WHAT THE EVIDENCE SAYS
Across 49 riverine macroinvertebrate metacommunities, greater flow intermittence increased aggregation and reduced evenness, producing lower local diversity but steeper species-area relationships and greater compositional differentiation among reaches. Land use altered regional species pools and weakened some of the differentiation created by drying, consistent with homogenization under combined pressures.
WHY IT MATTERS / OUR READ
A reach can lose species without the whole network changing in the same direction. Management that evaluates only local richness can miss spatial turnover and the fact that drying plus land use reorganizes where diversity is held across a river network.
CAVEATS / UNCERTAINTY
The analysis is observational and specific to southeastern France. The intermediate land-use signal is nonlinear and should not be interpreted as evidence that moderate anthropogenic land use is generally beneficial.
SOURCE
Global Change Biology · Original evidence
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