Stream Restoration: Ecological Repair Could Take 25+ Years

Learning the science of stream restoration is an ongoing project. In 2009, for instance, the National Science Foundation (NSF) helped fund a project in which University of California at Berkeley researchers built an artificial river bed for learning purposes. The NSF release commented, "Stream restoration is an extremely complex and delicate science. Because there is no formula to create meandering streams. Successful stream restorers almost require a sixth sense to get everything right and set a sustainable environment into motion, and not every restored stream lasts." 

Recently, Eliza Hasselquist and other researchers from Umeå University and the Swedish University of Agricultural Sciences (SLU) had a chance to analyze 13 streams in the Vindel River catchment in northern Sweden, whose restoration began in the 1980s. This gave them the unique opportunity to study streams whose restoration began earlier than the 1990s, which is when more streams worldwide received attention.

While it might sound surprising that a stream in northern Sweden isn't pristine, Sweden had a logging industry. For this reason, streams were often channelized from the 1850s to the 1950s, so that logs could be funneled easily downstream without hitting rocks or tree outgrowths. Rocks were blasted, separating streams from the riparian zone.

The restorations that occurred since the 1980s brought back fish productivity and increased riparian plants, which supply habitat, store carbon, provide shade, and filter water.

"Northern Sweden is a great study system for determining the results of restoration because of the long history of restoration and the lack of urbanization. Most stream restoration in other parts of the world did not get started until the 1990s. So we have a unique opportunity to study the long-term effects of stream restoration," says Eliza Maher Hasselquist.

Hasselquist and the other researchers counted the number of plant species in the streams, finding that timelines for achieving species richness should be increased to 25 years or longer.

"The small number of studies of restored streams have often found inconclusive results after stream restoration and this may be because we are too impatient. These ecosystems took thousands of years to develop, and we expect them to return back to their pre-disturbance state in less than five years? We need to be more patient," Hasselquist said, according to a release. 

One of the key findings of the research is that slopes next to streams should be made as gentle as possible - in order to expand riparian buffer widths. Active seeding with native plants and planting of shrubs, like willow, could also bring positive change. 

Related articles: New Stream Maps Could Aid in Sustainable Development

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