Divergent effects of short-term warming on microbial resource limitation between topsoil and subsoil in a young subtropical Chinese fir forest

Abstract Purpose The effect of warming on microbial resource limitations, especially in resource-poor subsoils, remains unclear. This study investigated the effects of warming on microbial resource [carbon (C), nitrogen (N) and phosphorus (P)] limitation and explored their relationships with soil properties and microbial community structure in topsoil (0-10 cm) and subsoil (40-60 cm).Methods In 2014, ten 2 m×2 m plots were established and assigned to the warming and control treatments at a Chinese fir (Cunninghamia lanceolata) plantation in southern China. Microbial resource limitation with warming treatment was accessed via vector analysis of soil extracellular enzymatic stoichiometry after two years.Results Warming aggravated microbial C limitation in the topsoil but alleviated microbial C limitation in the subsoil, while it shifted the microbial nutrient limitation from P limitation to N limitation in the subsoil. Soil microbial C limitation was explained by soil properties (specifically, ammonium nitrogen) in the topsoil while by microbial community composition in the subsoil based on variance partition analysis. The soil microbial nutrient limitation was explained by soil properties in the topsoil and subsoil. The decrease in actinomycetes abundance in the warming treatment may have led to a decreased microbial C limitation in the subsoil. Conclusion Our study highlighted the differences in warming effects between the topsoil and subsoil. We argue that the microbial resource demand of the subsoil should be further implemented in soil biogeochemistry to improve the prediction of the impact of climate warming on soil C dynamics.