Effect of different snow depths on plant traits at individual and functional group levels in an alpine meadow

Seasonal snow cover is a major factor influencing the structure and function of alpine meadows. It also affects the response of alpine plants to environmental heterogeneity at different levels. We studied the effect of a depth gradient of natural snow on the vegetation in an alpine meadow of Kaka Mountain. Firstly, we measured how soil environmental factors varied under different snow depths. Soil water content under deep snow cover was higher than under shallow snow cover. There were significant differences in total nitrogen content, total phosphorus content, and organic carbon content under deep snow and under shallow snow. The soil particle size also differed under deep or shallow snow, both in the early growing season and in mid-season. By comparison the response of plant leaf traits and height in an alpine meadow to different depths of snow cover, it indicates that Primula purdomii had greater ILM (individual leaf  mass) and less SLA under deep snow cover significantly, but Pedicularis kansuensis showed no significant differences of all leaf traits and plant height between different snow cover treatments. Ranunculus tanguticus had greater ILM and plant height but less SLA under shallow snow cover than under deep snow cover. The mid-season flowering species, Leontopodium leontopodioides and Festuca ovina had greater specific leaf area (SLA) under deep snow cover, but Kobresia humilis had better SLA, ILA (individual leaf area) and plant height under shallow snow cover. The later flowering Gentiana sino-ornata indicated similar variation with medium flowering Kobresia humilis. Both ILM and ILA of Saussurea stella were significantly greater under shallow snow cover than deep snow cover. At functional group level, snow depth showed significant effects only on plant height while flowering phenology had significant effects on leaf traits and plant height. For early flowering plants, SLA and plant height were negatively correlated with pH, and between SLA was also negatively correlated with organic carbon, total nitrogen, and sand particle content. For mid-season flowering plants, SLA was positively correlated with pH and sand particle content, and negatively correlated with total phosphorus content. The plant height of mid-season flowering plants was negatively correlated with organic carbon content, total nitrogen content, and total phosphorus content. There was a significant relationship between SLA and plant height in all the different flowering functional groups. The species- and flowering phenology functional-specific response of plant traits on snow depth indicated the survival strategy from different plants in alpine meadows for adapting to environmental change. For the maintenance and management of alpine meadow, it is essential to select appropriate grass cultivars, which can ensure sustainable development of husbandry.