Is increased precipitation during the 20th century statistically or ecologically significant in the eastern US?

摘要

We address the climate versus disturbance debate to understand drivers of change in human-environment systems. We examine whether recent increased precipitation episodes ('pluvials') are unique and have ecological implications for the humid climate of the eastern United States. Robust statistical analyzes presented here indicate that the 20th century was wet, but not significantly different than other centuries during the last millennium. Statistical methods did not establish increased precipitation episodes as an unusual change that correlated with transition shifts in eastern forests during the early 20th century. Additionally, modest precipitation change was not ecologically significant enough to result in forests composed of drought-tolerant trees in the past or drought-intolerant trees currently. We conclude that fire is a parsimonious explanation for composition and structure of historical open fire-tolerant oak and pine forests. Fire exclusion was unprecedented during early 20th century and loss of this driver provides a mechanism for forest transitions.