Submitted to: Jornada Trails
Publication Type: Popular Publication
Publication Acceptance Date: 3/15/2006
Publication Date: 4/10/2006
Citation: Estell, R. 2006. Plant-Animal Interactions. Jornada Trails. 10(1):3.
Technical Abstract: Shrub invasion into desert grasslands is an ongoing concern for ecologists and land managers. These shrubs typically contain chemicals that make them unpalatable for livestock and wildlife. Tarbush is a shrub that has invaded productive soils in the northern Chihuahuan Desert. For several years, we have been using tarbush as a model invasive shrub to explore the chemicals involved in plant-animal interactions. From a chemical standpoint, not all tarbush are alike. Sheep and goats select some tarbush plants and avoid others based on the concentration of volatile chemicals on the leaves. When we removed these chemicals using organic solvents, lambs ate more tarbush. Furthermore, when we removed these chemicals from tarbush and added them to a palatable food, animals ate less. We are now examining effects of individual compounds to determine if specific chemicals are critical drivers of diet selection. To date, we have tested effects of 23 volatile chemicals (primarily terpenoids) on intake by lambs, and two more compounds are currently being examined. Only four chemicals (camphor, alpha-pinene, camphene, and caryophyllene oxide) reduced the amount of food eaten. By learning which specific compounds drive diet selection, we hope to ultimately be able to manipulate browsing behavior of livestock and other herbivores.