Project : USDA ARS

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Research Project: Integrate Vegetative Bud-based Propagation and Seeds in Restoration of Rangeland Native Plant Communities

Location: Range and Meadow Forage Management Research

2025 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 report documents progress for project 2070-22000-000D titled, “Integrate Vegetative Bud-based Propagation and Seeds in Restoration of Rangeland Native Plant Communities”, which started in March 2021. To extend and support Objective 1, ARS researchers in Burns, Oregon, are creating a user’s guide to the harvesting and storage of vegetative buds of select rangeland bunchgrasses and a manuscript on the best time of year and amendments to enhance establishment of bluebunch wheatgrass or Sandberg’s bluegrass from buds. In support of Objective 2, vegetative material (biomass) from plots for comparing plant establishment from buds versus seeds has been collected for this second and final year. Any reproductive material produced by the plants was counted and weighed as well. Plants sown last year from harvested buds were collected. All vegetative material is being weighed now for comparison. Finally, in support of Sub-objectives 3A and 3B, to compare life histories and physiological differences in bluebunch wheatgrass and Sandberg’s bluegrass growing as buds versus seeds, ARS researchers collected density data at key life history in spring, late spring, and summer. These data are now being incorporated into life history models. Eco-physiological studies examining variation in photoprotective mechanisms of reproductive structures of bluebunch wheatgrass and other perennial bunchgrasses were performed.

Accomplishments
1. Harvesting, storing and growing several perennial grass buds for use in restoration is possible. For vegetative materials to be available for use in restoration of degraded rangeland invaded by invasive weeds, they must be collectable and storable until they are needed. Further, plants must grow from crown buds after being sown. ARS researchers in Burns, Oregon, have created a system for harvesting perennial grass buds in moderate quantities by scalping the crowns through their mid-section and sifting away soil while extracting buds. These buds also remained dormant but viable in various cold room temperatures for over 6 months. They also discovered that the ability to grow new plants from sown buds depends on species. Sandbergs bluegrass, and Thurber’s needlegrass grew well from buds under optimal conditions. Bluebunch wheatgrass and bottlebrush squirreltail grew poorly from buds. Using vegetative bud material to augment seeds during seeding and restoration may be a viable technique for some species.

2. Effects of grazing on vegetative propagation potential. Livestock grazing can result in distinct differences in perennial bunchgrass growth and allocation patterns compared to those in ungrazed populations. Such differences could affect the usefulness of vegetative propagation as a method for restoration efforts in degraded sagebrush steppe rangelands. To address this, ARS scientists in Burns, Oregon, compared bud-derived tiller emergence number and time from harvesting in three important native bunchgrasses (Sandberg's bluegrass, bluebunch wheatgrass, bottlebrush squirreltail) to determine if total bud number or activity differed between grazed and ungrazed bunchgrasses. Results showed that in all three species long-term grazing imparted more rapid production of new shoots (tillers), but with the total number of tillers produced from bud similar between grazed and ungrazed populations. They found in all cases that that long-term grazing resulted in accelerated bud tillering activity, but that total bud activity was similar between grazed and ungrazed populations. Using buds collected from grazed plant population may enhance vegetative establishment.

3. Using geospatial advances to quickly and strategically develop a vision for post-fire management. Invasive annual grasses (IAG) are the leading cause of loss of intact sagebrush rangeland throughout the sagebrush biome and the continuous fuel bed conditions created by these species are associated with a dramatic increase in the frequency and extent of wildfire in sagebrush habitats, which in turn promotes increased IAG abundance. ARS researchers from Burns, Oregon, worked with Oregon State University and The Nature Conservancy to develop a threat-based strategic conservation framework that uses geospatial layers representing pre-fire plant community composition, likelihood of IAG invasion, and burn severity to quickly map a fire footprint into priorities areas for 1) maintaining largely IAG-free (pre-fire) habitats, 2) restoring areas moderately impacted by IAGs, and 3) containing IAG spread where pre-fire plant composition suggests the need for post-fire IAG containment. The ability to use recent geospatial advances to quickly and strategically develop a vision for post-fire management is a major milestone in changing the planning paradigm from reactive management of a crisis to strategic allocation of limited resources in support of ameliorating the IAG threat.

4. Mechanisms of reproductive compensatory photosynthesis. Seed production and seed quality are strongly linked to floral photosynthetic activity in arid land perennial bunchgrasses. While up-regulation of photosynthetic activity has been noted in response to floral herbivory in these grasses, the enzymatic mechanisms by which this compensatory response is attained are unknown. To address this, ARS scientists from Burns, Oregon, quantified the enzymatic regulatory mechanisms underlying compensatory reproductive photosynthesis responses to experimental floral herbivory. They found that partial floret removal increased photosynthetic enzymatic efficiency and capacity in directly affected florets, and that this served to enhance carbon provisioning to the remaining unaffected florets. Understanding these mechanisms may provide useful information for trait selection in developing novel and more effective perennial bunchgrass varieties.

U.S. DEPARTMENT OF AGRICULTURE

Range and Meadow Forage Management Research: Burns, OR