We must not forget that there is another thing that affects the growth of trees, and that is the soil. Pines like a sandy soil, while most other trees do not. Certain cedars and cypresses like swampy places where no other trees will grow. Many beautiful meadows and prairies have no trees, because the soil is not well drained.
It is very easy to understand why trees cannot grow where it is dry, but how shall we learn of the effect of cold upon them? Shall we have to take a journey of thousands of miles into the far North, until we finally come to the land called the Barren Lands or tundras, where the trees become stunted and at last disappear—a land where they cannot longer fight against the cold and live?
Fortunately such a long journey is not necessary. All we have to do is to climb a great mountain range, like the Sierra Nevadas, to pass through all the different climates which we would experience on a long journey to the arctic regions.
It is only a few miles from the hot San Joaquin Valley, at the base of the Sierras, where it is so dry that irrigation is necessary, to the summit of the range, where the winter climate is as cold as it is in the arctic regions.
George J. Young
East Vidette, King's River Country, California, showing how, as we approach the summit of the mountains, the trees become smaller.
In going up the mountains we first come to the foothills, where there is a little more rain than in the valley. Here we find oak trees growing. Farther up there is still more rain and we come to the pines. Soon we reach the most wonderful coniferous forest in all the world. Here not only is there a great variety of trees, but because of the favorable climate they grow to a great size. As we approach the summit of the mountains the trees become smaller, and at an elevation of about two miles they shrink to the size of little bushes and finally disappear. They can no longer stand the fierce winds and cold storms of this arctic region.
We have learned now that the trees do not grow haphazard over our country, but that the rain, the temperature, and the soil determine where they can live.
Within the heart of the forest the trees will come again if we cut them down, but upon its borders, where the air is drier, it is more difficult for them to spring up anew. If we cut them down carelessly and allow fires to burn over the surface, and the water to wash away the soil, they may never come back.