In a new study published in Agriculture, Ecosystems and Environment on Nov. 5, Prof. ZENG Fanjiang's team from the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences has unveiled distinct soil organic carbon (SOC) accumulation mechanisms across typical land-use types in hyper-arid regions.

In southern Taklimakan Desert, the researchers examined three ecosystems: natural wetlands, paddies, and desert steppes. Using advanced analytical techniques such as amino sugar and lignin phenol biomarker analysis, enzyme activity assays, and metagenomic sequencing, the researchers identified the unique sources of SOC and the crucial microbial processes that drive them in these desert-oasis ecotones.

They found that natural wetlands exhibited the highest SOC content, with microbial necromass carbon contributing up to 19.9%, primarily dominated by fungal necromass. In contrast, paddies showed the lowest SOC content, with their carbon pool primarily consisting of plant-derived carbon (accounting for 28.7%), which is prone to inducing priming effects and accelerating the mineralization of original SOC. 

In addition, desert-steppes, subjected to drought stress and nutrient limitations, exhibited the least microbial necromass accumulation and the highest degree of lignin oxidation, resulting in relatively poor soil carbon stability.

"Our work clearly identified that microbial life-history strategy—the patterns of growth, reproduction, and survival that microbes employ in a given environment—is the key factor regulating SOC pool stability in hyper-arid regions," said Dr. ZHANG Zhihao, first author of the study.

The study underscores the critical role of natural wetlands in drylands for carbon sink maintenance and suggests that paddy management should prioritize salinity control and balanced fertilization for long-term soil carbon sequestration.

Soil organic carbon accumulation pathways in typical land-use types within a hyper-arid region. (Image by XIEG)