Winter Damage as the Result of a Complexity of Constraints

Abstract

Overwintering plants are subject to various constraints. The danger from winter cold is not only due to the primary effect of ice formation in the tissues. Additional threats are presented by the freezing of the water in and on the ground, and by snow accumulation. Especially for plants growing on mountains, the combinations of constraints to which they are exposed in winter vary over only very short distances due to steepness of slope and exposure to radiation and wind (Table 8.1; Figs. 8.1 and 8.2). Plants on sunny habitats are exposed to high radiation in the dormant state, to large, short-term fluctuation of shoot and soil surface temperatures, and to winter desiccation. Plants on windward habitats are likely to suffer from low-temperature stress, mechanical, cooling and desiccation effects of wind and frost drought due to frozen soil, whereas plants in wind-protected habitats where snow accumulates, especially on shaded sites, are safe from very low temperatures and desiccation; winter stress on such habitats depends on snow pressure and on the duration of the snow cover.