Although scientists have learned much in the past 20 years about how individual ecosystems are likely to respond to climate change, extending this knowledge to regional and continental scales has been a far greater challenge. At these larger spatial scales, both the environment and the attributes of ecosystems vary dramatically. For example, in the central US, there are strong temperature and rainfall gradients from Texas to North Dakota and the dry plains of Colorado to eastern Kansas, and the types of grasslands differ as well (from short grasslands in the west to tall grasslands in the east). 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 vs. 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 will be 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. The experiment imposed will be a severe multi-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.
The project has a number of broader impacts including enhancing existing terrestrial ecosystem modeling approaches, and conducting a field experiment that will provide a platform for others in the scientific community to conduct additional research activities. A project website will make products (datasets, key results, papers, models) available to the scientific community and general public. Research will occur on federal lands and at a number of other research stations where outreach programs are in place, allowing results to be shared with a wide range of stakeholders. The project is also designed to provide training opportunities for numerous graduate and undergraduate students. Because this study is unique in its spatial extent and combination of field and modeling approaches, the collaborative training opportunities available to students differs substantially from traditional degree programs.
