Thursday, December 10, 2009

Living in an RPA under the Chesapeake Bay Protection Act

The Regulations of the Chesapeake Bay Protection Act require that a vegetated buffer area of at least 100-feet wide be located adjacent to of all tidal shores, tidal wetlands, certain associated non-tidal wetlands, and along both sides of all water bodies with perennial flow within the Tidewater region. These aquatic features, along with the 100-foot buffer area, are the Resource Protection Area (RPA) and serve to protect water quality by reducing excess sediment, nutrients, and potentially harmful or toxic substances from groundwater and surface water entering the Chesapeake Bay and its tributaries. The RPAs are riparian buffers and provide critical habitat to terrestrial and aquatic species and stabilize stream banks. You can determine if you have a RPA area on a property by using the mapping function from the Assessors Department. Generally, RPA is one of the available mapping layers.

Riparian buffers are noted for their ability to protect and enhance water quality. A properly planted and healthy riparian zone can trap sediment, and reduce or remove nutrients and other chemicals from precipitation, surface waters and ground waters. Riparian buffers are especially important on headwater and small streams that have the greatest amount of water-land interaction and, therefore, have the most opportunities for gaining and transporting sediment. Once sediment has entered the system it can be continually re-suspended as it travels downstream and should be prevented from washing into the stream.

Riparian buffers perform many ecological functions. While required by the Chesapeake Bay Preservation Act for water quality benefits, the advantages realized by a natural or established forested buffer go well beyond clean water, erosion control and control of runoff. The presence of properly vegetated buffers provides biologically diverse habitats both in the water and on land. Watching the wildlife on the edge of the forested zone has provided hours of peaceful pleasure. The buffers are complex ecological systems that connect the upland areas with surface waters providing a transitional area through which both the surface and ground waters flow. Protecting riparian buffers protects human health and welfare by protecting the watershed, one of our most valuable resources.

According to Helms and Johnson a healthy forest has living trees functioning as part of a balanced and self replacing ecosystem. That ecosystem is a complex mix of trees, understory shrubs and groundcover. Over time the process of natural succession causes a change in species composition and structure. Small saplings are developing into the next generation of trees as the older ones die out, and understory trees add valuable functions between the larger dominant species. A riparian, forested buffer may require some degree of maintenance to retain its health and function. Since a forest is a dynamic ecosystem, change is inevitable as vegetation grows and dies.

I had noticed that some of the trees on the garden potion of our land (the area not part of the RPA) seemed to be dying, chocked to death by what appeared to be wineberry and some unknown vine. As an experiment my husband cut down much of the vines on three trees that appeared to by dying the year we moved into the house. Two years later the trees seem to be once more thriving. As I studied the garden I noticed vines growing over many of the trees and began to think that maybe the invasive vines should be cut back on all the trees. This raised the question of the health of the RPA. Wanting to be a good steward of the RPA entrusted to me, I turned to the Virginia Department of Natural Resources.

According to the “Riparian Buffers Guidance Manual” it is practically always best to allow the RPA to evolve on its own. Removal of noxious weeds or dead, dying and diseased vegetation should only be done as necessary to maintain the health of the forest or to prevent fire fuel buildup problems. So I contacted the Virginia Department of Forestry to assess the health of the woodland. The Forester seemed to think that the woodland appeared healthy, though he did not have time to walk the acres within the woodland. The Forester recommended that in the area not part of the RPA that a section of invasive vines be removed and replanted with native species, a dying tree removed and replaced with a native species and some additional tree suggestions for expanding our plantings. The Riparian Buffers Guidance Manual had a wonderful section on the management of woodlands that essentially stated that leaving the woods alone is the best plan.

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