Aboveground production and species richness of annuals in Chihuahuan Desert grassland and shrubland plant communities

We found that species richness in summer was significantly correlated with summer precipitation and summer soil moisture in both communities, but summer ANPP was significantly correlated with summer precipitation and soil moisture only in shrubland. However, richness and ANPP of winter annuals were significantly correlated with winter precipitation and winter soil moisture in shrubland and grassland. Our results demonstrate that temporal variation in rainfall can be as important as annual total amounts for plant performance, and that response to temporal dynamics varies among species but not between grass- and shrub-dominated communities. We conclude that desert annuals provide a highly dynamic system for understanding the processes that influence plant species composition and abundance, and that desert annual systems will likely be highly impacted by shrub encroachment along with increases in precipitation variability as a consequence of anthropogenic climate change.