Climate-driven biodiversity loss

Changes in biodiversity have been reported globally to go both up and down in various ecological communities, but so far only a few of these changes have been linked to climate change. Now, Susan Harrison and co-workers from University of California, Davis have monitored plant diversity on a 27 km2 semiarid California grassland over 15 years. They found several signs of loss of biodiversity to correlate with decreased midwinter precipitation, while other possible causes such as livestock grazing, fire, nitrogen deposition, and invasive species could be ruled out. The number of plant species declined over the period both at local sites and within the whole area, and native annual wildflowers were most affected. The mean specific leaf area (SLA) declined in this group of plants, and since high SLA is an indicator of low drought tolerance, this suggests that drought-intolerant plants were specifically lost. That explanation was supported by the observation, that biodiversity loss was most pronounced on fertile, non-serpentine soils. Since many semiarid regions are expected to become increasingly dry due to climate change in the near future, the authors believe that this may foreshadow extensive biodiversity loss, larger-scale extinctions and lower productivity.

Source: Harrison et al (22 June 2015) PNAS doi:10.1073/pnas.1502074112