Seasonal variation of leaf traits in a chaparral/ coastal sage scrub environment
Mentor:Louis Santiago, Asst. Prof. of Physiological Ecology, University of California Riverside
Understanding how plants tolerate and react to shifting climate patterns, especially drought, is critical with respect to agriculture and brushfire incidence. It is recognized that within the same climate, plant species can vary dramatically in drought tolerance. We characterize the variation of leaf traits in a Mediterranean climate to determine whether leaf morphological traits are related to drought tolerance and flammability. There are three distinct strategies that indigenous species use to regenerate following fire. Obligate sprouters always respond to fire by producing re-sprouts from root storage tissue. Non-sprouters always regenerate after fire through a seedbank of fire-resistant seeds. Facultative sprouters have the ability to re-sprout following fire, but may also produce seeds. We measured specific leaf area (SLA), leaf dry matter content (LDMC), and relative water content (RWC) on fourteen native Californian shrub species from the Santa Margarita Ecological Reserve. Obligate sprouters had greater SLA and RWC than non-sprouters and facultative sprouters. There were no differences in LDMC among species. The data indicate that because obligate sprouters maintain a greater RWC during seasonally-dry summers, they appear less flammable and potentially greater drought tolerance. The data also indicate that greater SLA in obligate sprouters is likely related to leaves with greater physiological capacity according to the leaf economics spectrum. Further work needs to be done to understand linkages between regeneration strategies, flammability and the leaf economics spectrum.