Project Number: 2070-22000-007-000-D
Project Type: In-House Appropriated
Start Date: Mar 3, 2021
End Date: Mar 2, 2026
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.
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.