Rodent herbivory and fire differentially affect plant species recruitment based on variability in life history traits

Abstract

AbstractRodent consumers can have strong top‐down effects on plant community development via seed predation, but their influence on seedling recruitment and how it varies depending on disturbance history and plant traits are largely unknown. Over a two‐year period, we experimentally tested the influence of rodents and fire on seedling survival of 14 plant species with contrasting growth forms and life history traits in the Great Basin Desert. Seedling survival was dramatically increased by rodent exclusion and fire and was greater in 2013 than 2012. Rodent abundance was an order of magnitude lower in 2013 than 2012 and across both years showed a negative linear relationship with mean seedling survival of all 14 plant species (R2 = −0.62). There was strong variability in plant species sensitivity to rodent herbivory with a more than 10‐fold difference in mortality risk between the most sensitive species and the most resistant species and a high degree of variability in survival among all species. Mortality risk of forb species was double that of grass species and there was a trend toward higher mortality of native species compared to introduced species. The results suggest that rodent herbivory may be an important determinant of plant community assembly in desert ecosystems with plant life history strategies and growth form traits serving as important survival filters. Post‐fire environments and low rodent years likely provide windows of opportunity for greater seedling recruitment due to a release from rodent herbivory pressure.