Whether the Role of Snow Water in the Growth and Development of Ephemeral Plants Is Limited in a Cold Desert?

The Gurbantunggut Desert, a cold desert and a natural habitat of ephemeral plants, is the largest fixed and semi-fixed desert in China. In the desert, precipitation is in the forms of rainfall and snow. Rainfall directly supplies water into the ecosystem, while snow accumulates and melts during early spring which gives a unique role in regard to ephemeral plants’ growth and development in the desert.

The ephemeral layer is an important component of the plant community in cold deserts. Conventional wisdom has it that the ephemeral layer primarily depends on early spring snowmelt water for germination and development. However, this hypothesis has never been subjected to rigorous testing.

At the end of the snow cover season between 2009 and 2011, the researchers, applying four different snow treatments (0, 50%, 100% and 200% snow cover, with 100% representing the natural amount of snow) and using five replicates, monitored the seedling establishment, species diversity and plant growth, population, cover and productivity throughout.

The results show 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 snow cover increased, and plant size was negatively correlated with plant density.

The results also show that increased snow resulted in higher density of ephemeral plants; however, this high density induced strong competition, reducing the body size of individual plants. By the end of the growing season, snow treatments did not induce significant changes in primary productivity of the ephemeral layer. Primary productivity or growth after seedling establishment depended mainly on rainfall that occurred after the snow had melted, not on snowmelt water itself. Thus conventional wisdom was shown to be only partially true.

The findings suggest that snow was important to these ephemeral plants, but its role was limited to seedling establishment. The study was published online in Journal of Vegetation Science in May 2014.