Land use change converts temperate dryland landscape into a net methane source
Vengrai, U., K. M. Tucker and W. K. Lauenroth. 2025.
Abstract
Drylands cover approximately 40% of the global land surface and are thought to
contribute significantly to the soil methane sink. However, large-scale methane
budgets have not fully considered the influence of agricultural land use change in
drylands, which often includes irrigation to create land cover types that support
hay or grains for livestock production. These land cover types may represent a
small proportion of the landscape but could disproportionately contribute to
land-atmosphere methane exchange and are currently omitted in estimates of
dryland methane fluxes. We measured methane fluxes among big sagebrush,
introduced wetlands, and hay meadows in a semiarid temperate dryland in
Wyoming, USA, to investigate how these small-scale irrigated land cover types
contributed to landscape-scale methane dynamics over the summer of 2021. Big
sagebrush ecosystems dominated the landscape, while the introduced wetlands
and hay meadows represented approximately 1% and 12%, respectively. Methane
uptake was consistent in the big sagebrush ecosystems, emissions and uptake
were variable in the hay meadows, and emissions were consistent in the intro-
duced wetlands. Despite making up 1% of the total land area, methane production
in the introduced wetlands overwhelmed consumption occurring throughout the
rest of the landscape, making this region a net methane source. Our work sug-
gests that introduced wetlands and other irrigated land cover types created for
livestock production may represent a significant, previously overlooked source of
anthropogenic methane in this region and perhaps in drylands globally.
Key Words
big sagebrush, greenhouse gas, introduced wetland, land use change
