High School Earth Science: Human Actions and the Land - Loss of Soils — Flashcards

Causes of Soil Erosion    
The agents of soil erosion, like other types of erosion, include water, wind, ice, and gravity. Running water is the leading cause of soil erosion, because water is abundant and has a lot of power. Wind is another important cause, because wind can pick up fine particles of soil and carry them long distances. Soil erosion is as natural as any other type of erosion, but human activities have greatly accelerated soil erosion. Any activities that remove vegetation, disturb the soil, or allow the soil to dry out are likely to increase the rate of soil erosion. Such activities include farming, livestock grazing, logging, mining, construction, and recreation.    
- Farming is the most significant activity that accelerates soil erosion because of the amount of land that is farmed and how greatly farming disturbs the soil. If farmers use traditional farming methods, they remove native vegetation and plow the soil before planting. Because most crops grow only in spring and summer, the soil is left bare and exposed during the rest of the year.    
- Grazing animals expose soil by eating the plant cover. They also disturb the ground with their sharp hooves.    
If too many animals graze the same area, it becomes overgrazed and subject to serious erosion.    
- Logging removes trees that protect the ground from soil erosion. Tree roots hold soil, tree canopy protects soil from hard rain, and dead leaves cover the forest floor and protect the soil. Heavy logging equipment contributes to soil erosion by wearing down vegetation and disturbing the soil.    
- Surface mining removes ground cover and disturbs the soil, leaving it vulnerable to erosion.    
- Construction of buildings and roads churns up the ground and exposes soil to erosion. Paved areas such as parking lots also contribute to erosion by not allowing rain to soak into the ground, thereby increasing runoff.    
- Recreational activities may accelerate soil erosion. Off-road vehicles kill plants and make ruts in soil. In some delicate habitats, even hikers’ boots can leave the ground bare and exposed to agents of erosion.