You should look after your Christmas tree properly, or you may find all its needles on the floor by Twelfth Night, says university researcher Juho Aalto.
A Christmas tree culled from the forest has about 200,000 needles, estimates Juho Aalto, researcher and Director of the Hyytiälä Forest Station of the University of Helsinki, to forest.fi.
The estimate is based on the assumption that the tree is a normal European spruce that has grown up in the underbrush in a Finnish forest. ’Underbrush’ refers to trees that are clearly shorter and younger than the main growing stock in the forest.
According to Aalto, the stem of a cultivated spruce is thicker than of wild-grown spruces, and therefore it also has more needles than its wild counterparts.
’In a young tree, the ratio between stem diameter and needle mass is fairly constant. As for a cultivated tree, which is stouter, the number of needles can be quite a lot more than in a wild-grown tree. In an extreme case, it can be twice as many, that is, 400,00,’ explains Aalto.
I was actually surprised myself at the number. Though on the other hand, spruce needles are very small; the dry weight of one is normally in the range of 0.005 grams. This means that one gram actually contains about two hundred needles. So it’s no wonder that you still seem to find spruce needles in your house around midsummer.
That does sound like quite a lot of needles.
’I was actually surprised myself at the number. Though on the other hand, spruce needles are very small; the dry weight of one is normally in the range of 0.005 grams. This means that one gram actually contains about two hundred needles. So it’s no wonder that you still seem to find spruce needles in your house around midsummer,’ says Aalto.
’At the same time, this means that a fully grown spruce has millions of needles,’ Aalto continues.
According to an estimate by the Finnish Christmas Tree Growers Association, about 1,4 million spruces will be set up this year as Christmas trees. Somewhat under a million of the spruces sold for Christmas hail from Finnish Christmas tree farms, about 300,000 will be culled by forest owners from their own forests, and about 150,000 trees will be imported.
According to the Finnish Christmas Tree Growers Association, the most important feature of a Christmas tree is that it does not shed its needles too easily. This was the opinion of 21 percent of the people who were asked. What you get free of charge with the tree are up to thousands of little critters, some of which actually become active when finding themselves indoors.
Enough needles to cover your bedroom floor
Juho Aalto describes the total superficial area of the needles in a spruce as ’not inconsiderable’.
’For an ordinary wild-grown spruce, the superficial area of the needles is six square metres, while in a cultivated Christmas tree, it can come up to nine square metres.’
Indeed, the needles shed by the Christmas tree would be enough to cover the floor of an average Finnish bedroom, provided they all fell at once and someone had the energy to spread them evenly on the floor as a Christmas pastime.
Aalto explains that the shedding of needles depends greatly on how gently the tree is treated.
’If you allow the tree to thaw slowly without exposing it to too much heat, then immediately saw off a one-inch round from the stem end, place it in its stand at once, and continue to water it faithfully throughout the holidays, you’ve done all you can to keep the needles from shedding,’ Aalto instructs.
’If, on the other hand, you thaw the tree as quickly as possible, forget about sawing off a bit at the stem end and only add water to the stand when you happen to think of it, the tree will simply dry out, and all of its 200,000 to 400,000 needles may lie on the floor, come Twelfth Night.’
About 60 branches to decorate
What about decorating the tree, how many branches are available for that? According to Aalto, the number of branches depends very much on how the tree has grown.
’An ordinary, wild-grown spruce suitable as Christmas tree, might have about sixty branches, but since the branches of a cultivated tree will have been pruned and shorn and their growth has been restricted, it can have more branches, up to about a hundred,’ Aalto says.
An ordinary, wild-grown spruce suitable as Christmas tree, might have about sixty branches, but since the branches of a cultivated tree will have been pruned and shorn and their growth has been restricted, it can have more branches, up to about a hundred.
This calculation includes what are called important branches. It does not include the small, twig-like branches growing directly out of the stem. The size of the root system left underground after felling can vary a great deal.
’For a tree cultivated in an open field, the root system can be fairly small, while for a tree in the underbrush, the root mass can be as great as that of the aboveground parts,’ Aalto says.
Christmas tree is a carbon storage
The carbon footprint of a Finnish Christmas spruce is smaller than that of a bag of rice. In order to grow, the tree will have needed light, water and carbon dioxide. It has used these for photosynthesis, resulting in the release of oxygen into the atmosphere. At the same time, the tree will have bound carbon dioxide in its tissue.
If you compare this carbon storage with the emissions from an ordinary passenger car using petrol, the same amount of carbon is released as carbon dioxide in the exhaust gases if you drive about 25 to 50 kilometres.
According to Aalto, a spruce that has reached Christmas tree size in a forest will have bound about one kilogram of carbon. In a cultivated spruce, the carbon storage may be up to twice that.
’If you compare this carbon storage with the emissions from an ordinary passenger car using petrol, the same amount of carbon is released as carbon dioxide in the exhaust gases if you drive about 25 to 50 kilometres.’
The dry weight of a spruce is about twice the weight of the carbon it contains.
’The spruce is much heavier than just the carbon, because even quite small ones contain several kilograms of water,’ Aalto explains.