Soil organic carbon dynamics are a key indicator for assessing the success of ecosystem restoration. However, the precise role of soil microorganisms in regulating carbon storage has remained poorly understood, particularly in tropical ecosystems undergoing recovery.

In a study published in Catena, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences uncovered the microscopic mechanisms behind soil carbon sequestration during tropical forest restoration. It showed that when microbes get the nutrients they need, they become powerful allies in locking carbon underground.

The researchers employed a space-for-time substitution approach across a restoration chronosequence in Xishuangbanna, southwestern China. They compared three vegetation types: rubber monoculture plantations(heavily degraded), nearly natural rainforests (partially recovered), and primary rainforests. By combining soil chemistry tests, microbial biomarker analysis, and advanced gene sequencing, they were able to trace how both the composition and behavior of microbial communities changed as restoration advanced.

In the degraded rubber plantations, soil microbes were starved of carbon and phosphorus, which severely limited their activity. As restoration progressed, however, the quality of leaf litter and soil nutrients improved dramatically. This nutritional relief triggered a fundamental shift in microbial life strategies: instead of investing all their energy into rapid reproduction (a “Y-strategy”), the microbes switched to a more balanced approach focused on acquiring resources and tolerating stress (an “A/S-strategy”).

They also found that microbial necromass (the dead remains of soil microorganisms), particularly fungal-derived carbon, is actually the stronger direct driver than plant-derived carbon(from fallen leaves and roots) for soil organic carbon accumulation.

Moreover, they observed that as restoration went on, the assembly of microbial communities became more driven by random chance (stochastic processes) rather than by harsh environmental filters (deterministic processes). This shift indicates a more resilient and healthy microbial network, capable of bouncing back from disturbances.

“Our findings show that tropical plantation restoration can effectively enhance soil carbon storage.It turns degraded farmland into a functioning carbon sink, a natural solution that benefits both climate and biodiversity,” said LIU Wenjie of XTBG.

Rubber monoculture. (Image by CHEN Chunfeng)

Nearly natural rainforests.(Image by CHEN Chunfeng)

Available online: 27 August 2026