Cool water carries more oxygen and provides a more livable environment for many species of fish. Warmer water of denuded creeks also slightly increases the release rate of pollutants from sediment particles. Riparian zones with trees and other vegetation filter excessive chemicals that wash from lawns, gardens, and fields. In some cases, such as phosphates that cling to soil particles and move down slope in runoff water, the soft soil and leaf litter of the riparian zone act as a trap for the particles. The phosphates stay on-site, absorbed into the soil from which they are taken up by tree roots.
Nitrates move either on the surface or in groundwater.
These chemical, too, can be intercepted and used by tree roots rather than being allowed to enter the waterway as pollution. Few homeowners stop to consider that their trees can have actual monetary value. And, if their trees are killed or damaged, they can actually collect on an insurance claim. Trees have recognized value, in and of themselves. Because trees have value, tree care professionals devised a method in 1951 to determine their monetary value.