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Citation. Tester, J. R. 1989. Effects of fire frequency on oak savanna in east-central Minnesota. Bulletin of the Torrey Botanical Club 116(2):134-144. [1154 E133 LTER]
Abstract. From 1964 to 1984, prescribed burning experiments were performed on oak (Quercus spp.) forest and oak savanna in east-central Minnesota USA. Eighty-nine burns were carried out on 9 compartments ranging from 2.6 to 27.5 ha. Intervals between fires varied from I to 12 years. Soil pH increased significantly with frequency of burning. Total nitrogen was positively correlated (P < 0.01) with per cent organic matter. Species richness was highest in areas which were burned approximately every 2 years. Different plant functional groups responded differently to frequency of burning. Cover of true prairie grasses increased from less than 5 to about 15 per cent. True prairie forbs showed a significant increase in cover from less than 2 to about 8 per cent with increasing frequency of burning. Density of true prairie shrubs showed a tendency to increase whereas density of non-prairie shrubs and of trees showed tendencies to decrease with increased frequency of fire. Thus. the frequency of prescribed burning strongly influenced vegetative composition and physiognomy as well as soil characteristics.
Keywords. oak savanna, prescribed burning, succession, prairie plants, nitrogen, species richness