This project will investigate and contrast the likely responses of boreal evergreen forests, temperate deciduous forests, and temperate grasslands to changes in the global environmental over 1-50 years. The environmental changes of interest include changes in the CO2 concentration of the atmosphere, changes in global surface temperature, changes in atmospheric N deposition, and possibly changes in moisture and cloudiness. "Process-functional" approach will be utilized this research, as opposed to a "population-community" approach. The focus is on ecosystem-level processes and functions such as gross and net primary productivity, net ecosystem productivity, decomposition, and net mineralization. Specifically, it is proposed to investigate and contrast: 1) how the initial amounts and distributions of C, N, and P in these three different ecosystem types affect the ecosystem-level responses to environmental change, and 2) how the amounts, distributions, and flux rates of C, N, and P change in response to changes in the environment. The analytical procedures developed here should be applicable to other major terrestrial ecosystem types, as well. The proposed research is important because it will help 1) to anticipate the relative impacts of global change on various regions of the earth, 2) to interpret changes in individual ecosystems as they arise, and 3) to better understand the function of the individual ecosystems. The goal of comparing ecosystem types requires that the "process- functional" aspects of different ecosystems be analyzed from a common perspective and with identical units. To do this a computer model will be developed that incorporates the important components, processes, and linkages present in all terrestrial ecosystems. By parameterizing this model for contrasting ecosystems, differences detected between ecosystems can be more clearly attributed to the ecosystems themselves and not to differences in the models used to describe them. The research team for this project is excellent and brings a long history of productive collaboration to bear upon the work. Institutional accommodations and facilities are excellent.
