Beause we cut down a lot of trees. Often, so many, that the health of a forest is irreparably damaged. A forest is not just a bunch of trees. It is a whole ecosystem, in which the trees anchor the growth of many other plant and animal species, hold the ground together to prevent erosion, and produce a lot of oxygen to support animal life. If you harvest too many of the trees, the local ecosystem stops being a forest and starts turning into something else
Answer: During vigorous exercise your breathing rate increases in order to intake more oxygen
Explanation: during vigorous exercise / activity the body needs more oxygen in order to produce energy so your breathing rate increases in order to reach the demand of more intake of oxygen , and your muscles work harder due to an increase in oxygen demand and how much oxygen the muscles take from the blood during vigorous exercises , BUT during rest we have normal rate of oxygen intake because your body is at rest at that moment .
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Zoning laws establish the uses an area of land can be put to. Zoning's basic purpose is to equally divide the municipality into zones which includes residential, commercial and industrial zones. Separating and use of these zones should be reasonably equal.