Exam 13: Land Resources

Correct Answer:

Verified

Forests also provide a variety of beneficial ecosystem services that are related to their role in the hydrological cycle. For one, as the hydrological cycle shows, 75% of water is recycled by transpiration and evaporation. Transpiration is a biological cooling process in which water from the soil is absorbed by roots is transported through plants, and then evaporated from their leaves and stems. We experience this cooling process when we walk into a forest on a hot summer day, to find that the air is cooler and moister than it is outside the forest. Transpiration also provides moisture for clouds, eventually resulting in precipitation. Thus, through transpiration, forests influence climate conditions. The removal of trees in an area would therefore affect transpiration and this would impact local and regional temperature and precipitation. Second, as the hydrological cycle shows, from the water that precipitates on land, 25% of water seeps into the ground or runs off to rivers and streams. In fact, as tree roots hold vast tracts of soil in place, they regulate surface water flow as they absorb, hold, and slowly release water. This moderation of water flow helps protect watersheds as it provides a more regulated flow of water downstream, even during dry periods, and helps control floods and droughts. Forest soils also remove impurities from water, improving its quality. So the removal of trees would mean the loss of the ability to hold soil in place and this would have far-reaching impacts on local watersheds -- from sedimentation due to increased erosion, flooding due to increased surface run-off, and pollution issues due to the loss of the cleansing ability of forest soils.