Animal and shrub interactions: Developing a tarbush model

Title	Animal and shrub interactions: Developing a tarbush model
Publication Type	Conference Paper
Year of Publication	1993
Authors	Fredrickson E.L., Estell RE, Havstad K
Conference Name	8th Wildland Shrub and Arid Land Restoration Symposium
Date Published	1993
Conference Location	Las Vegas, NV
Abstract	Large areas of the Chihuahuan Desert are undergoing a transition from semiarid grassland to desert scrub. The role of mammalian herbivores in mediating this transition has been suggested but has not been adequately described. A better understanding of plant-animal interactions may assist in developing animal-based technologies to increase shrub use while mediating vegetational change. Tarbush (Flourensia cernua), an aromatic shrub rapidly invading productive range sites, was used as a model to examine the influence of leaf surface compounds on the use of tarbush by domestic sheep. Additional studies also were designed to examine the digestive and physiological consequences of ingestion of tarbush leaves. Results from these studies indicate: (1) dietary preference is influenced by either epicuticular waxes or a component of the wax, (2) intraspecific variation of epicuticular chemistry varies both temporally and spatially, (3) nutrient concentrations are similar to alfalfa, (4) ruminal fermentation patterns are altered by inclusion of tarbush in grass diets, and (5) toxicosis can result from chronic consumption of tarbush leaves. Interpretation of these data suggest controlled use of tarbush by sheep is possible, but use of sheep to mediate desired vegetational change may be limited.