A Simulation Model of Primary Production and Carbon Allocation in the Creosotebush (Larrea Tridentata [DC] COV.)

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Wiley is collaborating with JSTOR to digitize, preserve and extend access to Ecology This content downloaded from 128.233.210.97 on Tue, Abstract. A preliminary simulation model of primary productivity and carbon allocation in creosotebush (Larrea tridentata [DC] Cov.) is described. The model utilizes a systems 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 a 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 its associated pool (which determines structural growth and physiological death).A 1-yr simulation of a hypothetical 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" carbon movement during both vegetative and reproductive growth 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 has been an excellent tool in our initial attempt to integrate the voluminous information on Larrea into a complete functional description of the autecology of the species. Further refinement of this model as data from our current research and that of other investigators become available should lead us to a better understanding of the ecological role of Larrea in desert ecosystems.

THE EFFECTS OF INDIVIDUAL VARIATION IN PHYSIOLOGICAL AND MORPHOLOGICAL TRAITS ON THE REPRODUCTIVE CAPACITY OF THE COMMON COCKLEBUR, XANTHIUM STRUMARIUM L.

“…The available data indicate that the physiological regulation of reproductive success involves many interacting factors rather than a single dominant trait (Gifford and Evans, 1981;Zelitch, 1982). Cunningham and Reynolds (1978;Reynolds and Cunningham, 1981) have modelled the effects ofphysiological functions and patterns of biomass allocation on reproductive success in Larrea tridentata under different levels ofwater availability. Only by allowing allocation patterns to vary with water availability were they able to successfully predict flower and fruit production in this desert shrub.…”

Some Often Overlooked Plant Characteristics as Determinants of Plant Growth: A Reconsideration

“…Numerous, much more sophisticated approaches have been published in the literature, starting from very different levels of process complexity (e.g. Fick, Loomis & Williams, 1975;Cunningham & Reynolds, 1978;Lang & Thorpe, 1983;Schulze, Schilling & Nagarajah, 1983;Coughenour, McNaughton & Wallace, 1984;Zelawski & Szlenk, 1984;Hunt & Lloyd, 1987;Johnson & Thornley, 1987;Hirose, 1988). For the present purpose it is useful to first list all the assumptions necessary to keep such a model as simple as possible (Table 2).…”

Experimental Ecological Genetics in Plantago: A Structural Equation Approach to Fitness Components in P. Aristata and P. Patagonica

“…The structural equation approach may be contrasted to more explicit simulation models of growth and primary production (e.g., Grace andWoolhouse 1974, Cunningham andReynolds 1978). These models have used a systems approach to simulate the movement of assimilate through leaves, stems, roots, and various stages of flower maturity.…”