Temperature and rainfall greatly influence the structure and function of grasslands, making them particularly vulnerable to projected climate changes. In the Central Plains mean temperatures are expected to increase and rainfall patterns are predicted to become more variable and extreme, with an increased frequency of large rainfall events and extended inter-rainfall droughts. The ecological consequences of these changes are difficult to predict. This LTREB project addresses the consequences of potential climate change by supporting the long-term manipulation of rainfall and temperature in a unique experimental facility (the Rainfall Manipulation Plots, RaMPs). For seven years, we have been assessing the impacts of altered rainfall patterns (larger rain events with longer inter-rainfall droughts, but no change in total precipitation amount) in replicated, intact grassland plots. Our central hypothesis is that changes in the timing of rainfall events will significantly alter temporal patterns and depth distributions of soil moisture, with long-term consequences for plant, community and ecosystem processes. In 2003 we added a warming treatment to assess the consequences of a combination of more extreme rainfall patterns (increased climatic variability) and increased temperatures (increased climatic mean). The interactive effects of more extreme rainfall patterns and warmer temperatures are expected to be complex, but will be critical for predicting the sustainability of grassland resources and ecosystem services under future climate scenarios. This LTREB project will support the training of undergraduate and graduate students, provide new data to the scientific community, and inform the general public on the importance of global change research.
