Lehmann lovegrass in southeastern Arizona: Biomass production and disappearance

Abstract

Lehmann lovegrass (Eragrostis lehmanniana Nees), a perennial bunchgrass from southern Africa, has recently replaced native grasses on 200,000 ha in southeastern Arizona. Hence the need to determine annual fluctuations in live and dead biomass in wet and dry years. This information is necessary if we wish to determine (1) potential plant productivity changes on Arizona rangelands after the Lehmann lovegrass invasion, and (2) how the presence of Lehmann lovegrass has affected animal utilization and grazing management. Live biomass was present throughout the year but August peaks were almost 2,000 kg/ha in 1 wet summer, 1,430 kg/ha in 2 normal summers, and 960 kg/ha in 1 dry summer. Recent-dead approached zero in August when live peaked, and slowly accumulated in fall and winter. Old-dead peaked before the summer rains when temperature peaked and rapidly disappeared following snow accumulations in winter. Litter was highly variable among sampling areas, plots, and sampling dates but amounts usually peaked before the summer rains and decreased in winter and spring. Lehmann lovegrass annually produces 3 to 4 times more green forage than native grasses, but cattle prefer native grasses more than Lehmann lovegrass.