A Neighborhood Model of Annual‐Plant Interference

A model is constructed in which seed production by individual annual plants within a population is a function of the number and species of individuals within each of several concentric neighborhoods. The effect of increasing competition is to reduce seed production in a hyperbolic fashion, and the contribution of each individual to this effect is inverse proportion to the square of its distance from the test individual. A simple monospecific version of this model was tested on populations of two annual knotweeds. A least—squares fit of the model accounted for over 80% of the variation in seed production. This model provides an alternative to density in describing plant populations. A monospecific aggregated version can be seen as an extension of the inverse—yield law, which has been widely applied to monocultures.