf palatability and leaf litter decomposability. However, the possible association between leaf herbivory and litter decomposition rates across species in species-diverse natural ecosystems such as tropical rain forests remains unexplored, despite its importance in estimating the herbivory effects on carbon and nutrient cycling of ecosystems. We found no strong association between leaf herbivory and litter decomposition rates across 40 tree species in a Malaysian tropical rain forest, even though the leaf and litter traits were tightly correlated. This is because the leaf and litter traits related to herbivory and decomposition rates in the field were inconsistent. Leaf toughness accounted for only a small part of the variation in the herbivory rate, whereas a number of litter traits (the leaf mass per area, lignin to nitrogen ratio, and condensed tannin concentration) accurately predicted the decomposition rate across species. These results suggest that herbivory rate across species may not be strongly related to single leaf traits, probably because plant-herbivore interactions in tropical rain forests are highly diverse; on the other hand, plant-decomposer interactions are less specific and can be governed by litter chemicals. We also investigated two factors, phylogeny and tree functional types, that could affect the relationship between herbivory and decomposition across species. Phylogenetic relatedness among the species did not affect the relationship between herbivory and decomposition. In contrast, when the plants were segregated according to their leaf emergence pattern, we found a significant positive relationship between herbivory and decomposition rates for continuous-leafing species. In these species, the condensed tannin to N ratios in leaves and litter were related to herbivory and decomposition rates, respectively. However, we did not observe a similar trend for

  7. Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion

    DOE PAGESBeta

    Dong, Dr. Xuejun; Patton, J.; Gu, Lianhong; Wang, J.; Patton, B.

    2014-11-26

    The widespread invasion of exotic cool-season grasses in mixed-grass rangeland is diminishing the hope of bringing back the natural native plant communities. However, ecophysiological mechanisms explaining the relative competitiveness of these invasive grasses over the native species generally are lacking. In this study, we used experimental data collected in south-central North Dakota, USA to address this issue. Photosynthetic potential was obtained from the net assimilation (A) vs. internal CO2 (Ci) response curves from plants grown in a greenhouse. Plant success was defined as the average frequency measured over 25 years (1988 to 2012) on overflow range sites across five levelsmore » of grazing intensity. In addition, estimated leaf area index of individual species under field conditions was used to indicate plant success. The correlation between photosynthetic potential based on A/Ci curves and plant frequency was negative. The correlation between leaf photosynthesis and plant success (defined as leaf area within a unit land area) was also negative, although statistically weak. These results suggest that the two cool-season grasses, Poa pratensis and Bromus inermis, do not rely on superior leaf-level photosynthesis for competitive success. Instead, some other traits, such as early and late-season growth, may be more important for them to gain dominance in the mixed-grass prairie. We propose that the negative photosynthesis-frequency relation as observed in this study results from a strong competition for limited soil nutrients in the mixed-grass prairie. In conclusion, it has implications for the stability and productivity of the grassland under various human disruptions influencing the soil nutrient status.« less

  8. Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion

    SciTech Connect

    Dong, Dr. Xuejun; Patton, J.; Gu, Lianhong; Wang, J.; Patton, B.

    2014-11-26

    The widespread invasion of exotic cool-season grasses in mixed-grass rangeland is diminishing the hope of bringing back the natural native plant communities. However, ecophysiological mechanisms explaining the relative competitiveness of these invasive grasses over the native species generally are lacking. In this study, we used experimental data collected in south-central North Dakota, USA to address this issue. Photosynthetic potential was obtained from the net assimilation (A) vs. internal CO2 (Ci) response curves from plants grown in a greenhouse. Plant success was defined as the average frequency measured over 25 years (1988 to 2012) on overflow range sites across five levels of grazing intensity. In addition, estimated leaf area index of individual species under field conditions was used to indicate plant success. The correlation between photosynthetic potential based on A/Ci curves and plant frequency was negative. The correlation between leaf photosynthesis and plant success (defined as leaf area within a unit land area) was also negative, although statistically weak. These results suggest that the two cool-season grasses, Poa pratensis and Bromus inermis, do not rely on superior leaf-level photosynthesis for competitive success. Instead, some other traits, such as early and late-season growth, may be more important for them to gain dominance in the mixed-grass prairie. We propose that the negative photosynthesis-frequency relation as observed in this study results from a strong competition for limited soil nutrients in the mixed-grass prairie. In conclusion, it has implications for the stability and productivity of the grassland under various human disruptions influencing the soil nutrient status.

  9. C:N:P stoichiometry and leaf traits of halophytes in an arid saline environment, northwest China.

    PubMed

    Wang, Lilong; Zhao, Guanxiang; Li, Meng; Zhang, Mingting; Zhang, Lifang; Zhang, Xinfang; An, Lizhe; Xu, Shijian

    2015-01-01

    Salinization is an important and increasingly prevalent issue which has broad and profound effects on plant survival and distribution pattern. To understand the patterns and potential drivers of leaf traits in saline environments, we determined the soil properties, leaf morphological traits (specific leaf area, SLA, and leaf dry matter content, LDMC), leaf chemical traits (leaf carbon, C, nitrogen, N, and phosphorus, P, stoichiometry) based on 142 observations collected from 23 sites in an arid saline environment, which is a vulnerable ecosystem in northwest China. We also explored the relationships among leaf traits, the responses of leaf traits, and plant functional groups (herb, woody, and succulent woody) to various saline environments. The arid desert halophytes were characterized by lower leaf C and SLA levels, higher N, but stable P and N:P. The leaf morphological traits were correlated significantly with the C, N, and P contents across all observations, but they differed within each functional group. Succulent woody plants had the lowest leaf C and highest leaf N levels among the three functional groups. The growth of halophytes might be more limited by N rather than P in the study area. GLM analysis demonstrated that the soil available nutrients and plant functional groups, but not salinity, were potential drivers of leaf C:N:P stoichiometry in halophytes, whereas species differences accounted for the largest contributions to leaf morphological variations. Our study provides baseline information to facilitate the management and restoration of arid saline desert ecosystem.

  10. C:N:P Stoichiometry and Leaf Traits of Halophytes in an Arid Saline Environment, Northwest China

    PubMed Central

    Wang, Lilong; Zhao, Guanxiang; Li, Meng; Zhang, Mingting; Zhang, Lifang; Zhang, Xinfang; An, Lizhe; Xu, Shijian

    2015-01-01

    Salinization is an important and increasingly prevalent issue which has broad and profound effects on plant survival and distribution pattern. To understand the patterns and potential drivers of leaf traits in saline environments, we determined the soil properties, leaf morphological traits (specific leaf area, SLA, and leaf dry matter content, LDMC), leaf chemical traits (leaf carbon, C, nitrogen, N, and phosphorus, P, stoichiometry) based on 142 observations collected from 23 sites in an arid saline environment, which is a vulnerable ecosystem in northwest China. We also explored the relationships among leaf traits, the responses of leaf traits, and plant functional groups (herb, woody, and succulent woody) to various saline environments. The arid desert halophytes were characterized by lower leaf C and SLA levels, higher N, but stable P and N:P. The leaf morphological traits were correlated significantly with the C, N, and P contents across all observations, but they differed within each functional group. Succulent woody plants had the lowest leaf C and highest leaf N levels among the three functional groups. The growth of halophytes might be more limited by N rather than P in the study area. GLM analysis demonstrated that the soil available nutrients and plant functional groups, but not salinity, were potential drivers of leaf C:N:P stoichiometry in halophytes, whereas species differences accounted for the largest contributions to leaf morphological variations. Our study provides baseline information to facilitate the management and restoration of arid saline desert ecosystem. PMID:25798853

  11. The plant ionome revisited by the nutrient balance concept.

    PubMed

    Parent, Serge-Étienne; Parent, Léon Etienne; Egozcue, Juan José; Rozane, Danilo-Eduardo; Hernandes, Amanda; Lapointe, Line; Hébert-Gentile, Valérie; Naess, Kristine; Marchand, Sébastien; Lafond, Jean; Mattos, Dirceu; Barlow, Philip; Natale, William

    2013-01-01

    Tissue analysis is commonly used in ecology and agronomy to portray plant nutrient signatures. Nutrient concentration data, or ionomes, belongs to the compositional data class, i.e., multivariate data that are proportions of some whole, hence carrying important numerical properties. Statistics computed across raw or ordinary log-transformed nutrient data are intrinsically biased, hence possibly leading to wrong inferences. Our objective was to present a sound and robust approach based on a novel nutrient balance concept to classify plant ionomes. We analyzed leaf N, P, K, Ca, and Mg of two wild and six domesticated fruit species from Canada, Brazil, and New Zealand sampled during reproductive stages. Nutrient concentrations were (1) analyzed without transformation, (2) ordinary log-transformed as commonly but incorrectly applied in practice, (3) additive log-ratio (alr) transformed as surrogate to stoichiometric rules, and (4) converted to isometric log-ratios (ilr) arranged as sound nutrient balance variables. Raw concentration and ordinary log transformation both led to biased multivariate analysis due to redundancy between interacting nutrients. The alr- and ilr-transformed data provided unbiased discriminant analyses of plant ionomes, where wild and domesticated species formed distinct groups and the ionomes of species and cultivars were differentiated without numerical bias. The ilr nutrient balance concept is preferable to alr, because the ilr technique projects the most important interactions between nutrients into a convenient Euclidean space. This novel numerical approach allows rectifying historical biases and supervising phenotypic plasticity in plant nutrition studies.

  12. Simulated browsing affects leaf shedding phenology and litter quality of oak and birch saplings.

    PubMed

    Palacio, S; Hester, A J; Maestro, M; Millard, P

    2013-04-01

    Herbivore effects on leaf litter can have a strong impact on ecosystem nutrient cycling. Although such effects are well described for insect herbivory, research on the impacts of browsing by mammalian herbivores on leaf litter dynamics and nutrient cycling has been more limited, particularly at the level of the individual plant. Clipping treatments (66% shoot removal twice, plus unclipped) were applied to analyse the effect of browsing on the phenology (start date and pattern of leaf shedding) and leaf litter quality (nitrogen (N), soluble sugars, starch and total non-structural carbohydrate concentrations, plus C : N ratios) of Betula pubescens Ehrh. and Quercus petraea [Matt.] Liebl. saplings. Clipping decreased leaf litter biomass and delayed leaf senescence and shedding, but did not change the phenological timing of litterfall between senescence and shedding. The quality of leaf litter of both species was increased by simulated browsing, through an increase in N and carbohydrate concentrations (mainly soluble sugars) and a decreased C : N ratio. This is the first evidence we are aware of that browsing may cause changes in leaf shedding phenology, delaying the process without altering its pattern. Our results also indicate that simulated browsing increases the quality of leaf litter. However, the potential positive effect of browsing on N cycling through litter quality may be offset by its negative impact on the amount of N shed per tree.

  13. Relationship of soybean aphid (Hemiptera: Aphididae) to soybean plant nutrients, landscape structure, and natural enemies.

    PubMed

    Noma, Takuji; Gratton, Claudio; Colunga-Garcia, Manuel; Brewer, Michael J; Mueller, Emily E; Wyckhuys, Kris A G; Heimpel, George E; O'Neal, Matthew E

    2010-02-01

    In the north central United States, populations of the exotic soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), are highly variable across space, complicating effective aphid management. In this study we examined relationships of plant nutrients, landscape structure, and natural enemies with soybean aphid abundance across Iowa, Michigan, Minnesota, and Wisconsin, representing the range of conditions where soybean aphid outbreaks have occurred since its introduction. We sampled soybean aphid and its natural enemies, quantified vegetation land cover and measured soybean nutrients (potassium [K] and nitrogen [N]) in 26 soybean sites in 2005 and 2006. Multiple regression models found that aphid abundance was negatively associated with leaf K content in 2005, whereas it was negatively associated with habitat diversity (Simpson's index) and positively associated with leaf N content in 2006. These variables accounted for 25 and 27% of aphid variability in 2005 and 2006, respectively, suggesting that other sources of variability are also important. In addition, K content of soybean plants decreased with increasing prevalence of corn-soybean cropland in 2005, suggesting that landscapes that have a high intensification of agriculture (as indexed by increasing corn and soybean) are more likely to have higher aphid numbers. Soybean aphid natural enemies, 26 species of predators and parasitoids, was positively related to aphid abundance; however, enemy-to-aphid abundance ratios were inversely related to aphid density, suggesting that soybean aphids are able to escape control by resident natural enemies. Overall, soybean aphid abundance was most associated with soybean leaf chemistry and landscape heterogeneity. Agronomic options that can ameliorate K deficiency and maintaining heterogeneity in the landscape may reduce aphid risk.

  14. Ecological role of reindeer summer browsing in the mountain birch (Betula pubescens ssp. czerepanovii) forests: effects on plant defense, litter decomposition, and soil nutrient cycling.

    PubMed

    Stark, Sari; Julkunen-Tiitto, Riitta; Kumpula, Jouko

    2007-03-01

    Mammalian herbivores commonly alter the concentrations of secondary compounds in plants and, by this mechanism, have indirect effects on litter decomposition and soil carbon and nutrient cycling. In northernmost Fennoscandia, the subarctic mountain birch (Betula pubescens ssp. czerepanovii) forests are important pasture for the semidomestic reindeer (Rangifer tarandus). In the summer ranges, mountain birches are intensively browsed, whereas in the winter ranges, reindeer feed on ground lichens, and the mountain birches remain intact. We analyzed the effect of summer browsing on the concentrations of secondary substances, litter decomposition, and soil nutrient pools in areas that had been separated as summer or winter ranges for at least 20 years, and we predicted that summer browsing may reduce levels of secondary compounds in the mountain birch and, by this mechanism, have an indirect effect on the decomposition of mountain birch leaf litter and soil nutrient cycling. The effect of browsing on the concentration of secondary substances in the mountain birch leaves varied between different years and management districts, but in some cases, the concentration of condensed tannins was lower in the summer than in the winter ranges. In a reciprocal litter decomposition trial, both litter origin and emplacement significantly affected the litter decomposition rate. Decomposition rates were faster for the litter originating from and placed into the summer range. Soil inorganic nitrogen (N) concentrations were higher in the summer than in the winter ranges, which indicates that reindeer summer browsing may enhance the soil nutrient cycling. There was a tight inverse relationship between soil N and foliar tannin concentrations in the winter range but not in the summer range. This suggests that in these strongly nutrient-limited ecosystems, soil N availability regulates the patterns of resource allocation to condensed tannins in the absence but not in the presence of browsing.

  15. Deer predation on leaf miners via leaf abscission

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

    The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer ( Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

  16. Physiological strategies of co-occurring oaks in a water- and nutrient-limited ecosystem.

    PubMed

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

    2014-02-01

    Oak species are well suited to water-limited conditions by either avoiding water stress through deep rooting or tolerating water stress through tight stomatal control. In co-occurring species where resources are limited, species may either partition resources in space and/or time or exhibit differing efficiencies in the use of limited resources. Therefore, this study seeks to determine whether two co-occurring oak species (Quercus prinus L. and Quercus velutina Lam.) differ in physiological parameters including photosynthesis, stomatal conductance, water-use (WUE) and nitrogen-use efficiency (NUE), as well as to characterize transpiration and average canopy stomatal responses to climatic variables in a sandy, well-drained and nutrient-limited ecosystem. The study was conducted in the New Jersey Pinelands and we measured sap flux over a 3-year period, as well as leaf gas exchange, leaf nitrogen and carbon isotope concentrations. Both oak species showed relatively steep increases in leaf-specific transpiration at low vapor pressure deficit (VPD) values before maximum transpiration rates were achieved, which were sustained over a broad range in VPD. This suggests tight stomatal control over transpiration in both species, although Q. velutina showed significantly higher leaf-level and canopy-level stomatal conductance than Q. prinus. Average daytime stomatal conductance was positively correlated with soil moisture and both oak species maintained at least 75% of their maximum canopy stomatal conductance at soil moistures in the upper soil layer (0-0.3 m) as low as 0.03 m(3) m(3)(-3). Quercus velutina had significantly higher photosynthetic rates, maximum Rubisco-limited and electron-transport-limited carboxylation rates, dark respiration rates and nitrogen concentration per unit leaf area than Q. prinus. However, both species exhibited similar WUEs and NUEs. Therefore, Q. prinus has a more conservative resource-use strategy, while Q. velutina may need to exploit niches

  17. Duodenal luminal nutrient sensing

    PubMed Central

    Rønnestad, Ivar; Akiba, Yasutada; Kaji, Izumi; Kaunitz, Jonathan D

    2016-01-01

    The gastrointestinal mucosa is exposed to numerous chemical substances and microorganisms, including macronutrients, micronutrients, bacteria, endogenous ions, and proteins. The regulation of mucosal protection, digestion, absorption and motility is signaled in part by luminal solutes. Therefore, luminal chemosensing is an important mechanism enabling the mucosa to monitor luminal conditions, such as pH, ion concentrations, nutrient quantity, and microflora. The duodenal mucosa shares luminal nutrient receptors with lingual taste receptors in order to detect the five basic tastes, in addition to essential nutrients, and unwanted chemicals. The recent ‘de-orphanization’ of nutrient sensing G protein-coupled receptors provides an essential component of the mechanism by which the mucosa senses luminal nutrients. In this review, we will update the mechanisms of and underlying physiological and pathological roles in luminal nutrient sensing, with a main focus on the duodenal mucosa. PMID:25113991

  18. Remote sensing of leaf N to improve carbon assimilation prediction

    NASA Astrophysics Data System (ADS)

    Loozen, Yasmina; Rebel, Karin; Karssenberg, Derek; de Jong, Steven; Wassen, Martin

    2016-04-01

    Predicting and understanding carbon assimilation by terrestrial vegetation remains fundamental in the context of climate change. Carbon and nitrogen cycles are linked as nitrogen is an essential nutrient for plant growth. In this respect the N cycle is integrated into vegetation models predicting vegetation carbon uptake. However plant traits within the N cycle, such as leaf nitrogen, are lacking at large scales, which complicates the calibration and optimization of the N cycling modelling modules. Remote sensing techniques could offer the possibility to detect leaf N concentration at continental scales. In fact, it has already been used to sense leaf N at local, e.g. in agricultural oriented applications, as well as at regional scales. The objective of this study is to enhance the availability of leaf N estimates in forested ecosystems at European scale using remote sensing products. European forest leaf N data were obtained from the TRY database. The MERIS Terrestrial chlorophyll Index (MTCI) Level 3 product as well as two reflectance bands in the NIR region (band centers at 865 and 885nm) both from MERIS aboard ENVISAT (ESA) were used to study statistical relationship with leaf N data. In a first step, we analyzed 1892 Catalonian (NE Spain) forest plots using a linear regression method. The regressions results between leaf N and either MTCI or NIR bands were significant (p< 0.001). The R-square for the regression between leaf N and MTCI was equal to 0.13. The method performed better for broadleaves deciduous plots (R-square = 0.11) than for needleleaves or broadleaves evergreen plots. The relationship between leaf N and MTCI was also higher for the plots sampled during summer (R-square = 0.28 in July) than for the plots sampled during the rest of the year. In a second step the method will be applied on and will include more diverse forest types at the European level.

  19. Biology and host range of Tecmessa elegans (Lepidoptera: Notodontidae), a leaf-feeding moth evaluated as a potential biological control agent for Schinus terebinthifolius (Sapindales: Anacardiaceae) in the United States.

    PubMed

    Oleiro, Marina; Mc Kay, Fernando; Wheeler, Gregory S

    2011-06-01

    During surveys for natural enemies that could be used as classical biological control agents of Schinus terebinthifolius Raddi (Brazilian pepper), the caterpillar, Tecmessa elegans Schaus (Lepidoptera: Notodontidae), was recorded feeding on the leaves of the shrub in South America. The biology and larval and adult host range of this species were examined to determine the insect's suitability for biological control of this invasive weed in North America and Hawaii. Biological observations indicate that the larvae have five instars. When disturbed, the late instar larvae emit formic acid from a prothoracic gland that may protect larvae from generalist predators. Larval host range tests conducted both in South and North America indicated that this species feeds and completes development primarily on members of the Anacardiaceae within the tribe Rhoeae. Oviposition tests indicated that when given a choice in large cages the adults will select the target weed over Pistacia spp. However, considering the many valued plant species in its host range, especially several North American natives, this species will not be considered further for biological control of S. terebinthifolius in North America.

  20. Posidonia oceanica meadow: a low nutrient high chlorophyll (LNHC) system?

    PubMed Central

    Gobert, Sylvie; Laumont, Noémie; Bouquegneau, Jean-Marie

    2002-01-01

    Background In spite of very low nutrient concentrations in its vicinity – both column and pore waters-, the Posidonia oceanica of the Revellata Bay displays high biomass and productivity. We measured the nutrient fluxes from the sediment into the water enclosed among the leaf shoots ("canopy water") to determine if it is possible source of nutrients for P. oceanica leaves. Results During the summer, the canopy water appears to act as a nutrient reservoir for the plant. During that period, the canopy water layer displays both a temperature 0.5°C cooler than the upper water column, and a much higher nutrient content, as shown in this work using a very simple original technique permitting to sample water with a minimal disturbance of the water column's vertical structure. Despite low nutrient concentrations in pore water, mean net fluxes were measured from the sediment to the canopy water. These fluxes are sufficient to provide 20% of the mean daily nitrogen and phosphorus requirement of the P. oceanica shoots. Conclusion An internal cycling of nutrients from P. oceanica senescent leaves was previously noted as an efficient strategy to help face low nutrient availability. The present study points out a second strategy which consists in holding back, in the canopy, the nutrients released at the water-sediment interface. This process occurs when long leaves, during poor nutrient periods in the water column, providing, to P. oceanica, the possibility to develop, high biomass, high chlorophyll quantities in low nutrient environment (a Low Nutrients High Chlorophyll system). PMID:12188926

  1. Wind-induced leaf transpiration

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Wei; Chu, Chia-Ren; Hsieh, Cheng-I.; Palmroth, Sari; Katul, Gabriel G.

    2015-12-01

    While the significance of leaf transpiration (fe) on carbon and water cycling is rarely disputed, conflicting evidence has been reported on how increasing mean wind speed (U) impacts fe from leaves. Here, conditions promoting enhancement or suppression of fe with increasing U for a wide range of environmental conditions are explored numerically using leaf-level gas exchange theories that combine a stomatal conductance model based on optimal water use strategies (maximizing the 'net' carbon gain at a given fe), energy balance considerations, and biochemical demand for CO2. The analysis showed monotonic increases in fe with increasing U at low light levels. However, a decline in modeled fe with increasing U were predicted at high light levels but only in certain instances. The dominant mechanism explaining this decline in modeled fe with increasing U is a shift from evaporative cooling to surface heating at high light levels. New and published sap flow measurements for potted Pachira macrocarpa and Messerschmidia argentea plants conducted in a wind tunnel across a wide range of U (2 - 8 m s-1) and two different soil moisture conditions were also employed to assess how fe varies with increasing U. The radiative forcing imposed in the wind tunnel was only restricted to the lower end of expected field conditions. At this low light regime, the findings from the wind tunnel experiments were consistent with the predicted trends.

  2. [Influence of photosynthetic parameters on leaf longevity].

    PubMed

    Vasfilov, S P

    2015-01-01

    Higher plants show a wide range of leaf lifespan (LL) variability. LL is calculated as a sum of functional LL(f) (corresponding to the time of active photosynthesis and CO2 accumulation in the leaf) and nonfunctional LL(n) (the time of photosynthetic activity absence). For evergreen species of boreal zones, LL(n) corresponds to the period of winter rest. Photosynthetic potential of leaf (PPL), interpreted as the maximum possible amount of CO2 that can be fixed during its life, can be estimated on the basis of maximum photosynthesis rate (P(a)) dynamics during LL(f); the maximum (P(a max)) being achieved in mature leaf. Photosynthetic potential depends on LL(f) more strongly than on P(a max). The PPL/LL(f) ratio is indicative of the rate of PPL realization over leaf lifespan. As LL(f) shows strong positive correlation with LL, the latter parameter can also characterize the rate of PPL realization. Long LL(f) in evergreen species provides higher PPL, which is advantageous by comparison with deciduous ones. In evergreen species, the PPL itself is realized slower than in deciduous ones. The increase in LL(f) and LL is accompanied by the increase in leaf constructional cost (LCC(a)) as well as the decrease in photosynthesis rate. At that, photosynthesis rate per unit of dry weight (P(m)) decreases much faster than that per unit of leaf area (P(a)). Apparently, when considering dry leaf weight, the apoplast share seems to be much higher in long-living leaves of evergreen species than in short-living leaves of deciduous species. The leaf payback (LP) may be stabilized by unidirectional shifts in PPL and LCC(a). Species with short/long LL(f) and high/low PPL realization rate are typical for early/late succession stages and for habitats with the environmental conditions favorable/adverse for photosynthesis and growth. If the conditions for photosynthesis and growth are favorable, high PPL realization rate provides advantage in competition. The PPL realization rate is

  3. Seasonality and phenology alter functional leaf traits.

    PubMed

    McKown, Athena D; Guy, Robert D; Azam, M Shofiul; Drewes, Eric C; Quamme, Linda K

    2013-07-01

    In plant ecophysiology, functional leaf traits are generally not assessed in relation to phenological phase of the canopy. Leaf traits measured in deciduous perennial species are known to vary between spring and summer seasons, but there is a knowledge gap relating to the late-summer phase marked by growth cessation and bud set occurring well before fall leaf senescence. The effects of phenology on canopy physiology were tested using a common garden of over 2,000 black cottonwood (Populus trichocarpa) individuals originating from a wide geographical range (44-60ºN). Annual phenological events and 12 leaf-based functional trait measurements were collected spanning the entire summer season prior to, and following, bud set. Patterns of seasonal trait change emerged by synchronizing trees using their date of bud set. In particular, photosynthetic, mass, and N-based traits increased substantially following bud set. Most traits were significantly different between pre-bud set and post-bud set phase trees, with many traits showing at least 25% alteration in mean value. Post-bud set, both the significance and direction of trait-trait relationships could be modified, with many relating directly to changes in leaf mass. In Populus, these dynamics in leaf traits throughout the summer season reflected a shift in whole plant physiology, but occurred long before the onset of leaf senescence. The marked shifts in measured trait values following bud set underscores the necessity to include phenology in trait-based ecological studies or large-scale phenotyping efforts, both at the local level and larger geographical scale.

  4. Response of plant nutrient stoichiometry to fertilization varied with plant tissues in a tropical forest

    PubMed Central

    Mo, Qifeng; Zou, Bi; Li, Yingwen; Chen, Yao; Zhang, Weixin; Mao, Rong; Ding, Yongzhen; Wang, Jun; Lu, Xiankai; Li, Xiaobo; Tang, Jianwu; Li, Zhian; Wang, Faming

    2015-01-01

    Plant N:P ratios are widely used as indices of nutrient limitation in terrestrial ecosystems, but the response of these metrics in different plant tissues to altered N and P availability and their interactions remains largely unclear. We evaluated changes in N and P concentrations, N:P ratios of new leaves (<1 yr), older leaves (>1 yr), stems and mixed fine roots of seven species after 3-years of an N and P addition experiment in a tropical forest. Nitrogen addition only increased fine root N concentrations. P addition increased P concentrations among all tissues. The N × P interaction reduced leaf and stem P concentrations, suggesting a negative effect of N addition on P concentrations under P addition. The reliability of using nutrient ratios as indices of soil nutrient availability varied with tissues: the stoichiometric metrics of stems and older leaves were more responsive indicators of changed soil nutrient availability than those of new leaves and fine roots. However, leaf N:P ratios can be a useful indicator of inter-specific variation in plant response to nutrients availability. This study suggests that older leaf is a better choice than other tissues in the assessment of soil nutrient status and predicting plant response to altered nutrients using nutrients ratios. PMID:26416169

  5. Response of plant nutrient stoichiometry to fertilization varied with plant tissues in a tropical forest.

    PubMed

    Mo, Qifeng; Zou, Bi; Li, Yingwen; Chen, Yao; Zhang, Weixin; Mao, Rong; Ding, Yongzhen; Wang, Jun; Lu, Xiankai; Li, Xiaobo; Tang, Jianwu; Li, Zhian; Wang, Faming

    2015-09-29

    Plant N:P ratios are widely used as indices of nutrient limitation in terrestrial ecosystems, but the response of these metrics in different plant tissues to altered N and P availability and their interactions remains largely unclear. We evaluated changes in N and P concentrations, N:P ratios of new leaves (<1 yr), older leaves (>1 yr), stems and mixed fine roots of seven species after 3-years of an N and P addition experiment in a tropical forest. Nitrogen addition only increased fine root N concentrations. P addition increased P concentrations among all tissues. The N × P interaction reduced leaf and stem P concentrations, suggesting a negative effect of N addition on P concentrations under P addition. The reliability of using nutrient ratios as indices of soil nutrient availability varied with tissues: the stoichiometric metrics of stems and older leaves were more responsive indicators of changed soil nutrient availability than those of new leaves and fine roots. However, leaf N:P ratios can be a useful indicator of inter-specific variation in plant response to nutrients availability. This study suggests that older leaf is a better choice than other tissues in the assessment of soil nutrient status and predicting plant response to altered nutrients using nutrients ratios.

  6. Nutrient limitation and morphological plasticity of the carnivorous pitcher plant Sarracenia purpurea in contrasting wetland environments.

    PubMed

    Bott, Terry; Meyer, Gretchen A; Young, Erica B

    2008-01-01

    * Plasticity of leaf nutrient content and morphology, and macronutrient limitation were examined in the northern pitcher plant, Sarracenia purpurea subsp. purpurea, in relation to soil nutrient availability in an open, neutral pH fen and a shady, acidic ombrotrophic bog, over 2 yr following reciprocal transplantation of S. purpurea between the wetlands. * In both wetlands, plants were limited by nitrogen (N) but not phosphorus (P) (N content < 2% DW(-1), N : P < 14) but photosynthetic quantum yields were high (F(V)/F(M) > 0.79). Despite carnivory, leaf N content correlated with dissolved N availability to plant roots (leaf N vs , r(2) = 0.344, P < 0.0001); carnivorous N acquisition did not apparently overcome N limitation. * Following transplantation, N content and leaf morphological traits changed in new leaves to become more similar to plants in the new environment, reflecting wetland nutrient availability. Changes in leaf morphology were faster when plants were transplanted from fen to bog than from bog to fen, possibly reflecting a more stressful environment in the bog. * Morphological plasticity observed in response to changes in nutrient supply to the roots in natural habitats complements previous observations of morphological changes with experimental nutrient addition to pitchers.

  7. [Characteristics of leaf carbon, nitrogen and phosphorus stoichiometry in relation to plant size of Machilus pauhoi].

    PubMed

    Zhang, Lei-lei; Zhong, Quan-lin; Cheng, Dong-liang; Zhang, Zhong-rui; Fei, Ling; Xu, Chao-bin; He, Li-zhong; Wang, Wei-jun

    2015-07-01

    To explore the effects of stand age on variation patterns of leaf C, N, P stoichiometric characteristics of Machilus pauhoi, two stands, i.e., 9 and 13 years old, were selected. The relationships between leaf nutrient contents (C, N and P) and diameters at breast height (DBH) of individual plants were analyzed. The data revealed that the individual variations of seedlings in M. pauhoi stands were strengthened with the stand development. The stand age had significant effects on leaf C, N, P contents and C:N ratio but not on C:P and N: P ratios. Specifically, the mean values of leaf C, N, P contents and N:P ratio in the 9-year-old stand were lower than those in the 13-year-old stand, whereas, inverse pattern of C:N and C:P ratios were found in the two stands. Furthermore, leaf N and P stoichiometry varied significantly within the stand. Specifically, leaf N and P contents, as well as their stoichiometric ratios, linearly correlated with DBH in the 9-year-old stand. On the contrary, leaf N and P stoichiometry showed quadratic correlation in 13-year-old stand (except leaf C:N which linearly correlated with DBH). Lastly, nutrient transfer rates of leaf N and P in the 9-year-old stand were higher than that in 13-year-old stand, and the discrepancies of leaf nutrient transfer strategy between growing and non-growing seasons were caused by the different growth phases and environmental conditions. PMID:26720927

  8. [Characteristics of leaf carbon, nitrogen and phosphorus stoichiometry in relation to plant size of Machilus pauhoi].

    PubMed

    Zhang, Lei-lei; Zhong, Quan-lin; Cheng, Dong-liang; Zhang, Zhong-rui; Fei, Ling; Xu, Chao-bin; He, Li-zhong; Wang, Wei-jun

    2015-07-01

    To explore the effects of stand age on variation patterns of leaf C, N, P stoichiometric characteristics of Machilus pauhoi, two stands, i.e., 9 and 13 years old, were selected. The relationships between leaf nutrient contents (C, N and P) and diameters at breast height (DBH) of individual plants were analyzed. The data revealed that the individual variations of seedlings in M. pauhoi stands were strengthened with the stand development. The stand age had significant effects on leaf C, N, P contents and C:N ratio but not on C:P and N: P ratios. Specifically, the mean values of leaf C, N, P contents and N:P ratio in the 9-year-old stand were lower than those in the 13-year-old stand, whereas, inverse pattern of C:N and C:P ratios were found in the two stands. Furthermore, leaf N and P stoichiometry varied significantly within the stand. Specifically, leaf N and P contents, as well as their stoichiometric ratios, linearly correlated with DBH in the 9-year-old stand. On the contrary, leaf N and P stoichiometry showed quadratic correlation in 13-year-old stand (except leaf C:N which linearly correlated with DBH). Lastly, nutrient transfer rates of leaf N and P in the 9-year-old stand were higher than that in 13-year-old stand, and the discrepancies of leaf nutrient transfer strategy between growing and non-growing seasons were caused by the different growth phases and environmental conditions.

  9. Leaf area and net photosynthesis during development of Prunus serotina seedlings.

    PubMed

    Horsley, S B; Gottschalk, K W

    1993-01-01

    We used the plastochron index to study the relationship between plant age, leaf age and development, and net photosynthesis of black cherry (Prunus serotina Ehrh.) seedlings. Leaf area and net photosynthesis were measured on all leaves >/= 75 mm of plants ranging in age from 7 to 20 plastochrons. Effects of plant developmental stage on leaf area and net photosynthesis were evaluated for leaves of differing age (horizontal series), leaves on plants of constant age (vertical series), and leaves of constant age (oblique series). Regression techniques were used to estimate leaf area from leaf blade dimensions. The best equations for predicting leaf area had R(2) values of 0.991-0.992 and used linear or logarithmic functions of both leaf length and width. Suitable, but less precise, equations with R(2) values of 0.946-0.962 were developed from either leaf length or leaf width. Leaf area development in black cherry seedlings was similar to that in other indeterminate species. Leaves of young plants reached full expansion at a lower leaf plastochron age than leaves of older plants. Maximum net photosynthesis per unit leaf area occurred 2-3 plastochrons before full leaf expansion. There was strong ontogenetic drift in net photosynthesis with leaf age; net photosynthesis decreased as plant age increased in leaves of the same plastochron age. Plots of the oblique series were particularly useful in providing information about interaction effects. PMID:14969934

  10. Ozone alters the concentrations of nutrients in bean tissue

    SciTech Connect

    Tingey, D.T.; Rodecap, K.D.; Lee, E.H.; Moser, T.J.; Hogsett, W.E.

    1986-01-01

    Studies were conducted to determine the impact of ozone on the nutrient concentrations in tissue from various organs of beans (Phaseolus vulgaris L. cv Bush Bluelake 290). The plants were exposed to episodic concentrations of ozone in open-top field exposure chambers from soon after emergence until pod maturity. At harvest the leaf, stem, root and pod tissue were separated and dried (at 70C) to a constant weight. Nutrient concentrations in the tissue were determined using an inductively coupled plasma atomic emission spectrometer. Ozone exposure decreased the foliar concentrations of only four of the twelve nutrients analyzed (Ca, Mg, Fe and Mn) and increased the concentrations of three nutrients (K,P and Mo) in the pods. There were no significant changes in the macro- or micronutrient levels in the stem or root tissue. The decreased concentrations in the foliage appear to be the result of reduced transport into the leaves rather than reduced uptake or leaching.

  11. Detection of wine grape nutrient levels using visible and near infrared 1nm spectral resolution remote sensing

    NASA Astrophysics Data System (ADS)

    Anderson, Grant; van Aardt, Jan; Bajorski, Peter; Vanden Heuvel, Justine

    2016-05-01

    The grape industry relies on regular crop assessment to aid in the day-to-day and seasonal management of their crop. More specifically, there are six key nutrients of interest to viticulturists in the growing of wine grapes, namely nitrogen, potassium, phosphorous, magnesium, zinc and boron. Traditional methods of determining the levels of these nutrients are through collection and chemical analysis of petiole samples from the grape vines themselves. We collected ground-level observations of the spectra of the grape vines, using a hyperspectral spectrometer (0.4-2.5um), at the same time that petioles samples were harvested. We then interpolated the data into a consistent 1 nm spectral resolution before comparing it to the nutrient data collected. This nutrient data came from both the industry standard petiole analysis, as well as an additional leaf-level analysis. The data were collected for two different grape cultivars, both during bloom and veraison periods to provide variability, while also considering the impact of temporal/seasonal change. A narrow-band NDI (Normalized Difference Index) approach, as well as a simple ratio index, was used to determine the correlation of the reflectance data to the nutrient data. This analysis was limited to the silicon photodiode range to increase the utility of our approach for wavelength-specific cameras (via spectral filters) in a low cost drone platform. The NDI generated correlation coefficients were as high as 0.80 and 0.88 for bloom and veraison, respectively. The ratio index produced correlation coefficient results that are the same at two decimal places with 0.80 and 0.88. These results bode well for eventual non-destructive, accurate and precise assessment of vineyard nutrient status.

  12. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

    Maple Leaf Outdoor Centre (Ontario) has added year-round outdoor education facilities and programs to help support its summer camp for disadvantaged children. Schools, youth centers, religious groups, and athletic teams conduct their own programs, collaborate with staff, or use staff-developed programs emphasizing adventure education and personal…

  13. Bacterial leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot has been reported in Australia (Queensland), Egypt, El Salvador, India, Japan, Nicaragua, Sudan, and the United States (Florida, Iowa, Kansas, Maryland, and Wisconsin). It occasionally causes locally severe defoliation and post-emergence damping-off and stunting. The disease is...

  14. Comparative leaf development in angiosperms.

    PubMed

    Tsukaya, Hirokazu

    2014-02-01

    Recent accumulation of our knowledge on basic leaf development mechanisms in model angiosperm species has allowed us to pursue evolutionary development (evo/devo) studies of various kinds of leaf development. As a result, unexpected findings and clues have been unearthed aiding our understanding of the mechanisms involved in the diversity of leaf morphology, although the covered remain limited. In this review, we highlight recent findings of diversified leaf development in angiosperms.

  15. Physiological responses of the seagrass Thalassia hemprichii (Ehrenb.) Aschers as indicators of nutrient loading.

    PubMed

    Zhang, Jingping; Huang, Xiaoping; Jiang, Zhijian

    2014-06-30

    To select appropriate bioindicators for the evaluation of the influence of nutrients from human activities in a Thalassia hemprichii meadow, environmental variables and plant performance parameters were measured in Xincun Bay, Hainan Island, South China. Nutrient concentrations in the bay decreased along a gradient from west to southeast. Moreover, the nutrients decreased with an increase in the distance from the shore on the southern side of the bay. Among the candidate indicators, the P content of the tissues closely mirrored the two nutrient loading gradients. The epiphytic algae biomass and the N content in the tissues mirrored one of the two nutrient loading trends. The leaf length, however, exhibited a significant negative correlation with the nutrient gradients. We propose that changes in the P content of T. hemprichii, followed by epiphytic algae biomass and N content of the tissues, may be the useful indicators of nutrient loading to coastal ecosystems. PMID:24433998

  16. Physiological responses of the seagrass Thalassia hemprichii (Ehrenb.) Aschers as indicators of nutrient loading.

    PubMed

    Zhang, Jingping; Huang, Xiaoping; Jiang, Zhijian

    2014-06-30

    To select appropriate bioindicators for the evaluation of the influence of nutrients from human activities in a Thalassia hemprichii meadow, environmental variables and plant performance parameters were measured in Xincun Bay, Hainan Island, South China. Nutrient concentrations in the bay decreased along a gradient from west to southeast. Moreover, the nutrients decreased with an increase in the distance from the shore on the southern side of the bay. Among the candidate indicators, the P content of the tissues closely mirrored the two nutrient loading gradients. The epiphytic algae biomass and the N content in the tissues mirrored one of the two nutrient loading trends. The leaf length, however, exhibited a significant negative correlation with the nutrient gradients. We propose that changes in the P content of T. hemprichii, followed by epiphytic algae biomass and N content of the tissues, may be the useful indicators of nutrient loading to coastal ecosystems.

  17. Variations of leaf N and P concentrations in shrubland biomes across northern China: phylogeny, climate, and soil

    NASA Astrophysics Data System (ADS)

    Yang, Xian; Chi, Xiulian; Ji, Chengjun; Liu, Hongyan; Ma, Wenhong; Mohhammat, Anwar; Shi, Zhaoyong; Wang, Xiangping; Yu, Shunli; Yue, Ming; Tang, Zhiyao

    2016-08-01

    Concentrations of leaf nitrogen (N) and phosphorus (P) are two key traits of plants for ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on the stoichiometric patterns of trees and grasses, leaving a significant knowledge gap for shrubs. In this study, we explored the intraspecific and interspecific variations of leaf N and P concentrations in response to the changes in climate, soil property, and evolutionary history. We analysed 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China encompassing 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. Leaf N concentrations decreased with precipitation, while leaf P concentrations decreased with temperature and increased with precipitation and soil total P concentrations. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentrations were less conserved than leaf N concentrations. At the community level, climate explained more interspecific variation of leaf nutrient concentrations, while soil nutrients explained most of the intraspecific variation. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits. New patterns were discovered using our observations on specific regions and vegetation types, which improved our knowledge of broad biogeographic patterns of leaf chemical traits.

  18. Investigation of Biogeochemical Functional Proxies in Headwater Streams Across a Range of Channel and Catchment Alterations

    NASA Astrophysics Data System (ADS)

    Berkowitz, Jacob F.; Summers, Elizabeth A.; Noble, Chris V.; White, John R.; DeLaune, Ronald D.

    2014-03-01

    Historically, headwater streams received limited protection and were subjected to extensive alteration from logging, farming, mining, and development activities. Despite these alterations, headwater streams provide essential ecological functions. This study examines proxy measures of biogeochemical function across a range of catchment alterations by tracking nutrient cycling (i.e., inputs, processing, and stream loading) with leaf litter fall, leaf litter decomposition, and water quality parameters. Nutrient input and processing remained highest in second growth forests (the least altered areas within the region), while recently altered locations transported higher loads of nutrients, sediments, and conductivity. Biogeochemical functional proxies of C and N input and processing significantly, positively correlated with rapid assessment results (Pearson coefficient = 0.67-0.81; P = 0.002-0.016). Additionally, stream loading equations demonstrate that N and P transport, sediment, and specific conductivity negatively correlated with rapid assessment scores (Pearson coefficient = 0.56-0.81; P = 0.002-0.048). The observed increase in stream loading with lower rapid assessment scores indicates that catchment alterations impact stream chemistry and that rapid assessments provide useful proxy measures of function in headwater ecosystems. Significant differences in nutrient processing, stream loading, water quality, and rapid assessment results were also observed between recently altered (e.g., mined) headwater streams and older forested catchments (Mann-Whitney U = 24; P = 0.01-0.024). Findings demonstrate that biogeochemical function is reduced in altered catchments, and rapid assessment scores respond to a combination of alteration type and recovery time. An analysis examining time and economic requirements of proxy measurements highlights the benefits of rapid assessment methods in evaluating biogeochemical functions.

  19. Regulation of leaf hydraulics: from molecular to whole plant levels

    PubMed Central

    Prado, Karine; Maurel, Christophe

    2013-01-01

    The water status of plant leaves is dependent on both stomatal regulation and water supply from the vasculature to inner tissues. The present review addresses the multiple physiological and mechanistic facets of the latter process. Inner leaf tissues contribute to at least a third of the whole resistance to water flow within the plant. Physiological studies indicated that leaf hydraulic conductance (Kleaf) is highly dependent on the anatomy, development and age of the leaf and can vary rapidly in response to physiological or environmental factors such as leaf hydration, light, temperature, or nutrient supply. Differences in venation pattern provide a basis for variations in Kleaf during development and between species. On a short time (hour) scale, the hydraulic resistance of the vessels can be influenced by transpiration-induced cavitations, wall collapses, and changes in xylem sap composition. The extravascular compartment includes all living tissues (xylem parenchyma, bundle sheath, and mesophyll) that transport water from xylem vessels to substomatal chambers. Pharmacological inhibition and reverse genetics studies have shown that this compartment involves water channel proteins called aquaporins (AQPs) that facilitate water transport across cell membranes. In many plant species, AQPs are present in all leaf tissues with a preferential expression in the vascular bundles. The various mechanisms that allow adjustment of Kleaf to specific environmental conditions include transcriptional regulation of AQPs and changes in their abundance, trafficking, and intrinsic activity. Finally, the hydraulics of inner leaf tissues can have a strong impact on the dynamic responses of leaf water potential and stomata, and as a consequence on plant carbon economy and leaf expansion growth. The manipulation of these functions could help optimize the entire plant performance and its adaptation to extreme conditions over short and long time scales. PMID:23874349

  20. Strigolactone Regulates Leaf Senescence in Concert with Ethylene in Arabidopsis.

    PubMed

    Ueda, Hiroaki; Kusaba, Makoto

    2015-09-01

    Leaf senescence is not a passive degenerative process; it represents a process of nutrient relocation, in which materials are salvaged for growth at a later stage or to produce the next generation. Leaf senescence is regulated by various factors, such as darkness, stress, aging, and phytohormones. Strigolactone is a recently identified phytohormone, and it has multiple functions in plant development, including repression of branching. Although strigolactone is implicated in the regulation of leaf senescence, little is known about its molecular mechanism of action. In this study, strigolactone biosynthesis mutant strains of Arabidopsis (Arabidopsis thaliana) showed a delayed senescence phenotype during dark incubation. The strigolactone biosynthesis genes MORE AXIALLY GROWTH3 (MAX3) and MAX4 were drastically induced during dark incubation and treatment with the senescence-promoting phytohormone ethylene, suggesting that strigolactone is synthesized in the leaf during leaf senescence. This hypothesis was confirmed by a grafting experiment using max4 as the stock and Columbia-0 as the scion, in which the leaves from the Columbia-0 scion senesced earlier than max4 stock leaves. Dark incubation induced the synthesis of ethylene independent of strigolactone. Strigolactone biosynthesis mutants showed a delayed senescence phenotype during ethylene treatment in the light. Furthermore, leaf senescence was strongly accelerated by the application of strigolactone in the presence of ethylene and not by strigolactone alone. These observations suggest that strigolactone promotes leaf senescence by enhancing the action of ethylene. Thus, dark-induced senescence is regulated by a two-step mechanism: induction of ethylene synthesis and consequent induction of strigolactone synthesis in the leaf.

  1. Responses of leaf traits to climatic gradients: adaptive variation versus compositional shifts

    NASA Astrophysics Data System (ADS)

    Meng, T.-T.; Wang, H.; Harrison, S. P.; Prentice, I. C.; Ni, J.; Wang, G.

    2015-09-01

    Dynamic global vegetation models (DGVMs) typically rely on plant functional types (PFTs), which are assigned distinct environmental tolerances and replace one another progressively along environmental gradients. Fixed values of traits are assigned to each PFT; modelled trait variation along gradients is thus driven by PFT replacement. But empirical studies have revealed "universal" scaling relationships (quantitative trait variations with climate that are similar within and between species, PFTs and communities); and continuous, adaptive trait variation has been proposed to replace PFTs as the basis for next-generation DGVMs. Here we analyse quantitative leaf-trait variation on long temperature and moisture gradients in China with a view to understanding the relative importance of PFT replacement vs. continuous adaptive variation within PFTs. Leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC) and nitrogen content of dry matter were measured on all species at 80 sites ranging from temperate to tropical climates and from dense forests to deserts. Chlorophyll fluorescence traits and carbon, phosphorus and potassium contents were measured at 47 sites. Generalized linear models were used to relate log-transformed trait values to growing-season temperature and moisture indices, with or without PFT identity as a predictor, and to test for differences in trait responses among PFTs. Continuous trait variation was found to be ubiquitous. Responses to moisture availability were generally similar within and between PFTs, but biophysical traits (LA, SLA and LDMC) of forbs and grasses responded differently from woody plants. SLA and LDMC responses to temperature were dominated by the prevalence of evergreen PFTs with thick, dense leaves at the warm end of the gradient. Nutrient (N, P and K) responses to climate gradients were generally similar within all PFTs. Area-based nutrients generally declined with moisture; Narea and Karea declined with temperature

  2. Influence of Vegetation Structure on Lidar-derived Canopy Height and Fractional Cover in Forested Riparian Buffers During Leaf-Off and Leaf-On Conditions

    PubMed Central

    Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

    2013-01-01

    Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available. PMID:23382966

  3. Influence of vegetation structure on lidar-derived canopy height and fractional cover in forested riparian buffers during leaf-off and leaf-on conditions.

    PubMed

    Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

    2013-01-01

    Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available.

  4. Leaf litter disappearance in a tropical montane rain forest

    SciTech Connect

    La Caro, F.

    1982-03-01

    The time course of leaf litter disappearance of six rain forest tree species was monitored for 32 weeks at the El Verde lower montane rain forest study site in northeastern Puerto Rico. Dacryodes excelsa, Sloanea berteriana and Drypetes glauca were chosen to represent primary climax species while Cecropia peltata, Inga vera and Ixora ferrea were selected to represent the secondary successional species for this forest. The string non-confined tethered leaf method was employed in this study. Dry weights and concentrations of nitrogen, phosphorus, potassium, calcium and magnesium were determined through seven segments of time. Leaf litter fall and standing crop were estimated and general soil characteristics were measured to provide background data. The secondary species Cecropia peltata and Inga vera were found to have slower rates than the primary species Dacryodes excelsa and Sloanea berteriana. The same pattern appeared to emerge between the understory secondary Ixora ferrea and the understory primary Drypetes glauca. The interacting effects of the leaf structural characteristics such as % lignin and % fiber were found to be best correlated with the observed decay rates. Nutrients were considered important in establishing resource quality factors but did not appear to influence decay rates. Instead, nutrient dynamics reflected intervals of element immobilization, mineralization and importation. 82 refs., 13 figs., 12 tabs.

  5. Plants use macronutrients accumulated in leaf-cutting ant nests

    PubMed Central

    da S.L Sternberg, Leonel; Pinzon, Maria Camila; Moreira, Marcelo Z; Moutinho, Paulo; Rojas, Enith I; Herre, Edward Allen

    2006-01-01

    Leaf-cutting ants (Atta spp.) are known for their extensive defoliation in neo-tropical forests and savannahs. Debate about the costs and benefits of their activities has been largely dominated by their detrimental effects on agriculture and agroforestry. However, the large accumulation of nutrients and changes in soil properties near their nests might benefit plants growing near them. Here, we test whether trees use nutrients that accumulate in debris piles near, or refuse chambers within, leaf-cutting ant nests. At two tropical sites (a moist tropical forest site in Panama and a savannah site in Brazil), we fed leaves labelled with the stable isotope 15N to two species of leaf-cutting ants (Atta colombica and Atta laevigata) and traced the stable isotope label in plants surrounding the two nests. Thus, we show that plants in both sites access resources associated with Atta nests. In addition, leaf tissue of trees near the nests labelled with 15N had significantly higher calcium concentrations than those of distal, unlabelled conspecifics. It has been documented that calcium is a limiting macronutrient in tropical forests and savannahs. Atta may thus play an important ecological role through their long-distance transport, redistribution and concentration of critical macronutrients. PMID:17164194

  6. Leaf water oxygen isotope measurement by direct equilibration.

    PubMed

    Song, Xin; Barbour, Margaret M

    2016-08-01

    The oxygen isotope composition of leaf water imparts a signal to a range of molecules in the atmosphere and biosphere, but has been notoriously difficult to measure in studies requiring a large number of samples as a consequence of the labour-intensive extraction step. We tested a method of direct equilibration of water in fresh leaf samples with CO2 , and subsequent oxygen isotope analysis on an optical spectrometer. The oxygen isotope composition of leaf water measured by the direct equilibration technique was strongly linearly related to that of cryogenically extracted leaf water in paired samples for a wide range of species with differing anatomy, with an R(2) of 0.95. The somewhat more enriched values produced by the direct equilibration method may reflect lack of full equilibration with unenriched water in the vascular bundles, but the strong relationship across a wide range of species suggests that this difference can be adequately corrected for using a simple linear relationship.

  7. [Spectrum Variance Analysis of Tree Leaves Under the Condition of Different Leaf water Content].

    PubMed

    Wu, Jian; Chen, Tai-sheng; Pan, Li-xin

    2015-07-01

    Leaf water content is an important factor affecting tree spectral characteristics. So Exploring the leaf spectral characteristics change rule of the same tree under the condition of different leaf water content and the spectral differences of different tree leaves under the condition of the same leaf water content are not only the keys of hyperspectral vegetation remote sensing information identification but also the theoretical support of research on vegetation spectrum change as the differences in leaf water content. The spectrometer was used to observe six species of tree leaves, and the reflectivity and first order differential spectrum of different leaf water content were obtained. Then, the spectral characteristics of each tree species leaves under the condition of different leaf water content were analyzed, and the spectral differences of different tree species leaves under the condition of the same leaf water content were compared to explore possible bands of the leaf water content identification by hyperspectral remote sensing. Results show that the spectra of each tree leaf have changed a lot with the change of the leaf water content, but the change laws are different. Leaf spectral of different tree species has lager differences in some wavelength range under the condition of same leaf water content, and it provides some possibility for high precision identification of tree species.

  8. Nutrient Control Design Manual

    EPA Science Inventory

    The Nutrient Control Design Manual will present an extensive state-of-the-technology review of the engineering design and operation of nitrogen and phosphorous control technologies and techniques applied at municipal wastewater treatment plants (WWTPs). This manual will present ...

  9. Nutrient Control Seminars

    EPA Science Inventory

    These Nutrient Control Seminars will present an extensive state-of-the-technology review of the engineering design and operation of nitrogen and phosphorous control technologies and techniques applied at municipal wastewater treatment plants (WWTPs). These seminars will present ...

  10. Plants cause ecosystem nutrient depletion via the interruption of bird-derived spatial subsidies.

    PubMed

    Young, Hillary S; McCauley, Douglas J; Dunbar, Robert B; Dirzo, Rodolfo

    2010-02-01

    Plant introductions and subsequent community shifts are known to affect nutrient cycling, but most such studies have focused on nutrient enrichment effects. The nature of plant-driven nutrient depletions and the mechanisms by which these might occur are relatively poorly understood. In this study we demonstrate that the proliferation of the commonly introduced coconut palm, Cocos nucifera, interrupts the flow of allochthonous marine subsidies to terrestrial ecosystems via an indirect effect: impact on birds. Birds avoid nesting or roosting in C. nucifera, thus reducing the critical nutrient inputs they bring from the marine environment. These decreases in marine subsidies then lead to reductions in available soil nutrients, decreases in leaf nutrient quality, diminished leaf palatability, and reduced herbivory. This nutrient depletion pathway contrasts the more typical patterns of nutrient enrichment that follow plant species introductions. Research on the effects of spatial subsidy disruptions on ecosystems has not yet examined interruptions driven by changes within the recipient community, such as plant community shifts. The ubiquity of coconut palm introductions across the tropics and subtropics makes these observations particularly noteworthy. Equally important, the case of C. nucifera provides a strong demonstration of how plant community changes can dramatically impact the supply of allochthonous nutrients and thereby reshape energy flow in ecosystems. PMID:20133852

  11. Potential and realized nutrient resorption in serpentine and non-serpentine chaparral shrubs and trees.

    PubMed

    Drenovsky, Rebecca E; Koehler, Catherine E; Skelly, Kathryn; Richards, James H

    2013-01-01

    Low-nutrient adapted species have numerous mechanisms that aid in nutrient conservation. Hypothetically, species adapted to nutrient-poor soils should have tighter internal nutrient recycling, as evidenced by greater resorption. However, literature results are mixed. We suggest methodological factors may limit our understanding of this process. We hypothesized that plants adapted to serpentine soils would be more proficient in resorbing N and P than plants adapted to non-serpentine soils, although there would be differences among functional groups within each soil type. For six growing seasons, we sampled senescent leaf tissue from the dominant and co-dominant shrubs and trees found in serpentine and non-serpentine chaparral communities in the California Coast Range. Our study also explicitly included congener pairs found on both soil types. Most species were highly N proficient, but species adapted to serpentine soils were more P proficient. Surprisingly, two of the three potential N-fixing species were also highly N proficient. Evergreen Quercus congeners were more N proficient than their deciduous congener pairs, although there was no difference in P resorption proficiency. Overall, large inter-annual variation was observed among most species sampled, but at least in some years, maximum potential resorption likely was reached. However, climate (temperature and precipitation) was not strongly correlated with either N or P resorption proficiency. Our data suggest that controlling for phylogeny can aid in interpretation of resorption patterns. More importantly, our study clearly shows that resorption patterns can only be discerned through long-term datasets, of which few exist in the literature.

  12. Effect of boron nutrition on American ginseng in field and in nutrient cultures

    PubMed Central

    Proctor, John T.A.; Shelp, Barry J.

    2013-01-01

    Field and nutrient cultures of American ginseng (Panax quinquefolius L.) were used to establish foliar symptoms related to boron (B) concentration in leaves and soils, and to evaluate radish as a time-saving model system for B nutrition. Application of excess B, 8 kg/ha versus the recommended 1.5 kg/ha, to field plantings of 2-, 3-, and 4-yr-old American ginseng plants just prior to crop emergence caused, within 4 wk after crop emergence, leaf symptoms of chlorosis followed by necrosis starting at the tips and progressing along the margins. The B concentration in leaves of 2–4-yr-old plants receiving 1.5 kg/ha B was 30 μg/g dry mass compared to 460 μg/g dry mass where 8 kg/ha B was applied. Similarly, B concentration in soils receiving the lower B concentration was 1.8 μg/g dry mass and 2.2–2.8 μg/g dry mass where the higher B concentration was applied. Application of 8 kg/ha B reduced the dry yield of 3rd-yr roots by 20% from 2745 kg/ha to 2196 kg/ha and 4th-yr roots by 26% from 4130 kg/ha to 3071 kg/ha. Ginseng seedlings and radish were grown under greenhouse conditions in nutrient culture with four B concentrations ranging from 0 mg/L to 10 mg/L. At 5 mg/L and 10 mg/L ginseng and radish developed typical leaf B toxicity symptoms similar to those described above for field-grown plants. Increasing B in the nutrient solution from 0.5 mg/L to 10 mg/L decreased, in a linear fashion, the root and leaf dry mass of ginseng, but not radish. Given the many similarities of ginseng and radish to B utilization, radish might be used as a time-saving model system for the study of B, and other micronutrients, in the slow-growing perennial ginseng. PMID:24558314

  13. Effect of boron nutrition on American ginseng in field and in nutrient cultures.

    PubMed

    Proctor, John T A; Shelp, Barry J

    2014-01-01

    Field and nutrient cultures of American ginseng (Panax quinquefolius L.) were used to establish foliar symptoms related to boron (B) concentration in leaves and soils, and to evaluate radish as a time-saving model system for B nutrition. Application of excess B, 8 kg/ha versus the recommended 1.5 kg/ha, to field plantings of 2-, 3-, and 4-yr-old American ginseng plants just prior to crop emergence caused, within 4 wk after crop emergence, leaf symptoms of chlorosis followed by necrosis starting at the tips and progressing along the margins. The B concentration in leaves of 2-4-yr-old plants receiving 1.5 kg/ha B was 30 μg/g dry mass compared to 460 μg/g dry mass where 8 kg/ha B was applied. Similarly, B concentration in soils receiving the lower B concentration was 1.8 μg/g dry mass and 2.2-2.8 μg/g dry mass where the higher B concentration was applied. Application of 8 kg/ha B reduced the dry yield of 3rd-yr roots by 20% from 2745 kg/ha to 2196 kg/ha and 4th-yr roots by 26% from 4130 kg/ha to 3071 kg/ha. Ginseng seedlings and radish were grown under greenhouse conditions in nutrient culture with four B concentrations ranging from 0 mg/L to 10 mg/L. At 5 mg/L and 10 mg/L ginseng and radish developed typical leaf B toxicity symptoms similar to those described above for field-grown plants. Increasing B in the nutrient solution from 0.5 mg/L to 10 mg/L decreased, in a linear fashion, the root and leaf dry mass of ginseng, but not radish. Given the many similarities of ginseng and radish to B utilization, radish might be used as a time-saving model system for the study of B, and other micronutrients, in the slow-growing perennial ginseng. PMID:24558314

  14. How meristem plasticity in response to soil nutrients and light affects plant growth in four Festuca grass species.

    PubMed

    Sugiyama, Shu-ichi; Gotoh, Minako

    2010-02-01

    Investigation of responses of meristems to environmental conditions is important for understanding the mechanisms and consequences of plant phenotypic plasticity. Here, we examined how meristem plasticity to light and soil nutrients affected leaf growth and relative growth rate (RGR) in fast- and slow-growing Festuca grass species. Activity in shoot apical meristems was measured by leaf appearance rate, and that in leaf meristems by the duration and rate of cell production, which was further divided into single cell cycle time and the number of dividing cells. Light and soil nutrients affected activity in shoot apical meristems similarly. The high nutrient supply increased the number of dividing cells, which was responsible for enhancement of cell production rate; shaded conditions extended the duration of cell production. As a result, leaf length increased under high nutrient and shaded conditions. The RGR was correlated positively with the total meristem size of the shoot under a low nutrient supply, implying inhibition of RGR by cell production under nutrient-limited conditions. Fast-growing species were more plastic for cell production rate and specific leaf area (SLA) but less plastic for RGR than slow-growing species. This study demonstrates that meristem plasticity plays key roles in characterizing environmental responses of plant species.

  15. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies

    USGS Publications Warehouse

    Voelker, Steven L.; Brooks, J. Renée; Meinzer, Frederick C.; Anderson, Rebecca D.; Bader, Martin K.-F.; Battipaglia, Giovanna; Becklin, Katie M.; Beerling, David; Bert, Didier; Betancourt, Julio L.; Dawson, Todd E.; Domec, Jean-Christophe; Guyette, Richard P.; Körner, Christian; Leavitt, Steven W.; Linder, Sune; Marshall, John D.; Mildner, Manuel; Ogée, Jérôme; Panyushkina, Irina P.; Plumpton, Heather J.; Pregitzer, Kurt S.; Saurer, Matthias; Smith, Andrew R.; Siegwolf, Rolf T.W.; Stambaugh, Michael C.; Talhelm, Alan F.; Tardif, Jacques C.; Van De Water, Peter K.; Ward, Joy K.; Wingate, Lisa

    2016-01-01

    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 proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2], ci, a constant drawdown in CO2(ca − ci), and a constant ci/ca. These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca. The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca. To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ13C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca-induced changes in ci/ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca − ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci. Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca, when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca, when photosystems are saturated and water loss is large for each unit C gain.

  16. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2 : evidence from carbon isotope discrimination in paleo and CO2 enrichment studies.

    PubMed

    Voelker, Steven L; Brooks, J Renée; Meinzer, Frederick C; Anderson, Rebecca; Bader, Martin K-F; Battipaglia, Giovanna; Becklin, Katie M; Beerling, David; Bert, Didier; Betancourt, Julio L; Dawson, Todd E; Domec, Jean-Christophe; Guyette, Richard P; Körner, Christian; Leavitt, Steven W; Linder, Sune; Marshall, John D; Mildner, Manuel; Ogée, Jérôme; Panyushkina, Irina; Plumpton, Heather J; Pregitzer, Kurt S; Saurer, Matthias; Smith, Andrew R; Siegwolf, Rolf T W; Stambaugh, Michael C; Talhelm, Alan F; Tardif, Jacques C; Van de Water, Peter K; Ward, Joy K; Wingate, Lisa

    2016-02-01

    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 proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca  - ci ), and a constant ci /ca . These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca . The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca . To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ(13) C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca -induced changes in ci /ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca  - ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci . Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca , when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca , when photosystems are saturated and water loss is large for each unit C gain.

  17. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2 : evidence from carbon isotope discrimination in paleo and CO2 enrichment studies.

    PubMed

    Voelker, Steven L; Brooks, J Renée; Meinzer, Frederick C; Anderson, Rebecca; Bader, Martin K-F; Battipaglia, Giovanna; Becklin, Katie M; Beerling, David; Bert, Didier; Betancourt, Julio L; Dawson, Todd E; Domec, Jean-Christophe; Guyette, Richard P; Körner, Christian; Leavitt, Steven W; Linder, Sune; Marshall, John D; Mildner, Manuel; Ogée, Jérôme; Panyushkina, Irina; Plumpton, Heather J; Pregitzer, Kurt S; Saurer, Matthias; Smith, Andrew R; Siegwolf, Rolf T W; Stambaugh, Michael C; Talhelm, Alan F; Tardif, Jacques C; Van de Water, Peter K; Ward, Joy K; Wingate, Lisa

    2016-02-01

    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 proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca  - ci ), and a constant ci /ca . These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca . The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca . To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ(13) C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca -induced changes in ci /ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca  - ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant ci . Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca , when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca , when photosystems are saturated and water loss is large for each unit C gain

  18. Canopy leaf area constrains [CO2]-induced enhancement of productivity and partitioning among aboveground carbon pools

    PubMed Central

    McCarthy, Heather R.; Oren, Ram; Finzi, Adrien C.; Johnsen, Kurt H.

    2006-01-01

    Net primary productivity (NPP) is enhanced under future atmospheric [CO2] in temperate forests representing a broad range of productivity. Yet questions remain in regard to how elevated [CO2]-induced NPP enhancement may be affected by climatic variations and limiting nutrient resources, as well as how this additional production is distributed among carbon (C) pools of different longevities. Using 10 years of data from the Duke free-air CO2 enrichment (Duke FACE) site, we show that spatially, the major control of NPP was nitrogen (N) availability, through its control on canopy leaf area index (L). Elevated CO2 levels resulted in greater L, and thus greater NPP. After canopy closure had occurred, elevated [CO2] did not enhance NPP at a given L, regardless of soil water availability. Additionally, using published data from three other forest FACE sites and replacing L with leaf area duration (LD) to account for differences in growing season length, we show that aboveground NPP responded to [CO2] only through the enhancement of LD. For broadleaf forests, the fraction of aboveground NPP partitioned to wood biomass saturated with increasing LD and was not enhanced by [CO2], whereas it linearly decreased for the conifer forest but was enhanced by [CO2]. These results underscore the importance of resolving [CO2] effects on L to assess the response of NPP and C allocation. Further study is necessary to elucidate the mechanisms that control the differential allocation of C among aboveground pools in different forest types. PMID:17159159

  19. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  20. Spectra of normal and nutrient-deficient maize leaves

    NASA Technical Reports Server (NTRS)

    Al-Abbas, A. H.; Barr, R.; Hall, J. D.; Crane, F. L.; Baumgardner, M. F.

    1973-01-01

    Reflectance, transmittance and absorptance spectra of normal and six types of nutrient-deficient (N, P, K, S, Mg, and Ca) maize (Zea mays L.) leaves were analyzed at 30 selected wavelengths from 500 to 2600 nm. The analysis of variance showed significant differences in reflectance, transmittance and absorptance in the visible wavelengths among leaf numbers 3, 4, and 5, among the seven treatments, and among the interactions of leaf number and treatments. In the infrared wavelengths only treatments produced significant differences. The chlorophyll content of leaves was reduced in all nutrient-deficient treatments. Percent moisture was increased in S-, Mg-, and N-deficiencies. Polynomial regression analysis of leaf thickness and leaf moisture content showed that these two variables were significantly and directly related. Leaves from the P- and Ca-deficient plants absorbed less energy in the near infrared than the normal plants; S-, Mg-, K-, and N-deficient leaves absorbed more than the normal. Both S- and N-deficient leaves had higher temperatues than normal maize leaves.

  1. Evolution of the leaf economics spectrum in herbs: Evidence from environmental divergences in leaf physiology across Helianthus (Asteraceae).

    PubMed

    Mason, Chase M; Donovan, Lisa A

    2015-10-01

    The leaf economics spectrum (LES) describes a major axis of plant functional trait variation worldwide, defining suites of leaf traits aligned with resource-acquisitive to resource-conservative ecological strategies. The LES has been interpreted to arise from leaf-level trade-offs among ecophysiological traits common to all plants. However, it has been suggested that the defining leaf-level trade-offs of the LES may not hold within specific functional groups (e.g., herbs) nor within many groups of closely related species, which challenges the usefulness of the LES paradigm across evolutionary scales. Here, we examine the evolution of the LES across 28 species of the diverse herbaceous genus Helianthus (the sunflowers), which occupies a wide range of habitats and climate variation across North America. Using a phylogenetic comparative approach, we find repeated evolution of more resource-acquisitive LES strategies in cooler, drier, and more fertile environments. We also find macroevolutionary correlations among LES traits that recapitulate aspects of the global LES, but with one major difference: leaf mass per area is uncorrelated with leaf lifespan. This indicates that whole-plant processes likely drive variation in leaf lifespan across Helianthus, rather than leaf-level trade-offs. These results suggest that LES patterns do not reflect universal physiological trade-offs at small evolutionary scales.

  2. Intraspecific growth and functional leaf trait responses to natural soil resource gradients for conifer species with contrasting leaf habit.

    PubMed

    Walters, Michael B; Gerlach, John P

    2013-03-01

    Interspecific relationships among species mean leaf traits, performance and species resource/climate distributions help provide the foundation for a predictive, functionally based plant ecology. Intraspecific responses of leaf traits and performance to resource gradients and how these vary among species may be equally important but have received less attention. Here, we examine relationships between proxies of soil resource availability, leaf traits and growth (height at 25 years, SI25) for winter deciduous Larix decidua Mill. and evergreen Pinus resinosa Ait. trees distributed over soil resource gradients in the Great Lakes region of North America. We predicted that (i) leaf trait responses to soil resources within species will be similar to reported distributions of mean leaf traits over soil resource gradients among species; (ii) soil resource-related variation in leaf traits can help explain SI25; and (iii) SI25 will be greater for Larix than Pinus at higher soil resources and greater for Pinus than Larix at lower soil resources and this pattern will be associated with species differences in leaf trait responses to soil resources. Among the measured leaf traits (live N, Mg, Ca, K, P, and Mn, litter N, N resorption, carbon isotope discrimination, specific leaf area, lifespan), soil resources only impacted live and litter N for both species and K for Pinus. In turn, only the leaf traits responsive to soil resources affected SI25 in the expected manner. Larix had greater SI25 than Pinus across soil resource gradients and both species had similar growth and leaf trait sensitivities to resources. In summary: (i) several leaf traits reported to be associated with performance and edaphic distributions across species were, within species, unresponsive to nitrogen and water availability and unrelated to growth; (ii) leaf N showed high plasticity to soil resources and this plasticity was functionally relevant to growth over its entire range of response; (iii) large

  3. [Effects of organic fertilizer application rate on leaf photosynthetic characteristics and grain yield of dryland maize].

    PubMed

    Wang, Xiao-Juan; Jia, Zhi-Kuan; Liang, Lian-You; Ding, Rui-Xia; Wang, Min; Li, Han

    2012-02-01

    A 4-year field experiment was conducted at the Heyang Research Station in Weibei dryland to study the effects of organic fertilizer application rate on the leaf photosynthetic characteristics and grain yield of dryland maize. Comparing with applying chemical fertilizer, applying organic fertilizer increased the leaf photosynthetic rate and stomatal conductance, but decreased the leaf intercellular CO2 concentration at each growth stage of maize significantly. With the increasing application rate of organic fertilizer, the leaf photosynthetic rate and stomatal conductance at each growth stage of maize had a gradual increase, while the leaf intercellular CO2 concentration had a gradual decrease. The leaf photosynthesis of maize at each growth stage was controlled by non-stomatal factors, and the application of organic fertilizer reduced the non-stomatal limitation on the photosynthesis performance significantly. The 4-year application of organic fertilizer improved soil nutrient status, and soil nutrients were no longer the main factors limiting the leaf photosynthetic rate and grain yield of maize. PMID:22586967

  4. [Effects of organic fertilizer application rate on leaf photosynthetic characteristics and grain yield of dryland maize].

    PubMed

    Wang, Xiao-Juan; Jia, Zhi-Kuan; Liang, Lian-You; Ding, Rui-Xia; Wang, Min; Li, Han

    2012-02-01

    A 4-year field experiment was conducted at the Heyang Research Station in Weibei dryland to study the effects of organic fertilizer application rate on the leaf photosynthetic characteristics and grain yield of dryland maize. Comparing with applying chemical fertilizer, applying organic fertilizer increased the leaf photosynthetic rate and stomatal conductance, but decreased the leaf intercellular CO2 concentration at each growth stage of maize significantly. With the increasing application rate of organic fertilizer, the leaf photosynthetic rate and stomatal conductance at each growth stage of maize had a gradual increase, while the leaf intercellular CO2 concentration had a gradual decrease. The leaf photosynthesis of maize at each growth stage was controlled by non-stomatal factors, and the application of organic fertilizer reduced the non-stomatal limitation on the photosynthesis performance significantly. The 4-year application of organic fertilizer improved soil nutrient status, and soil nutrients were no longer the main factors limiting the leaf photosynthetic rate and grain yield of maize.

  5. Decomposition and nitrogen dynamics of 15N-labeled leaf, root, and twig litter in temperate coniferous forests

    USGS Publications Warehouse

    van Huysen, Tiff L.; Harmon, Mark E.; Perakis, Steven S.; Chen, Hua

    2013-01-01

    Litter nutrient dynamics contribute significantly to biogeochemical cycling in forest ecosystems. We examined how site environment and initial substrate quality influence decomposition and nitrogen (N) dynamics of multiple litter types. A 2.5-year decomposition study was installed in the Oregon Coast Range and West Cascades using 15N-labeled litter from Acer macrophyllum, Picea sitchensis, and Pseudotsuga menziesii. Mass loss for leaf litter was similar between the two sites, while root and twig litter exhibited greater mass loss in the Coast Range. Mass loss was greatest from leaves and roots, and species differences in mass loss were more prominent in the Coast Range. All litter types and species mineralized N early in the decomposition process; only A. macrophyllum leaves exhibited a net N immobilization phase. There were no site differences with respect to litter N dynamics despite differences in site N availability, and litter N mineralization patterns were species-specific. For multiple litter × species combinations, the difference between gross and net N mineralization was significant, and gross mineralization was 7–20 % greater than net mineralization. The mineralization results suggest that initial litter chemistry may be an important driver of litter N dynamics. Our study demonstrates that greater amounts of N are cycling through these systems than may be quantified by only measuring net mineralization and challenges current leaf-based biogeochemical theory regarding patterns of N immobilization and mineralization.

  6. Creating 13C- and 15N-enriched tree leaf litter for decomposition experiments

    NASA Astrophysics Data System (ADS)

    Szlavecz, K. A.; Pitz, S.; Chang, C.; Bernard, M.

    2013-12-01

    at the end of the experiment. Enrichment of roots was significantly higher than leaves (δ13C range: 111.5-219.2‰; δ15N range: 1516.9-3939.3‰) indicating that nutrients were translocated away from leaves prior to senescence, which is supported by the increase in C:N ratio between the initial (19.0) and final (60.1) leaf sampling. Despite the variable levels of enrichment, leaves from all species were sufficiently labeled for use in future studies aimed at tracking the transformation of carbon and nitrogen during decomposition. The greatest challenges were treating diseases and pests and creating ideal growing conditions for many species within the same chamber. Reducing the number of individuals and better pest management will lead to even higher level enrichment in the future.

  7. Genetic variability of Cotton leaf curl betasatellite in Northern India.

    PubMed

    Sohrab, Sayed Sartaj; Azhar, Esam I; Kamal, Mohammad A; Bhattacharya, P S; Rana, D

    2014-12-01

    Cotton is an important crop and its production is affected by various disease pathogens. Monopartite begomovirus associated betasatellites cause Cotton leaf curl disease (CLCuD) in Northern India. In order to access the occurrence and genetic variability of Cotton leaf curl betasatellites, an extensive field survey was conducted in states of Rajasthan, Punjab and Haryana. We selected the betasatellite sequence for analysis as they are reported as important for disease severity and sequence variability. Based on the field observations, the disease incidence ranged from 30% to 80% during the survey. Full genome and DNA β were amplified from various samples while no amplicon was obtained in some samples. The nucleotide sequence homology ranged from 90.0% to 98.7% with Cotton leaf curl virus (CLCuV), 55.2-55.5% with Bhendi yellow vein mosaic virus, 55.8% with Okra leaf curl virus and 51.70% with Tomato leaf curl virus isolates. The lowest similarity (47.8%) was found in CLCuV-Sudan isolate. Phylogenetic analysis showed that analyzed isolates formed a close cluster with various CLCuV isolates reported earlier. The analysis results show sequence variation in Cotton leaf curl betasatellite which could be the result of recombination. The results obtained by genome amplification and sequence variability indicate that some new variants are circulating and causing leaf curl disease in Rajasthan, Punjab and Haryana. PMID:25473373

  8. Macroecological and macroevolutionary patterns of leaf herbivory across vascular plants.

    PubMed

    Turcotte, Martin M; Davies, T Jonathan; Thomsen, Christina J M; Johnson, Marc T J

    2014-07-22

    The consumption of plants by animals underlies important evolutionary and ecological processes in nature. Arthropod herbivory evolved approximately 415 Ma and the ensuing coevolution between plants and herbivores is credited with generating much of the macroscopic diversity on the Earth. In contemporary ecosystems, herbivory provides the major conduit of energy from primary producers to consumers. Here, we show that when averaged across all major lineages of vascular plants, herbivores consume 5.3% of the leaf tissue produced annually by plants, whereas previous estimates are up to 3.8× higher. This result suggests that for many plant species, leaf herbivory may play a smaller role in energy and nutrient flow than currently thought. Comparative analyses of a diverse global sample of 1058 species across 2085 populations reveal that models of stabilizing selection best describe rates of leaf consumption, and that rates vary substantially within and among major plant lineages. A key determinant of this variation is plant growth form, where woody plant species experience 64% higher leaf herbivory than non-woody plants. Higher leaf herbivory in woody species supports a key prediction of the plant apparency theory. Our study provides insight into how a long history of coevolution has shaped the ecological and evolutionary relationships between plants and herbivores.

  9. Macroecological and macroevolutionary patterns of leaf herbivory across vascular plants

    PubMed Central

    Turcotte, Martin M.; Davies, T. Jonathan; Thomsen, Christina J. M.; Johnson, Marc T. J.

    2014-01-01

    The consumption of plants by animals underlies important evolutionary and ecological processes in nature. Arthropod herbivory evolved approximately 415 Ma and the ensuing coevolution between plants and herbivores is credited with generating much of the macroscopic diversity on the Earth. In contemporary ecosystems, herbivory provides the major conduit of energy from primary producers to consumers. Here, we show that when averaged across all major lineages of vascular plants, herbivores consume 5.3% of the leaf tissue produced annually by plants, whereas previous estimates are up to 3.8× higher. This result suggests that for many plant species, leaf herbivory may play a smaller role in energy and nutrient flow than currently thought. Comparative analyses of a diverse global sample of 1058 species across 2085 populations reveal that models of stabilizing selection best describe rates of leaf consumption, and that rates vary substantially within and among major plant lineages. A key determinant of this variation is plant growth form, where woody plant species experience 64% higher leaf herbivory than non-woody plants. Higher leaf herbivory in woody species supports a key prediction of the plant apparency theory. Our study provides insight into how a long history of coevolution has shaped the ecological and evolutionary relationships between plants and herbivores. PMID:24870043

  10. [Effects of sandy land water habitat and years after rejuvenation pruning on leaf functional traits of Salix psammophila].

    PubMed

    Zhang, Ping-ping; Li, Yang-yang; Shao, Ming-an

    2011-09-01

    This paper studied the effects of habitats (riparian inter-dune and dry top dune) and years after rejuvenation pruning (1, 2, 3-4, and 5-6 years) on the leaf functional traits (gas exchange, water use efficiency, structural traits, and N and P contents) of Salix psammophila growing in the southern edge of Mu Us Sandy Land. In the habitat of riparian inter-dune, the leaf net photosynthetic rate, stomatal conductance, and instantaneous and long-term water use efficiencies were all higher, while the leaf N and P contents were lower, as compared with those in the habitat of dry top dune. No significant differences were observed in the leaf structural traits between the two habitats, suggesting that S. psammophila could survive in a dry habitat by the strategies of increasing nutrient uptake and decreasing photosynthesis and water use. With the increasing years after rejuvenation pruning, the leaf net photosynthetic rate and stomatal conductance decreased significantly, and the leaf N content and instantaneous water use efficiency also showed a decreasing trend, with a positive correlation between them. One-year after rejuvenation pruning, the leaf area was the highest, and the specific leaf mass and leaf dry matter content were the lowest. Thereafter, the leaf area and dry matter content had no obvious change, but the specific leaf mass increased with increasing years after rejuvenation pruning. There were no significant correlations between leaf structural traits and photosynthetic and nutrient traits, suggesting that the decreases of leaf photosynthetic capacity and N content were the major reasons for S. psammophila senescence with increasing years after rejuvenation pruning.

  11. Effects of precipitation regime and soil nitrogen on leaf traits in seasonally dry tropical forests of the Yucatan Peninsula, Mexico.

    PubMed

    Roa-Fuentes, Lilia L; Templer, Pamela H; Campo, Julio

    2015-10-01

    Leaf traits are closely associated with nutrient use by plants and can be utilized as a proxy for nutrient cycling processes. However, open questions remain, in particular regarding the variability of leaf traits within and across seasonally dry tropical forests. To address this, we considered six leaf traits (specific area, thickness, dry matter content, N content, P content and natural abundance (15)N) of four co-occurring tree species (two that are not associated with N2-fixing bacteria and two that are associated with N2-fixing bacteria) and net N mineralization rates and inorganic N concentrations along a precipitation gradient (537-1036 mm per year) in the Yucatan Peninsula, Mexico. Specifically we sought to test the hypothesis that leaf traits of dominant plant species shift along a precipitation gradient, but are affected by soil N cycling. Although variation among different species within each site explains some leaf trait variation, there is also a high level of variability across sites, suggesting that factors other than precipitation regime more strongly influence leaf traits. Principal component analyses indicated that across sites and tree species, covariation in leaf traits is an indicator of soil N availability. Patterns of natural abundance (15)N in foliage and foliage minus soil suggest that variation in precipitation regime drives a shift in plant N acquisition and the openness of the N cycle. Overall, our study shows that both plant species and site are important determinants of leaf traits, and that the leaf trait spectrum is correlated with soil N cycling.

  12. Leaf chlorophyll constraint on model simulated gross primary productivity in agricultural systems

    NASA Astrophysics Data System (ADS)

    Houborg, Rasmus; F. McCabe, Matthew; Cescatti, Alessandro; A. Gitelson, Anatoly

    2015-12-01

    Leaf chlorophyll content (Chll) may serve as an observational proxy for the maximum rate of carboxylation (Vmax), which describes leaf photosynthetic capacity and represents the single most important control on modeled leaf photosynthesis within most Terrestrial Biosphere Models (TBMs). The parameterization of Vmax is associated with great uncertainty as it can vary significantly between plants and in response to changes in leaf nitrogen (N) availability, plant phenology and environmental conditions. Houborg et al. (2013) outlined a semi-mechanistic relationship between Vmax25 (Vmax normalized to 25 °C) and Chll based on inter-linkages between Vmax25, Rubisco enzyme kinetics, N and Chll. Here, these relationships are parameterized for a wider range of important agricultural crops and embedded within the leaf photosynthesis-conductance scheme of the Community Land Model (CLM), bypassing the questionable use of temporally invariant and broadly defined plant functional type (PFT) specific Vmax25 values. In this study, the new Chll constrained version of CLM is refined with an updated parameterization scheme for specific application to soybean and maize. The benefit of using in-situ measured and satellite retrieved Chll for constraining model simulations of Gross Primary Productivity (GPP) is evaluated over fields in central Nebraska, U.S.A between 2001 and 2005. Landsat-based Chll time-series records derived from the Regularized Canopy Reflectance model (REGFLEC) are used as forcing to the CLM. Validation of simulated GPP against 15 site-years of flux tower observations demonstrate the utility of Chll as a model constraint, with the coefficient of efficiency increasing from 0.91 to 0.94 and from 0.87 to 0.91 for maize and soybean, respectively. Model performances particularly improve during the late reproductive and senescence stage, where the largest temporal variations in Chll (averaging 35-55 μg cm-2 for maize and 20-35 μg cm-2 for soybean) are observed. While

  13. Anthropogenic nutrients and harmful algae in coastal waters.

    PubMed

    Davidson, Keith; Gowen, Richard J; Harrison, Paul J; Fleming, Lora E; Hoagland, Porter; Moschonas, Grigorios

    2014-12-15

    Harmful algal blooms (HABs) are thought to be increasing in coastal waters worldwide. Anthropogenic nutrient enrichment has been proposed as a principal causative factor of this increase through elevated inorganic and/or organic nutrient concentrations and modified nutrient ratios. We assess: 1) the level of understanding of the link between the amount, form and ratio of anthropogenic nutrients and HABs; 2) the evidence for a link between anthropogenically generated HABs and negative impacts on human health; and 3) the economic implications of anthropogenic nutrient/HAB interactions. We demonstrate that an anthropogenic nutrient-HAB link is far from universal, and where it has been demonstrated, it is most frequently associated with high biomass rather than low biomass (biotoxin producing) HABs. While organic nutrients have been shown to support the growth of a range of HAB species, insufficient evidence exists to clearly establish if these nutrients specifically promote the growth of harmful species in preference to benign ones, or if/how they influence toxicity of harmful species. We conclude that the role of anthropogenic nutrients in promoting HABs is site-specific, with hydrodynamic processes often determining whether blooms occur. We also find a lack of evidence of widespread significant adverse health impacts from anthropogenic nutrient-generated HABs, although this may be partly due to a lack of human/animal health and HAB monitoring. Detailed economic evaluation and cost/benefit analysis of the impact of anthropogenically generated HABs, or nutrient reduction schemes to alleviate them, is also frequently lacking.

  14. Anthropogenic nutrients and harmful algae in coastal waters.

    PubMed

    Davidson, Keith; Gowen, Richard J; Harrison, Paul J; Fleming, Lora E; Hoagland, Porter; Moschonas, Grigorios

    2014-12-15

    Harmful algal blooms (HABs) are thought to be increasing in coastal waters worldwide. Anthropogenic nutrient enrichment has been proposed as a principal causative factor of this increase through elevated inorganic and/or organic nutrient concentrations and modified nutrient ratios. We assess: 1) the level of understanding of the link between the amount, form and ratio of anthropogenic nutrients and HABs; 2) the evidence for a link between anthropogenically generated HABs and negative impacts on human health; and 3) the economic implications of anthropogenic nutrient/HAB interactions. We demonstrate that an anthropogenic nutrient-HAB link is far from universal, and where it has been demonstrated, it is most frequently associated with high biomass rather than low biomass (biotoxin producing) HABs. While organic nutrients have been shown to support the growth of a range of HAB species, insufficient evidence exists to clearly establish if these nutrients specifically promote the growth of harmful species in preference to benign ones, or if/how they influence toxicity of harmful species. We conclude that the role of anthropogenic nutrients in promoting HABs is site-specific, with hydrodynamic processes often determining whether blooms occur. We also find a lack of evidence of widespread significant adverse health impacts from anthropogenic nutrient-generated HABs, although this may be partly due to a lack of human/animal health and HAB monitoring. Detailed economic evaluation and cost/benefit analysis of the impact of anthropogenically generated HABs, or nutrient reduction schemes to alleviate them, is also frequently lacking. PMID:25173729

  15. Integrated Urban Nutrient Management

    NASA Astrophysics Data System (ADS)

    Nhapi, I.; Veenstra, S.; Siebel, M. A.; Gijzen, H. J.

    Most cities, especially from the developing countries, are facing serious problems with the management of nutrients, necessitating an urgent review of current waste management systems. Whilst highly efficient technologies are available, the inclusion of these in a well-thought out and systematic approach is necessary to contain the nutrient influxes and outfluxes from towns. Five intervention measures are proposed in this paper. The first is to manage the use and generation of nutrients by drastically minimising water consumption and employing other cleaner production approaches. The second deals with the optimal reuse of nutrients and water at the smallest possible level, like at the household and on-plot level. The second option is to covert the waste into something useful for reuse, and, where not possible, to something which is envi- ronmentally neutral. This involves treatment, but applying technologies that makes the best use of side products via reuse. Where the first three options will have failed, two least preferred options could be used. Waste can be dispersed or diluted to enhance self-purification capacities of downstream water bodies. The last option is to store the wastewater for some parts of the year when there is water shortage to allow for polishing during the standing period. The success of urban nutrient planning requires an integrated approach, proving specific solutions to specific situations. This, in turn, requires appropriate institutional responses.

  16. Water Relations, Gas Exchange, and Nutrient Response to a Long Term Constant Water Deficit

    NASA Technical Reports Server (NTRS)

    Berry, Wade L.; Goldstein, Guillermo; Dreschel, Thomas W.; Wheeler, Raymond M.; Sager, John C.; Knott, William M.

    1992-01-01

    Wheat plants (Triticum aestivum) were grown for 43 days in a micro-porous tube nutrient delivery system. Roots were unable to penetrate the microporous tube, but grew on the surface and maintained capillary contact with the nutrient solution on the inside of the tube through the 5-micron pores of the porous tube. Water potential in the system was controlled at -0.4, -0.8, and -3.0 kPa by adjusting the applied pressure (hydrostatic head) to the nutrient solution flowing through the microporous tubes. A relatively small decrease in applied water potential from -0.4 to -3.0 kPa resulted in a 34% reduction of shoot growth but only a moderate reduction in the midday leaf water potential from -1.3 to -1.7 MPa. Carbon dioxide assimilation decreased and water use efficiency increased with the more negative applied water potentials, while intercellular CO2 concentration remained constant. This was associated with a decrease in stomatal conductance to water vapor from 1.90 to 0.98 mol/(sq m sec) and a decrease in total apparent hydraulic conductance from 47 to 12 (micro)mol/(sec MPa). Although the applied water potentials were in the -0.4 to -3.0 kPa range, the actual water potential perceived by the plant roots appeared to be in the range of -0.26 to -0.38 MPa as estimated by the leaf water potential of bagged plants. The amount of K, Ca, Mg, Zn, Cu, and B accumulated with each unit of transpired water increased as the applied water potential became less negative. The increase in accumulation ranged from 1.4-fold for K to 2.2-fold for B. The physiological responses observed in this study in response to small constant differences in applied water potentials were much greater than expected from either the applied water potential or the observed plant water potential. Even though the micro-porous tube may not represent natural conditions and could possibly introduce morphological and physiological artifacts, it enables a high degree of control of water potential that

  17. Climatic Controls on Leaf Nitrogen Content and Implications for Biochemical Modeling.

    NASA Astrophysics Data System (ADS)

    Tcherednichenko, I. A.; White, M.; Bastidas, L.

    2007-12-01

    Leaf nitrogen (N) content, expressed as percent total nitrogen per unit of leaf dry mass, is a widely used parameter in biochemical modeling, due mainly to its role as a potentially limiting factor for photosynthesis. The amount of nitrogen, however, does not occur in a fixed amount in every leaf, but rather varies continuously with the leaf life cycle, in constant response to soil-root-stem-leaf-climate interactions and demand for growth. Moreover, while broad data on leaf N has become available it is normally measured under ambient conditions with consequent difficulty for distinguishing between genetic and time specific environmental effects. In the present work we: 1) Investigate the theoretical variation of leaf mass, specific heat capacity and leaf thickness of full sun-expanded leaves as a regulatory mechanism to ensure thermal survival along with long-term climatic radiation/temperature gradient; and discuss nitrogen and carbon controls on leaf thickness. 2) Based on possible states of partition between nitrogenous and non-nitrogenous components of a leaf we further derive probability density functions (PDFs) of nitrogen and carbon content and assess the effect of water and nutrient uptake on the PDFs. 3) Translate the results to spatially explicit representation over the conterminous USA at 1 km spatial resolution by providing maximum potential values of leaf N of fully expanded leaf optimally suited for long term climatic averages values and soils conditions. Implications for potential presence of inherently slow/fast growing species are discussed along with suitability of results for use by biochemical models.

  18. Leaf Dynamics of Panicum maximum under Future Climatic Changes.

    PubMed

    Britto de Assis Prado, Carlos Henrique; Haik Guedes de Camargo-Bortolin, Lívia; Castro, Érique; Martinez, Carlos Alberto

    2016-01-01

    Panicum maximum Jacq. 'Mombaça' (C4) was grown in field conditions with sufficient water and nutrients to examine the effects of warming and elevated CO2 concentrations during the winter. Plants were exposed to either the ambient temperature and regular atmospheric CO2 (Control); elevated CO2 (600 ppm, eC); canopy warming (+2°C above regular canopy temperature, eT); or elevated CO2 and canopy warming (eC+eT). The temperatures and CO2 in the field were controlled by temperature free-air controlled enhancement (T-FACE) and mini free-air CO2 enrichment (miniFACE) facilities. The most green, expanding, and expanded leaves and the highest leaf appearance rate (LAR, leaves day(-1)) and leaf elongation rate (LER, cm day(-1)) were observed under eT. Leaf area and leaf biomass were higher in the eT and eC+eT treatments. The higher LER and LAR without significant differences in the number of senescent leaves could explain why tillers had higher foliage area and leaf biomass in the eT treatment. The eC treatment had the lowest LER and the fewest expanded and green leaves, similar to Control. The inhibitory effect of eC on foliage development in winter was indicated by the fewer green, expanded, and expanding leaves under eC+eT than eT. The stimulatory and inhibitory effects of the eT and eC treatments, respectively, on foliage raised and lowered, respectively, the foliar nitrogen concentration. The inhibition of foliage by eC was confirmed by the eC treatment having the lowest leaf/stem biomass ratio and by the change in leaf biomass-area relationships from linear or exponential growth to rectangular hyperbolic growth under eC. Besides, eC+eT had a synergist effect, speeding up leaf maturation. Therefore, with sufficient water and nutrients in winter, the inhibitory effect of elevated CO2 on foliage could be partially offset by elevated temperatures and relatively high P. maximum foliage production could be achieved under future climatic change. PMID:26894932

  19. Leaf Dynamics of Panicum maximum under Future Climatic Changes

    PubMed Central

    Britto de Assis Prado, Carlos Henrique; Haik Guedes de Camargo-Bortolin, Lívia; Castro, Érique; Martinez, Carlos Alberto

    2016-01-01

    Panicum maximum Jacq. ‘Mombaça’ (C4) was grown in field conditions with sufficient water and nutrients to examine the effects of warming and elevated CO2 concentrations during the winter. Plants were exposed to either the ambient temperature and regular atmospheric CO2 (Control); elevated CO2 (600 ppm, eC); canopy warming (+2°C above regular canopy temperature, eT); or elevated CO2 and canopy warming (eC+eT). The temperatures and CO2 in the field were controlled by temperature free-air controlled enhancement (T-FACE) and mini free-air CO2 enrichment (miniFACE) facilities. The most green, expanding, and expanded leaves and the highest leaf appearance rate (LAR, leaves day-1) and leaf elongation rate (LER, cm day-1) were observed under eT. Leaf area and leaf biomass were higher in the eT and eC+eT treatments. The higher LER and LAR without significant differences in the number of senescent leaves could explain why tillers had higher foliage area and leaf biomass in the eT treatment. The eC treatment had the lowest LER and the fewest expanded and green leaves, similar to Control. The inhibitory effect of eC on foliage development in winter was indicated by the fewer green, expanded, and expanding leaves under eC+eT than eT. The stimulatory and inhibitory effects of the eT and eC treatments, respectively, on foliage raised and lowered, respectively, the foliar nitrogen concentration. The inhibition of foliage by eC was confirmed by the eC treatment having the lowest leaf/stem biomass ratio and by the change in leaf biomass-area relationships from linear or exponential growth to rectangular hyperbolic growth under eC. Besides, eC+eT had a synergist effect, speeding up leaf maturation. Therefore, with sufficient water and nutrients in winter, the inhibitory effect of elevated CO2 on foliage could be partially offset by elevated temperatures and relatively high P. maximum foliage production could be achieved under future climatic change. PMID:26894932

  20. Leaf physiological processes strongly affect δH2 values of leaf wax n-alkanes in C3 and C4 grasses.

    NASA Astrophysics Data System (ADS)

    Gamarra, Bruno; Sachse, Dirk; Kahmen, Ansgar

    2013-04-01

    species specific, e.g. for D. glomerata the influence of leaf water evaporative Deuterium-enrichment on leaf wax n-alkanes δH2 values was about 100%; but for other species the influence ranged from 25 to 90%. In our presentation we will relate these different contributions of leaf water δH2 values to differences in species' morphology and/or physiology. Key words: plant physiology, stable hydrogen isotopes, evaporative H2-enrichment, leaf wax n-alkanes, paleoclimate

  1. Spectral characteristics of normal and nutrient-deficient maize leaves

    NASA Technical Reports Server (NTRS)

    Al-Abbas, A. H.; Barr, R.; Hall, J. D.; Crane, F. L.; Baumgardner, M. F.

    1972-01-01

    Reflectance, transmittance and absorbance spectra of normal and six types of mineral-deficient (N,P,K,S,Mg and Ca) maize (Zea mays L.) leaves were analyzed at 30 selected wavelengths along the electromagnetic spectrum from 500 to 2600 nm. Chlorophyll content and percent leaf moisture were also determined. Leaf thermograms were obtained for normal, N- and S- deficient leaves. The results of the analysis of variance showed significant differences in reflectance, transmittance and absorbance in the visible wavelengths among leaf numbers 3, 4, and 5, among the seven nutrient treatments, and among the interactions of leaves and treatments. In the reflective infrared wavelengths only treatments produced significant differences. The chlorophyll content of leaves was reduced in all deficiencies in comparison to controls. Percent moisture was increased in S-, Mg- and N- deficiencies. Positive correlation (r = 0.707) between moisture content and percent absorption at both 1450 and 1930 nm were obtained. Polynomial regression analysis of leaf thickness and leaf moisture content showed that these two variables were significantly and directly related (r = 0.894).

  2. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  3. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  4. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  5. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  6. Nutrient management effects on sweetpotato genotypes under controlled environment

    NASA Technical Reports Server (NTRS)

    David, P. P.; Bonsi, C. K.; Trotman, A. A.; Douglas, D. Z.

    1996-01-01

    Sweetpotato is one of several crops recommended by National Aeronautics and Space Administration (NASA) for bioregenerative life support studies. One of the objectives of the Tuskegee University NASA Center is to optimize growth conditions for adaptability of sweetpotatoes for closed bioregenerative systems. The role of nutrient solution management as it impacts yield has been one of the major thrusts in these studies. Nutrient solution management protocol currently used consists of a modified half Hoagland solution that is changed at 14-day intervals. Reservoirs are refilled with deionized water if the volume of the nutrient solution was reduced to 8 liters or less before the time of solution change. There is the need to recycle and replenish nutrient solution during crop growth, rather than discard at 14 day intervals as previously done, in order to reduce waste. Experiments were conducted in an environmental growth room to examine the effects of container size on the growth of several sweetpotato genotypes grown under a nutrient replenishment protocol. Plants were grown from vine cuttings of 15cm length and were planted in 0.15 x 0.15 x 1.2m growth channels using a closed nutrient film technique system. Nutrient was supplied in a modified half strength Hoagland's solution with a 1:2.4 N:K ratio. Nutrient replenishment protocol consisted of daily water replenishment to a constant volume of 30.4 liters in the small containers and 273.6 liters in the large container. Nutrients were replenished as needed when the EC of the nutrient solution fell below 1200 mhos/cm. The experimental design used was a split-plot with the main plot being container size and genotypes as the subplot. Nine sweetpotato genotypes were evaluated. Results showed no effect of nutrient solution container size on storage root yield, foliage fresh and dry mass, leaf area or vine length. However, plants grown using the large nutrient solution container accumulated more storage root dry mass than

  7. [Anatomical and nutrient features of plant leaves in Yuanjiang savanna valley].

    PubMed

    Song, Fuqiang; Cao, Kunfang

    2005-01-01

    Due to rain shadow effect, the valleys in southwestern China mountainous areas have hot and dry climate, and savanna or semi-savanna vegetations occur on the slopes of these valleys. Yuanjiang dry-hot valley is such a valley, which has a distinct dry season of about six months from November to next April. This paper studied the anatomical and nutrient features of the leaves of twenty plant species, including those on upland soils and hilly slopes. The results showed that compared with the species on upland soil and the rain forest, the leaves of the plants from savanna showed more xeromorphic features, such as thicker leaf thickness, greater leaf mass per area (LMA), smaller ratios of spongy/palisade tissues (S:P) and higher stomatal density (SD), which mainly came from the more severe drought in Yuanjiang savanna valley. Seven plant species in the savanna valley showed a shortage of nutrients in their leaves, and the leaf nutrient content was in order of 1.3% > Ca > N > K > 1% > Mg > P > S. Savanna had lower leaf mineral element concentrations than rain forest, but higher than other dry forests, including Asian heath forest and Bana forest. The differences in leaf nutrient concentrations between Yuanjiang valley savanna and other dry forests were mainly ascribed to the difference of soil nutrient contents, while those between valley savanna and rainforest were largely determined by the different plant biology. It could be concluded that the leaves of plant species in Yuanjiang savanna valley not only had obvious xeromorphic features, but also were deficit in nutrients. PMID:15852953

  8. Drought-deciduous behavior reduces nutrient losses from temperate deciduous trees under severe drought.

    PubMed

    Marchin, Renée; Zeng, Hainian; Hoffmann, William

    2010-08-01

    Nutrient resorption from senescing leaves is an important mechanism of nutrient conservation in temperate deciduous forests. Resorption, however, may be curtailed by climatic events that cause rapid leaf death, such as severe drought, which has been projected to double by the year 2100 in the eastern United States. During a record drought in the southeastern US, we studied 18 common temperate winter-deciduous trees and shrubs to understand how extreme drought affects nutrient resorption of the macronutrients N, P, K, and Ca. Four species exhibited drought-induced leaf senescence and maintained higher leaf water potentials than the remaining 14 species (here called drought-evergreen species). This strategy prevented extensive leaf desiccation during the drought and successfully averted large nutrient losses caused by leaf desiccation. These four drought-deciduous species were also able to resorb N, P, and K from drought-senesced leaves, whereas drought-evergreen species did not resorb any nutrients from leaves lost to desiccation during the drought. For Oxydendrum arboreum, the species most severely affected by the drought, our results indicate that trees lost 50% more N and P due to desiccation than would have been lost from fall senescence alone. For all drought-deciduous species, resorption of N and P in fall-senesced leaves was highly proficient, whereas resorption was incomplete for drought-evergreen species. The lower seasonal nutrient losses of drought-deciduous species may give them a competitive advantage over drought-evergreen species in the years following the drought, thereby impacting species composition in temperate deciduous forests in the future.

  9. [Anatomical and nutrient features of plant leaves in Yuanjiang savanna valley].

    PubMed

    Song, Fuqiang; Cao, Kunfang

    2005-01-01

    Due to rain shadow effect, the valleys in southwestern China mountainous areas have hot and dry climate, and savanna or semi-savanna vegetations occur on the slopes of these valleys. Yuanjiang dry-hot valley is such a valley, which has a distinct dry season of about six months from November to next April. This paper studied the anatomical and nutrient features of the leaves of twenty plant species, including those on upland soils and hilly slopes. The results showed that compared with the species on upland soil and the rain forest, the leaves of the plants from savanna showed more xeromorphic features, such as thicker leaf thickness, greater leaf mass per area (LMA), smaller ratios of spongy/palisade tissues (S:P) and higher stomatal density (SD), which mainly came from the more severe drought in Yuanjiang savanna valley. Seven plant species in the savanna valley showed a shortage of nutrients in their leaves, and the leaf nutrient content was in order of 1.3% > Ca > N > K > 1% > Mg > P > S. Savanna had lower leaf mineral element concentrations than rain forest, but higher than other dry forests, including Asian heath forest and Bana forest. The differences in leaf nutrient concentrations between Yuanjiang valley savanna and other dry forests were mainly ascribed to the difference of soil nutrient contents, while those between valley savanna and rainforest were largely determined by the different plant biology. It could be concluded that the leaves of plant species in Yuanjiang savanna valley not only had obvious xeromorphic features, but also were deficit in nutrients.

  10. Source of Boron in Curcuma for Burn Symptoms at Leaf Margins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was initiated to investigate the source of boron (B) accumulated in margins of leaves of Curcuma ‘Chiangmai University Pride (‘CMU Pride’). Nutrient elements were analyzed from different rhizome locations before potting, and from whole rhizomes and different leaf locations at harvest af...

  11. Genome Sequence of a Xylella fastidiosa Strain Causing Mulberry Leaf Scorch Disease in Maryland.

    PubMed

    Guan, Wei; Shao, Jonathan; Zhao, Tingchang; Huang, Qi

    2014-01-01

    Xylella fastidiosa causes bacterial leaf scorch in landscape trees, including mulberry. We determined the draft genome of the mulberry strain Mul-MD in order to gain a better understanding of the molecular basis of strain divergence, host specificity, nutrient requirements, and pathogenicity, as well as to develop genome-based specific detection methods. PMID:24604658

  12. Effect of Greens and Soil Type, Sulfur Addition and Lithium Level on Leaf Constituents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A greenhouse experiment was conducted near Weslaco, Texas (Lat. 26o 8' N, Long. 97o 57' W) between Dec. 2006 and Feb 2007 to evaluate the effect of soil type, added sulfur and lithium level on the growth and leaf nutrients, particularly biofortified levels of Li and S, in spinach and mustard gree...

  13. A rapid leaf-disc sampler for psychrometric water potential measurements.

    PubMed

    Wullschleger, S D; Oosterhuis, D M

    1986-06-01

    An instrument was designed which facilitates faster and more accurate sampling of leaf discs for psychrometric water potential measurements. The instrument consists of an aluminum housing, a spring-loaded plunger, and a modified brass-plated cork borer. The leaf-disc sampler was compared with the conventional method of sampling discs for measurement of leaf water potential with thermocouple psychrometers on a range of plant material including Gossypium hirsutum L., Zea mays L., and Begonia rex-cultorum L. The new sampler permitted a leaf disc to be excised and inserted into the psychrometer sample chamber in less than 7 seconds, which was more than twice as fast as the conventional method. This resulted in more accurate determinations of leaf water potential due to reduced evaporative water losses. The leaf-disc sampler also significantly reduced sample variability between individual measurements. This instrument can be used for many other laboratory and field measurements that necessitate leaf disc sampling. PMID:16664879

  14. The relationship between leaf water status, gas exchange, and spectral reflectance in cotton leaves

    NASA Technical Reports Server (NTRS)

    Bowman, William D.

    1989-01-01

    Measurements of leaf spectral reflectance, the components of water potential, and leaf gas exchanges as a function of leaf water content were made to evaluate the use of NIR reflectance as an indicator of plant water status. Significant correlations were determined between spectral reflectance at 810 nm, 1665 nm, and 2210 nm and leaf relative water content, total water potential, and turgor pressure. However, the slopes of these relationships were relatively shallow and, when evaluated over the range of leaf water contents in which physiological activity occurs (e.g., photosynthesis), had lower r-squared values, and some relationships were not statistically significant. NIR reflectance varied primarily as a function of leaf water content, and not independently as a function of turgor pressure, which is a sensitive indicator of leaf water status. The limitations of this approach to measuring plant water stress are discussed.

  15. Narrow grass hedge effects on nutrient transport following compost application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of stiff-stemmed grass hedges can be a valuable soil conservation measure. A study was conducted to measure the effectiveness of a narrow grass hedge, planted on the contour along the hillslope, in reducing runoff nutrient transport from plots with a range of soil nutrient values. Composted ...

  16. Nutrient Requirements in Adolescence.

    ERIC Educational Resources Information Center

    McKigney, John I,; Munro, Hamish N.

    It is important to understand the nutrient requirements and the significance of nutrition both in pubescence and adolescence. The pubescent growth spurt is characterized by an increase in body size and a change in proportion of different tissues. Both of these factors are of great nutritional importance, since there is reason to believe that the…

  17. Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment

    NASA Astrophysics Data System (ADS)

    Armitage, A. R.; Fourqurean, J. W.

    2015-10-01

    The carbon sequestration potential in coastal soils is linked to aboveground and belowground plant productivity and biomass, which in turn, is directly and indirectly influenced by nutrient input. We evaluated the influence of long-term and near-term nutrient input on aboveground and belowground carbon accumulation in seagrass beds, using a nutrient enrichment (nitrogen and phosphorus) experiment embedded within a naturally occurring, long-term gradient of phosphorus availability within Florida Bay (USA). We measured organic carbon stocks in soils and above- and belowground seagrass biomass after 17 months of experimental nutrient addition. At the nutrient-limited sites, phosphorus addition increased the carbon stock in aboveground seagrass biomass by more than 300 %; belowground seagrass carbon stock increased by 50-100 %. Soil carbon content slightly decreased (~ 10 %) in response to phosphorus addition. There was a strong but non-linear relationship between soil carbon and Thalassia testudinum leaf nitrogen: phosphorus (N : P) or belowground seagrass carbon stock. When seagrass leaf N : P exceeded a threshold of 75 : 1, or when belowground seagrass carbon stock was less than 100 g m-2, there was less than 3 % organic carbon in the sediment. Despite the marked difference in soil carbon between phosphorus-limited and phosphorus-replete areas of Florida Bay, all areas of the bay had relatively high soil carbon stocks near or above the global median of 1.8 % organic carbon. The relatively high carbon content in the soils indicates that seagrass beds have extremely high carbon storage potential, even in nutrient-limited areas with low biomass or productivity.

  18. Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment

    NASA Astrophysics Data System (ADS)

    Armitage, A. R.; Fourqurean, J. W.

    2016-01-01

    The carbon sequestration potential in coastal soils is linked to aboveground and belowground plant productivity and biomass, which in turn, is directly and indirectly influenced by nutrient input. We evaluated the influence of long-term and near-term nutrient input on aboveground and belowground carbon accumulation in seagrass beds, using a nutrient enrichment (nitrogen and phosphorus) experiment embedded within a naturally occurring, long-term gradient of phosphorus availability within Florida Bay (USA). We measured organic carbon stocks in soils and above- and belowground seagrass biomass after 17 months of experimental nutrient addition. At the nutrient-limited sites, phosphorus addition increased the carbon stock in aboveground seagrass biomass by more than 300 %; belowground seagrass carbon stock increased by 50-100 %. Soil carbon content slightly decreased ( ˜ 10 %) in response to phosphorus addition. There was a strong but non-linear relationship between soil carbon and Thalassia testudinum leaf nitrogen : phosphorus (N : P) or belowground seagrass carbon stock. When seagrass leaf N : P exceeded an approximate threshold of 75 : 1, or when belowground seagrass carbon stock was less than 100 g m-2, there was less than 3 % organic carbon in the sediment. Despite the marked difference in soil carbon between phosphorus-limited and phosphorus-replete areas of Florida Bay, all areas of the bay had relatively high soil carbon stocks near or above the global median of 1.8 % organic carbon. The relatively high carbon content in the soils indicates that seagrass beds have extremely high carbon storage potential, even in nutrient-limited areas with low biomass or productivity.

  19. Overexpression of a NAC transcription factor delays leaf senescence and increases grain nitrogen concentration in wheat.

    PubMed

    Zhao, D; Derkx, A P; Liu, D-C; Buchner, P; Hawkesford, M J

    2015-07-01

    Increasing the duration of leaf photosynthesis during grain filling using slow-senescing functional stay-green phenotypes is a possible route for increasing grain yields in wheat (Triticum aestivum L.). However, delayed senescence may negatively affect nutrient remobilisation and hence reduce grain protein concentrations and grain quality. A novel NAC1-type transcription factor (hereafter TaNAC-S) was identified in wheat, with gene expression located primarily in leaf/sheath tissues, which decreased during post-anthesis leaf senescence. Expression of TaNAC-S in the second leaf correlated with delayed senescence in two doubled-haploid lines of an Avalon × Cadenza population (lines 112 and 181), which were distinct for leaf senescence. Transgenic wheat plants overexpressing TaNAC-S resulted in delayed leaf senescence (stay-green phenotype). Grain yield, aboveground biomass, harvest index and total grain N content were unaffected, but NAC over-expressing lines had higher grain N concentrations at similar grain yields compared to non-transgenic controls. These results indicate that TaNAC-S is a negative regulator of leaf senescence, and that delayed leaf senescence may lead not only to increased grain yields but also to increased grain protein concentrations.

  20. Preferential feeding by an aquatic consumer mediates non-additive decomposition of speciose leaf litter.

    PubMed

    Swan, Christopher M; Palmer, Margaret A

    2006-08-01

    Forest soils and streams receive substantial inputs of detritus from deciduous vegetation. Decay of this material is a critical ecosystem process, recycling nutrients and supporting detrital-based food webs, and has been attributed, in part, to leaf litter species composition. However, research on why speciose leaf litter should degrade differently has relied on a bottom-up approach, embracing interspecific variation in litter chemistry. We hypothesized that preferential feeding by an aquatic detritivore interacts with species-specific leaf palatability and slows decay of speciose leaf litter. We addressed this by offering four single- and mixed-species leaf resources to field densities of a leaf-shredding consumer. Mixing leaf species resulted in slower total leaf decomposition. Decreases in mixed-species decomposition was partly explained by preferential feeding by the consumers in one case, but the lack of preferential feeding in other mixtures suggested an interactive effect of feeding and microbial degradation. Loss of riparian tree biodiversity may have implications for in-stream consumer-resource interactions.

  1. Leaf Length Tracker: a novel approach to analyse leaf elongation close to the thermal limit of growth in the field

    PubMed Central

    Kirchgessner, Norbert; Yates, Steven; Hiltpold, Maya; Walter, Achim

    2016-01-01

    Leaf growth in monocot crops such as wheat and barley largely follows the daily temperature course, particularly under cold but humid springtime field conditions. Knowledge of the temperature response of leaf extension, particularly variations close to the thermal limit of growth, helps define physiological growth constraints and breeding-related genotypic differences among cultivars. Here, we present a novel method, called ‘Leaf Length Tracker’ (LLT), suitable for measuring leaf elongation rates (LERs) of cereals and other grasses with high precision and high temporal resolution under field conditions. The method is based on image sequence analysis, using a marker tracking approach to calculate LERs. We applied the LLT to several varieties of winter wheat (Triticum aestivum), summer barley (Hordeum vulgare), and ryegrass (Lolium perenne), grown in the field and in growth cabinets under controlled conditions. LLT is easy to use and we demonstrate its reliability and precision under changing weather conditions that include temperature, wind, and rain. We found that leaf growth stopped at a base temperature of 0°C for all studied species and we detected significant genotype-specific differences in LER with rising temperature. The data obtained were statistically robust and were reproducible in the tested environments. Using LLT, we were able to detect subtle differences (sub-millimeter) in leaf growth patterns. This method will allow the collection of leaf growth data in a wide range of future field experiments on different graminoid species or varieties under varying environmental or treatment conditions. PMID:26818912

  2. Does investment in leaf defenses drive changes in leaf economic strategy? A focus on whole-plant ontogeny.

    PubMed

    Mason, Chase M; Donovan, Lisa A

    2015-04-01

    Leaf defenses have long been studied in the context of plant growth rate, resource availability, and optimal investment theory. Likewise, one of the central modern paradigms of plant ecophysiology, the leaf economics spectrum (LES), has been extensively studied in the context of these factors across ecological scales ranging from global species data sets to temporal shifts within individuals. Despite strong physiological links between LES strategy and leaf defenses in structure, function, and resource investment, the relationship between these trait classes has not been well explored. This study investigates the relationship between leaf defenses and LES strategy across whole-plant ontogeny in three diverse Helianthus species known to exhibit dramatic ontogenetic shifts in LES strategy, focusing primarily on physical and quantitative chemical defenses. Plants were grown under controlled environmental conditions and sampled for LES and defense traits at four ontogenetic stages. Defenses were found to shift strongly with ontogeny, and to correlate strongly with LES strategy. More advanced ontogenetic stages with more conservative LES strategy leaves had higher tannin activity and toughness in all species, and higher leaf dry matter content in two of three species. Modeling results in two species support the conclusion that changes in defenses drive changes in LES strategy through ontogeny, and in one species that changes in defenses and LES strategy are likely independently driven by ontogeny. Results of this study support the hypothesis that leaf-level allocation to defenses might be an important determinant of leaf economic traits, where high investment in defenses drives a conservative LES strategy.

  3. The oxygen isotope enrichment of leaf-exported assimilates--does it always reflect lamina leaf water enrichment?

    PubMed

    Gessler, Arthur; Brandes, Elke; Keitel, Claudia; Boda, Sonja; Kayler, Zachary E; Granier, André; Barbour, Margaret; Farquhar, Graham D; Treydte, Kerstin

    2013-10-01

    The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant-climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected (18)O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem (18)O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data.

  4. The oxygen isotope enrichment of leaf-exported assimilates – does it always reflect lamina leaf water enrichment?

    PubMed Central

    Gessler, Arthur; Brandes, Elke; Keitel, Claudia; Boda, Sonja; Kayler, Zachary E; Granier, André; Barbour, Margaret; Farquhar, Graham D; Treydte, Kerstin

    2013-01-01

    The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant–climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected 18O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem 18O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data. PMID:23763637

  5. Estimation of stream nutrient uptake from nutrient addition experiments

    SciTech Connect

    Payn, Robert

    2005-09-01

    Nutrient uptake in streams is often quantified by determining nutrient uptake length. However, current methods for measuring nutrient uptake length are often impractical, expensive, or demonstrably incorrect. We have developed a new method to estimate ambient nutrient uptake lengths using field experiments involving several levels of nutrient addition. Data analysis involves plotting nutrient addition uptake lengths versus added concentration and extrapolating to the negative ambient concentration. This method is relatively easy, inexpensive, and based on sound theoretical development. It is more accurate than the commonly used method involving a single nutrient addition. The utility of the method is supported by field studies directly comparing our new method with isotopic tracer methods for determining uptake lengths of phosphorus, ammonium, and nitrate. Our method also provides parameters for comparing potential nutrient limitation among streams.

  6. Facilitation promotes changes in leaf economics traits of a perennial forb.

    PubMed

    García-Cervigón, Ana I; Linares, Juan Carlos; Aibar, Pablo; Olano, José M

    2015-09-01

    Optimal allocation of resources is crucial to maximize plant success. Plants modify their economic strategies by adjusting functional traits in response to shifts in environmental conditions. Facilitation has been recognized as a major biotic filter of trait distribution in communities, although the effect of facilitation on intraspecific variability has been scarcely explored. We evaluated intraspecific shifts in leaf functional traits of a perennial forb (Helleborus foetidus) in relation to the presence of a nurse plant (Juniperus sabina) in two sites with contrasting abiotic stress levels. The effects of abiotic (site) and biotic (juniper presence, microsite) environments on specific leaf area (SLA), leaf area (LA), lamina/petiole length ratio (LPR), intrinsic water use efficiency (iWUE) and leaf nutrient content (N, P and N:P) per mass were evaluated. Alleviation of drought stress associated with nurse plant presence was reflected in SLA, LA, LPR and iWUE at the high-stress site. Individuals growing in open areas showed more resource-conservative traits, supporting the argument that this strategy is advantageous in environments that limit opportunities for rapid carbon gain. Leaf nutrients were unrelated to other traits. The large amount of intraspecific variation in leaf functional traits related to facilitative processes highlights the importance of facilitation as a major source of plant trait variation. Both positive and negative biotic interactions, as well as intraspecific trait variability, should be considered in mechanistic models of plant communities' functional responses to environmental changes.

  7. Plasticity in sunflower leaf and cell growth under high salinity.

    PubMed

    Céccoli, G; Bustos, D; Ortega, L I; Senn, M E; Vegetti, A; Taleisnik, E

    2015-01-01

    A group of sunflower lines that exhibit a range of leaf Na(+) concentrations under high salinity was used to explore whether the responses to the osmotic and ionic components of salinity can be distinguished in leaf expansion kinetics analysis. It was expected that at the initial stages of the salt treatment, leaf expansion kinetics changes would be dominated by responses to the osmotic component of salinity, and that later on, ion inclusion would impose further kinetics changes. It was also expected that differential leaf Na(+) accumulation would be reflected in specific changes in cell division and expansion rates. Plants of four sunflower lines were gradually treated with a relatively high (130 mm NaCl) salt treatment. Leaf expansion kinetics curves were compared in leaves that were formed before, during and after the initiation of the salt treatment. Leaf areas were smaller in salt-treated plants, but the analysis of growth curves did not reveal differences that could be attributed to differential Na(+) accumulation, since similar changes in leaf expansion kinetics were observed in lines with different magnitudes of salt accumulation. Nevertheless, in a high leaf Na(+) -including line, cell divisions were affected earlier, resulting in leaves with proportionally fewer cells than in a Na(+) -excluding line. A distinct change in leaf epidermal pavement shape caused by salinity is reported for the first time. Mature pavement cells in leaves of control plants exhibited typical lobed, jigsaw-puzzle shape, whereas in treated plants, they tended to retain closer-to-circular shapes and a lower number of lobes. PMID:24942979

  8. Harmonization of nutrient intake values.

    PubMed

    King, Janet C; Garza, Cutberto

    2007-03-01

    The conceptual framework for the various NIVs is depicted in figure 1 along with the methodological approaches and applications. The NIVs consist of two values derived from a statistical evaluation of data on nutrient requirements, the average nutrient requirement (ANR), or nutrient toxicities, the upper nutrient level (UNL). The individual nutrient levelx (INLx) is derived from the distribution of average nutrient requirements. The percentile chosen is often 98%, which is equivalent to 2 SD above the mean requirement. Concepts underlying the NIVs include criteria for establishing a nutrient requirement, e.g., ferritin stores, nitrogen balance, or serum vitamin C. Once the requirement for the absorbed nutrient is determined, it may be necessary to adjust the value for food sources, i.e., bioavailability, or host factors, such as the effect of infection on nutrient utilization. Other concepts that committees may want to consider when establishing NIVs include the effects of genetic variation on nutrient requirements and the role of the nutrient in preventing long-term disease. Two fundamental uses of NIVs are for assessing the adequacy of nutrient intakes and for planning diets for individuals and populations. Establishing the NIV using the statistical framework proposed in this report improves the efficacy of the values for identifying risks of nutrient deficiency or excess among individuals and populations. NIVs also are applied to a number of aspects of food and nutrition policy. Some examples include regulatory issues and trade, labeling, planning programs for alleviating public health nutrition problems, food fortification, and dietary guidance.

  9. [Relationships among leaf traits and their expression in different vegetation zones in Yanhe River basin, Northwest China].

    PubMed

    Guo, Ru; Wen, Zhong-ming; Wang, Hong-xia; Qi, De-hui

    2015-12-01

    This article selected zonal plant communities as the research objects in different vegetation zones in Yanhe River basin. We measured six leaf traits of the dominant species and main accompanying species in each community, and then analyzed the relationships and their changes along with environmental gradients between these traits in order to understand the plant adaptation strategies to the environment changes. The results showed that the specific leaf area was significantly negatively correlated to leaf tissue density, area-based leaf nitrogen and phosphorus concentrations, and significantly positively correlated to mass-based leaf phosphorus concentration. Both the scaling relationships among these traits and plant life strategies were different among the three vegetation zones, the scaling-dependent relationship between leaf tissue density and specific leaf area was stronger in steppe and forest-steppe zones than in forest zone, but the correlations among area-based leaf nitrogen/phosphorus concentrations and specific leaf area and leaf tissue density were more significant in forest zone than in steppe zone. In the arid grassland and forest-steppe zone, plants give priority to defensive and stress resistance strategies, and in relatively moist nutrient-rich forest zone, plants give priority to fast growth and resource optimization allocation strategies. PMID:27111998

  10. Intra- and inter-community variation in leaf water repellency along a 4000 m elevation transect in the Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Goldsmith, G. R.; Doughty, C.; Bentley, L. P.; Shenkin, A.; Castro-Ccoscco, R. M.; Salinas, N.; Malhi, Y.

    2014-12-01

    Leaf water repellency is a measure of the hydrophobicity, or wettability, of leaf surfaces. At the scale of the plant, leaf water repellency can affect gas exchange, nutrient exchange, and pathogen growth. At the scale of the ecosystem, it can affect canopy water storage, throughfall, and evaporation. To date, very few studies have measured intra- and inter- community variation in leaf water repellency of tropical forest ecosystems. In the context of a broad survey of plant functional traits, we measured leaf water repellency in nine forest plots occurring across a 4000 m elevation gradient in the eastern Andes of Peru. Observed angles of incidence (63 ± 13°) indicate high leaf wettability, with no significant difference between sun and shade leaves. In contrast with previous research along elevation gradients, we find no strong evidence for variation across sites, but rather find high variation within a given site. Finally, we find that leaf water repellency may be predicted using sunlit leaf spectra with a low RMSE (<25% of the mean), indicating that future research on leaf water repellency could be carried out using high resolution hyperspectral remote sensing. As the climate of tropical ecosystems changes, the resultant changes in leaf water repellency will impact plants, communities and ecosystems. Our results inform our understanding of where and to what extent these impacts are most likely to occur.

  11. Quantitative Nutrient Limitation Analysis of Global Forests by Remote Sensing

    NASA Astrophysics Data System (ADS)

    Lopez, A. M.; Badgley, G. M.; Field, C. B.

    2015-12-01

    Nutrient availability in terrestrial ecosystems may be the primary determinant of the long-term carbon storage capacity of vegetation. Both nutrient availability and carbon storage capacity are highly uncertain and limit our ability to predict atmospheric CO2 concentrations. Terrestrial vegetation, especially forests, play a critical role in regulating the global carbon cycle and Earth's climate by sequestering carbon from the atmosphere. The broad relationship between nutrient availability and increased biomass production can be captured using remotely-sensed spectral information. We develop an approach to estimate total nutrient availability in 848 global forest sites at 1-km spatial resolution by combining the ecological principle of functional convergence with MODIS gross primary productivity (GPP) and evapotranspiration (ET) products from 2000-2013. Convergence in the relationship between maximum GPP and ET of nutrient-rich forests indicate that any sites deviating from this upper-limit are associated with a lower availability of nutrients. This method offers a way to examine the severity, as well as the spatial extent of nutrient limitation at the global scale. We find that the degree to which forests are nutrient limited range between 0% and 81% with an average limitation of 16 ± 17%. Our method agrees with regional nutrient gradients (i.e. SW-NE Amazon), but does not tightly correspond with recently published nutrient limitation classification standards (Fernandez-Martinez et al., 2014). A global terrestrial nutrient limitation map can assist in diagnosing the health of vegetation while removing the necessity for extensive field sampling or local nutrient addition experiments. Further research will expand the study sites to obtain a complete global terrestrial nutrient limitation map.

  12. Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees.

    PubMed

    Chen, Weile; Koide, Roger T; Adams, Thomas S; DeForest, Jared L; Cheng, Lei; Eissenstat, David M

    2016-08-01

    Photosynthesis by leaves and acquisition of water and minerals by roots are required for plant growth, which is a key component of many ecosystem functions. Although the role of leaf functional traits in photosynthesis is generally well understood, the relationship of root functional traits to nutrient uptake is not. In particular, predictions of nutrient acquisition strategies from specific root traits are often vague. Roots of nearly all plants cooperate with mycorrhizal fungi in nutrient acquisition. Most tree species form symbioses with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi. Nutrients are distributed heterogeneously in the soil, and nutrient-rich "hotspots" can be a key source for plants. Thus, predicting the foraging strategies that enable mycorrhizal root systems to exploit these hotspots can be critical to the understanding of plant nutrition and ecosystem carbon and nutrient cycling. Here, we show that in 13 sympatric temperate tree species, when nutrient availability is patchy, thinner root species alter their foraging to exploit patches, whereas thicker root species do not. Moreover, there appear to be two distinct pathways by which thinner root tree species enhance foraging in nutrient-rich patches: AM trees produce more roots, whereas EM trees produce more mycorrhizal fungal hyphae. Our results indicate that strategies of nutrient foraging are complementary among tree species with contrasting mycorrhiza types and root morphologies, and that predictable relationships between below-ground traits and nutrient acquisition emerge only when both roots and mycorrhizal fungi are considered together. PMID:27432986

  13. Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees.

    PubMed

    Chen, Weile; Koide, Roger T; Adams, Thomas S; DeForest, Jared L; Cheng, Lei; Eissenstat, David M

    2016-08-01

    Photosynthesis by leaves and acquisition of water and minerals by roots are required for plant growth, which is a key component of many ecosystem functions. Although the role of leaf functional traits in photosynthesis is generally well understood, the relationship of root functional traits to nutrient uptake is not. In particular, predictions of nutrient acquisition strategies from specific root traits are often vague. Roots of nearly all plants cooperate with mycorrhizal fungi in nutrient acquisition. Most tree species form symbioses with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi. Nutrients are distributed heterogeneously in the soil, and nutrient-rich "hotspots" can be a key source for plants. Thus, predicting the foraging strategies that enable mycorrhizal root systems to exploit these hotspots can be critical to the understanding of plant nutrition and ecosystem carbon and nutrient cycling. Here, we show that in 13 sympatric temperate tree species, when nutrient availability is patchy, thinner root species alter their foraging to exploit patches, whereas thicker root species do not. Moreover, there appear to be two distinct pathways by which thinner root tree species enhance foraging in nutrient-rich patches: AM trees produce more roots, whereas EM trees produce more mycorrhizal fungal hyphae. Our results indicate that strategies of nutrient foraging are complementary among tree species with contrasting mycorrhiza types and root morphologies, and that predictable relationships between below-ground traits and nutrient acquisition emerge only when both roots and mycorrhizal fungi are considered together.

  14. Leaf venation: structure, function, development, evolution, ecology and applications in the past, present and future.

    PubMed

    Sack, Lawren; Scoffoni, Christine

    2013-06-01

    The design and function of leaf venation are important to plant performance, with key implications for the distribution and productivity of ecosystems, and applications in paleobiology, agriculture and technology. We synthesize classical concepts and the recent literature on a wide range of aspects of leaf venation. We describe 10 major structural features that contribute to multiple key functions, and scale up to leaf and plant performance. We describe the development and plasticity of leaf venation and its adaptation across environments globally, and a new global data compilation indicating trends relating vein length per unit area to climate, growth form and habitat worldwide. We synthesize the evolution of vein traits in the major plant lineages throughout paleohistory, highlighting the multiple origins of individual traits. We summarize the strikingly diverse current applications of leaf vein research in multiple fields of science and industry. A unified core understanding will enable an increasing range of plant biologists to incorporate leaf venation into their research.

  15. Responses of primary production, leaf litter decomposition and associated communities to stream eutrophication.

    PubMed

    Dunck, Bárbara; Lima-Fernandes, Eva; Cássio, Fernanda; Cunha, Ana; Rodrigues, Liliana; Pascoal, Cláudia

    2015-07-01

    We assessed the eutrophication effects on leaf litter decomposition and primary production, and on periphytic algae, fungi and invertebrates. According to the subsidy-stress model, we expected that when algae and decomposers were nutrient limited, their activity and diversity would increase at moderate levels of nutrient enrichment, but decrease at high levels of nutrients, because eutrophication would lead to the presence of other stressors and overwhelm the subsidy effect. Chestnut leaves (Castanea sativa Mill) were enclosed in mesh bags and immersed in five streams of the Ave River basin (northwest Portugal) to assess leaf decomposition and colonization by invertebrates and fungi. In parallel, polyethylene slides were attached to the mesh bags to allow colonization by algae and to assess primary production. Communities of periphytic algae and decomposers discriminated the streams according to the trophic state. Primary production decomposition and biodiversity were lower in streams at both ends of the trophic gradient.

  16. Responses of primary production, leaf litter decomposition and associated communities to stream eutrophication.

    PubMed

    Dunck, Bárbara; Lima-Fernandes, Eva; Cássio, Fernanda; Cunha, Ana; Rodrigues, Liliana; Pascoal, Cláudia

    2015-07-01

    We assessed the eutrophication effects on leaf litter decomposition and primary production, and on periphytic algae, fungi and invertebrates. According to the subsidy-stress model, we expected that when algae and decomposers were nutrient limited, their activity and diversity would increase at moderate levels of nutrient enrichment, but decrease at high levels of nutrients, because eutrophication would lead to the presence of other stressors and overwhelm the subsidy effect. Chestnut leaves (Castanea sativa Mill) were enclosed in mesh bags and immersed in five streams of the Ave River basin (northwest Portugal) to assess leaf decomposition and colonization by invertebrates and fungi. In parallel, polyethylene slides were attached to the mesh bags to allow colonization by algae and to assess primary production. Communities of periphytic algae and decomposers discriminated the streams according to the trophic state. Primary production decomposition and biodiversity were lower in streams at both ends of the trophic gradient. PMID:25797823

  17. Molecular Mechanisms of Phosphorus Metabolism and Transport during Leaf Senescence

    PubMed Central

    Stigter, Kyla A.; Plaxton, William C.

    2015-01-01

    Leaf senescence, being the final developmental stage of the leaf, signifies the transition from a mature, photosynthetically active organ to the attenuation of said function and eventual death of the leaf. During senescence, essential nutrients sequestered in the leaf, such as phosphorus (P), are mobilized and transported to sink tissues, particularly expanding leaves and developing seeds. Phosphorus recycling is crucial, as it helps to ensure that previously acquired P is not lost to the environment, particularly under the naturally occurring condition where most unfertilized soils contain low levels of soluble orthophosphate (Pi), the only form of P that roots can directly assimilate from the soil. Piecing together the molecular mechanisms that underpin the highly variable efficiencies of P remobilization from senescing leaves by different plant species may be critical for devising effective strategies for improving overall crop P-use efficiency. Maximizing Pi remobilization from senescing leaves using selective breeding and/or biotechnological strategies will help to generate P-efficient crops that would minimize the use of unsustainable and polluting Pi-containing fertilizers in agriculture. This review focuses on the molecular mechanisms whereby P is remobilized from senescing leaves and transported to sink tissues, which encompasses the action of hormones, transcription factors, Pi-scavenging enzymes, and Pi transporters. PMID:27135351

  18. Nutrient status of the lowbush blueberry, Lac-Saint-Jean area, Quebec, Canada. [Vaccinium angustifolium

    SciTech Connect

    Bouchard, A.R.; Gagnon, M.J.

    1987-01-01

    The lowbush blueberry (Vaccinium angustifolium Ait.) is an important commercial crop of the Lac-Saint-Jean area (Quebec, Canada). The major blueberry fields are located on sandy soils relatively poor in available mineral nutrients. The nutrients originate from a thin organic layer found on the top of these sandy soils. The leaf mineral contents (N, P, K, Mg, Ca, Mn, Fe, Cu, Zn and B) were measured in five blueberry fields during 1984 and 1985. Soil pH and soil available P, K, and Mg were also assessed. The results show that the leaf mineral contents are generally adequate. However, K and Zn might be occasionally deficient when compared to the actual established standards. The available Mg in soil was significantly correlated with the leaf Mg concentration. The data also suggest that the influence of the pH following the burn pruning seems to influence the nutrition of this species.

  19. Nutrients in the nexus

    USGS Publications Warehouse

    Davidson, Eric A.; Niphong, Rachel; Ferguson, Richard B.; Palm, Cheryl; Osmond, Deanna L.; Baron, Jill S.

    2016-01-01

    Synthetic nitrogen (N) fertilizer has enabled modern agriculture to greatly improve human nutrition during the twentieth century, but it has also created unintended human health and environmental pollution challenges for the twenty-first century. Averaged globally, about half of the fertilizer-N applied to farms is removed with the crops, while the other half remains in the soil or is lost from farmers’ fields, resulting in water and air pollution. As human population continues to grow and food security improves in the developing world, the dual development goals of producing more nutritious food with low pollution will require both technological and socio-economic innovations in agriculture. Two case studies presented here, one in sub-Saharan Africa and the other in Midwestern United States, demonstrate how management of nutrients, water, and energy is inextricably linked in both small-scale and large-scale food production, and that science-based solutions to improve the efficiency of nutrient use can optimize food production while minimizing pollution. To achieve the needed large increases in nutrient use efficiency, however, technological developments must be accompanied by policies that recognize the complex economic and social factors affecting farmer decision-making and national policy priorities. Farmers need access to affordable nutrient supplies and support information, and the costs of improving efficiencies and avoiding pollution may need to be shared by society through innovative policies. Success will require interdisciplinary partnerships across public and private sectors, including farmers, private sector crop advisors, commodity supply chains, government agencies, university research and extension, and consumers.

  20. Hydrologic and biologic influences on stream network nutrient concentrations: Interactions of hydrologic turnover and concentration-dependent nutrient uptake

    NASA Astrophysics Data System (ADS)

    Mallard, John; McGlynn, Brian; Covino, Tim

    2016-04-01

    Stream networks lie in a crucial landscape position between terrestrial ecosystems and downstream water bodies. As such, whether inferring terrestrial watershed processes from watershed outlet nutrient signals or predicting the effect of observed terrestrial processes on stream nutrient signals, it is requisite to understand how stream networks can modulate terrestrial nutrient inputs. To date integrated understanding and modeling of physical and biological influences on nutrient concentrations at the stream network scale have been limited. However, watershed scale groundwater - surface water exchange (hydrologic turnover), concentration-variable biological uptake, and the interaction between the two can strongly modify stream water nutrient concentrations. Stream water and associated nutrients are lost to and replaced from groundwater with distinct nutrient concentrations while in-stream nutrients can also be retained by biological processes at rates that vary with concentration. We developed an empirically based network scale model to simulate the interaction between hydrologic turnover and concentration-dependent nutrient uptake across stream networks. Exchange and uptake parameters were measured using conservative and nutrient tracer addition experiments in the Bull Trout Watershed, central Idaho. We found that the interaction of hydrologic turnover and concentration-dependent uptake combined to modify and subsequently stabilize in-stream concentrations, with specific concentrations dependent on the magnitude of hydrologic turnover, groundwater concentrations, and the shape of nutrient uptake kinetic curves. We additionally found that by varying these physical and biological parameters within measured ranges we were able to generate a spectrum of stream network concentration distributions representing a continuum of shifting magnitudes of physical and biological influences on in-stream concentrations. These findings elucidate the important and variable role of

  1. Biochemistry of Indian summer: physiology of autumnal leaf coloration.

    PubMed

    Matile, P

    2000-03-01

    The autumnal coloration of foliage in deciduous trees represents a most spectacular phytogerontological phenomenon. It is primarily due to the progressive loss of chlorophyll coinciding with the partial retention of carotenoids. Leaf senescence is a developmental process that is aimed at the recycling of nutrients to perennial parts of the tree for reuse upon the production of new foliage in spring. The remobilization of protein in senescing chloroplasts requires the dismantling of pigment-protein complexes and concomitant photodynamic inactivation of chlorophyll. Detoxification of chlorophyll is achieved by enzymic opening of the porphyrin macrocycle followed by modifications of the resulting linear tetrapyrrole and storage of colorless final catabolites in the vacuoles of degreening leaf cells. The polychromatic beauty of autumnal trees is due to species-specific variations of the degree of carotenoid retention, new synthesis of red anthocyanins and, upon cell death, the formation of dark oxidation products of phenolics. PMID:10767575

  2. Bone nutrients for vegetarians.

    PubMed

    Mangels, Ann Reed

    2014-07-01

    The process of bone mineralization and resorption is complex and is affected by numerous factors, including dietary constituents. Although some dietary factors involved in bone health, such as calcium and vitamin D, are typically associated with dairy products, plant-based sources of these nutrients also supply other key nutrients involved in bone maintenance. Some research suggests that vegetarian diets, especially vegan diets, are associated with lower bone mineral density (BMD), but this does not appear to be clinically significant. Vegan diets are not associated with an increased fracture risk if calcium intake is adequate. Dietary factors in plant-based diets that support the development and maintenance of bone mass include calcium, vitamin D, protein, potassium, and soy isoflavones. Other factors present in plant-based diets such as oxalic acid and phytic acid can potentially interfere with absorption and retention of calcium and thereby have a negative effect on BMD. Impaired vitamin B-12 status also negatively affects BMD. The role of protein in calcium balance is multifaceted. Overall, calcium and protein intakes in accord with Dietary Reference Intakes are recommended for vegetarians, including vegans. Fortified foods are often helpful in meeting recommendations for calcium and vitamin D. Plant-based diets can provide adequate amounts of key nutrients for bone health. PMID:24898231

  3. Bone nutrients for vegetarians.

    PubMed

    Mangels, Ann Reed

    2014-07-01

    The process of bone mineralization and resorption is complex and is affected by numerous factors, including dietary constituents. Although some dietary factors involved in bone health, such as calcium and vitamin D, are typically associated with dairy products, plant-based sources of these nutrients also supply other key nutrients involved in bone maintenance. Some research suggests that vegetarian diets, especially vegan diets, are associated with lower bone mineral density (BMD), but this does not appear to be clinically significant. Vegan diets are not associated with an increased fracture risk if calcium intake is adequate. Dietary factors in plant-based diets that support the development and maintenance of bone mass include calcium, vitamin D, protein, potassium, and soy isoflavones. Other factors present in plant-based diets such as oxalic acid and phytic acid can potentially interfere with absorption and retention of calcium and thereby have a negative effect on BMD. Impaired vitamin B-12 status also negatively affects BMD. The role of protein in calcium balance is multifaceted. Overall, calcium and protein intakes in accord with Dietary Reference Intakes are recommended for vegetarians, including vegans. Fortified foods are often helpful in meeting recommendations for calcium and vitamin D. Plant-based diets can provide adequate amounts of key nutrients for bone health.

  4. Effects of sulfur-dioxide and selected nutrient solutions upon western wheatgrass

    SciTech Connect

    Bicak, C.J.

    1982-01-01

    Sulfur dioxide is a key component of emissions from coal burning power plants. The effect of SO/sub 2/ upon dominant vegetation in the northern mixed prairie, an area in which production and burning of coal are expected to expand, is of considerable importance. Western wheatgrass plants (Agropyron smithii Rydb.) were maintained in nutrient solutions and exposed to different atmoshperic concentrations of SO/sub 2/ and root medium concentrations of sulfate (SO/sub 4/=) in field experiments. Plants were analyzed at three levels of organization: segments of leaf blades, fully expanded leaf blades and tillers. There were substantial gradients of increasing sulfur concentration from the bases to the tips of individual leaf blades. There was also a general increase in sulfur concentration from the youngest to the oldest leaf blade. Differences in sulfur concentration of leaf blade segments and leaf blades were not strongly related to SO/sub 2/ and demonstrates recognizable yet variable patterns of sulfur distribution. The objective of the laboratory experiment was to determine the effect of sulfur nutrition on growth of western wheatgrass. Growth was only minimally affected by three nutrient solution concentrations of SO/sub 4/ = (0 mM, 2 mM, and 4mM). It was concluded that the burning of coal and the maintenance of quality grassland dominated by western wheatgrass are compatible.

  5. National Nutrient Database for Standard Reference - Find Nutrient Value of Common Foods by Nutrient

    MedlinePlus

    ... Department of Agriculture Agricultural Research Service National Nutrient Database for Standard Reference Release 28 NDL Home Food ... Sort by: Measure by: * required field ​ National Nutrient Database for Standard Reference Release 28 slightly revised May, ...

  6. Temporal disparity in leaf chlorophyll content and leaf area index across a growing season in a temperate deciduous forest

    NASA Astrophysics Data System (ADS)

    Croft, H.; Chen, J. M.; Zhang, Y.

    2014-12-01

    Spatial and temporal variations in canopy structure and leaf biochemistry have considerable influence on fluxes of CO2, water and energy and nutrient cycling in vegetation. Two vegetation indices (VI), NDVI and Macc01, were used to model the spatio-temporal variability of broadleaf chlorophyll content and leaf area index (LAI) across a growing season. Ground data including LAI, hyperspectral leaf reflectance factors (400-2500 nm) and leaf chlorophyll content were measured across the growing season and satellite-derived canopy reflectance data was acquired for 33 dates at 1200 m spatial resolution. Key phenological information was extracted using the TIMESAT software. Results showed that LAI and chlorophyll start of season (SOS) dates were at day of year (DOY) 130 and 157 respectively, and total season duration varied by 57 days. The spatial variability of chlorophyll and LAI phenology was also analyzed at the landscape scale to investigate phenological patterns over a larger spatial extent. Whilst a degree of spatial variability existed, results showed that chlorophyll SOS lagged approximately 20-35 days behind LAI SOS, and the end of season (EOS) LAI dates were predominantly between 20 and 30 days later than chlorophyll EOS. The large temporal differences between VI-derived chlorophyll content and LAI has important implications for biogeochemical models using NDVI or LAI to represent the fraction of photosynthetically active radiation absorbed by a canopy, in neglecting to account for delays in chlorophyll production and thus photosynthetic capacity.

  7. Leaf Relative Water Content Estimated from Leaf Reflectance and Transmittance

    NASA Technical Reports Server (NTRS)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2016-01-01

    Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.

  8. Regulation of Compound Leaf Development

    PubMed Central

    Wang, Yuan; Chen, Rujin

    2013-01-01

    Leaf morphology is one of the most variable, yet inheritable, traits in the plant kingdom. How plants develop a variety of forms and shapes is a major biological question. Here, we discuss some recent progress in understanding the development of compound or dissected leaves in model species, such as tomato (Solanum lycopersicum), Cardamine hirsuta and Medicago truncatula, with an emphasis on recent discoveries in legumes. We also discuss progress in gene regulations and hormonal actions in compound leaf development. These studies facilitate our understanding of the underlying regulatory mechanisms and put forward a prospective in compound leaf studies. PMID:27135488

  9. Nutrient yield of the Apalachicola River flood plain, Florida; water-quality assessment plan

    USGS Publications Warehouse

    Mattraw, H.C.; Elder, John F.

    1980-01-01

    The Apalachicola River in northwestern Florida is the location of one of four current U.S. Geological Survey National River Quality Assessments. The investigation of the Apalachicola River and flood plain is designed to quantify the organic detritus and nutrient yield to the productive, estuarine Apalachicola Bay. The extensive riverine flood plain is subject to seasonal flooding which transports large quantities of accumulated, decaying leaf litter from the flood plain into the river and ultimately into Apalachicola Bay. The Apalachicola River Quality Assessment has four major objectives; (1) Determine the accumulation of organic substances and trace elements in benthic organisms and fine-grained sediments; (2) Define the distribution of the major tree communities on the flood plain; (3) Assess the role of leaf fall and decomposition on nutrient yield; and (4) Identify and quantify major sources and pathways of nutrients to the river. Extensive emphasis is given to investigation approaches and techniques to facilitate technology transfer to similar wetland ecosystems. (USGS)

  10. Remote sensing of LAI, chlorophyll and leaf nitrogen pools of crop- and grasslands in five European landscapes

    NASA Astrophysics Data System (ADS)

    Boegh, E.; Houborg, R.; Bienkowski, J.; Braban, C. F.; Dalgaard, T.; van Dijk, N.; Dragosits, U.; Holmes, E.; Magliulo, V.; Schelde, K.; Di Tommasi, P.; Vitale, L.; Theobald, M. R.; Cellier, P.; Sutton, M. A.

    2013-10-01

    as the relationships between spectral vegetation indices (SVIs) and field measurements. When the range of surface types increased, the REGFLEC results were in better agreement with field data than the empirical SVI regression models. Selecting only homogeneous canopies with uniform CHLl distributions as reference data for evaluation, REGFLEC was able to explain 69% of LAI observations (rmse = 0.76), 46% of measured canopy chlorophyll contents (rmse = 719 mg m-2) and 51% of measured canopy nitrogen contents (rmse = 2.7 g m-2). Better results were obtained for individual landscapes, except for Italy, where REGFLEC performed poorly due to a lack of dense vegetation canopies at the time of satellite recording. Presence of vegetation is needed to parameterize the REGFLEC model. Combining REGFLEC- and SVI-based model results to minimize errors for a "snap-shot" assessment of total leaf nitrogen pools in the five landscapes, results varied from 0.6 to 4.0 t km-2. Differences in leaf nitrogen pools between landscapes are attributed to seasonal variations, extents of agricultural area, species variations, and spatial variations in nutrient availability. In order to facilitate a substantial assessment of variations in Nl pools and their relation to landscape based nitrogen and carbon cycling processes, time series of satellite data are needed. The upcoming Sentinel-2 satellite mission will provide new multiple narrowband data opportunities at high spatio-temporal resolution which are expected to further improve remote sensing capabilities for mapping LAI, CHLl and Nl.

  11. Nutrient-substituted hydroxyapatites: synthesis and characterization

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.

    1999-01-01

    Incorporation of Mg, S, and plant-essential micronutrients into the structure of synthetic hydroxyapatite (HA) may be advantageous for closed-loop systems, such as will be required on Lunar and Martian outposts, because these apatites can be used as slow-release fertilizers. Our objective was to synthesize HA with Ca, P, Mg, S, Fe, Cu, Mn, Zn, Mo, B, and Cl incorporated into the structure, i.e., nutrient-substituted apatites. Hydroxyapatite, carbonate hydroxyapatite (CHA), nutrient-substituted hydroxyapatite (NHA), and nutrient-substituted carbonate hydroxyapatite (NCHA) were synthesized by precipitating from solution. Chemical and mineralogical analysis of precipitated samples indicated a considerable fraction of the added cations were incorporated into HA, without mineral impurities. Particle size of the HA was in the 1 to 40 nm range, and decreased with increased substitution of nutrient elements. The particle shape of HA was elongated in the c-direction in unsubstituted HA and NHA but more spherical in CHA and NCHA. The substitution of cations and anions in the HA structure was confirmed by the decrease of the d[002] spacing of HA with substitution of ions with an ionic radius less than that of Ca or P. The DTPA-extractable Cu ranged from 8 to 8429 mg kg-1, Zn ranged from 57 to 1279 mg kg-1, Fe from 211 to 2573 mg kg-1, and Mn from 190 to 1719 mg kg-1, depending on the substitution level of each element in HA. Nutrient-substituted HA has the potential to be used as a slow-release fertilizer to supply micronutrients, S, and Mg in addition to Ca and P.

  12. Effects of Salinity on Leaf Spectral Reflectance and Biochemical Parameters of Nitrogen Fixing Soybean Plants (Glycine max L.)

    NASA Astrophysics Data System (ADS)

    Krezhova, Dora D.; Kirova, Elisaveta B.; Yanev, Tony K.; Iliev, Ilko Ts.

    2010-01-01

    Measurements of physiology and hyperspectral leaf reflectance were used to detect salinity stress in nitrogen fixing soybean plants. Seedlings were inoculated with suspension of Bradyrhizobium japonicum strain 273. Salinity was performed at the stage of 2nd-4th trifoliate expanded leaves by adding of NaCl in the nutrient solution of Helrigel in concentrations 40 mM and 80 mM. A comparative analysis was performed between the changes in the biochemical parameters - stress markers (phenols, proline, malondialdehyde, thiol groups), chlorophyll a and b, hydrogen peroxide, and leaf spectral reflectance in the spectral range 450-850 nm. The spectral measurements were carried out by an USB2000 spectrometer. The reflectance data of the control and treated plants in the red, green, red-edge and the near infrared ranges of the spectrum were subjected to statistical analysis. Statistically significant differences were found through the Student's t-criterion at the two NaCl concentrations in all of the ranges examined with the exception of the near infrared range at 40 mM NaCl concentration. Similar results were obtained through linear discriminant analysis. The tents of the phenols, malondialdehyde and chlorophyll a and b were found to decrease at both salinity treatments. In the spectral data this effect is manifested by decrease of the reflectance values in the green and red ranges. The contents of proline, hydrogen peroxide and thiol groups rose with the NaCl concentration increase. At 80 mM NaCl concentration the values of these markers showed a considerable increase giving evidence that the soybean plants were stressed in comparison with the control. This finding is in agreement with the results from the spectral reflectance analysis.

  13. Plant response to nutrient availability across variable bedrock geologies

    USGS Publications Warehouse

    Castle, S.C.; Neff, J.C.

    2009-01-01

    We investigated the role of rock-derived mineral nutrient availability on the nutrient dynamics of overlying forest communities (Populus tremuloides and Picea engelmanni-Abies lasiocarpa v. arizonica) across three parent materials (andesite, limestone, and sandstone) in the southern Rocky Mountains of Colorado. Broad geochemical differences were observed between bedrock materials; however, bulk soil chemistries were remarkably similar between the three different sites. In contrast, soil nutrient pools were considerably different, particularly for P, Ca, and Mg concentrations. Despite variations in nutrient stocks and nutrient availability in soils, we observed relatively inflexible foliar concentrations and foliar stoichiometries for both deciduous and coniferous species. Foliar nutrient resorption (P and K) in the deciduous species followed patterns of nutrient content across substrate types, with higher resorption corresponding to lower bedrock concentrations. Work presented here indicates a complex plant response to available soil nutrients, wherein plant nutrient use compensates for variations in supply gradients and results in the maintenance of a narrow range in foliar stoichiometry. ?? 2008 Springer Science+Business Media, LLC.

  14. Evolution of leaf warbler songs (Aves: Phylloscopidae)

    PubMed Central

    Tietze, Dieter Thomas; Martens, Jochen; Fischer, Balduin S; Sun, Yue-Hua; Klussmann-Kolb, Annette; Päckert, Martin

    2015-01-01

    Songs in passerine birds are important for territory defense and mating. Speciation rates in oscine passerines are so high, due to cultural evolution, that this bird lineage makes up half of the extant bird species. Leaf warblers are a speciose Old-World passerine family of limited morphological differentiation, so that songs are even more important for species delimitation. We took 16 sonographic traits from song recordings of 80 leaf warbler taxa and correlated them with 15 potentially explanatory variables, pairwise, and in linear models. Based on a well-resolved molecular phylogeny of the same taxa, all pairwise correlations were corrected for relatedness with phylogenetically independent contrasts and phylogenetic generalized linear models were used. We found a phylogenetic signal for most song traits, but a strong one only for the duration of the longest and of the shortest element, which are presumably inherited instead of learned. Body size of a leaf warbler species is a constraint on song frequencies independent of phylogeny. At least in this study, habitat density had only marginal impact on song features, which even disappeared through phylogenetic correction. Maybe most leaf warblers avoid the deterioration through sound propagation in dense vegetation by singing from exposed perches. Latitudinal (and longitudinal) extension of the breeding ranges was correlated with most song features, especially verse duration (longer polewards and westwards) and complexity (lower polewards). Climate niche or expansion history might explain these correlations. The number of different element types per verse decreases with elevation, possibly due to fewer resources and congeneric species at higher elevations. PMID:25691998

  15. Headwater Nutrient Concentration Patterns in Response to Storm Events Across Land Use Types using In Situ Sensors

    NASA Astrophysics Data System (ADS)

    Price, A.; Wollheim, W. M.; Mulukutla, G. K.; Carey, R. O.; McDowell, W. H.

    2012-12-01

    Understanding the aquatic biogeochemical impacts of land use change and climate variability will require improved understanding of nutrient variability over temporal scales ranging from storms to seasons. New in situ sensor technology offers the prospect of efficient nutrient measurements over multiple time scales. We quantified nutrient flux patterns in response to storm events across seasons using in situ nutrient sensors deployed in headwater streams draining three land use types (forest, suburban, and agriculture) within the Lamprey River watershed, New Hampshire, between April-December 2012. We utilized two sensor suites, each consisting of a Satlantic Submersible Ultraviolet Nitrate Analyzer (NO3-N), Turner Designs C6 Multi-Sensor Platform (CDOM, Turbidity, Chl), Hydrolab MS5 (Dissolved Oxygen, pH), WET Labs Cycle P (PO4-P), and Hobo Water Level & Conductivity meters. Preliminary spring/summer comparisons at the suburban site suggest increased baseflow nitrate concentrations and decreased diurnal nitrate variability (~0.05 vs. 0.035 mg/L daily fluctuation) following leaf emergence in spring. Nitrate concentrations were diluted during storms. Hysteresis was evident, suggesting groundwater nitrate sources attributable to septic systems were diluted by surface runoff during spring storms. The agricultural stream showed similar but more extreme patterns of increasing baseflow nitrate during the summer (~2.4 to 4.1 mg/L) and dilution during storms. The compilation of a high-frequency dataset for headwater streams across seasons and land-use types will provide valuable insight into complex land use/water quality relationships in urbanizing watersheds.

  16. Relationship of growth parameters and nutrients uptake with canola (Brassica napus L.) yield and yield contribution at different nutrients availability.

    PubMed

    Yasari, Esmaeil; Patwardhan, A M; Ghole, V S; Omid, Ghasemi Chapi; Ahmad, Asgharzadeh

    2008-03-15

    A field experiment was conducted to evaluate the effect of different nutrients on canola (Brassica napus L.) growth parameters, nutrient uptake and ultimately on seed yield. For this purpose a split plot experimental design, with 10 treatments in 4 replications was carried out in 2004-2005, in silt-clay soil at Baiecola Agricultural Research Station, Mazandaran Iran. Canola seed yield, growth parameters (CGR, LAI, RGR and NAR), dry matter accumulation and HI and nutrient content of the leaf were examined. NPK fertilizers together with S and Zn, singly or in combination were applied. The results showed that at treatments T5 (NP), T8 (NPK), T9 (NPKS) and T10 (NPKZn) the higher seed yield (> 2600 kg ha(-1)) coincided with TDM > 880 g m(-2) the peak CGR > or = 13.9 g m(-2) day(-1) and the maximum LAI > or = 4.1. The higher seed yield at T5, T8, T9 and T10 coincided with higher concentrations of nutrients: N, P, K, S and Zn in leaf at flowering having > or = 3.40%, > or = 0.25%, > or = 1.53%, > or = 110 ppm and > or = 22.7 ppm, indicating substantial levels of translocation of nutrients at various stages of plant growth and higher number of pods per plant (> or = 179). Combined application of NPKZn at T10 resulted in maximum seed yield (3090 kg ha(-1)), coinciding with the maximum number of pods per plant (230), maximum TDM (1043 kg ha(-1)), maximum CGR (20.09 g m(-2) day(-1)) and maximum LAI (4.69). PMID:18814645

  17. Siletz River nutrients: Effects of biosolids application

    EPA Science Inventory

    Stream water nutrients were measured in the Siletz River, Oregon, with the goal of comparing dissolved nutrient concentrations, primarily the nitrogenous nutrients nitrate and ammonium, with previously collected data for the Yaquina and Alsea Rivers for the nutrient criteria prog...

  18. Microalgal and cyanobacterial cultivation: the supply of nutrients.

    PubMed

    Markou, Giorgos; Vandamme, Dries; Muylaert, Koenraad

    2014-11-15

    Microalgae and cyanobacteria are a promising new source of biomass that may complement agricultural crops to meet the increasing global demand for food, feed, biofuels and chemical production. Microalgae and cyanobacteria cultivation does not interfere directly with food production, but care should be taken to avoid indirect competition for nutrient (fertilizer) supply. Microalgae and cyanobacteria production requires high concentrations of essential nutrients (C,N,P,S,K,Fe, etc.). In the present paper the application of nutrients and their uptake by microalgae and cyanobacteria is reviewed. The main focus is on the three most significant nutrients, i.e. carbon, nitrogen and phosphorus; however other nutrients are also reviewed. Nutrients are generally taken up in the inorganic form, but several organic forms of them are also assimilable. Some nutrients do not display any inhibition effect on microalgal or cyanobacterial growth, while others, such as NO2 or NH3 have detrimental effects when present in high concentrations. Nutrients in the gaseous form, such as CO2 and NO face a major limitation which is related mainly to their mass transfer from the gaseous to the liquid state. Since the cultivation of microalgae and cyanobacteria consumes considerable quantities of nutrients, strategies to improve the nutrient application efficiency are needed. Additionally, a promising strategy to improve microalgal and cyanobacterial production sustainability is the utilization of waste streams by recycling of waste nutrients. However, major constraints of using waste streams are the reduction of the range of the biomass applications due to production of contaminated biomass and the possible low bio-availability of some nutrients. PMID:25113948

  19. Leaf life span spectrum of tropical woody seedlings: effects of light and ontogeny and consequences for survival

    PubMed Central

    Kitajima, Kaoru; Cordero, Roberto A.; Wright, S. Joseph

    2013-01-01

    Background and Aims Leaf life span is widely recognized as a key life history trait associated with herbivory resistance, but rigorous comparative data are rare for seedlings. The goal of this study was to examine how light environment affects leaf life span, and how ontogenetic development during the first year may influence leaf fracture toughness, lamina density and stem density that are relevant for herbivory resistance, leaf life span and seedling survival. Methods Data from three experiments encompassing 104 neotropical woody species were combined. Leaf life span, lamina and vein fracture toughness, leaf and stem tissue density and seedling survival were quantified for the first-year seedlings at standardized ontogenetic stages in shade houses and common gardens established in gaps and shaded understorey in a moist tropical forest in Panama. Mortality of naturally recruited seedlings till 1 year later was quantified in 800 1-m2 plots from 1994 to 2011. Key Results Median leaf life span ranged widely among species, always greater in shade (ranging from 151 to >1790 d in the understorey and shade houses) than in gaps (115–867 d), but with strong correlation between gaps and shade. Leaf and stem tissue density increased with seedling age, whereas leaf fracture toughness showed only a weak increase. All these traits were positively correlated with leaf life span. Leaf life span and stem density were negatively correlated with seedling mortality in shade, while gap mortality showed no correlation with these traits. Conclusions The wide spectrum of leaf life span and associated functional traits reflects variation in shade tolerance of first-year seedlings among coexisting trees, shrubs and lianas in this neotropical forest. High leaf tissue density is important in enhancing leaf toughness, a known physical defence, and leaf life span. Both seedling leaf life span and stem density should be considered as key functional traits that contribute to seedling survival

  20. Stable isotopes in leaf water of terrestrial plants.

    PubMed

    Cernusak, Lucas A; Barbour, Margaret M; Arndt, Stefan K; Cheesman, Alexander W; English, Nathan B; Feild, Taylor S; Helliker, Brent R; Holloway-Phillips, Meisha M; Holtum, Joseph A M; Kahmen, Ansgar; McInerney, Francesca A; Munksgaard, Niels C; Simonin, Kevin A; Song, Xin; Stuart-Williams, Hilary; West, Jason B; Farquhar, Graham D

    2016-05-01

    Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water.

  1. Carbon/Nitrogen Imbalance Associated with Drought-Induced Leaf Senescence in Sorghum bicolor

    PubMed Central

    Chen, Daoqian; Wang, Shiwen; Xiong, Binglin; Cao, Beibei; Deng, Xiping

    2015-01-01

    Drought stress triggers mature leaf senescence, which supports plant survival and remobilization of nutrients; yet leaf senescence also critically decreases post-drought crop yield. Drought generally results in carbon/nitrogen imbalance, which is reflected in the increased carbon:nitrogen (C:N) ratio in mature leaves, and which has been shown to be involved in inducing leaf senescence under normal growth conditions. Yet the involvement of the carbon/nitrogen balance in regulation of drought-induced leaf senescence is unclear. To investigate the role of carbon/nitrogen balance in drought-induced senescence, sorghum seedlings were subjected to a gradual soil drought treatment. Leaf senescence symptoms and the C:N ratio, which was indicated by the ratio of non-structural carbohydrate to total N content, were monitored during drought progression. In this study, leaf senescence developed about 12 days after the start of drought treatment, as indicated by various senescence symptoms including decreasing photosynthesis, photosystem II photochemistry efficiency (Fv/Fm) and chlorophyll content, and by the differential expression of senescence marker genes. The C:N ratio was significantly enhanced 10 to 12 days into drought treatment. Leaf senescence occurred in the older (lower) leaves, which had higher C:N ratios, but not in the younger (upper) leaves, which had lower C:N ratios. In addition, a detached leaf assay was conducted to investigate the effect of carbon/nitrogen availability on drought-induced senescence. Exogenous application of excess sugar combined with limited nitrogen promoted drought-induced leaf senescence. Thus our results suggest that the carbon/nitrogen balance may be involved in the regulation of drought-induced leaf senescence. PMID:26317421

  2. Carbon/Nitrogen Imbalance Associated with Drought-Induced Leaf Senescence in Sorghum bicolor.

    PubMed

    Chen, Daoqian; Wang, Shiwen; Xiong, Binglin; Cao, Beibei; Deng, Xiping

    2015-01-01

    Drought stress triggers mature leaf senescence, which supports plant survival and remobilization of nutrients; yet leaf senescence also critically decreases post-drought crop yield. Drought generally results in carbon/nitrogen imbalance, which is reflected in the increased carbon:nitrogen (C:N) ratio in mature leaves, and which has been shown to be involved in inducing leaf senescence under normal growth conditions. Yet the involvement of the carbon/nitrogen balance in regulation of drought-induced leaf senescence is unclear. To investigate the role of carbon/nitrogen balance in drought-induced senescence, sorghum seedlings were subjected to a gradual soil drought treatment. Leaf senescence symptoms and the C:N ratio, which was indicated by the ratio of non-structural carbohydrate to total N content, were monitored during drought progression. In this study, leaf senescence developed about 12 days after the start of drought treatment, as indicated by various senescence symptoms including decreasing photosynthesis, photosystem II photochemistry efficiency (Fv/Fm) and chlorophyll content, and by the differential expression of senescence marker genes. The C:N ratio was significantly enhanced 10 to 12 days into drought treatment. Leaf senescence occurred in the older (lower) leaves, which had higher C:N ratios, but not in the younger (upper) leaves, which had lower C:N ratios. In addition, a detached leaf assay was conducted to investigate the effect of carbon/nitrogen availability on drought-induced senescence. Exogenous application of excess sugar combined with limited nitrogen promoted drought-induced leaf senescence. Thus our results suggest that the carbon/nitrogen balance may be involved in the regulation of drought-induced leaf senescence. PMID:26317421

  3. Stand Composition, Tree Proximity and Size Have Minimal Effects on Leaf Function of Coexisting Aspen and Subalpine Fir.

    PubMed

    Rhodes, Aaron C; Barney, Trevor; St Clair, Samuel B

    2016-01-01

    Forest structural heterogeneity due to species composition, spatial relationships and tree size are widely studied patterns in forest systems, but their impacts on tree function are not as well documented. The objective of this study was to examine how stand composition, tree proximity relationships and tree size influence the leaf functional traits of aspen, an early successional species, and subalpine fir, a climax species. We measured foliar nutrients, nonstructural carbohydrates (aspen only), defense chemistry and xylem water potential of aspen and subalpine fir trees in three size classes growing in close proximity or independently from other trees under three stand conditions: aspen dominant, aspen-conifer mixed, and conifer dominant stands. Close proximity of subalpine fir to aspen reduced aspen's storage of starch in foliar tissue by 17% suggesting that competition between these species may have small effects on carbon metabolism in aspen leaves. Simple sugar (glucose + sucrose) concentrations in aspen leaves were slightly higher in larger aspen trees than smaller trees. However, no differences were found in stem water potential, foliar concentrations of nitrogen, phosphorus, or secondary defense chemicals of aspen or subalpine fir across the gradients of stand composition, tree proximity or tree size. These results suggest that mechanisms of coexistence allow both aspen and subalpine fir to maintain leaf function across a wide range of stand structural characteristics. For aspen, resource sharing through its clonal root system and high resource storage capacity may partially contribute to its functional stability in mixed aspen-conifer stands. PMID:27124496

  4. Stand Composition, Tree Proximity and Size Have Minimal Effects on Leaf Function of Coexisting Aspen and Subalpine Fir

    PubMed Central

    Rhodes, Aaron C.; Barney, Trevor; St. Clair, Samuel B.

    2016-01-01

    Forest structural heterogeneity due to species composition, spatial relationships and tree size are widely studied patterns in forest systems, but their impacts on tree function are not as well documented. The objective of this study was to examine how stand composition, tree proximity relationships and tree size influence the leaf functional traits of aspen, an early successional species, and subalpine fir, a climax species. We measured foliar nutrients, nonstructural carbohydrates (aspen only), defense chemistry and xylem water potential of aspen and subalpine fir trees in three size classes growing in close proximity or independently from other trees under three stand conditions: aspen dominant, aspen-conifer mixed, and conifer dominant stands. Close proximity of subalpine fir to aspen reduced aspen’s storage of starch in foliar tissue by 17% suggesting that competition between these species may have small effects on carbon metabolism in aspen leaves. Simple sugar (glucose + sucrose) concentrations in aspen leaves were slightly higher in larger aspen trees than smaller trees. However, no differences were found in stem water potential, foliar concentrations of nitrogen, phosphorus, or secondary defense chemicals of aspen or subalpine fir across the gradients of stand composition, tree proximity or tree size. These results suggest that mechanisms of coexistence allow both aspen and subalpine fir to maintain leaf function across a wide range of stand structural characteristics. For aspen, resource sharing through its clonal root system and high resource storage capacity may partially contribute to its functional stability in mixed aspen-conifer stands. PMID:27124496

  5. Stand Composition, Tree Proximity and Size Have Minimal Effects on Leaf Function of Coexisting Aspen and Subalpine Fir.

    PubMed

    Rhodes, Aaron C; Barney, Trevor; St Clair, Samuel B

    2016-01-01

    Forest structural heterogeneity due to species composition, spatial relationships and tree size are widely studied patterns in forest systems, but their impacts on tree function are not as well documented. The objective of this study was to examine how stand composition, tree proximity relationships and tree size influence the leaf functional traits of aspen, an early successional species, and subalpine fir, a climax species. We measured foliar nutrients, nonstructural carbohydrates (aspen only), defense chemistry and xylem water potential of aspen and subalpine fir trees in three size classes growing in close proximity or independently from other trees under three stand conditions: aspen dominant, aspen-conifer mixed, and conifer dominant stands. Close proximity of subalpine fir to aspen reduced aspen's storage of starch in foliar tissue by 17% suggesting that competition between these species may have small effects on carbon metabolism in aspen leaves. Simple sugar (glucose + sucrose) concentrations in aspen leaves were slightly higher in larger aspen trees than smaller trees. However, no differences were found in stem water potential, foliar concentrations of nitrogen, phosphorus, or secondary defense chemicals of aspen or subalpine fir across the gradients of stand composition, tree proximity or tree size. These results suggest that mechanisms of coexistence allow both aspen and subalpine fir to maintain leaf function across a wide range of stand structural characteristics. For aspen, resource sharing through its clonal root system and high resource storage capacity may partially contribute to its functional stability in mixed aspen-conifer stands.

  6. Hormonal Regulation of Leaf Abscission

    PubMed Central

    Jacobs, William P.

    1968-01-01

    A review is given of the progress made during the last 6 years in elucidating the nature, locus of action, and transport properties of the endogenous hormones that control leaf abscission. PMID:16657014

  7. Experiments in Whole Leaf Photosynthesis

    ERIC Educational Resources Information Center

    Stewart, J. C.; And Others

    1974-01-01

    Described is a simple experimental system, which uses radioactive carbon dioxide to study whole leaf photosynthesis under a variety of conditions. Other experiments and simple apparatus for the experiments are also described. (Author/RH)

  8. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  9. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  10. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  11. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  12. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  13. [Correlations between leaf delta13C and physiological parameters of desert plant Reaumuria soongorica].

    PubMed

    Ma, Jian-Ying; Chen, Fa-Hu; Xia, Dun-Sheng; Sun, Hui-Ling; Duan, Zheng-Hu; Wang, Gang

    2008-05-01

    Reaumuria soongorica is a dominant species in the desert shrubbery vegetation in arid regions of northwestern China, playing an important role in the maintenance of the stability and continuity of desert ecosystem. In this paper, a total of 407 individuals in 21 natural populations of R. soongorica were selected from its main distribution areas to measure the leaf stable carbon isotope composition (delta13C) and nitrogen, phosphorus, potassium, water, proline and chlorophyll contents, with the correlations between the delta13C value and the test physiological parameters analyzed. The results showed that leaf delta13C value was significantly correlated with the contents of leaf potassium, water, and proline (P <0.001), and the correlation with leaf potassium content was most profound (r = 0.793), followed by that with leaf water content (r = -0.786), indicating that the variation of leaf delta13C value could reflect the nutritional status of the plants, and also, their water-deficient degree. The different distribution trends in leaf delta13C value of R. soongorica were likely caused by stomatal conductance, rather than by nutrient-related changes in photosynthetic efficiency under extremely low available water conditions.

  14. Temperature affects leaf litter decomposition in low-order forest streams: field and microcosm approaches.

    PubMed

    Martínez, Aingeru; Larrañaga, Aitor; Pérez, Javier; Descals, Enrique; Pozo, Jesús

    2014-01-01

    Despite predicted global warming, the temperature effects on headwater stream functioning are poorly understood. We studied these effects on microbial-mediated leaf decomposition and the performance of associated aquatic hyphomycete assemblages. Alder leaves were incubated in three streams differing in winter water temperature. Simultaneously, in laboratory, leaf discs conditioned in these streams were incubated at 5, 10 and 15 °C. We determined mass loss, leaf N and sporulation rate and diversity of aquatic hyphomycete communities. In the field, decomposition rate correlated positively with temperature. Decomposition rate and leaf N presented a positive trend with dissolved nutrients, suggesting that temperature was not the only factor determining the process velocity. Under controlled conditions, it was confirmed that decomposition rate and leaf N were positively correlated with temperature, leaves from the coldest stream responding most clearly. Sporulation rate correlated positively with temperature after 9 days of incubation, but negatively after 18 and 27 days. Temperature rise affected negatively the sporulating fungi richness and diversity only in the material from the coldest stream. Our results suggest that temperature is an important factor determining leaf processing and aquatic hyphomycete assemblages and that composition and activity of fungal communities adapted to cold environments could be more affected by temperature rises. Highlight: Leaf decomposition rate and associated fungal communities respond to temperature shifts in headwater streams. PMID:24111990

  15. Temperature affects leaf litter decomposition in low-order forest streams: field and microcosm approaches.

    PubMed

    Martínez, Aingeru; Larrañaga, Aitor; Pérez, Javier; Descals, Enrique; Pozo, Jesús

    2014-01-01

    Despite predicted global warming, the temperature effects on headwater stream functioning are poorly understood. We studied these effects on microbial-mediated leaf decomposition and the performance of associated aquatic hyphomycete assemblages. Alder leaves were incubated in three streams differing in winter water temperature. Simultaneously, in laboratory, leaf discs conditioned in these streams were incubated at 5, 10 and 15 °C. We determined mass loss, leaf N and sporulation rate and diversity of aquatic hyphomycete communities. In the field, decomposition rate correlated positively with temperature. Decomposition rate and leaf N presented a positive trend with dissolved nutrients, suggesting that temperature was not the only factor determining the process velocity. Under controlled conditions, it was confirmed that decomposition rate and leaf N were positively correlated with temperature, leaves from the coldest stream responding most clearly. Sporulation rate correlated positively with temperature after 9 days of incubation, but negatively after 18 and 27 days. Temperature rise affected negatively the sporulating fungi richness and diversity only in the material from the coldest stream. Our results suggest that temperature is an important factor determining leaf processing and aquatic hyphomycete assemblages and that composition and activity of fungal communities adapted to cold environments could be more affected by temperature rises. Highlight: Leaf decomposition rate and associated fungal communities respond to temperature shifts in headwater streams.

  16. Why do leaf-tying caterpillars abandon their leaf ties?

    PubMed

    Sliwinski, Michelle; Sigmon, Elisha

    2013-01-01

    Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats), but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm(2) leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently abandon their leaf

  17. Nutrient dynamics: Chapter 3

    USGS Publications Warehouse

    Likens, Gene E.; LaBaugh, James W.; Buso, Donald C.; Bade, Darren; Winter, Thomas C.; Likens, Gene E.

    2009-01-01

    This chapter focuses on the variability and trends in chemical concentrations and fluxes at Mirror Lake during the period 1981–2000. It examines the water and chemical budgets of Mirror Lake to identify and understand better long-term trends in the chemical characteristics of the lake. It also identifies the causes of changes in nutrient concentrations and examines the contribution of hydrologic pathways to the contamination of Mirror Lake by road salt. The role of groundwater and precipitation on water and chemical budgets of the lake are also examined.

  18. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf.

    PubMed

    Simonin, Kevin A; Burns, Emily; Choat, Brendan; Barbour, Margaret M; Dawson, Todd E; Franks, Peter J

    2015-03-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem-leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO₂ concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO₂ concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO₂ on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem-leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO₂ assimilation rate over the diurnal course of evaporative demand.

  19. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf

    PubMed Central

    Simonin, Kevin A.; Burns, Emily; Choat, Brendan; Barbour, Margaret M.; Dawson, Todd E.; Franks, Peter J.

    2015-01-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem–leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO2 concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO2 concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO2 on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem–leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO2 assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  20. Light-mediated constraints on leaf function correlate with leaf structure among deciduous and evergreen tree species.

    PubMed

    Green, D S; Kruger, E L

    2001-12-01

    Leaf structure has been shown to be an important determinant of leaf photosynthetic characteristics, yet the nature of this relationship remains ambiguous. It has been suggested that intra-leaf shading of chloroplasts may explain the negative influence of increasing leaf thickness/density on mass-based photosynthesis. To explore further the importance of light-mediated functional limitations conferred by leaf structure, we examined photosynthetic responses to high unidirectional and bidirectional irradiances among broad- and needle-leaves ranging widely in mass per area (LMA). Except for leaves with the lowest LMA (< 40 g m-2), photosynthesis increased in bidirectional irradiance, and the ratio of unidirectional to bidirectional photosynthesis (Au/Ab) was strongly and negatively related to LMA, approaching 0.5 for the thickest/densest leaves. Bidirectional illumination also increased stomatal conductance, but the magnitude of stomatal response was modest and uncorrelated with LMA. Consequently, the ratio of intercellular CO2 partial pressures during unidirectional versus bidirectional irradiation was positively related to LMA. Hence, it appears that many C3 leaves may not be "light saturated" under high unidirectional illumination. The negative, exponential Au/Ab-LMA relationship in this study supports the notion that, as LMA increases, an increasing fraction of leaf chloroplasts are functioning at subsaturating irradiance under unidirectional light.

  1. Neuroelectric assessment of nutrient intake.

    PubMed

    Hoffman, L D; Friedmann, A; Saltman, P; Polich, J

    1999-05-01

    Electroencephalographic (EEG) activity and auditory event-related brain potentials (ERPs) were assessed in two groups (n = 12 each) of subjects. The 'food-nutrient' group had fasted from the night before and consumed a 500 cal nutrient drink; the 'control' group consumed breakfast but did not consume any nutrients during the recordings. All subjects were assessed every 15 min for six trial blocks at the same time of day, with the fast/nutrient group measured initially before and after consuming the nutrient drink. No effects of the nutrient drink were obtained on the post-stimulus EEG spectral power or mean frequency measures. However, the fast/nutrient group demonstrated less delta, theta, and alpha-1 power than the no-fast/control group. Increases in spectral power were generally observed across trial blocks especially for the alpha and beta bands, and are consistent with increases in arousal level. P300 amplitude was unaffected by the nutrient consumption, but target stimulus N100 amplitude was smaller for the food-nutrient compared to the control group. Taken together, the results suggest that nutrient consumption does not directly affect EEG or cognitive ERP measures.

  2. Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand.

    PubMed

    Ishida, Atsushi; Diloksumpun, Sapit; Ladpala, Phanumard; Staporn, Duriya; Panuthai, Samreong; Gamo, Minoru; Yazaki, Kenichi; Ishizuka, Moriyoshi; Puangchit, Ladawan

    2006-05-01

    We compared differences in leaf properties, leaf gas exchange and photochemical properties between drought-deciduous and evergreen trees in tropical dry forests, where soil nutrients differed but rainfall was similar. Three canopy trees (Shorea siamensis Miq., Xylia xylocarpa (Roxb.) W. Theob. and Vitex peduncularis Wall. ex Schauer) in a drought-deciduous forest and a canopy tree (Hopea ferrea Lanessan) in an evergreen forest were selected. Soil nutrient availability is lower in the evergreen forest than in the deciduous forest. Compared with the evergreen tree, the deciduous trees had shorter leaf life spans, lower leaf masses per area, higher leaf mass-based nitrogen (N) contents, higher leaf mass-based photosynthetic rates (mass-based P(n)), higher leaf N-based P(n), higher daily maximum stomatal conductance (g(s)) and wider conduits in wood xylem. Mass-based P(n) decreased from the wet to the dry season for all species. Following onset of the dry season, daily maximum g(s) and sensitivity of g(s) to leaf-to-air vapor pressure deficit remained relatively unchanged in the deciduous trees, whereas both properties decreased in the evergreen tree during the dry season. Photochemical capacity and non-photochemical quenching (NPQ) of photosystem II (PSII) also remained relatively unchanged in the deciduous trees even after the onset of the dry season. In contrast, photochemical capacity decreased and NPQ increased in the evergreen tree during the dry season, indicating that the leaves coped with prolonged drought by down-regulating PSII. Thus, the drought-avoidant deciduous species were characterized by high N allocation for leaf carbon assimilation, high water use and photoinhibition avoidance, whereas the drought-tolerant evergreen was characterized by low N allocation for leaf carbon assimilation, conservative water use and photoinhibition tolerance.

  3. Combined effects of nitrogen addition and litter manipulation on nutrient resorption of Leymus chinensis in a semi-arid grassland of northern China.

    PubMed

    Li, X; Liu, J; Fan, J; Ma, Y; Ding, S; Zhong, Z; Wang, D

    2015-01-01

    Plant growth in semi-arid ecosystems is usually severely limited by soil nutrient availability. Alleviation of these resource stresses by fertiliser application and aboveground litter input may affect plant internal nutrient cycling in such regions. We conducted a 4-year field experiment to investigate the effects of nitrogen (N) addition (10 g N·m(-2) ·year(-1)) and plant litter manipulation on nutrient resorption of Leymus chinensis, the dominant native grass in a semi-arid grassland in northern China. Although N addition had no clear effects on N and phosphorus (P) resorption efficiencies in leaves and culms, N fertilisation generally decreased leaf N resorption proficiency by 54%, culm N resorption proficiency by 65%. Moreover, N fertilisation increased leaf P resorption proficiency by 13%, culm P resorption proficiency by 20%. Under ambient or enriched N conditions, litter addition reduced N and P resorption proficiencies in both leaves and culms. The response of P resorption proficiency to litter manipulation was more sensitive than N resorption proficiency: P resorption proficiency in leaves and culms decreased strongly with increasing litter amount under both ambient and enriched N conditions. In contrast, N resorption proficiency was not significantly affected by litter addition, except for leaf N resorption proficiency under ambient N conditions. Furthermore, although litter addition caused a general decrease of leaf and culm nutrient resorption efficiencies under both ambient and enriched N conditions, litter addition effects on nutrient resorption efficiency were much weaker than the effects of litter addition on nutrient resorption proficiency. Taken together, our results show that leaf and non-leaf organs of L. chinensis respond consistently to altered soil N availability. Our study confirms the strong effects of N addition on plant nutrient resorption processes and the potential role of aboveground litter, the most important natural fertiliser in

  4. Diurnal variation in leaf extension of Salix viminalis at two nitrogen supply rates.

    PubMed

    Stadenberg, I; McDonald, A J; Palmer, S

    1994-10-01

    To investigate how nitrogen supply might affect the biophysical factors controlling diurnal variation in leaf extension, pot-grown Salix viminalis L. were supplied with nitrogen at a low relative addition rate of 0.05 g N g(-1) N day(-1) (low N) or were given free access to all nutrients (high N). Leaf extension, turgor pressure, turgor after stress relaxation and the plastic extensibility of leaf tissue were determined for growing leaves every 4 h during two days of clear skies in August. Plants in the high-N treatment had a significantly higher relative growth rate, dry weight, shoot/root ratio, leaf nitrogen concentration, total leaf area, final area of single leaves and epidermal cell size than plants in the low-N treatment. The periodicity of leaf extension was similar in both treatments with high values during the afternoon and early evening, and negligible values during the night and in the early morning. The maximum rate of leaf extension was higher in high-N than in low-N plants. Leaf water potential and leaf osmotic potential decreased in the morning and increased in the afternoon with highest values during the night. Calculated values of turgor pressure showed no consistent diurnal trend and did not correlate with the rate of leaf extension. There was no consistent difference in turgor between treatments. Turgor after stress relaxation varied diurnally. The difference between turgors before and after stress relaxation also varied diurnally and was largely in phase with the diurnal pattern of leaf extension. These data are consistent with either a causal role for growth turgor (difference between turgors before and after stress relaxation) in the regulation of cell expansion, or a diurnal variation in turgors after relaxation, attributable to different capacities for cell wall loosening at different times of day. Plastic extensibility of leaf tissue showed no diurnal pattern but consistently higher values were found in high-N than in low-N plants. We

  5. WERF Nutrient Challenge investigates limits of nutrient removal technologies.

    PubMed

    Neethling, J B; Clark, D; Pramanik, A; Stensel, H D; Sandino, J; Tsuchihashi, R

    2010-01-01

    The WERF Nutrient Challenge is a multi-year collaborative research initiative established in 2007 to develop and provide current information about wastewater treatment nutrients (specifically nitrogen and phosphorus in wastewater), their characteristics, and bioavailability in aquatic environments to help regulators make informed decisions. The Nutrient Challenge will also provide data on nutrient removal so that treatment facilities can select sustainable, cost-effective methods and technologies to meet permit limits. To meet these goals, the Nutrient Challenge has teamed with a wide array of utilities, agencies, consultants, universities and other researchers and practitioners to collaborate on projects that advance these goals. The Nutrient Challenge is focusing on a different approach to collaborating and leveraging resources (financial and intellectual) on research projects by targeting existing projects and research that correspond with its goals and funding those aspects that the Nutrient Challenge identified as a priority. Because the Nutrient Challenge is focused on collaboration, outreach is an absolutely necessary component of its effectiveness. Through workshops, webinars, a web portal and online compendium, published papers, and conference lectures, the Nutrient Challenge is both presenting important new information, and soliciting new partnerships.

  6. Nutrient Status of Adults with Cystic Fibrosis

    PubMed Central

    GORDON, CATHERINE M.; ANDERSON, ELLEN J.; HERLYN, KAREN; HUBBARD, JANE L.; PIZZO, ANGELA; GELBARD, RONDI; LAPEY, ALLEN; MERKEL, PETER A.

    2011-01-01

    Nutrition is thought to influence disease status in patients with cystic fibrosis (CF). This cross-sectional study sought to evaluate nutrient intake and anthropometric data from 64 adult outpatients with cystic fibrosis. Nutrient intake from food and supplements was compared with the Dietary Reference Intakes for 16 nutrients and outcomes influenced by nutritional status. Attention was given to vitamin D and calcium given potential skeletal implications due to cystic fibrosis. Measurements included weight, height, body composition, pulmonary function, and serum metabolic parameters. Participants were interviewed about dietary intake, supplement use, pulmonary function, sunlight exposure, and pain. The participants’ mean body mass index (±standard deviation) was 21.8±4.9 and pulmonary function tests were normal. Seventy-eight percent used pancreatic enzyme replacement for malabsorption. Vitamin D deficiency [25-hydroxyvitamin D (25OHD)<37.5 nmol/L] was common: 25 (39%) were deficient despite adequate vitamin D intake. Lipid profiles were normal in the majority, even though total and saturated fat consumption represented 33.0% and 16.8% of energy intake, respectively. Reported protein intake represented 16.9% of total energy intake (range 10%–25%). For several nutrients, including vitamin D and calcium, intake from food and supplements in many participants exceeded recommended Tolerable Upper Intake Levels. Among adults with cystic fibrosis, vitamin D deficiency was common despite reported adequate intake, and lipid profiles were normal despite a relatively high fat intake. Mean protein consumption was adequate, but the range of intake was concerning, as both inadequate or excessive intake may have deleterious skeletal effects. These findings call into question the applicability of established nutrient thresholds for patients with cystic fibrosis. PMID:18060897

  7. Leaf area and foliar biomass relationships in northern hardwood forests located along an 800 km acid deposition gradient

    SciTech Connect

    Burton, A.J.; Pregitzer, K.S. ); Reed, D.D. )

    1991-09-01

    The canopies of northern hardwood forests dominated by sugar maple (Acer saccharum Marsh.) were examined at five locations spanning 800 km along an acid deposition and climatic gradient in the Great Lakes region. Leaf area index (LAI) calculated from litterfall ranged from 6.0 to 8.0 in 1988, from 4.9 to 7.9 in 1989, and from 5.3 to 7.8 in 1990. The data suggest that maximum LAI for the sites is between 7 and 8. Insect defoliation and the allocation of assimilates to reproductive parts in large seed years reduced LAI by up to 34%. Allometric equations for leaf area and foliar biomass were not significantly different among sites. They predicted higher LAI values than were estimated from litterfall and could not account for the influences of defoliation and seed production. Canopy transmittance was a viable alternative for estimating LAI. Extinction coefficients (K) of 0.49 to 0.65 were appropriate for solar elevations of 63{degree} to 41{degree}. Patterns of specific leaf area (SLA) were similar for the sites. Average sugar maple SLA increased from 147 cm{sup 2}g{sup {minus}1} in the upper 5 m of the canopy to 389 cm{sup 2}g{sup {minus}1} in the seeding layer. Litterfall SLA averaged 196 cm{sup 2}g{sup {minus}1} for all species and 192 cm{sup 2}g{sup {minus}1} for sugar maple. Similarity among the sites in allometric relationships, maximum LAI, canopy transmittance, and patterns of SLA suggests these characteristics were controlled primarily by the similar nutrient and moisture availability at the sites. A general increasing trend in litter production along the gradient could not be attributed to N deposition or length of growing season due to year to year variability resulting from insect defoliation and seed production.

  8. Optimal foraging for specific nutrients in predatory beetles

    PubMed Central

    Jensen, Kim; Mayntz, David; Toft, Søren; Clissold, Fiona J.; Hunt, John; Raubenheimer, David; Simpson, Stephen J.

    2012-01-01

    Evolutionary theory predicts that animals should forage to maximize their fitness, which in predators is traditionally assumed equivalent to maximizing energy intake rather than balancing the intake of specific nutrients. We restricted female predatory ground beetles (Anchomenus dorsalis) to one of a range of diets varying in lipid and protein content, and showed that total egg production peaked at a target intake of both nutrients. Other beetles given a choice to feed from two diets differing only in protein and lipid composition selectively ingested nutrient combinations at this target intake. When restricted to nutritionally imbalanced diets, beetles balanced the over- and under-ingestion of lipid and protein around a nutrient composition that maximized egg production under those constrained circumstances. Selective foraging for specific nutrients in this predator thus maximizes its reproductive performance. Our findings have implications for predator foraging behaviour and in the structuring of ecological communities. PMID:22237910

  9. Intra-annual nutrient flux in Pinus taeda.

    PubMed

    Albaugh, Timothy J; Allen, H Lee; Stape, Jose L; Fox, Thomas R; Rubilar, Rafael A; Price, James W

    2012-10-01

    Intra-annual nutrient (nitrogen, phosphorus, potassium, calcium and magnesium) flux was quantified for Pinus taeda L. at a nutrient-poor, well-drained sandy site in Scotland County, NC, USA where a 2 × 2 factorial of irrigation and nutrition was applied in four replications in a 10-year-old stand with 1200 stems ha(-1). Treatments were applied with the goal of providing optimum nutrition (no nutritional deficiencies) and water availability. Component (foliage, branch, stem and root) nutrient content was estimated monthly for 2 years using nutrient concentration and phenology assessments combined with destructive harvests. Positive flux values indicated nutrient accumulation in the trees while negative values indicated nutrient loss from the trees. Fertilization significantly increased nitrogen, phosphorus, potassium, calcium and magnesium flux 140%, on average, over non-fertilized. Irrigation significantly increased calcium flux 28% while there was no significant irrigation effect on nitrogen, phosphorus, potassium or magnesium. Maximum nutrient fluxes (kg ha(-1) day(-1)) for non-fertilized and fertilized stands were 0.36 and 1.05 for nitrogen, 0.042 and 0.095 for phosphorus, 0.13 and 0.51 for potassium, 0.27 and 0.42 for calcium, and 0.04 and 0.12 for magnesium, respectively. Maximum flux was coincident with ephemeral tissue (foliage and fine root) development and likely would be higher in stands with more foliage than those observed in this study (projected leaf area indices were 1.5 and 3.0 for the non-fertilized and fertilized stands). Minimum nutrient fluxes (kg ha(-1) day(-1)) for non-fertilized and fertilized stands were -0.18 and -0.42 for nitrogen, -0.029 and -0.070 for phosphorus, -0.05 and -0.18 for potassium, -0.04 and -0.05 for calcium, and -0.02 and -0.03 for magnesium, respectively. Minimum fluxes were typically observed in the dormant season and were linked to foliage senescence and branch death. Foliage and branch component nutrient contents

  10. Interaction between Silver Nanoparticles and Spinach Leaf

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

    2013-12-01

    Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. Cyto

  11. The effects of elevated CO2 on clonal growth and nutrient content of submerge plant Vallisneria spinulosa.

    PubMed

    Yan, Xue; Yu, Dan; Li, Yong-Ke

    2006-01-01

    An approximately four months long glasshouse experiment was conducted to examine the effects of elevated carbon dioxide (CO(2)) concentration (1,000 +/- 50 micromol mol(-1)) in the atmosphere on biomass accumulation and allocation pattern, clonal growth and nitrogen (N), phosphorus (P) accumulation by the submerged plant Vallisneria spinulosa Yan. Elevated CO(2) significantly increased V. spinulosa total fresh biomass ( approximately 130%) after 120 days, due to more biomass accumulation in all morphological organs than in those at ambient CO(2) (390 +/- 20 micromol mol(-1)). About 75% of the additional total biomass at elevated CO(2) was accounted for by leaf and rhizome (above ground) biomass and only 25% of it belonged to root and turion (below ground). However, the turions biomass exhibited a greater increase rate than that of organ above ground, which caused reduction in the above/below ground biomass ratio. The clonal growth of V. spinulosa responded positively to elevated CO(2). The number of primary ramets increased up to 1.4-folds at elevated CO(2) and induced a dense growth pattern. For nutrients absorption, concentration of N in leaf and in turion was significantly (p ranging from 35% to 147%, except for turion. Compared with those in ambient CO(2), the mean accumulation per ramet of N and P significantly higher in elevated CO(2). These results showed that elevated CO(2) could promote submerged plant biomass accumulation, and it should be an adaptive strategy for clonal plants to increase the nutrient absorption efficiency of root and reproduce more clonal ramets to exploit enough resources to match with higher growth in elevated CO(2).

  12. The effects of elevated CO2 on clonal growth and nutrient content of submerge plant Vallisneria spinulosa.

    PubMed

    Yan, Xue; Yu, Dan; Li, Yong-Ke

    2006-01-01

    An approximately four months long glasshouse experiment was conducted to examine the effects of elevated carbon dioxide (CO(2)) concentration (1,000 +/- 50 micromol mol(-1)) in the atmosphere on biomass accumulation and allocation pattern, clonal growth and nitrogen (N), phosphorus (P) accumulation by the submerged plant Vallisneria spinulosa Yan. Elevated CO(2) significantly increased V. spinulosa total fresh biomass ( approximately 130%) after 120 days, due to more biomass accumulation in all morphological organs than in those at ambient CO(2) (390 +/- 20 micromol mol(-1)). About 75% of the additional total biomass at elevated CO(2) was accounted for by leaf and rhizome (above ground) biomass and only 25% of it belonged to root and turion (below ground). However, the turions biomass exhibited a greater increase rate than that of organ above ground, which caused reduction in the above/below ground biomass ratio. The clonal growth of V. spinulosa responded positively to elevated CO(2). The number of primary ramets increased up to 1.4-folds at elevated CO(2) and induced a dense growth pattern. For nutrients absorption, concentration of N in leaf and in turion was significantly (p ranging from 35% to 147%, except for turion. Compared with those in ambient CO(2), the mean accumulation per ramet of N and P significantly higher in elevated CO(2). These results showed that elevated CO(2) could promote submerged plant biomass accumulation, and it should be an adaptive strategy for clonal plants to increase the nutrient absorption efficiency of root and reproduce more clonal ramets to exploit enough resources to match with higher growth in elevated CO(2). PMID:16083940

  13. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies

    EPA Science Inventory

    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 &ldq...

  14. Lateral Diffusion of Nutrients by Mammalian Herbivores in Terrestrial Ecosystems

    PubMed Central

    Wolf, Adam; Doughty, Christopher E.; Malhi, Yadvinder

    2013-01-01

    Animals translocate nutrients by consuming nutrients at one point and excreting them or dying at another location. Such lateral fluxes may be an important mechanism of nutrient supply in many ecosystems, but lack quantification and a systematic theoretical framework for their evaluation. This paper presents a mathematical framework for quantifying such fluxes in the context of mammalian herbivores. We develop an expression for lateral diffusion of a nutrient, where the diffusivity is a biologically determined parameter depending on the characteristics of mammals occupying the domain, including size-dependent phenomena such as day range, metabolic demand, food passage time, and population size. Three findings stand out: (a) Scaling law-derived estimates of diffusion parameters are comparable to estimates calculated from estimates of each coefficient gathered from primary literature. (b) The diffusion term due to transport of nutrients in dung is orders of magnitude large than the coefficient representing nutrients in bodymass. (c) The scaling coefficients show that large herbivores make a disproportionate contribution to lateral nutrient transfer. We apply the diffusion equation to a case study of Kruger National Park to estimate the conditions under which mammal-driven nutrient transport is comparable in magnitude to other (abiotic) nutrient fluxes (inputs and losses). Finally, a global analysis of mammalian herbivore transport is presented, using a comprehensive database of contemporary animal distributions. We show that continents vary greatly in terms of the importance of animal-driven nutrient fluxes, and also that perturbations to nutrient cycles are potentially quite large if threatened large herbivores are driven to extinction. PMID:23951141

  15. Thermal acclimation of shoot respiration in an Arctic woody plant species subjected to 22 years of warming and altered nutrient supply.

    PubMed

    Heskel, Mary A; Greaves, Heather E; Turnbull, Matthew H; O'Sullivan, Odhran S; Shaver, Gaius R; Griffin, Kevin L; Atkin, Owen K

    2014-08-01

    Despite concern about the status of carbon (C) in the Arctic tundra, there is currently little information on how plant respiration varies in response to environmental change in this region. We quantified the impact of long-term nitrogen (N) and phosphorus (P) treatments and greenhouse warming on the short-term temperature (T) response and sensitivity of leaf respiration (R), the high-T threshold of R, and associated traits in shoots of the Arctic shrub Betula nana in experimental plots at Toolik Lake, Alaska. Respiration only acclimated to greenhouse warming in plots provided with both N and P (resulting in a ~30% reduction in carbon efflux in shoots measured at 10 and 20 °C), suggesting a nutrient dependence of metabolic adjustment. Neither greenhouse nor N+P treatments impacted on the respiratory sensitivity to T (Q10 ); overall, Q10 values decreased with increasing measuring T, from ~3.0 at 5 °C to ~1.5 at 35 °C. New high-resolution measurements of R across a range of measuring Ts (25-70 °C) yielded insights into the T at which maximal rates of R occurred (Tmax ). Although growth temperature did not affect Tmax , N+P fertilization increased Tmax values ~5 °C, from 53 to 58 °C. N+P fertilized shoots exhibited greater rates of R than nonfertilized shoots, with this effect diminishing under greenhouse warming. Collectively, our results highlight the nutrient dependence of thermal acclimation of leaf R in B. nana, suggesting that the metabolic efficiency allowed via thermal acclimation may be impaired at current levels of soil nutrient availability. This finding has important implications for predicting carbon fluxes in Arctic ecosystems, particularly if soil N and P become more abundant in the future as the tundra warms.

  16. Isotopic characteristics of canopies in simulated leaf assemblages

    NASA Astrophysics Data System (ADS)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the "canopy effect" could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the

  17. Scaling, propagating and mapping uncertainty in spectroscopy-derived foliar traits from the leaf to the image

    NASA Astrophysics Data System (ADS)

    Singh, A.; Serbin, S. P.; Kingdon, C.; Townsend, P. A.

    2013-12-01

    A major goal of remote sensing, and imaging spectroscopy in particular, is the development of generalizable algorithms to repeatedly and accurately map ecosystem properties such as canopy chemistry across space and time. Existing methods must therefore be tested across a range of measurement approaches to identify and overcome limits to the consistent retrieval of such properties from spectroscopic imagery. Here we illustrate a general approach for the estimation of key foliar biochemical and morphological traits from spectroscopic imagery derived from the AVIRIS instrument and the propagation of errors from the leaf to the image scale using partial least squares regression (PLSR) techniques. Our method involves the integration of three types of data representing different scales of observation: At the image scale, the images were normalized for atmospheric, illumination and BRDF effects. Spectra from field plot locations were extracted from the 51AVIRIS images and were averaged when the field plot was larger than a single pixel. At the plot level, the scaling was conducted using multiple replicates (1000) derived from the leaf-level uncertainty estimates to generate plot-level estimates with their associated uncertainties. Leaf-level estimates of foliar traits (%N, %C, %Fiber, %Cellulose, %Lignin, LMA) were scaled to the canopy based on relative species composition of each plot. Image spectra were iteratively split into 50/50 randomized calibration-validation datasets and multiple (500) trait-predictive PLSR models were generated, this time sampling from within the plot-level uncertainty distribution. This allowed the propagation of uncertainty from the leaf-level dependent variables to the plot level, and finally to models built using AVIRIS image spectra. Moreover, this method allows us to generate spatially explicit maps of uncertainty in our sampled traits. Both LMA and %N PLSR models had a R2 greater than 0.8, root mean square errors (RMSEs) for both

  18. Nutrient Sensing Mechanisms and Pathways

    PubMed Central

    Efeyan, Alejo; Comb, William C.; Sabatini, David M.

    2015-01-01

    PREFACE The ability to sense and respond to fluctuations in environmental nutrient levels is a requisite for life. Nutrient scarcity is a selective pressure that has shaped the evolution of most cellular processes. Different pathways that detect intracellular and extracellular levels of sugars, amino acids and lipids, and surrogate metabolites, are then integrated and coordinated at the organismal level via hormonal signals. During food abundance, nutrient sensing pathways engage anabolism and storage, and scarcity triggers homeostatic mechanisms, like the mobilization of internal stores through mechanisms such as autophagy. Nutrient sensing pathways are commonly deregulated in human metabolic diseases. PMID:25592535

  19. Linkage between canopy water storage and drop size distributions of leaf drips

    NASA Astrophysics Data System (ADS)

    Nanko, Kazuki; Watanabe, Ai; Hotta, Norifumi; Suzuki, Masakazu

    2013-04-01

    Differences in drop size distribution (DSD) of leaf drips among tree species have been estimated and physically interpreted to clarify the leaf drip generation process. Leaf drip generation experiments for nine species were conducted in an indoor location without foliage vibration using an automatic mist spray. Broad-leaved species produced a similar DSD among species whose leaves had a matte surface and a second similar DSD among species whose leaves had a coated surface. The matte broad leaves produced a larger and wider range of DSDs than the coated broad leaves. Coated coniferous needles had a wider range of DSDs than the coated broad leaves and different DSDs were observed for different species. The species with shorter dense needles generated a larger DSD. The leaf drip diameter was calculated through the estimation of a state of equilibrium of a hanging drop on the leaves based on physical theory. The calculations indicated that the maximum diameter of leaf drips was determined by the contact angle, and the range of DSDs was determined by the variation in contact length and the contact diameter at the hanging points. The results revealed that leaf drip DSD changed due to variations in leaf hydrophobicity, leaf roughness, leaf geometry and leaf inclination among the different tree species. This study allows the modelization of throughfall DSD. Furthermore, it indicates the possibility of interpreting canopy water processes from canopy water storage to drainage through the contact angle and leaf drip DSD. The part of this study is published in Nanko et al. (2013, Agric. Forest. Meteorol. 169, 74-84).

  20. The effect of nutrient enrichment on growth, photosynthesis and hydraulic conductance of dwarf mangroves in Panamá

    USGS Publications Warehouse

    Lovelock, C.E.; Feller, Ilka C.; McKee, K.L.; Engelbrecht, B.M.J.; Ball, M.C.

    2004-01-01

    1. Dwarf stands of the mangrove Rhizophora mangle L. are extensive in the Caribbean. We fertilized dwarf trees in Almirante Bay, Bocas del Toro Province, north-eastern Panama with nitrogen (N) and phosphorus (P) to determine (1) if growth limitations are due to nutrient deficiency; and (2) what morphological and/or physiological factors underlie nutrient limitations to growth. 2. Shoot growth was 10-fold when fertilized with P and twofold with N fertilization, indicating that stunted growth of these mangroves is partially due to nutrient deficiency. 3. Growth enhancements caused by N or P enrichment could not be attributed to increases in photosynthesis on a leaf area basis, although photosynthetic nutrient-use efficiency was improved. The most dramatic effect was on stem hydraulic conductance, which was increased sixfold by P and 2-5-fold with N enrichment. Fertilization with P enhanced leaf and stem P concentrations and reduced C:N ratio, but did not alter leaf damage by herbivores. 4. Our findings indicate that addition of N and P significantly alter tree growth and internal nutrient dynamics of mangroves at Bocas del Toro, but also that the magnitude, pattern and mechanisms of change will be differentially affected by each nutrient.

  1. Nutrient Cycling Study

    SciTech Connect

    Peter A. Pryfogle

    2005-09-01

    The particular goal of this study is to develop measurement techniques for understanding how consortia of organisms from geothermal facilities utilize sulfur and iron for metabolic activity; and in turn, what role that activity plays in initiating or promoting the development of a biofilm on plant substrates. Sulfur cycling is of interest because sulfur is produced in the resource. Iron is found in some of the steel formulations used in plant components and is also added as chemical treatment for reducing sulfide emissions from the plants. This report describes the set-up and operation of a bioreactor for evaluating the response of colonies of geothermal organisms to changes in nutrient and environmental conditions. Data from initial experiments are presented and plans for future testing is discussed.

  2. Nutrients and neurodevelopment: lipids.

    PubMed

    González, Horacio F; Visentin, Silvana

    2016-10-01

    Nutrients, lipids in particular, make up the central nervous system structure and play major functional roles: they stimulate development, migration, and nerve cell differentiation. They are part of gray matter, white matter, nerve nuclei, and synaptogenesis. Breast milk contains lipids which are crucial for infant brain development. The lipid profile of breast milk was used as a guideline for the development of breast milk substitutes. However, to date, no substitute has matched it. Complementary feeding should include docosahexaenoic acid, arachidonic acid, other polyunsaturated fatty acids, saturated fatty acids, and complex lipids found in milk fat. The lipid composition of breast milk depends on maternal intake and nutritional status during pregnancy and breast-feeding. It has a great impact on development. Our goal is to review scientific literature regarding the role of lipids on infant brain development and the importance of breast milk lipid composition, maternal diet, and complementary feeding. PMID:27606648

  3. Nutrients and neurodevelopment: lipids.

    PubMed

    González, Horacio F; Visentin, Silvana

    2016-10-01

    Nutrients, lipids in particular, make up the central nervous system structure and play major functional roles: they stimulate development, migration, and nerve cell differentiation. They are part of gray matter, white matter, nerve nuclei, and synaptogenesis. Breast milk contains lipids which are crucial for infant brain development. The lipid profile of breast milk was used as a guideline for the development of breast milk substitutes. However, to date, no substitute has matched it. Complementary feeding should include docosahexaenoic acid, arachidonic acid, other polyunsaturated fatty acids, saturated fatty acids, and complex lipids found in milk fat. The lipid composition of breast milk depends on maternal intake and nutritional status during pregnancy and breast-feeding. It has a great impact on development. Our goal is to review scientific literature regarding the role of lipids on infant brain development and the importance of breast milk lipid composition, maternal diet, and complementary feeding.

  4. Uptake of Pharmaceuticals Influences Plant Development and Affects Nutrient and Hormone Homeostases.

    PubMed

    Carter, Laura J; Williams, Mike; Böttcher, Christine; Kookana, Rai S

    2015-10-20

    The detection of a range of active pharmaceutical ingredients (APIs) in the soil environment has led to a number of publications demonstrating uptake by crops, however very few studies have explored the potential for impacts on plant development as a result of API uptake. This study investigated the effect of carbamazepine and verapamil (0.005-10 mg/kg) on a range of plant responses in zucchini (Cucurbita pepo). Uptake increased in a dose-dependent manner, with maximum leaf concentrations of 821.9 and 2.2 mg/kg for carbamazepine and verapamil, respectively. Increased carbamazepine uptake by zucchini resulted in a decrease in above (<60%) and below (<30%) ground biomass compared to the controls (p < 0.05). At soil concentrations >4 mg/kg the mature leaves suffered from burnt edges and white spots as well as a reduction in photosynthetic pigments but no such effects were seen for verapamil. For both APIs, further investigations revealed significant differences in the concentrations of selected plant hormones (auxins, cytokinins, abscisic acid and jasmonates), and in the nutrient composition of the leaves in comparison to the controls (p < 0.05). This is some of the first research to demonstrate that the exposure of plants to APIs is likely to cause impacts on plant development with unknown implications.

  5. Uptake of Pharmaceuticals Influences Plant Development and Affects Nutrient and Hormone Homeostases.

    PubMed

    Carter, Laura J; Williams, Mike; Böttcher, Christine; Kookana, Rai S

    2015-10-20

    The detection of a range of active pharmaceutical ingredients (APIs) in the soil environment has led to a number of publications demonstrating uptake by crops, however very few studies have explored the potential for impacts on plant development as a result of API uptake. This study investigated the effect of carbamazepine and verapamil (0.005-10 mg/kg) on a range of plant responses in zucchini (Cucurbita pepo). Uptake increased in a dose-dependent manner, with maximum leaf concentrations of 821.9 and 2.2 mg/kg for carbamazepine and verapamil, respectively. Increased carbamazepine uptake by zucchini resulted in a decrease in above (<60%) and below (<30%) ground biomass compared to the controls (p < 0.05). At soil concentrations >4 mg/kg the mature leaves suffered from burnt edges and white spots as well as a reduction in photosynthetic pigments but no such effects were seen for verapamil. For both APIs, further investigations revealed significant differences in the concentrations of selected plant hormones (auxins, cytokinins, abscisic acid and jasmonates), and in the nutrient composition of the leaves in comparison to the controls (p < 0.05). This is some of the first research to demonstrate that the exposure of plants to APIs is likely to cause impacts on plant development with unknown implications. PMID:26418514

  6. Shifts in leaf litter breakdown along a forest-pasture-urban gradient in Andean streams.

    PubMed

    Iñiguez-Armijos, Carlos; Rausche, Sirkka; Cueva, Augusta; Sánchez-Rodríguez, Aminael; Espinosa, Carlos; Breuer, Lutz

    2016-07-01

    Tropical montane ecosystems of the Andes are critically threatened by a rapid land-use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest-pasture-urban) on stream physico-chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico-chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land-use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf-shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land-use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of

  7. Shifts in leaf litter breakdown along a forest-pasture-urban gradient in Andean streams.

    PubMed

    Iñiguez-Armijos, Carlos; Rausche, Sirkka; Cueva, Augusta; Sánchez-Rodríguez, Aminael; Espinosa, Carlos; Breuer, Lutz

    2016-07-01

    Tropical montane ecosystems of the Andes are critically threatened by a rapid land-use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest-pasture-urban) on stream physico-chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico-chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land-use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf-shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land-use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of

  8. How to pattern a leaf.

    PubMed

    Bolduc, N; O'Connor, D; Moon, J; Lewis, M; Hake, S

    2012-01-01

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, and function, all leaves initiate in the same manner: from the flanks of a meristem. The maize leaf is useful for analysis of patterning due to the wealth of mutants and the distinct tissues along the proximal distal axis. The blade is distal, the sheath is proximal, and the ligule forms at the blade/sheath boundary. Establishment of this boundary involves the transcription factors LIGULELESS1 and LIGULELESS2 and the kinase LIGULELESS NARROW. The meristem-specific protein KNOTTED1 (KN1) binds and modulates the lg2 gene. Given the localization of KN1 at the proximal end of the leaf from the time of inception, we hypothesize that KN1 has a role in establishing the very proximal end of the leaf, whereas an auxin maximum guides the growing distal tip. PMID:23174765

  9. Variation in defence strategies in two species of the genus Beilschmiedia under differing soil nutrient and rainfall conditions.

    PubMed

    Simon, J; Miller, R E; Woodrow, I E

    2007-01-01

    The relationships between various leaf functional traits that are important in plant growth (e.g., specific leaf area) have been investigated in recent studies; however, research in this context on plants that are highly protected by chemical defences, particularly resource-demanding nitrogen-based defence, is lacking. We collected leaves from cyanogenic (N-defended) Beilschmiedia collina B. Hyland and acyanogenic (C-defended) Beilschmiedia tooram (F. M. Bailey) B. Hyland at high- and low-soil nutrient sites in two consecutive years that varied significantly in rainfall. We then measured the relationships between chemical defence and morphological and functional leaf traits under the different environmental conditions. We found that the two species differed significantly in their resource allocation to defence as well as leaf morphology and function. The N defended species had a higher leaf nitrogen concentration, whereas the C-defended species had higher amounts of C-based chemical defences (i.e., total phenolics and condensed tannins). The C-defended species also tended to have higher force to fracture and increased leaf toughness. In B. collina, cyanogenic glycoside concentration was higher with higher rainfall, but not with higher soil nutrients. Total phenolic concentration was higher at the high soil nutrient site in B. tooram, but lower in B. collina; however, with higher rainfall an increase was found in B. tooram, while phenolics decreased in B. collina. Condensed tannin concentration decreased in both species with rainfall and nutrient availability. We conclude that chemical defence is correlated with leaf functional traits and that variation in environmental resources affects this correlation.

  10. Effect of two natural light regimes and nutrient addition on the forest herb Begonia decandra (Begoniaceae).

    PubMed

    Cordero, R A

    2000-01-01

    The effect of two natural light-growing conditions (understory versus light gaps) and the interaction with nutrient availability (through fertilization) were studied in the understory herb Begonia decandra, in the Luquillo Experimental Forest in Puerto Rico. Sixteen potted plants obtained from cuttings were randomly chosen and distributed in each of eighth forest environments (four light gaps and four understories), for a total of 128 plants. Fertilizer was applied to half of the plants in each site. After seven months in the two given microenvironments, increased light and fertilization resulted in greater growth and some changes in the biomass allocation patterns. All measured variables responded similarly to reported changes for tree seedlings and saplings from other tropical and subtropical regions. Total growth parameters (height, biomass and leaf area) were very sensitive to increases in the main resource (light). The addition of nutrients was less important in producing changes in the allocation variables (root to shoot ratio, leaf area ratio, and specific leaf mass) under conditions of high light availability. Changes due to nutrient levels were relatively greater on plants grown under under-story conditions. Also, small light differences among sites can cause significant changes in the variables related to total growth. Lastly, plant mortality in the nutrient treatments was found to be independent of mortality in two forest light environments. Some hypotheses about resource acquisition and plant growth are not supported by this data.

  11. The Mauna Loa environmental matrix: foliar and soil nutrients

    USGS Publications Warehouse

    Vitousek, P.M.; Aplet, G.; Turner, D.; Lockwood, J.J.

    1992-01-01

    The accumulation of total carbon, nitrogen, and phosphorus in soils, available soil nutrients, and foliar nutrients in the native dominant Metrosideros polymorpha were determined across a wide elevational range on 9 lava flows on Mauna Loa, Hawai'i. The flows included a young (2800 y) a??a?? (rough surface texture) and pa??hoehoe (smooth) flow on the wet east and dry northwest side of the mountain. Soil element pools and nutrient availability increased with flow age independent of climate. The dry sites accumulated organic matter and nutrients more slowly than comparable wet sites, but relative nutrient availability to plants (as indicated by soil assays and foliar nutrients) was greater in the dry sites. Accumulation of soil organic matter and nutrients occurred most rapidly in lowerelevation sites on the young flows, but the largest accumulations occurred at higher elevations on old flows. The range of sites sampled represents a complete and largely independent matrix of major factors governing ecosystem structure and function. ?? 1992 Springer-Verlag.

  12. Nutrient loading alters the performance of key nutrient exchange mutualisms.

    PubMed

    Shantz, Andrew A; Lemoine, Nathan P; Burkepile, Deron E

    2016-01-01

    Nutrient exchange mutualisms between phototrophs and heterotrophs, such as plants and mycorrhizal fungi or symbiotic algae and corals, underpin the functioning of many ecosystems. These relationships structure communities, promote biodiversity and help maintain food security. Nutrient loading may destabilise these mutualisms by altering the costs and benefits each partner incurs from interacting. Using meta-analyses, we show a near ubiquitous decoupling in mutualism performance across terrestrial and marine environments in which phototrophs benefit from enrichment at the expense of their heterotrophic partners. Importantly, heterotroph identity, their dependence on phototroph-derived C and the type of nutrient enrichment (e.g. nitrogen vs. phosphorus) mediated the responses of different mutualisms to enrichment. Nutrient-driven changes in mutualism performance may alter community organisation and ecosystem processes and increase costs of food production. Consequently, the decoupling of nutrient exchange mutualisms via alterations of the world's nitrogen and phosphorus cycles may represent an emerging threat of global change. PMID:26549314

  13. Capability of models to predict leaf N and P across four seasons for six sub-tropical forest evergreen trees

    NASA Astrophysics Data System (ADS)

    van Deventer, H.; Cho, M. A.; Mutanga, O.; Ramoelo, A.

    2015-03-01

    Nutrient phenology of evergreen subtropical forests of southern Africa is poorly understood. Foliar nitrogen (N) and phosphorous (P) forms key components of photosynthesis and are vulnerable to global change stressors. Remote sensing techniques can potentially map and monitor nutrient phenology, yet models to predict across species, seasons and climatic regions are deficient. This study evaluates the capability of various models, developed from leaf spectra of selected spectral regions and seasons, to predict nutrient concentration across season and species. Seasonal differences in foliar N and P were assessed using a one-way ANalysis Of VAriance (ANOVA). The relationship between leaf spectra and nutrients was assessed using linear regressions between the foliar nutrients and spectral indices. The predictive capability of three models was compared using root mean square error (RMSE) values. Amongst the four seasons, winter leaves showed the highest mean N (2.16%, p < 0.01). However, winter showed the lowest variability of foliar N (coefficient of variation = 8%) compared to the variability of the other three seasons (coefficient of variance > 35%). In fact, between winter and spring, the variability in foliar N increased by 294%. Foliar P did not significantly differ between the four seasons. Predictive models for leaf N concentration developed for each season showed a higher level of accuracy, particularly for winter, whereas predictive models for leaf P showed low accuracies. Models developed from a single season showed a slight increase in error for the summer and autumn, however a larger increase in error for the winter season for the evergreen trees. The results suggest that spectral measurements can be potentially be used to quantify nutrient phenology at regional scale and monitor the impacts of global change on nutrient phenology and photosynthesis.

  14. Radiation-use efficiency and gas exchange responses to water and nutrient availability in irrigated and fertilized stands of sweetgum and sycamore.

    PubMed

    Allen, Christopher B; Will, Rodney E; McGarvey, Robert C; Coyle, David R; Coleman, Mark D

    2005-02-01

    We investigated how water and nutrient availability affect radiation-use efficiency (epsilon) and assessed leaf gas exchange as a possible mechanism for shifts in epsilon. We measured aboveground net primary production (ANPP) and annual photosynthetically active radiation (PAR) capture to calculate epsilon as well as leaf-level physiological variables (light-saturated net photosynthesis, Asat; stomatal conductance, gs; leaf internal CO2 concentration, Ci; foliar nitrogen concentration, foliar [N]; and midday leaf water potential, Psileaf) during the second (2001) and third (2002) growing seasons in sweetgum (Liquidambar styraciflua L.) and sycamore (Platanus occidentalis L.) stands receiving a factorial combination of irrigation and fertilization at the Savannah River Site, South Carolina. Irrigation and fertilization increased PAR capture (maximum increase 60%) in 2001 and 2002 for both species and annual PAR capture was well correlated with ANPP (mean r2 = 0.77). A decreasing trend in epsilon was observed in non-irrigated stands for sweetgum in 2001 and for sycamore in both years, although this was only significant for sycamore in 2002. Irrigated stands maintained higher gas exchange rates than non-irrigated stands for sweetgum in 2001 and for sycamore in both years, although foliar [N] and Psileaf were generally unaffected. Because Ci decreased in proportion to gs in non-irrigated stands, it appeared that greater stomatal limitation of photosynthesis was associated with decreased Asat. On several measurement dates for sweetgum in 2001 and for sycamore in both years, epsilon was positively correlated with gas exchange variables (Asat, gs, Ci) (r ranged from 0.600 to 0.857). These results indicate that PAR capture is well correlated with ANPP and that gas exchange rates modified by irrigation can influence the conversion of captured light energy to biomass.

  15. Comparison of leaf color chart observations with digital photographs and spectral measurements for estimating maize leaf chlorophyll content

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop nitrogen management is important world-wide, as much for small fields as it is for large operations. Developed as a non-destructive aid for estimating nitrogen content in rice crops, leaf color charts (LCC) are a numbered series of plastic panels that range from yellowgreen to dark green. By vi...

  16. Trait-based community assembly of understory palms along a soil nutrient gradient in a lower montane tropical forest.

    PubMed

    Andersen, Kelly M; Endara, Maria Jose; Turner, Benjamin L; Dalling, James W

    2012-02-01

    Two opposing niche processes have been shown to shape the relationship between ecological traits and species distribution patterns: habitat filtering and competitive exclusion. Habitat filtering is expected to select for similar traits among coexisting species that share similar habitat conditions, whereas competitive exclusion is expected to limit the ecological similarity of coexisting species leading to trait differentiation. Here, we explore how functional traits vary among 19 understory palm species that differ in their distribution across a gradient of soil resource availability in lower montane forest in western Panama. We found evidence that habitat filtering influences species distribution patterns and shifts community-wide and intraspecific trait values. Differences in trait values among sites were more strongly related to soil nutrient availability than to variation in light or rainfall. Soil nutrient availability explained a significant amount of variation in site mean trait values for 4 of 15 functional traits. Site mean values of leaf nitrogen and phosphorus increased 37 and 64%, respectively, leaf carbon:nitrogen decreased 38%, and specific leaf area increased 29% with increasing soil nutrient availability. For Geonoma cuneata, the only species occurring at all sites, leaf phosphorus increased 34% and nitrogen:phosphorus decreased 42% with increasing soil nutrients. In addition to among-site variation, most morphological and leaf nutrient traits differed among coexisting species within sites, suggesting these traits may be important for niche differentiation. Hence, a combination of habitat filtering due to turnover in species composition and intraspecific variation along a soil nutrient gradient and site-specific niche differentiation among co-occurring species influences understory palm community structure in this lower montane forest.

  17. Rhizofiltration of lead using an aromatic medicinal plant Plectranthus amboinicus cultured in a hydroponic nutrient film technique (NFT) system.

    PubMed

    Ignatius, A; Arunbabu, V; Neethu, J; Ramasamy, E V

    2014-11-01

    Heavy metal contamination of water bodies and groundwater is a major concern of the modern world. Rhizofiltration--the use of plant root system to remove/extract pollutants from wastewater--has proven advantages over conventional methods of treatment. However, commercialization of this in situ remediation technology requires a better understanding of plant-metal interactions especially on the ability of different plant species to accumulate metals at different parts of the plant system which is critical for the successful remediation of contaminated medium. Many aquatic and terrestrial plants have been reported to accumulate heavy metals when grown hydroponically. Therefore, a batch experiment with different concentrations of lead and a nutrient film technique (NFT) experiment with recycling of wastewater were employed in this study in order to investigate the rhizofiltration of lead-containing wastewater using Plectranthus amboinicus, an aromatic medicinal plant. Results show that P. amboinicus is tolerant to a wide range of lead concentrations and nutrient deficiency. The plant accumulates considerable amount of lead, particularly in the roots, and translocation to the stem and leaf was limited, indicating that the use of leaves/above-ground parts of the plant for medicinal purposes is not hindered by its ability to remove lead from the soil or water. The study also suggests that the plant can be considered for the clean-up of lead-contaminated wastewater in combination with safe biomass disposal alternatives. PMID:24994103

  18. Rhizofiltration of lead using an aromatic medicinal plant Plectranthus amboinicus cultured in a hydroponic nutrient film technique (NFT) system.

    PubMed

    Ignatius, A; Arunbabu, V; Neethu, J; Ramasamy, E V

    2014-11-01

    Heavy metal contamination of water bodies and groundwater is a major concern of the modern world. Rhizofiltration--the use of plant root system to remove/extract pollutants from wastewater--has proven advantages over conventional methods of treatment. However, commercialization of this in situ remediation technology requires a better understanding of plant-metal interactions especially on the ability of different plant species to accumulate metals at different parts of the plant system which is critical for the successful remediation of contaminated medium. Many aquatic and terrestrial plants have been reported to accumulate heavy metals when grown hydroponically. Therefore, a batch experiment with different concentrations of lead and a nutrient film technique (NFT) experiment with recycling of wastewater were employed in this study in order to investigate the rhizofiltration of lead-containing wastewater using Plectranthus amboinicus, an aromatic medicinal plant. Results show that P. amboinicus is tolerant to a wide range of lead concentrations and nutrient deficiency. The plant accumulates considerable amount of lead, particularly in the roots, and translocation to the stem and leaf was limited, indicating that the use of leaves/above-ground parts of the plant for medicinal purposes is not hindered by its ability to remove lead from the soil or water. The study also suggests that the plant can be considered for the clean-up of lead-contaminated wastewater in combination with safe biomass disposal alternatives.

  19. Impact of carbon dioxide enrichment on the responses of maize leaf transcripts and metabolites to water stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize (Zea mays L.) was grown in controlled environment chambers with ambient (38 Pa) and elevated (70 Pa) CO2. Drought treatments were imposed 17 days after sowing by withholding nutrient solution from one half the plants in each CO2 treatment. Decreases of total leaf water potential, net CO2 ass...

  20. Litterfall dynamics and nutrient deposition at different elevation and land use levels on Mt. Kilimanjaro, Tanzania

    NASA Astrophysics Data System (ADS)

    Becker, Joscha; Pabst, Holger; Mnyonga, James; Kuzyakov, Yakov

    2014-05-01

    One of the major pathways that connect above- and belowground nutrient and carbon stocks in forest ecosystems is litterfall. Depending on climate, tree species composition and stand structure it varies considerably between different ecosystems. Another driving factor that is known to affect ecosystem cycles is the level of anthropogenic disturbance such as land use. In case of tropical regions this is often present as the transformation from rainforests to plantation economy and sustainable agroforestry. The objective of this study was to quantify and determine patterns of carbon and nutrient deposition via tree litterfall in natural and anthropogenically affected forest ecosystems along an elevation gradient of Mt. Kilimanjaro. Tree litter of three natural (lower montane forest), two sustainably used (home gardens) and one intensively managed (shaded coffee plantation) ecosystem was collected on a biweekly basis from May 2012 to July 2013. Samples were separated into leaves, branches and remaining residues, dried and weighted. Carbon and nutrient content were measured in leave samples. We found that the overall annual pattern of litterfall was closely related to rainfall exhibiting a large peak during the dry season. Albeit visible on all plots, this characteristic decreased with elevation. No consistent patterns were found for other components than leaves. Total annual litter mainly consisted of leaf litter and ranges from 4639 kg/ha to 10673 kg/ha for all vegetation types. Flowers, fruits, etc. make up roughly 20% of total litter. Highest and lowest values occurred at home gardens and could not be significantly related to land use or elevation levels. Chemistry though differed between natural and used forest plots. N, P and K contents increased significantly with usage intensity while Mn decreased and C is more or less unaffected. We conclude that on the southern slope of Mt. Kilimanjaro, short term variations in litterfall are related to seasonal climatic

  1. Effect of Surface-Active Pseudomonas spp. on Leaf Wettability

    PubMed Central

    Bunster, Lillian; Fokkema, Nyckle J.; Schippers, Bob

    1989-01-01

    Different strains of Pseudomonas putida and P. fluorescens isolated from the rhizosphere and phyllosphere were tested for surface activity in droplet cultures on polystyrene. Droplets of 6 of the 12 wild types tested spread over the surface during incubation, and these strains were considered surface active; strains not showing this reaction were considered non-surface active. Similar reactions were observed on pieces of wheat leaves. Supernatants from centrifuged broth cultures behaved like droplets of suspensions in broth; exposure to 100°C destroyed the activity. Average contact angles of the supernatants of surface-active and non-surface-active strains on polystyrene were 24° and 72°, respectively. The minimal surface tension of supernatants of the surface-active strains was about 46 mN/m, whereas that of the non-surface-active strains was 64 mN/m (estimations from Zisman plots). After 6 days of incubation, wheat flag leaves sprayed with a dilute suspension of a surface-active strain of P. putida (WCS 358RR) showed a significant increase in leaf wettability, which was determined by contact angle measurements. Increasing the initial concentration of bacteria and the amount of nutrients in the inoculum sprayed on leaves reduced the contact angles from 138° on leaves treated with antibiotics (control) to 43° on leaves treated with surface-active bacteria. A closely related strain with no surface activity on polystyrene did not affect leaf wettability, although it was present in densities similar to those of the surface-active strain. Nutrients alone could occasionally also increase leaf wettability, apparently by stimulating naturally occurring surface-active bacteria. When estimating densities of Pseudomonas spp. underneath droplets with low contact angles, it appeared that populations on leaves treated with a surface-active strain could vary from about 104 to 106 CFU cm−2, suggesting that the surface effect may be prolonged after a decline of the

  2. Nutrient Removal in Wastewater Treatment

    ERIC Educational Resources Information Center

    Shah, Kanti L.

    1973-01-01

    Discusses the sources and effects of nutrients in wastewater, and the methods of their removal in wastewater treatment. In order to conserve water resources and eliminate the cost of nutrient removal, treated effluent should be used wherever possible for irrigation, since it contains all the ingredients for proper plant growth. (JR)

  3. Nutrient Needs of Young Athletes.

    ERIC Educational Resources Information Center

    Willenberg, Barbara; Hemmelgarn, Melinda

    1991-01-01

    Explains the nutritional requirements of children and adolescents, and the physiological roles of the major nutrients. Details the nutrient needs of young athletes, including pre- and postgame meals and fluid replacement. Discusses eating disorders and obesity. Advocates a diet rich in complex carbohydrates. (BC)

  4. Growth, biomass, carbon storage and nutrient distribution in Gmelina arborea Roxb. stands on red lateritic soils in central India.

    PubMed

    Swamy, S L; Puri, S; Singh, A K

    2003-11-01

    Growth, biomass, carbon storage and nutrient (N, P and K) variations in 1 to 6-year-old chronosequence plantations of Gmelina arborea were studied in three degraded red lateritic sites in central India. Growth parameters (dbh, total height and number of branches) varied significantly due to difference in age and site quality, but tree density showed non-significant variation. Stand biomass ranged from 3.94 (1-year-old) to 53.67 Mgha(-1) (6-year-old) and stand carbon in 6-year-old plantations ranged from 24.12 to 31.12 Mgha(-1) at different sites. Among the tree components, the stem wood accounted for maximum C (56.25% at site 1) followed by branches (19.8% at site 3), roots (18.51% at site 2) and foliage (7.01% at site 3). Mean annual C accretion at 6 years age of plantation was highest in site 3 and it was 0.35, 2.66, 0.965 and 0.87 Mgha(-1) for leaf, stem, branches and roots, respectively. Quantity of nutrients increased with age. Total nitrogen accumulation in 6-year-old stands at the three sites ranged from 212.9 to 279.5 kgha(-1) with a mean annual storage of 238.43 kgha(-1) and total K ranged from 170.8 to 220.5 kgha(-1) with a mean annual storage of 189.93 kgha(-1). Phosphorous accumulation was lowest with a mean storage of 16.75 kgha(-1). The organic carbon and nutrients in the soils improved significantly after 6 years of G. arborea planting. Soil organic carbon increased from 8.46 to 14.02 Mgha(-1) within 6 years. At soil depths 0-20 cm, 21-40 cm and 41-60 cm, available N enhanced by 14.85%, 11.98% and 11.25%, K by 10%, 9.13% and 10.63%, whereas phosphorous declined by 26%, 23% and 20%, respectively. At 6 years, G. arborea stands sequestered 31.37 Mgha(-1) carbon. The nutrient management strategies in relation to carbon accretion in G. arborea stands on degraded lateritic sites are discussed. PMID:12895553

  5. Recapturing nutrients from dairy waste using biochar

    NASA Astrophysics Data System (ADS)

    Sarkhot, D.; Ghezzehei, T. A.; Berhe, A. A.

    2009-12-01

    Biochar or biomass derived black carbon is known to be highly resistant to decomposition with half-life periods ranging from hundreds of years to millennia. It is also reported to enhance soil productivity due to high nutrient retention and favorable effects on soil pH, water retention capacity as well as microbial population. Brazilian Terra Preta soils have shown the potential of biochar for long-term carbon sequestration capacity and productivity of soil and many researchers have now focused on utilizing this phenomenon to create fertile, carbon-rich soils, called Terra Preta Nova. Although the highly adsorptive nature of biochar is well characterized, the potential for using biochar in environmental cleanup efforts is relatively unexplored. Dairy waste is a source of significant water pollution because it introduces excess nutrients such as phosphates and nitrates into the soil and water system. Since many soils have limited capacity to retain nitrate and phosphate, especially for long periods of time, the utility of dairy waste manure to enhance soil fertility and nutrient availability to plants is limited. Here, we present results from a project that we started to determine the potential of biochar to recover the excess nutrients from dairy flushed manure. In this initial study, a commercially available biochar amendment was ground and used in a batch sorption experiment with the dairy flushed manure from a local dairy in Merced, California. Four manure dilutions viz. 10, 25, 50 and 100%, and three shaking times, viz. 1, 12 and 24 hours were used for this study. We then calculated the amount of ammonia, nitrate and phosphate adsorbed by the biochar using differences in nutrient concentrations before and after the sorption experiment. Biochar showed significant capacity of adsorbing these nutrients, suggesting a potential for controlling the dairy pollution. The resulting enriched biochar can potentially act as a slow release fertilizer and enhance soil

  6. Nutrient levels within leaves, stems, and roots of the xeric species Reaumuria soongorica in relation to geographical, climatic, and soil conditions

    PubMed Central

    He, Mingzhu; Zhang, Ke; Tan, Huijuan; Hu, Rui; Su, Jieqiong; Wang, Jin; Huang, Lei; Zhang, Yafeng; Li, Xinrong

    2015-01-01

    Besides water relations, nutrient allocation, and stoichiometric traits are fundamental feature of shrubs. Knowledge concerning the nutrient stoichiometry of xerophytes is essential to predicting the biogeochemical cycling in desert ecosystems as well as to understanding the homoeostasis and variability of nutrient traits in desert plants. Here, we focused on the temperate desert species Reaumuria soongorica and collected samples from plant organs and soil over 28 different locations that covered a wide distributional gradient of this species. Carbon (C), nitrogen (N), and phosphorus (P) concentrations and their stoichiometry were determined and subsequently compared with geographic, climatic, and edaphic factors. The mean leaf C, N, and P concentrations and C/N, C/P, and N/P ratios were 371.6 mg g−1, 10.6 mg g−1, 0.73 mg g−1, and 59.7, 837.9, 15.7, respectively. Stem and root C concentrations were higher than leaf C, while leaf N was higher than stem and root N. Phosphorus concentration and N/P did not differ among plant organs. Significant differences were found between root C/N and leaf C/N as well as between root C/P and leaf C/P. Leaf nutrient traits respond to geographic and climatic factors, while nutrient concentrations of stems and roots are mostly affected by soil P and pH. We show that stoichiometric patterns in different plant organs had different responses to environmental variables. Studies of species-specific nutrient stoichiometry can help clarify plant–environment relationships and nutrient cycling patterns in desert ecosystems. PMID:25897388

  7. Physical Limits to Leaf Size in Tall Trees

    NASA Astrophysics Data System (ADS)

    Jensen, Kaare H.; Zwieniecki, Maciej A.

    2013-01-01

    Leaf sizes in angiosperm trees vary by more than 3 orders of magnitude, from a few mm to over 1 m. This large morphological freedom is, however, only expressed in small trees, and the observed leaf size range declines with tree height, forming well-defined upper and lower boundaries. The vascular system of tall trees that distributes the products of photosynthesis connects distal parts of the plant and forms one of the largest known continuous microfluidic distribution networks. In biological systems, intrinsic properties of vascular systems are known to constrain the morphological freedom of the organism. We show that the limits to leaf size can be understood by physical constraints imposed by intrinsic properties of the carbohydrate transport network. The lower boundary is set by a minimum energy flux, and the upper boundary is set by a diminishing gain in transport efficiency.

  8. Global patterns in leaf 13C discrimination and implications for studies of past and future climate.

    PubMed

    Diefendorf, Aaron F; Mueller, Kevin E; Wing, Scott L; Koch, Paul L; Freeman, Katherine H

    2010-03-30

    Fractionation of carbon isotopes by plants during CO(2) uptake and fixation (Delta(leaf)) varies with environmental conditions, but quantitative patterns of Delta(leaf) across environmental gradients at the global scale are lacking. This impedes interpretation of variability in ancient terrestrial organic matter, which encodes climatic and ecological signals. To address this problem, we converted 3,310 published leaf delta(13)C values into mean Delta(leaf) values for 334 woody plant species at 105 locations (yielding 570 species-site combinations) representing a wide range of environmental conditions. Our analyses reveal a strong positive correlation between Delta(leaf) and mean annual precipitation (MAP; R(2) = 0.55), mirroring global trends in gross primary production and indicating stomatal constraints on leaf gas-exchange, mediated by water supply, are the dominant control of Delta(leaf) at large spatial scales. Independent of MAP, we show a lesser, negative effect of altitude on Delta(leaf) and minor effects of temperature and latitude. After accounting for these factors, mean Delta(leaf) of evergreen gymnosperms is lower (by 1-2.7 per thousand) than for other woody plant functional types (PFT), likely due to greater leaf-level water-use efficiency. Together, environmental and PFT effects contribute to differences in mean Delta(leaf) of up to 6 per thousand between biomes. Coupling geologic indicators of ancient precipitation and PFT (or biome) with modern Delta(leaf) patterns has potential to yield more robust reconstructions of atmospheric delta(13)C values, leading to better constraints on past greenhouse-gas perturbations. Accordingly, we estimate a 4.6 per thousand decline in the delta(13)C of atmospheric CO(2) at the onset of the Paleocene-Eocene Thermal Maximum, an abrupt global warming event approximately 55.8 Ma. PMID:20231481

  9. Effects of Leaf Litter Species Diversity on Decomposition in a Forested Watershed in the Southern Appalachians, USA

    NASA Astrophysics Data System (ADS)

    Kominoski, J. S.; Ball, B. A.; Pringle, C. M.; Hunter, M. D.; Coleman, D. C.

    2005-05-01

    Decomposition of leaf litter influences nutrient cycling and energy flow in terrestrial and aquatic ecosystems. Diversity of decomposing leaves in streams is a function of riparian plant composition and temporal and spatial heterogeneity. Leaf species have different decay rates, and leaf litter input to streams varies seasonally. Leaves with decreased lignin, lower phenolics, and lower C:N:P typically exhibit faster rates of decay and are more bioaccessible. Our collaborative project at Coweeta Hydrologic Laboratory, North Carolina, compares leaf litter decomposition in a stream and riparian zone. We selected four leaf litter species representing a gradient of resource qualities and decay rates to develop a 2 x 2 factorial design with 15 species combinations. We examined effects of species diversity and time on leaf litter decay rate (k), phytochemistry, and microbial and macroinvertebrate colonization. Results for in-stream leaf litter indicate a positive, non-additive effect of species diversity on k. AFDM remaining of mixed and single species packs was unpredictable. Defense (e.g., phenolics) and structural (e.g., fiber) compounds varied in single and mixed species packs throughout decay; however, leaf packs with Rhododendron maximum had significantly less associated fungal biomass than all other single and mixed species packs (p < .0001).

  10. Nutrient fluxes from insect herbivory increase during ecosystem retrogression in boreal forest.

    PubMed

    Metcalfe, Daniel B; Crutsinger, Gregory M; Kumordzi, Bright B; Wardle, David A

    2016-01-01

    Ecological theory, developed largely from ungulates and grassland systems, predicts that herbivory accelerates nutrient cycling more in productive than unproductive systems. This prediction may be important for understanding patterns of ecosystem change over time and space, but its applicability to other ecosystems and types of herbivore remain uncertain. We estimated fluxes of nitrogen (N) and phosphorus (P) from herbivory of a common tree species (Betula pubescens) by a common species of herbivorous insect along a -5000-yr boreal chronosequence. Contrary to established theory, fluxes of N and P via herbivory increased along the chronosequence despite a decline in plant productivity. The herbivore-mediated N and P fluxes to the soil are comparable to the main alternative pathway for these nutrients via tree leaf litterfall. We conclude that insect herbivores can make large contributions to nutrient cycling even in unproductive systems, and influence the rate and pattern of ecosystem development, particularly in systems with low external nutrient inputs.

  11. Nutrient fluxes from insect herbivory increase during ecosystem retrogression in boreal forest.

    PubMed

    Metcalfe, Daniel B; Crutsinger, Gregory M; Kumordzi, Bright B; Wardle, David A

    2016-01-01

    Ecological theory, developed largely from ungulates and grassland systems, predicts that herbivory accelerates nutrient cycling more in productive than unproductive systems. This prediction may be important for understanding patterns of ecosystem change over time and space, but its applicability to other ecosystems and types of herbivore remain uncertain. We estimated fluxes of nitrogen (N) and phosphorus (P) from herbivory of a common tree species (Betula pubescens) by a common species of herbivorous insect along a -5000-yr boreal chronosequence. Contrary to established theory, fluxes of N and P via herbivory increased along the chronosequence despite a decline in plant productivity. The herbivore-mediated N and P fluxes to the soil are comparable to the main alternative pathway for these nutrients via tree leaf litterfall. We conclude that insect herbivores can make large contributions to nutrient cycling even in unproductive systems, and influence the rate and pattern of ecosystem development, particularly in systems with low external nutrient inputs. PMID:27008782

  12. Modulatory role of mineral nutrients on cadmium accumulation and stress tolerance in Oryza sativa L. seedlings.

    PubMed

    Sebastian, Abin; Prasad, M N V

    2016-01-01

    Cadmium (Cd)-contaminated rice is a serious health concern. In the present study, Cd accumulation and stress responses in Oryza sativa L. cv MTU 7029 seedlings were characterized under varying concentrations of plant nutrients in Hoagland media. It has been found that nutrient supplement modulates Cd accumulation and related stress tolerance while efficacy of each nutrient varies. Supplementation of Fe, Mn, N, Ca, and S were found to reduce Cd accumulation in leaf whereas Mn and Fe supply effect was also observed in roots. Analysis of maximum quantum efficiency of photosynthesis indicated that Fe and S supplements confer highest Cd stress tolerance. The present study highlighted the potential of plant nutrients for minimizing Cd accumulation and its toxicity in rice seedlings.

  13. Continental-scale effects of nutrient pollution on stream ecosystem functioning.

    PubMed

    Woodward, Guy; Gessner, Mark O; Giller, Paul S; Gulis, Vladislav; Hladyz, Sally; Lecerf, Antoine; Malmqvist, Björn; McKie, Brendan G; Tiegs, Scott D; Cariss, Helen; Dobson, Mike; Elosegi, Arturo; Ferreira, Verónica; Graça, Manuel A S; Fleituch, Tadeusz; Lacoursière, Jean O; Nistorescu, Marius; Pozo, Jesús; Risnoveanu, Geta; Schindler, Markus; Vadineanu, Angheluta; Vought, Lena B-M; Chauvet, Eric

    2012-06-15

    Excessive nutrient loading is a major threat to aquatic ecosystems worldwide that leads to profound changes in aquatic biodiversity and biogeochemical processes. Systematic quantitative assessment of functional ecosystem measures for river networks is, however, lacking, especially at continental scales. Here, we narrow this gap by means of a pan-European field experiment on a fundamental ecosystem process--leaf-litter breakdown--in 100 streams across a greater than 1000-fold nutrient gradient. Dramatically slowed breakdown at both extremes of the gradient indicated strong nutrient limitation in unaffected systems, potential for strong stimulation in moderately altered systems, and inhibition in highly polluted streams. This large-scale response pattern emphasizes the need to complement established structural approaches (such as water chemistry, hydrogeomorphology, and biological diversity metrics) with functional measures (such as litter-breakdown rate, whole-system metabolism, and nutrient spiraling) for assessing ecosystem health.

  14. Integrating transcriptomic and metabolomic analysis to understand natural leaf senescence in sunflower.

    PubMed

    Moschen, Sebastián; Bengoa Luoni, Sofía; Di Rienzo, Julio A; Caro, María Del Pilar; Tohge, Takayuki; Watanabe, Mutsumi; Hollmann, Julien; González, Sergio; Rivarola, Máximo; García-García, Francisco; Dopazo, Joaquin; Hopp, Horacio Esteban; Hoefgen, Rainer; Fernie, Alisdair R; Paniego, Norma; Fernández, Paula; Heinz, Ruth A

    2016-02-01

    Leaf senescence is a complex process, which has dramatic consequences on crop yield. In sunflower, gap between potential and actual yields reveals the economic impact of senescence. Indeed, sunflower plants are incapable of maintaining their green leaf area over sustained periods. This study characterizes the leaf senescence process in sunflower through a systems biology approach integrating transcriptomic and metabolomic analyses: plants being grown under both glasshouse and field conditions. Our results revealed a correspondence between profile changes detected at the molecular, biochemical and physiological level throughout the progression of leaf senescence measured at different plant developmental stages. Early metabolic changes were detected prior to anthesis and before the onset of the first senescence symptoms, with more pronounced changes observed when physiological and molecular variables were assessed under field conditions. During leaf development, photosynthetic activity and cell growth processes decreased, whereas sucrose, fatty acid, nucleotide and amino acid metabolisms increased. Pathways related to nutrient recycling processes were also up-regulated. Members of the NAC, AP2-EREBP, HB, bZIP and MYB transcription factor families showed high expression levels, and their expression level was highly correlated, suggesting their involvement in sunflower senescence. The results of this study thus contribute to the elucidation of the molecular mechanisms involved in the onset and progression of leaf senescence in sunflower leaves as well as to the identification of candidate genes involved in this process.

  15. Nitrogen and Photosynthesis in the Flag Leaf of Wheat (Triticum aestivum L.).

    PubMed

    Evans, J R

    1983-06-01

    Wheat (Triticum aestivum L. cv Yecora 70) plants were grown with various concentrations of nitrate nitrogen available to the roots. Sampling of flag leaves began after they had reached full expansion and continued throughout senescence. Rates of gas exchange, ribulose-1,5-bisphosphate (RuP(2)) carboxylase activity, and the amounts of chlorophyll, soluble protein, nitrogen, and phosphorus were determined for each flag leaf. Rate of CO(2) assimilation was uniquely related to total leaf nitrogen irrespective of nutrient treatment, season, and leaf age. Assimilation rate increased with leaf nitrogen, but the slope of the relationship declined markedly when leaf nitrogen exceeded 125 millimoles nitrogen per square meter. Chlorophyll content and RuP(2) carboxylase activity were approximately proportional to leaf nitrogen content. As leaves aged, RuP(2) carboxylase activity and calculated Hill activity declined in parallel. With normal ambient partial pressure of CO(2), the intercellular partial pressure of CO(2) was always such that rate of assimilation appeared colimited by RuP(2) carboxylation and RuP(2) regeneration capacity.The initial slope of rate of CO(2) assimilation against intercellular partial pressure of CO(2) varied nonlinearly with carboxylase activity. It is suggested that this was due to a finite conductance to CO(2) diffusion in the wall and liquid phase which causes a drop in CO(2) partial pressure between the intercellular spaces and the site of carboxylation. A double reciprocal plot was used to obtain an estimate of the transfer conductance.

  16. Extending the generality of leaf economic design principles in the cycads, an ancient lineage.

    PubMed

    Zhang, Yong-Jiang; Cao, Kun-Fang; Sack, Lawren; Li, Nan; Wei, Xue-Mei; Goldstein, Guillermo

    2015-04-01

    Cycads are the most ancient lineage of living seed plants, but the design of their leaves has received little study. We tested whether cycad leaves are governed by the same fundamental design principles previously established for ferns, conifers and angiosperms, and characterized the uniqueness of this relict lineage in foliar trait relationships. Leaf structure, photosynthesis, hydraulics and nutrient composition were studied in 33 cycad species from nine genera and three families growing in two botanical gardens. Cycads varied greatly in leaf structure and physiology. Similarly to other lineages, light-saturated photosynthetic rate per mass (Am ) was related negatively to leaf mass per area and positively to foliar concentrations of chlorophyll, nitrogen (N), phosphorus and iron, but unlike angiosperms, leaf photosynthetic rate was not associated with leaf hydraulic conductance. Cycads had lower photosynthetic N use efficiency and higher photosynthetic performance relative to hydraulic capacity compared with other lineages. These findings extend the relationships shown for foliar traits in angiosperms to the cycads. This functional convergence supports the modern synthetic understanding of leaf design, with common constraints operating across lineages, even as they highlight exceptional aspects of the biology of this key relict lineage. PMID:25622799

  17. Extending the generality of leaf economic design principles in the cycads, an ancient lineage.

    PubMed

    Zhang, Yong-Jiang; Cao, Kun-Fang; Sack, Lawren; Li, Nan; Wei, Xue-Mei; Goldstein, Guillermo

    2015-04-01

    Cycads are the most ancient lineage of living seed plants, but the design of their leaves has received little study. We tested whether cycad leaves are governed by the same fundamental design principles previously established for ferns, conifers and angiosperms, and characterized the uniqueness of this relict lineage in foliar trait relationships. Leaf structure, photosynthesis, hydraulics and nutrient composition were studied in 33 cycad species from nine genera and three families growing in two botanical gardens. Cycads varied greatly in leaf structure and physiology. Similarly to other lineages, light-saturated photosynthetic rate per mass (Am ) was related negatively to leaf mass per area and positively to foliar concentrations of chlorophyll, nitrogen (N), phosphorus and iron, but unlike angiosperms, leaf photosynthetic rate was not associated with leaf hydraulic conductance. Cycads had lower photosynthetic N use efficiency and higher photosynthetic performance relative to hydraulic capacity compared with other lineages. These findings extend the relationships shown for foliar traits in angiosperms to the cycads. This functional convergence supports the modern synthetic understanding of leaf design, with common constraints operating across lineages, even as they highlight exceptional aspects of the biology of this key relict lineage.

  18. Leaf water oxygen isotope measurement by direct equilibration.

    PubMed

    Song, Xin; Barbour, Margaret M

    2016-08-01

    The oxygen isotope composition of leaf water imparts a signal to a range of molecules in the atmosphere and biosphere, but has been notoriously difficult to measure in studies requiring a large number of samples as a consequence of the labour-intensive extraction step. We tested a method of direct equilibration of water in fresh leaf samples with CO2 , and subsequent oxygen isotope analysis on an optical spectrometer. The oxygen isotope composition of leaf water measured by the direct equilibration technique was strongly linearly related to that of cryogenically extracted leaf water in paired samples for a wide range of species with differing anatomy, with an R(2) of 0.95. The somewhat more enriched values produced by the direct equilibration method may reflect lack of full equilibration with unenriched water in the vascular bundles, but the strong relationship across a wide range of species suggests that this difference can be adequately corrected for using a simple linear relationship. PMID:27147584

  19. Use of Select Nutrients to Foster Wellness.

    ERIC Educational Resources Information Center

    Cassel, Russell N.

    1987-01-01

    Discusses how to be healthy through one's diet. Lists 20 nutrients necessary for one's well being and explains role of each nutrient. Describes how nutrients complement one another and asserts that the right combination of nutrients can sometimes substitute for medication. Also lists 20 diagnostic categories of problems and suggests nutrients to…

  20. Effects of fungal inocula and habitat conditions on alder and eucalyptus leaf litter decomposition in streams of northern Spain.

    PubMed

    Pérez, Javier; Galán, Javier; Descals, Enrique; Pozo, Jesús

    2014-02-01

    We investigated how fungal decomposer (aquatic hyphomycetes) communities colonizing alder and eucalyptus leaf litter respond to changes in habitat characteristics (transplantation experiment). We examined the breakdown of leaf materials and the associated fungal communities at two contrasting sites, a headwater stream (H) and a midreach (M). Agroforestry increased from headwater to midreach. One month after the start of experiments at both sites, some leaf samples from the midreach site were transplanted to the headwater site (M-H treatment). Although both sites showed similar dissolved inorganic nutrient concentrations, eucalyptus leaves initially incubated at the midreach site (M, M-H) increased their breakdown rate compared to those incubated along the experiment at the headwater site (H). Alder breakdown rate was not enhanced, suggesting that their consumption was not limited by nutrient availability. Sporulation rates clearly differed between leaf types (alder > eucalyptus) and streams (H > M), but no transplantation effect was detected. When comparing conidial assemblages after transplantation, an inoculum effect (persistence of early colonizing species) was clear in both leaf species. Substrate preference and shifts in the relative importance of some fungal species along the process were also observed. Overall, our results support the determining role of the initial conditioning phase on the whole litter breakdown process, highlighting the importance of intrinsic leaf characteristics and those of the incubation habitat.

  1. Estimation of leaf nitrogen and silicon using hyperspectral remote sensing

    NASA Astrophysics Data System (ADS)

    Mokhele, Tholang A.; Ahmed, Fethi B.

    2010-11-01

    The potential to estimate the nutrient status in important agricultural crops such as maize and sugarcane is of significant interest. In South African sugarcane agriculture, just like in global ecosystem, the estimation of Nitrogen (N) and Silicon (Si) is very important. These nutrients are one of the factors influencing the prevalence of the stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae). Therefore, the researchers aim at estimating leaf N and Si concentration as well as their ratio in sugarcane using hyperspectral remote sensing (spectroradiometry) for monitoring E. saccharina. A hand-held Analytical Spectral Devices (ASD) Field Spec® 3 spectroradiometer was used to take leaf spectral measurements of sugarcane plants from a potted-plant trial taking place under shade house conditions. In this trial, nitrogen and silicon nutrient applications as well as varieties used were known. In addition, watering regimes and artificial infestation of E. saccharina were carefully controlled. The study results indicate that the Red-edge Index (R740/R720) is linearly related to N concentration (R2 = 0.81, Root Mean Square Error (RMSE) = 0.103) for N37 with the highest correlation coefficient. For Si, the index (R750-R560)/(R750+R560) was linearly related to Si concentration (R2 = 0.53, RMSE = 0.118) for N25. Finally, the N:Si ratio was linearly correlated to the index (R1075-R730)/(R1075+R730) (R2 = 0.67, RMSE = 1.508) for N37, hence this index can be used for early detection of E. saccharina damage or for identifying sugarcane that is prone to attack by E. saccharina. It was concluded that hyperspectral remote sensing has potential for use in estimating the N:Si ratio and E. saccharina potential infestations can be monitored rapidly and nondestructively in sugarcane under controlled conditions. It is recommended that an advanced study be conducted in field conditions using airborne and/or spaceborne hyperspectral sensors.

  2. Grass leaf silicification: Natural selection for an inducible defense against herbivores.

    PubMed

    McNaughton, S J; Tarrants, J L

    1983-02-01

    Plants from four populations of three species of African grasses were collected from grasslands in Tanzania's Serengeti National Park that differ in the grazing intensity that they experience. Plants were grown in the laboratory in a factorial experiment in which variables were plant origin, species identification of plants, defoliation intensity, and supply of soluble silicate in the nutrient medium. All plants accumulated silica in leaf blades in the absence of soluble silicate from the nutrient medium. Plants native to the more heavily grazed grassland accumulated more silica in their leaf blades than did plants from the less heavily grazed site. Blade silica content was higher when plants were defoliated, indicating that silicification is an inducible defense against herbivores. The quantitative heterogeneity of this qualitatively homogeneous plant defense system may have contributed to the evolution of high species diversity in the grazing fauna.

  3. Grass leaf silicification: Natural selection for an inducible defense against herbivores

    PubMed Central

    McNaughton, S. J.; Tarrants, J. L.

    1983-01-01

    Plants from four populations of three species of African grasses were collected from grasslands in Tanzania's Serengeti National Park that differ in the grazing intensity that they experience. Plants were grown in the laboratory in a factorial experiment in which variables were plant origin, species identification of plants, defoliation intensity, and supply of soluble silicate in the nutrient medium. All plants accumulated silica in leaf blades in the absence of soluble silicate from the nutrient medium. Plants native to the more heavily grazed grassland accumulated more silica in their leaf blades than did plants from the less heavily grazed site. Blade silica content was higher when plants were defoliated, indicating that silicification is an inducible defense against herbivores. The quantitative heterogeneity of this qualitatively homogeneous plant defense system may have contributed to the evolution of high species diversity in the grazing fauna. PMID:16578767

  4. Plant herbivory responses through changes in leaf quality have no effect on subsequent leaf-litter decomposition in a neotropical rain forest tree community.

    PubMed

    Cárdenas, Rafael E; Hättenschwiler, Stephan; Valencia, Renato; Argoti, Adriana; Dangles, Olivier

    2015-08-01

    It is commonly accepted that plant responses to foliar herbivory (e.g. plant defenses) can influence subsequent leaf-litter decomposability in soil. While several studies have assessed the herbivory-decomposability relationship among different plant species, experimental tests at the intra-specific level are rare, although critical for a mechanistic understanding of how herbivores affect decomposition and its consequences at the ecosystem scale. Using 17 tree species from the Yasuní National Park, Ecuadorian Amazonia, and applying three different herbivore damage treatments, we experimentally tested whether the plant intra-specific responses to herbivory, through changes in leaf quality, affect subsequent leaf-litter decomposition in soil. We found no effects of herbivore damage on the subsequent decomposition of leaf litter within any of the species tested. Our results suggest that leaf traits affecting herbivory are different from those influencing decomposition. Herbivore damage showed much higher intra-specific than inter-specific variability, while we observed the opposite for decomposition. Our findings support the idea that interactions between consumers and their resources are controlled by different factors for the green and the brown food-webs in tropical forests, where herbivory may not necessarily generate any direct positive or negative feedbacks for nutrient cycling.

  5. The Contribution of Occult Precipitation to Nutrient Deposition on the West Coast of South Africa

    PubMed Central

    2015-01-01

    The Strandveld mediterranean-ecosystem of the west coast of South Africa supports floristically diverse vegetation growing on mostly nutrient-poor aeolian sands and extending from the Atlantic Ocean tens of kilometers inland. The cold Benguela current upwelling interacts with warm onshore southerly winds in summer causing coastal fogs in this region. We hypothesized that fog and other forms of occult precipitation contribute moisture and nutrients to the vegetation. We measured occult precipitation over one year along a transect running inland in the direction of the prevailing wind and compared the nutrient concentrations with those in rainwater. Occult deposition rates of P, N, K, Mg, Ca, Na, Al and Fe all decreased with distance from the ocean. Furthermore, ratios of cations to Na were similar to those of seawater, suggesting a marine origin for these. In contrast, N and P ratios in occult precipitation were higher than in seawater. We speculate that this is due to marine foam contributing to occult precipitation. Nutrient loss in leaf litter from dominant shrub species was measured to indicate nutrient demand. We estimated that occult precipitation could meet the demand of the dominant shrubby species for annual N, P, K and Ca. Of these species, those with small leaves intercepted more moisture and nutrients than those with larger leaves and could take up foliar deposits of glycine, NO3-, NH4+ and Li (as tracer for K) through leaf surfaces. We conclude that occult deposition together with rainfall deposition are potentially important nutrient and moisture sources for the Strandveld vegetation that contribute to this vegetation being floristically distinct from neighbouring nutrient-poor Fynbos vegetation. PMID:26017747

  6. The contribution of occult precipitation to nutrient deposition on the west coast of South Africa.

    PubMed

    Nyaga, Justine M; Neff, Jason C; Cramer, Michael D

    2015-01-01

    The Strandveld mediterranean-ecosystem of the west coast of South Africa supports floristically diverse vegetation growing on mostly nutrient-poor aeolian sands and extending from the Atlantic Ocean tens of kilometers inland. The cold Benguela current upwelling interacts with warm onshore southerly winds in summer causing coastal fogs in this region. We hypothesized that fog and other forms of occult precipitation contribute moisture and nutrients to the vegetation. We measured occult precipitation over one year along a transect running inland in the direction of the prevailing wind and compared the nutrient concentrations with those in rainwater. Occult deposition rates of P, N, K, Mg, Ca, Na, Al and Fe all decreased with distance from the ocean. Furthermore, ratios of cations to Na were similar to those of seawater, suggesting a marine origin for these. In contrast, N and P ratios in occult precipitation were higher than in seawater. We speculate that this is due to marine foam contributing to occult precipitation. Nutrient loss in leaf litter from dominant shrub species was measured to indicate nutrient demand. We estimated that occult precipitation could meet the demand of the dominant shrubby species for annual N, P, K and Ca. Of these species, those with small leaves intercepted more moisture and nutrients than those with larger leaves and could take up foliar deposits of glycine, NO3(-), NH4(+) and Li (as tracer for K) through leaf surfaces. We conclude that occult deposition together with rainfall deposition are potentially important nutrient and moisture sources for the Strandveld vegetation that contribute to this vegetation being floristically distinct from neighbouring nutrient-poor Fynbos vegetation.

  7. Leaf morphophysiology of a Neotropical mistletoe is shaped by seasonal patterns of host leaf phenology.

    PubMed

    Scalon, Marina Corrêa; Rossatto, Davi Rodrigo; Domingos, Fabricius Maia Chaves Bicalho; Franco, Augusto Cesar

    2016-04-01

    Several mistletoe species are able to grow and reproduce on both deciduous and evergreen hosts, suggesting a degree of plasticity in their ability to cope with differences in intrinsic host functions. The aim of this study was to investigate the influence of host phenology on mistletoe water relations and leaf gas exchange. Mistletoe Passovia ovata parasitizing evergreen (Miconia albicans) hosts and P. ovata parasitizing deciduous (Byrsonima verbascifolia) hosts were sampled in a Neotropical savanna. Photosynthetic parameters, diurnal cycles of stomatal conductance, pre-dawn and midday leaf water potential, and stomatal anatomical traits were measured during the peak of the dry and wet seasons, respectively. P. ovata showed distinct water-use strategies that were dependent on host phenology. For P. ovata parasitizing the deciduous host, water use efficiency (WUE; ratio of photosynthetic rate to transpirational water loss) was 2-fold lower in the dry season than in the wet season; in contrast, WUE was maintained at the same level during the wet and dry seasons in P. ovata parasitizing the evergreen host. Generally, mistletoe and host diurnal cycles of stomatal conductance were linked, although there were clear differences in leaf water potential, with mistletoe showing anisohydric behaviour and the host showing isohydric behaviour. Compared to mistletoes attached to evergreen hosts, those parasitizing deciduous hosts had a 1.4-fold lower stomatal density and 1.2-fold wider stomata on both leaf surfaces, suggesting that the latter suffered less intense drought stress. This is the first study to show morphophysiological differences in the same mistletoe species parasitizing hosts of different phenological groups. Our results provide evidence that phenotypical plasticity (anatomical and physiological) might be essential to favour the use of a greater range of hosts. PMID:26686200

  8. Behavior of Leaf Meristems and Their Modification

    PubMed Central

    Ichihashi, Yasunori; Tsukaya, Hirokazu

    2015-01-01

    A major source of diversity in flowering plant form is the extensive variability of leaf shape and size. Leaf formation is initiated by recruitment of a handful of cells flanking the shoot apical meristem (SAM) to develop into a complex three-dimensional structure. Leaf organogenesis depends on activities of several distinct meristems that are established and spatiotemporally differentiated after the initiation of leaf primordia. Here, we review recent findings in the gene regulatory networks that orchestrate leaf meristem activities in a model plant Arabidopsis thaliana. We then discuss recent key studies investigating the natural variation in leaf morphology to understand how the gene regulatory networks modulate leaf meristems to yield a substantial diversity of leaf forms during the course of evolution. PMID:26648955

  9. Spectral reflectance relationships to leaf water stress

    NASA Technical Reports Server (NTRS)

    Ripple, William J.

    1986-01-01

    Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

  10. An Innovative Way to Monitor Leaf Age

    NASA Astrophysics Data System (ADS)

    Garnello, A.; Paredes, K.; Trinh, U.; Saleska, S. R.; Wu, J.

    2013-12-01

    Anthony John Garnello, Karina Paredes, Uyen Khanh Ho Trinh, Jin Wu, Scott Saleska Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA Abstract: Leaf age is an important characteristic for controlling plant functional performance and is associated with the changes of leaf physical, chemical, and physiological properties. Understanding how plant physiology changes over time will allow more accurate predictions of growth patterns, and a more comprehensive understanding of vegetative life histories. There still lacks an efficient technique in monitoring leaf age, tagging leaves is still the only way to accurately monitor leaf age. The goal of this study is to develop a multi-metric, accurate technique for better monitoring of leaf age. In order to acquire true leaf age records, 10 individual plant species were selected at the University of Arizona campus, and newly flushing leaves were tagged and monitored during the Monsoon season (from early June, 2013, to mid October, 2013). Every 2 weeks, 10 to 15 leaves in relative age order were harvested from each 1-meter branch to measure multiple key leaf metrics, including leaf thickness (via micro