HR: 17:00h
AN: B54B-05    [Abstracts]
TI: Patterns of Nonlinearity in Ecosystem Carbon and Water Dynamics in response to Gradual Changes in Temperature, CO2, and Precipitation: Modeling Analysis
AU: * Zhou, X
EM: zxuhui14@ou.edu
AF: University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, United States
AU: Weng, E
EM: esweng@ou.edu
AF: University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, United States
AU: Luo, Y
EM: yluo@ou.edu
AF: University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, United States
AB: It is commonly acknowledged that ecosystem responses to global climate change are nonlinear. However, patterns of the nonlinearity have not been well characterized on ecosystem carbon and water processes. We used a terrestrial ecosystem (TECO) model to examine nonlinear patterns of ecosystem responses to changes in temperature, CO2, and precipitation individually or in combination. The TECO model was calibrated against experimental data obtained from a grassland ecosystem in central USA and ran for 100 years with gradual change at 252 different scenarios. We primarily used the 100th-year results to explore nonlinearity of ecosystem responses. Variables examined in this study are net primary productivity (NPP), heterotrophic respiration (Rh), net ecosystem carbon exchange (NEE), runoff, and evapotranspiration (ET). Our modeling results show that nonlinear patterns were parabolic, asymptotic, and threshold-like in response to temperature, CO2, and precipitation anomalies, respectively, for NPP, NEE, and Rh. Runoff and ET exhibited threshold-like pattern in response to both temperature and precipitation anomalies but were less sensitive to CO2 changes. Ecosystem responses to combined temperature, CO2, and precipitation anomalies considerably differed from the responses to individual factors in terms of response patterns and/or critical points of nonlinearity. Our results suggest that nonlinear patterns in response to multiple global change factors were diverse and were considerably affected by combined climate anomalies on ecosystem carbon and water processes. The diverse response patterns in nonlinearity have profound implications for both experimental design and theoretical development.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1630 Impacts of global change (1225)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting