Changes in soil organic carbon stocks from 1980‐1990 and 2010‐2020 in the northwest arid zone of China

Abstract

Soil is the largest carbon reservoir in terrestrial ecosystems, and thus minor changes in it can dramatically affect atmospheric CO2 concentrations. In the northwestern arid zone of China, the prediction of soil organic carbon (SOC) changes is often limited by the scarcity of soil samples and the scale and depth of research, which limit the understanding of carbon cycling processes in arid zone terrestrial ecosystems. Therefore, this study produced digital soil maps of SOC stocks (SOCS) for two periods (1980‐1990 and 2010‐2020) at a 90‐m resolution based on historical soil profile data and a random forest model. The results showed that the prediction accuracy for SOCS in the topsoil (0–30 cm) was superior to that of the subsoil (30–100 cm). Among them, the mean annual evapotranspiration, normalized difference vegetation index during the growing season, multi‐year mean temperature, and clay content were the main environmental factors affecting the spatial distribution of SOCS. In the past 30 years, the SOCS of the northwestern arid zone has decreased by 585.50 Tg, with a mean decline of 19.52 Tg C yr−1. The changes in SOCS caused by land‐use conversion and reductions in SOCS were further shown to be attributable to grassland desertification and agricultural reclamation. These findings are valuable for exploring the carbon cycle in terrestrial ecosystems in the context of global climate change and for achieving China's goal of carbon neutrality.

Global sustainable land use and management: Illustrating the linkage between carbon sink and ecological engineering

“…The research regions of this SI ranged from basin scale to continental scale, and included forest, grassland, saline‐alkali land, desert land, and other fragile ecosystem types (Bhardwaj et al, 2022; Chen et al, 2022; Feng et al, 2023; Hashimi et al, 2022; He et al, 2022; Jia et al, 2023; Liu et al, 2022; Ravisankar et al, 2022; Wang et al, 2022, 2023. Xu et al, 2022; Yang et al, 2022; Zhang et al, 2022, 2023). [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…Meanwhile, analysis methods included multiple innovation model combinations as well as meta‐analysis. SD: system dynamics, GIS: geographic information systems, RF Model: random forest model, DNDC Model: denitrification‐decomposition (DNDC) model (Bhardwaj et al, 2022; Chen et al, 2022; Feng et al, 2023, Hashimi et al, 2022; He et al, 2022; Jia et al, 2023; Liu et al, 2022; Ravisankar et al, 2022; Wang et al, 2022, 2023; Xu et al, 2022; Yang et al, 2022, Zhang et al, 2022, 2023). [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…Therefore, it is essential to accurately estimate the spatiotemporal patterns and drivers of carbon sinks in a changing environment. Zhang et al (2022) estimated the spatiotemporal patterns of soil organic carbon stocks in the northwest arid zone of China. The results indicate that land use conversion caused soil carbon sink changes, for example, grassland desertification and agricultural reclamation reduced soil carbon sink.…”

“…Therefore, it is essential to accurately estimate the spatiotemporal patterns and drivers of carbon sinks in a changing environment. Zhang et al (2022) human disturbances, for instance, the degradation of the sensitive alpine grassland led to soil sink reduction (Bardgett et al, 2021). However, the carbon sink dynamics, response, and feedback of ecological process are still unclear.…”

Optimizing nitrogen and phosphorus application to improve soil organic carbon and alfalfa hay yield in alfalfa fields

“…The arid region in Northwest China is expansive and ecologically delicate, containing a substantial amount of stored organic carbon. Nevertheless, recent research indicates a decline in the region's SOC content over the last three decades, resulting in diminished soil fertility and crop yields (Zhang et al, 2022b). Therefore, our objective was to establish a fertilization regime that promotes alfalfa hay production and improves SOC sequestration.…”