Water availability and plant diversity

As water availability declines in California’s plant communities, biodiversity also declines, according to a study. In addition to the effect of rising temperatures on cold ecosystems, climate change is expected to reduce water availability in water-limited ecosystems, such as those found in California, where precipitation generally falls only in the winter months. To predict how and why plant diversity varies with climate in water-limited regions, Susan Harrison and colleagues reviewed previous studies and performed fresh analyses of plant diversity in California, focusing on plants growing in serpentine soils, which are chemically harsh and nutrient-poor. The authors collected data from 224 field plots at 78 sites in 54 regions spanning coniferous forests, deciduous forests, chaparral, and open grasslands. The regions received 200-1,800 mm of water annually. The authors found that taxonomic diversity, as well as functional diversity, or variation in trait types, were greater in areas of relatively high water availability. Comparing results across time, the authors found that during a prolonged drying period in Northern California, species diversity, functional diversity, and the diversity of evolutionary lineages represented declined. According to the authors, the results indicate that the multi-level loss of plant community diversity in water-limited areas might be predictable.

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Article #19-21724: ” Climate and plant community diversity in space and time,” by Susan Harrison, Marko Spasojevic, and Daijiang Li.

MEDIA CONTACT: Susan Harrison, University of California, Davis, CA; tel: 530-902-1686; e-mail: <

[email protected]

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