Location: Range and Livestock Research2011 Annual Report
1a. Objectives (from AD-416)
Objective 1: Develop strategies and decision tools to proactively manage livestock grazing, fire, and drought impacts on Great Plains community structure and function. Sub-objective 1.A. Determine plant community and livestock response to post-fire grazing deferment. Sub-objective 1.B. Determine plant community response to fire return interval and seasonality. Sub-objective 1.C. Determine patch burning effects on plant community dynamics, animal performance, grazing distribution, and foraging efficiency. Sub-objective 1.D. Characterize grazing history effects on rangeland integrity and stability. Objective 2: Improve animal productivity and product quality based on predicted nutrient intake, forage dynamics, and diet selection processes in the northern Great Plains. Sub-objective 2.A. Determine effects of forage quality on autumn forage intake as it interacts with cow lactation and gestation status. Sub-objective 2.B. Determine rumen microbial response to noxious weed consumption by sheep and cattle. Objective 3: Develop management strategies to restore rangelands degraded by weeds and prevent weed invasions in the northern Great Plains. Sub-objective 3.A. Determine interacting effects of fire and grazing on annual brome dynamics. Sub-objective 3.B. Provide weed management protocols adjusting for inter-annual variation. Sub-objective 3.C. Develop an internet-available system to quantify site-specific invasive weed impacts. Sub-objective 3.D. Develop grazing strategies to reduce invasive weed population growth rates.
1b. Approach (from AD-416)
The planned research is designed to improve sustainability of rangeland production by addressing the interacting effects of disturbances on stability and integrity of rangelands and efficiency of livestock nutrient conversion. Objectives are to: 1) Develop strategies and decision tools to proactively manage livestock grazing, fire, and drought impacts on Great Plains community structure and function; 2) Improve animal productivity and product quality based on predicted nutrient intake, forage dynamics, and diet selection processes in the northern Great Plains; and 3) Develop management strategies to restore rangelands degraded by weeds and prevent weed invasions in the northern Great Plains. Experiments are integrated across objectives and will determine the interacting effects of grazing, fire, drought, and invasive plants on plant communities (production, species composition, diversity, heterogeneity, propagation, and survival) and the effects of changes in vegetation and animal physiology on livestock (weight gain, distribution, diet quality, diet selection, diet diversity, foraging efficiency, forage intake, and rumen microbial diversity). Two experiments are replicated across three locations (Miles City, MT, Nunn, CO and Woodward, OK) to determine ecological ramifications of fire seasonality, return interval, and grazing interactions in semiarid rangelands on a north-south gradient across the western Great Plains. Understanding the mechanisms that control disturbance effects on rangelands and animal responses to alterations in the plant community will promote development of proactive management strategies for improved stability in rangelands and rangeland livestock production systems.
3. Progress Report
This report documents research conducted under the in-house project 5434-21630-002-00D, Proactive Management for Sustainable Rangeland Production. Milestones were primarily limited to treatment application and data collection during this reporting period. This project addresses goals outlined in the NP 215 Rangeland, Pasture and Forages Action Plan under Component I (Rangeland Management Systems to Enhance the Environment and Economic Viability) and supports ARS strategic plan Objective 5.1 (Provide Science-Based Knowledge and Education To Improve the Management of Forest, Rangelands, and Pastures). For Objective A.2, post-fire deferment effects on sheep diet quality and weight gain were published and cattle deferment experiments are being planned. Plant community response data following summer fire have been published as well as data on fuel load and heat dosage effects on pricklypear cactus. A database has been created for combining and handling data for fire effects on livestock distribution. Data are analyzed for fire and grazing interactions on annual brome population dynamics and laboratory experiments on growth regulating herbicide effects on cheatgrass seed production were extended, in support of Objective C.1. Portions of this project are related to or coordinated with research in NP 304 Crop Protection and Quarantine (weed biology and ecology; plant, pest and natural enemy interactions and ecology).
1. Summer fire effects in northern grasslands. Summer is the period of most wildfires in the western United States, but documentation of plant community and soil environment responses to fire is limited for semiarid grasslands. ARS researchers in Miles City, MT, evaluated summer fire effects on soil temperature, soil moisture, plant productivity, and community composition over four years in the Northern Great Plains. They determined that productivity was similar between burned and non-burned sites and more responsive to precipitation than fire. Summer shifted the plant community toward greater dominance by native perennial grasses and reduced exotic annual grasses and forbs. The fire-induced changes in species composition suggest exclusion of fire may be a greater disturbance to this ecosystem than summer fire. Data supporting development of policies and management actions concerning summer wildfire enhances sustainability of rangeland and should ensure maximum economic return to ranchers in the Northern Great Plains.
2. Livestock often concentrate grazing in particular regions of landscapes while partly or wholly avoiding other regions. Dispersing livestock from the heavily grazed regions is a central challenge in grazing land management. ARS researchers in Miles City, MT, in cooperation with the US Forest Service evaluated factors driving livestock aggregation patterns in partially forested range in eastern Oregon. The point where cattle initially entered a pasture was the primary driver of subsequent grazing distributions. Results indicate that by instituting simple, inexpensive changes in where livestock enter pastures, managers could prevent overgrazing and increase sustainability and profitability. Altering pasture entry into large pastures and allotments can be considerably less expensive and more easily implemented than traditional livestock distribution tools, including herding, water development, fencing, and movement of supplement locations.
Reinhart, K.O., Van Der Putten, W.H., Tytgat, T., Clay, K. 2011. Variation in specificity of soil-borne pathogens from a plant’s native range versus its non-native range. International Journal of Ecology. online doi:10.1155/2011/737298