Increased arbuscular mycorrhizal tree dominance exacerbates soil microbial phosphorus limitation in a subtropical secondary forest: Evidence from ecoenzymatic stochiometry

• Soil CB, BG, LAP, and NAG activities declined with increasing AM tree dominance. • Soil ln(CB+BG)/ln(AP) and ln(LAP+NAG)/ln(AP) decreased linearly with elevating AM tree dominance. • Vector angle increased with increasing AM tree dominance. • Increased AM tree dominance exacerbates soil microbial phosphorus limitation. Tree mycorrhizal association is a key determinant of soil microbial resource limitation in forests. However, how altered dominant tree mycorrhizal associations changes soil microbial resource limitation remains unclear in sub/tropical forests. Here, we measured soil cellobiohydrolase (CB), β-1,4-glucosidase (BG), leucine aminopeptidase (LAP), β-1,4-N-acetylglucosaminidase (NAG), and acid phosphatase (AP) activities, microbial biomass, and nutrient availability at 0–10 cm and 10–30 cm depths along the gradients of arbuscular mycorrhizal (AM) tree dominance (3 %∼99 %) in a subtropical forest of China, and used ecoenzymatic stochiometry to clarify the shift in soil microbial resource limitation with increasing AM tree dominance. At each depth, increasing AM tree dominance reduced soil carbon:nitrogen ratio and phosphorus availability but increased soil fungal biomass and nitrogen:phosphorus ratio. Soil CB, BG, LAP, and NAG activities declined, whereas AP activity remained unchanged with increasing AM tree dominance. Irrespective of soil depth, ln(CB+BG)/ln(AP) and ln(LAP+NAG)/ln(AP) decreased linearly with elevating AM tree dominance, whereas vector angle increased with increasing AM tree dominance. Collectively, these shifts in ecoenzymatic stoichiometry indicate an intensification of microbial P limitation with increasing AM tree dominance. In addition, ln(CB+BG)/ln(AP), ln(LAP+NAG)/ln(AP), and vector angle exhibited significant relationships with soil carbon:nitrogen and nitrogen:phosphorus ratios. These findings suggest that increased AM tree dominance exacerbates microbial phosphorus limitation, which would provide insights into the consequences of shifted vegetation composition on nutrient cycling and limitation in subtropical forests.