Interrelationships of Huisache Canopy Cover with Range Forage on the Costal Prairie

Abstract

Grass production was monitored based on seasonal harvests under various canopy covers of huisache on a Coastal Prairie blackland range site during 1978 and 1979. Grass production (Y) was not decreased in 1978, compared to that on essentially brush-free areas, until huisache canopy cover (X) exceeded 30% based on the relationship, the average of Y = 2,346 + 20X - $0.62X^2. Texas wintergrass standing crop apparently increased as huisache canopy cover increased to 25%, and its growth during winter partly compensated for standing crop losses of warm season species during the winter. In 1979, the contribution of the cool-season species was masked by greater production of warm-season species. Consequently, grass production decreased with increasing huisache canopy cover according to the relationship, the average of Y = 4,047 - 14.9X - $0.29X^2. Based on the functional relationship the average of Y = a – b1X-b2X^2, coefficients of determinations (r2) ranged from 0.50 to 0.96 when estimates of annual production of grasses or production for the growing season only were regressed against huisache canopy cover.