1a. Objectives (from AD-416)
1) Evaluate the effects of fire, mechanical treatments, livestock grazing, introduced invasive weeds, western juniper expansion, and climate on the vegetation and watershed function of sagebrush steppe rangelands. 2) Improve our understanding of livestock behavior and livestock/environment interactions. Improve tools to manipulate livestock behavior and grazing patterns. 3) Understand mechanisms of weed invasion and develop management strategies that can be used to restore rangelands that have been degraded by weeds or other disturbances.
1b. Approach (from AD-416)
The mission of the Burns unit is to provide the science for sound land and livestock management. This five-year plan builds on a rich history of research at this location, in some cases reaching back to the 1940's. Rangelands of the Great Basin are spatially variable and land ownership patterns are a complex mix of public and private land. Annual weather variation is high, and can obscure vegetation responses to management treatments. Ranching forms the basis of the regional economy, underscoring the importance of forage production, and the large percentage of public land in the region translates into public scrutiny of management actions, and a focus on environmental impacts and biodiversity. Invasive species and expanding juniper populations represent major threats to existing land uses and values. Our research program has evolved with substantial public input and addresses questions raised by our customers. Land managers in this region are faced with information gaps in basic sagebrush steppe ecology, vegetation responses to management actions, plant community restoration, seedling establishment and livestock grazing management. Our research program will fill some of those gaps while expanding and enhancing current ecological theory and building on our long-term data sets. The unit also has a commitment to synthesizing research information and developing management tools. Formerly 5360-11630-005-00D (1/08).
3. Progress Report
Under Objective 1 we continued data collection for the juniper hydrology project (1.A); treatments were applied and data was collected on the fire/grazing study (1.B); long-term weather data was screened and analyzed, and vegetation data was collected for exclosures and grazed area (1.C). Cattle with GPS units were deployed at the Northern Great Basin Experimental Range and in large grazing allotments in southern Harney County as outlined in Objective 2. Data processing is currently under way. A third and final year of data collection occurred for Objective 3.A; application of treatments and data collection occurred for 3.B; data collection continued for 3.C and 3.D
1. Grazing reduces fire impacts. Wildfires have increased in severity in the western U.S. in recent years. ARS scientists from Burns, Oregon recently completed a study in which treatments were applied in 1937 (grazing exclusion) and in 1993 (prescribed fire). Vegetation measurements were taken 12, 13, and 17 years after the fire. Long-term grazing exclusion on sagebrush rangeland can result in damage to native grasses from fire, which in turn allows weedy annual plants to invade. The native grasses are important forages for both livestock and wildlife. These results will be of interest to both public and private land owners charged with managing sagebrush rangeland. This is the first study to show how grazing can be used to help maintain native biodiversity in light of increased fires on western rangeland.
2. Limiting weed spread on rangeland. Invasive annual grasses are a major problem on about 60 million acres of western rangeland. ARS scientists from Burns, Oregon demonstrated that seeding competitive desirable grasses can help limit the spread of weedy annuals. The spread of weedy annual grasses is occurring at an alarming rate in the Great Basin. By seeding a competitive perennial bunchgrass in front of an annual grass invasion, the scientists were able to keep the spread in check. These results should be of interest to anyone facing expansion of annual grasses from the roughly 60 million acres of rangeland they currently occupy. The research provides a tool that weed management organizations and private landowners can use to limit expansion of invasive annual grasses and reduce the degradation and fire frequency on western rangeland.
3. Post-fire grazing management. Livestock producers are often unable to use burned public rangeland for at least two years after a wildfire. ARS scientists from Burns Oregon demonstrated that livestock grazing the year after a fire may not damage good condition sagebrush rangeland. It has been assumed that grazing the first two years after a fire can damage the health of rangeland plants. In a 5-year study ARS scientists showed that moderate grazing either one or two years after a fire was not different from deferring the rangeland for two full years. However, the research was conducted on a good condition rangeland and results could vary depending on rangeland type and its initial condition. Livestock and rangeland managers may be able to initiate grazing earlier than previously assumed after a fire, but need to pay particular attention to the health of the rangeland plant community. This information will be used by 31,000 ranchers who have public land permits in the western US, and the federal agencies responsible for managing over 60 million acres of rangelands.
5. Significant Activities that Support Special Target Populations
May potentially benefit small farms (including ranching families and holders of grazing allotments on public land) by maintaining the quality and quantity of the forage base, and by increasing the profitability of pasture and hay production.