Fungal pathogens increase community temporal stability through species asynchrony regardless of nutrient fertilization.

Abstract

Natural enemies and their interaction with host nutrient availability influence plant population dynamics, community structure, and ecosystem functions. However, the nature in which these factors influence patterns of community stability, as well as the direct and indirect processes underlying that stability, remain unclear. Here, we investigated the separate and interactive roles of fungal/oomycete pathogens and nutrient fertilization on the temporal stability of community biomass and the potential mechanisms using a factorial experiment in an alpine meadow. We found that fungal pathogen exclusion reduced community temporal stability mainly through decreasing species asynchrony, while fertilization tended to reduce community temporal stability through decreasing species stability. However, there was no interaction between pathogen exclusion and nutrient fertilization. These effects were largely due to the direct effects of the treatments on plant biomass, and not due to indirect effects mediated through plant diversity. Our findings highlight the need for a multi-trophic perspective in field studies examining ecosystem stability.