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Abstract Detail


Smith, Karagan [1], Davis, Stephen [1].

Mechanisms by which Exotic Schinus molle has greater drought tolerance than native Malosma laurina.

Between 2012-2016 Southern California experienced a historic drought, that negatively affected much of the chaparral vegetation in the Santa Monica Mountains. An invasive species in chaparral shrub communities, Schinus molle, was notably better at conserving water than native chaparral species such as Malosma laurina. In the spring of 2017, California experienced improved seasonal rainfall. Knowing that Schinus molle was able to outperform Malosma laurina during times of drought, we were interested in discerning if this pattern persisted during times of plentiful moisture. We compared the water potential and photosynthetic performance of Schinus molle to Malosma laurina in the dry summer of 2016 and again during the wet summer of 2017. We used a Scholander-Hammel pressure chamber to measure water potential and a Li-6400XT gas-exchange system to measure photosynthetic performance. We hypothesized that due to the increase in rainfall during summer 2017, water potential and photosynthetic performance of the invasive Schinus molle and Malosma laurina would both increase post-drought. We also hypothesized that the water potential and photosynthetic performance of Schinus molle would remain greater than that of native Malosma laurina. We found that both species had significant recovery in photosynthesis, pre-dawn water potential, and stomatal conductance. We also observed that Schinus molle had a higher photosynthetic rate (17 μmol m-2 s-1) than that of Malosma laurina (12 μmol m-2 s-1) whereas in 2016 there was no significant difference between the two (both about 3μmol m-2 s-1). Another discovery was that the stomatal conductance of Schinus molle in summer 2016 was very low (0.2 mmol m-2 s-1) but during the summer or 2017 increased to 160 mmol m-2 s-1. Taken together, our results indicate that the invasive ability of Schinus molle into chaparral shrub communities is facilitated by its exceptional ability to conserve water during drought and recover high photosynthetic rates during times of favorable moisture. Furthermore, our results suggest significant post-drought recovery for both invasive and native species between 2016 and 2017, with enhanced invasive ability of Schinus molle.

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1 - Pepperdine University, NATURAL SCIENCE DIV, 24255 Pacific Coast Highway, Malibu, CA, 90263, United States

Invasive species

Presentation Type: Poster
Session: P, Physiology Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPS005
Abstract ID:847
Candidate for Awards:None

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