Extreme Drought in Grasslands Experiment

The  goal of EDGE is to determine the consequences of chronic drought on biodiversity and ecosystem services in grasslands across precipitation and temperature gradients in central North America. Principal Investigators at UNM are Scott Collins and Will Pockman. This is a collaborative research project led by Alan Knapp and Melinda Smith (Colorado State University) and Yiqi Luo (University of Oklahoma). In order to better forecast how entire regions will respond to expected climatic changes, there is a pressing need to understand why ecosystems differ in their sensitivity to changes in climate. This project includes research designed to answer a question of fundamental importance for advancing knowledge of biological processes at large scales: How important are the attributes of ecosystems per se versus the environmental context in which climate is changing in determining ecological responses to climate change at regional scales? To answer this question, a geographically distributed field experiment is being conducted at six sites in NM, CO, WY and KS and the results from this experiment will be used to strengthen an existing process-based terrestrial ecosystem model. With this model, the relative importance of ecosystem attributes versus the environment for determining responses to climate change will be evaluated and then scaling rules for extending site-based knowledge to regional scales will be developed.

Thus far we have constructed the frames for the rainout shelters in our blue grama and black grama sites at SEV, gathered preliminary data on species composition and net primary production and designed our soil CO2, moisture and temperature sensor arrays. Starting in 2013, the experiment will impose be a severe 4-year drought in grasslands arrayed along a rainfall gradient (from desert grassland to mesic tallgrass prairie). Key responses measured will include many related to carbon cycling and budgets and plant biodiversity.