Photosynthetic strategies of two Mojave Desert shrubs

Authors

G. E. Kleinkopf, Laboratory of Nuclear Medicine and Radiation Biology, University of California, Los Angeles, California 90024
T. L. Hartsock, Laboratory of Nuclear Medicine and Radiation Biology, University of California, Los Angeles, California 90024
A. Wallace, Laboratory of Nuclear Medicine and Radiation Biology, University of California, Los Angeles, California 90024
E. M. Romney, Laboratory of Nuclear Medicine and Radiation Biology, University of California, Los Angeles, California 90024

Abstract

Photosynthetic production of two Mojave Desert shrubs was measured under natural growing conditions at UCLA. Measurements of photosynthesis, transpiration, resistances to water vapor flux, soil moisture potential, and tissue water potential were made. Atriplex canescens (Pursh) Nutt., a member of the C₄ biochemical carbon dioxide fixation group was highly competitive in growth rate and production during conditions of adequate soil moisture. As soil moisture conditions declined to minus 40 bars, the net photosynthetic rate of Atriplex decreased to zero. However, the C₃ shrub species Larrea tridentata (Sesse & Moc. ex DC.) Gov. was able to maintain positive net photosynthetic production during conditions of high temperature and extreme low soil moisture through the major part of the season. The comparative advantages of the C₄ versus the C₃ pathway of carbon fixation was lost between these two species as the soil moisture potential declined to minus 40 bars. Desert plants have different strategies for survival, one of the strategies being the C₄ biochemical carbon fixation pathway. However, many of the plants are members of the G₃ group. In this instance, the C₄ fixation pathway does not confer an added advantage to the productivity of the species in the Mojave Desert. Species distribution based on comparative photosynthetic production is discussed.

Recommended Citation

Kleinkopf, G. E.; Hartsock, T. L.; Wallace, A.; and Romney, E. M. (1980) "Photosynthetic strategies of two Mojave Desert shrubs," Great Basin Naturalist Memoirs: Vol. 4, Article 14.
Available at: https://scholarsarchive.byu.edu/gbnm/vol4/iss1/14