Water Quality

How Agroforestry Practices Improve Water Quality

Agroforestry practices are a proven strategy for providing clean water. Riparian forest buffers, for example, are one of the most important practices used for maintaining healthy streams. Trees protect water quality by intercepting non-point source pollutants, stabilizing stream banks, decreasing the frequency and intensity of flooding, and preventing sediment from entering waterways.

Filtering Contaminants

In areas dominated by agriculture, a major goal of efforts to improve water quality has been reducing the flow of nutrients into streams. Perennial vegetation removes nutrients and other chemicals via plant uptake and bacterial degradation of the pollutants. Tree root systems improve the cycling of nutrients, especially nitrogen, and also trap phosphorus and sediments. Agroforestry systems placed higher in the landscape can play this same role and thus reduce pressure on riparian forest buffers.

Sediment Reduction

Sediment loading and deposition are one of the most serious water quality problems globally. Trees filter sediment from stormwater runoff, reducing the amount of sediment entering streams and rivers. By slowing down the water, trees promote infiltration and reduce channel flow and gully formation.

Stabilize Streambanks

Trees along streams protect water quality by stabilizing stream banks. The roots of woody plants located along streams strengthen stream banks, reduce erosion and reduce sediment loss..

Improve Aquatic Habitat

Water temperature is a critical factor influencing aquatic ecosystems. Trees along streams and rivers shade water and moderate water temperature, thus allowing fish and other aquatic species to thrive. Large woody debris is critical for healthy aquatic habitat.

Reduce Flooding and Flood Damage

Reestablishing trees and shrubs in riparian areas can moderate water flows and reduce impacts of flooding. Waterbreaks are planned systems of woody buffers in floodplains that trap debris, reduce sand deposition, increase bank stability and reduce damage to roads and ditches. Woody buffers also allow greater capacity for temporary water storage and slow releases from heavy rains.