%0 Journal Article %J Ecology %D 2021 %T Increasing effects of chronic nutrient enrichment on plant diversity loss and ecosystem productivity over time %A Seabloom, E.W. %A Adler, P.B. %A Alberti, J. %A Biederman, L. %A Buckley, Y.M. %A Cadotte, M.W. %A S.L Collins %A Dee, L. %A Fay, P.A. %A Firn, J. %A Hagenah, N. %A Harpole, W. S. %A Hautier, Y. %A Hector, A. %A Hobbie, S.E. %A Isbell, F. %A Knops, J.M.H. %A Kimberly J. Komatsu %A Laungani, R. %A MacDougall, A. %A McCulley, R.L. %A Moore, J.L. %A Morgan, J.W. %A Ohlert, T. %A Prober, S.M. %A Risch, A.C. %A Schuetz, M. %A Stevens, C.J. %A Borer, E.T. %X

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.

%B Ecology %V 102 %P e03218 %G eng %U https://onlinelibrary.wiley.com/doi/10.1002/ecy.3218 %N 2 %M KNZ002041 %R 10.1002/ecy.3218 %0 Journal Article %J Nature %D 2016 %T Addition of multiple limiting resources reduces grassland diversity %A Harpole, W. S. %A L.L. Sullivan %A Lind, E.M. %A Firn, J. %A P. Adler %A E.T. Borer %A Chase, J. %A Fay, P.A. %A Hautier, Y. %A Hillebrand, H. %A MacDougall, A.S. %A Seabloom, E.W. %A Williams, R. %A J.D. Bakker %A Cadotte, M.W. %A Chaneton, E.J. %A Chu, C. %A Cleland, E.E. %A Antonio, C. %A Davies, K.F. %A Gruner, D.S. %A Hagenah, N. %A Kirkman, K. %A Knops, J.M.H. %A Kimberly J. La Pierre %A McCulley, R.L. %A Joslin L. Moore %A J.W. Morgan %A Prober, S.M. %A A. Risch %A Schuetz, M. %A Stevens, C.J. %A Wragg, P.D. %X

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.

%B Nature %V 537 %P 93-96 %G eng %U https://www.nature.com/articles/nature19324 %M KNZ001755 %R 10.1038/nature19324 %0 Journal Article %J Nature %D 2016 %T Integrative modelling reveals mechanisms linking productivity and plant species richness %A Grace, J.B. %A Anderson, T.M. %A Seabloom, E.W. %A E.T. Borer %A P. Adler %A Harpole, W.S. %A Hautier, Y. %A Hillebrand, H. %A Lind, E.M. %A Pärtel, M. %A J.D. Bakker %A Buckley, Y.M. %A Crawley, M.J. %A Damschen, E.I. %A Davies, K.F. %A Fay, P.A. %A Firn, J. %A Gruner, D.S. %A Hector, A. %A Knops, J.M.H. %A MacDougall, A.S. %A Melbourne, B.A. %A J.W. Morgan %A Orrock, J.L. %A Prober, S.M. %A M.D. Smith %X

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.

%B Nature %V 529 %P 390 - 393 %G eng %U https://www.nature.com/articles/nature16524 %N 7586 %M KNZ001787 %R 10.1038/nature16524 %0 Journal Article %J Ecology %D 2015 %T Anthropogenic nitrogen deposition predicts local grassland primary production worldwide %A Stevens, C.J. %A Lind, E.M. %A Hautier, Y. %A Harpole, W.S. %A E.T. Borer %A Hobbie, S. %A Seabloom, E.Q. %A L. Ladwig %A J.D. Bakker %A Chu, C. %A Scott. L. Collins %A Davies, K.F. %A Firn, J. %A Hillebrand, H. %A Kimberly J. La Pierre %A MacDougall, A.S. %A Melbourne, B.A. %A McCulley, R.L. %A J.W. Morgan %A Orrock, J.L. %A Prober, S.M. %A A. Risch %A Schultz, M. %A Wragg, P.D. %X

Humans dominate many important Earth system processes including the nitrogen (N) cycle. Atmospheric N deposition affects fundamental processes such as carbon cycling, climate regulation, and biodiversity, and could result in changes to fundamental Earth system processes such as primary production. Both modelling and experimentation have suggested a role for anthropogenically altered N deposition in increasing productivity, nevertheless, current understanding of the relative strength of N deposition with respect to other controls on production such as edaphic conditions and climate is limited. Here we use an international multiscale data set to show that atmospheric N deposition is positively correlated to aboveground net primary production (ANPP) observed at the 1-m2 level across a wide range of herbaceous ecosystems. N deposition was a better predictor than climatic drivers and local soil conditions, explaining 16% of observed variation in ANPP globally with an increase of 1 kg N·ha−1·yr−1 increasing ANPP by 3%. Soil pH explained 8% of observed variation in ANPP while climatic drivers showed no significant relationship. Our results illustrate that the incorporation of global N deposition patterns in Earth system models are likely to substantially improve estimates of primary production in herbaceous systems. In herbaceous systems across the world, humans appear to be partially driving local ANPP through impacts on the N cycle.

%B Ecology %V 96 %P 1459 -1465 %G eng %U https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/14-1902.1 %M KNZ001698 %R http://dx.doi.org/10.1890/14-1902.1 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2015 %T Consistent responses of soil microbial communities to elevated nutrient inputs in grasslands across the globe %A Leff, J.W. %A Jones, S.E. %A Prober, S.M. %A Barberán, A. %A E.T. Borer %A Firn, J.L. %A Harpole, W.S. %A Hobbie, S.E. %A Hofmockel, K.S. %A Knops, J.M.H. %A McCulley, R.L. %A Kimberly J. La Pierre %A A. Risch %A Seabloom, E.W. %A Schütz, Martin %A Steenbock, C. %A Stevens, C.J. %A Fierer, N. %K Fertilization %K shotgun metagenomics %K Soil bacteria %K Soil ecology %K Soil fungi %X

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.

%B Proceedings of the National Academy of Sciences %V 112 %P 10967 - 10972 %G eng %U https://www.pnas.org/content/112/35/10967 %N 35 %M KNZ001789 %R 10.1073/pnas.1508382112 %0 Journal Article %J Nature Plants %D 2015 %T Grassland productivity limited by multiple nutrients %A Fay, P.A. %A Prober, S.M. %A Harpole, W.S. %A Knops, J.M.H. %A J.D. Bakker %A E.T. Borer %A Lind, E.M. %A MacDougall, A.S. %A Seabloom, E.W. %A Wragg, P.D. %A P. Adler %A D.M. Blumenthal %A Buckley, Y.M. %A Chu, C. %A Cleland, E.E. %A Scott. L. Collins %A Davies, K.F. %A G. Du %A Feng, X. %A Firn, J. %A Gruner, D.S. %A Hagenah, N. %A Hautier, Y. %A Heckman, R.W. %A Jin, V.L. %A Kirkman, K.P. %A Klein, J. %A L. Ladwig %A Li, Q. %A McCulley, R.L. %A Melbourne, B.A. %A Mitchell, C.E. %A Joslin L. Moore %A J.W. Morgan %A A. Risch %A schütz, M. %A Stevens, C.J. %A Wedin, D.A. %A Yang, L.H. %X

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.

%B Nature Plants %V 1 %P 15080 %G eng %U https://www.nature.com/articles/nplants201580 %N 7 %M KNZ001788 %R 10.1038/nplants.2015.80 %0 Journal Article %J Ecology Letters %D 2015 %T Plant diversity predicts beta but not alpha diversity of soil microbes across grasslands worldwide %A Prober, S.M. %A Leff, J.W. %A Bates, S.T. %A E.T. Borer %A Firn, J. %A Harpole, W.S. %A Lind, E.M. %A Seabloom, E.W. %A P. Adler %A J.D. Bakker %A E.E Cleland %A DeCrappeo, N.M. %A DeLorenze, E. %A Hagenah, N. %A Hautier, Y. %A Hofmockel, K.S. %A Kirkman, K.P. %A Knops, J.M.H. %A Kimberly J. La Pierre %A MacDougall, A.S. %A McCulley, R.L. %A Mitchell, C.E. %A A. Risch %A Schuetz, M. %A Stevens, C.J. %A Williams, R.J. %A Fierer, N. %X

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.

%B Ecology Letters %V 18 %P 85 -95 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.12381 %M KNZ001678 %R 10.1111/ele.12381 %0 Journal Article %J Nature Communications %D 2015 %T Plant species’ origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands %A Seabloom, E.W. %A E.T. Borer %A Buckley, Y. %A Cleland, E.E. %A Davies, K.F. %A Firn, J. %A Harpole, W.S. %A Hautier, Y. %A Lind, E. %A MacDougall, A.S. %A Orrock, J.L. %A Prober, S.M. %A P. Adler %A Anderson, T.M. %A J.D. Bakker %A L.A. Biederman %A D.M. Blumenthal %A C.S. Brown %A Brudvig, L.A. %A Cadotte, M. %A Chu, C. %A Cottingham, K.L. %A Crawley, M.J. %A Damschen, E.I. %A D’Antonio, C.M. %A CeCrappeo, N.M. %A G. Du %A Fay, P.A. %A Frater, P. %A Gruner, D.S. %A Hagenah, N. %A Hector, A. %A Hillebrand, H. %A Hofmockel, K.S. %A Humphries, H.C. %A Jin, V.L. %A Kay, A.D. %A Kirkman, K.P. %A Klein, J.A. %A Knops, J.M.H. %A Kimberly J. La Pierre %A L. Ladwig %A Lambrinos, J.G. %A Li, Q. %A Li, W. %A Marushia, R. %K Biological sciences %K ecology %K Plant sciences %X

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.

%B Nature Communications %V 6 %P 7710 - %G eng %U https://www.nature.com/articles/ncomms8710 %M KNZ001697 %R 10.1038/ncomms8710 %0 Journal Article %J Global Ecology and Biogeography %D 2014 %T Anthropogenic-based regional-scale factors most consistently explain plot-level exotic diversity in grasslands %A MacDougall, A.S. %A Bennett, J.R. %A Firn, J. %A Seabloom, E.W. %A E.T. Borer %A Lind, E.M. %A Orrock, J.L. %A Harpole, W.S. %A Hautier, Y. %A P. Adler %A Cleland, E. %A Davies, K. %A Melbourne, B. %A Prober, S.M. %A J.D. Bakker %A Fay, P.A. %A Jin, V.L. %A Kendig, A. %A Kimberly J. La Pierre %A Joslin L. Moore %A J.W. Morgan %A Stevens, C.J. %X

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.

%B Global Ecology and Biogeography %V 23 %P 802 - 810 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12157 %N 7 %M KNZ001792 %R 10.1111/geb.12157 %0 Journal Article %J Nature %D 2014 %T Eutrophication weakens stabilizing effects of diversity in natural grasslands %A Hautier, Y. %A Seabloom, E.W. %A E.T. Borer %A P. Adler %A Harpole, W.S. %A Hillebrand, H. %A Lind, E.M. %A MacDougall, A.S. %A Stevens, C.J. %A J.D. Bakker %A Buckley, Y.M. %A Chu, C. %A Scott. L. Collins %A Daleo, P. %A Damschen, E.I. %A Davies, K.F. %A Fay, P.A. %A Firn, J. %A Gruner, D.S. %A Jin, V.L. %A Klein, J.A. %A Knops, J.M.H. %A Kimberly J. La Pierre %A Li, W. %A McCulley, R.L. %A Melbourne, B.A. %A Joslin L. Moore %A O’Halloran, L.R. %A Prober, S.M. %A A. Risch %A Sankaran, M. %A Schuetz, M. %A Hector, A. %K Biodiversity %K Community ecology %K Grassland ecology %X

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.

%B Nature %V 508 %P 521 -525 %G eng %U https://www.nature.com/articles/nature13014 %M KNZ001632 %R 10.1038/nature13014 %0 Journal Article %J Nature %D 2014 %T Herbivores and nutrients control grassland plant diversity via light limitation %A E.T. Borer %A Seabloom, E.W. %A Gruner, D.S. %A Harpole, W.S %A Hillebrand, H. %A Lind, E.M. %A P. Adler %A J. Alberti %A Anderson, T.M. %A J.D. Bakker %A L.A. Biederman %A D.M. Blumenthal %A C.S. Brown %A Brudvig, L.A. %A Buckley, Y.M. %A Cadotte, M. %A Chu, C. %A Cleland, E.E. %A Crawley, M.J. %A Daleo, P. %A Damschen, E.I. %A Davies, K.F. %A DeCrappeo, N.M. %A G. Du %A Firn, J. %A Hautier, Y. %A Heckman, R.W. %A Hector, A. %A HilleRisLambers, J. %A Iribarne, Oscar %A Klein, J.A. %A Knops, J.M.H. %A Kimberly J. La Pierre %A Leakey, A.D.B. %A Li, W. %A MacDougall, A.S. %A McCulley, R.L. %A Melbourne, B.A. %A Mitchell, C.E. %A Joslin L. Moore %A Mortensen, B. %A O'Halloran, L.R. %A Orrock, J.L. %A Pascual, J. %A Prober, S.M. %A Pyke, D.A. %A A. Risch %A Schuetz, M. %A M.D. Smith %A Stevens, C.J. %A L.L. Sullivan %A Williams, R.J. %A Wragg, P.D. %A Wright, J.P. %A Yang, L.H. %B Nature %V 508 %P 517 - 520 %G eng %U https://www.nature.com/articles/nature13144 %N 7497 %M KNZ001793 %R 10.1038/nature13144 %0 Journal Article %J Global Change Biology %D 2013 %T Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness? %A Seabloom, E.W. %A E.T. Borer %A Buckley, Y. %A Cleland, E.E. %A Davies, K. %A Firn, J. %A Harpole, W.S. %A Hautier, Y. %A Lind, E. %A MacDougall, A. %A Orrock, J.L. %A Prober, S.M. %A P. Adler %A J. Alberti %A Anderson, M.T. %A J.D. Bakker %A L.A. Biederman %A D.M. Blumenthal %A C.S. Brown %A Brudvig, L.A. %A Caldeira, M. %A Chu, C. %A Crawley, M.J. %A Daleo, P. %A Damschen, E.I. %A D'Antonio, C.M. %A DeCrappeo, N.M. %A Dickman, C.R. %A G. Du %A Fay, P.A. %A Frater, P. %A Gruner, D.S. %A Hagenah, N. %A Hector, A. %A Helm, A. %A Hillebrand, H. %A Hofmockel, K.S. %A Humphries, H.C. %A Iribarne, O. %A Jin, V.L. %A Kay, A. %A Kirkman, K.P. %A Klein, J.A. %A Knops, J.M.H. %A Kimberly J. La Pierre %A L. Ladwig %A Lambrinos, J.G. %A Leakey, A.D.B. %A Li, Q. %A Li, W. %A McCulley, R. %A Melbourne, B. %A Mitchell, C.E. %A Joslin L. Moore %A J.W. Morgan %A Mortensen, B. %A O'Halloran, L.R. %A Pärtel, M. %A Pascual, J %A Pyke, D.A. %A A. Risch %A Salguero-Gomez, R. %A Sankaran, M. %A Schuetz, M. %A Simonsen, A. %A M.D. Smith %A Stevens, C. %A Sullivan, L. %A Wardle, G.M. %A Wolkovich, E.M. %A Wragg, P.D. %A Wright, J. %A Yang, L. %X

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.

%B Global Change Biology %V 19 %P 3677 - 3687 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12370 %N 12 %M KNZ001790 %R 10.1111/gcb.12370 %0 Journal Article %J Ecology Letters %D 2011 %T Abundance of introduced species at home predicts abundance away in herbaceous communities %A Firn, J. %A Joslin L. Moore %A MacDougall, A.S. %A E.T. Borer %A Seabloom, E.W. %A HilleRisLambers, J. %A Harpole, W.S. %A Cleland, E.E. %A C.S. Brown %A Knops, J.M.H. %A Prober, S.M. %A Pyke, D.A. %A Farrell, K.A. %A J.D. Bakker %A O’Halloran, L.R. %A P. Adler %A Scott. L. Collins %A D’Antonio, C.M. %A Crawley, M.J. %A Wolkovich, E.M. %A Kimberly J. La Pierre %A Melbourne, B.A. %A Hautier, Y. %A J.W. Morgan %A Leakey, A.D.B. %A Kay, A.D. %A McCulley, R. %A Davies, K.F. %A Stevens, C.J. %A Chu, C. %A Holl, K.D. %A Klein, J.A. %A Fay, P.A. %A Hagenah, N. %A Kirkman, K.P. %A Buckley, Y.M. %B Ecology Letters %V 14 %P 274 -281 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1461-0248.2010.01584.x %M KNZ001455 %R 10.1111/j.1461-0248.2010.01584.x