Critical land change information enhances the understanding of carbon balance in the United States Academic Article uri icon

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abstract

  • Large-scale terrestrial carbon (C) estimating studies using methods such as atmospheric inversion, biogeochemical modeling, and field inventories have produced different results. The goal of this study was to integrate fine-scale processes including land use and land cover change into a large-scale ecosystem framework. We analyzed the terrestrial C budget of the conterminous United States from 1971 to 2015 at 1-km resolution using an enhanced dynamic global vegetation model and comprehensive land cover change data. Effects of atmospheric CO2 fertilization, nitrogen deposition, climate, wildland fire, harvest, and land use/land cover change (LUCC) were considered. We estimate annual C losses from cropland harvest, forest clearcut and thinning, fire, and LUCC were 436.8, 117.9, 10.5, and 10.4 TgC/year, respectively. C stored in ecosystems increased from 119,494 to 127,157 TgC between 1971 and 2015, indicating a mean annual net C sink of 170.3 TgC/year. Although ecosystem net primary production increased by approximately 12.3 TgC/year, most of it was offset by increased C loss from harvest and natural disturbance and increased ecosystem respiration related to forest aging. As a result, the strength of the overall ecosystem C sink did not increase over time. Our modeled results indicate the conterminous US C sink was about 30% smaller than previous modeling studies, but converged more closely with inventory data.

authors

  • Liu, Jinxun
  • Sleeter, Benjamin M
  • Zhu, Zhiliang
  • Loveland, Thomas R
  • Sohl, Terry
  • Howard, Stephen M
  • Key, Carl H
  • Hawbaker, Todd
  • Liu, Shuguang
  • Reed, Bradley
  • Cochrane, Mark A
  • Heath, Linda S
  • Jiang, Hong
  • Price, David T
  • Chen, Jing
  • Zhou, Decheng
  • Bliss, Norman B
  • Wilson, Tamara
  • Sherba, Jason
  • Zhu, Qiuan
  • Luo, Yiqi
  • Poulter, Benjamin

publication date

  • July 2020