Presentation Title

Post-Drought Recovery in the Chaparral Shrub Ceanothus Spinosus

Faculty Mentor

Stephen D. Davis

Start Date

17-11-2018 8:30 AM

End Date

17-11-2018 10:30 AM

Location

CREVELING 86

Session

POSTER 1

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

This study investigated the abilities of Ceanothus spinosus, or greenbark ceanothus, to recover after a historic drought. This plant is one of the hardiest in the Santa Monica Mountains, providing soil stabilization and nutrients to other organisms in the ecosystem. In a previous investigation done during the drought, it was found that C. spinosus subjects growing in their natural habitat experienced significant dieback, with predawn water potentials falling as low as -7 MPa and native embolisms at an average of 47.17% (Ross et al., 2016). Other parameters tested were stomatal conductance, photosynthetic rate, and chlorophyll fluorescence. Compared to the values found for C. spinosus subjects unaffected by the drought, the health of naturally occurring C. spinosus was significantly worse. To see if the health of C. spinosus had improved since the drought, this previous investigation was repeated. Fortunately, this study found that C. spinosus subjects affected by drought made a notable recovery just eight months after the drought ended. Water potentials improved significantly, with the highest recorded being at -1.75 MPa, and embolisms decreased by half since last year, with an average of 23.1% (P = 0.05). Values for photosynthetic rate (1.39 μmolm-2 s1 increase from last year), and chlorophyll fluorescence (0.09 increase from last year) showed improvement in the plant’s health as well. California is likely to experience severe droughts in the future, so it is promising that C. spinosus can make an effective recovery from this environmental stressor.

Summary of research results to be presented

Dry Ceanothus spinosus in 2017 showed overall improvement in health compared to its condition in 2016 with a lowered water potential (x̅=-6.59 MPa in 2016 to x̅ = -2.32 MPa in 2017), an increased fluorescence rate (x̅ = 0.73 in 2016 to x̅=0.82 in 2017), an increased photosynthetic rate (x̅=-0.21 μmol/m-2 s-1) in 2016 to x̅ = 1.18 μmol m-2 s-1 in 2017), and a lowered percentage of air embolism in the xylem (x̅=47.17% in 2016 to x̅=23.1%in 2017).

Irrigated (control) C. spinosus, stayed consistent with 2016 data with no change in the fluorescence and percentage of air embolism in the xylem. There was a slight increase in water potential(x̅=-3.4 MPa in 2016 to x̅=-1.34 MPa in 2017) and the photosynthetic rate (x̅=9.02 μmol m-2 s-1 in 2016 to 11.1 μmol m-2 s-1 in 2017).

The drought induced dieback of C. spinosus showed a significant change in water potential, gas exchange, fluorescence, and water flow rate. Since the drought, C.spinosus is showing signs of improvement in its health.

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Nov 17th, 8:30 AM Nov 17th, 10:30 AM

Post-Drought Recovery in the Chaparral Shrub Ceanothus Spinosus

CREVELING 86

This study investigated the abilities of Ceanothus spinosus, or greenbark ceanothus, to recover after a historic drought. This plant is one of the hardiest in the Santa Monica Mountains, providing soil stabilization and nutrients to other organisms in the ecosystem. In a previous investigation done during the drought, it was found that C. spinosus subjects growing in their natural habitat experienced significant dieback, with predawn water potentials falling as low as -7 MPa and native embolisms at an average of 47.17% (Ross et al., 2016). Other parameters tested were stomatal conductance, photosynthetic rate, and chlorophyll fluorescence. Compared to the values found for C. spinosus subjects unaffected by the drought, the health of naturally occurring C. spinosus was significantly worse. To see if the health of C. spinosus had improved since the drought, this previous investigation was repeated. Fortunately, this study found that C. spinosus subjects affected by drought made a notable recovery just eight months after the drought ended. Water potentials improved significantly, with the highest recorded being at -1.75 MPa, and embolisms decreased by half since last year, with an average of 23.1% (P = 0.05). Values for photosynthetic rate (1.39 μmolm-2 s1 increase from last year), and chlorophyll fluorescence (0.09 increase from last year) showed improvement in the plant’s health as well. California is likely to experience severe droughts in the future, so it is promising that C. spinosus can make an effective recovery from this environmental stressor.