Creosote Bush, an Arid Zone Survivor in Southwestern U.S.: 1. Identification of Morphological and Environmental Factors that Affect Its Growth and Development

Abstract

Creosote bush (Larrea tridentata [DC.] Cov.) is a perennial shrub which is a major dominant species in arid rangelands in southwestern Texas, U.S. Controlling creosote bush in desert rangelands is important because as it increases in density, perennial grass production is reduced. The purpose of this study was to investigate the association between morphological characteristics and understand how these characteristics interact with the environment to affect production of creosote bush. In this study, a range of morphological traits was investigated at several southwestern Texas sites, and growth ring and growth rate were o measured. Creosote bush plants with a wide range of ages occurred mostly in pure stands and sometimes in small groups in all study sites. Two groups were categorized based on the crown size: CB1 (mostly conical-shaped shrubs) and CB2 (mostly large hemispherical-shaped shrubs). The proportion of CB1 and CB2 at a site affected creosote bush production. Creosote bush productivity was highly associated with soil water availability. In wetter sites, more CB2 shrubs occurred than CB1, resulting in higher production. The results of this study can improve understanding of the most important factors that affect creosote bush production, which is critical for developing management strategies for desert rangelands.