Tuesday, August 7, 2007 - 9:20 AM

COS 28-5: Plant competitive interactions in an overlapping depletion zone

Amit Chakraborty, University of California, Riverside and Bai-Lian Li, University of California, Riverside.

Current mechanistic theories of plant competition for belowground resource are based on the concept of local interactions of individual plant with their environment and interactions between plants are indirect. We proposed a simple mechanistic model of plant-to-plant direct competitive interactions by overlapping their depletion zone for a single, diffusion driven, limiting belowground resource while the rate of resource physical transport between overlapping or non-overlapping depletion zones and regional resource pool is constant. The foraging response to limited availability of resource in the neighborhood of interacting plants by root proliferation in resource rich zones which facilitating resource capture by plants, creates overlapping depletion zones. There exist a hierarchy of competing plants in an overlapping depletion zone; the plant belongs to the lower level of the hierarchy, having higher resource capture efficiency and lower resource uptake, is superior in that zone. At competitive equilibrium, best competitor excludes others and occupies that zone. We found a specific plant trait which is common in equilibrium and non-equilibrium direct competitive interactions; this specified plant trait characterizes competitive ability and it is same as R* value characterization at competitive equilibrium and thereby it would be useful proxy measure for  that do not necessarily require the establishment of equilibrial field monoculture.

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