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Eric Allan,
Wolfgang W Weisser,
Markus Fischer,
Ernst-Detlef Schulze,
Alexandra Weigelt, Christiane Roscher,
Jussi Baade,
Romain L Barnard,
Holger Beßler,
Nina Buchmann, [......],
Michael Scherer-Lorenzen,
Stefan Scheu,
Sibylle Steinbeiss,
Guido Schwichtenberg,
Vicky Temperton,
Teja Tscharntke,
Winfried Voigt,
Wolfgang Wilcke,
Christian Wirth,
Bernhard Schmid
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ABSTRACT: In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.
Oecologia 02/2013; · 3.41 Impact Factor
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Alexandru Milcu,
Eric Allan, Christiane Roscher,
Tania Jenkins,
Sebastian Tobias Meyer,
Dan F B Flynn,
Holger Bessler,
François Buscot,
Christof Engels,
Marlén Gubsch, [......],
Annett Lipowsky,
Jessy Loranger,
Carsten Renker,
Christoph Scherber,
Bernhard Schmid,
Elisa Thébault,
Tesfaye Wubet,
Wolfgang W Weisser,
Stefan Scheu,
Nico Eisenhauer
Ecology. 01/2013;
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ABSTRACT: In the course of the biodiversity-ecosystem functioning debate, the issue of multifunctionality of species communities has recently become a major focus. Elemental stoichiometry is related to a variety of processes reflecting multiple plant responses to the biotic and abiotic environment. It can thus be expected that the diversity of a plant assemblage alters community level plant tissue chemistry. We explored elemental stoichiometry in aboveground plant tissue (ratios of carbon, nitrogen, phosphorus, and potassium) and its relationship to plant diversity in a 5-year study in a large grassland biodiversity experiment (Jena Experiment). Species richness and functional group richness affected community stoichiometry, especially by increasing C:P and N:P ratios. The primacy of either species or functional group richness effects depended on the sequence of testing these terms, indicating that both aspects of richness were congruent and complementary to expected strong effects of legume presence and grass presence on plant chemical composition. Legumes and grasses had antagonistic effects on C:N (-27.7% in the presence of legumes, +32.7% in the presence of grasses). In addition to diversity effects on mean ratios, higher species richness consistently decreased the variance of chemical composition for all elemental ratios. The diversity effects on plant stoichiometry has several non-exclusive explanations: The reduction in variance can reflect a statistical averaging effect of species with different chemical composition or a optimization of nutrient uptake at high diversity, leading to converging ratios at high diversity. The shifts in mean ratios potentially reflect higher allocation to stem tissue as plants grew taller at higher richness. By showing a first link between plant diversity and stoichiometry in a multiyear experiment, our results indicate that losing plant species from grassland ecosystems will lead to less reliable chemical composition of forage for herbivorous consumers and belowground litter input.
PLoS ONE 01/2013; 8(3):e58179. · 4.09 Impact Factor
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John Connolly,
Thomas Bell,
Thomas Bolger,
Caroline Brophy,
Timothee Carnus,
John A. Finn,
Laura Kirwan,
Forest Isbell,
Jonathan Levine,
Andreas Lüscher,
Valentin Picasso, Christiane Roscher,
Maria Teresa Sebastia,
Matthias Suter,
Alexandra Weigelt
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ABSTRACT: * The development of models of the relationship between biodiversity and ecosystem function (BEF) has advanced rapidly over the last 20 years, incorporating insights gained through extensive experimental work. We propose Generalised Diversity-Interactions models that include many of the features of existing models and have several novel features. Generalised Diversity-Interactions models characterise the contribution of two species to ecosystem function as being proportional to the product of their relative abundances raised to the power of a coefficient θ. * A value of θ < 1 corresponds to a stronger than expected contribution of species' pairs to ecosystem functioning, particularly at low relative abundance of species. * Varying the value of θ has profound consequences for community-level properties of BEF relationships, including: (i) saturation properties of the BEF relationship; (ii) the stability of ecosystem function across communities; (iii) the likelihood of transgressive overyielding. * For low values of θ, loss of species can have a much greater impact on ecosystem functioning than loss of community evenness. * Generalised Diversity-Interactions models serve to unify the modelling of BEF relationships as they include several other current models as special cases. * Generalised Diversity-Interactions models were applied to seven data sets and three functions: total biomass (five grassland experiments), community respiration (one bacterial experiment) and nitrate leaching (one earthworm experiment). They described all the nonrandom structure in the data in six experiments, and most of it in the seventh experiment and so fit as well or better than competing BEF models for these data. They were significantly better than Diversity-Interactions models in five experiments. * Synthesis. We show that Generalized Diversity-Interactions models quantitatively integrate several methods that separately address effects of species richness, evenness and composition on ecosystem function. They describe empirical data at least as well as alternative models and improve the ability to quantitatively test among several theoretical and practical hypotheses about the effects of biodiversity levels on ecosystem function. They improve our understanding of important aspects of the relationship between biodiversity (evenness and richness) and ecosystem function (BEF), which include saturation, effects of species loss, the stability of ecosystem function and the incidence of transgressive overyielding.
Journal of Ecology 01/2013; 101:344-355. · 4.69 Impact Factor
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ABSTRACT: Invertebrate herbivores can impact plant performance and plant communities. Conversely, plants can affect the ability of herbivores to find, choose, and consume them through their functional traits. While single plant traits have been related to rates of herbivory, most often involving single herbivore-plant pairs, much less is known about which suite of plant traits is important for determining herbivory for a pool of plant species interacting with a natural herbivore community. In this study we measured aboveground herbivore damage on 51 herbaceous species growing in monocultures of a grassland biodiversity experiment and collected 42 different plant traits representing four trait groups: physiological, morphological, phenological, and herbivore related. Using the method of random forests and multiple regression, we identified seven traits that are important predictors of herbivore damage (leaf nitrogen and lignin concentration, number of coleopteran and hemipteran herbivores potentially feeding on the plants, leaf life span, stem growth form, and root architecture); leaf nitrogen and lignin concentration were the two most important predictors. The final model accounted for 63% of the variation in herbivore damage. Traits from all four trait groups were selected, showing that a variety of plant characteristics can be statistically important when assessing folivory, including root traits. Our results emphasize that it is necessary to use a multivariate approach for identifying traits affecting complex ecological processes such as herbivory.
Ecology 12/2012; 93(12):2674-82. · 4.85 Impact Factor
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Ecology 09/2012; 94(2):465-477. · 4.85 Impact Factor
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ABSTRACT: Highly variable effects of legumes have been observed in biodiversity experiments, but little is known about plant diversity
effects on N2 fixation of legume species. We used the 15N natural abundance method in a non-fertilized regularly mown 6-year biodiversity experiment (Jena Experiment) to quantify
N2 fixation of 12 legume species. The proportion of legume N derived from the atmosphere (%Ndfa) differed significantly among legume species. %Ndfa values were lower in 2004 after setting-up the experiment (73 ± 20) than in the later years (2006: 80 ± 16; 2008: 78 ± 12).
Increasing species richness had positive effects on %Ndfa in 2004 and 2006, but not in 2008. High biomass production of legumes in 2004 and 2006 declined to lower levels in 2008.
In 2006, legume positioning within the canopy best explained variation in %Ndfa values indicating a lower reliance of tall legumes on N2 fixation. In 2008, larger %Ndfa values of legumes were related to lower leaf P concentrations suggesting that the availability of phosphorus limited growth
of legumes. In summary, diversity effects on N2 fixation depend on legume species identity, their ability to compete for soil nutrients and light and may vary temporally
in response to changing resource availability.
KeywordsBiodiversity–Jena Experiment–Legumes–
15N natural abundance–N2 fixation–Phosphorus
Plant and Soil 05/2012; 341(1):333-348. · 2.73 Impact Factor
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ABSTRACT: Tree-ring width, wood density, anatomical structure and 13C/12C ratios expressed as δ13C-values of whole wood of Picea abies were investigated for trees growing in closed canopy forest stands. Samples were collected from the alpine Renon site in
North Italy, the lowland Hainich site in Central Germany and the boreal Flakaliden site in North Sweden. In addition, Pinus cembra was studied at the alpine site and Pinus sylvestris at the boreal site. The density profiles of tree rings were measured using the DENDRO-2003 densitometer, δ13C was measured using high-resolution laser-ablation-combustion-gas chromatography-infra-red mass spectrometry and anatomical
characteristics of tree rings (tracheid diameter, cell-wall thickness, cell-wall area and cell-lumen area) were measured using
an image analyzer. Based on long-term statistics, climatic variables, such as temperature, precipitation, solar radiation
and vapor pressure deficit, explained <20% of the variation in tree-ring width and wood density over consecutive years, while
29–58% of the variation in tree-ring width were explained by autocorrelation between tree rings. An intensive study of tree
rings between 1999 and 2003 revealed that tree ring width and δ13C-values of whole wood were significantly correlated with length of the growing season, net radiation and vapor pressure deficit.
The δ13C-values were not correlated with precipitation or temperature. A highly significant correlation was also found between δ13C of the early wood of one year and the late wood of the previous year, indicating a carry-over effect of the growing conditions
of the previous season on current wood production. This latter effect may explain the high autocorrelation of long-term tree-ring
statistics. The pattern, however, was complex, showing stepwise decreases as well as stepwise increases in the δ13C between late wood and early wood. The results are interpreted in the context of the biochemistry of wood formation and its
linkage to storage products. It is clear that the relations between δ13C and tree-ring width and climate are multi-factorial in seasonal climates.
KeywordsDendrochonology-Carbohydrate storage-
Picea abies
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Pinus cembra
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Pinus sylvestris
-Tracheid lumen area-Wood density
Oecologia 04/2012; 161(4):729-745. · 3.41 Impact Factor
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ABSTRACT: Differential selection between clones of apomictic species may result in ecological differentiation without mutation and recombination, thus offering a simple system to study adaptation and life-history evolution in plants.
We caused density-independent mortality by weeding to colonizer populations of the largely apomictic Taraxacum officinale (Asteraceae) over a 5-year period in a grassland biodiversity experiment (Jena Experiment). We compared the offspring of colonizer populations with resident populations deliberately sown into similar communities. Plants raised from cuttings and seeds of colonizer and resident populations were grown under uniform conditions. Offspring from colonizer populations had higher reproductive output, which was in general agreement with predictions of r-selection theory. Offspring from resident populations had higher root and leaf biomass, fewer flower heads and higher individual seed mass as predicted under K-selection. Plants grown from cuttings and seeds differed to some degree in the strength, but not in the direction, of their response to the r- vs. K-selection regime. More diverse communities appeared to exert stronger K-selection on resident populations in plants grown from cuttings, while we did not find significant effects of increasing species richness on plants grown from seeds.
Differentiation into r- and K-strategists suggests that clones with characteristics of r-strategists were selected in regularly weeded plots through rapid colonization, while increasing plant diversity favoured the selection of clones with characteristics of K-strategists in resident populations. Our results show that different selection pressures may result in a rapid genetic differentiation within a largely apomictic species. Even under the assumption that colonizer and resident populations, respectively, happened to be r- vs. K-selected already at the start of the experiment, our results still indicate that the association of these strategies with the corresponding selection regimes was maintained during the 5-year experimental period.
PLoS ONE 01/2012; 7(1):e28121. · 4.09 Impact Factor
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ABSTRACT: The different hypotheses proposed to explain positive species richness-productivity relationships, i.e. selection effect and complementarity effect, imply that plant functional characteristics are at the core of a mechanistic understanding of biodiversity effects.
We used two community-wide measures of plant functional composition, (1) community-weighted means of trait values (CWM) and (2) functional trait diversity based on Rao's quadratic diversity (FD(Q)) to predict biomass production and measures of biodiversity effects in experimental grasslands (Jena Experiment) with different species richness (2, 4, 8, 16 and 60) and different functional group number and composition (1 to 4; legumes, grasses, small herbs, tall herbs) four years after establishment. Functional trait composition had a larger predictive power for community biomass and measures of biodiversitity effects (40-82% of explained variation) than species richness per se (<1-13% of explained variation). CWM explained a larger amount of variation in community biomass (80%) and net biodiversity effects (70%) than FD(Q) (36 and 38% of explained variation respectively). FD(Q) explained similar proportions of variation in complementarity effects (24%, positive relationship) and selection effects (28%, negative relationship) as CWM (27% of explained variation for both complementarity and selection effects), but for all response variables the combination of CWM and FD(Q) led to significant model improvement compared to a separate consideration of different components of functional trait composition. Effects of FD(Q) were mainly attributable to diversity in nutrient acquisition and life-history strategies. The large spectrum of traits contributing to positive effects of CWM on biomass production and net biodiversity effects indicated that effects of dominant species were associated with different trait combinations.
Our results suggest that the identification of relevant traits and the relative impacts of functional identity of dominant species and functional diversity are essential for a mechanistic understanding of the role of plant diversity for ecosystem processes such as aboveground biomass production.
PLoS ONE 01/2012; 7(5):e36760. · 4.09 Impact Factor
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ABSTRACT: Aims This study aimed to measure the effect of plant diversity on N uptake in grasslands and to assess the mechanisms contributing to diversity effects. Methods Annual N uptake into above-and below-ground organs and soil nitrate pools were measured in the Jena experiment on a floodplain soil with mixtures of 2–16 species and 1–4 functional groups, and monocultures. In mixtures, the deviation of mea-sured data from data expected from monoculture per-formance was calculated to assess the contribution of complementarity/facilitation and selection. Results N uptake varied from <1 to 45 gN m −2 yr −1 , and was higher in grasslands with than without Plant Soil
Plant and Soil 01/2012; · 2.73 Impact Factor
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ABSTRACT: More diverse communities have been shown to have higher and more temporally stable ecosystem functioning than less diverse ones, suggesting they should also have a consistently higher level of functioning over time. Diverse communities could maintain consistently high function because the species driving function change over time (functional turnover) or because they are more likely to contain key species with temporally stable functioning. Across 7 y in a large biodiversity experiment, we show that more diverse plant communities had consistently higher productivity, that is, a higher level of functioning over time. We identify the mechanism for this as turnover in the species driving biomass production; this was substantial, and species that were rare in some years became dominant and drove function in other years. Such high turnover allowed functionally more diverse communities to maintain high biomass over time and was associated with higher levels of complementarity effects in these communities. In contrast, turnover in communities composed of functionally similar species did not promote high biomass production over time. Thus, turnover in species promotes consistently high ecosystem function when it sustains functionally complementary interactions between species. Our results strongly reinforce the argument for conservation of high biodiversity.
Proceedings of the National Academy of Sciences 09/2011; 108(41):17034-9. · 9.68 Impact Factor
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ABSTRACT: Summary1. While positive effects of biodiversity on temporal stability of communities have been demonstrated in theoretical and empirical studies, diversity–stability relationships at the population level remain poorly understood.2. We investigated temporal variability of plant populations in experimental grassland plots of varying species richness (1, 2, 4, 8, 16–60 species), functional group richness and composition (presence/absence of legumes × grasses × small herbs × tall herbs) in a long-term biodiversity experiment from 2003 to 2009 (‘Jena Experiment’).3. Average population stability, defined as the reciprocal of the coefficient of variation of above-ground biomass production over time, differed largely between species but was generally higher in grasses and small herbs than in legumes and tall herbs. Furthermore, population stability was positively related to a species’ proportional contribution to community biomass. Thus, an increasing number of subordinate species explained lower average population stabilities at higher diversity levels.4. A negative covariance (CV) across all species-richness levels suggested negatively correlated species dynamics. Species belonging to different functional groups fluctuated asynchronously, while species dynamics within functional groups were more synchronous. Community-wide species synchrony decreased with increasing species richness, and temporal stability at the community level increased.5. Synthesis: Our results suggest that diversity–stability relationships are driven by fluctuations in the population biomass of individual species which are less synchronized in more diverse than in less diverse mixtures and monocultures. Dominant plant species tend to be more stabilized than subdominant species, independently of community species richness. However, asynchrony of population dynamics outweighs decreasing population stability with increasing species richness, resulting in higher temporal stability at the plant community level.
Journal of Ecology 07/2011; 99(6):1460 - 1469. · 4.69 Impact Factor
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ABSTRACT: Biodiversity is an important determinant of primary productivity in experimental ecosystems. We combine two streams of research on understanding the effects of biodiversity on ecosystem function: quantifying phylogenetic diversity as a predictor of biodiversity effects in species-rich systems and the contribution of pairwise interspecific interactions to ecosystem function. We developed a statistical model that partitions the effect of biodiversity into effects due to community phylogenetic diversity and other community properties (e.g., average pairwise interaction, between- and within-functional-group effects, and so forth). The model provides phylogenetically based species-level explanations of differences in ecosystem response for communities with differing species composition. In two well-known grassland experiments, the model approach provides a parsimonious description of the effects of diversity as being due to the joint effect of the average pairwise statistical interaction and to community phylogenetic diversity. Effects associated with functional groupings of species in communities are largely explained by community phylogenetic diversity. The model approach quantifies a direct link between a measure of the evolutionary diversity of species and their interactive contribution to ecosystem function. It proves a useful tool in developing a mechanistic understanding of variation in ecosystem function.
Ecology 07/2011; 92(7):1385-92. · 4.85 Impact Factor
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ABSTRACT: Plant diversity was shown to influence the N cycle, but plant diversity effects on other nutrients remain unclear. We tested whether plant species richness or the presence/absence of particular functional plant groups influences P partitioning among differently extractable pools in soil, P concentrations in soil solution, and exploitation of P resources (i.e. the proportion of total bioavailable P in plants and soil that was stored in aboveground biomass) by the plant community in a 5-year biodiversity experiment in grassland. The experimental grassland site established in 2002 had 82 plots with different combinations of numbers of species (1, 2, 4, 8, 16, 60) and functional groups (grasses, small non-leguminous herbs, tall non-leguminous herbs, legumes). In 2007, we determined P partitioning (Hedley) in soil of all experimental plots. We sam-pled plant community biomass and continuously extracted soil solution with suction plates from March 2003 to February 2007 and determined PO 4 -P concentrations in all samples. The presence of legumes increased aboveground P storage in plants and decreased labile P i concentrations in soil because of their higher demands for P associated with N 2 fixation. During cold periods, readily plant-available PO 4 -P concentrations in soil solution increased in legume-containing mixtures likely caused by leaching from P-rich residues. We found a consistently positive effect of plant species richness on P exploita-tion by the plant community which was independent of the presence of particular plant functional groups. With proceeding time after establishment, plant species richness increasingly contributed to the explanation of the variance in P exploitation. Therefore, plant strategies to efficiently acquire P seem to become increas-ingly important in these grasslands. We conclude that diverse plant communities are better prepared than less diverse mixtures to respond to P limitation induced by continuously high atmospheric N deposition.
Geoderma 04/2011; 167-168. · 2.32 Impact Factor
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ABSTRACT: The biological mechanisms of niche complementarity allowing for a stable coexistence of a large number of species in a plant community are still poorly understood. This study investigated how small-statured forbs use environmental niches in light and CO(2) to explain their persistence in diverse temperate grasslands.
Light and CO(2) profiles and the corresponding leaf characteristics of seven small-statured forbs were measured in monocultures and a multi-species mixture within a biodiversity experiment (Jena Experiment) to assess their adjustment to growth conditions in the canopy.
Environmental conditions near the ground varied throughout the season with a substantial CO(2) enrichment (>70 µmol mol(-1) at 2 cm, >20 µmol mol(-1) at 10 cm above soil surface) and a decrease in light transmittance (to <5 % deep in the canopy) with large standing biomass (>500 g d. wt m(-2)) in the multi-species assemblage. Leaf morphology, biochemistry and physiology of small-statured forbs adjusted to low light in the mixture compared with the monocultures. However, the net carbon assimilation balance during the period of low light only compensated the costs of maintenance respiration, while CO(2) enrichment near the ground did not allow for additional carbon gain. Close correlations of leaf mass per area with changes in light availability suggested that small-statured forbs are capable of adjusting to exploit seasonal niches with better light supply for growth and to maintain the carbon metabolism for survival if light transmittance is substantially reduced in multi-species assemblages.
This study shows that adjustment to a highly dynamic light environment is most important for spatial and seasonal niche separation of small-statured forb species in regularly mown, species-rich grasslands. The utilization of short-period CO(2) enrichment developing in dense vegetation close to the ground hardly improves their carbon balance and contributes little to species segregation along environmental niche axes.
Annals of Botany 03/2011; 107(6):965-79. · 4.03 Impact Factor
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ABSTRACT: Plant and soil nitrogen isotope ratios (δ¹⁵N) were studied in experimental grassland plots of varying species richness. We hypothesized that partitioning of different sources of soil nitrogen among four plant functional groups (legumes, grasses, small herbs, tall herbs) should increase with diversity. Four years after sowing, all soils were depleted in ¹⁵N in the top 5 cm whereas in non-legume plots soils were enriched in ¹⁵N at 5-25 cm depth. Decreasing foliar δ¹⁵N and Δδ¹⁵N (= foliar δ¹⁵N-soil δ¹⁵N) values in legumes indicated increasing symbiotic N₂ fixation with increasing diversity. In grasses, foliar Δδ¹⁵N also decreased with increasing diversity suggesting enhanced uptake of N depleted in ¹⁵N. Foliar Δδ¹⁵N values of small and tall herbs were unaffected by diversity. Foliar Δδ¹⁵N values of grasses were also reduced in plots containing legumes, indicating direct use of legume-derived N depleted in ¹⁵N. Increased foliar N concentrations of tall and small herbs in plots containing legumes without reduced foliar δ¹⁵N indicated that these species obtained additional mineral soil N that was not consumed by legumes. These functional group and species specific shifts in the uptake of different N sources with increasing diversity indicate complementary resource use in diverse communities.
Plant Cell and Environment 02/2011; 34(6):895-908. · 5.22 Impact Factor
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ABSTRACT: Plants can respond to environmental impacts by variation in functional traits, thereby increasing their performance relative to neighbors. We hypothesized that trait adjustment should also occur in response to influences of the biotic environment, in particular different plant diversity of the community. We used 12 legume species as a model and assessed their variation in morphological, physiological, life-history and performance traits in experimental grasslands of different plant species (1, 2, 4, 8, 16 and 60) and functional group (1-4) numbers. Mean trait values and their variation in response to plant diversity varied among legume species and from trait to trait. The tall-growing Onobrychis viciifolia showed little trait variation in response to increasing plant diversity, whereas the species with shorter statures responded in apparently adaptive ways. The formation of longer shoots with elongated internodes, increased biomass allocation to supporting tissue at the cost of leaf mass, reduced branching, higher specific leaf areas and lower foliar δ(13)C values indicated increasing efforts for light acquisition in more diverse communities. Although leaf nitrogen concentrations and shoot biomass:nitrogen ratios were not affected by increasing plant diversity, foliar δ(15)N values of most legumes decreased and the application of the (15)N natural abundance method suggested that they became more reliant on symbiotic N(2) fixation. Some species formed fewer inflorescences and delayed flowering with increasing community diversity. The observed variation in functional traits generally indicated strategies of legumes to optimize light and nutrient capturing, but they were largely species-dependent and only partly attributable to increasing canopy height and community biomass with increasing plant diversity. Thus, the analysis of individual plant species and their adjustment to growth conditions in communities of increasing plant diversity is essential to get a deeper insight into the mechanisms behind biodiversity-ecosystem functioning relationships.
Oecologia 02/2011; 165(2):437-52. · 3.41 Impact Factor
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Yvonne Oelmann,
Nina Buchmann,
Gerd Gleixner,
Maike Habekost, Christiane Roscher,
Stephan Rosenkranz,
Ernst‐detlef Schulze,
Sibylle Steinbeiss,
Vicky M Temperton,
Alexandra Weigelt,
Wolfgang W Weisser,
Wolfgang Wilcke
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ABSTRACT: 1] Biodiversity is expected to improve ecosystem services, e.g., productivity or seepage water quality. The current view of plant diversity effects on element cycling is based on short‐term grassland studies that discount possibly slow belowground feedbacks to aboveground diversity. Furthermore, these grasslands were established on formerly arable land associated with changes in soil properties, e.g., accumulation of organic matter. We hypothesize that the plant diversity‐N cycle relationship changes with time since establishment. We assessed the relationship between plant diversity and (1) aboveground and soil N storage and (2) NO 3 ‐N and NH 4 ‐N availability in soil between 2003 and 2007 in the Jena Experiment, a grassland experiment established in 2002 in which the number of plant species varied from 1 to 60. The positive effect of plant diversity on aboveground N storage (mainly driven by biomass production) tended to increase through time. The initially negative correlation between plant diversity and soil NO 3 ‐N availability disappeared after 2003. In 2006 and 2007, a positive correlation between plant diversity and soil NH 4 ‐N availability appeared which coincided with a positive correlation between plant diversity and N mineralized from total N accumulated in soil. We conclude that the plant diversity‐N cycle relationship in newly established grasslands changes with time because of accumulation of organic matter in soil associated with the establishment. While a positive relationship between plant diversity and soil N storage improves soil fertility and reduces fertilizing needs, increasingly closed N cycling with increasing plant diversity as illustrated by decreased NO 3 ‐N concentrations in diverse mixtures reduces the negative impact of agricultural N leaching on groundwater resources.
Global Biogeochemical Cycles 01/2011; 25. · 4.78 Impact Factor
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Nico Eisenhauer,
Alexandru Milcu,
Alexander C W Sabais,
Holger Bessler,
Johanna Brenner,
Christof Engels,
Bernhard Klarner,
Mark Maraun,
Stephan Partsch, Christiane Roscher,
Felix Schonert,
Vicky M Temperton,
Karolin Thomisch,
Alexandra Weigelt,
Wolfgang W Weisser,
Stefan Scheu
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ABSTRACT: One of the most significant consequences of contemporary global change is the rapid decline of biodiversity in many ecosystems. Knowledge of the consequences of biodiversity loss in terrestrial ecosystems is largely restricted to single ecosystem functions. Impacts of key plant functional groups on soil biota are considered to be more important than those of plant diversity; however, current knowledge mainly relies on short-term experiments.
We studied changes in the impacts of plant diversity and presence of key functional groups on soil biota by investigating the performance of soil microorganisms and soil fauna two, four and six years after the establishment of model grasslands. The results indicate that temporal changes of plant community effects depend on the trophic affiliation of soil animals: plant diversity effects on decomposers only occurred after six years, changed little in herbivores, but occurred in predators after two years. The results suggest that plant diversity, in terms of species and functional group richness, is the most important plant community property affecting soil biota, exceeding the relevance of plant above- and belowground productivity and the presence of key plant functional groups, i.e. grasses and legumes, with the relevance of the latter decreasing in time.
Plant diversity effects on biota are not only due to the presence of key plant functional groups or plant productivity highlighting the importance of diverse and high-quality plant derived resources, and supporting the validity of the singular hypothesis for soil biota. Our results demonstrate that in the long term plant diversity essentially drives the performance of soil biota questioning the paradigm that belowground communities are not affected by plant diversity and reinforcing the importance of biodiversity for ecosystem functioning.
PLoS ONE 01/2011; 6(1):e16055. · 4.09 Impact Factor
