Composition and Net Primary Production of Native Prairies in Eastern Arkansas

Abstract

The Grand Prairie region of eastern Arkansas is representative of a series of native prairies that developed on terrace deposits in the lower Mississippi River Valley. Today almost all of the few uncultivated remnants are dominated by broom sedge (Andropogon virginicus) and splitbeard (A. terncarius). The composition and net aboveground primary production were determined for three prairie remnants of the Grand Prairie. Of these, two had been burned and hayed annually for at least 65 years, and the third had been protected for the last 16 years. Approximately 120 species were recorded on each prairie. On the burned and hayed prairies, broom sedge and splitbeard contributed approximately 50% of the annual aboveground yield. Broom sedge and splitbeard were believed to have become dominant in response to long-term burning and haying management. The protected prairie contained neither broom sedge nor splitbeard, and the major part of the annual net production was contributed by composites and legumes. Net primary aboveground production, estimated by summing the peak production of each species, was 623 and 628 g * m72 * yr-1 on the managed prairies and 1131 g * rn-2 * yron the protected prairie. Burning did not enhance production. The differences in aboveground production and the absence of a burn response were also attributed to long-term burning and haying. The seasonal pattern of herbage production revealed a primary peak in late June followed by a second peak in the early autumn corresponding to the maturation of the principal dominants. Preliminary soil data indicated reduced soil fertility for all three prairies, but slightly higher fertility on the protected prairie.