The number of plant species in a California grassland area has dropped since 2000 as the area has become more arid — an indication of how such ecosystems might respond to climate change.
Susan Harrison and her colleagues at the University of California, Davis, monitored plant diversity at 80 sites across a 27-square-kilometre area from 2000 to 2014. They found that the number of species at the sites and across the study area decreased over time, particularly in the number of native annual flowering plants. The decline in diversity correlated with diminishing precipitation during winter, when the annual plants are seedlings. The team did not find links between the fall in diversity and other possible causes such as fire, invasive species or nitrogen levels.
A reduction in precipitation is predicted for this area as the climate warms, so such biodiversity losses could signify future extinctions.
Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1502074112 (2015)