Interspecific difference in N:P stoichiometric homeostasis drives nutrient release and soil microbial community composition during decomposition

Background and aims Tree species can produce litter with large variation in nitrogen to phosphorus (N:P) ratios. Here we examined how litter N:P ratios affected decomposer community composition and nutrient release for two contrasting tree species in the Qinling Mountains, China. Methods Two-year-old Quercus aliena var. acuteserrata and Pinus tabulaeformis seedlings were fertilized using nutrient solutions with varying N:P ratios for four months. The obtained litters with contrasting N:P stoichiometry were left to decompose on nutrient-free quartz sand for 12 weeks with microbial inoculum. Then, the post-decomposition microbial community composition was determined using a phospholipid fatty acid (PLFA) analysis. Results The Q. aliena litter stoichiometry was more homeostatic than P. tabulaeformis litter. Litter N:P ratio was significantly related to litter nutrient loss and mass loss for P. tabulaeformis but not always for Q. aliena. The soil microbial community compositions showed larger fungal to bacterial (F:B) ratios with increasing litter N:P ratios for Q. aliena but not P. tabulaeformis . Conclusion Litter N:P ratio, as determined by species-specific homeostasis, showed an interspecific difference to affect the patterns of litter decomposition dynamics, as well as related soil microbial community composition. The less variation in the soil microbial community composition than plant litter stoichiometric characteristics during decomposition is likely an important mechanism that regulates the balance of biogeochemical cycles in the Qinling Mountains.