TY - JOUR T1 - Nutrients and herbivores impact grassland stability across spatial scales through different pathways JF - 28 Y1 - 2022 A1 - Chen, Qingqing A1 - Wang, Shaopeng A1 - Seabloom, E.W. A1 - MacDougall, A.S. A1 - Borer, E.T. A1 - Bakker, Jonathan D. A1 - Donohue, Ian. A1 - Knops, J.M.H. A1 - Morgan, J.W. A1 - Carroll, Oliver. A1 - Crawley, M. A1 - Bugalho, M.N. A1 - Power, S.A. A1 - Eskelinen, A. A1 - Virtanen, R. AB -

Nutrients and herbivores are well-known drivers of grassland diversity and stability in local communities. However, whether they interact to impact the stability of aboveground biomass and whether these effects depend on spatial scales remain unknown. It is also unclear whether nutrients and herbivores impact stability via different facets of plant diversity including species richness, evenness, and changes in community composition through time and space. We used a replicated experiment adding nutrients and excluding herbivores for 5 years in 34 global grasslands to explore these questions. We found that both nutrient addition and herbivore exclusion alone reduced stability at the larger spatial scale (aggregated local communities; gamma stability), but through different pathways. Nutrient addition reduced gamma stability primarily by increasing changes in local community composition over time, which was mainly driven by species replacement. Herbivore exclusion reduced gamma stability primarily by decreasing asynchronous dynamics among local communities (spatial asynchrony). Their interaction weakly increased gamma stability by increasing spatial asynchrony. Our findings indicate that disentangling the processes operating at different spatial scales may improve conservation and management aiming at maintaining the ability of ecosystems to reliably provide functions and services for humanity.

VL - 8 UR - https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.16086 ER - TY - JOUR T1 - Increasing effects of chronic nutrient enrichment on plant diversity loss and ecosystem productivity over time JF - Ecology Y1 - 2021 A1 - Seabloom, E.W. A1 - Adler, P.B. A1 - Alberti, J. A1 - Biederman, L. A1 - Buckley, Y.M. A1 - Cadotte, M.W. A1 - S.L Collins A1 - Dee, L. A1 - Fay, P.A. A1 - Firn, J. A1 - Hagenah, N. A1 - Harpole, W. S. A1 - Hautier, Y. A1 - Hector, A. A1 - Hobbie, S.E. A1 - Isbell, F. A1 - Knops, J.M.H. A1 - Kimberly J. Komatsu A1 - Laungani, R. A1 - MacDougall, A. A1 - McCulley, R.L. A1 - Moore, J.L. A1 - Morgan, J.W. A1 - Ohlert, T. A1 - Prober, S.M. A1 - Risch, A.C. A1 - Schuetz, M. A1 - Stevens, C.J. A1 - Borer, E.T. AB -

Human activities are enriching many of Earth’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N) and phosphorus (P). In grasslands, this enrichment generally reduces plant diversity and increases productivity. The widely demonstrated positive effect of diversity on productivity suggests a potential negative feedback, whereby nutrient‐induced declines in diversity reduce the initial gains in productivity arising from nutrient enrichment. In addition, plant productivity and diversity can be inhibited by accumulations of dead biomass, which may be altered by nutrient enrichment. Over longer timeframes, nutrient addition may increase soil fertility by increasing soil organic matter and nutrient pools. We examined the effects of 5‐11 years of nutrient addition at 47 grasslands in twelve countries. Nutrient enrichment increased aboveground live biomass and reduced plant diversity at nearly all sites, and these effects became stronger over time. We did not find evidence that nutrient‐induced losses of diversity reduced the positive effects of nutrients on biomass, however nutrient effects on live biomass increased more slowly at sites where litter was also increasing, regardless of plant diversity. This work suggests that short‐term experiments may underestimate the long‐term nutrient enrichment effects on global, grassland ecosystems.

VL - 102 UR - https://onlinelibrary.wiley.com/doi/10.1002/ecy.3218 IS - 2 ER - TY - JOUR T1 - Global change effects on plant communities are magnified by time and the number of global change factors imposed JF - Proceedings of the National Academy of Sciences Y1 - 2019 A1 - Kimberly J. Komatsu A1 - M.L. Avolio A1 - Lemoine, Nathan P. A1 - Isbell, Forest A1 - Grman, Emily A1 - Houseman, Gregory R. A1 - Koerner, Sally E. A1 - Johnson, D.S. A1 - K.R. Wilcox A1 - Juha M. Alatalo A1 - Anderson, J.P. A1 - Aerts, R. A1 - S.G. Baer A1 - Baldwin, Andrew H. A1 - Bates, J. A1 - Beierkuhnlein, C. A1 - Belote, R.T. A1 - John M. Blair A1 - Bloor, J.M.G. A1 - Bohlen, P.J. A1 - Edward W. Bork A1 - Elizabeth H. Boughton A1 - W.D. Bowman A1 - Britton, Andrea J. A1 - Cahill, James F. A1 - Chaneton, Enrique J. A1 - Chiariello, N.R. A1 - Cheng, Jimin. A1 - Scott. L. Collins A1 - Cornelissen, J.H.C. A1 - G. Du A1 - Eskelinen, Anu A1 - Firn, Jennifer A1 - Foster, B. A1 - Gough, L. A1 - Gross, K. A1 - Hallett, L.M. A1 - Han, X. A1 - Harmens, H. A1 - Hovenden, M.J. A1 - Jagerbrand, A. A1 - Jentsch, A. A1 - Kern, Christel A1 - Klanderud, Kari A1 - Alan K. Knapp A1 - Kreyling, Juergen A1 - Li, W. A1 - Luo, Yiqi A1 - McCulley, R.L. A1 - McLaren, Jennie R. A1 - Megonigal, Patrick A1 - J.W. Morgan A1 - Onipchenko, Vladimir A1 - Pennings, S.C. A1 - Prevéy, J.S. A1 - Price, Jodi N. A1 - P.B. Reich A1 - Robinson, Clare H. A1 - Russell, L.F. A1 - Sala, O.E. A1 - Seabloom, E.W. A1 - M.D. Smith A1 - Soudzilovskaia, Nadejda A. A1 - Souza, Lara A1 - K.N. Suding A1 - Suttle, B.K. A1 - Svejcar, T. A1 - Tilman, David A1 - Tognetti, P. A1 - Turkington, R. A1 - White, S. A1 - Xu, Zhuwen A1 - Yahdjian, L. A1 - Yu, Q. A1 - Zhang, Pengfei A1 - Zhang, Yunhai AB -

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (<10 y). In contrast, long-term (≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

VL - 116 UR - https://www.pnas.org/content/early/2019/08/14/1819027116 IS - 36 ER - TY - JOUR T1 - Addition of multiple limiting resources reduces grassland diversity JF - Nature Y1 - 2016 A1 - Harpole, W. S. A1 - L.L. Sullivan A1 - Lind, E.M. A1 - Firn, J. A1 - P. Adler A1 - E.T. Borer A1 - Chase, J. A1 - Fay, P.A. A1 - Hautier, Y. A1 - Hillebrand, H. A1 - MacDougall, A.S. A1 - Seabloom, E.W. A1 - Williams, R. A1 - J.D. Bakker A1 - Cadotte, M.W. A1 - Chaneton, E.J. A1 - Chu, C. A1 - Cleland, E.E. A1 - Antonio, C. A1 - Davies, K.F. A1 - Gruner, D.S. A1 - Hagenah, N. A1 - Kirkman, K. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - McCulley, R.L. A1 - Joslin L. Moore A1 - J.W. Morgan A1 - Prober, S.M. A1 - A. Risch A1 - Schuetz, M. A1 - Stevens, C.J. A1 - Wragg, P.D. AB -

Niche dimensionality provides a general theoretical explanation for biodiversity—more niches, defined by more limiting factors, allow for more ways that species can coexist1. Because plant species compete for the same set of limiting resources, theory predicts that addition of a limiting resource eliminates potential trade-offs, reducing the number of species that can coexist2. Multiple nutrient limitation of plant production is common and therefore fertilization may reduce diversity by reducing the number or dimensionality of belowground limiting factors. At the same time, nutrient addition, by increasing biomass, should ultimately shift competition from belowground nutrients towards a one-dimensional competitive trade-off for light3. Here we show that plant species diversity decreased when a greater number of limiting nutrients were added across 45 grassland sites from a multi-continent experimental network4. The number of added nutrients predicted diversity loss, even after controlling for effects of plant biomass, and even where biomass production was not nutrient-limited. We found that elevated resource supply reduced niche dimensionality and diversity and increased both productivity5 and compositional turnover. Our results point to the importance of understanding dimensionality in ecological systems that are undergoing diversity loss in response to multiple global change factors.

VL - 537 UR - https://www.nature.com/articles/nature19324 JO - Nature ER - TY - JOUR T1 - Climate modifies response of non-native and native species richness to nutrient enrichment JF - Philosophical Transactions of the Royal Society B: Biological Sciences Y1 - 2016 A1 - Flores-Moreno, H. A1 - P.B. Reich A1 - Lind, E.M. A1 - L.L. Sullivan A1 - Seabloom, E.W. A1 - Yahdjian, L. A1 - MacDougall, A.S. A1 - Reichmann, L.G. A1 - J. Alberti A1 - Báez, S. A1 - J.D. Bakker A1 - Cadotte, M.W. A1 - Caldeira, M.C. A1 - Chaneton, E.J. A1 - D'Antonio, C.M. A1 - Fay, P.A. A1 - Firn, J. A1 - Hagenah, N. A1 - Harpole, W. S. A1 - Iribarne, O. A1 - Kirkman, K.P. A1 - Knops, J.M. H. A1 - Kimberly J. La Pierre A1 - Laungani, R. A1 - Leakey, A.D. B. A1 - McCulley, R.L. A1 - Joslin L. Moore A1 - Pascual, J. A1 - E.T. Borer AB -

Ecosystem eutrophication often increases domination by non-natives and causes displacement of native taxa. However, variation in environmental conditions may affect the outcome of interactions between native and non-native taxa in environments where nutrient supply is elevated. We examined the interactive effects of eutrophication, climate variability and climate average conditions on the success of native and non-native plant species using experimental nutrient manipulations replicated at 32 grassland sites on four continents. We hypothesized that effects of nutrient addition would be greatest where climate was stable and benign, owing to reduced niche partitioning. We found that the abundance of non-native species increased with nutrient addition independent of climate; however, nutrient addition increased non-native species richness and decreased native species richness, with these effects dampened in warmer or wetter sites. Eutrophication also altered the time scale in which grassland invasion responded to climate, decreasing the importance of long-term climate and increasing that of annual climate. Thus, climatic conditions mediate the responses of native and non-native flora to nutrient enrichment. Our results suggest that the negative effect of nutrient addition on native abundance is decoupled from its effect on richness, and reduces the time scale of the links between climate and compositional change.

VL - 3719371 UR - https://royalsocietypublishing.org/doi/10.1098/rstb.2015.0273 IS - 1694 ER - TY - JOUR T1 - Integrative modelling reveals mechanisms linking productivity and plant species richness JF - Nature Y1 - 2016 A1 - Grace, J.B. A1 - Anderson, T.M. A1 - Seabloom, E.W. A1 - E.T. Borer A1 - P. Adler A1 - Harpole, W.S. A1 - Hautier, Y. A1 - Hillebrand, H. A1 - Lind, E.M. A1 - Pärtel, M. A1 - J.D. Bakker A1 - Buckley, Y.M. A1 - Crawley, M.J. A1 - Damschen, E.I. A1 - Davies, K.F. A1 - Fay, P.A. A1 - Firn, J. A1 - Gruner, D.S. A1 - Hector, A. A1 - Knops, J.M.H. A1 - MacDougall, A.S. A1 - Melbourne, B.A. A1 - J.W. Morgan A1 - Orrock, J.L. A1 - Prober, S.M. A1 - M.D. Smith AB -

How ecosystem productivity and species richness are interrelated is one of the most debated subjects in the history of ecology1. Decades of intensive study have yet to discern the actual mechanisms behind observed global patterns2, 3. Here, by integrating the predictions from multiple theories into a single model and using data from 1,126 grassland plots spanning five continents, we detect the clear signals of numerous underlying mechanisms linking productivity and richness. We find that an integrative model has substantially higher explanatory power than traditional bivariate analyses. In addition, the specific results unveil several surprising findings that conflict with classical models4, 5, 6, 7. These include the isolation of a strong and consistent enhancement of productivity by richness, an effect in striking contrast with superficial data patterns. Also revealed is a consistent importance of competition across the full range of productivity values, in direct conflict with some (but not all) proposed models. The promotion of local richness by macroecological gradients in climatic favourability, generally seen as a competing hypothesis8, is also found to be important in our analysis. The results demonstrate that an integrative modelling approach leads to a major advance in our ability to discern the underlying processes operating in ecological systems.

VL - 529 UR - https://www.nature.com/articles/nature16524 IS - 7586 ER - TY - JOUR T1 - Consistent responses of soil microbial communities to elevated nutrient inputs in grasslands across the globe JF - Proceedings of the National Academy of Sciences Y1 - 2015 A1 - Leff, J.W. A1 - Jones, S.E. A1 - Prober, S.M. A1 - Barberán, A. A1 - E.T. Borer A1 - Firn, J.L. A1 - Harpole, W.S. A1 - Hobbie, S.E. A1 - Hofmockel, K.S. A1 - Knops, J.M.H. A1 - McCulley, R.L. A1 - Kimberly J. La Pierre A1 - A. Risch A1 - Seabloom, E.W. A1 - Schütz, Martin A1 - Steenbock, C. A1 - Stevens, C.J. A1 - Fierer, N. KW - Fertilization KW - shotgun metagenomics KW - Soil bacteria KW - Soil ecology KW - Soil fungi AB -

Soil microorganisms are critical to ecosystem functioning and the maintenance of soil fertility. However, despite global increases in the inputs of nitrogen (N) and phosphorus (P) to ecosystems due to human activities, we lack a predictive understanding of how microbial communities respond to elevated nutrient inputs across environmental gradients. Here we used high-throughput sequencing of marker genes to elucidate the responses of soil fungal, archaeal, and bacterial communities using an N and P addition experiment replicated at 25 globally distributed grassland sites. We also sequenced metagenomes from a subset of the sites to determine how the functional attributes of bacterial communities change in response to elevated nutrients. Despite strong compositional differences across sites, microbial communities shifted in a consistent manner with N or P additions, and the magnitude of these shifts was related to the magnitude of plant community responses to nutrient inputs. Mycorrhizal fungi and methanogenic archaea decreased in relative abundance with nutrient additions, as did the relative abundances of oligotrophic bacterial taxa. The metagenomic data provided additional evidence for this shift in bacterial life history strategies because nutrient additions decreased the average genome sizes of the bacterial community members and elicited changes in the relative abundances of representative functional genes. Our results suggest that elevated N and P inputs lead to predictable shifts in the taxonomic and functional traits of soil microbial communities, including increases in the relative abundances of faster-growing, copiotrophic bacterial taxa, with these shifts likely to impact belowground ecosystems worldwide.

VL - 112 UR - https://www.pnas.org/content/112/35/10967 IS - 35 ER - TY - JOUR T1 - Grassland productivity limited by multiple nutrients JF - Nature Plants Y1 - 2015 A1 - Fay, P.A. A1 - Prober, S.M. A1 - Harpole, W.S. A1 - Knops, J.M.H. A1 - J.D. Bakker A1 - E.T. Borer A1 - Lind, E.M. A1 - MacDougall, A.S. A1 - Seabloom, E.W. A1 - Wragg, P.D. A1 - P. Adler A1 - D.M. Blumenthal A1 - Buckley, Y.M. A1 - Chu, C. A1 - Cleland, E.E. A1 - Scott. L. Collins A1 - Davies, K.F. A1 - G. Du A1 - Feng, X. A1 - Firn, J. A1 - Gruner, D.S. A1 - Hagenah, N. A1 - Hautier, Y. A1 - Heckman, R.W. A1 - Jin, V.L. A1 - Kirkman, K.P. A1 - Klein, J. A1 - L. Ladwig A1 - Li, Q. A1 - McCulley, R.L. A1 - Melbourne, B.A. A1 - Mitchell, C.E. A1 - Joslin L. Moore A1 - J.W. Morgan A1 - A. Risch A1 - schütz, M. A1 - Stevens, C.J. A1 - Wedin, D.A. A1 - Yang, L.H. AB -

Terrestrial ecosystem productivity is widely accepted to be nutrient limited1. Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP)2,3, the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized4,​5,​6,​7,​8. However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+μ), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+μ co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.

VL - 1 UR - https://www.nature.com/articles/nplants201580 IS - 7 ER - TY - JOUR T1 - Plant diversity predicts beta but not alpha diversity of soil microbes across grasslands worldwide JF - Ecology Letters Y1 - 2015 A1 - Prober, S.M. A1 - Leff, J.W. A1 - Bates, S.T. A1 - E.T. Borer A1 - Firn, J. A1 - Harpole, W.S. A1 - Lind, E.M. A1 - Seabloom, E.W. A1 - P. Adler A1 - J.D. Bakker A1 - E.E Cleland A1 - DeCrappeo, N.M. A1 - DeLorenze, E. A1 - Hagenah, N. A1 - Hautier, Y. A1 - Hofmockel, K.S. A1 - Kirkman, K.P. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - MacDougall, A.S. A1 - McCulley, R.L. A1 - Mitchell, C.E. A1 - A. Risch A1 - Schuetz, M. A1 - Stevens, C.J. A1 - Williams, R.J. A1 - Fierer, N. AB -

Aboveground–belowground interactions exert critical controls on the composition and function of terrestrial ecosystems, yet the fundamental relationships between plant diversity and soil microbial diversity remain elusive. Theory predicts predominantly positive associations but tests within single sites have shown variable relationships, and associations between plant and microbial diversity across broad spatial scales remain largely unexplored. We compared the diversity of plant, bacterial, archaeal and fungal communities in one hundred and forty-five 1 m2 plots across 25 temperate grassland sites from four continents. Across sites, the plant alpha diversity patterns were poorly related to those observed for any soil microbial group. However, plant beta diversity (compositional dissimilarity between sites) was significantly correlated with the beta diversity of bacterial and fungal communities, even after controlling for environmental factors. Thus, across a global range of temperate grasslands, plant diversity can predict patterns in the composition of soil microbial communities, but not patterns in alpha diversity.

VL - 18 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.12381 ER - TY - JOUR T1 - Plant species’ origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands JF - Nature Communications Y1 - 2015 A1 - Seabloom, E.W. A1 - E.T. Borer A1 - Buckley, Y. A1 - Cleland, E.E. A1 - Davies, K.F. A1 - Firn, J. A1 - Harpole, W.S. A1 - Hautier, Y. A1 - Lind, E. A1 - MacDougall, A.S. A1 - Orrock, J.L. A1 - Prober, S.M. A1 - P. Adler A1 - Anderson, T.M. A1 - J.D. Bakker A1 - L.A. Biederman A1 - D.M. Blumenthal A1 - C.S. Brown A1 - Brudvig, L.A. A1 - Cadotte, M. A1 - Chu, C. A1 - Cottingham, K.L. A1 - Crawley, M.J. A1 - Damschen, E.I. A1 - D’Antonio, C.M. A1 - CeCrappeo, N.M. A1 - G. Du A1 - Fay, P.A. A1 - Frater, P. A1 - Gruner, D.S. A1 - Hagenah, N. A1 - Hector, A. A1 - Hillebrand, H. A1 - Hofmockel, K.S. A1 - Humphries, H.C. A1 - Jin, V.L. A1 - Kay, A.D. A1 - Kirkman, K.P. A1 - Klein, J.A. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - L. Ladwig A1 - Lambrinos, J.G. A1 - Li, Q. A1 - Li, W. A1 - Marushia, R. KW - Biological sciences KW - ecology KW - Plant sciences AB -

Exotic species dominate many communities; however the functional significance of species’ biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native diversity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands.

VL - 6 UR - https://www.nature.com/articles/ncomms8710 ER - TY - JOUR T1 - Anthropogenic-based regional-scale factors most consistently explain plot-level exotic diversity in grasslands JF - Global Ecology and Biogeography Y1 - 2014 A1 - MacDougall, A.S. A1 - Bennett, J.R. A1 - Firn, J. A1 - Seabloom, E.W. A1 - E.T. Borer A1 - Lind, E.M. A1 - Orrock, J.L. A1 - Harpole, W.S. A1 - Hautier, Y. A1 - P. Adler A1 - Cleland, E. A1 - Davies, K. A1 - Melbourne, B. A1 - Prober, S.M. A1 - J.D. Bakker A1 - Fay, P.A. A1 - Jin, V.L. A1 - Kendig, A. A1 - Kimberly J. La Pierre A1 - Joslin L. Moore A1 - J.W. Morgan A1 - Stevens, C.J. AB -

Aim Evidence linking the accumulation of exotic species to the suppression of native diversity is equivocal, often relying on data from studies that have used different methods. Plot-level studies often attribute inverse relationships between native and exotic diversity to competition, but regional abiotic filters, including anthropogenic influences, can produce similar patterns. We seek to test these alternatives using identical scale-dependent sampling protocols in multiple grasslands on two continents. Location Thirty-two grassland sites in North America and Australia. Methods We use multiscale observational data, collected identically in grain and extent at each site, to test the association of local and regional factors with the plot-level richness and abundance of native and exotic plants. Sites captured environmental and anthropogenic gradients including land-use intensity, human population density, light and soil resources, climate and elevation. Site selection occurred independently of exotic diversity, meaning that the numbers of exotic species varied randomly thereby reducing potential biases if only highly invaded sites were chosen. Results Regional factors associated directly or indirectly with human activity had the strongest associations with plot-level diversity. These regional drivers had divergent effects: urban-based economic activity was associated with high exotic : native diversity ratios; climate- and landscape-based indicators of lower human population density were associated with low exotic : native ratios. Negative correlations between plot-level native and exotic diversity, a potential signature of competitive interactions, were not prevalent; this result did not change along gradients of productivity or heterogeneity. Main conclusion We show that plot-level diversity of native and exotic plants are more consistently associated with regional-scale factors relating to urbanization and climate suitability than measures indicative of competition. These findings clarify the long-standing difficulty in resolving drivers of exotic diversity using single-factor mechanisms, suggesting that multiple interacting anthropogenic-based processes best explain the accumulation of exotic diversity in modern landscapes.

VL - 23 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12157 IS - 7 ER - TY - JOUR T1 - Eutrophication weakens stabilizing effects of diversity in natural grasslands JF - Nature Y1 - 2014 A1 - Hautier, Y. A1 - Seabloom, E.W. A1 - E.T. Borer A1 - P. Adler A1 - Harpole, W.S. A1 - Hillebrand, H. A1 - Lind, E.M. A1 - MacDougall, A.S. A1 - Stevens, C.J. A1 - J.D. Bakker A1 - Buckley, Y.M. A1 - Chu, C. A1 - Scott. L. Collins A1 - Daleo, P. A1 - Damschen, E.I. A1 - Davies, K.F. A1 - Fay, P.A. A1 - Firn, J. A1 - Gruner, D.S. A1 - Jin, V.L. A1 - Klein, J.A. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - Li, W. A1 - McCulley, R.L. A1 - Melbourne, B.A. A1 - Joslin L. Moore A1 - O’Halloran, L.R. A1 - Prober, S.M. A1 - A. Risch A1 - Sankaran, M. A1 - Schuetz, M. A1 - Hector, A. KW - Biodiversity KW - Community ecology KW - Grassland ecology AB -

Studies of experimental grassland communities1, 2, 3, 4, 5, 6, 7 have demonstrated that plant diversity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others1, 2. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species diversity is threatened by anthropogenic global change8, 9, 10, 11. Here we analyse diversity–stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally8. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from biodiversity experiments to real-world grasslands. However, fertilization weakened the positive effect of diversity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in diverse communities. Our results demonstrate separate and synergistic effects of diversity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.

VL - 508 UR - https://www.nature.com/articles/nature13014 ER - TY - JOUR T1 - Herbivores and nutrients control grassland plant diversity via light limitation JF - Nature Y1 - 2014 A1 - E.T. Borer A1 - Seabloom, E.W. A1 - Gruner, D.S. A1 - Harpole, W.S A1 - Hillebrand, H. A1 - Lind, E.M. A1 - P. Adler A1 - J. Alberti A1 - Anderson, T.M. A1 - J.D. Bakker A1 - L.A. Biederman A1 - D.M. Blumenthal A1 - C.S. Brown A1 - Brudvig, L.A. A1 - Buckley, Y.M. A1 - Cadotte, M. A1 - Chu, C. A1 - Cleland, E.E. A1 - Crawley, M.J. A1 - Daleo, P. A1 - Damschen, E.I. A1 - Davies, K.F. A1 - DeCrappeo, N.M. A1 - G. Du A1 - Firn, J. A1 - Hautier, Y. A1 - Heckman, R.W. A1 - Hector, A. A1 - HilleRisLambers, J. A1 - Iribarne, Oscar A1 - Klein, J.A. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - Leakey, A.D.B. A1 - Li, W. A1 - MacDougall, A.S. A1 - McCulley, R.L. A1 - Melbourne, B.A. A1 - Mitchell, C.E. A1 - Joslin L. Moore A1 - Mortensen, B. A1 - O'Halloran, L.R. A1 - Orrock, J.L. A1 - Pascual, J. A1 - Prober, S.M. A1 - Pyke, D.A. A1 - A. Risch A1 - Schuetz, M. A1 - M.D. Smith A1 - Stevens, C.J. A1 - L.L. Sullivan A1 - Williams, R.J. A1 - Wragg, P.D. A1 - Wright, J.P. A1 - Yang, L.H. VL - 508 UR - https://www.nature.com/articles/nature13144 IS - 7497 ER - TY - JOUR T1 - Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness? JF - Global Change Biology Y1 - 2013 A1 - Seabloom, E.W. A1 - E.T. Borer A1 - Buckley, Y. A1 - Cleland, E.E. A1 - Davies, K. A1 - Firn, J. A1 - Harpole, W.S. A1 - Hautier, Y. A1 - Lind, E. A1 - MacDougall, A. A1 - Orrock, J.L. A1 - Prober, S.M. A1 - P. Adler A1 - J. Alberti A1 - Anderson, M.T. A1 - J.D. Bakker A1 - L.A. Biederman A1 - D.M. Blumenthal A1 - C.S. Brown A1 - Brudvig, L.A. A1 - Caldeira, M. A1 - Chu, C. A1 - Crawley, M.J. A1 - Daleo, P. A1 - Damschen, E.I. A1 - D'Antonio, C.M. A1 - DeCrappeo, N.M. A1 - Dickman, C.R. A1 - G. Du A1 - Fay, P.A. A1 - Frater, P. A1 - Gruner, D.S. A1 - Hagenah, N. A1 - Hector, A. A1 - Helm, A. A1 - Hillebrand, H. A1 - Hofmockel, K.S. A1 - Humphries, H.C. A1 - Iribarne, O. A1 - Jin, V.L. A1 - Kay, A. A1 - Kirkman, K.P. A1 - Klein, J.A. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - L. Ladwig A1 - Lambrinos, J.G. A1 - Leakey, A.D.B. A1 - Li, Q. A1 - Li, W. A1 - McCulley, R. A1 - Melbourne, B. A1 - Mitchell, C.E. A1 - Joslin L. Moore A1 - J.W. Morgan A1 - Mortensen, B. A1 - O'Halloran, L.R. A1 - Pärtel, M. A1 - Pascual, J A1 - Pyke, D.A. A1 - A. Risch A1 - Salguero-Gomez, R. A1 - Sankaran, M. A1 - Schuetz, M. A1 - Simonsen, A. A1 - M.D. Smith A1 - Stevens, C. A1 - Sullivan, L. A1 - Wardle, G.M. A1 - Wolkovich, E.M. A1 - Wragg, P.D. A1 - Wright, J. A1 - Yang, L. AB -

Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community diversity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant diversity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring species' relative abundance will more rapidly advance our understanding of invasions.

VL - 19 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12370 IS - 12 ER - TY - JOUR T1 - Abundance of introduced species at home predicts abundance away in herbaceous communities JF - Ecology Letters Y1 - 2011 A1 - Firn, J. A1 - Joslin L. Moore A1 - MacDougall, A.S. A1 - E.T. Borer A1 - Seabloom, E.W. A1 - HilleRisLambers, J. A1 - Harpole, W.S. A1 - Cleland, E.E. A1 - C.S. Brown A1 - Knops, J.M.H. A1 - Prober, S.M. A1 - Pyke, D.A. A1 - Farrell, K.A. A1 - J.D. Bakker A1 - O’Halloran, L.R. A1 - P. Adler A1 - Scott. L. Collins A1 - D’Antonio, C.M. A1 - Crawley, M.J. A1 - Wolkovich, E.M. A1 - Kimberly J. La Pierre A1 - Melbourne, B.A. A1 - Hautier, Y. A1 - J.W. Morgan A1 - Leakey, A.D.B. A1 - Kay, A.D. A1 - McCulley, R. A1 - Davies, K.F. A1 - Stevens, C.J. A1 - Chu, C. A1 - Holl, K.D. A1 - Klein, J.A. A1 - Fay, P.A. A1 - Hagenah, N. A1 - Kirkman, K.P. A1 - Buckley, Y.M. VL - 14 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1461-0248.2010.01584.x ER - TY - JOUR T1 - Productivity is a poor predictor of plant species richness JF - Science Y1 - 2011 A1 - P. Adler A1 - Seabloom, E.W. A1 - E.T. Borer A1 - Hillebrand, H. A1 - Hautier, Y. A1 - Hector, A. A1 - Harpole, W.S. A1 - O'Halloran, L.R. A1 - Grace, J.B. A1 - Anderson, T.M. A1 - J.D. Bakker A1 - L.A. Biederman A1 - C.S. Brown A1 - Buckley, Y.M. A1 - Calabrese, L.B. A1 - Chu, C.J. A1 - Cleland, E.E. A1 - Scott. L. Collins A1 - Cottingham, K.L. A1 - Crawley, M.J. A1 - Damschen, E.I. A1 - Davies, K.F. A1 - DeCrappeo, N.M. A1 - Fay, P.A. A1 - Firn, J. A1 - Frater, P. A1 - Gasarch, E.I. A1 - Gruner, D.S. A1 - Hagenah, N. A1 - HilleRisLambers, J. A1 - Humphries, H.C. A1 - Jin, V.L. A1 - Kay, A. A1 - Kirkman, K.P. A1 - Klein, J.A. A1 - Knops, J.M.H. A1 - Kimberly J. La Pierre A1 - Lambrinos, J.G. A1 - Li, W. A1 - MacDougall, A.S. A1 - McCulley, R.L. A1 - Melbourne, B.A. A1 - Mitchell, C.E. A1 - Joslin L. Moore AB -

For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters−2) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.

VL - 333 UR - http://science.sciencemag.org/content/333/6050/1750 ER -