title: Plant invasions differentially affected by diversity and dominant species in native- and exotic-dominated grasslands.
abstract: Plant invasions are an increasingly serious global concern, especially as the climate changes. Here, we explored how plant invasions differed between native- and novel exotic-dominated grasslands with experimental addition of summer precipitation in Texas in 2009. Exotic species greened up earlier than natives by an average of 18 days. This was associated with a lower invasion rate early in the growing season compared to native communities. However, invasion rate did not differ significantly between native and exotic communities across all sampling times. The predictors of invasion rate differed between native and exotic communities, with invasion being negatively influenced by species richness in natives and by dominant species in exotics. Interestingly, plant invasions matched the bimodal pattern of precipitation in Temple, Texas, and did not respond to the pulse of precipitation during the summer. Our results suggest that we will need to take different approaches in understanding of invasion between native and exotic grasslands. Moreover, with anticipated increasing variability in precipitation under global climate change, plant invasions may be constrained in their response if the precipitation pulses fall outside the normal growing period of invaders.
authors.affiliation: Department of Ecology, Evolution and Organismal Biology Iowa State University Ames Iowa 50011.
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.affiliation: Grassland, Soil and Water Research Laboratory USDA-ARS Temple Texas 76502.
authors.forename: H Wayne
authors.initials: HW
authors.lastname: Polley
authors.affiliation: Department of Ecology, Evolution and Organismal Biology Iowa State University Ames Iowa 50011.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Hofmockel
authors.affiliation: Department of Biology Monmouth University 400 Dedar Avenue West Long Branch New Jersey 07764.
authors.forename: Pedram P
authors.initials: PP
authors.lastname: Daneshgar
authors.affiliation: Department of Ecology, Evolution and Organismal Biology Iowa State University Ames Iowa 50011.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Wilsey
keywords: Climate change; dominant species; irrigation, precipitation pattern; native and exotic grasslands; phenology; plant invasions; species richness