Because human beings can understand cause and effect, and because we have amassed an increasingly deep body of knowledge about forest processes over the past ten millennia, human influences simply cannot be likened to the blind forces of nature. Since prehistory, human beings have realized benefits from forested lands in the form of spiritual values, medicines, shelter, food, materials, fuel and more. Often, humans have sought to manipulate natural processes so as to compel forest systems to produce more of the goods and services desired by people. At times, human management has become so intensive as to become the primary set of factors under which the forest system operates. Such systems move towards the near total human control found in agricultural systems and cannot be thought of as forests in any natural sense, although they may continue to resemble forests superficially.
Wood is a durable, light-weight, easily worked, waterproof material and fiber source.
It is also a safely handled and easily stored fuel. For these reasons, wood has always been a primary forest product for human populations, and wood and its derivatives have always been the primary forest products for industrial interests. Since wood is an important structural component of any forest, its removal has immediate implications for forest health. Light extraction can be negligible, but intensive harvests can lead to severe degradation, even beyond a forest's capacity to recover. Of course, the specific levels of wood removal that can be tolerated by a forest depend on many factors, including the type of forest involved, the harvesting methods used, the weather, and so on.