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The Key to Clean Water: Trees and Streams

David WiseOver the last 15 years, our restoration program has assisted more than 5,000 landowners in Pennsylvania in reducing water pollution and improving stream health by planting forested buffers. A few weeks ago, our Facebook fans asked CBF's Watershed Restoration Manager David Wise questions about the Pennsylvania restoration program and the benefits of planting trees along streams. See what he had to say below...

Facebook fan Timothy Shultz asked: Are there any plans for more stream restoration projects in Lancaster, Pennsylvania? We seem to only have two or three plantings a year. With hundreds of miles of streams, it seems we could have a few more plantings a year, given the funding and volunteers.

David Wise: Tim, thanks for your question. There’s a bit of history here. In the past, we were a pretty small operation and the level of restoration we were doing made it very hard to do volunteer plantings (which are enormously energy intensive) and take care of our wholesale restoration program. The good news is that we now have some additional staff and with the additional manpower we have, I think we are much better positioned to make sure that there are plenty of opportunities for volunteers while still working on restoration at the wholesale level. I think you can expect good things, and we are far better positioned than we were 10 years ago.

Facebook fan Amanda Elizabeth asked: What sorts of nutrients can buffers offer to stream animals?

D.W.: I’m going to have to pivot on this one. The real connection between trees and nutrients in streams is that nutrients are usually a pollutant in most local waterways. They are good in small amounts—they are necessary. But in large amounts they are the primary pollutants in local waterways and the Chesapeake Bay. So, nutrients—too many is bad. The connection between trees and streams—by placing trees along streams, those trees are foundational to creating an environment in the stream that allows organisms in the stream to prosper and thrive. The things that live in the stream will actually remove a lot of the nitrogen and phosphorus and help tie up those nutrients so they don't move down the system.

The real nugget here is that by giving stream organisms the [right] temperatures, the type of food, and quantity of food that really make them thrive, those organisms are in a great position to do an awful lot of water quality work by removing excess nutrients from the stream system. A stream that has trees on its banks can remove two to nine times more nitrogen from the stream than a stream without trees on its banks.

Facebook fan Amanda Elizabeth asked a second question: What are some indicators of poor stream health that occur after the destruction of a forrested buffer?

D.W.: The first indicator and predictor is whether there are trees along the stream. Trees have such an enormous role in the basic ecology of Pennsylvania streams. The presence of trees would be a primary indication that a stream is heading in the right direction. Some of the indicators that you would see in the water itself; if you are seeing a lot of stringy algae that would be an indicator of excess nutrients and light levels in the stream. Most Pennsylvania streams are adapted to living under the shade of trees. The whole ecosystem is really set up to thrive best under those shady conditions. 

Many thanks for your questions!


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My question would be this: Which buffers more surface runoff: a buffer x feet wide of native warm season grasses, or a buffer the same width of mesophytic trees?

Thank you!

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