Influence of Canopy Removal by Burning or Clipping on Emergence of Eragrostis lehmanniana Seedlings

Abstract

Abstract Eragrostis lehmmniana (Lehrnann lovegrass) is a warm-season bunchgrass native to South Africa which dominates many desert grassland sites in southern Arizona. To determine why fire results in high seedling recruitment of this species, we measured germination of seeds in the seedbank and field seedling emergence following 1) no treatment, 2) burning, 3) clipping and herbicide and 4) herbicide d y . Treatments were designed to compare the effects of initial fire heat treatment with those of canopy removal, as affecting seedbed temperatwe, light and water availability, on seedling emergence. Treatments were replicated over 2 years on a stand of Lehrnann lovegrass at the Santa Rita Experimental Range. Canopy removal, by either clipping or burning, increased seedling emergence in seedbank samples taken prior to summer rains and greatly increased field seeding emergence. High seedling emer- gence after canopy removal was not the result of greater seedbed water availability but probably the result of a greater range in diurnal soil temperatures and increases in red light reaching the seedbed, both of which stimulate germination. The ability of E. lehmanniana to persist after fire indicates that prescribed burning could be used to control associated woody plants and improve forage palat- ability of E. lehmanniana dominated grasslands.