vegetation

Impacts on Vegetation

Freezing Effects on Soils and Plants

The Abnormal cold waves are unusually happened events. According to climate scientists and researchers, they have not been common. Thus, the abnormal cold waves affect to organisms which are adapting in their own ways in the Earth. However, an increase in extreme weather events have been observed, and the abnormal cold waves are also. As a result, many problems are occured, especially vegetation could be affected by the cold waves. The impacts on vegetation are caused in various ways.

Effects on Plants directly

Cold waves, which bring unexpected freezes and frosts during the winter season in mod-lattitude zones, can kill plants the early vulnerable stages of growth.

Limits of freezing temperatures and plants are following.

Light Freeze (-1.7~0.1 ℃)
- tender plants killed, with little destructive effect on other vegetation.
Moderate Freeze (-3.9~2.2 ℃)
- wide destructive effect on most vegetation with heavy damage to fruit blossoms, tender and semi-hardy plants.
Severe Freeze (less -4.4 ℃)
- severe damage to most plants. At these temperatures, the ground freezes solid, with the depth of the frozen ground dependent on the duration and severity of the freeze, soil moisture, and soil type.

Reference: <Cold Wave of 2002-03; Impact on Agriculture>, J.S. Samra

Many plants can be damaged or killed by freezing temperatures or frost. This varies with the type of plant and tissue exposed to low temperatures.

Tender plants, like tomatoes, die when they are exposed to freezing. The tender plants don't have tolerence to the cold. Even if they can survive in the winter season, they would not grow generally.

Hardy plants, like radish, tolerate lower temperatures. Hardy perennials, such as Hosta, become dormant after the first frosts and re-grow when spring arrives.

However, the problem is that most plants, whether they can tolerate in normal winter seasons or not, could not survive with the extreme cold waves. It is because not only direct effects of the cold waves (such as heavy snowfall or freezing), but also soils where plant's roots have interactions with.

Effects on Soils

Cold waves can also causes soil particles to harden and frozen, making it harder for plants and vegetation to grow within areas where the cold waves hit.

The frozen condition of a soil must exert direct effects upon the plant roots contained in it. In the high latitudes, roots are encased by repeated freezing and thawing. Also bodies of frozen soil inhinit lateral movement of soil water and prevent downward percolation. Plants may be subjected to severe water loss, perhaps to the extent of permanent damage, by exposure to drying winds while the roots are encased in frozen soil and cannot absorb water.

Effects of Snowfalls
on Plant's Roots.

Heavy snowfall also affects to the plant's roots. In soils unprotected by snow, sudden sharp drops in temperature frequently cause cracks as much as 2 feet wide and 8 feet deep with severe damage ro intersected roots.