Tree rings detect earthworm invasions and their effects in northern Hardwood forests

TitleTree rings detect earthworm invasions and their effects in northern Hardwood forests
Publication TypeJournal Article
Year of Publication2010
AuthorsLarson, Evan R., Kipfmueller Kurt F., Hale Cindy M., Frelich Lee E., and Reich Peter B.
JournalBiological Invasions
Volume12
Pagination1053 - 1066
Date Published5/2010
KeywordsAcer saccharum, Climate-tree growth relationship, dendroecology, Earthworm invasion, European earthworms, Northern Minnesota
Abstract

Invasions of European earthworms into the forests of northern North America are causing dramatic changes in forest floor structure, vegetation communities, biogeochemical cycling, and site hydrology. However, long-term studies on the effects of invasive earthworms are limited because little data exist on the timing and rate of earthworm invasion at specific sites. We successfully used tree rings to identify the timing of earthworm invasions and the effects of earthworm activity on the Acer saccharum overstory of two recently invaded sites in northern Minnesota, thereby establishing a method to date earthworm invasions at other sites. In addition to identifying a tree-ring signature related to earthworm invasion, we found trees growing in invaded conditions were more sensitive to drought than trees growing in earthworm-free conditions. Increased drought sensitivity by A. saccharum has important implications for possible range shifts under climate change scenarios that include increasing drought frequency and severity.