Tuesday, July 24, 2012

Your Backyard Woods - Riparian Areas

The riparian area is the transition between water and the land at the edge of streams, rivers, lakes, springs, and wetlands. It is the zone of soil and vegetation that feeds the stream energy in the form of leaf litter and dissolved nutrients, and houses soil organisms at densities and diversities nearly 3 times those found in soil farther away from the water. A riparian area dominated by trees is especially important on small streams where intense interaction between land and water ecosystems occurs. These small streams comprise nearly three-quarters of the total stream miles in the United States.

Wooded riparian areas are important because they do the following:
• Leaves and other debris fall into streams and provide food for insects, amphibians, crustaceans and small fish, all critical to the stream food chain.
• Wooded riparian areas provide diverse habitats for birds and other wildlife.
• Fallen trees (large woody debris) create pools and shelter for fish and preserve stream habitat.
• Fertilizers and other pollutants in water coming from other land uses (crop fields, lawns, etc.) sink into the soil, where tree roots and bacteria remove them before they reach the stream.
• The leafy canopy provides shade that cools the water enabling it to hold more oxygen, which helps fish and other organisms grow.
• Overland flow from other land uses (crop fields, roads, etc.) slows down, spreads out, and sinks into the ground, depositing the soil it carries on the surface.
• Tree roots stabilize stream banks and reduce bank erosion.
• Riparian areas are travel corridors for wildlife between wooded patches.

The riparian area is an extremely important ecosystem in your backyard woods. Different parts of the riparian area have different functions and require different management practices. Trees next to the water help maintain lower water temperature, provide leaves and debris to the water, and keep banks stable. Trees next to the water are usually not removed. Eventually, these trees will fall into the stream and improve fish habitat.

Trees farther away from the bank provide filtration, deposition, and plant nutrient uptake that removes sediment, nutrients, and toxic substances from water moving through the riparian area soil. Periodic removal of trees is acceptable in this area because it removes nutrients stored in tree stems and branches, and it increases nutrient uptake by younger, more vigorously growing trees.
A third zone to your riparian area may be needed if a crop field, pasture, or similar land use is adjacent to the trees. A grass zone can make the tree zones more efficient by changing channel flow into sheet flow. The high number of grass stems slows down and spreads out overland flow better than the litter layer under the trees.

The width of your riparian area will vary by its primary function.
• Wildlife habitat will need a minimum width range between 30 and 300 feet.
• Sediment removal needs a minimum width range between 50 and 150 feet.
• Nutrient removal needs a minimum width range between 35 and 125 feet.
• Water temperature cooling needs a minimum width range between 10 and 60 feet.
• Bank stabilization needs a minimum width range between 10 and 30 feet.
For all purpose use, a minimum width range between 35 and 100 feet is recommended. The wider widths provide the best results. Steep slopes will require wider widths to trap sediment and remove nutrients.  Riparian areas are vital for water quality, fish, and wildlife. If you are fortunate to have water in your backyard woods, restoring or maintaining riparian areas are critical activities.

1 comment:

  1. You could have an entire miniature eco system if you did this properly!

    -Carlos Hernandez