Compositional resistance and successional reversal after
long-term experimental drought in biocrust communities
Abstract
The
effects of severe drought on the stability of dryland ecosystems are
still uncertain and it is unknown whether diversity can buffer changes
in systems that are adapted to water-limitation.
We investigated the effects of
long-term induced drought on the composition and maturity of biological
soil crusts (biocrusts), as well as tested the hypothesis that diversity
promotes stability using compositional resistance as a measure for
ecosystem stability. We surveyed an array of 25 sites in the central
Colorado Plateau, USA, that included plots that received ambient
precipitation and plots that had experienced eight years of
~35% precipitation reduction.
We found that biocrusts can
maintain broad compositional integrity after long-term climate
disturbance. However, biocrust successional reversal still occurred,
with a reduction of later successional constituents and an increase of
early successional cyanobacterial cover. Our findings indicate that
long-term drought could have major impacts on biocrust community
stability.