Exotic success following disturbance explained by weak native resilience and ruderal exotic bias

PEARSON, DEAN E.; ORTEGA, YVETTE K.; EREN, ÖZKAN; VILLARREAL, DIEGO; LEKBERG, YLVA; HIERRO, JOSÉ

JOURNAL OF ECOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Año: 2023

0022-0477

1. Disturbance is a primary driver of exotic plant invasions, but why disturbance commonly favours exotics over natives is unresolved.2. To address this question, we conducted the first biogeographic study of distur- bance across multiple plant species. We experimentally disturbed grasslands and added seeds of 34 plant species to plots in their native range and in two intro- duced ranges that differed in invasibility (susceptibility to invasion) to evaluate recruitment while examining potential influences of resource availability, native community recovery from disturbance (resilience) and life-history traits in local species pools.3. Species pools in the native (donor) range were more strongly skewed towards ruderal taxa than species pools in the introduced ranges. This bias in the donor pool was exacerbated by introduction filters that further selected for ruderal traits, strongly skewing exotic species pools in the introduced ranges towards ruderals. Sown species, which reflected these trait patterns, benefited from dis- turbance universally, but their disturbance response was 10-fold greater in the more invasible introduced range. This result was not explained by nutrient avail- ability, which responded similar to disturbance across ranges. Nor was it driven by background propagule pressure, which was minimal. Rather, the exaggerated disturbance effect in the more invasible introduced range appeared to be driven by weak recovery of the native plant community that allowed ruderal-biased exotics to proliferate.4. Overall,disturbance appearedtofavouredexoticsbecausetheyweremuchmore likely than natives to be ruderal. However, this trait bias only corresponded with an invader advantage in the more invasible range where weak community resil- ience was linked to slow-growing, stress-tolerant natives that failed to rapidly recover space and resources. In contrast, in the less invasible introduced range,highly competitive native perennials quickly filled the disturbance gap, demon-strating high community resilience that appeared to limit invader recruitment.5. Synthesis: Biogeographic influences on local species pools can facilitate invader success following disturbance, but final invasion outcomes are conditioned by native community resilience.