Analysis of Canopy-Gap Structures of Forests by Ising-Gibbs States - Equilibrium and Scaling Property of Real Forests -

Abstract

Canopy is the uppermost branchy layer of trees and spatial distribution of canopy gaps is important for the coexistence of species and the forest dynamics. A new method to analyze the canopy-gap structure is proposed, in which configurations of canopy-gap sites are approximated by the Ising-Gibbs states with two parameters. Results of the application to the real data of a neotropical forest in Barro Colorado Island, Panama, and of a deciduous forest in Ogawa Forest Reserve, Japan, show the validity of our method. Canopy-gap structures of the forests are not exactly critical but nearly critical and the scaling argument of the Ising spin configurations is useful to explain the power-law distributions of gap sizes reported by ecologists.