Effects of Agricultural Terraces on the Reestablishment of Bluestem Grasslands

Abstract

The effects of agricultural terraces on the reestablishment of a bluestem grassland were evaluated 5 years after seeding. Terrace intervals (the slopes extending between terraces), terrace channels, terrace ridges, and terrace slopes (2 meters downslope from the terrace ridge) in both burned and unburned areas were evaluated. Canopy cover for all seeded native grasses averaged higher on terrace locations than on terrace intervals. Little bluestem (Andropogon scoparius) and Indiangrass (Sorghastrum nutans) were best established in terrace-channels, whereas sideoats grama (Bouteloua curtipendula) and blue grama (B. gracilis) were most abundant on terrace-ridges. Big bluestem (Andopogon gerardii) coverage was greatest on terrace-channels in burned and terrace-slopes in unburned areas. Canopy cover of nonseeded grasses and forbs averaged highest on terrace-ridges and terrace-slopes; forbs were markedly reduced as a consequence of burning but foxtail (Setaria spp.) increased. Total productivity was substantially greater on terrace locations (6,757 kg/ha) than on terrace intervals (3,620 kg/ha). Burning reduced total biomass the year of the burn with the reduction most pronounced in the terrace-channel where productivity was highest. This study indicates that terraces provide microhabitats which result in species distributions that differ markedly from those expected for native prairies. In addition, terrace conditions appear to slow the process of establishing a continuous stand of native perennial grasses. Thus, it appears to be advisable to remove terraces and redistribute terrace soil prior to reseeding with native grasses.