The impact of environmental fluctuation on species coexistence is
critical for understanding biodiversity loss and the ecological impacts
of climate change. Yet, determining how properties like the intensity,
frequency, or duration of environmental variation influence species
coexistence remains challenging because we lack a theoretical framework
that generates testable predictions in realistic biological systems.
Here, we model the impact of environmental change at different temporal
scales on species coexistence in nonequilibrium systems by employing the
concept of performance curves to incorporate niche differences within a
stochastic Lotka-Volterra framework. We discover that short- and
long-term environmental variability have contrasting effects on species
coexistence, such that short-term variation favors species coexistence,
whereas long-term variation promotes competitive exclusion.
Consequently, we show the complex set of environmental variability and
species coexistence relationships found in previous studies can all be
synthesized within a general framework by explicitly considering both
long- and short-term environmental variation.