From the Trees to the Seas
Headwater streams channel water from higher elevations into larger streams and eventually the ocean, but there is another way they help literally feed the waters downstream. Small headwater streams are generally surrounded by overhanging vegetation. This riverside plant life is the start of the food chain through which energy flows and is passed between living things as streams connect and grow larger. Vegetation along headwater streams finds its way into the water in the form of branches, leaves, seeds, or even whole trees, and begins to decay.
As the stream widens, the plants and trees hanging over the waterway separate and allow more sunlight to reach the water, promoting the growth of aquatic bacteria, fungi and aquatic insects that thrive on the decaying plant matter. Farther downstream, these are eaten by larger aquatic insects and small fish, which in turn are consumed by even larger fish and other predators in deeper waters. In this way, trees and other plants that border the small headwaters far upstream of the larger rivers and coastal areas are an essential source of nutrients for the living things that feed the rest of the river system’s food chain.
Viewer Tip: Help protect streamside forests in your area. Leave a buffer of trees and other plants along waterways when clearing land or planning developments. This forested area should extend at least 25 feet away from the river on either side in order to be most effective at filtering pollutants. Protecting and restoring streamside buffers can be as easy as not mowing of a section of lawn that stretches into this area. As the lawn overgrows, a streamside habitat will naturally form to help filter rain water runoff and serve as a food source for downstream waters.
Image courtesy of U.S. Forest Service.
(Sources: Welsch, David J. “Riparian Forest Buffers: Function and Design for Protection and Enhancement of Water Resources.” United States Department of Agriculture. http://books.google.com/books?hl=en&lr=&id=rpSNdMJz4XQC&oi=fnd&pg=PP3&dq=headwater+streams+as+drinking+water+sources&ots=76YEPnMaVR&sig=wY3-DB4k1IZU7tlpe87f2O3P0bo#v=onepage&q&f=false); Middlebury River Watershed Partnership. “Riparian Buffer Zones: Vital to Healthy Rivers and Streams,” http://www.acrpc.info/Downloads/Other/Riparian.pdf)