Forest Modeling

(Return to the Forests page)

The Zelig gap model (version Facet) acts as an integrative framework for coupling physical template, disturbance, and biotic processes, and is validated with both historical and modern forest/climate reconstructions. It can be successfully scaled up (MetaFor) to replicate actual distributions of Sierran tree species along elevational gradients (Urban et al. In press). 

Our first phase of research suggested that recruitment and death rates play a much greater role than growth rates in driving forest dynamics. This contradicts some of the basic assumptions of many forest dynamics models. We now must verify our preliminary results by quantifying the relative importances of demographic rates and growth rates, on a species-by-species basis, for comparison with Zelig outputs and in a format useful for modifying the model, as needed.

While our earlier modeling efforts mostly were at the scale of forest stands (e.g., 0.1-10 ha), we will now scale up to landscapes (10,000-100,000 ha). Spatially-explicit models of landscape sensitivity (e.g., figure 1.) can help land managers focus monitoring efforts on those areas most likely to respond to climatic change, and predict which portions of the landscape are highest priority for mitigation efforts.

Figure 1. False-color composite image of Kaweah Basin in Sequoia National Park, illustrating relative sensitivity to climatic change. Red scales with increasing sensitivity to temperature change; blue, to change in precipitation. Green scales with increasing uncertainty due to the local influence of topographic drainage on soil moisture. Thus, magenta colors those sites that are most sensitive to variability in temperature and precipitation.

Dean Urban Assistant Professor Nicholas School of the Environment Duke University Durham, NC 27708 deanu@pinus.env.duke.edu

Selected Publications:

Urban, D.L., M.F. Acevedo, and S.L. Garman. In press. Scaling fine-scale processes to large-scale patterns using models derived from models: meta-models. In W. Baker and D. Mladenoff (eds), Spatial modeling of forest landscape change: approaches and applications. Cambridge University Press.

Keitt, T.H., D.L. Urban, and B.T. Milne. 1997. Detecting critical scales in fragmented landscapes. Conservation Ecology 1:4. [URL=http://www.consecol.org/Journal/vol1/iss1/art4 (online)]

Acevedo, M., D.L. Urban, and M. Ablan. 1995. Transition and gap models of forest dynamics. Ecological Applications 5:1040-1055.

Urban, D.L., M.E. Harmon, and C.B. Halpern. 1993. Potential response of Pacific Northwestern forests to climatic change: effects of stand age and initial composition. Climatic Change 23:247-266.

Coffin, D.P., and D.L. Urban. 1993. Implications of natural-history traits to ecosystem dynamics: comparison of a grassland and forest. Ecological Modeling 67:147-178.

Urban, D.L. and H.H. Shugart. 1992. Individual-based models of forest succession. Pages 249-292 in D.C. Glenn-Lewin, R.K. Peet, and T.T. Veblen (eds), Plant Succession: Theory and Prediction. Chapman and Hall, London.

Urban, D.L., G. Bonan, T.M. Smith, and H.H. Shugart. 1991. Spatial applications of gap models. Forest Ecology and Management 42:95-110.

Shugart, H.H., and D.L. Urban. 1989. Factors affecting the relative abundance of forest tree species. Pages 249-273 in P.J. Grubb and J.B. Whittaker (eds.), Toward a More Exact Ecology. Jubilee Symposium of the British Ecological Society. Blackwell, Oxford.

Smith, T.M., and D.L. Urban. 1988. Scale and resolution of forest structural pattern. Vegetatio 74:143-150.

Urban, D.L., R.V. O'Neill, and H.H. Shugart. 1987. Landscape ecology. BioScience 37:119-127.

(Return to the Forests page)

Comments to: webmaster@werc.usgs.gov
URL: http://www.werc.usgs.gov/sngc/forest_modeling.htm

This page last updated: Thursday, March 22, 2007