Elevational patterns of microbial carbon use efficiency in a subtropical mountain forest.

Wu, Guopeng; Su, Yangui; Wang, Jingjing; Lin, Sinuo; Huang, Zhengyi; Huang, Gang

Microbial C use efficiency (CUE) and turnover are critical to driving the global C cycle because they regulate C flux between soil and atmosphere. However, the elevational patterns of microbial CUE and turnover are still unclear. This study investigated microbial growth, respiration, biomass turnover time, and CUE at two soil depths (0–20 cm and 20–40 cm) across nine sites along an elevational gradient from 864 to 2856 m in a subtropical forest using an 18O-H2O-DNA approach. Microbial CUE increased with elevation in subsoil (20–40 cm), while it was not affected by elevation in topsoil (0–20 cm), and the increasing CUE with elevation was more related to microbial growth rather than respiration. Microbial growth normalized to MBC (qGrowth) increased with elevation, while microbial biomass turnover time decreased, and microbial respiration normalized to MBC (qCO2) was stable with elevation. Soil pH was negatively related to microbial CUE in topsoil and explained the most elevational variation of CUE. Differently, C:N stoichiometric imbalance between soil and microorganisms determined microbial CUE in subsoil. Altogether, our study provides strong evidence that the elevational pattern and driving factors of microbial CUE vary with soil depth, which may improve our understanding of C cycling and sequestration in the subtropical forest soil.

MOUNTAIN forests; MICROBIAL respiration; SOIL microbiology; MICROBIAL growth; FOREST soils

Biology & Fertility of Soils, 2024, Vol 60, Issue 1, p5

0178-2762

Academic Journal

10.1007/s00374-022-01694-1