Land use history determines non-native earthworm impacts on atmospheric methane consumption in forest soils, central New York State

Yavitt, J. B. 2015. Land use history determines non-native earthworm impacts on atmospheric methane consumption in forest soils, central New York State. Can. J. Soil Sci. 95: 321–330. I used complementary field and laboratory studies to examine the impact of two types of soil disturbance on net consumption of atmospheric methane (CH4) in forest soils near Ithaca, New York. One type of disturbance is invasion of non-native earthworms that mix soil layers, and the other is agriculture, which reduces the pit-and-mound surface topography to a flat landscape. Measurements of CH4 fluxes between soil and the atmosphere were made in autumn before seasonal leaf fall when earthworms had consumed all of the previous year's leaf fall, and revealed no impact by earthworms in the never-tilled soils. Although earthworms did lead to greater consumption of atmospheric CH4 in the post-agriculture soils, the mean consumption rate was only −0.2 mg m2 d−1. Concentrations of atmospheric CH4 in wormed soils were often greater than that in the atmosphere, suggesting that earthworms promote CH4 production. In general, earthworms decreased soil permeability to gas diffusion. Post-agriculture soils also had faster CH4 oxidation rates when incubated in the laboratory. The results taken together suggest that earthworm impacts on atmospheric CH4 consumption depend on the history of soil disturbance.