A simulataion model of primary production and carbon allocation in the creosote bush Larrea-tridentata

Cunningham, G.; Reynolds, J.

A preliminary simulation model of primary productivity and C allocation in creosotebush (L. tridentata [DC] Cov.) is described. The model utilizes a system approach in which movement of assimilate within the plant is in response to changes in source-sink strengths of leaves, stems, roots, early reproductive buds, maturing reproductive buds, flowers and fruits. Two distinct compartments are defined per organ or developmental stage to separate assimilate into a pool fraction (labile or translocatable) and a structural fraction (nonlabile). The changes in magnitude (within upper and lower limits) of a pool compartment during the course of a simulation (i.e., growth and development of the plant) are function of the rates of maintenance respiration and growth as well as a priority scheme governing allocation of assimilates; the increases and decreases in dry weight of a structural compartment are a function of aging and the magnitude of this associated pool (which determines structural growth and physiological death). A l1 yr simulation of a hypotehtical Larrea plant shows that the model exhibits a reasonable behavior, although no validation is attempted at this stage in its development. The heuristic value of the model is illustrated in the sensitivity analysis, which shows the need for detailed knowledge of priority C movement during both vegetative and reproductive periods, the importance of substrate controlled respiration rates and the need for further studies of the dynamics of labile pools in the plant. The model was an excellent tool in the initial attempt to integrate the voluminous information on Larrea into a complete. function description of autecology of the species. Further refinement of this model as data from the current research and that of other investigators become available should lead to a better understanding of the ecological role of Larrea in desert ecosystems.

A simulataion model of primary production and carbon allocation in the creosote bush Larrea-tridentata

Series