Why restoring vegetation can both store and lose carbon in soils

Restoring vegetation is widely promoted as a natural way to fight climate change, but new research shows that its effects on soil carbon are not always straightforward. A study published in Carbon Research by scientists Lei Deng and Zhouping Shangguan from Northwest A&F University, China, reveals that soil organic carbon (SOC) can either rise or fall in the early stages of vegetation restoration, depending largely on the soil’s initial carbon content.

“Soil is one of the largest carbon reservoirs on Earth, and understanding how it changes with restoration is vital for managing carbon balance and land productivity,” said Deng. “Our work shows that the starting conditions of the soil play a decisive role in whether restoration first adds or releases carbon.”

The research analyzed field data from various long-term restoration projects and identified two contrasting response models of SOC change. In the first model, which occurs in carbon-poor soils, SOC increases rapidly after restoration and then stabilizes. This happens because the newly growing plants provide abundant litter and root exudates that feed the soil’s carbon pool faster than it can decompose.

In the second model, typical of carbon-rich soils, SOC levels first decline before eventually increasing and stabilizing. In these cases, microbial activity accelerates the breakdown of organic matter faster than new carbon inputs can replace it. Soil disturbance from planting and initial erosion can also contribute to early carbon loss. Over time, however, as the ecosystem stabilizes, carbon inputs from plants begin to outweigh losses, leading to net sequestration.

The study suggests that both models eventually converge toward a steady state where soils approach carbon saturation and carbon gains slow to near zero. This “equilibrium stage” reflects the natural limits of how much carbon soils can store under given nutrient and mineral conditions. Nitrogen shortage, for example, can restrict plant growth and carbon input, preventing further increases in soil carbon storage.

“Our findings explain why short-term restoration results can appear inconsistent and sometimes disappointing,” said Shangguan. “But in the long term, vegetation restoration remains an effective strategy for improving soil health and capturing atmospheric carbon.”

The authors emphasize that future regional or global carbon assessments should account for initial SOC levels, local climate, and vegetation types when estimating carbon sequestration potential. They also call for better integration of soil process dynamics into climate and land management models to avoid overestimating restoration benefits.

This research provides a new theoretical framework for predicting soil carbon behavior in restored ecosystems, helping policymakers and land managers design more effective carbon sequestration strategies that match site-specific soil conditions.

=== 

Journal reference: Deng, L., Shangguan, Z. Divergent models of soil organic carbon sequestration related to vegetation restoration. Carbon Res. 4, 2 (2025).   https://doi.org/10.1007/s44246-024-00173-6   

=== 

About Carbon Research

The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.

Follow us on Facebook, X, and Bluesky.