Sagebrush ecosystems are among the most widespread and imperiled in the United States. They provide essential ecosystem services and habitat for over 400 sagebrush obligate taxa. Ecological restoration is a process that can be utilized to repair damaged sagebrush ecosystems. However, this process can be expensive, and therefore it is important to utilize restoration protocols that have a high chance of restoring functional ecosystems. Local adaptation and phenotypic plasticity are two factors that affect the successful establishment of plants, and both have been linked to plant functional traits. Understanding the degree of these factors in plant species commonly used in restoration is vital for informing seed sourcing protocol and planning for anthropogenic climate change. We grew three accessions of Grindelia squarrosa, a plant commonly used in sagebrush restoration, in drought and well-watered conditions, measured various leaf functional traits, and developed A/Ci curves to better understand the effect of local adaptation and plastic responses to environmental conditions on productivity. We expect well-watered plants of all accessions to have higher photosynthetic rates and stomatal conductance. We expect this will correspond to a higher Vcmax (rubisco limited photosynthesis) and J (Ribulose-bisphosphate regeneration limited photosynthesis).
Results/Conclusions
Preliminary data show different phenotypic characteristics based on accession and water treatment, suggesting seed harvesting location may affect the success of restoration. Drought plants had smaller, thicker leaves compared to well-watered plants. Well-watered plants had higher stomatal conductivity compared to drought treated plants. However, watering treatment did not affect maximum photosynthetic rate. Accession did have a significant impact on productivity. Two accessions responded similarly to watering treatments, with mean Vcmax and J higher in wet treatments. However, the third accession exhibited an interaction, in which maximum photosynthetic rate, vcmax, and j, decreased in wet treatments. This interaction could be an indication of local adaptation in this population, in which optimal soil moisture conditions are drier compared to the other accessions. When comparing this to climatic variables, this accession was collected at the lowest elevation, driest, warmest site with the most variability in temperature. This suggests that this accession may be better adapted to hotter, drier, more stressful conditions.