Variation in species pools can affect plant diversity, but it remains unclear whether the
magnitude of the response varies because of resource availability, community invasibility or
other environmental factors, and whether colonization along environmental gradients
reflects niche‐based species sorting or neutral processes. 2. We hypothesized that
unimodal diversity–productivity patterns in grasslands are dependent on species pools, with
peak richness occurring at intermediate productivity due to species sorting associated with …