title: Methane emissions from the trunks of living trees on upland soils.
abstract: Upland forests are traditionally thought to be net sinks for atmospheric methane (CH4 ). In such forests, in situ CH4 fluxes on tree trunks have been neglected relative to soil and canopy fluxes. We measured in situ CH4 fluxes from the trunks of living trees and other surfaces, such as twigs and soils, using a static closed-chamber method, and estimated the CH4 budget in a temperate upland forest in Beijing. We found that the trunks of Populus davidiana emitted large quantities of CH4 during July 2014-July 2015, amounting to mean annual emissions of 85.3 and 103.1 μg m(-2)  h(-1) on a trunk surface area basis on two replicate plots. The emission rates were similar in magnitude to those from tree trunks in wetland forests. The emitted CH4 was derived from the heartwood of trunks. On a plot or ecosystem scale, trunk CH4 emissions were equivalent to c. 30-90% of the amount of CH4 consumed by soils throughout the year, with an annual average of 63%. Our findings suggest that wet heartwoods, regardless of rot or not, occur widely in living trees on various habitats, where CH4 can be produced.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.|State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110164, China.
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.|University of Chinese Academy of Sciences, Yuquanlu, Beijing, 100049, China.
authors.forename: Feng-Dan
authors.initials: FD
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Huang
authors.affiliation: Smithsonian Environmental Research Center, PO Box 28, Edgewater, MD, 21037-0028, USA.
authors.forename: J Patrick
authors.initials: JP
authors.lastname: Megonigal
authors.affiliation: State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110164, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110164, China.
authors.forename: Xiao-Tao
authors.initials: XT
authors.lastname: Lü
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.
authors.forename: Ling-Hao
authors.initials: LH
authors.lastname: Li
authors.affiliation: Department of Renewable Resources, University of Alberta, Edmonton, T6G 2E3, Alberta, Canada.
authors.forename: Scott
authors.initials: S
authors.lastname: Chang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.
authors.forename: Yun-Hai
authors.initials: YH
authors.lastname: Zhang
authors.affiliation: Institute of Desertification Studies, Chinese Academy of Forestry, Beijing, 100091, China.
authors.forename: Jin-Chao
authors.initials: JC
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing, 100093, China.|State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110164, China.
authors.forename: Xing-Guo
authors.initials: XG
authors.lastname: Han
mesh_terms: D017753:Ecosystem; D008697:Methane / Q000032:analysis*; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry*; D013997:Time Factors; D014197:Trees / Q000737:chemistry*; D014934:Wood / Q000737:chemistry
chemical_list: D012987:Soil; D008697:Methane
keywords: annual variability; drained soils; heartwood; in situ methane (CH4) flux; poplar (Populus davidiana); temperate forest