Changes in plant communities, soil characteristics, and microbial communities in alpine meadows degraded to different degrees by pika on the Qinghai–Tibetan Plateau

Abstract

Alpine meadows, the main natural grassland on the Qinghai–Tibet Plateau, are the material basis of plateau meadow husbandry and ecological barrier. However, interference by pika (Ochotona curzoniae) has caused the degradation of alpine meadows to varying degrees. Knowledge about the vegetation, soil characteristics, and microbial community structure and function following degradation is limited. Thus, we studied the changes in vegetation, soil characteristics, and microbial communities in alpine meadows in Qinghai under different degrees of pika-induced degradation (non-degraded “CK”; lightly degraded “LD”; moderately degraded “MD”; and heavily degraded “HD”). The results showed coverage and biomass of the vegetation and species diversity decreased as the degree of degradation increased, and the dominant vegetation changed from members of the family Gramineae to poisonous plants. As the degree of degradation increased, total nitrogen (TN), available nitrogen (AN), and organic matter (OM) in the soil increased first and then decreased, while total potassium (TK), available potassium (AK), and available phosphorus (AP) increased. Among alpine meadows with different degrees of degradation, the alpha diversity of bacteria and fungi in the LD plot were significantly lower than that of CK, MD, and HD. Hierarchical clustering results showed that the composition of bacteria in the MD and HD plots was similar, and the classification of fungi among samples was more obvious. Results from a LEfSe showed that the majority of biomarker bacteria were found in the LD plot, but the majority of biomarker fungi were found in the MD plot. In addition, Tax4Fun and FUNGuild prediction analyses showed that compared with other plots, bacteria causing human infectious diseases were significantly higher in MD, there were more saprotrophic fungi in CK, and there was a significant increase in pathogenic fungi in MD and HD. Thus, pika-induced degradation affected vegetation, soil, and microbial community structure and function in the Qinghai–Tibetan Plateau, with fungal communities responding more strongly to the degradation than bacterial communities.