ATMOSPHERIC CO2, CLIMATE CHANGE, AND TREE GROWTH - A PROCESS MODEL .1. MODEL STRUCTURE

Primary production of forest systems will be significantly changed as atmospheric CO2 concentrations increase and climatic changes occur. This paper presents the structure of a process model to be used for predicting changes in tree seedling biomass accumulation associated with increases in CO2 level and shifts in the abiotic environment. The model is a compartment representation of carbon flow that utilizes the processes of gross photosynthesis, stomatal conductance, growth and maintenance respiration, photosynthate allocation, and photosynthate conversion to biomass. The model is driven by abiotic submodels that provide high-resolution inputs obtained from standard meteorological stations. Independent data sets are used to evaluate the net photosynthesis portion of the model with respect to abiotic inputs; simulated and observed biomass accumulation are compared.