9419922 Davis This project is a study of habitat change in a sand plain oak savanna in east central Minnesota. A threatened habitat in Minnesota, oak savannas are converted to oak woodlands in the absence of fire. In this process, patches of oak trees expand, connect, and encircle patches of prairies. Conversely, when fire is reintroduced, oak woodlands are opened up as patches of trees shrink, subdivide, and even disappear. Thus, the study of habitat change in these oak dominated environments is partly a study of pattern formation. One of the objectives of this study is to identify factors that influence the pattern development of oaks in the habitat. Factors to be investigated include landform effects, effects of pocket gophers, fire, and effects of existing herbaceous and woody vegetation. A second objective is to quantify some of the important physical and biological consequences of the changes in the oak vegetation, including effects on shrubby and herbaceous vegetation, pocket gopher and thatch ant distribution, litter layer, oak recruitment, and fire intensity. The project's methodology includes analysis of aerial photographs and spatially referenced data collection from a ground grid using geostatistics and GIS; an experimental garden study to investigate the effects of shade, water, and surrounding landscape on seedling survivorship and growth; and an experimental plot study to measure the effects of fire and the physical removal of shrubs and oak saplings on the herbaceous community. The methodology has been developed to permit the study of pattern formation at several spatial and temporal scales. %%% By elucidating mot only the patterns but the processes and mechanisms that produce the patterns, this study will contribute to our understanding of site history and habitat change in oak savanna and woodland environments. Information gathered from this study will specifically complement studies on oak regeneration as part of the Cedar Creek Long-term Ecological Research Project. Fin ally, the proposed project will provide data that can lead to improved management plans for one of the upper midwest's most threatened habitats.
