After 5 years of drought, southern California has recently experienced increases in precipitation. Malosma laurina is a chaparral shrub that displays vulnerability to fungal infection during severe drought conditions, particularly in its adult branches, resulting in severe dieback throughout the Santa Monica Mountains. M. laurina is known to produce resprout leaves during times of environmental stress that are less affected by the fungus based on its ability to maintain water status and thus are more capable of displaying resilience in more favorable environmental conditions. We hypothesize that the increase in rain will not be enough to alter the vitality of the resprout leaves of M. laurina, as determined through physiological values and water potential. To test this hypothesis, we measured the rate of photosynthesis, ETR, ΦPSII, and water potential of adult and resprout M. laurina and compared our data to measurements taken in 2015. We found that the physiological measurements obtained using Li 6400 XT and the water potential obtained using a Scholander Pressure Chamber were both significantly different from 2015 measurements. With these results, we rejected our hypothesis and concluded that the rain has had a positive effect in increasing the vitality of the resprout plants.
Jessen, Nicolette; Van Fleet, Kirstin; and White, Rachel, "Comparison of Physiological Measurements and Water Potential of Malosma laurina During and after the Drought in Southern California" (2017). Pepperdine University, Featured Research. Paper 179.