A riparian buffer is planted to create a buffer zone between agricultural land and bodies of water, including floodplains and wetlands.
A riparian buffer can:
- Stabilize eroding banks or shorelines of adjacent water bodies.
- Provide physical separation of agricultural activities from sensitive aquatic areas.
- Protect water quality by acting as an organic filter by trapping sediment laden with nutrients while tree, shrub and plant roots absorb nutrients such as nitrogen, phosphorus and pesticides, etc.
- Supply diverse food and cover for upland wildlife.
- Improve aquatic and terrestrial habitats for fish, wildlife and other organisms.
Prior to developing a planting plan for a riparian buffer, conduct an inventory of the riparian area, including existing vegetation, slopes, soil types, potential problems (e.g. slumping, erosion), signs of current wildlife use, adjacent land use and natural areas. A riparian buffer should be designed to mitigate the impact of land use adjacent to the water body.
Riparian buffers are planted around diverse types of water bodies such as rivers, streams, creeks, lakes, sloughs or wetlands. To be effective the composition of these buffers should be tailored and relevant to each riparian planting type.
Implement a planting option that is suitable for the area chosen to be planted. Some water bodies have irregular perimeters, topography and other physical characteristics that may affect your planting options. For example, a typical planting modification to consider is the variability in the width of land available for planting within the riparian zone. The width of a riparian buffer is a key factor in the overall design of the planting.
As you increase the width of the riparian buffer you enhance the beneficial results generated from the planting. The width you choose is highly dependent on the function of the buffer e.g. bank stability 5.0 metres (m), sediment removal 10-30 m, and wildlife habitat 10-300 m.
An effective riparian buffer strip has two to three vegetation zones, each parallel to the water body. In a two-zone buffer strip, zone one would be composed of trees and shrubs, while zone two would include grass species. To improve bank stability, plant native shrub species such as dogwood and willow.
This type of buffer strip may be most suitable for creeks and streams adjacent to intensively used pasture or cropland. Zone one consists of three to four rows of trees and shrubs planted next to the water body. They can be planted either in rows or a mixed grid orientation to provide a dense diverse plant canopy and rooting structure. Zone two is composed of grassy species. Select grass varieties for their function and match their growth characteristics and requirements to the site. The minimum width of a two-zone buffer strip is 5.0 m.
In a three-zone buffer strip design, trees, shrubs and grasses make up the three zones. Zone one, closes to the bank or shore, consists of trees. Zone two is composed of shrubs or a mixture of trees and shrubs. Grass or grass-forb mixture is planted to the outside of the buffer planting (i.e zone three). The three-zone buffer strip should be a minimum of 10 m wide.
This design is suitable for low order streams with wider flood plains; narrow watercourses with small flood plain; highly erodible lands; or gently sloping shorelines or riverbanks. It is less suitable for wetlands (bogs, fens, swamps, ephemeral wetlands, potholes, etc.) or intensively cropped farmland.
A two or a three zone buffer should have the tree rows planted approximately 2.0 m apart and close to recommended within-row spacing. Riparian buffers planted in a mixed grid orientation will appear more random and natural. The distance between plants should be close to recommended within-row spacing. Increasing the planting density of woody species in a riparian buffer results in earlier canopy closure and reduced weed control issues.
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