Plant activity beneath the snow

In alpine plants, winter dormancy may be seen in the development of specialised overwintering buds, while the rate of growth, respiration, or photosynthetic activity of plants beneath the snow are relatively slow. Carbohydrate reserves that accumulate in the plant (particularly in the crown and roots) in the late summer and autumn are preserved over winter and these provide an important source of material for the flush of growth that occurs in many species after the snow melts and temperatures start to rise. The winter snow cover, while considerably reducing light penetration to the underlying plants, acts as a blanket to reduce water loss and moderate plant temperatures, the latter often keeping in the range of 0-2?C. This will protect many species from damage by air temperatures as low as -12?C, which are common in the Australian alps above the snow during the winter. The periods of low, but not extreme, temperature maintained under the snow can be important in controlling the development of many species. Vegetative shoots may require a period of cold (vernalization) before they can be induced to initiate flowers, while the premature opening of flowers before the spring melt may be prevented in some species, as they will not open until after they have been subject to a prolonged period of low temperature. Seeds formed in the summer and autumn normally do not germinate until the following spring. Low winter temperatures (0-2?C) over a number of months can increase the rate and reduce the optimum temperature for germination, providing the opportunity for more rapid seedling establishment after the snow melt in spring. If global warming should shorten the period of snow cover in the alpine regions of Australia this would be expected to have important (although not entirely predictable) ecological consequences, through changes in the degree of stress and altered patterns of development.