The long-term objective of this project is to develop practices and strategies to restore and conserve Great Basin rangelands. Specifically, during the next five years we will focus on the following objectives: Objective 1 (Restoration): Develop practices and strategies for restoring perennial livestock forages and ecosystem function on degraded and fire-prone Great Basin rangelands using combinations of grazing management, vegetation treatments, seed enhancements, and traditional restoration techniques. Subobjective 1A: Develop seed enhancement technologies for overcoming barriers to rangeland seeding success. (Davies, Boyd, Copeland) Subobjective 1B: Determine appropriate seed mixes for use after wildfires to limit exotic annual grass invasion and restore productivity. (Davies, Boyd, Copeland) Subobjective 1C: Develop and evaluate management practices for controlling juniper encroachment of sagebrush steppe plant communities. (Bates, Davies) Subobjective 1D: Determine post-treatment change in vegetation composition and structure over a 30 year time horizon in cut compared with burned juniper-encroached sagebrush steppe. (Boyd, Bates, Davies) Objective 2 (Conservation): Develop practices and strategies (including decision-support tools) to maintain and enhance livestock forage production and other ecosystem services in rangelands across different site characteristics, climate conditions, and management systems. Subobjective 2A: Evaluate grazing management as a tool to decrease wildfire risk, behavior, and severity. (Davies, Bates, Boyd, Copeland) Subobjective 2B: Evaluate post-fire grazing management effects on herbaceous productivity and sage-grouse habitat. (Bates, Davies) Subobjective 2C: Determine the influence of site attributes and climate variation on long-term productivity and diversity of sagebrush steppe. (Bates, Davies, Copeland) Subobjective 2D: Develop a science-based framework for management planning. (Boyd, Bates, Davies)
Objective 1: Hypotheses: 1) Incorporating seeds into activated carbon pellets will protect seeded vegetation from pre-emergent herbicides, 2) Seeds treated with abscisic acid will have delayed germination and increased seedling density relative to non-coated seeds, 3) Coating and imbibing treatments will produce similar seedling densities, 4) The effects of abscisic acid treatment will be dependent on level of coating; based on previous lab work we hypothesize that intermediate levels of treatment will produce highest seedling densities, 5) Drill seeding a mixture of native and introduced bunchgrasses after wildfire in sagebrush steppe will reduce exotic annual grass invasion compared to seeding native bunchgrasses, seeding introduced bunchgrasses, and not seeding, 6) Burning juniper-encroached sagebrush steppe will increase desirable herbaceous production, 7) Herbaceous vegetation productivity and abundance will be greater when juniper is controlled with either fall broadcast burning treatment or clear-cut/slash burning treatment compared to untreated woodlands, 8) Clear-cut/slash burning of encroaching junipers will produce more favorable habitat characteristics for sage-grouse compared to fall broadcast burning, 9) Juniper cover and density will increase at a faster rate in cut vs. burned western juniper plant communities, 10) Cover and density of mountain big sagebrush will decrease in association with burning but will recover to levels in cut treatments within 30 years, 11) Rate of increase in density and cover of large perennial bunchgrasses will be faster in burned vs. cut treatments, and 12) exotic annual grasses will initially increase more in the burned compared to the cut treatment. Objective 2:Hypotheses: 1) moderate livestock grazing compared to grazing exclusion will reduce fine fuel continuity, height, total biomass, and accumulation of residual biomass on perennial grass crowns and 2) decrease fire-induced mortality of perennial grasses and thereby reduce post-fire exotic annual grass invasion, 3) increasing grazing pressure will reduce fuels and thereby decrease fire ignition potential and propagation, 4) Long-term heavy rotational grazing after fire will decrease herbaceous productivity, sage-grouse dietary forbs, and horizontal screening cover compared to light, moderate, and no grazing treatments, and 5) No grazing and light grazing will have greater herbaceous productivity, sage-grouse dietary forbs, and horizontal screening cover than moderate grazing. Experimental approaches and research procedures: We will use a combination of grow room studies and small and large replicated field studies to answer these research questions. Many of these field studies will be long-term studies. If initial research plan is unsuccessful, we will revise our grow room and field studies to address the reasons why our initial research plan was unsuccessful or replicate the original experiment if it was unsuccessful because of an act of nature.
This report is for this new project which began in March of 2019, and continues research from the bridging project 2070-21630-002-00D, "Restoring and Managing Great Basin Ecosystems." For Objective 1, ARS scientists in Burns, Oregon, set up and collected data on grow room and field plot experiments designed to test the effectiveness of activated carbon pellets at protecting seeds from pre-emergent herbicide damage. Burns scientists also set up plots to evaluate coating and imbibing seeds with abscisic acid to delay germination. The scientists and support staff collected data on experiments evaluating drill seeding native compared to non-native grasses after wildfire and performed experiments investigating the effects of burning juniper on herbaceous production. They identified and sampled areas that had either been cut or burned in the last 30 years to control western juniper to determine post-treatment vegetation recovery and juniper re-encroachment rates between these two commonly applied treatments. For Objective 2, the scientists continued to collect data on experiments to evaluate grazing management as a tool to decrease wildfire risk, behavior, and severity. The ARS scientists continue to apply treatments and collect data on the effects of grazing after fire in sagebrush steppe communities. The scientists have also prepared peer-reviewed manuscripts on the long-term variability in vegetation characteristics in Wyoming big sagebrush communities. They continue to develop management-oriented materials to guide rangeland management based on ecological threats and the influence of management and non-management factors on plant community change.
1. Prescribed fire to control juniper in shrub-steppe communities. The sagebrush ecosystem is facing unprecedented ecosystem-level management challenges. On mid- to high-elevation rangelands across the sagebrush biome, populations of native conifer species are expanding in association with increased fire return intervals, reducing or eliminating understory grasses and shrubs, and leading to severe impacts on forage availability for rangeland agriculture as well as habitat for imperiled sagebrush-associated wildlife species. Cutting is often used to control expanding juniper, but is expensive, and results may be of only limited duration, whereas prescribed fire economically removes mature and seedling juniper, and has a longer duration of effect, but at the expense of temporarily eliminating habitat for sagebrush wildlife and increasing the risk of annual grass invasion. ARS scientists in Burns, Oregon, worked with Oregon State University and The Nature Conservancy to conduct a retrospective study that estimated level and duration of juniper control for cutting versus fire across the northern Great Basin region. Results from this work indicate that prescribed fire was more effective than cutting at controlling encroaching juniper in imperiled shrub-steppe communities, and counter to general assumptions, burned areas did not have more annual grass cover than cut areas. This suggests that prescribed fire is a valuable ecosystem tool to meet conservation objectives in shrub-steppe communities.
Davies, K.W., Bates, J.D., Boyd, C.S. 2019. Post-wildfire seeding to restore native vegetation and limit exotic annuals: an evaluation in juniper-dominated sagebrush steppe. Restoration Ecology. 27(1):120-127. https://doi.org/10.1111/rec.12848.
Bates, J.D., Davies, K.W., Bournoville, J., Boyd, C.S., O'Connor, R., Svejcar, T.J. 2019. Herbaceous biomass response to prescribed fire in juniper-encroached sagebrush steppe. Rangeland Ecology and Management. 72(1):28-35. https://doi.org/10.1016/j.rama.2018.08.003.
Davies, K.W., Boyd, C.S. 2019. Ecological effects of free-roaming horses on North American rangelands. Bioscience. 69(7):558-565. https://doi.org/10.1093/biosci/biz060.
Bates, J.D., Davies, K.W. 2019. Characteristics of intact Wyoming big sagebrush associations in southeastern Oregon. Rangeland Ecology and Management. 72(1):36-46. https://doi.org/10.1016/j.rama.2018.07.015.
Clenet, D.R., Davies, K.W., Johnson, D.D., Kerby, J. 2019. Native seeds incorporated into activated carbon pods applies concurrently with indaziflam: a new strategy for restoring annual-invaded communities? Restoration Ecology. 27(4):738-744. https://doi.org/10.1111/rec.12927.
Davies, K.W., Hamerlynck, E.P. 2019. Ventenata and other coexisting exotic annual grass control and plant community response to increasing imazapic application rates. Rangeland Ecology and Management. 72(4):700-705. https://doi.org/10.1016/j.rama.2019.02.010.
Davies, K.W., Dean, A.E. 2019. Prescribed summer fire and seeding applied to restore juniper-encroached and exotic annual grass-invaded sagebrush steppe. Rangeland Ecology and Management. 72(4):635-639. https://doi.org/10.1016/j.rama.2019.03.006.
Copeland, S.M., Munson, S.M., Bradford, J.B., Butterfield, B.J., Gunnell, K.L. 2019. Long-term plant community trajectories suggest divergent responses of native and non-native perennials and annuals to vegetation removal and seeding treatments. Restoration Ecology. 27(4):821-831. https://doi.org/10.1111/rec.12928.
Hamerlynck, E.P., Davies, K.W. 2019. Changes in abundance of eight sagebrush-steppe bunchgrass species 13 yr after coplanting. Rangeland Ecology and Management. 72(1):23-27. https://doi.org/10.1016/j.rama.2018.07.001.
Davies, K.W., Bates, J.D. 2019. Longer term evaluation of sagebrush restoration after juniper control and herbaceous vegetation trade-offs. Rangeland Ecology and Management. 72(2):260-265. https://doi.org/10.1016/j.rama.2018.10.006.