Nutrient supply shifts successional paths but not speed of grassland
recovery from disturbance
Abstract
Disturbance and environmental change may cause communities to converge
to a steady state, diverge towards multiple alternative states, or
remain in long-term transience. Yet, empirical tests of these
successional trajectories are rare, especially in systems experiencing
multiple concurrent anthropogenic drivers of change. We compared
competing models of succession in grassland communities subjected to
disturbance and nitrogen fertilization using data from a long-term
(22-year) experiment. Regardless of disturbance, after a decade
communities settled on equilibrium states largely determined by resource
availability, with species turnover declining as communities approached
dynamic equilibria. Species favored by the disturbance were those that
eventually came to dominate the highly fertilized plots. Furthermore,
disturbance made successional pathways more direct, revealing an
important interaction effect between nutrients and disturbance as
drivers of community change. Our results underscore the dynamical nature
of grassland succession, demonstrating how community properties such as
beta-diversity change through transient and equilibrium states.