Problem description:

I hope everyone will answer enthusiastically.

Analysis:

An interesting phenomenon can be seen after sawing down trees. On the cross section of the stump, there are circles of concentric circles of different colors and sizes.

These concentric rings are called "annual rings". Tree rings are produced by the annual activities of the cambium. In spring, mild climate and abundant rainfall have great influence on the growth of trees.

At this time, the cambium cells divide vigorously, the newborn cells are large and obvious, and the ducts are large and many. Therefore, the wood is light in color and soft in texture. enter

After entering summer, with the increase of temperature and the decrease of rainfall; Especially in autumn, the weather turns cool, the rainfall is less, the cambium activity weakens, and the cell morphology divides.

Small, with thick cell walls and few ducts, the wood looks dense and hard, and its color is dark. The cells and ducts in the tree repeat once a year from large to small.

The quality changes from loose to dense, thus forming annual rings with different colors and textures-annual rings.

Tree rings represent the periodic changes in the growth environment of trees. Usually, the climate changes once a year, so the annual rings will be changed.

It shows the growth in a year. According to the number of rings, we can infer the age of trees and use it to examine the age of forests. However, due to the rhythm of the stratum,

Some activities can produce several annual rings a year, which are called fake annual rings. Like citrus, it can produce three rings a year. So, this year,

The age of trees in rotation can only be a rough figure.

Tree rings can be used not only to calculate the age of trees, but also to understand the experience of trees and the relationship between trees and the local environment and climate at that time.

Under favorable climatic conditions, trees grow well, xylem increases a lot, and annual rings are wider; On the contrary, the annual rings are narrow. For example, the first year of a tree.

The wheels are generally wide, indicating that they were young and vigorous at that time; Sometimes a tree suddenly appears wide rings after many narrow rings appear.

This shows that in those years when the rings were wide, the environment and climate were suitable and conducive to the growth of trees. In addition, there are eccentric annual rings, indicating that the environment on both sides of the tree is different.

Usually in the northern hemisphere, the south-facing side is warmer than the north-facing side, so the south-facing side has wider rings.

The temperature change on the earth has a cycle of 200 years. By studying the changes of tree rings from 1900 to 1960, it is found that in 200 years.

There are also small cycles of climate change in 33 years, 72 years, 92 years,11year, most of which are multiples of11~1.5 cycle. And 1 1 year,

It happens to be the cycle of sunspot activity, which also shows that the activity of the sun directly affects the change of the earth's temperature.

At present, there is a special drilling tool, which can drill from the bark to the core of the tree and take out a piece with all the annual rings. So you don't need it anymore.

Cut down trees to calculate their age. It is of great significance to understand the climate in the region by studying the changing law of tree rings for making ultra-long-term meteorological forecasts.

Formulate greening plans, etc.