Increases in thermophilus plants in an arid alpine community in response to experimental warming

Abstract

A warming climate has been shown to drive thermophilization—shifts in species abundance toward those adapted to warm and dry conditions. The community dynamics shaping this process have been proposed to vary between temperature-limited alpine plant communities and those that are both temperature and moisture limited. In nine sites across the xeric alpine zone in the White Mountains, California, USA, we experimentally increased summertime temperature and precipitation for three seasons and quantified community responses with a climatic niche analysis. We asked if thermophilization occurred in response to experimental heating, and if this effect was ameliorated by experimental watering. Under experimentally warmer conditions, we found no change in the mean community-weighted climatic niche (CCN); however, thermophilization of this community was observed based on a shift in the seventy-fifth percentile of the CCN and an increase in the proportional abundance of the hottest, driest adapted species. In addition, total vegetation abundance increased and species richness decreased with heating. Experimental watering did not ameliorate these effects of heating. Together, these results suggest that warming in arid alpine areas may result in less diverse plant communities dominated by hot, dry associated species, although short-term responses may be limited because of community lags.

Keywords

• alpine
• arid
• climate change
• community climatic niche
• thermophilization