Location: Range and Meadow Forage Management Research
2021 Annual Report
Objectives
The primary research goal of this project is to improve upon our previous systems approach to restore annual-grass-affected rangeland systems in the sagebrush steppe of North America. In 2013, we developed a systems approach that advanced ecological restoration practices from conceptual and phenomenological descriptions to quantitative process-based models that can be used to address specific applied questions. Our systems approach uses life history information to identify transitions from plant establishment through maturation and reproduction and links those transitions to the management of the ecological processes driving establishment and population growth. In our prior NP 304 project (July, 2015 to August, 2020), we are incorporating the effects of seed quality, safe-site availability, and seedling defoliation effects into our systems model for forecasting vegetation dynamics of sagebrush steppe ecosystems and are incorporating these factors into decision-support tools to guide managers in their planning and management. It is nearly impossible to reestablish native species from seeds in annual-grass invaded sagebrush steppe because seedlings struggle to break through the soil crust and survive the pulses of harsh weather conditions during establishment. In this project, we will test the potential to use growth buds harvested from crowns of native species to augment seed-based restoration efforts. Our pilot data suggests that plants growing from crown pieces that contain buds and growth primordia emerge faster than seedlings. The more substantial carbohydrate reserves of buds/primordia as compared to seeds may confer increased ability to survive harsh climatic conditions, such as those imposed by wet/dry weather pulses. Our objectives in the current project are to add critical information to our life history forecasting models and potentially provide a novel approach to restoring invaded sagebrush steppe ecosystems. Specifically, during the next five years, we will focus on the following:
Objective 1: Develop methods for harvesting, excavating, and storing buds and/or growth primordia and determine if buds and/or primordia (growth tissue around buds) of key caespitose grasses regenerate when placed in soil under near optimal conditions.
Objective 2: Quantify the environmental conditions under which buds/primordia outperform the emergence and growth of plants grown from seeds and assess the fitness (reproduction) of buds/primordia with and without seeds in comparison to seeds alone at several sites throughout the Great Basin.
Objective 3: Determine the physiological responses of buds/primordia and seeds to characterize the actual mechanism for enhanced or weakened emergence and/or survival during restoration.
Sub-objective 3A: Quantify and contrast the life histories of planted buds versus seeds.
Sub-objective 3B: Evaluate the physiological characteristics of plants established from buds versus seeds during restoration.
Approach
Because of the huge economic cost of seeding, the low probability of sown seeds establishing, and the vast amount of threatened sagebrush steppe rangeland, research scientists and managers have had to prioritize a subset of this ecosystem for restoration activities. Most restoration efforts of perennial rangeland plant communities focus on seeding-based methods; however, in established plant communities recruitment is often attributed to vegetative propagation from belowground meristems. In this project, we will test the potential to use growth buds harvested from crowns of native species to augment seed-based restoration efforts. To test the hypotheses that buds can be harvested and stored for a short period prior to sowing, whole crowns of bluebunch wheatgrass and Sandbergs bluegrass will be excavated and stored for zero, 3 weeks, and until spring as whole crowns in containers and placing containers in cold storage at a constant 2oC. After storage, buds will be placed in favorable conditions and grown for up to seven months to determine their viability. To test the hypotheses that seeds will produce more seedlings in moist environments, whereas buds will produce more seedlings in dry conditions, we will compare seedling establishment of bluebunch wheatgrass and Sandbergs bluegrass from seeds versus crown buds along a wide environmental gradient from hot/dry to cool/wet environments within a Sagebrush Steppe ecosystem. Lastly, we intend to quantify and contrast the life histories of planted buds versus seeds to determine the growth state and ecological processes associated with seedling success and failure and incorporate life history information into the existing systems approach to restoration model. Life histories of bluebunch wheatgrass and Sandberg bluegrass will be monitored in each plot described in the experiment for Objective 2. Individuals will be classified as one of the following life stages: emerged plants (1 or 2 leaves), juveniles (3+ leaves), individuals with multiple tillers, individuals with boot, individuals with inflorescence, and seed producing adults, and total seed output determined. Starting in the third year when plants have had time to mature, seed rain m-2 on the soil surface will be characterized. The soil seed bank m2 will be determined by sifting (2-mm sieve) a single randomly located soil sample before seed drop each year from each plot and that area excluded from future sampling. Survival probabilities will be estimated using Bayesian continuation ratio models to estimate the probabilities of transition between growth stages. Plant ecophysiological measurements will be made every two weeks at each location, concurrent with the life-history sampling described above. This will allow us to directly relate the effects of antecedent wintertime and growing-season soil moisture/temperature dynamics and plant ecophysiological performance to conditional probabilities of transitioning between different life stages by using them as priors for Bayesian continuation ratio models.
Progress Report
This is a new in-house project, which started in March 2021 and replaced expired project 2070-22000-006-00D. For more information, see the expired project report.
For Objective 1, we conducted two experiments aimed at developing methods for harvesting, excavating, and storing buds for use in restorations. In the first experiment, we evaluated whether a long-term storage method common in the horticultural industry for keeping bulbs for later planting could be transferred to successfully storing restoration materials consisting of the buds of perennial grass species: Sandberg bluegrass, bluebunch wheatgrass, tufted hairgrass, bottlebrush squirreltail and basin wildrye. Viability of buds stored with this cedar shavings/cold storage technique was checked over the course of four months after both a fall and spring harvest using both chemical staining for live tissue and growing out the vegetative material in a growth chamber. Data are currently being entered, and analysis will begin shortly.
We conducted additional research in support of Objective 1 involving a second experiment where wild-harvested bud material from four common perennial grass species (Sandberg bluegrass, bluebunch wheatgrass, tufted hairgrass and basin wildrye) was planted in pots in a grow room and each species’ potential to establish from vegetative material was accessed. In another experiment, we tested whether the addition of root growth hormone or nutrients could improve establishment success from buds. This was done using buds collected during both the fall and spring harvest for all species. Survival data over time and final below- and aboveground biomass data have been collected and entered into our database for analysis. Scans of root growth and branching were collected for a subset of individuals in an attempt to better understand root dynamics from buds.
Also relating to Objective 1, particularly determining ideal methods of harvesting, excavating, and storing buds and other primordia for use in restoration, we have drafted a manuscript reviewing all other research done to date on the ecology of bud growth and its potential to be used as a restoration material. The manuscript is currently undergoing revisions and will hopefully be published early next year.
While the large experiment laid out in Objective 2 is not set to begin yet, we are finalizing work on the preliminary study that will inform our experimental design. This preliminary study accesses the restoration potential of propagating desired perennial grass species from bud material harvested from adult plants versus using seeds from the same species over the course of two years and at two locations, with one fall and one spring planting in each year. Target species were Sandberg bluegrass, bluebunch wheatgrass, and bottlebrush squirreltail. We conducted the final fall planting in 2020 and assessed emergence and survival of individual plants over the course of this spring. We also followed up on individuals from previous fall and spring treatments to assess multi-year survival. Results of this experiment will inform the best planting times for our larger comparative bud versus seed experiment, which will be conducted over the spatial extent of the Northern Great Basin starting in 2022.
As a first step towards addressing Sub-objective 3A, we initiated an observational study monitoring the seasonality of bud production in wild populations of two desired restoration species, Sandberg’s bluegrass, and bluebunch wheatgrass. Bud, tiller and rhizome production is being accessed monthly to determine the phenology of these structures over the course of a year. This will allow us to develop the best harvest and planting regimes that fit the life histories of our target species as we progress toward developing buds as a restoration technology. Four months of data have been collected so far over an elevational gradient consisting of three sites. This monitoring will continue for an entire year.
Accomplishments
1. Including tiller buds with grass seeds may enhance restoration of Sagebrush Steppe ecosystems. The Sagebrush steppe ecosystem is in serious need of restoration, and seed-based seeding has not provided adequate emergence of native grasses. ARS research in Burns, Oregon, indicated that new plants initiated from tiller buds emerged in half the time as new plants developing from seeds at low temperatures (7 degrees C). This accelerated emergence persisted at warmer temperatures, though to a lesser extent. After 21 days, emergence was 8 times greater from tillers than from seed for bottlebrush squirreltail and 10 times greater for Sandberg bluegrass, two essential native grass species. Accelerated emergence could allow for greater restoration success in critical, but harsh ecosystems.
Review Publications
Allred, B.W., Bestelmeyer, B.T., Boyd, C.S., Brown, C., Davies, K.W., Duniway, M.C., Ellsworth, L.M., Erickson, T.A., Fuhlendorf, S.D., Griffiths, T.V., Jansen, V., Jones, M.O., Karl, J., Knight, A., Maestas, J.D., Maynard, J.J., McCord, S.E., Naugle, D.E., Starns, H.D., Twidwell, D., Uden, D.R. 2021. Improving Landsat predictions of rangeland fractional cover with multitask learning and uncertainty
. Methods in Ecology and Evolution. 12(5):841-849. https://doi.org/10.1111/2041-210X.13564.
Connell, R.K., O'Connor, R.C., Nippert, J.B., Blair, J.M. 2021. Spatial variation in soil microbial processes as a result of woody encroachment depends on shrub size in tallgrass prairie. Plant and Soil. 460:359-373. https://doi.org/10.1007/s11104-020-04813-9.
