Abies population dynamics simulated using a functional-structural tree model

Abstract

A functional-structural model, PipeTree, based on Abies population data has been developed to reveal the interactions among processes at physiological, individual and population scales. Using field measurements obtained in a comprehensive series of research studies on subalpine Abies forest stands on Mt. Shimagare during the 1950s to 1980s, we designed the structural components and physiological process models for PipeTree. The results of the PipeTree simulation support the feasibility of using a functional-structural tree model to evaluate ecosystem performance at the stand level. PipeTree generates patterns similar to those in real subalpine forests, such as diameter-height relationships and time changes in basal area. After demonstrating the validity of the dynamics of a PipeTree population, we applied a sensitivity analysis under a productivity-enhanced environment in which the maximum photosynthetic rate (Pmax) of PipeTree foliage was increased by 50% (caused, for example, by CO2 enrichment). The results of Pmax enhancement simulation show that the 50% increase in Pmax doubles the net primary production (NPP) in the PipeTree stand. These results suggest the importance of canopy structure in evaluating the function of terrestrial ecosystems. © The Ecological Society of Japan 2005.