Response of introduced and native grassland species to climate variability, eutrophication and their interactions. A multi-site comparison

HABACUC FLORES-MORENO; ERIC M. LIND; ERIC W. SEABLOOM; PETER B. REICH; LAUREN L. SULLIVAN; LAURA YAHDJIAN; LARA REICHMANN

Baltimore

Congreso; 100th Annual Meeting of the Ecological Society of America; 2015

Ecological Society of America

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 nonnative species richness and decreased native species richness, with these effects dampened in armer or wetter sites. Eutrophication also altered the timescale 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 timescale of the links between climate and compositional change.