Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2008
Publication Date: 6/12/2008
Citation: Fay, P.A., Kaufman, D.M., Nippert, J.B., Carlisle, J.D., Harper, C.W. 2008. Changes in grassland ecosystem function due to extreme rainfall events: implications for responses to climate change. Global Change Biology. 14:1600-1608. Interpretive Summary: Extreme precipitation patterns, marked by long dry periods interspersed with heavy rainfall events, are expected to increase with climate change and are likely to impact many aspects of the natural and human systems on which we rely for food, fiber, and clean air and water, including their capacity to store carbon. We conducted a study in grassland which showed that more extreme precipitation regimes could result in increased carbon sequestration and potentially alter the effects of elevated atmospheric CO2. All facets of climate change must be considered in order to understand how ecosystems will respond to future climate.
Technical Abstract: Climate change driven by increasing atmospheric CO2 concentrations is causing measurable changes in precipitation patterns. Most climate change scenarios forecast continuing increases in extreme precipitation patterns for North American terrestrial ecosystems, manifest as larger precipitation events separated by longer dry periods, with still uncertain implications for key processes controlling terrestrial ecosystem structure and function. Changes in the size of precipitation events may cause differential responses in the processes controlling the uptake and loss of C, and therefore could alter carbon sequestration in terrestrial ecosystems. Here we show that more extreme precipitation patterns (longer intervals between events combined with larger events) shifted experimental grasslands toward greater net uptake of C, and also made C fluxes less responsive to variation in event size, changes which could lead to increased C-sequestration under more extreme precipitation regimes. These results have important implications for terrestrial ecosystem responses to climate change. More extreme precipitation regimes may reinforce increases in C-sequestration expected to result from increasing atmospheric [CO2], but may also lower plant water status and productivity. Thus, these results highlight the need for improved forecasts of precipitation pattern as well as quantity and field experiments that manipulate CO2, temperature, and precipitation in combination in order to improve forecasts of ecosystem carbon dynamics.