Authors: Mac A. Callaham; Bruce A. Snyder; Joseph J. O'BrienEarthworms are frequently referred to as ecosystem engineers due to their profound modification of soil physical and chemical characteristics through their feeding, burrowing and casting activity. The impacts of earthworms on soil ecosystems can be particularly pronounced when non-native species are introduced, and our previous work has documented the impacts of one introduced Asian species, Amynthas agrestis, on forest floor depth, diversity and abundance of other native detritivores, and soil food-web interactions. In light of hypothesized relationships between forest floor (duff) consumption and post-fire overstory mortality, we propose here a conceptual model describing expected ecosystem responses to wildfire under four different vegetation and earthworm invasion scenarios (oak-hickory vs. maple-poplar and invaded vs. uninvaded). Our model predicts decreased duff accumulation with earthworm invasion, and near total absence of duff in invaded maple/poplar stands. The decreased duff accumulation predicted in earthworm-invaded oak/hickory stands may confer a post-fire advantage to these trees as they would be expected to lose less fine root biomass in fires due to duff consumption. Invasive earthworm impacts on forest floor accumulation and upper mineral soil horizon characteristics may also have important implications for net carbon loss in fire events, and these considerations will also be addressed.
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