Distinct invasion strategies operating within a natural annual plant system.

Alien plant species are known to have a wide range of impacts on recipient communities, from resident species' exclusions to coexistence with resident species. It remains unclear; however, if this variety of impacts is due to different invader strategies, features of recipient communities or both. To test this, we examined multiple plant invasions of a single ecosystem in southwestern Australia. We used extensive community data to calculate pairwise segregation between target alien species and many co-occurring species. We related segregation to species' positions along community trait hierarchies and identified at least two distinct invasion strategies: 'exploiters' which occupy high positions along key trait hierarchies and reduce local native species diversity (particularly in nutrient-enriched situations), and 'coexisters' who occupy intermediate trait positions and have no discernable impact on native diversity. We conclude that trait hierarchies, linked to measures of competition, can provide valuable insights about the processes driving different invasion outcomes.

[1]  D. Bates,et al.  Linear Mixed-Effects Models using 'Eigen' and S4 , 2015 .

[2]  R. Hobbs,et al.  Climate moderates release from nutrient limitation in natural annual plant communities , 2015 .

[3]  Nathan J B Kraft,et al.  Functional trait differences and the outcome of community assembly: an experimental test with vernal pool annual plants , 2014 .

[4]  Amy E. Kendig,et al.  Anthropogenic-based regional-scale factors most consistently explain plot-level exotic diversity in grasslands , 2014 .

[5]  Richard J Hobbs,et al.  Specific leaf area responses to environmental gradients through space and time. , 2014, Ecology.

[6]  Peter B Adler,et al.  Trait-based tests of coexistence mechanisms. , 2013, Ecology Letters.

[7]  P. Reich,et al.  New handbook for standardised measurement of plant functional traits worldwide , 2013 .

[8]  J. HilleRisLambers,et al.  Rethinking Community Assembly through the Lens of Coexistence Theory , 2012 .

[9]  R. Kadmon,et al.  Functional trade-offs increase species diversity in experimental plant communities. , 2012, Ecology letters.

[10]  J. Maron,et al.  Seed size and provenance mediate the joint effects of disturbance and seed predation on community assembly , 2012 .

[11]  J. Soussana,et al.  Habitat filtering and niche differentiation jointly explain species relative abundance within grassland communities along fertility and disturbance gradients. , 2012, The New phytologist.

[12]  D. Coomes,et al.  Competitive interactions between forest trees are driven by species' trait hierarchy, not phylogenetic or functional similarity: implications for forest community assembly. , 2012, Ecology letters.

[13]  D. Norton,et al.  Which plant traits determine abundance under long‐term shifts in soil resource availability and grazing intensity? , 2012 .

[14]  Evan Weiher,et al.  Advances, challenges and a developing synthesis of ecological community assembly theory , 2011, Philosophical Transactions of the Royal Society B: Biological Sciences.

[15]  S. Prober,et al.  Resource heterogeneity and persistence of exotic annuals in long-ungrazed Mediterranean-climate woodlands , 2011, Biological Invasions.

[16]  I. Jamieson,et al.  Multimodel inference in ecology and evolution: challenges and solutions , 2011, Journal of evolutionary biology.

[17]  M. Mayfield,et al.  Opposing effects of competitive exclusion on the phylogenetic structure of communities. , 2010, Ecology letters.

[18]  H. Muller‐Landau.  The tolerance–fecundity trade-off and the maintenance of diversity in seed size , 2010, Proceedings of the National Academy of Sciences.

[19]  M. Fischer,et al.  A meta-analysis of trait differences between invasive and non-invasive plant species. , 2010, Ecology letters.

[20]  Janneke HilleRisLambers,et al.  The importance of niches for the maintenance of species diversity , 2009, Nature.

[21]  B. Gilbert,et al.  Plant invasions and the niche , 2009 .

[22]  Andy Hector,et al.  Competition for Light Causes Plant Biodiversity Loss After Eutrophication , 2009, Science.

[23]  A. Gelman.  Scaling regression inputs by dividing by two standard deviations , 2008, Statistics in medicine.

[24]  Steward T. A. Pickett,et al.  Plant litter: Its dynamics and effects on plant community structure , 2008, The Botanical Review.

[25]  W. Stanley Harpole,et al.  Grassland species loss resulting from reduced niche dimension , 2007, Nature.

[26]  Alan Hastings,et al.  Invasion in a heterogeneous world: resistance, coexistence or hostile takeover? , 2007, Ecology letters.

[27]  J. HilleRisLambers,et al.  Climate variability has a stabilizing effect on the coexistence of prairie grasses , 2006, Proceedings of the National Academy of Sciences.

[28]  D. Tilman,et al.  Non-neutral patterns of species abundance in grassland communities. , 2005, Ecology letters.

[29]  R. Standish,et al.  Legacy of Land-Use Evident in Soils of Western Australia’s Wheatbelt , 2006, Plant and Soil.

[30]  A. MacDougall,et al.  ARE INVASIVE SPECIES THE DRIVERS OR PASSENGERS OF CHANGE IN DEGRADED ECOSYSTEMS , 2005 .

[31]  M. Westoby,et al.  Small‐seeded species produce more seeds per square metre of canopy per year, but not per individual per lifetime , 2004 .

[32]  L. Stone,et al.  The checkerboard score and species distributions , 1990, Oecologia.

[33]  K. Gross,et al.  Experimental studies of seed predation in old-fields , 1984, Oecologia.

[34]  C. Daehler.  PERFORMANCE COMPARISONS OF Co-OCCURRING NATIVE AND ALIEN INVASIVE PLANTS: Implications for Conservation and Restoration , 2003 .

[35]  Cynthia S. Brown,et al.  Community assembly and invasion: An experimental test of neutral versus niche processes , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[36]  M. Westoby,et al.  ECOLOGICAL STRATEGIES : Some Leading Dimensions of Variation Between Species , 2002 .

[37]  P. Chesson,et al.  Community ecology theory as a framework for biological invasions , 2002 .

[38]  P. Chesson.  Mechanisms of Maintenance of Species Diversity , 2000 .

[39]  James H. Brown,et al.  CONSTRAINTS OF SEED SIZE ON PLANT DISTRIBUTION AND ABUNDANCE , 2000 .

[40]  D. Simberloff,et al.  BIOTIC INVASIONS: CAUSES, EPIDEMIOLOGY, GLOBAL CONSEQUENCES, AND CONTROL , 2000 .

[41]  A. Ghani,et al.  Tansley Review No. 110.: Numerical and physical properties of orchid seeds and their biological implications. , 2000, The New phytologist.

[42]  C. J. West,et al.  Naturalization and invasion of alien plants: concepts and definitions , 2000 .

[43]  Colin J. Yates,et al.  Temperate eucalypt woodlands: A review of their status, processes threatening their persistence and techniques for restoration , 1997 .

[44]  Paul A. Keddy,et al.  Assembly and response rules: two goals for predictive community ecology , 1992 .