Stroud Preserve
comes of age
The Stroud Center's federally funded study of riparian forest buffers in West and East Bradford townships in Chester County, turns 10 years of age this year.
Established as a long-term project to demonstrate the effectiveness of riparian (streamside) reforestation in removing non-point source pollution from farmland, the study is already showing positive results.
Although the full effects of the reforestation may still be several years off, the findings to date have demonstrated that the buffer zone removes significant amounts of nitrogen from groundwater that subsequently enters the stream.
The project, which is now part of the Environmental Protection Agency's National Monitoring Program, was initiated to demonstrate and test the Riparian Forest Buffer System developed by the United States Department of Agriculture. It involves three experimental watersheds on the 574-acre Stroud Preserve. These are the Morris Run, Halfway Run and Mine Hill Run, all perennial headwater streams that flow into the Brandywine Creek.
Before the start of the project in 1992, all three watersheds were primarily in crop production under a conservation plan that included contours and crop rotation since the 1980s. The water at the time contained high levels of nutrients and suspended sediments. The Riparian Forest Buffer System was established between 1992 and 1994 in the 40-acre Morris Run watershed. The system consists of three buffer zones - a 15-foot streamside strip of permanent woody vegetation, a 60-foot middle strip of managed forest and a 30-foot grass filter strip on the outside. In the Morris Run a level-lip spreader was added to the outside strip to disperse concentrated overland water runoff. This is a shallow, contoured dip that stops and holds the runoff, letting the water leach into the ground. (See site map.)
On the slopes above the Morris Run, row-crop planting continued on land that had once been tiled with perforated pipes for drainage. The crops are rotated according to U.S.D.A. Natural Resources Conservation Service guidelines and records are kept of crop yields and fertilizer usage.
On the Half Way Run, agriculture was discontinued and the watershed was entirely reforested.
Mine Hill Run was selected as the reference or control watershed. It remains in the same kind of agricultural production as Morris Run. A sparsely forested, brushy zone between the stream and the cultivated land was maintained as it was when the project began in 1992.
The watersheds are monitored regularly, and the measurements are kept in a database.
Denis Newbold, the Center's lead scientist on the project, said that the latest figures show that the buffer is removing about 30 percent of the nitrogen from the water flowing off the cropland into the Morris Run.
The figures also show that the level spreader is doing its work well, removing about 60 percent of the suspended sediments.
The land, once the late Morris and Marion Stroud's Georgia Farm, is now owned by the National Lands Trust. Conservation easements (held by the Brandywine Conservancy) and a research agreement give the Stroud Center long-term control of land-use for scientific purposes.
In addition to measuring the effectiveness of buffer zones, the project will help set guidelines for planting and managing buffer zones and assess the time it takes for reforestation to become established.
A ground-eye view of the level-lip spreader in the Morris Run watershed
