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Long‐Term Grazing Alters Soil Trace Gas Fluxes from Grasslands in the Foothills of the Rocky Mountains, Canada
Author(s) -
Gao Xinlei,
Thomas Ben W.,
Beck Ryan,
Thompson Don J.,
Zhao Mengli,
Willms Walter D.,
Hao Xiying
Publication year - 2018
Publication title -
land degradation and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.403
H-Index - 81
eISSN - 1099-145X
pISSN - 1085-3278
DOI - 10.1002/ldr.2664
Subject(s) - grazing , grassland , environmental science , soil water , agronomy , growing season , soil science , biology
Long‐term cattle grazing may degrade grassland soils, but how soil CO 2 , CH 4 and N 2 O fluxes respond to long‐term cattle grazing is poorly understood. Therefore, we quantified soil CO 2 , CH 4 and N 2 O fluxes in response to four levels (none, light, heavy, very heavy) of long‐term (>65 years) cattle grazing on a rough fescue grassland in the foothills of the Rocky Mountains, Canada over three grazing seasons. The grazed grassland soils emitted 37 to 51% more CO 2 than non‐grazed soils. Grazed grassland soils were small CH 4 sinks and small N 2 O sources each season, and their cumulative fluxes were significantly affected by a cattle stocking rate × year interaction, indicating the grazing effect was influenced by environmental conditions. Soil CH 4 uptake was negatively correlated with soil moisture ( r = −0·59). The 2013 grazing season had about 41% greater precipitation than average and grazing significantly decreased CH 4 uptake 31 to 38% compared with non‐grazed soils. The N 2 O emissions were 122 to 179% greater with heavy and very heavy grazing than none in the wet season, unaffected by grazing in the normal precipitation season and 72% lower with light grazing than none in the dry season. Predicting trace gas fluxes from grazed grassland soils across space and time is difficult because of interactions among weather conditions, edaphic properties and grazing intensity. However, long‐term cattle grazing increased soil CO 2 fluxes, while the grazing effect on CH 4 uptake depended on precipitation and the soil N 2 O flux responded as a function of grazing intensity and precipitation. © 2016 Her Majesty the Queen in Right of Canada. Land Degradation & Development Published by John Wiley & Sons Ltd.