Karst is known as an ecologically fragile region of Southwest China. In recent years, vegetation restoration efforts have gained widespread attention as a strategy to combat ecological degradation. However, few studies have explored how revegetation influences microbial processes that regulate soil carbon decomposition and stabilization.

In a study published in Journal of Environmental Management, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences investigated the impact of vegetation restoration on soil organic carbon components, soil physicochemical properties, and the structure and functional genes of microbial communities involved in carbon cycling.

Through metagenomic approaches, researchers analyzed variations in microbial community characteristics and functional gene expression associated with soil carbon cycling across four distinct restoration stages, i.e., agricultural land, grassland, shrubland, and primary forest.

They found that vegetation restoration significantly increased the content of soil organic carbon and recalcitrant organic carbon, but decreased the dissolved inorganic nitrogen and the proportion of active organic carbon components.

Moreover, researchers found that changes in the soil microenvironment during restoration led to a decline in microbial diversity but enhanced the complexity and stability of microbial co-occurrence networks. Microbial life-history strategies shifted from predominantly r-strategists to more K-strategists.

Furthermore, researchers revealed that the expression of functional genes involved in carbon fixation and degradation of labile carbon compounds decreased, but genes associated with the degradation of recalcitrant carbon compounds increased.

“The shifts in microbial life-history strategies and carbon acquisition modes contribute to higher microbial carbon use efficiency, thereby promoting the stabilization and sequestration of soil organic carbon,” said CAI Xiaoyi from XTBG, one first author of the study.

This study emphasizes the importance of considering soil microbial community traits and their mediated carbon pathways when designing ecological restoration strategies for degraded karst regions. "Policies and practices that promote the development of microbial communities capable of stabilizing carbon will be crucial for achieving our ecological restoration goals," said LIU Wenjie from XTBG, one corresponding author of the study.