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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #316045
Title: Methane uptake by four land-use types in the agro-pastoral region of northern China

Author
item RONG, YUPING - China Agricultural University
item MA, LEI - China Agricultural University
item Johnson, Douglas

Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2015
Publication Date: 6/9/2015
Citation: Rong, Y., Ma, L., Johnson, D.A. 2015. Methane uptake by four land-use types in the agro-pastoral region of northern China. Atmospheric Environment. 116:12-21.

Interpretive Summary: Land-use types and management practices of the agro-pastoral region of northern China may affect the exchange of methane (a potent greenhouse gas). In addition, most previous studies with methane fluxes have been conducted primarily during the growing season, not for the entire year. Our study investigated annual methane fluxes from four land-use types (ungrazed grassland, moderately grazed grassland, perennial pasture and cropland), which are the dominant land-use types in northern China. Fluxes of methane were measured throughout the year with a mobile gas analyzer. Results showed that soils were a sink for atmospheric methane throughout the year for all land-use types. Methane uptake during the non-growing season represented about 50% of annual uptake for the grassland land-use types and 21% for the cropland and perennial pasture land-use types. Moderate grazing by sheep increased annual methane uptake by 78% compared to ungrazed grassland. These results contribute to our understanding of methane uptake in major land-use types of northern China.

Technical Abstract: Land-use types and management practices of temperate semiarid steppes may affect soil sink activity for atmospheric methane (CH4). Most prevous studies related to CH4 have focused primarily on the growing season with only a few studies evaluating CH4 fluxes throughout the entire year. With CH4 exchange largely undocumented during the non-growing season, the annual CH4 uptake in different land-use types under various management practices is uncertain. The aim of this study was to investigate the annual variation of CH4 fluxes from four land-use types (ungrazed grassland, moderatly grazed grassland, perennial pasture and cropland), which are the dominant land-use types in the agro-pastoral region of northern China. Fluxes of CH4 were measured throughout the year in four land-use types using a mobile greenhouse gas analyzer. Results showed that soils were a sink for atmospheric CH4 throughout the year for all land-use types. Annual CH4 uptake patterns were associated with specific land-use types, whereas seasonality of CH4 uptake was related to monthly mean temperature and precipitation. Monthly mean temperature and precipitation explained 56% of the variability in monthly cumulative soil CH4 uptake. Annual CH4 uptake across all land-use types averaged 3.9 plus or minus 0.17 kg C ha-1 yr-1. CH4 uptake during the non-growing season represented about 50% of annual CH4 uptake for the grassland types and 21% for the cropland and perennial pasture land-use types. Moderate grazing (stocking rate 1.43 sheep ha-1 yr-1), significantly increased annual CH4 uptake by 78% (P<0.05) compared to ungrazed grassland. The highest annual CH4 uptake was observed for cropland (10.2 kg C ha-1 yr-1), followed by 2.7 kg C ha-1 yr-1 for perennial pasture. No pulses of soil CH4 fluxes were observed during the freeze-thaw period in spring and autumn. Our results documented year-long CH4 fluxes in four important land-use types in the expansive agro-pastoral region of northern China and contribute to our understanding of soil uptake levels of atmospheric CH4.