Accumulation of glomalin-related soil protein to soil carbon storage in forest ecosystems along an elevation gradient.

Abstract

Glomalin-related soil protein (GRSP), a glycoprotein produced by arbuscular mycorrhizal fungi (AMF), plays a critical role in soil organic carbon (SOC) storage in forest ecosystems. However, the factors influencing its variability and contribution to SOC along forest elevation gradients remain poorly understood, limiting our ability to predict how soil carbon sequestration through GRSP will respond to future global warming. Therefore, this study explored the relationships among GRSP and SOC with climatic and edaphic factors along elevation gradients (666-3892 m) spanning diverse forest types in tropical rainforest, subtropical forest, and subalpine forest in Yunnan, Southwest China. Our findings revealed that AMF spore abundance declined, whereas AMF root colonization and GRSP concentrations increased with increasing elevation. GRSP showed a stronger positive correlation with AMF root colonization than with spore abundance, particularly in subtropical and subalpine forests where nutrient availability was higher. A significant positive relationship was observed between GRSP and SOC across all three forest sites, with the strongest association in subtropical forests. These results suggest that GRSP accumulation is sensitive to climate and nutrient cycling, emphasizing the role of AMF activity and GRSP as an AMF-derived compound in mediating SOC storage across elevation gradients, consequently contributing to climate change mitigation.