In a study published in Catena, a research team led by Prof. LI Dejun from the Institute of Subtropical Agriculture of the Chinese Academy of Sciences revealed that lithology, rather than climate, governs microbial resource limitation through soil geochemistry and microbial traits.

Soil microbial resource limitation, as a fundamental driver of biogeochemical cycles and ecosystem functioning, is critical for nutrient cycling. Lithology is a key soil-forming factor shaping geochemistry. However, it remains unclear how lithology regulates microbial resource limitation patterns, influences microbial metabolism and carbon sequestration in subtropical forests.

In this study, researchers selected 42 sampling sites on limestone and clastic rock in subtropical forests of southwest China, and investigated their soil microbial resource limitation. They found that limestone soils exhibited nitrogen (N) limitation or N-phosphorus (P) co-limitation, while clastic rock soils experienced greater microbial carbon (C) and P limitation.

Random forest and structural equation models identified lithology, rather than climate, as the dominant regulator of microbial resource limitation, primarily through its effects on soil geochemistry (e.g., Ca, pH), microbial community composition (e.g., fungi : bacteria ratio), and substrate availability (e.g., dissolved organic C).

By focusing on lithological controls in subtropical forests, this study advances the understanding of microbial resource limitation. It posits that lithology, rather than climate, dictates contrasting C/N/P limitation patterns through soil geochemistry and microbial traits.

Assoc. Prof. XIAO Kongcao, the first author of this study, emphasized that these insights underscore the need to integrate lithological effects into Earth system models, improving the predictions of nutrient cycling and C sequestration under global change.

Diagram illustrating the lithological controls on microbial resource limitation and soil organic C sequestration in subtropical forests (Image by XIAO Kongcao)