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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCED MODELS AND CONSERVATION PRACTICES FOR WATERSHED RESOURCE MANAGEMENT AND ASSESSMENT

Location: Grassland, Soil and Water Research Laboratory

Title: Creosote bush, an arid zone survivor in southwestern U.S.: 1. Identification of morphological and environmental factors that affect its growth and development

Author
item Kim, Sumin
item Kiniry, James
item Loomis, Lynn

Submitted to: Journal of Agriculture and Ecology Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2017
Publication Date: 5/15/2017
Publication URL: http://handle.nal.usda.gov/10113/5700688
Citation: Kim, S., Kiniry, J.R., Loomis, L. 2017. Creosote bush, an arid zone survivor in southwestern U.S.: 1. Identification of morphological and environmental factors that affect its growth and development. Journal of Agriculture and Ecology Research International. 11(4):1-14. doi:10.9734/JAERI/2017/33204.

Interpretive Summary: Creosote bush is a desert evergreen, 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 is to investigate the association between several plant characteristics and understand how these characteristics interact with the environment (e.g., slope, elevation, and water runoff index) to affect distribution, abundance, and production of creosote bush. In this study, a range of morphological traits were investigated at several southwestern Texas sites, and growth ring and growth rate were also measured. Creosote bushes with a wide range of ages (3 - 18 years) occurred mostly in pure stands and sometimes in small groups in all study sites. Two groups were categorized based on the crown size: smaller, conical-shaped shrubs and larger, hemispherical-shaped shrubs. The proportion of these two size classes at a site affected creosote bush production. Creosote bush productivity was highly associated with soil water availability. In wetter sites, more larger class shrubs occurred than the smaller class shrubs, resulting in higher production. The total density of creosote bush decreased as land slope increased. This may be due to high water limitation in steeper slopes. The results of this study will improve understanding of the most important factors that affect creosote bush production, which will help to develop management strategies for desert rangelands.

Technical Abstract: Creosote bush (Larrea tridentata [DC] Cov.) is a xerophytic, evergreen, 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 is to investigate the association between a range of morphological characteristics and understand how these characteristics interact with the environment (e.g., slope, elevation, and water runoff index) to affect distribution, abundance, and production of creosote bush. In this study, a range of morphological traits were investigated at several southwestern Texas sites, and growth ring and growth rate were also measured. Creosote bushes with a wide range of ages (3 - 18 years) 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 (Mg/ha). Creosote bush productivity was highly associated with soil water availability. In wetter sites, more CB2 shrubs occurred than CB1, resulting in higher production. The total density of creosote bush was negatively correlated with land slope. This may be due to high water limitation in steeper slopes. The results of this study will improve understanding of the most important factors that affect creosote bush production, which will help to develop management strategies for desert rangelands.

Last Modified: 10/19/2017
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