The Limited Role of Snow Water in the Growth and Development of Ephemeral Plants in the Gurbantunggut Desert

The ephemeral layer is an important component of the plant community in the southern edge of the Gurbantunggut Desert. Due to their short life span, ephemeral plants only develop shallow root systems and may just absorb water from the upper layers of the soil. Therefore, melting snow is considered to be the major water resource that supports the high coverage of ephemeral plants in this desert. Conventional wisdom is that the ephemeral layer primarily depends on early spring snowmelt water for germination and development. However, it is still unclear as to how snow melt affects the growth and development of ephemeral plants.

To analyze the effect of snow water on the growth and development of ephemeral plants in the Gurbantunggut Desert, FAN Lianlian et al. conducted an experiment at the end of the snow-cover season between 2008 and 2011 under four different snow treatments.

The results showed that the ephemeral plant germination and seedling density were significantly influenced by changes in snow cover.Germination, density of mature ephemeral plants and plant coverage rose as snow-cover depth increased. However, the height, rooting depth, numbers of lateral roots and above-ground biomass of individual plants decreased as the snow cover increased and plant size was negatively correlated to plant density. At the layer level, above-ground biomass showed no significant variation between snow treatments. There was also no significant difference in species richness among the snow treatments.

Accumulated snow in winter is an important water resource for ephemeral plants. Increased snow resulted in higher plant density of ephemerals. However, this high density of ephemeral plants induced strong competition between intra and inter-species, which make the density and body size of ephemeral plants exhibit a strong but negative correlation.

By the end of growing season, snow treatments did not induce significant change in primary productivity of the ephemeral layer. Primary productivity or the growth after seedling establishment depended mainly on the rainfall that occurred after the snow had melted, not on snow-melt water itself. The conventional wisdom has been proven to be only partially true. Snow is important to these ephemeral plants, but its role is limited to seedling establishment. The result was published online first in Journal of Vegetation Science in September 2013.