Frost dryness

from Wikipedia, the free encyclopedia

In higher plants, frost dryness describes a state of lack of water . This arises from the fact that the plants lose water through transpiration , but cannot absorb water from the frozen ground, as this is bound in the form of ice. Frost drought is particularly important in mountains and in subarctic and arctic habitats. The resulting damage is also referred to as frost drought or winter drought.

Even at low soil temperatures without frost, there can be problems with the water supply and thus plant wilts, as the transport resistance is increased and the roots no longer grow. While plants in the tundra and high mountains can still absorb water even when the ground is partially frozen, the water supply for plants in warm areas is already impaired at 5 to 10 ° C. In citrus plants, for example, signs of dehydration can occur at temperatures above 0 ° C.

Frost drought occurs particularly in locations with little snow, where the ground freezes deep and the parts of the plant extend beyond the snow cover ( phanerophytes ). In terms of time, it occurs mainly in late winter, when the stronger sun leads to higher transpiration.

There are two types of frost drought:

  • The acute collapse of the water supply occurs in plants that quickly open their stomata in winter . They lose a lot of water through perspiration that cannot be replenished from the soil. As a result, the flow of perspiration in the xylem vessels is interrupted , and tension embolisms are formed. Leaves and branch tips can be damaged very quickly.
  • Chronic damage occurs in plants that keep their stomata closed in winter and slowly lose water through the cuticle and periderm . They include the conifers and the deciduous trees.

Individual evidence

  • Walter Larcher: Ecophysiology of plants . 5th edition, Ulmer, Stuttgart 1994, p. 294. ISBN 3-8252-8074-8
  • Matthias Schaefer: Dictionary of Ecology . 4th edition, Spektrum Akademischer Verlag, Heidelberg, Berlin 2003, p. 116. ISBN 3-8274-0167-4

further reading

  • W. Tranquillini: Frost-drought and its ecological significance . In: OL Lange, PS Nobel, CB Osmond, H. Ziegler (eds.): Encyclopedia of Plant Physiology , Volume 12B, Springer Berlin 1992, pp. 379-400.