Microbial and enzymatic C:N:P stoichiometry are affected by soil C:N in the forest ecosystems in southwestern China

Microbial and enzymatic stoichiometry have been widely used to reflect microbial nutrient limitations. However, the dominant drivers of microbial and enzymatic C:N:P ratios are not well known, which hinders our understanding of whether microbial and enzymatic stoichiometry can accurately reflect microbial resource limitation. Here, we studied vertical patterns (0–100 cm) of factors influencing microbial and enzymatic C:N:P ratios in five forest ecosystems (one tropical, two subtropical, and two temperate) in southwestern China. Our results showed that microbial and enzymatic C:P were not regulated by soil C:P, while N: P followed the same pattern. This suggests microbial resource status is weakly related to microbial and enzymatic C:N:P ratios and that understanding stoichiometry may be inadequate to disentangle nutritional limitations. Soil C:N affected microbial and enzymatic C:N:P ratios likely by altering microbial community structure in all soil horizons. Overall, our study highlighted the important role of soil C:N in regulating C, N, and P cycles, and challenged current methods for modeling microbial nutrient limitations.