Most landowners and livestock producers in the Great Plains all share a common struggle, woody plant encroachment. Most of the remaining native rangelands have experienced woody plant encroachment to some degree. Historically the woody plants in the Great Plains had been kept in check by a combination of frequent fire and grazing/browsing by multiple species of herbivore.
Historically, North American grasslands were grazed/browsed by a suite of large herbivores (i.e., bison, elk, pronghorn, and deer. Currently, we have replaced the native grazer, bison, with domesticated cattle but we have failed to replace the browsers (O’Connor et al., 2020). Much of the winter diet of elk on tallgrass prairie is comprised of woody plants (Conrad and Gipson 2012). Data from pronghorn in the Flint Hills ecoregion in Kansas suggest that woody plants, mainly Rhus spp., make up much of their summer and early fall diet (Ganey 1998). The ability for elk to control a woody species becomes apparent when looking at the indirect effect of the wolf reintroduction had on willow trees in Yellowstone (Creel and Christianson 2009).
Cattle have large broad mouths and typically take large bites of entire plants. In most cases, cattle diets are composed of about 70% grasses, 15% forbs and 15% woody plants while goats’ diets are typically 30% grasses, 10% forbs and 60% woody plants (Van Dyne 1980). The diet composition of sheep is typically around 50% grasses, 30% forbs and 20% woody plants. The small mouth and prehensile lips of sheep and goats allow them to select certain parts of plants. Not only do the diets of these livestock species differ but the areas in which they will forage are different as well. Sheep and goats tend to utilize steeper, less accessible areas than cattle do.
Over a long-term study (23 years) at the Texas A&M Sonora Research Station goats alone reduced the canopy cover of woody plants by 83% (Merrill and Taylor, 1976). As the sole brush management technique, goats have been successfully used as a brush management technique but pairing goats with other brush management treatments such as fire tends to improve the efficacy of the brush management (Brock 1988). A prescribed fire can shorten the stature and change the structure of many resprouting woody plants, allowing goats to utilize these plants. Persistent browsing of woody plants by goats, be it the leaves, small branches or bark leads to the reduction or removal of that plant. As an added benefit, goats eat some of the non-native, invasive species such as sericea lespedeza (Lespedeza cuneata).
The Prairie Project aims to identify longer-term solutions to woody plant and encroachment using prescribed fire and goats. Prescribed fire is a very economic pre-treatment for goat browse. Prescribed burning can top kill larger trees that goats would not be able to defoliate, making them re-sprout from the base and providing high quality forage at ground level. Implementing goats after a brush treatment of any kind is a good way to maintain the open areas you have created as re-sprouts will be preferentially browsed by the goats.