Pedosphere 31(3): 413--422, 2021
ISSN 1002-0160/CN 32-1315/P
©2021 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Earthworm functional groups are related to denitrifier activity in riparian soils
Chen CHEN1, Leanne EJACK2, Martin R. CHÉNIER3, Joann K. WHALEN1
1State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Guangzhou 510535 (China)
2Department of Natural Resource Sciences, Macdonald Campus, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec H9X 3V9 (Canada)
3Department of Food Science and Agricultural Chemistry and Department of Animal Science, Macdonald Campus, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec H9X 3V9 (Canada)
ABSTRACT
      Riparian buffers, located in the transition zone between terrestrial and aquatic ecosystems, are a hotspot for nitrogen (N) removal through denitrification. Earthworms are abundant in riparian buffers and may enhance denitrification. This study investigated earthworm demographics of three earthworm functional groups (anecic, epigeic, and endogeic) and denitrifier activity in temporarily flooded and non-flooded riparian soils from April to October 2012 in southern Quebec, Canada. Nine earthworm species, mostly endogeic, were found in the temporarily flooded soil, while only six earthworm species were found in the non-flooded soil. On average, there were 11.7 times more earthworms with 12.4 times greater biomass (P<0.05) found in the temporarily flooded soil than in the non-flooded soil. The denitrification enzyme activity (DEA) was of similar magnitude in temporarily flooded and non-flooded soils, with temporal variation associated with rainfall patterns. Endogeic earthworm biomass was positively correlated (P<0.05) with DEA, while epigeic earthworm biomass was positively correlated (P<0.05) with 16S rRNA gene copies and nosZ gene copies from bacteria, indicating an association between earthworm functional groups and denitrifier activity in riparian soils. Stepwise multiple regressions showed that DEA in riparian soils could be predicted using soil moisture, inorganic N concentration, and earthworm functional groups, suggesting that endogeic and epigeic earthworms contributed to denitrifier activity in riparian soils.
Key Words:  endogeic earthworms,epigeic earthworms,riparian areas,riparian buffer,macrofauna,seasonal change,denitrification enzyme activity,denitrifier gene copy
Citation: Chen C, Ejack L, Chénier M R, Whalen J K. 2021. Earthworm functional groups are related to denitrifier activity in riparian soils. Pedosphere. 31(3): 413-422.
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