Determinants of plant establishment success in a multispecies introduction experiment with native and alien species

Determinants of plant establishment and invasion are a key issue in ecology and evolution. Although establishment success varies substantially among species, the importance of species traits and extrinsic factors as determinants of establishment in existing communities has remained difficult to prove in observational studies because they can be confounded and mask each other. Therefore, we conducted a large multispecies field experiment to disentangle the relative importance of extrinsic factors vs. species characteristics for the establishment success of plants in grasslands. We introduced 48 alien and 45 native plant species at different seed numbers into multiple grassland sites with or without experimental soil disturbance and related their establishment success to species traits assessed in five independent multispecies greenhouse experiments. High propagule pressure and high seed mass were the most important factors increasing establishment success in the very beginning of the experiment. However, after 3 y, propagule pressure became less important, and species traits related to biotic interactions (including herbivore resistance and responses to shading and competition) became the most important drivers of success or failure. The relative importance of different traits was environment-dependent and changed over time. Our approach of combining a multispecies introduction experiment in the field with trait data from independent multispecies experiments in the greenhouse allowed us to detect the relative importance of species traits for early establishment and provided evidence that species traits—fine-tuned by environmental factors—determine success or failure of alien and native plants in temperate grasslands.

Experimental plant communities develop phylogenetically overdispersed abundance distributions during assembly

The importance of competition between similar species in driving community assembly is much debated. Recently, phylogenetic patterns in species composition have been investigated to help resolve this question: phylogenetic clustering is taken to imply environmental filtering, and phylogenetic overdispersion to indicate limiting similarity between species. We used experimental plant communities with random species compositions and initially even abundance distributions to examine the development of phylogenetic pattern in species abundance distributions. Where composition was held constant by weeding, abundance distributions became overdispersed through time, but only in communities that contained distantly related clades, some with several species (i.e., a mix of closely and distantly related species). Phylogenetic pattern in composition therefore constrained the development of overdispersed abundance distributions, and this might indicate limiting similarity between close relatives and facilitation/complementarity between distant relatives. Comparing the phylogenetic patterns in these communities with those expected from the monoculture abundances of the constituent species revealed that interspecific competition caused the phylogenetic patterns. Opening experimental communities to colonization by all species in the species pool led to convergence in phylogenetic diversity. At convergence, communities were composed of several distantly related but species-rich clades and had overdispersed abundance distributions. This suggests that limiting similarity processes determine which species dominate a community but not which species occur in a community. Crucially, as our study was carried out in experimental communities, we could rule out local evolutionary or dispersal explanations for the patterns and identify ecological processes as the driving force, underlining the advantages of studying these processes in experimental communities. Our results show that phylogenetic relations between species provide a good guide to understanding community structure and add a new perspective to the evidence that niche complementarity is critical in driving community assembly.

Inventory of seeds and plants imported / U.S. Department of Agriculture, Bureau of Plant Industry.

48-61, 1921-1922

Inventory of seeds and plants imported / U.S. Department of Agriculture, Bureau of Plant Industry.

37-47

Circular / U.S. Department of Agriculture, Bureau of Plant Industry.

no. 73-104

Circular / U.S. Department of Agriculture, Bureau of Plant Industry.

no. 105-119

Circular / U.S. Department of Agriculture, Bureau of Plant Industry.

no. 42-72

Crash protection systems for handicapped school and transit bus occupants. Volume III: appendices A, B, C and D. Interim report.

National Highway Traffic Safety Administration, Washington, D.C.

Lessons learned in the D.C. public schools : hearing before the Subcommittee on Oversight of Government Management, Restructuring, and the District of Columbia of the Committee on Governmental Affairs, United States Senate, One Hundred Fifth Congress, second session, March 9, 1998.

Shipping list no.: 98-0336-P.

Transformations of heavy metals and plant nutrients in dredged sediments as affected by oxidation reduction potential and pH : final report /

"May 1977."

Plant closings: information on advance notice and assistance to dislocated workers.

Mode of access: Internet.

Environmental factors in coal liquefaction plant design /

Presented at EPA Symposium on Environmental Aspects of Fuel Conversion Technology, May 14, 1974.

An appraisal of OBE-SEC estimates of plant and equipment expenditures, 1947-1958 /

"Printed October 1959. Reprinted May 1961 with minor revisions."