Location: Range and Livestock Research2012 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:
Season and frequency of fire treatments were applied, vegetation measurements were taken and the study was expanded to include soil microbial DNA and RNA, and grass axillary bud dynamics. Long-term livestock exclusion data were collected as well as final data examining grazing history effects on rangeland resistance to fire and grazing. A preliminary experiment was conducted to evaluate dose and type of methionine supplements on forage digestion and serum concentrations. Data from this study will assist in the supplement selection for proposed studies in the new project. A study to evaluate the role of cobalt addition to the rumen on forage digestion, microbial enzyme activity and subsequent production of vitamin B12 in serum was completed. Greenhouse studies evaluating herbicide (aminopyralid and Picloram) effects on cheatgrass seed viability were concluded and a manuscript has been submitted. Mycorrhizal pure cultures were amplified for future mycorrhizal dependency experiments. The laboratory portion of a research study using molecular technique (TRFLP) to characterize mycorrhizal fungi in plant roots was completed. Seedlings were planted into a second year field experiment and fungicide treatments were applied. A study was expanded to include growth room experiments testing effects of mycorrhizae on growth of two dominant plants and another testing the effects of field soil, field soil and fungicide, and sterilization of field soil on growth of two dominant plants. Two mine restoration projects were initiated. To relate plants to measures of soil health, water infiltration measurements were collected; soil wedges were collected to determine water stable aggregates; and soil cores were collected to determine soil carbon, root mass, and bulk density. Projects describing the direction and magnitude of soil feedback effects of mixed-grass prairie species and comparison of various predictors of plant mycorrhizal dependency were completed.
1. Management adjustments for range livestock producers during drought. Early weaning is a potential strategy to reduce rangeland forage intake during drought. ARS researchers at Miles City, MT completed a study investigating the effects of early weaning (80 days of age) on cow-calf performance. Data from the study indicate that when properly managed, early weaning did not have negative impacts on young or older cows, on subsequent reproduction in early-weaned heifer calves or in early-weaned steer calf performance. Weaning calves early can reduce forage intake by up to 30%, allowing conservation of available forages, and help to maintain the genetic background of a producer’s livestock that they have spent years developing.
2. Restoration success of weed-invaded grassland. Introductions of native and desirable non-native plants into weed-dominated grasslands have been attempted, but their likelihood of persisting and suppressing weeds for the long term is unknown. ARS researchers at Miles City, MT measured plant abundance for nine and 15 years at two seeded sites. Data from the first three years after seeding often falsely suggested seeded species were capable of persisting and data from as late as nine years after seeding falsely suggested seeded populations would not become large enough to suppress the invader. Seeded species sometimes persist and suppress invaders for long periods, but short-term data were not accurate predictors of final results. Long-term data are needed to identify effective practices, traits, and species for restoring weed-invaded grasslands.Rinella, D.J., Wipfli, M.S., Sticker, G.A., Heintz, R.A., Rinella, M.J. 2012. Salmon returns and consumer fitness: growth and energy storage in stream-dwelling salmonids increases with spawning salmon abundance. Canadian Journal of Fisheries and Aquatic Sciences 69:73-84.