Is the dense ring edge of the tree south or north?

Because China is in the northern hemisphere and sunshine is in the south, tree rings are often "sparse in the south and dense in the north".

Trees growing in temperate and tropical areas with alternating rainy and dry seasons have annual rings, while trees growing in areas with little climate change in four seasons have no obvious annual rings.

Tree rings are produced because cambium cells in bark increase rapidly from spring to summer; From autumn to winter, the growth rate of cells slows down. Therefore, the part of plants growing between spring and summer is soft and generous; The part that grows between autumn and winter is narrow and hard. As the trees grow stronger year by year, annual rings are formed.

Extended data:

1, the reason

Tree rings are produced by the annual activities of the cambium. The mild climate and abundant rainfall in spring are beneficial to the growth of trees. This is because the cambium cells divide vigorously, the newborn cells are large and obvious, and the ducts are large and many. Therefore, the wood looks light in color and soft in texture.

After summer, as the temperature rises. Rainfall decreases, especially in autumn, the weather is getting colder and colder, the rainfall is less, the cambium activity is weakened, and the shape of splinter cell becomes smaller. In addition, the cell wall is thick and there are few ducts, so the wood looks dense and hard, and the color is dark.

2. Influencing factors of width

(1) Tree species: For example, poplar and Populus tomentosa have wide annual rings, while boxwood and dogwood have narrow annual rings.

(2) Tree age: The annual rings formed by trees are wider and wider at the initial stage of growth, but gradually narrow with the increase of tree age.

(3) Living conditions: For example, the average annual ring width of the shrub birch in Greenland at 73 degrees north latitude is less than 0.05 mm, but in a botanical garden in Central Europe, the average annual ring width of the same small birch is 1.6 mm.

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