Allow water to soak into the ground. Trees and plants, leaves and twigs slow surface runoff, allowing the water to soak into the soil. This helps to reduce peakflow levels in streams and replenishes the groundwater that helps maintain lake levels and stream flows. Stabilize streambanks and lakeshores. Trees and plants along streambanks and lakeshores can reduce soil erosion because their roots hold the soil together, making it more difficult for waves, currents and runoff to wash the soil away.
Plants also reduce the impact of raindrops on exposed soil, decreasing erosion.
In most cases, plants and trees along streambanks are necessary to shade streams, keeping the water from becoming too warm for aquatic life in the summer. Provide food and habitat for aquatic organisms. Fallen leaves and other organic debris from trees are the base of the food chain for aquatic organisms in small forest streams. The pools trap leaves and twigs long enough for microorganisms to decompose them. These microorganisms become food for insects and other invertebrates, which in turn become food for fish.