The size frequency distributions, plant density, age and community disturbance

摘要

We show that explicit mathematical and biological relationships exist among the scaling exponents and the allometric constants (αandβ, respectively) of log-log linear tree-community size frequency distributions, plant density N_T, and minimum, maximum and average term diameters (D_(min) D_(max), and D, respectively). As individuals grown in size and D_(max) increases, N_T is predicted to decrease as reflected by a decrease in the numerical value of αand an increase in the value of β. Our derivations further show that N_T decreases as D~- increases even if D_(min) or D_(max) remain unchanged, Because D_(max) and the age of the largest individuals in a community are correlated, albeit weakly, we argue that the interdependent relationships among the numerical values of α,β, N_T, and D~- shed light on the extent to which communities have experienced recent global disturbance. These predicted relationships receive strong statistical support using two large datasets spanning a broad spectrum of tree-dominated communities.