watershed

Watershed

Your woodlot is part of a watershed, and therefore affects the quantity and quality of our water. As a woodlot owner, you have a responsibility to protect the water resource.

Quantity: The trees in your woodlot evaporate about 1/2 of the precipitation though their leaves. The other half flows away. Forests are able to keep this flow even by holding water in the soil. The held water is gradually released during dry periods and recharged during wet periods. A reliable flow of water depends on keeping the soil on your woodlot (Raindrops 1990).

Quality: Forests require sunlight, water, and nutrients. The sun is renewed daily. The water is renewed with the next rainstorm. The nutrients are renewed slowly over many years from the air and rocks. For this reason, the forest needs to continuously recycle its nutrients to remain vigorous. When the leaves and the branches fall back to the ground, they return their nutrients to the soil for other trees to use. Ashes to ashes; dust to dust. Those nutrients carried away in streams are replaced from the air and rocks. The productivity of the forest is decreased when the nutrient outflow is greater than the inflow. Poor water quality (murky water) of the streams draining your woodlot is a symptom of a disrupted nutrient balance. Not only is your forest losing that which supports its growth; the stream is losing its ability to support life (great fishing); the town is losing its clean water; and the nutrients are going to a place not wanted (an already eutrophic lake). See also whole tree harvesting and clearcutting (Raindrops 1990).

The forests along waterbodies are especially important. These forests filter out excess sediment and nutrients from runoff. This filtering is especially important in areas having steep slopes, areas recently harvested, and areas that recieve fertilizers (agricultural fields and suburban lawns). The leaves and branches that fall from the shoreside trees are a source of food for aquatic organisms. The shoreside trees shade the water. The shading keeps the water cool. Cooler water holds more oxygen. More oxygen means more and better game fish. The forests along waterbodies need to be kept healthy, with an intact canopy cover. The best way to do this is to encourage regeneration and multiple canopies. This can be done with different types of partial harvests (Perkey et al. 1993). In Maine, there are laws regarding harvesting in shoreland areas. Visit the shoreland web page to learn more.

Research shows that over 90% of the sediment reaching streams in woodland areas comes from wood roads and skid trails. Up to 20% of the land area in a harvest consists of these roads and trails. In creating these roads and trails, the topsoil is disturbed/removed. It is this topsoil that absorbs water. Without it, water more easily collects and flows, carrying soil and nutrients with it. This is erosion. There are many guidelines that can prevent erosion from these roads and trails.
(Land Use Handbook 1995)

Use BMPs to protect your watershed and the productivity of your woodlot. Read the Harvesting page to prevent erosion.

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