Study Reveals Regulatory Mechanisms of Soil Organic Carbon in Central Asian Grasslands

A new study led by Prof. LI Yaoming from the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences, has revealed the driving mechanisms and environmental thresholds that govern the storage of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) within the expansive grasslands of Central Asia. The study was published in Geoderma.

As a core part of the world's largest contiguous temperate grassland belt, Central Asian grasslands play a crucial role in the global carbon cycle. However, a comprehensive understanding of how different soil organic carbon fractions form and stabilize across environmental gradients has long remained elusive.

To address this knowledge gap, the researchers collected 1548 soil samples from 355 sampling sites across Central Asian grasslands. They combined interpretable machine learning methods with generalized additive models to quantify the influence of various environmental factors on both MAOC and POC dynamics.

The researchers identified that vegetation productivity acts as the primary driver of both MAOC and POC accumulation.  

Furthermore, they found that MAOC dominates the soil carbon pool in these arid grasslands which remains consistently and significantly higher than POC, indicating that mineral stabilization is the paramount mechanism driving soil carbon storage across the region.

Interestingly, POC exhibits a pronounced threshold response to soil bulk density: levels exceeding a specific critical point strongly inhibit its accumulation; While MAOC exhibits high sensitivity to soil pH and texture, with alkaline conditions imposing a significant constraint on its accumulation.

“Our findings could provide crucial parameters essential for refining the simulation of carbon cycle processes within Earth System Models," said WANG Guangyu, first author of the study.

This study offers a scientific basis for the formation and implementation of tailored grassland carbon management strategies across Central Asia.

Read the full article: https://doi.org/10.1016/j.geoderma.2025.117610 

Contact

LONG Huaping

Xinjiang Institute of Ecology and Geography

E-mail: longhp@ms.xjb.ac.cn

Web: http://english.egi.cas.cn