Contrasting Responses of Soil Inorganic Carbon to Afforestation in Acidic Versus Alkaline Soils

Journal Article · 25 December 2021 · Global Biogeochemical Cycles

DOI: https://doi.org/10.1029/2021gb007038 · OSTI ID:1978510

Hong, Songbai  ^[1]; Chen, Anping  ^[2]

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1. Peking Univ., Beijing (China); OSTI
2. Colorado State Univ., Fort Collins, CO (United States)

Afforestation is recommended as an effective approach for carbon sequestration and environmental benefits. However, it remains less clear, and sometimes controversial, regarding how afforestation may impact soil inorganic carbon (SIC), a crucial component of the ecosystem carbon pool. Here, using field data from 619 afforested plots and 163 control plots across northern China, we investigated the relative and absolute differences in SIC between afforested and corresponding control plots. Our results suggested that afforestation increased SIC in acidic soils, while decreased SIC in alkaline soils. Fitting a linear mixed model and further a structure equation model, we found that afforestation-induced soil pH change was the most significant factor regulating SIC responses. In particular, SIC was more sensitive to pH change in more arid areas, where both soil pH and SIC stocks were high. Other factors could indirectly affect SIC responses to afforestation through modulating soil pH and soil organic carbon (SOC) dynamics. Moreover, afforestation-induced SIC changes also varied considerably among different species of tree plantations and across different soil depths. Importantly, in plantations of Pinus sylvestris var. mongholica, Pinus tabuliformis, and Populus spp., changes in SIC caused by afforestation were even comparable to that in SOC. Overall, our findings provide a data-based understanding on the comprehensive soil carbon dynamics following afforestation and its underlying mechanisms. With the increased use of afforestation and reforestation as nature-based solutions to climate change, their associated impacts on SIC need to be taken into account, especially in SIC-rich areas.

• Research Organization: Colorado State Univ., Fort Collins, CO (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: SC0022074
• OSTI ID: 1978510
• Journal Information: Global Biogeochemical Cycles, Journal Name: Global Biogeochemical Cycles Journal Issue: 1 Vol. 36; ISSN 0886-6236
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English