![Numerical Terradynamic Simulation Group](../../assets/md5images/e2704605acc69be5dc55fb0c9fde1136.gif)
Document Type
Article
Publication Title
Ecology
Publication Date
4-1993
Volume
74
Issue
3
First Page
792
Last Page
797
Abstract
A computer model of forest growth and ecosystem processes is presented. The model, HYBRID, is derived from a forest gap model, an ecosystem process model, and a photosynthesis model. In HYBRID individual trees fix and respire carbon, and lose water daily; carbon partioning occurs at the end of each year. HYBRID obviates many of the linitations of both gap models and ecosystem process models. The growth equations of gap models are replaced with functionally realistic equations and processes for carbon fixation and partitioning, resulting in a dynamic model in which competition and physiology play important roles. The model is used to predict ecosystem processes and dynamics in oak forests in Knoxville, Tennessee (USA), and pine forests in Missoula, Montana (USA) between the years 1910 and 1986. The simulated growth of individual trees and the overall ecosystems—level processes are very similiar to observations. A sensitivity analysis performed for these sites showed that predictions of net primary productivity by HBRID are most sensitive to the ratio of CO2 partial pressure between inside the leaf and the air, relative humidity, ambient CO2 partial pressure, precipitation, air temperature, tree allometry, respiration parametes, site soil water capacity, and a carbon storage parameter.
Keywords
ecosystem process model, forest, gap model.leaf area index, modeling, Pinus contorta, productivity, Quercus alba, resperation, sapwood, storage, tree
DOI
http://dx.doi.org/10.2307/1940806
Rights
© 1993 The Ecological Society of America
Recommended Citation
Friend, A. D., Schugart, H. H. and Running, S. W. (1993), A Physiology-Based Gap Model of Forest Dynamics. Ecology, 74: 792–797. doi:10.2307/1940806