Sustainability of soil organic carbon in consolidated gully land in China’s Loess Plateau

Abstract

Massive gully land consolidation projects, launched in China’s Loess Plateau, aim to restore 2667 $$\mathrm{km}^2$$ km 2 agricultural lands in total by consolidating 2026 highly eroded gullies. This effort represents a social engineering project where the economic development and livelihood of the farming families are closely tied to the ability of these emergent landscapes to provide agricultural services. Whether these ‘time zero’ landscapes have the resilience to provide a sustainable soil condition such as soil organic carbon (SOC) content remains unknown. By studying two watersheds, one of which is a control site, we show that the consolidated gully serves as an enhanced carbon sink, where the magnitude of SOC increase rate (1.0 $$\mathrm{g\,C}/\mathrm{m}^2/\mathrm{year}$$ g C / m 2 / year ) is about twice that of the SOC decrease rate (− 0.5 $$\mathrm{g\,C}/\mathrm{m}^2/\mathrm{year}$$ g C / m 2 / year ) in the surrounding natural watershed. Over a 50-year co-evolution of landscape and SOC turnover, we find that the dominant mechanisms that determine the carbon cycling are different between the consolidated gully and natural watersheds. In natural watersheds, the flux of SOC transformation is mainly driven by the flux of SOC transport; but in the consolidated gully, the transport has little impact on the transformation. Furthermore, we find that extending the surface carbon residence time has the potential to efficiently enhance carbon sequestration from the atmosphere with a rate as high as 8 $$\mathrm{g\,C}/\mathrm{m}^2/\mathrm{year}$$ g C / m 2 / year compared to the current 0.4 $$\mathrm{g\,C}/\mathrm{m}^2/\mathrm{year}$$ g C / m 2 / year . The success for the completion of all gully consolidation would lead to as high as 26.67 $$\mathrm{Gg\,C}/\mathrm{year}$$ Gg C / year sequestrated into soils. This work, therefore, not only provides an assessment and guidance of the long-term sustainability of the ‘time zero’ landscapes but also a solution for sequestration $$\hbox {CO}_2$$ CO 2 into soils.

Decoupling of land-use net carbon flux, economic growth, and population change in China

“…The change in carbon flux due to land-use change includes vegetation carbon cycle and soil carbon cycle (including aboveground and underground). The direct carbon flux of land use includes the change of carbon emission due to land use, carbon storage per hectare of soil, and carbon absorption in the process of regrowth (Houghton &Nassikas 2017, Li et al 2018, McCalmont et al 2017, Mendoza-Vega et al 2021, Montgomery 2007, Pugh et al 2019, Searchinger et al 2008, Shi et al 2012, van Groenigen et al 2014, Yan et al 2020, Zhao et al 2021, Zhu et al 2019. Extended Data Table 2 shows the carbon emission and carbon absorption coefficient caused by various land-use changes.…”

Impacts of Landscape Evolution on Heterotrophic Carbon Loss in Intensively Managed Landscapes

“…These activities result in accelerated mobilization of soil organic carbon (SOC) from uplands and its burial in bottomlands, which may alter the fate and rate of HCL. In this work, we use a modeling based study (Yan et al, 2019(Yan et al, , 2020 to characterize the HCL and its dependence on erosional and depositional processes due to the rapid soil transport over time in a watershed.…”