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1081篇 您的检索式:作者名="WERNER H"
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1On the combined effect of soil fertility and topography on tree growth in subtropical forest ecosystems—a study from SE China显示文摘Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning(BEF)experiment in subtropical SE China.Methods Geomorphometric terrain analyses were carried out at a spatial resolution of 5×5 m.Soil samples of different depth increments and data on tree height were collected from a total of 566 plots(667 m2 each).The soils were analyzed for carbon(soil organic carbon[SOC]),nitrogen,acidity,cation exchange capacity(CEC),exchangeable cations and base saturation as soil fertility attributes.All plots were classified into geomorphological units.Analyses of variance and linear regressions were applied to all terrain,soil fertility and tree growth attributes.Important Findings In general,young and shallow soils and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment.This explains the concurrently increasing CEC and SOC stocks downslope,in hollows and in valleys.However,colluvial,carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways.The results showed that soil fertility is mainly influenced by topography.Monte-Carlo flow accumulation(MCCA),curvature,slope and aspect significantly affected soil fertility.Furthermore,soil fertility was affected by the different geomorphological positions on the experimental sites with ridge and spur positions showing lower exchangeable base cation contents,especially potassium(K),due to leaching.This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50 cm depth.Few soil fertility attributes affect tree height after 1-2 years of growth,among which C stocks proved to be most important while pH_(KCl)and CEC only played minor roles.Nevertheless,soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1-2 years growth.Hence,our study showed that forest nutrition is coupled to a recycling of litter nutrients,and does not only depend on subsequent supply of nutrients from the mineral soil.Besides soil fertility,topography affected tree height.We found that especially MCCA as indicator of water availability affected tree growth at small-scale,as well as aspect.Overall,our synthesis on the interrelation between fertility,topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions.In this respect,small-scale soil-plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility.In addition,it shows that terrain attributes should be accounted for in ecological research.Thomas Scholten Philipp Goebes Peter Kühn Steffen Seitz Thorsten Assmann Jürgen Bauhus Helge Bruelheide Francois Buscot Alexandra Erfmeier Markus Fischer Werner Härdtle Jin-Sheng He Keping Ma Pascal A.Niklaus Michael Scherer-Lorenzen Bernhard Schmid Xuezheng Shi Zhengshan Song Goddert von Oheimb Christian Wirth Tesfaye Wubet Karsten Schmidt 2017Journal of Plant Ecology2017,10,1:22
2Crown and leaf traits as predictors of subtropical tree sapling growth rates显示文摘Aims Growth rates of plants are driven by factors that influence the amount of resources captured and the efficiency of resource use.In trees,the amount of light captured and the efficiency of light use strongly depends on crown characteristics and leaf traits.Although theory predicts that both crown and leaf traits affect tree growth,few studies have yet to integrate these two types of traits to explain species-specific growth rates.Using 37 broad-leaved tree species of subtropical forests in SE China,we investigated how interspecific differences in wood volume growth rates were affected by crown and leaf traits.We tested the hypotheses that(i)larger crown dimensions promote growth rates,(ii)species-specific growth rates are positively related to leaf stomatal conductance,leaf water potential and leaf chemical components,and negatively related to leaf C/N and leaf toughness and(iii)the two sets of traits better explain growth rates in combination than either alone.Methods Our study was conducted in a large-scale forest Biodiversity and Ecosystem Functioning experiment in China(BEF-China),located in a mountainous region in Jiangxi Province.We related 17 functional traits(two crown dimension and three crown structure traits;six physiological and six morphological leaf traits)to the mean annual growth rate of wood volume of young trees of the studied species.Interrelationships between crown and leaf traits were analyzed using principal component analysis.Simple linear regression analysis was used to test the effect of each trait separately.We used multiple regression analysis to establish the relationship of growth rate to each set of traits(crown traits,physiological and morphological leaf traits)and to the combination of all types of traits.The coefficients of determination(R^(2)_(adj))of the best multiple regression models were compared to determine the relative explanatory power of crown and leaf traits and a combination of both.Important Findings The species-specific growth rates were not related to any of the single crown traits,but were related positively to leaf stomatal conductance and leaf water potential individually,and negatively to leaf toughness,with approximately 13%variance explained by each of the traits.Combinations of different crown traits did not significantly explain the species-specific growth rates,whereas combinations of either physiological or morphological leaf traits explained 24%and 31%,respectively.A combination of both crown and leaf traits explained 42%of variance in species-specific growth rates.We concluded that sets of traits related to carbon assimilation at the leaf-level and to overall amount of leaves exposed at the crown-level jointly explained species-specific growth rates better than either set of traits alone.Ying Li Wenzel Kröber Helge Bruelheide Werner Härdtle Goddert von Oheimb 2017Journal of Plant Ecology2017,10,1:18
3Interspecific and intraspecific variation in specific root length drives aboveground biodiversity effects in young experimental forest stands显示文摘Aims Although the net biodiversity effect(NE)can be statistically partitioned into complementarity and selection effects(CE and SE),there are different underlying mechanisms that can cause a certain partitioning.Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.Methods We measured tree height of 2493 living individuals in 57 plots and specific root length(SRL)on first-order roots of 368 of these individuals across different species richness levels(1,2,4,8 species)in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China(BEF-China)established in 2009.We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity(RaoQ)and further effects of species interactions by variable components of interspecific and intraspecific functional diversity(community weighted trait similarity and trait dissimilarity,CWS and CWD).Finally,we examined the relationships between biodiversity effects on stand-level tree height and functional diversity(RaoQ,CWS and CWD)in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.Important Findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species.A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL.A positive CE was related to high values of all three components of root functional diversity(RaoQ,CWS and CWD).Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.Wensheng Bu Bernhard Schmid Xiaojuan Liu Ying Li Werner Härdtle Goddert von Oheimb Yu Liang Zhenkai Sun Yuanyuan Huang Helge Bruelheide Keping Ma 2017Journal of Plant Ecology2017,10,1:18
4Impact of tree diversity and environmental conditions on the survival of shrub species in a forest biodiversity experiment in subtropical China显示文摘Aims Although shrubs are an important component of forests,their role has not yet been considered in forest biodiversity experiments.In the biodiversity-ecosystem functioning(BEF)experiment with subtropical tree species in south-east China(BEF-China),we factorially combined tree with shrub species-diversity treatments.Here,we tested the hypotheses that shrub survival differs between the 10 planted shrub species,with lower survival rates of late-than early-successional species and is affected by environmental conditions,such as topography and top soil characteristics,as well as by biotic factors,represented by tree,shrub and herb layer characteristics.Methods We analyzed the survival of 42000 shrub individuals in 105 plots varying in tree and shrub species richness of the BEF-China project four years after planting.Shrub survival was analyzed with generalized linear mixed effects models at the level of individuals and with variance partitioning at the plot level.Random intercept and random slope models of different explanatory variables were compared with respect to the Bayesian Information Criterion(BIC).Important Findings Survival rates differed largely between the 10 shrub species,ranging from 26%to 91%for Ardisia crenata and Distylium buxifolium,respectively.Irrespective of species identity,single abiotic factors explained up to 5%of species survival,with a negative effect of altitude and slope inclination and a positive effect of the topsoil carbon to nitrogen ratio,which pointed to drought as the major cause of shrub mortality.In contrast,neither tree nor shrub richness affected shrub survival at this early stage of the experiment.Among the biotic predictors,only herb layer species richness and cover of the dominant fern species(Dicranopteris pedata)affected shrub survival.Overall,our models that included all variables could explain about 65%in shrub survival,with environmental variables being most influential,followed by shrub species identity,while tree species diversity(species richness and identity)and herb layer characteristics contributed much less.Thus,in this early stage of the experiment the biotic interactions among shrubs and between shrubs and trees have not yet overruled the impact of abiotic environmental factors.Bo Yang Ying Li Bingyang Ding Sabine Both Alexandra Erfmeier Werner Härdtle Keping Ma Bernhard Schmid Thomas Scholten Gunnar Seidler Goddert von Oheimb Xuefei Yang Helge Bruelheide 2017Journal of Plant Ecology2017,10,1:7
5Integrated photonic systems based on transformation optics enabled gradient index devices显示文摘Integrated photonics is expected to play an increasingly important role in optical communications,imaging,computing and sensing with the promise for significant reduction in the cost and weight of these systems.Future advancement of this technology is critically dependent on an ability to develop compact and reliable optical components and facilitate their integration on a common substrate.Here we reveal,with the utility of the emerging transformation optics technique,that functional components composed of planar gradient index materials can be designed and readily integrated into photonic circuits.The unprecedented design flexibility of transformation optics allows for the creation of a number of novel devices,such as a light source collimator,waveguide adapters and a waveguide crossing,which have broad applications in integrated photonic chips and are compatible with current fabrication technology.Using the finite-difference time-domain method,we perform full-wave numerical simulations to demonstrate their superior optical performance and efficient integration with other components in an on-chip photonic system.These components only require spatially-varying dielectric materials with no magnetic properties,facilitating low-loss,broadband operation in an integrated photonic environment.Qi Wu Jeremiah P Turpin Douglas H Werner 2012Light(Science & Applications)2012,1,1:6
6Does the stock market overreact显示文摘Bondt De Werner F M Thaler R H 1985Journal of Finance1985,40,3:2
7Further evidence on investor overreaction and stock market seasonality显示文摘Bondt De Werner F M Thaler R H 1987Journal of Finance1987,42,3:2
8Continuous quality and shelf life monitoring of retail-packed fresh cod loins in comparison with conventional methods显示文摘Nga T.T. Mai María Gudjónsdóttir Hélène L. Lauzon Kolbrún Sveinsdóttir Emilía Martinsdóttir Hubert Audorff Werner Reichstein Dietrich Haarer Sigurdur G. Bogason Sigurjón Arason 2010Food Control2010,,6:2
9Two-dimensional phase unwrapping显示文摘Goldstein R M Zebker H A Werner C L 1988Radio Sci1988,23,4:1
10The effect of metallization on the ohmic contact resistivity to heavily B-doped polycrystalline diamond films显示文摘WERNER M DORSCH O BAERWIND H U 1995IEEE Trans Electron Devices1995,42,7:1
11Fractal antenna engineering: The theory and design of fractal antenna arrays显示文摘WERNER D H HAUPT R L WERNER P L 1999IEEE Antennas Propagat Mag1999,41,5:1
12Characterization and identification of eytoehrome P450 metabolites of arachidonic acid released by human peritoneal maerophages obtained from the pouch of Douglas显示文摘Werner K Schaefer W R Schweer H 2002Prastaglandins Leukot Essent Fatty Acids2002,67,6:1
133 -D FEM-simulation of hot forming processes for the production of a connecting md 显示文摘GRASS H KREMPLASZKY C WERNER E 2006Computational Materials Science2006,36,4:1
14An auto polyploidy-based genetic algorithm for enhanced evolution of linear polyfractal arrays 显示文摘PETKO J S WERNER D H 2007IEEE Trans on Antenas and Propagation2007,55,3:1
15Comparison of the rapid proapoptotic effect of trans-beta-nitrostyrenes with delayed apoptosis induced by the standard agent 5-fluorouracil in colon cancer cells显示文摘Werner M Eger K Jurgen-Steinfelder H 0,,:1
16Reduction of serum endothelin1 levels by pneumatic external counterpulsation显示文摘Garlichs CD Zhang H Werner D 1998Can J Cardiol1998,14,4:1
17Radiation characteristics of thin-wire ternary fractal trees 显示文摘Werner D H Rubio B A Long B R 1996Electronics Letters1996,35,8:1
18Dysregulation of the type 1 IGF receptor as a paradigm in tumor progression显示文摘Werner H 1998Mol Cell Endocrinol1998,141,:1
19The enhanced plasma levels of soluble tumor necrosis factor receptors (sTNF-R1; sTNF-R2) and interleukin-10 (IL-10) in patients suffering from chronic heart failure are reversed inpatients treated with β-adrenoceptor antagonist 显示文摘LOPPNOW H WERDAN K WERNER C 2002Auton Autacoid Pharmacol2002,22,:1
20Alternative back contact materials for thin-film Cu (In, Ga)Sez solar cells显示文摘Orgassa K Sehock H W Werner J H 2003Thin Solid Films2003,,:1
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