The effects of soil disturbances on tallgrass prairie

A major goal of ecological research is to identify patterns of plant community structure and the mechanisms responsible for generating them. Understanding plant community structure and dynamics requires a knowledge of the interactions of disturbances and the manner in which they influence ecological variables across hierarchical levels of time and space.; Naturally and artificially created patterns of soil disturbance were used to assess the effects of pocket gopher activities on tallgrass prairie. Pocket gopher mounds and burrows significantly decreased species richness, diversity, and productivity at the local scale of the disturbances. These patterns were transient however, and no effect of the disturbances was observed at larger spatial scales. Simulated burrow and mound disturbances had modest effects on plant community structure only at the highest disturbance intensities. Several of these patterns were observed at larger scales and after longer time periods. Further, many of these patterns were differentially affected by the interaction of the soil disturbance and fire.; Studies of recolonization on soil disturbances revealed that the seed rain, soil seed bank, vegetative reproduction, and regrowth of buried vegetation are all important mechanisms of tallgrass prairie plant species regeneration on disturbed sites. The size of a soil disturbance also influenced abiotic resources and the relative contribution of each plant regeneration strategy.; Tallgrass prairie plant communities showed considerable resilience to soil disturbances. The coevolutionary history of tallgrass prairie vegetation with a variety of perturbation agents has led to adaptations which allow the competitive dominants, primarily C4 tallgrasses, to rapidly recover from disturbance events. This limits community coexistence with less competitive species and reduces the overall impact of individual pocket gopher disturbances on plant community structure.; This research has contributed to our understanding the effects of soil disturbances on grassland population dynamics and community structure. It has increased our knowledge of the mechanisms by which disturbances are translated into patterns in resources and vegetation and has furthered our appreciation for the manner in which disturbance interactions influence ecological variables across multiple spatial and temporal scales.