June 2010 Article: Stream Condition in Piedmont Streams with Restored Riparian Buffers in the Chesapeake Bay Watershed, by Leslie L. Orzetti, R. Christian Jones, and Robert F. Murphy.
Overall, buffer age was positively related to improved indices of stream habitat, water quality, and benthic invertebrate metrics, with a time scale of 10-15 years.
Riparian buffer restoration is a tool utilized to reduce the impact of nonpoint source pollution in flowing waters around the world. If implemented correctly, riparian buffers have the capacity to convert and/or store nutrients such as nitrogen and phosphorus. Much research has examined the benefits of these restored areas for water quality control and improvement, but little has been done to validate the long-term efficacy and associated time lags of these buffers in restoring water quality.
This study tested the efficacy of restored forest riparian buffers along streams in the Chesapeake Bay watershed by examining habitat, selected water quality variables, and benthic macroinvertebrate community metrics in 30 streams with buffers ranging from zero to greater than 50 years of age. Results showed that habitat, water quality, and benthic macroinvertebrate metrics generally improved with age of restored buffer. Habitat scores appeared to stabilize between 10 and 15 years of age. Results are consistent with the hypothesis that forest riparian buffers enhance instream habitat, water quality, and resulting benthic macroinvertebrate communities with noticeable improvements occurring within 5-10 years postrestoration, leading to conditions approaching those of long established buffers within 10-15 years of restoration.
[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own!]