Abstract:

Aims The herbaceous layer is an important component of the plant community of China’s Gurbantonggut Desert, and it primarily depends on early spring snow-melt water for germination and development. However, few studies have shown how the herbaceous layer responds to variability of precipitation. Generally, snow thickness changes in accordance to variability of precipitation. Therefore, our objective was to determine how snow thickness affects the ecological and physiological traits of the herbaceous layer in a typical arid zone.
Methods We used five treatments of snow thickness (0, 50%, 100%, 150% and 200%), and natural snow thickness (100%) was the control. We investigated species number, coverage, density and height of plants in 1 m × 1 m quadrats and used the harvest method to measure aboveground biomass of both the herbaceous layer and the dominant species (Nepeta micrantha).
Important findings Seedling density of the herbaceous layer was positively correlated with the amount of snow, but average height was negatively correlated with it. Also, total aboveground biomass and number of species showed no significant differences among treatments. Plant height and aboveground biomass of the individual dominants were negatively correlated with the amount of snow. For other species in the layer, the average height was also negatively correlated with the snow thickness. The number of seeds germinating and the abundance of herbaceous plants increased with the amount of snow, but species richness was not influenced by snow thickness. Our results suggested that although melted snow is the main water source for herbaceous plants, they have developed a strong buffering capacity against variation in the snow thickness. Therefore, species diversity and net primary productivity of the herbaceous layer can be stable even under strong variation of snow accumulation.

Key words: biomass, Gurbantonggut Desert, herbaceous layer, snow thickness, species diversity