Riparian Zone

What is a Riparian Zone? The Benefits of Riparian Zones A riparian zone is the land adjacent Riparian zones provide communities to rivers, lakes, and wetlands where with numerous benefits: the vegetation and soils are strongly influenced by the presence of water. Improved soil and water quality - The size of the riparian zone can Above ground, dense stems of native vary depending upon the landscape. grasses, shrubs, and trees physically It may be a small corridor of vegeta- slow surface runoff and out-of-bank tion that hugs the river or it may be a floodwater, which causes sediment to large network of wetlands stretching be dropped on the soil rather than in far into the floodplain. Riparian the waterway. Fertilizers and other zones are formed as the result of wa- pollutants that originate on the land ter, soil and vegetation interacting are taken up by tree roots and are bro- with one another. Although they ken down by soil microorganisms. make up only a small fraction of the Ashworth Allan Nutrients are stored in leaves, limbs, land, they are among the most valu- Riparian zone of the Red River. and roots instead of reaching the river. able of all landscape types. Bacteria in the forest riparian floor convert harmful nitrates to nitrogen gas, which is then harmlessly released Why are Riparian Zones Valuable? into the air. Below ground, roots improve soil porosity that allows more To understand how riparian zones work, it is important to understand how surface runoff to soak into the soil and improve soil health. Logs that ex- water moves. Surface water flows over the land and can carry sediment, nu- tend into the river also slow down the water and armor the banks prevent- trients, pesticides, and fecal coliform bacteria into water bodies. Pollutants ing erosion. Studies have shown a 30 to 98 percent reductions of nutrients can affect the water body in a number of ways. Excess nutrients can cause sediment, pesticides, and other pollutants in surface and groundwater after algal blooms, fecal coliform bacteria can be an indicator of waste-borne dis- passing through a riparian zone. ease and pesticides can kill or sicken fish and aquatic invertebrates (water bugs). Vegetation slows and filters runoff water above ground, causing sedi- Canopy and shade - Cooler stream temperatures result from the shading ment to settle out and be deposited in the riparian zone. If runoff water does created by grasses and a canopy of trees. Aquatic species, such as fish, not spread over a riparian zone, it cuts channels and flows directly to the need moderate water temperatures. Elevated water temperatures decrease river, rendering the buffer available dissolved oxygen, further degrading water quality. The tree can- ineffective for reducing opy also improves air quality by filtering out windblown sediment and air sediment and sediment- born pollutants caused by erosion, cars, construction, and farm machinery. attached pollutants. Food - Leaves trapped on woody debris and rocks provide food and habi- Local History tat for small bottom-dwelling creatures (i.e., crustaceans, amphibians, in- The riparian zone adja- sects, and small fish), which are critical to the aquatic food chain. cent to the Red River and its tributaries was the site Bank stabiliza- of many early settle- tion - River

Clay County Historical Society Society Historical County Clay ments. Cities were origi- banks in healthy Ice was harvested from the Red River for re- nally located next to riv- riparian zones frigeration. ers and their riparian are stabilized by zones for many reasons: permanent • Water for drinking and washing woody roots and, • Water for various manufacturing processes by deep roots of • Food in the form of fish, birds or mammals native grasses • Ice harvested in winter for food preservation in the summer and wildflowers. •

Grazing and water for animals All river systems Keepers River • A place to dispose of sewage and garbage move across a Landowners often remove vegetation from the river- • Transportation using boats, canoes or barges floodplain, cut- bank causing erosion and slumping. • Clams and their shells used for food and manufacturing ting outside cor- • Wood for fuel in homes, busi- ners of bends. This cutting causes the bank to erode, which may be a ma- nesses, and steam powered boats jor source of sediment. Removing permanent vegetation from the banks • Wood for building construction, and replacing it with lawns, agricultural practices, or overgrazing by live- boats and barge construction, and stock accelerates the bank cutting and slumping process. for manufacturing trade goods • Food and medicine harvested Improved habitat - Riparian zones offer a diversity of habitat. Forest cor- from riparian plants ridors provide crucial migratory habitat for birds, some of which are now • A place for recreation threatened due to loss of habitat. Herons, wood ducks, pheasants, turkeys, turtles, foxes, and eagles utilize the riparian zone. The width and length of Many of these uses were uncon- a riparian zone is important because it provides corridors of travel for dif- trolled and resulted in damage to the ferent wildlife species. A diversity of size, shape, and species of plants river and the riparian zone. Today will ensure the greatest variety of wildlife. we understand the role of riparian zones and efforts are underway to Hold water - Riparian zones increase the water-holding capacity of soil, protect or restore damaged areas. moderating flooding and recharging groundwater supplies. Urban irriga- tion, cultivation, tile drainage, and overgrazing of riparian zones all con- The Living Lab’s riparian zone has tribute to increased flow of water to rivers. Channelization of streams and had a variety of uses. Over the years, rivers removes the natural meanders resulting in decreased water storage it was used to harvest wood, garden, capacity, and increased water flow, and more flooding. Clay County Historical Society Society Historical County Clay recreate, and graze sheep. Some of Steamboats, like the Pluck, used ripar- ian zone trees to fuel their boilers. In those uses combined with the loss of the foreground is a barge loaded with Recreation opportunities - The riparian zone provides op- many trees by Dutch elm disease re- wood products. portunities for recreationists to fish, camp, birdwatch, picnic, sulted in damage to the riparian zone and enjoy other activities. and a degraded river ecosystem. Riparian Zone

Riparian Planting Zones Trees, Shrubs, Grasses and Sedges Several zones are featured within the riparian zone: Plants, like people and animals, prefer to live in certain areas. Plants do not thrive if placed in an environment for which they are not adapted. Appropri- Toe zone - the area between the river bed and the average water elevation. ate plants for riparian restoration include:

Bank zone - the area from the average water elevation to the bankfull ele- • False Indigo - 6-12 feet, vation. Shrubby willows are the most successful woody species for this violet flowers in zone. May/June, yellow fall color Overbank zone - the area between bankfull elevation and overbank eleva- tion. Shrubby willows, dogwood and others can be found here. Alder, • Silver Maple - 75-100 birch, and some larger species of willows will occur in the area nearest the feet, yellow fall color, overbank elevation. fast growing

Transitional zone - the area between the overbank elevation and the flood • Black Ash - 50-75 feet, prone elevation. This area may be wide or narrow depending upon slope golden-yellow fall color and water level fluctuations. There may be standing water in the spring and moist to dry soil in the summer and fall. Plant species do not have to • Green Ash - 50-75 feet, Servie Forest Dakota North be extremely flood tolerant. yellow fall color, fast- Flowers from the Green Ash tree are green- growing, ish-yellow, 1-2 inches long, and produced in large dense clusters. Upland zone- the area found above the flood prone elevation. Grasses, sedges, rushes, ferns, wildflowers, shrubs, and trees may grow in both the • Cottonwood - 90 feet, transitional and upland zones. attractive bark, poor fall color, drops twigs, seeds in a mass of ‘cotton’

Native Species • Hackberry - 60-100 feet, yellow fall color, corky bark, medium to fast At the Living Lab and in most other riparian restoration projects, native growing, long-lived tree plants are used. Since native species are already adapted to local climate and soil conditions, there is a major benefit in utilizing these plants. Native • Quaking Aspen - 60- species generally 80 feet, yellow fall thrive with very little color, attractive trunk, attention, can sur- vive extreme • River Birch - 50-70 weather conditions, feet, golden-yellow fall and provide food color, bronze exfoliat- and shelter for wild- ing bark life. Native trees, shrubs, and grasses • Redosier Dogwood - develop significantly 6-12 feet, white flow- deeper and greater ers in May/June, red (Dede Christopher) root masses than twigs in winter, purple Forest Dakota North crop plants and re- fall color Redosier Dogwood is formed with many cently introduced stems of dark red bark. The flower is about grasses. Native • Sandbar Willow - 4.5- 2 inches in diameter. plants are a better al- 9 feet, narrow deep ternative than invasive and non-native species, which can cause ecological green leaves, spreads by rhizomes, easily transplanted damage to our natural environments. Some invasive plant species, such as buckthorn and purple loosestrife, can invade our prairies, forests, and water • Slew Sedge - 3-4 feet, hairy stems, course textured, bodies, spread quickly and crowd out native plants. spreads by rhizomes Riparian Zone

Wildlife in the Riparian Zone When Do Riparian Zones Many land owners rate viewing Need to be Restored? wildlife from their homes as im- Unfortunately, too few people portant to them. Yet, the landscape understand the importance of ri- design and maintenance tradition- parian zones. Many people de- ally used for lawns destroy or de- stroy riparian zones unnecessar- grade an area’s value as wildlife ily through lack of knowledge. habitat. Conversion of native ri- Real estate developers clear parian zones is especially detri- plants for better views; road mental. A blue grass lawn does not builders bury buffers beneath provide the basic habitat needs of highways; engineers construct food and shelter for most woodland culverts and retaining walls over and aquatic wildlife species. High buffers; farmers cultivate down maintenance lawns require pesti- to the riverbank; and homeown- cides which degrade the surround- ers clear trees right to the water ing habitat and eliminate inverte-

line. Erosion on riverbanks is Keepers River brates that are needed by many accelerated when native vegeta- Removal of vegetation often results in riverbank erosion and slumping. creatures as food.

tion is removed. Non-native species usually have shallow-rooted species that cannot protect soil as well Wildlife species, such as Canadian geese and mallard ducks, may become as deeper-rooted native plants. Destroying riparian zones causes erosion, nuisances when they utilize manicured riverfront lawns are Canadian geese siltation of the river, downstream flooding, increase pollution, damage to and mallard

fisheries and recreation, species and diversity loss and reduction of scenic ducks. These value. The prevention of river pollution and destruction is far more eco- lawns are ideal nomical than restoration after the damage has been done. food sources for ducks and How Can Riparian Zones be Restored? geese. Restoring all natural riparian zones may not be economically or socially ac- ceptable. Methods of restoration include utilizing plant materials Riparian zones (bioengineering), using material such as rocks (hard engineering), or a com- are more than bination of the two. Determining what method to utilize is based upon fre- living plant quency of flooding, availability of plant materials or rocks, access to quali- material. For fied contractors, staff or volunteers, available financial resources, etc. example, standing dead There are many types of streambank soil bioengineering treatments that are and dying trees used to create a living barrier of protection. Most bioengineering treat- provide food, Keepers River Dead trees provide nesting cavities, food and perches for ments involve material that is collected from plants that will easily root nesting cavi- mammals and birds. from a cutting. Most species should be harvested when the plants are dor- ties, and perch- mant. It is best to use plants from similar areas as the river. ing sites. Woodpeckers eat bugs found in dead trees. Ospreys, owls and hawks prefer sturdy dead trees near water for nesting sites. Bald eagles are In addition to stabilizing the riverbank, bioengineering offers other benefits occasionally seen on these same dead trees. Many birds, such as the green that hard engineering does not. Trees, shrubs, and grasses create wildlife heron, perch on dead limbs near rivers and lakes to forage and rest. Snags habitat for birds, fish, insects, amphibians, and mammals. Bioengineering and fallen trees along a shoreline are often used by turtles for basking. Am- is useful for areas that are difficult to access with heavy equipment. Living phibians often take cover under woody objects.

plants are self-repairing. The living shoreline continues to grow and be- come stronger with age. Trees, shrubs, and grasses are natural and have Missing elements of the an aesthetic quality. riparian zone may also be replaced by a variety of Hard engineering can be completed with a high level of confidence and methods. For example, is implemented with standard construction machinery. However, it is wood duck nesting boxes usually expensive, has lower aesthetic quality, and can fail dramatically. are frequently used to re- place the cavities used At the Living Lab, bioengineering using native materials will be the pri- for nesting in dead and mary restoration technique utilized. dying trees that have been lost in a riparian How Wide is a Riparian Zone? zone. Dead or dying The width of riparian zones is important. Depending on the characteris- Keepers River trees are removed by Snags slow down water flow and provide habitat for tics of a river home owners and local fish and aquatic bugs. and its surround- governments, especially ing areas, the in urban areas. In Fargo- size of a riparian Moorhead, over 400 wood duck nesting boxes have been placed in the ripar- zone can and will ian zone, replacing those lost cavities. vary significantly. Though even a In other cases, used power line poles maybe installed to replace large dead small riparian zone trees that are used by ospreys and eagles. is better than none. The larger the pro- tected area, the more likely it will ensure many of the ecological functions

Rocks used to stabilize an outside bend. Keepers River of the river.