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
Progress was made on all three objectives and their sub objectives during the past year. All the objectives covered in this report fall under National Program 215, Component 1, Problem A. Under Objective 1.A we continue to collect data on the hydrologic inputs and outflows from four small watersheds (< 100ha) near Jordan Valley, OR in far southeastern Oregon. This research is cooperative with the ARS unit in Boise, ID. The initial research conducted under Objective 1.B has been published and shows that deferment of grazing after prescribed fire had little impact on vegetation composition or productivity. Long-term measurements of both productivity and composition are being continued on the site. We continue to measure both climate and vegetation composition in and outside of our 13 growing enclosures at the experimental range. This past year we also worked on summarizing and analyzing 70 years of climate data from the experimental range. The focus this past year under Objective 2 has been to summarize and analyze the large data sets associated with the livestock behavior GPS research. The data relates to grazing behavior of different classes of cows, and factors influencing grazing distribution in very large pastures (> 25,000 ha). Data collection has been completed for objective 3.A and we are currently analyzing the data. Because of the number of zeroes associated with seedling establishment data, we have enlisted the assistance of the Area statistician to ensure the appropriate analysis techniques are applied. Results associated with objective 3.B show that leaf nitrogen productivity (leaf mass per unit of N) was the key trait contributing to variation in N capture among the invasive species tested. A portion of the data has been published and analysis of additional date was continued this past year. The initial results from objective 3.C have been submitted for publication a data collection continues to quantify vegetation trends. Initial results suggest that native species can be established in existing crested wheatgrass stands but are unlikely to persist more than two years. Objective 3.D is focused on long-term vegetation trends after juniper management and during the past year vegetation measurements were continued to quantify changes in plant community composition.
1. Managing Soil Nitrogen. There is a perception among land managers that reducing soil nitrogen will help desirable perennial grasses compete with annual weeds. ARS scientists from Burns, Oregon, and several other ARS locations conducted research and summarized existing research on this topic. Their conclusions are that reducing soil nitrogen does not allow perennial grasses (such as bluebunch wheatgrass) to compete more effectively with annual weeds (such as Cheatgrass and medusaheads). These results will allow researchers to more effectively target their efforts elsewhere to reduce annual weedy grasses.
2. Post-wildfire reseeding. Invasion by annual grasses after wildfire is a problem in most of the Great Basin, and reseeding after wildfires is intended to reduce the problem. Unfortunately the success of post-wildfire reseeding is variable. Scientists from Burns, Oregon documented a much higher reseeding success (a five-fold increase) on soil formerly under a sagebrush canopy (removed by fire) than in soil between sagebrush plants. These results suggest that there may be soil properties which can be altered to dramatically improve reseeding success on rangeland.
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.