Critical land change information enhances the understanding of carbon balance in the United States. (14th April 2020)

• Record Type: Journal Article
• 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 M.; Zhou, Decheng; Bliss, Norman B.; Wilson, Tamara; Sherba, Jason; Zhu, Qiuan; Luo, Yiqi; Poulter, Benjamin
• Is Part Of: Global change biology. Volume 26:Number 7(2020)
• Page Start: 3920
• Page End: 3929
• Publication Date: 2020-04-14
• Subjects: carbon sequestration -- DGVM -- ecosystem model -- ecosystem productivity -- land use and land cover change -- wildfire; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.15079
• Languages: English
• ISSNs: 1354-1013

Abstract

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. Abstract : Carbon (C) sequestration estimates from bottom‐up ecosystem models are usually smaller than estimates from atmospheric inversion models and larger than field inventory results. Here, we quantify C dynamics of the conterminous United States at 1‐km spatial resolution focusing on detailed land cover changes over recent decades, using several proven and established national data products. Our research highlights that the combined impacts of land management, human‐dependent land use change, and natural disturbance on C are greater than those associated with climate variability, and that process modeling can converge with field inventory data when detailed land cover change information is used.