Buffalo used to be the largest ruminant on the North American continent. Now, the ecological role of buffalo has been taken up by domesticated cattle. The BLM plays a huge role in managing ranching operations on public lands, and strives to make sure that sustainable yields of cattle can be maintained long into the future.
As part of the management of ranching operations, the BLM performs rangeland health assessments, which are reports outlining the ecological health of land grazed by cattle. To provide an inter-disciplinary examination of the land, we pool our expertise with the range team and the wildlife team. Ranchers in these arid plains need to be careful to not overgraze their allotments. Grasses take a long time to become established, and if a herd of cows grazes all of the grass to the ground, it may be five or ten years before anything can grow on the sandy soils. Furthermore, overgrazed areas are prone to invasion by non-native species, which are not as palatable to cows, and very difficult to remove. The wildlife team is mostly concerned with making sure that enough habitat remains in these areas to support the sage-grouse, a threatened species.
The hydrologists are concerned with the health of wetland areas. In the summer, a cow may return to a water source three or four times a day in order to drink. Many times these water sources are artificial troughs fed from wells, but sometimes they may travel to natural sources of water. Hydrologists are responsible for monitoring the health of the riparian areas on public lands, which in this case, often means making sure that the wetland areas are not over-used. We are looking for signs of damage to the fragile ecosystems, like deep hoof-prints, which form bumps over time (called hummocks).
The hydrologists are also responsible for taking and processing soil samples. We are updating the Natural Resource Conservation Association’s soil type map. Soil type, along with precipitation, is the most important predictor of ecotype. Soils with a good balance of silt, clay, and sand, tend to be better able to support grasses. Many ranches lease land on sandy soils which are more prone to erosion, and have a lower yield than more loamy soils. Updating the soil information helps the range team create accurate estimates of how many head of cattle one acre of land can support.
Ranching is definitely not an easy task in the arid plains of central Wyoming, and participating in the rangeland health assessments has helped me to appreciate the vast quantities of land needed to support cattle. Sometimes I try to visualize the large herds of bison that used to run through the plains of the United States. And sometimes, if I try hard enough, I can hear the thunder of their hooves rushing along to green pastures.