Deeply rooted plants may work better than certain grasses for transforming nitrogen because the roots will reach the water moving below the surface of the soil. For forested systems, a simple approach to successional restoration would be to plant one native tree species, one shrub species, and one ground-cover species and then allow natural succession to add a diversity of native species over time, where appropriate and warranted by target community composition and anticipated successional development. Other factors listed below need to be considered in the implementation of this practice. Type and Quantity of Pollutant. Sediment, nitrates, phosphates, and thermal pollutants are effectively reduced by riparian areas.
Riparian forests can also effectively remove nitrates from ground water.
Eroded materials and attached pollutants from upslope areas are trapped on the surface. Riparian forest water quality functions have primarily been studied on cropland watersheds where slope has not been a factor. While sheet flow is not required for effective removal of NPS pollution from runoff passing through a riparian area, concentrated flows must be dispersed before upland runoff enters the riparian area. Nonleguminous hardwoods are the most effective vegetation for nitrate removal. Where shade is critical, taller conifers may be preferred.