RESPONSE OF A WETLAND VASCULAR PLANT COMMUNITY TO DISTURBANCE - A SIMULATION STUDY

We developed a spatial computer simulation model of the vascular plant community of a freshwater wetland in south-central Wisconsin. This model, based on the aggregation of an unwieldy collection of species into a manageable number of functional ''species-types'', is used to investigate the responses of wetland plant communities to anthropogenic disturbance that resulted in alterations in wetland hydrology. The results of the model are in general (rank-order) agreement with 7 yr of observed changes in vegetation structure of a sedge meadow and shallow marsh adjacent to a 1000-MW coal-fired power plant near Portage, Wisconsin. Sensitivity analysis of the model revealed that functional species' responses to disturbance depended most heavily on seed germination and dispersal characteristics, a result predicted qualitatively by the wetland succession model of van der Valk (1981). Although analyses of the model presented here appear to verify the model, validation of the model will depend on the collection of similar long-term data sets at disparate sites. This model may be of use in predicting the consequences of anthropogenic disturbance on other freshwater wetlands.