The role of riparian vegetation in protecting and improving water quality

Authors: DOSSKEY, MICHAEL - Us Forest Service (FS); VIDON, PHILIPPE - Indiana State University; GURWICK, NOEL - Carnegie Institute - Washington; ALLAN, CRAIG - University Of North Carolina; DUVALL, THOMAS - McMaster University; Lowrance, Robert

Submitted to: Journal of the American Water Resources Association
Publication Type: Review Article
Publication Acceptance Date: 8/1/2010
Publication Date: 8/1/2010
Citation: Dosskey, M., Vidon, P., Gurwick, N., Allan, C., Duvall, T., Lowrance, R.R. 2010. The role of riparian vegetation in protecting and improving water quality. Journal of the American Water Resources Association. 46(2):261-277.

Interpretive Summary: The scientific literature is reviewed to provide an overview of the processes by which riparian vegetation influences stream water quality and identify important gaps in the research record. Riparian vegetation influences stream water quality through processes involving both the live vegetation and it’s the dead vegetation such as leaves and branches that fall to the forest floor or in the stream channel. Processes include direct chemical uptake by plants and indirect influences such as supplying litter to channels and soil organic matter, modifying water movement, and stabilizing soil. Some specific processes are more likely from certain vegetation types, such as channel stabilization by large wood and nutrient uptake by faster-growing vegetation.. The overall effect of vegetation type on stream water quality, however, remains less certain than it might if other types of experiments had been conducted. Very little research has been conducted to date on the response of stream water quality to the loss of riparian vegetation or its restoration. Our analysis suggests that the level and timeframe of a response to restoration depends strongly on the degree and timeframe of vegetation loss. Influences of past vegetation may last for many years and decades after vegetation loss. Through the collective action of many processes, vegetation has perhaps the most dominant influence that riparian zones have on stream water quality. The extent to which management of vegetation can exert control on stream water quality remains to be clarified.

Technical Abstract: Riparian vegetation influences stream water quality through processes involving both the live vegetation and its detritus, and, in both the riparian zone and the channel. Individual processes range from direct chemical uptake by plants to indirect influences such as supplying detritus to channels and soil organic matter, modifying water movement, and stabilizing soil. Some specific processes may be more strongly expressed by certain vegetation types, such as channel stabilization by large wood and nutrient uptake by faster-growing species and varieties. An overall effect of vegetation type on stream water quality, however, remains uncertain for lack of research on broader suites of processes that may include compensating or reinforcing interactions. Very little research has been conducted to date on the response of stream water quality to the loss of riparian vegetation or its restoration. Our analysis suggests that the level and timeframe of a response to restoration depends strongly on the degree and timeframe of vegetation loss. Legacy influences of past vegetation may maintain substantial influence for many years and decades after vegetation loss. Through the collective action of many processes, vegetation has perhaps the most dominant influence that riparian zones have on stream water quality. The extent to which management of vegetation can exert control on stream water quality remains to be clarified.