Individual-based simulation models for forest succession and management
Individual-based forest models simulate forest dynamics on the basis of establishment, growth and death of individual trees. This paper attempts to review and compare two major types of individual-based forest models: growth-yield and gap models. Although the two types of models share some similar features, they differ in model structure and data requirements and play several complementary roles. Growth-yield models are used by foresters to assist timber production and evaluate growth and yield of one to several commercial timber species in managed forests, while gap models are generally developed by ecologists to explore ecological mechanisms and patterns of structure and functional dynamics in natural forest ecosystems. Site-specific environmental and species information is necessary for constructing growth-yield models while gap models require species-specific biological information of individual trees and site-specific environmental data. The growth-yield models are more diverse in terms of model structure. In contrast, gap models belong to the same genealogy and later gap models are ultimately derived from the earliest one although they may vary in detail. In the future, we expect to see more individual-based hybrid models which integrate gap models with growth-yield models and ecophysiological models. As computer technology advances explosively, individual-based models could be much more efficient and user-friendly. There have existed disproportionately few individual-based models for biodiverse forests such as evergreen tropical rain forests. Development of individual-based models for tropical rain forests is more challenging and is being stimulated by new international conservation efforts.