Agroforestry II
- Riparian Buffers
I. Riparian Buffers & Benefits
Riparian Buffers
 Riparian buffers are
the interface between
land and 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.
III.
IV.
V.
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.
North Dakota Game and Fish
North Dakota Soil Conservation Districts
North Dakota State Water Commission
Grafton, ND 58220
(701) 352-3550
www.health.state.nd.us/RRBRP
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.