High levels of both abiotic and biotic stresses (eg. water stress, competition from invasive species) challenge the establishment of native species in CA coastal grassland restoration, leading many practitioners across the state to rely heavily on seven “high-success” perennial species despite the vast diversity of annual and perennial species that are native, or even endemic, to this ecosystem. In this study, we set out to facilitate use of a greater subset of native species diversity in coastal grassland restoration by comparing rarely-used and commonly-used grass and forb species in their ability to survive drought. We are assessing drought survival for 17 rarely-used annual and perennial species chosen by restoration practitioners in the Grassland Restoration Action Science and Stewardship Network (GRASS-Net - see below) and 5 of the “high-success” perennial species commonly used in restoration. Using a greenhouse study, we are imposing a lethal drought treatment to quantify the lethal drought index (LD50): the drought threshold associated with 50% population mortality (sensu Barkaoui and Volaire 2023), for each species. Using multivariate and linear statistical approaches, we are assessing relationships of a suite of functional, physiological, and growth traits to LD50, including specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC), turgor loss point (πtlp), meristematic water content at LD50 (MWC), ratio of senesced to green leaves at LD50 (LS50), and drought severity at stomatal closure (gs0). Overall, this work develops our understanding of a suite of novel drought tolerance thresholds, connecting them to well-established characterizations of plant physiology and providing needed information for grassland restoration practitioners in California. 

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