Let’s put the rain forests of Amazon and Africa on hold for a minute and look at our own trees in Britain.
As our glorious, but short summer is ending, I was wondering how the trees over here fair. Even though our British winter is not nearly so cold and severe as polar winters, plants and trees still have to be able to adapt to low temperatures and shortage of food. Freezing temperatures turn water into ice and trees cannot take up water through their roots to enable them to make food (photosynthesis).
A long, good surf and a couple of documentaries later, it turns out that one of the nature’s most incredible transformation happens right in my back garden! Here is a quick run down of how the flora & Fauna of Britain prepares for winter shut down:
It’s common knowledge that trees become bare during winter, but not many people actually know how they keep themselves alive during the bitter cold. On frosty winter days, the water in the soil is frozen, so it cannot be taken up by the roots; the air temperature may be quite warm if the sun is shining, so if leaves were still on the trees they would lose a lot of water and wilt, which would result in the death of the tree. So dropping the leaves before winter sets in, is the most sensible thing a tree can do! They can ‘tick over’ during the winter months using stored energy in their roots.
Trees go through a process similar to hibernation called dormancy, and that is what keeps them alive during the winter. Dormancy is like hibernation in that everything within the plant metabolism, energy consumption, and growth slows down. The first part of dormancy is when trees lose their leaves. Most common UK trees such as oak, ash and beech, shed their leaves in the autumn in preparation for winter. Evergreen trees, such as many conifers do not.
When it’s time for trees to lose their leaves, a chemical called ABA (Abscisic acid) is produced in terminal buds and signals the leaf to break off. ABA also suspends growth, preventing cells from dividing and saves a lot of energy during the winter months. Similar to hibernating animals, that store food as fat, and then use it to run their essential systems during the winter, rather than grow or reproduce.
There are divided opinions to whether you should water your trees before or during winter, the most sound advice I found was by Robert Pitman in “To Water or To Not Water—Preparing trees for winter”. For the full article go to: http://www.uidaho.edu/~/media/Files/Extension/Bannock/Bannock_Trees%20for%20winter.ashx
If you like to read more, go to:
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