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Why the leaves fall
In autumn, the trees prepare for the cold weather. The leaves first turn yellow and later fall off. Yellow and purple and other hues become more noticeable because of the longer nights and shorter days the leaves produce less chlorophyll, than in the summer. Only alder and lilac outfit doesn't change colors, their leaves no other dyes other than chlorophyll.
But the brightness of autumn leaves is directly connected with the weather: if it is rainy – dull leaves; if it's cold overnight but Sunny during the day – leaves are shiny and their colors bright.
Shorter autumn days encourage trees enhance the outflow of nutrients from leaves to the trunk and to dissociate itself from the foliage of the cork wall. Cells of the tree to the first cold Packed with starch is the reserve food for the winter. In extreme cold, it turns into sugar, and the tree will stand.
With foliage of the same tree in the winter says goodbye in order to reduce the evaporation of water. The lower surface of green leaves is covered with a transparent skin, dotted with small holes-stomata. Through them gets wet. For example, birch evaporates over the summer about seven tons of water. In the winter the luxury of a tree to afford just can't: in the soil there is so much moisture.
Autumn leaf fall is justified even from another point of view. Along with water the tree draws from the soil various mineral salts, but using them completely. The surplus accumulated in the leaves. Dropping leaves, the tree saves himself from poisoning.
In addition, the left leaves less snow will remain on the tree longer guarantee that the branch won't break.
But in the spring when frosts return the tree may "catch a cold". And faster on the southern slopes. There before the trees Wake up from winter hibernation and with the return of cold weather do not have time to slow down the SAP flow.
Source: /users/276
But the brightness of autumn leaves is directly connected with the weather: if it is rainy – dull leaves; if it's cold overnight but Sunny during the day – leaves are shiny and their colors bright.
Shorter autumn days encourage trees enhance the outflow of nutrients from leaves to the trunk and to dissociate itself from the foliage of the cork wall. Cells of the tree to the first cold Packed with starch is the reserve food for the winter. In extreme cold, it turns into sugar, and the tree will stand.
With foliage of the same tree in the winter says goodbye in order to reduce the evaporation of water. The lower surface of green leaves is covered with a transparent skin, dotted with small holes-stomata. Through them gets wet. For example, birch evaporates over the summer about seven tons of water. In the winter the luxury of a tree to afford just can't: in the soil there is so much moisture.
Autumn leaf fall is justified even from another point of view. Along with water the tree draws from the soil various mineral salts, but using them completely. The surplus accumulated in the leaves. Dropping leaves, the tree saves himself from poisoning.
In addition, the left leaves less snow will remain on the tree longer guarantee that the branch won't break.
But in the spring when frosts return the tree may "catch a cold". And faster on the southern slopes. There before the trees Wake up from winter hibernation and with the return of cold weather do not have time to slow down the SAP flow.
Source: /users/276
