Location: Range and Meadow Forage Management Research
2020 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
This is the final report for project 2070-22000-005-00D, “A Systems Approach to Restoring Invaded Sagebrush Steppe,” which has been replaced by bridging project 2070-22000-006-00D.
Relative to Sub-objective 1A, scientists at Burns, Oregon, have conducted several studies aimed at enhancing emergence and survival of desired restoration species by selecting seeds that have greater mass. We tested several ideas for enhancing the quality of seeds produced for restoration. Species with the most photosynthetic reproductive parts have the highest quality seeds. These scientists finalized a seed quality manuscript documenting this important phenomena.
In support of Sub-objective 1B, ARS scientists at Burns, Oregon, have conducted a series of studies aimed at improving our ability to establish desired species by broadcasting seeds onto rangeland sites that are disturbed and infested with weeds. Since safe sites for seeds are dynamic, we have monitored safe site characteristics by taking repeated photographs of permanent plots over three years at two locations composed of typical sagebrush steppe. This year, our team has uploaded these photographs and began initial analysis to identify periods when special safe sites appear to be most available for seeds and to quantify the size and shape of those safe sites in preparation for manuscript development. In addition, our team has conducted a study aimed at testing the relationship among safe site availability and seeding rate. Using a purely experimental approach, we tested the efficacy of various physical safe-site sizes and shapes with multiple seed sizes and seed numbers to quantify the ability to improve seedling establishment during restoration. These two combined studies will allow land managers to improve seedling establishment by matching safe-site availability with choice of species to be broadcast seeded. Scientists at Burns, Oregon, have analyzed these data and have prepared draft manuscripts for publication. This team has also initiated the development of a decision-tool for land managers this year. Overall, this project is completed except for submitting manuscripts.
In support of Sub-objective 1C, scientists have conducted several experiments to help understand the relationship among seedling herbivory, soil moisture, and plant density during restoration. Our team has published three manuscripts on this topic and collected the data required to determine the relationship between rodent/insect herbivory and restoration success across the northern Great Basin. These scientists collected the final set of data for this study and have incorporated the results into the demographic model. This project has been completed and described in the accomplishment section.
In support of Sub-objectives 2A and 2B, scientists at Burns, Oregon, have developed and parameterized a life-history model for predicting population dynamics of key grasses found in the Shrub-Steppe rangelands of the northern Great Basin. This team has also incorporated data from the current research into the model. This new model is undergoing a comprehensive validation procedure and then will be released to stakeholders for comments on improvement.
Accomplishments
1. Reproductive photosynthesis regulates viable seed production. Land managers throughout the western United Sates focus on maintaining self-replacing, stable bunchgrass populations because this is the most effective method to restore sagebrush steppe rangelands degraded by invasive annuals. Researchers at Burns, Oregon, found that rangeland grasses capable of consistently producing viable seed cohorts possessed seed heads with higher photosynthetic capacity and efficiency than those with lower reproductive capability. These reproductive functional attributes will improve how we select and develop new plant material by guiding plant researchers and managers toward those traits that enhance reproductive success of perennial grasses, thereby improving restoration success in sagebrush steppe rangelands.
2. Choosing species that are tolerant of defoliation at the seedling stage during seeding. Federal and state agencies, as well as private land owners, are struggling to establish seedlings of desired species on degraded and invaded rangeland. Defoliation of seedlings, the removal of plant leaf material the plant requires for successful growth, is often caused by insects and rodents. In a series of investigations, researchers in Burns, Oregon, found that crested and bluebunch wheatgrass can survive even two defoliation events if they are at a moderate level (about 30% of the plant is removed). However, Sandberg’s bluegrass suffered substantial losses with a single moderate level of defoliation. It appears that the larger bunchgrasses can survive substantial defoliation as seedlings by increasing photosynthetic rate. Land managers can select defoliation tolerant species during restoration of land with uncontrollably large populations of herbivores (rodents and insects).
3. Snowfall determines seedling establishment during restoration. Land managers throughout the western United States are trying to restore annual grass-invaded grassland to perennial grasses. Grass plant populations must be able to reseed if they are to maintain themselves over time. Models of climate change indicate that the amount of snowfall will likely decrease as temperatures increase. Researchers in Burns, Oregon, tested the effects of snowfall amount on seedling establishment in a cold desert ecosystem. They found low snowpack increased the intensity of freeze-thaw cycles and fungal pathogen infection, reduced soil moisture during critical periods of seedlings development, and increased soil penetration resistance. As new weather forecasting applications are applied to restoration projects, years with high snowfall forecasts will be identified as good years for attempting seedings. Also, new seed coatings are being developed to enhance seedling establishment. This research shows coating that help seeds overcome droughty conditions during years with low snowfall, will be critically helpful to restoring degraded and invaded rangeland.
4. Biotic interactions, rather than abiotic, control annual grass dominance. Annual grasses pose a major threat to rangeland throughout the western United States. Novel restoration methods will likely evolve from increased knowledge about the factors driving invasion. ARS researchers in Burns, Oregon, conducted a field assessment of 100 climate, soil, and biotic (functional group abundances, diversity) factors at each of 90 sites that spanned an invasion gradient ranging from 0 to 100 % annual grass cover. They first determined which biotic and abiotic factors had the strongest correlative relationships with annual grass and each resident functional group. The structural equation model showed negative effects of perennial grasses and biodiversity on annual grass cover, while integrating the negative effects of warmer climate and positive influence of belowground processes on resident functional groups. The findings illustrate the relative importance of biotic interactions, especially perennial grass competition and climate on invasive abundance, while soil properties appear to have stronger relationships with resident biota than with invasives. This is critical information for developing ecologically-based annual grass management systems and will lead to new innovations in their management.
5. User-friendly economic assessment of rangeland prevention programs. Understanding the cost-benefit ratio of prevention programs is essential to design impactful invasive weed management programs. ARS researchers in Burns, Oregon, developed an easy-to-use economic model to assess potential savings in livestock forage that might result from implementing prevention programs. The model can be used to determine potential loss in forage production caused by invasive plants and to estimate potential income savings by preventing invasive plant infestations. The model suggests that as the Animal Unit Month (AUM) price increases and/or the interest rate decreases, the total savings increases for each AUM that was protected through a prevention program. The model also shows savings per AUM increases as the size of the initial infestation decreases, suggesting that prevention should focus on eliminating seed sources and seed production early in the program. Using the model inputs, the savings per AUM was about $9.20 for each percent reduction in spread rate over a 100 year period. For the first time ever, land managers can assess the cost effectiveness of their invasive plant prevention programs for individualized programs.
6. High seeding rates enhances seedling establishment and reduce annual grass abundance. Restoring arid regions degraded by invasive annual grasses to native perennial grasses is a critical conservation goal. ARS researchers in Burns, Oregon, evaluated the independent and combined inputs of tilling, burning, applying imazapic herbicide, and varying seeding rates on existing species and seeded native perennial grass performance from 2008 to 2012 in a southwestern Idaho rangeland ecosystem. They found that combining tilling, fire, and herbicides produced the highest grass establishment and lowest annual grass cover. This system provides land managers with a viable method for restoring annual grass infested rangeland.
Review Publications
Hamerlynck, E.P., Denton, E.M., Davies, K.W., Boyd, C.S. 2019. Photosynthetic regulation in seed heads and flag leaves of sagebrush-steppe bunchgrasses. Conservation Physiology. 7(1):coz112. https://doi.org/10.1093/conphys/coz112.
Hamerlynck, E.P., Ziegenhagen, L.L. 2020. Seed head photosynthetic light responses in clipped and unclipped sagebrush steppe bunchgrasses. Journal of Arid Environments. 172. https://doi.org/10.1016/j.jaridenv.2019.104013.
Dusza, Y., Sanchez-Canete, E.P., Le Galliard, J., Ferriere, R., Chollet, S., Massol, F., Hansart, A., Juarez, S., Dontsova, K., Van Haren, J., Troch, P., Pavao-Zuckerman, M.A., Hamerlynck, E.P., Barron-Gafford, G.A. 2020. Biotic soil-plant interaction processes explain most of hysteric CO2 efflux response to temperature in cross-factorial mesocosm experiment. Scientific Reports. 10:905. https://doi.org/10.1038/s41598-019-55390-6.
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.
Chambers, J.C., Maestas, J.D., Pyke, D.A., Boyd, C.S., Pellant, M., Wuenschel, A. 2017. Using resilience and resistance concepts to manage persistent threats to sagebrush ecosystems and greater sage-grouse. Rangeland Ecology and Management. 70(7):149-164. https://doi.org/10.1016/j.rama.2016.08.005.
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.
James, J.J., Sheley, R.L., Leger, E.A., Adler, P.B., Hardegree, S.P., Gornish, E.S., Rinella, M.J. 2019. Increased soil temperature and decreased precipitation during early life stages constrain grass seedling recruitment in cold desert restoration. Journal of Applied Ecology. 56(12):2609-2619. https://doi.org/10.1111/1365-2664.13508.
Swanson, E.K., Sheley, R.L., James, J.J. 2019. Do shrubs improve reproductive chances of neighbors across soil types in drought? Oecologia. 192:79-90. https://doi.org/10.1007/s00442-019-04559-x.
Karl, J.W., Sheley, R.L., Levi, E., Brown, J. 2019. On conflict and conflict of interest. Rangeland Ecology and Management. 72(3):572-573. https://doi.org/10.1016/j.rama.2019.03.008.
