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December 8, 2023 4:32 am

Opinion

Is Wood in Streams Always Good? | Opinion

Credit: iStock

by Paul Doscher, New Hampshire Bulletin

In the face of long-term declines in the wild populations of our state fish, the Eastern brook trout, one of the actions being taken across the state and region is putting wood into streams. For many decades, it was assumed that getting wood out of streams was important to protect water quality, bridges, and river banks, and prevent flooding. This thinking has changed, especially when it comes to smaller streams.

Today, Trout Unlimited, the Nature Conservancy, New Hampshire Fish and Game, and other landowners are actively putting wood back into streams to enhance fish habitat. Other species benefit as well, as wood slows the flow of water and allows leaves and other organic matter to accumulate; that, in turn, provides food for aquatic insects and other organisms that are the base of the food chain.

This work, along with replacement of undersized and “perched” culverts (those that prevent the movement of fish upstream) is restoring many miles of habitat for our native fish. It’s important to note that this work takes place primarily on smaller headwater streams and not major downstream rivers. In most cases this wood is well installed to remain in place even during major storms.

One great example is the work done by Trout Unlimited and Fish and Game on Nash Stream in the Nash Stream State Forest. Formerly owned by an industrial paper company, the land had been heavily logged, the stream scoured and then devastated by a flood when a dam failed. After the state acquired the land and the U.S. Forest Service acquired a conservation easement, various public and private groups agreed to work to restore the stream and make its habitat once again suitable to wild, native Eastern brook trout. More than a decade and a million dollars (of public and private money) later, that work has been deemed highly successful.

Since the Nash Stream collaboration began, similar efforts have been taking place across the state. Public agencies like the Natural Resources Conservation Service have been making grants to support stream reconnection and restoration on miles and miles of coldwater streams. Great cooperation among conservation organizations, Fish and Game and others have identified the best places for this work and put both volunteer and professional “boots on the ground” to implement successful projects.

Thanks to generally responsible landowners, foresters, and loggers who follow sound forest management guidelines published by the state, the riparian areas along our streams are kept forested and erosion from logging operations rarely do significant damage to water quality and habitat.

Today, the future of our state fish is looking more and more positive. Biologists are finding them in places they were not found in recent decades, and larger numbers of fish are populating restored and reconnected streams.

The New Zealand situation

Interestingly, I am making these observations from afar. With family that lives in New Zealand, and the freedom of retirement, I spend a couple of months each winter on these small islands where it’s summer in January.

New Zealand has been in the news the past few weeks because of tropical cyclone Gabrielle (another term for hurricane) that has devastated much of the northern half of its North Island

Coming after an unusually wet summer, the cyclone dropped an entire year’s worth of rain on parts of the country that host a massive commercial forestry industry. Unlike our forests in New England, these commercial forests are almost entirely one species of tree (radiata pine, native to California) and they are planted in huge blocks. They grow quickly and can be harvested in 25 years. And when they are harvested, it’s with clearcutting.

The soils in northern New Zealand are highly erodible. When the land is exposed to clearcutting, erosion is inevitable, especially on many of the steep slopes of this very hilly region. Cyclone Gabrielle washed millions of pieces of “slash” – the leftover tops and branches of harvested trees – into swollen rivers. The slash filled rivers, demolished bridges, and created log jams resulting in massive loss of farmland and billions in property damage. Clearly, wood in streams in New Zealand is not a good thing.

How did this happen? New Zealand forestland owners acknowledge that climate change has changed the assumptions they had about forest plantations being a way to slow erosion. Storms are now much more damaging than in the past, and forest practices must change in response.

Reporting by Radio New Zealand quoted Grant Dodson, the president of the New Zealand Forest Owners Association, as saying that keeping debris away from waterways with riparian planting, strengthened roads for debris removal, increasing the volume of native trees, and moving slash off site can help reduce the problem of slash. He also said it was possible for slash to be used by the industry as mulch or a source of bioenergy.

Others have gone further, saying that new laws are needed to limit clearcutting in favor of establishing continuous forest cover and permanent native forests.

What a contrast to forestry in New Hampshire, where plantations of exotic conifers are unknown, clearcutting is done sparingly, riparian buffers are almost always respected, and forestry rules do a generally solid job of protecting streams, both small and large. Of course, not all timber harvesting in our state is done well, but on the whole bad operations are the exception rather than the rule.

So, in New Hampshire we intentionally put wood back in streams to enhance them. We do this to mimic what our streams might have looked like before European settlement, when they were home to vibrant populations of native fish. Our forestry practices rarely result in massive erosion, giant rafts of floating slash, and resultant damage to property and people.

Perhaps our experience would be a good example for New Zealand foresters to consider as they figure out how to respond to a future of bigger and stronger storms. And we should also consider whether further improvements will need to be made to our own practices as storms here also grow more intense and harmful.

This story was written by Paul Doscher, a former environmental science professor and contributor to the New Hampshire Bulletin, where this story first appeared.

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