Here we propose two metrics to assess the ecological resilience of
communities based on how changes in the overall abundance of individuals
affect the number of species. The community sensitivity expresses the
rate of change in the log expected number of species with respect to the
log expected total number of individuals, whereas the community
resistance is the proportional reduction in community size that will
reduce the expected number of species by one. Estimates of these metrics
in four bird communities in European deciduous forests using a
stochastic model for the community dynamics revealed large differences
in the resilience to permanent changes of the environment. In
particular, stochastic influences from environmental fluctuations
strongly affected the sensitivity and the resistance caused by area loss
or increased environmental stochasticity. This shows that ecological
resilience is closely related to which processes that most strongly
affect the temporal dynamics of communities.