Agroforestry II Riparian Buffers I Riparian Buffers Benefits

Agroforestry II - Riparian Buffers

I. Riparian Buffers & Benefits

Riparian Buffers § Riparian buffers are the interface between land water. They are adapted to undergo seasonal flooding. Healthy riparian areas provide numerous environmental and social benefits.

A. Improve Water Quality: § Studies show that riparian forests trap nutrients from runoff and retain them. § 80% of nitrogen and phosphorus kept from entering stream.

B. Reduce Flood Damage: § Reduce flood damage to property. § During flood events buffers reduce flood intensity and erosion.

C. Streambank Stabilization: § Native grass, trees & shrubs provide deep & extensive root systems of anchor streambanks. § Stiff stems of native trees and shrubs deflect river flow away from streambanks.

D. Provide Wildlife & Fisheries Habitat: § Wildlife Habitat. § Food, cover variety of birds and mammals. § Fish need sustained water supply, shade, and stream-bank shelter.

II. Riparian Influences A. Watershed impacts

A watershed is the land area that contributes water to a system of stream channels.

Stream Types Across the Landscape (NRCS, 1998)

Stream Balance Equation stream flow X slope = sediment load X sediment size

Natural channel features Floodplain Bankfull Baseflow

Thalweg Channel Axis (J. C. Fong, 1994, reproduced with permission)

Channel Evolution Model (Space vs. Time) II. IV. VI. primary nickpoint oversteepened reach aggradation zone deposits (from NRCS, 1998)

B. Riparian Disturbances § § Dutch Elm Disease (DED) Flooding Herbivore browsing Fire

DED Impacts § DED, as an introduced disease, has created unprecedented destruction of bottomland forests. § Impacts of excessive debris and re-infections will linger for many years.

Flooding Impacts Flooding is most destructive to understory seedlings and saplings. Midstory pole sized trees are frequently killed with extended inundation. Altered hydrology has made destructive summer flooding more frequent and severe.

Herbivore Impacts From pre-settlement times with elk and bison to present browsing by white-tailed deer, herbivores have always had a substantial impact to frequently flooded forests.

Fire § Historic fires have shaped the ecotone boundary between prairie and northern hardwood ecosystems. § Fires, along with flooding, have been dominant impacts shaping the seral stage and species composition of riparian forests along the Red River.

C. Riparian Response to Disturbance - Flooding

Physiological Flood Effects § Rapid depletion of oxygen in top 6” of root zone. § Anaerobic conditions causing root dieback. § Immediate reduction of intake of water and nutrients by roots. § Entire tree is affected by reduced photosynthetic capacity.

Flood Severity § Timing of flood is most important. Summer floods are much more devastating because of active respiration and photosynthetic demands. § Flood extent is also important in determining the percentage of the tree’s crown submerged and the amount of lenticels covered, which prevents gaseous exchange. § Flood duration affects the extent of dieback of root and stem tissue.

Flood Response & Tolerance § A tree’s response to flooding depends on its capacity to develop adventitious roots and lenticels. § A tree’s age and vigor influence the ability to respond to flooding. § Some tree species are more tolerant and better able to respond to flood effects. § Forests are susceptible to insect and disease attack when weakened by flooding.

Flood Recovery § Trees are dependent on the roots function of providing water, nutrients and auxins for tree growth. § Because of the relationship between tree roots and the crown, recovery or decline may last up to 3 -5 years. § Extent of shoot growth is a good measure of trees recovery.

III. Ecological Implications § Riparian ecosystems along the Red River have evolved with disturbances and are resilient. § Diversity is being increased with reduced fire while early successional stages dominate the more flood prone sites. § Increased flooding has allowed establishment of unwanted introduced species.

§ Bur oak is being replaced by more shade tolerant species that are easier to seed. § Riparian buffers are ecotonal and sensitive to environmental changes.

Ecological Considerations for Restoration § Priority should be given to restoration of original flood prone forests to improve riparian width and connectivity. § Restoration should emphasize quick to establish pioneer species to hold sensitive sites. § Plantation maintenance should allow for natural succession. § Introduced and evasive species should be controlled to allow for natural stand establishment and development.

IV. Restoring Riparian Function • 66 feet on each side • Size and composition can be adjusted. • Continuous

Loss of Riparian Function – Upper Watershed

Loss of Riparian Function – Lower Watershed

Restoration Treatments § The current condition of the riparian area will determine the level of treatment and practices needed. § In degraded areas, cease all activities which harm the function or structure of the riparian area. § In highly deteriorated riparian areas, more active management activities may be needed.

Riparian Restoration Practices § Riparian Filter Strips § Planned Grazing Systems & Water Development § Riparian Buffers § Forest Stand Improvement § Bio-engineering for Streambank Stabilization § Wetland Restoration

Riparian Filter Strips § Native grasses and shrubs. § Restoration on ephemeral and intermittent streams. § May be used with buffers lower in the watershed.

Planned Grazing Systems § 3 fold increase in infiltration with corresponding reduction in runoff. § Most effective on the upper watershed.

Water Development § Construction of sediment ponds in upper watershed reduces flooding downstream. § Solar pumps improve riparian areas.

Riparian Buffer Plantings § Restoration buffers stabilize soils and restores forest function § Trees planted in riparian buffers supplement natural regeneration § Planting can improve the vegetative diversity of the riparian area

Forest Stand Improvement § Thinning and Cull tree removal. § FSI improves forest health, vigor and riparian function. Thinning and Cull tree removal.

Natural Streambank Stabilization Bioengineering § Bioengineering is the use of plant materials and bank reshaping to stabilize streambanks

Bio-engineering for Streambank Protection (Park River Bible Camp)

Wetland Restoration § Improve function of riparian areas through restoration of wetlands. § Coordination Best Management Practices including bank stabilization, grass filter strips, riparian forest buffers and

Management of flood prone forests requires a collaborative effort with researchers and resource professionals. Cooperative projects facilitate merging theory and practice to realize successful riparian restoration in the Red River Basin. David Rush, Project Manager Red River Basin Riparian Project 516 Cooper Ave. Grafton, ND 58220 (701) 352 -3550 www. health. state. nd. us/RRBRP North Dakota Game and Fish North Dakota Soil Conservation Districts North Dakota State Water Commission NDSU Extension Service Red River Regional Council Red River Resource Conservation and Development UND Geology Department

Coordinated Restoration Effort § Resource concerns need to be identified by local landowners, Water Resource Board and Soil Conservation District. § Reach restoration needs to be coordinated with RC&D’s, Natural Resource Conservation Service, North Dakota Forest Service and other partners with the Red River Basin Riparian Project.