In China, the dense tree rings face north. Trees in China get more sunshine in the south, and they grow fast and have sparse rings. On the contrary, they get less sunlight in the north, the trees grow slowly and the rings are dense.
The factors affecting tree rings are closely related to the growth of trees. There is light, temperature, etc. In the northern hemisphere, the trees on the south side receive more light and grow faster, where the rings are sparse, while the trees on the north side are the opposite. In the southern hemisphere, the north side of trees receives more light and grows faster than the north side, so the annual rings on the north side are sparse than those on the south side.
cause
Cells and vessels in trees change from large to small once a year, and substances change from loose to dense, thus forming annual rings of different colors and textures. Concentric rings on the cross section of perennial woody plants. Trees and shrubs common in temperate zones, usually once a year. In temperate regions, the boundaries of tree rings are obvious. In the tropics, because the climate changes little in a year, the annual rings are not obvious.
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.