Ideas for managing riparian areas and streams

A technical session on riparian and stream management was held in April at the 2010 Annual Meeting of the Oregon Society of American Foresters. The session included three presentations.

New Ideas for Riparian and Stream Management: An Evolving Science

Dr. George Ice, NCASI 

Stream Buffer Design: Regulation of Stream Warming and Some Other Functions

Dr. Mike Newton, Oregon State University (emeritus) 

Riparian Area Logging and Non-Fish-Bearing Streams

Dr. Arne Skaugset, Oregon State University 

All three presentations relied heavily on research being conducted by the Watersheds Research Cooperative (http://watershedsresearch.org/) at Oregon State University. Dr. Newton presented findings from stream temperature studies that tested alternative riparian harvest designs, including a one-sided buffer. Dr. Skaugset’s paper covered work from the Hinkle Creek Watershed Study in southwest Oregon. Dr. Ice’s presentation covered some of the findings from the original Alsea Watershed Study and new observations from the Alsea Watershed Study Revisited.

Following is the abstract of Dr. Ice’s paper.

Early research such as the Alsea Watershed Study (1959-1973) showed that leaving riparian vegetation adjacent to streams greatly moderates immediate water quality impacts associated with logging. Observations about depleted dissolved oxygen levels associated with logging slash and possible fish passage issues further supported retention of riparian vegetation and led to excessive stream cleanouts. Wood recruitment is now recognized as an important riparian function for streams. There is emerging evidence that natural systems need disturbance in order to be productive. Research indicates that riparian disturbance, including harvesting, can be beneficial to fish where in-stream large wood is maintained or rejuvenated. One benefit of riparian management areas (RMAs) is a reduction of aerially applied chemical spray drift to streams, further decreasing potential for adverse environmental impacts. Unanticipated negative consequences of RMAs include unfavorable conditions for regeneration (long-term wood recruitment loss) or light-tight canopies that reduce in-stream primary production and fish productivity. Questions such as “How wide is wide enough?” for RMAs are complicated by multiple RMA dimensions and potential performance measures. RMAs are clearly effective for maintaining certain water quality parameters such as temperature and sediment, but they cannot completely overcome the lack of Best Management Practices in other portions of a watershed. Pollution trading schemes are often confounded by the non-conservative nature of water quality. The future for riparian and stream management should involve optimization to balance or improve stream conditions and values (both short and long term) and sustainable economic benefits. 

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