Long term study of shifts in ant community composition over a naturally occuring climate gradient and experimental heating manipulation

Background/Question/Methods

We studied the effects of climate change on ant community composition using a combination of a naturally occurring climate gradient and an experimental heating manipulation conducted at the Rocky Mountain Biological Station in Gothic Colorado. The climate gradient is created by three subalpine meadow sites spread over a 500m elevation gradient, which brackets the fourth heating manipulation at a subalpine meadow site. The fourth site occurring at a mid-elevation in the 500m range has undergone an experimental heating manipulation by overhead electric radiant heaters since 1991. The natural climate gradient created over the 500m elevation range is equivalent to the gradient created in the experimental site of a roughly 10-20 day shift in snowmelt date and 1⁰C difference in soil temperature. We compared ant community data collected at all four sites in 1998 to collections made at the same sites in 2010. 

Results/Conclusions

From 1998 to 2010 there was a community wide shift in ant composition along the natural climate gradient. We found that ant communities at higher elevation sites came to resemble ant communities previously found at low elevation sites. Conversely, after 19 years of experimental warming, there was little discernible effect on the composition of ant communities, but there was a slight increase in overall ant abundance. A key unresolved question we are now exploring is what features the species of low elevation communities share and what might drive such change even when strong experimental warming appeared to have very little effect.