To explore the effects of different degrees of degradation on soil microbes and soil enzyme activities in alpine meadows

lightly degraded grassland

moderate degraded grassland and severe degraded grassland of alpine grasslands in the Qilian Mountains of the northeastern Qinghai-Tibet Plateau were chosen as the research objects. Characteristic changes of the number of soil microbes (bacteria

fungus

and actinomycetes)

soil nitrogen bacteria groups (ammonifier

aerobic nitrogen fixing bacteria

anaerobic nitrogen fixing bacteria and nitrifiers

denitrifying bacteria)

soil microbial biomass (soil microbial biomass carbon and soil microbial biomass nitrogen)

and soil enzyme activities (sucrose

urease

phosphatase

and catalase) were determined and analyzed in alpine meadows under different degrees of degradation. The results showed that

for the same soil layer under different degrees of degradation

the number of soil microbes

soil microbial biomass

soil nitrogen bacteria groups

and soil enzyme activities decreased with the increase of degradation degree

and each index was the lowest under severe degradation. The number of actinomycetes

ammoniated bacteria

and denitrifying bacteria in the 10-20 cm soil layer

and the number of bacteria

fungi

actinomycetes

aerobic nitrogen fixing bacteria and denitrifying bacteria in the 20-30 cm soil layer increased in the moderate degraded grassland (p < 0.05). For different soil layers under under the same degrees of degradation

the number of soil microbes

soil nitrogen bacteria groups

soil microbial biomass

and soil enzyme activities decreased with the increase of soil depth. These results provide a new method for assessing the degradation of grasslands

and thus offering important theoretical bases for the restoration of degraded alpine meadows.