Coarse woody debris decomposition along an elevation gradient alleviates soil microbial P limitation but intensifies C limitation at Wuyishan National Park

Soil microorganisms play a vital role in biogeochemical cycles by transforming plant residues into soil organic matter through catabolic processes, thereby significantly influencing carbon (C) storage. Changes in microbial metabolic limitations serve as important indicators of shifts in resource availability and microbial survival strategies. Coarse woody debris (CWD) decomposition is a stable source of C and nutrients. This process significantly affects microbial metabolism and is influenced by factors like nutrient availability, vegetation, and climate. However, the effect of CWD decomposition on microbial metabolic limitations, particularly across diverse environmental gradients, remains poorly understood. Our study investigated the impact of different decay classes of CWD on soil microbial metabolic limitation along an elevational gradient in Wuyishan National Park. it examines changes in soil properties, microbial metabolic limitation and enzyme activities during CWD decomposition. We observed increased C limitation and decreased phosphorus (P) limitation in soil microorganisms during CWD decomposition. These trends showed consistent characteristics along the elevational gradient, with soil microbial C limitation gradually increasing and P limitation decreasing as elevation increased. This process was regulated by soil pH and oxidase activity. Our study demonstrated that the presence of CWD could modify the soil environment, allowing microorganisms to adjust their nutrient acquisition strategies, a process that would influence soil C turnover. In conclusion, resource constraints during CWD decomposition induced microbial metabolic trade-offs, and shifts in these trade-off strategies may influence soil C storage. This study offers new insights into the interactions among plant residues, soil, and microorganisms, thereby enhancing our understanding of soil C cycling in the context of global climate change.