Size bimodality in plant populations: an alternative hypothesis
Symmetric competition among seedlings in a spatially random population was simulated using the exponential growth function. In these simulations each plant was randomly assigned values for m/sub 0/ (initial seed mass), r (exponential growth rate), and germination time chosen from normal distributions. The growth rate reduction factor resulting from neighbors within each plant's zone of resource depletion was calculated as the inverse of the number of plants within the zone. This reduction factor was multiplied by the randomly assigned exponential growth rate to determine the actual exponential growth rate for each plant. Bimodality produced by this model is a consequence of the discontinuous distribution of exponential growth rates resulting from a Poisson distribution of the number of neighbors. This simple model based on symmetric competition in a spatially random population provides an alternative mechanism for the appearance of bimodality. The model may explain why increasing plant density in experiments with regularly spaced plants produces results that conflict with patterns found in experiments with a random spatial pattern. 10 references, 2 figures.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5693602
- Journal Information:
- Ecology; (United States), Vol. 67:1
- Country of Publication:
- United States
- Language:
- English
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