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.
In support of Objective 1, ARS scientists in Burns, Oregon, 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 prepared peer-reviewed manuscripts on the effects of activated carbon pellets on seeded species. They also collected data on field plots designed 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 experiments investigating the effects of burning juniper on herbaceous production. ARS scientists prepared a manuscript that compared 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. The Burns scientists also prepared manuscripts on the effects of juniper treatments on plant community characteristics. In support of Objective 2, ARS scientists continued to collect data on experiments designed to evaluate grazing management as a tool to decrease wildfire probability, behavior, and severity. They also have prepared peer-reviewed manuscripts on the effects of pre-fire grazing on post-fire community recovery. Scientists continue to apply treatments and collect data on the effects of grazing after fire in sagebrush steppe communities. ARS 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. Recovery of the herbaceous component of sagebrush steppe unimpeded by 75 years of moderate cattle grazing. Understanding the long-term effects of cattle grazing on rangeland plant communities in big sagebrush steppe is important for managing both livestock forage resources and habitat for sensitive wildlife species such as sage-grouse. Without such knowledge, managers of millions of hectares of public and private rangeland must make assumptions about the effects of livestock grazing, and those assumptions are vulnerable to both litigation and alternate interpretations that favor other uses or values. Researchers in Burns, Oregon, evaluated how 75 years of moderate cattle grazing affects herbaceous vegetation in big sagebrush steppe communities in eastern Oregon that were historically intensively grazed by sheep. The results indicated that long-term herbaceous recovery and composition followed similar trajectories in moderately grazed and ungrazed sagebrush steppe. This suggests that moderate cattle grazing is compatible with sustainable management of herbaceous understory plants in sagebrush steppe. Additionally, they found that modern cattle grazing practices incorporating moderate levels of use were dissimilar to the negative effects of historical grazing practices. Therefore, management planning and resource assessment focused on herbaceous perennial communities in sagebrush steppe should seek to separate the impacts of historic livestock grazing from contemporary grazing practices.
Nafus, A.M., Svejcar, T.J., Davies, K.W. 2020. Native vegetation composition in crested wheatgrass in northwestern Great Basin. Rangeland Ecology and Management. 73(1):9-18. https://doi.org/10.1016/j.rama.2019.10.006.
Hartsell, J., Copeland, S.M., Munson, S., Butterfield, B., Bradford, J. 2020. Gaps and hotspots in the state of knowledge of pinyon-juniper communities. Forest Ecology and Management. 455(1). https://doi.org/10.1016/j.foreco.2019.117628.
Smith, J.T., Allred, B.W., Boyd, C.S., Carlson, J.C., Davies, K.W., Hagen, C.A., Naugle, D.E., Olsen, A.C., Tack, J.D. 2020. Are sage-grouse fine-scale specialist or shrub-steppe generalist? Journal of Wildlife Management. 84(4):759-774. https://doi.org/10.1002/jwmg.21837.
Davies, K.W., Boyd, C.S. 2019. Grazing is not binomial (i.e. grazed or not grazed): a reply to Herman. Bioscience Journal. 70(1):6-7. https://doi.org/10.1093/biosci/biz138.
Davies, K.W., Rios, R.C., Bates, J.D., Johnson, D.D., Kerby, J., Boyd, C.S. 2019. To burn or not to burn: Comparing reintroducing fire with cutting an encroaching conifer for conservation of an imperiled shrub-steppe. Ecology and Evolution. 9(16):9137-9148. https://doi.org/10.1002/ece3.5461.
Davies, K.W., Boyd, C.S., Bates, J.D., Hamerlynck, E.P., Copeland, S.M. 2020. Restoration of sagebrush in crested wheatgrass communities: a longer-term evaluation in the northern Great Basin. Rangeland Ecology and Management. 73(1):1-8. https://doi.org/10.1016/j.rama.2019.07.005.
Komatsu, K.J., Avolio, M.L., Lemoine, N.P., Isbell, F., Grman, E., Houseman, G.R., Koerner, S.E., Johnson, D.S., Wilcox, K.R., Alatalo, J.M., Anderson, J.P., Aerts, R., Baer, S.G., Bates, J.D., et al. 2019. Global change effects on plant communities are magnified by time and the number of global change factors imposed. Proceedings of the National Academy of Sciences. 116(36):17867-17873. https://doi.org/10.1073/pnas.1819027116.
Smith, M., Koerner, S., Knapp, A., Avolio, M., Chaves, F.A., Denton, E.M., Dietrich, J., Gibson, D.J., Gray, J., Hoffman, A.M., Hoover, D.L., Komatsu, K.J., Silletti, A., Wilcox, K., Yu, Q., Blair, J.M. 2020. Mass ratio effects underlie ecosystem responses to environmental change. Journal of Ecology. 108(3):855-864. https://doi.org/10.1111/1365-2745.13330.