title: Key sources and seasonal dynamics of greenhouse gas fluxes from yak grazing systems on the Qinghai-Tibetan Plateau.
abstract: Greenhouse gas (GHG) emissions from livestock grazing systems are contributing to global warming. To examine the influence of yak grazing systems on GHG fluxes and relationships between GHG fluxes and environmental factors, we measured carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes over three key seasons in 2012 and 2013 from a range of potential sources, including: alpine meadows, dung patches, manure heaps and yak night pens, on the Qinghai-Tibetan Plateau. We also estimated the total annual global warming potential (GWP, CO2-equivalents) from family farm grazing yaks using our measured results and other published data. In this study, GHG fluxes per unit area from night pens and composting manure heaps were higher than from dung patches and alpine meadows. Increased moisture content and surface temperature of soil and manure were major factors increasing CO2and CH4fluxes. High contributions of CH4and N2O (21.1% and 44.8%, respectively) to the annual total GWP budget (334.2 tonnes) strongly suggest these GHG other than CO2should not be ignored when estimating GWP from the family farm grazing yaks on the Qinghai-Tibetan Plateau for the purposes of determining national and regional land use policies or compiling global GHG inventories.
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Caiyu
authors.initials: C
authors.lastname: Yan
authors.affiliation: Institute of Agriculture and Environment, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
authors.forename: Cory
authors.initials: C
authors.lastname: Matthew
authors.affiliation: Institute of Agriculture and Environment, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
authors.forename: Brennon
authors.initials: B
authors.lastname: Wood
authors.affiliation: State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.
authors.forename: Fujiang
authors.initials: F
authors.lastname: Hou