Abstract Detail


Ongjoco, Anna Jiselle [1], Bobich, Edward [2], Ewers, Frank [3], Questad, Erin [2].

Strategies Utilized by Pinus coulteri and Pinus attenuata for Surviving at Low Elevations in the San Bernardino Mountains .

Pinus attenuata(knobcone pine) and Pinus coulteri(coulter pine) are the two most common pines in the lower elevations of the San Bernardino Mountains of California. The goal of this study was to determine how these species survive at such low elevations and respond to extreme drought, like that of 2011-2016, which was the most severe on record. Physiological, morphological, and anatomical measurements were used to compare the responses of these two species to seasonal environmental changes and induced drought. Based on a previous study, it was hypothesized that P. attenuata would have an isohydric response to drought and P. coulteri would have an anisohydric response to drought in both natural and controlled conditions. Overall, P. coulteri had greater water potentials and maximum quantum yield of photosystem II (FV/FM) than P. attenuata, but had similar stomatal conductance and gas exchange in the field. In a controlled drought study, young P. coulteri displayed lower water potentials than young P. attenuata, but higher gas exchange and stomatal conductance, indicating that P. coulteri utilizes an anisohydric response to drought. Both species had similar FV/FM. Tracheid diameter was larger for P. attenuata than P. coulteri, and P. coulteri had thicker cell walls, indicating that more reinforcement is needed to prevent cavitation when P. coulteri is taking up COat low water potentials. Finally, P. attenuata and P. coulteri did not differ in height, but did differ in diameter at breast height, with P. coulteri being wider. Thus, P. attenuata’s higher zero carbon assimilation point in the greenhouse and lower water potentials in the field indicates why it has historically experienced higher mortality than P. coulteri.

1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 W. Temple Avenue, Pomona, CA, 91768, United States
2 - California State Polytechnic University, Pomona, Biological Sciences, 3801 West Temple Avenue, Pomona, CA, 91768, USA
3 - California State Polytechnic University, Pomona, Department Of Biology, 3801 West Temple Avenue, Pomona, CA, 91768, United States


Presentation Type: Oral Paper
Session: ECOPH1, Ecophysiology I
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 11:30 AM
Number: ECOPH1003
Abstract ID:307
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation

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