A Ten-Year Record of Aboveground Biomass in a Kansas Tallgrass Prairie: Effects of Fire and Topographic Position

Abstract

Measurements of mid-season live and dead aboveground biomass are reported for a 10-yr period (1975-84) in a northeast Kansas tallgrass prairie. Study sites included shallow, rocky upland and deep, non-rocky lowland soils in annually bumed (April) and unbumed watersheds. Lowland sites had significantly greater live biomass than upland sites for both bumed and unbumed prairie for the 10-yr period. Moreover, live biomass was greater on burned than unburned lowland sites, but was not significantly increased by fire on the upland sites. Averaged across upland and lowland sites, mid-season live biomass was 422 g m-2 on annually burned and 364 g m-2 on unburned sites for the 10-yr period. Each site had its lowest live biomass value during the severe drought year of 1980 (range = 185-299 g m-2). During the study period, live biomass was most strongly correlated with seasonal pan water evaporation (r = -0.45 to -0.82), whereas dead biomass was correlated with the previous yr's precipitation (r = 0.61 and 0.90 for upland and lowland sites, respectively). When aboveground biomass was sampled throughout the 1984 season and separated into several components, biomass of the graminoids was 40% lower, whereas that of forbs and woody plants was 200-300% greater in the unburned