|Jennerette, G. - UNIVERSITY OF ARIZONA|
|Huxman, T. - UNIVERSITY OF ARIZONA|
Submitted to: Functional Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2008
Publication Date: October 21, 2008
Citation: Jennerette, G.D., Scott, R.L., Huxman, T.E. 2008. Whole ecosystem metabolic pulses following precipitation events. Functional Ecology. 22:924-930. doi: 10.1111/j.1365-2435.2008.01450.x Interpretive Summary: Carbon dioxide (CO2) concentrations in the atmosphere have risen dramatically since the start of the Industrial Revolution. There is major concern about how this rise in CO2 has and will affect global climate. All ecosystems take in and release CO2 and so there has also been a large research effort to understand how these CO2 increases will affect and modify the cycling of carbon dioxide within ecosystems. This study developed a method to separate measurements of total ecosystem carbon dioxide exchange into carbon dioxide release (respiration) and uptake (photosynthesis) and applied this method to a data from a network of CO2 flux measurement sites in southern Arizona. Results indicate that the influence of precipitation on respiration varies depending on landscape position and ecosystem type. Therefore, future changes in precipitation patterns associated with global warming will likely result in widely variable ecosystem responses in CO2 cycling in this region, and future research efforts will seek to better understand how ecosystem characteristics give rise to these variable effects.
Technical Abstract: We evaluated the applicability of an ecosystem metabolic ecological theory for understanding the carbon exchange characteristics of woody and grass dominated communities in both riparian and upland landscape positions in southern AZ, USA. The quantitative theory presented here describes a generic and low-dimensional approach to characterizing the dependence of ecosystem metabolism on both temperature and precipitation. We developed models of ecosystem metabolism associated with wet and dry periods in order to evaluate the effects of individual precipitation events in time. At all of the sites, the 24 hour dry-time (inter-rainfall pulse period) temperature-sensitivity model underestimated nighttime carbon fluxes from these ecosystems immediately following a precipitation event. The upscaled precipitation effects contributed to between 2.3% and 33% of the estimated annual ecosystem metabolism among these sites, depending on landscape position and community type. Extensions of low-dimensional but frequently updated ecosystem models such as the one presented will contribute to more effective learning about ecological dynamics by coupling quantitative theory with the growing environmental sensing data streams.