If a person quickly cools down under the snow without a jacket, for some plant species a soft carpet of snow is a condition for survival. Why some plants are warm in winter and why others should still be wrapped in a blanket, Ülo Niinemets, tenured professor of plant breeding and plant biology at the Estonian University of Life Sciences, told Novaator.
“Snow, especially soft snow, is a relatively poor conductor of heat. For this reason the snow carpet cushions fluctuations in the outside temperature. If, for example, there is snow on the roof of a house, the heat loss through the roof is also significantly lower. The same rule also applies on the ground: if the snow falls without freezing, the temperature under the snow layer can remain several degrees”, explained Niinemets.
According to Niinemets, whether or not you need to cover plants depends on winter conditions. For example, if severe frosts occur before the snow arrives, exposed frost-sensitive plants can freeze, so the snow is no longer useful.
However, if the snow falls on unfrozen ground with a light frost and does not melt during the winter, coverage is not necessarily necessary. Even tropical plants can tolerate a cold of at least -4 °C for a short time. At the same time in Estonia, where snow often melts in winter and is then replaced by intense cold, Niinemets recommends covering plants anyway to mitigate risks.
For some plants the snow cover is even a condition for survival. “For example, there is no other hope for winter crops such as winter rapeseed and winter wheat. Various fungal diseases can spread on unfrozen soil, and unlike frozen bare soil, winter takes away winter crops or causes frost damage. Crops either don’t recover at all, or they take a long time in the spring. So it’s better for them, when snow falls on slightly frozen ground,” Niinemets said.
If the advantage of winter fruits is that they are usually low when frost comes, i.e. they do not need a thick layer of snow, tall plants such as roses and grapes have more difficulty.
“Everything that is uncovered and outside the snow line tends to freeze. Therefore, they should be bent as much as possible. At the same time, we also grow many varieties of Amur vine and northern vine. They can withstand the winter without being cut down, but after a hard frost they lose their leaves; the outbreak in spring, in turn, takes a long time,” said Niinemets.
2023-12-27 13:31:00
a-reader-asks-are-the-plants-warm-under-the-snow-the-reader-asks