The combined effect of waterlogging, extractable P and soil pH on α-diversity: a case study on mesotrophic grasslands in the UK

Developing a strategy for evidence-based conservation is often problematic where a given habitat is found on relatively few small sites. Here, we investigate the important environmental variables that control species alpha-diversity in wet mesotrophic grasslands in lowland England. We analysed data on species richness and three soils variables from 10 mesotrophic grasslands to test the following hypothesis: is species diversity related to these soil factors, and if so, which is the most important? Generalised linear modelling was used to derive minimum adequate models of these relationships. The analysis identified degree of waterlogging and its interaction with both soil available phosphorus and soil pH as significant. Species diversity decreased with increasing waterlogging and available phosphorus. If species richness is to be conserved in these mesotrophic grasslands, it would be best done by maintaining low levels of waterlogging (0-1 m weeks), and low available phosphorus concentrations (< 10 mu g P g(-1)). However, this approach may predicate against specialist wetland species. Our results will help develop sound conservation strategies for these mesotrophic grasslands, and points the way for further investigative research.