CONCLUSION
Nine years of N and P additions to alpine meadows differentially
affected the magnitude and direction of PEs and SOC decomposition
(except with vanillin amendment under N addition), accelerated
substrates (glucose and vanillin) mineralization and but decreased the
microbial CUE. This was mainly associated with the differences in soil
and microbial C:N:P stoichiometric ratios, and substrates
decomposability due to N and P additions. These changes indicated that
long-term N and P additions resulted in greater losses of both easily
degraded C and recalcitrant organic C by microbial respiration and led
to lower C accumulation, thereby lower SOC content in the topsoil
compared with Control, in particular P addition (Figure 5). Therefore N
and P additions would weaken the soil functioning as a C pool of alpine
meadows.