|Huxman, T. - UNIVERSITY OF ARIZONA|
Submitted to: Biodiversity & Management of the Madrean Archipelago Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 1, 2005
Publication Date: September 1, 2005
Citation: Scott, R.L., Huxman, T.E. 2005. Comparing ecosystem water and carbon exchange across a riparian mesquite invasion gradient. Proc. Biodiversity and Management of the Madrean Archipelago II Conf., Connecting Mountain Islands and Desert Seas, May 11-14, Tucson, AZ, pp. 320-323. Interpretive Summary: Encroachment by mesquite is arguably the most pervasive and temporally dynamic land-cover change in the southwestern US. It is important to understand how this on-going change in vegetation will affect water and nutrient cycling in order to predict the outcomes of this change on society. We investigated the consequences of mesquite encroachment on water and carbon exchange in a Southwestern riparian area. Results suggest that the deep roots of mesquite will lead to an increase in ecosystem water use as the invading mesquites mature in former grasslands. This ability of mesquite to rely on stable groundwater sources rather than precipitation enhanced net carbon uptake in the dry periods and net carbon loss in rainy periods. These preliminary results suggest that mesquite encroachment in riparian areas will increase groundwater use and lead to additional carbon sequestration.
Technical Abstract: Ecosystem water and carbon fluxes were monitored over a riparian grassland, mesquite-invaded grassland, and mesquite woodland to understand the consequences of woody plant encroachment. Water use and carbon gain were largest at the woodland site. Results suggest that the deep roots of mesquite will lead to a decoupling of ecosystem water sources as the invading mesquites mature in former grasslands. The ability of mesquite to rely on stable groundwater sources rather than precipitation enhanced net carbon uptake in the dry periods and net carbon loss in rainy periods. These results highlight the important role that water sources and ecosystem morphology play on controlling water and carbon balances in semiarid areas.