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dynamics of temperate and tropical grassland, forests, and savanna systems in North America, 
Eurasia, and Africa. Spatial heterogeneity in the landscape due to topographic characteristics or due to 
land use factors (e.g., cultivation practices, fire, grazing, etc.) modify nutrient cycling, water and 
energy fluxes, and biogenic trace gas fluxes. Spatially explicit modeling of the landscape patterns can 
be implemented with ecosystem models such as CENTURY or LINKAGES (Parton et 1987, Pastor 
and Post 1988, Schimel et al 1990, Burke et al. 1990). Extrapolation of biogeochemistry to large 
areas requires the coupling of regional models, remote sensing, and geographical information 
systems. 
Future Research 
The complexity of the interactions between global change and biotic systems is tremendous and the 
development of a predictive understanding of the potential impacts of global change is an enormous 
challenge. Research dealing with biogenic trace gas exchange with atmospheric chemistry, biotic 
interactions with energy and water flux to the climate system, impacts of global change on terrestrial 
ecosystems need to be undertaken to meet this challenge. 
The research plan must include explicit consideration of spatial scaling (how to integrate the 
knowledge of ecosystem processes at the plot level to landscapes, regions, and the global scale), 
temporal scaling, geographical distribution of changes, constraints on ecosystem processes, land 
cover and use, and soil properties. 
Developing the means to predict and monitor changes in terrestrial ecosystems is needed to provide 
the necessary inputs to global models of climate and biogeochemistry. In addition, these 
investigations will lead to the capability of predicting changes for regional and local situations. The 
development of a capability to predict responses by terrestrial ecosystems will involve combinations 
of efforts including synthesis of available data, experiments and observations at a number of scales, 
as well as modeling. Models are necessary to develop a predictive capacity, and GCTE is intended to 
lead to the development of a range of models, using a generic model structure. This capability is 
required for two reasons. The primary reason is to predict the consequences of global change for 
ecosystem structure and physiology, since these ecosystem attributes have direct effects on issues 
important to humans including productivity, future land use, and biotic diversity. The second reason 
is to estimate the potential feedbacks of the changes on further atmospheric and climate change. 
References 
Aber, J.D., Wessman, C.A., Peterson, D.L., Melillo, J.M., and Fownes, J.H. 1990. Remote 
sensing of litter and soil organic matter decomposition in forest ecosystems. In: Remote 
Sensing of Biosphere Functioning. Hobbs, R.J. and Mooney, H.A. (eds.). Springer-Verlag, 
New York. p87-103. 
Burke, I. C., D. S. Schimel, C. M. Yonker, W. J. Parton, L. A. Joyce and W. K. Lauenroth. 1990. 
Regional modeling of grassland biogeochemistry using GIS. Landscape Ecology 4:45-54. 
Coughenour, M.B. and W.J. Parton. Integrated models of ecosystem function: a grassland case 
study. IN: B.H. Walker and W.L. Steffen (eds) Global Change and Terrestrial Ecosystems, 
Cambridge University Press (in press). 
Eagleson, P.S. 1986. Stability of tree/grass vegetation systems. In Climatic- Vegetation Interactions. 
Rosenzweig, C. and Dickinson, R. (eds.). Proceedings of a workshop held at