A Comparison of Water Potential, Photosynthetic Rate, Electron Transport Rate, and Stomatal Conductance Between Native Malosma laurina and Exotic Schinus molle

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Research Poster

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Schinus molle is a relatively new invasive chaparral shrub in the Santa Monica Mountains and has only recently been observed to displace native shrubs like Malosma laurina. To investigate the probable cause of S. molle’s competitive displacement of M. laurina, we compared their water status, photosynthetic rates, electron transport rates, and stomatal conductance to water vapor diffusion during the fall months of 2016. We hypothesized that S. molle would physiologically outperform M. laurina indicated by higher photosynthetic rates, electron transport rates, stomatal conductance rates, and less negative water potential. We found that there was no significant difference between dry S. molle and dry M. laurina’s photosynthetic rates; however, the stomatal conductance of S. molle was significantly lower than M. laurina. This indicated higher water use efficiency meaning a greater amount of carbon gained for the amount of water lost. Additionally, the electron transport rate (ETR) was significantly higher for S. molle than M. laurina, suggesting efficient conversion of light to chemical energy in the light reaction of photosynthesis thus, enhancing S. molle’s performance through the hotter and drier climate in California.

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