Long-term effects of grazing exclosure and plateau pika disturbance on soil biochemistry in alpine meadows
摘要
Grazing exclusion is an effective measure of restoring patchily degraded alpine meadows, but a controversy still surrounds it as whether it will have a continuously positive ecological impact on degraded alpine meadows as the duration of exclosure prolongs. Under grazing exclosure, plateau pika disturbance can also alter soil characteristics. To address the uncertaint effects of long-term exclosure and plateau pika disturbance on soil biochemistry in alpine meadows, this study compared soil properties in a 10-year enclosed meadow encompassing both pika-active (FP) and pika-free (FN) zones to those of a regularly grazed area (CK). The results indicated that the light fraction organic carbon content and microbial biomass carbon content in FN were significantly higher than those in CK, but the dissolved organic carbon content and leucine aminopeptidase activity were significantly lower than those in CK. The SOC fractions and soil enzyme activities in FP were significantly lower than those in CK and FN (P < 0.05). Long-term exclosure and plateau pika disturbance significantly altered the composition of the soil bacterial and fungal communities, and the soil bacterial diversity in FN was significantly lower than that in CK and FP. Changes in bacterial diversity were significantly correlated with SOC fractions. Therefore, long-term exclosure on SOC fractions, enzyme activities, and microbial diversity in degraded alpine meadows brings out minimal positive effects, and plateau pika disturbance is not conducive to maintaining ecosystem balance in the alpine meadow.