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.