Research Project: A Systems Approach to Restoring Invaded Sagebrush Steppe

Location: Range and Meadow Forage Management Research

2019 Annual Report

Objectives
The first and primary research goal of this project is to improve our systems approach to restoration for annual grass management in the sagebrush steppe of North America. In 2013, we provided a systems approach that advances ecological restoration beyond conceptual and phenomenological descriptions to quantitative process-based models that can be used to address specific applied questions (James et al. 2013a). Our systems approach uses life histories to identify transitions important to seedling establishment and maturation. It links those transitions to ecological processes directing establishment and management practices that can favorably impact those processes. Our technology transfer goal is to use the research results for developing tools aimed at assisting land managers in selecting seeds based on their quality, guidelines for determining when and what species to broadcast during restoration, and guidelines on assessing and managing defoliation of newly emerged seedlings at risk to herbivory. Specifically, during the next five years we will focus on the following objectives: Objective 1: Enhance rangeland restoration processes by improving the establishment of seedlings of desirable plant species (such as increasing seed quality and seedling survival), acquiring and implementing basic knowledge to match naturally occurring physical safe-sites with seed traits, identifying and quantifying the effects of herbivory on seedling survivorship, and developing threshold guidelines for mitigation. Sub-objective 1A: Improve rangeland restoration success by enhancing seed quality and emergence survival of desired restoration species and develop simple seed quality selection criteria. Sub-objective 1B: Develop the basic knowledge to match naturally occurring physical safesites with seed traits to maximize seedling establishment during restoration. Sub-objective 1C: Identify and quantify the effects of herbivory on seedling survivorship to develop threshold guidelines for mitigation during restoration. Objective 2: Integrate research into an ecological systems approach to restoration with current cost/benefit models and link to site-specific best management practices. Sub-objective 2A: Develop decision-support tools for 1) choosing seeds based on quality characteristics, 2) matching seed size, number, and physical safe-site availability during restoration, and 3) identifying and managing risk to seedlings associated with herbivory. Sub-objective 2B: Inform and update our systems approach to include important aspects of seed quality, maximizing physical safe-site capture, and minimizing seedlings risk of herbivory and link this model with existing cost/benefit models.

Approach
Rangelands cover nearly one-half of the earths land surface and provide life sustaining goods and services to about one-third of the global population. Low and variable rainfall combined with often infertile soil make the world’s rangelands highly susceptible to degradation, invasion, and global climate change (Millennium Ecosystem Assessment 2005). The inability to establish healthy plant communities is cited by stakeholders as the single largest barrier to implementing restoration and turning the tide against the hundreds of thousands of hectares of sagebrush steppe lost to invasive plants each year. Despite over a century of research, rangeland science lacks a comprehensive understanding of the ecological processes influencing seedling establishment. The goal of this project is to improve restoration for annual grass management in the sagebrush steppe of North America. Using a series of field and laboratory tests, our first study attempts to improve rangeland restoration success by enhancing seed quality and emergence survival of desired restoration species and develop simple seed quality selection criteria. Our second study is aimed at developing the basic knowledge to match naturally occurring physical safe-sites with seed traits to maximize seedling establishment during restoration. Third, we plan to identify and quantify the effects of herbivory on seedling survivorship to develop threshold guidelines for successful restoration. Finally, we will integrate this research into an ecological systems approach to restoration with current cost/benefit models. Strong emphasis will be placed on operationalizing research knowledge and products through our existing outreach program and strengthening outreach through direct support of parallel efforts by Oregon State University. To maximize benefit to a diversity of customers, outreach will target and support numerous regional collaborative management groups.

Progress Report
Progress was made on all objectives and their sub-objectives. For Sub-objective 1A, we repeated our experiments determining the effects of fall versus spring dormant season burning on bluebunch wheatgrass seed quality (mass) with more powerful ability to detect differences. The first season of post treatment seeds are being collected this month. A paper reporting the results of the initial experiment is being prepared. Lastly, we completed field studies confirming variable reproductive success of rangeland bunchgrasses is related to seed head photosynthetic performance. Sub-objective 1B aims to match naturally occurring physical safe-sites with seed traits to maximize seedling establishment on shrub steppe in need of restoration. All of the field sampling has been completed and these data are compiled into appropriate software for analysis. Quantification of cracking via photographic record and post analysis is nearly completed. These photographs will be used as the basis for future guidelines to help land managers assess soil surface characteristics for broadcasting seeds during restoration. Data are ready for analysis and processing for use in subsequent publications. Sub-objective 1C, the effects of herbivory on newly established seedlings under actual field conditions is aimed at helping producers predict how the probability of small rodent and insect herbivory impact emerging seedlings during restoration. We have carefully monitored about 45 restoration sites each spring in Oregon, Idaho and Nevada. This spring, we set-up our exclusion experiment and monitored them on 12 field restoration seedings. Mammal activity that might result in herbivory was quantified at each site using a combination of camera traps and surveys that quantified evidence of herbivore presence. Insect activity was quantified using grasshopper surveys and drench tests to capture soil dwelling insects. Also under Sub-objective 1C, seedling survival data from an experiment studying how seedlings were impacted in response to five clipping treatments (no defoliation, 30% defoliation once, 30 percent defoliation twice, 70 percent defoliation once, 70 percent defoliation twice) was analyzed. A paper reporting the results of this experiment is being prepared. With respect to Objective 2A, we have initiated the process of drafting guidelines and the ranking tool has been designed and formulated, but these data are just available for this year and will be used to inform the ranking tool in the next two months.

Accomplishments
1. Advancing restoration of Western rangeland. Across most of the western U.S., native plant communities are being displaced by monocultures of annual invasive grasses. These non-native species destroy habitat for livestock and wildlife and cause frequent and intense wild fires that now plague the region, making it imperative that such degraded and invaded areas be restored to healthy and functional plant communities. ARS researchers in Burns, Oregon, developed a systems approach to sagebrush rangeland restoration that moves ecological restoration beyond conceptual descriptions to quantitative process-based models that can be used to address site-specific plant establishment limitations. This knowledge will assist land managers in restoring millions of acres of invaded sagebrush steppe rangeland back into healthy native functioning ecosystems.

Review Publications
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.
Hardegree, S.P., Sheley, R.A., Brunson, M.W., Taylor, M.H., Moffet, C.A. 2019. Iterative-adaptive management and contingency-based restoration planning in a variable environment. Rangeland Ecology and Management. 72(2):217-224. https://doi.org/10.1016/j.rama.2018.09.006.
Schantz, M., Hardegree, S., Sheley, R. 2018. Restoring native perennial grasses in medusahead habitat: Role of tilling, fire, herbicides, and seeding rate. Rangeland Ecology and Management. 72(2):249-259. https://doi.org/10.1016/j.rama.2018.10.012.
Moffet, C., Hardegree, S.P., Abatzoglou, J.T., Hegewisch, K.C., Reuter, R., Sheley, R.L., Brunson, M.W., Flerchinger, G.N., Boehm, A.R. 2018. Weather tools for retrospective assessment of restoration outcomes. Rangeland Ecology and Management. 72(2):225-229. https://doi.org/10.1016/j.rama.2018.10.011.
Hardegree, S.P., Roundy, B., Walters, C.T., Reeves, P.A., Richards, C.M., Moffet, C., Sheley, R.L., Flerchinger, G.N. 2018. Hydrothermal germination models: assessment of the wet-thermal approximation of potential field response. Crop Science. 58(5):2042-2049. https://doi.org/10.2135/cropsci2017.11.0666.
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.
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.
Vasquez, E.A., Sheley, R.L. 2018. Developing diverse, effective, and permanent plant communities on reclaimed surface coal mines: restoring ecosystem function. Journal of the American Society and Mining and Reclamation. 7(1):77-109. https://doi.org/10.21000/JASMR18010077.