 |  Environmental Science: A Global Concern, 7/e William P. Cunningham,
University of Minnesota
Mary Ann Cunningham,
Vassar College
Barbara Woodworth Saigo,
St. Cloud State University
Land Use: Forest and Rangelands
Be Alert BoxesBE ALERT FOR: Water Degradation
In the chapter on water, you will be learning about some major water pollution problems. Although we often think of water pollution as being caused by substances flushed down drains or purposely piped into rivers, land use itself is often a principal contributor. In fact, the information you are learning in this chapter about the destruction of tropical forests illustrates the point. The cycle of destruction begins when loggers cut down selected high-value tropical hardwood trees. The logging and removal process claims quite a few surrounding trees, which created clearings. Wind knocks down even more of the trees, and soon the area is attractive to prospective farmers, who gain access through the newly constructed roads.
Logging in itself may or may not accelerate erosion and, therefore, aquatic pollution, depending upon how it is done. The general rule is that plant roots are the best devices to hold soil. So, the more plant cover removed, the greater the problems created for streams and rivers. Farmers effectively complete the process of plant removal that the logging began. Once the ground plants are removed to create farm fields, there is essentially nothing left to hold soil when it rains, so soil erodes rapidly, creating all kinds of problems for rivers. The eroded soil fills in reservoirs, ruining hydroelectric sites and irrigation. It also silts river bottoms and estuaries and can even smother coral reefs.
So, all too frequently, tropical forest destruction triggers a long series of linked degradation events.
BE ALERT FOR: Land Ownership Impact
It is perhaps not immediately obvious how land ownership patterns could have much to do with environmental degradation. But it turns out that they are strongly connected, particularly in the developing countries. As you study this last part of the chapter, notice that four points are made to establish that connection.
1. When people are forced off their land because of shifts to mechanized farming or cash cropping, the displaced often go to marginal lands to try to eke out an existence. Because they are hilly or particularly dry or have other undesirable features, such lands often ought not be farmed at all. When farming is attempted, severe erosion is difficult to avoid. As a result, not only is native habitat destroyed, but soil is lost and rivers become polluted. In fact, our own recently enacted federal Conservation Reserve Program (CRP) was designed to provide incentives to farmers to stop actively farming such lands. 2. Absentee landlords with large holdings are less likely to care about what happens to their lands, thus removing an incentive for sound land use. 3. Since they do not own the land they till, tenant farmers have no incentive to use conservation practices because they do not stand to benefit from such actions. In fact, your text notes that their rents may increase as a direct result of an improvement in the condition of the land. 4. Where large farms are tilled by landless peasants, not only does productivity suffer, but soil quality suffers for much the same reason.
One big benefit of having farmers own the land they till is that, by staying on the same land for a long time, they stand to benefit from good land use practices and to be harmed by poor practices, thus fostering good stewardship habits.
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2003 McGraw-Hill Higher Education