title: MODIS Based Estimation of Forest Aboveground Biomass in China.
abstract: Accurate estimation of forest biomass C stock is essential to understand carbon cycles. However, current estimates of Chinese forest biomass are mostly based on inventory-based timber volumes and empirical conversion factors at the provincial scale, which could introduce large uncertainties in forest biomass estimation. Here we provide a data-driven estimate of Chinese forest aboveground biomass from 2001 to 2013 at a spatial resolution of 1 km by integrating a recently reviewed plot-level ground-measured forest aboveground biomass database with geospatial information from 1-km Moderate-Resolution Imaging Spectroradiometer (MODIS) dataset in a machine learning algorithm (the model tree ensemble, MTE). We show that Chinese forest aboveground biomass is 8.56 Pg C, which is mainly contributed by evergreen needle-leaf forests and deciduous broadleaf forests. The mean forest aboveground biomass density is 56.1 Mg C ha-1, with high values observed in temperate humid regions. The responses of forest aboveground biomass density to mean annual temperature are closely tied to water conditions; that is, negative responses dominate regions with mean annual precipitation less than 1300 mm y-1 and positive responses prevail in regions with mean annual precipitation higher than 2800 mm y-1. During the 2000s, the forests in China sequestered C by 61.9 Tg C y-1, and this C sink is mainly distributed in north China and may be attributed to warming climate, rising CO2 concentration, N deposition, and growth of young forests.
authors.affiliation: College of Urban and Environmental Sciences, Peking University, Beijing, China.
authors.forename: Guodong
authors.initials: G
authors.lastname: Yin
authors.affiliation: College of Urban and Environmental Sciences, Peking University, Beijing, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Urban and Environmental Sciences, Peking University, Beijing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: College of Urban and Environmental Sciences, Peking University, Beijing, China.
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: College of Urban and Environmental Sciences, Peking University, Beijing, China; Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shilong
authors.initials: S
authors.lastname: Piao
mesh_terms: D018533:Biomass; D002681:China; D002980:Climate; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D065928:Forests; D005843:Geography; D062206:Spatial Analysis; D014197:Trees