Effects of Fire Frequency on Plant Species in Oak Savanna in East-Central Minnesota

TESTER, J. R. (Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108). Effects of fire frequency on plant species in oak savanna in east-central Minnesota. Bull. Torrey Bot. Club 123: 304-308. 1996.-From 1964 through 1984, nine forest sites, ranging in size from 2.6 to 27.5 ha, were each burned from two to 19 times. Percent cover of 13 of 14 true-prairie grasses was positively correlated with burn frequency. Of these, eight have C4 and six have C3 photosynthetic pathways. Cover of 34 of 39 true-prairie forbs, and of Amorpha canescens, increased with frequency of burning. All except Aster oolentangiensis are C3 species. Cover of six of seven native, not prairie, species, all C3, decreased with increasing burn frequency. These data suggest that the adaptation of true-prairie species to repeated burning outweighs the effects of their photosynthetic pathways.