Predictions regarding future climate change vary greatly among regions,
and these predictions include directional changes such as more arid
conditions in the US Southwest (Seager et al. 2007), as well as an
expectation of greater interannual variability (Easterling et al. 2000).
Ecologists are charged with identifying biotic communities and
ecosystems most at risk for declines in diversity and functioning, which
first requires an understanding of how diversity and ecosystem function
respond to current temporal and spatial variation in climate, including
interannual climate variation. In many systems there is great
interannual variation in climate, making long-term observations of
species composition and ecosystem functioning essential for documenting
these climate-composition-function relationships.