Estimating Shrub Production from Plant Dimensions

Abstract

Relationships between current season plant production and plant measurements (crown width and volume) were investigated for 4 South Texas shrubs collected during July, 1978. Shrubs investigated were blackbrush (Acacia rigidula), guajillo (A. berlandieri), shrubby blue sage (Salvia ballotaeflora), and kidneywood (Eysenhardtia texana). Regressions of production available to white-tailed deer on both crown width and crown volume yielded coefficients of determination of 25-97%. Log-log and quadratic equations provided better results than linear, logarithmic, or exponential equations. One plant measurement (maximum crown width as an independent variable) produced results comparable to those from crown volume. Range site (sandy loam or gray sandy loam) did not affect plant production:plant measurements relationships, but mechanical treatment (shredding) did. Selecting plants representing the full range of shrub shapes and sizes is critical to the proper use of this method, and treatments which greatly modify plant form will probably require regression equations separate from those for undisturbed vegetation.