Using Mast-Producing Trees in Riparian Buffer Zones
Riparian buffer zones are areas of vegetation, including trees, shrubs, and grasses, that line the sides of rivers, streams, and other riparian areas and are used to shade and protect the water quality of the aquatic environment. Riparian buffer zones are effective in both rural and urban environments, and they play a key role in maintaining healthy streams and aquatic habitats in both.
Creating or preserving riparian buffer zones has many benefits for both the environment and the landowner, including:
- reduced surface and groundwater pollution from agricultural or urban stormwater runoff
- reduced erosion
- reduced risk of floods
- improved stream health
- increased fish populations
- improved wildlife habitat
- diversified income opportunities
The ideal width of riparian buffer zones depends on the function of the buffer. (All widths are measured in one direction starting from the edge of the water.)
If erosion control is the primary goal, a 50 foot buffer zones is probably adequate. In order to remove pollutants from agricultural or urban runoff, a width of at least 66 feet is best. Most scientists consider the ideal width of a riparian buffer zone to be 100-150 feet. This provides maximum stream health and water quality benefits. However, if wildlife habitat is your primary goal, a width of 300 feet might be even better.
The ideal width of riparian zones also depends on local conditions and the lay of the land. For example, steep streambanks require wider riparian buffer zones than shallow ones.
Riparian buffer zones are divided into three parts, or zones.
Zone 1 is streamside. It should consist of a minimum of 30 feet of large trees planted in about 4-5 staggered rows, as well as dense plantings of native shrubs and ground covers, especially along the stream banks. The first one or two rows of trees should be species that are fast growing and tolerant of wet conditions, such as cottonwoods or willows. These will quickly begin to shade and stabilize the streambanks.
The next two or three rows should consist of slower growing, mast producing hardwoods such as oaks, walnuts, and hickories. These trees provide food and shelter for wildlife, and can be used to diversify the income of the farm or property through fruit or nut sales, lumber sales, and more.
Zone 2 should consist of at least 12 feet of small trees and shrubs. These can include soft mast producing species such as dogwood, chokecherry, and wild plum, to provide food for wildlife and additional income for the property. Zones 1 and 2 provide flood control and wildlife habitat.
Finally, zone 3 should consist of at least 20-25 feet of unmowed native warm season grasses and perennials such as switchgrass. This is the most important zone for reducing erosion and water pollution. Most sediments and pollutants are absorbed by the deep, fibrous roots of the native grasses and forbs before they ever reach zones 1 and 2.
There are a number of federal programs that offer technical assistance, cost-share programs, or grants to landowners interested in installing or improving riparian buffer zones. These include the Conservation Reserve Program.