COOPERATIVE EXTENSION SERVICE • UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE, LEXINGTON, KY, 40546
ID-185
Planting a Riparian Buffer Carmen T. Agouridis and Sarah J. Wightman, Biosystems and Agricultural Engineering; Christopher D. Barton, Forestry; and Amanda A. Gumbert, Agricultural Programs
What Is a Riparian Buffer? as pastures. These buffers can be composed of one Streams are dynamic and complex systems that vegetative community but typically consist of three include the active channel as well as its floodplain or zones planted with native species (Figure 1). A zone riparian zone. Riparian zones—which are character- of fast- and slow-growing water-tolerant trees (Zone ized by high levels of interactions between vegetation, 1) is located adjacent to the water; a zone of shrubs soil and water—link terrestrial and aquatic environ- (Zone 2) is located next to the trees, and a zone of ments. These areas have high biotic, structural, and grasses and forbs (Zone 3) next to the shrubs. Ideally, functional diversity. the zones are left undisturbed; however Zone 3 can be mowed or grazed once fully established. Buffers can Urban development and agricultural activities can consist entirely of grass (grass filter strips), but fewer negatively impact stream ecosystems. Streams drain- benefits are provided by that approach. The USDA- ing urban lands often suffer from “urban stream NRCS states that riparian buffers should be 25 ft (7.6 syndrome,” which is characterized by flashy hydrol- m) wide, at a minimum; however, a buffer width of ogy, elevated concentrations of nutrients and con- 200 ft (61 m) is recommended. taminants, altered morphology, decreased amounts of organic matter, and poor biotic richness. Streams What Are the Benefits draining agricultural lands can also be negatively of Riparian Buffers? impacted. Livestock grazing and crop production can compact soils, remove riparian vegetation, alter Riparian buffers offer a number of ecosystems ben- stream morphology, and increase pollutant loads to efits related to water quality, streambank stabilization, streams. One way to reduce the impacts of urbaniza- and habitat. Riparian buffers slow and capture runoff, tion and agriculture on stream ecosystems is through which can improve water quality by trapping and the use of riparian buffers. filtering pollutants such as sediment, nutrients, pes- ticides, herbicides, road salts, and heavy metals. The Riparian buffers are vegetation zones located between root systems of riparian vegetation help to stabilize water bodies such as streams and upland areas such streambanks by holding the soil in place. Leaves and
Figure 1. Cross-section of a riparian buffer with three zones.
Source: Corey Wilson, Landscape Architecture.
Agriculture and Natural Resources • Family and Consumer Sciences • 4-H Youth Development • Community and Economic Development EXTENSION twigs serve as a food source for aquatic bugs called benthics that live in the water and are an important part of the food web. Riparian vegetation can also provide birds and animals with fruits and nuts as well as cover. The shade provided by the canopy of riparian vegetation helps regulate the water’s temperature by keeping it cooler during the summer months. Main- taining a cooler water temperature helps increase the dissolved oxygen level in the water, thus creating a healthier habitat. How Do I Create a Riparian Buffer? Riparian buffers can be created passively (naturally) or actively. Passively creating a riparian buffer is as Figure 2. Newly planted riparian buffer at the Kentucky simple as establishing a no-mow zone. Over time, Horse Park. plants will become established on the site as seeds are introduced from birds and animals, water from the stream, and the wind. This method is an easy and cheap way to create a riparian buffer. However, this passive approach often results in less than optimum conditions, and it can produce a riparian habitat Site Assessment that is harmful. Dispersal of unwanted plants can be When evaluating the location for a riparian buffer, problematic (Table 1) and can create a riparian area information such as land ownership, permits, site covered with non-native invasive species. The species characteristics (climate, soils and geology), utilities, that establish, even if native, can be less effective at and planned future land use should be gathered. If holding together unstable streambanks or providing stream banks are steep and eroding, re-grading may valuable wildlife habitats than riparian buffers that are be necessary prior to planting. Check on permitting actively created. requirements for your selected site prior to perform- Actively creating a riparian buffer typically consists ing any earthwork. Federal, state, and local agencies of six steps: site assessment, planting plan develop- issue permits for a number of activities in and along ment, site preparation, species selection, planting, and streams. The width of the buffer will depend largely protection and maintenance. Figure 2 shows a planted on land availability, but other site characteristics such riparian buffer at the Kentucky Horse Park. as slope, infiltration capacity of the soil, soil qual- ity, and site needs (e.g. what the site will be used for) will factor into the buffer design. For example, if the goal is to filter sediment, a buffer width of 25 ft (7.6 Table 1. Common invasive species in Kentucky. m) may be sufficient for slopes less than 15 percent. Bush honeysuckle Multiflora rose However, if the goal is to reduce soluble nutrient (e.g. (Lonicera maackii) (Rose multiflora) nitrates) and pesticide concentrations in runoff, buf- Japanese honeysuckle Kudzu fer widths of 100 ft (30 m) may be needed. Buffers (Lonicera japonica) (Pueraria lobata) targeting wildlife habitat or temperature control for Winter creeper Garlic mustard fisheries will require wide buffers as well. Also, buf- (Euonymus fortunei) (Alliaria petiolata) fers located on steeper slopes as well as those with Tree-of-heaven English ivy poor-draining soils will likely require greater widths (Ailanthus altissima) (Hedera helix) to remove contaminants from runoff. Soil samples Chinese privet Common reed should be collected to determine pH, moisture con- (Ligustrum sinense) (Phragmites australis) tent, and nutrient content (e.g. macronutrients such as Japanese knotweed Japanese stiltgrass nitrogen, phosphorus). Prior to planting and especially (Fallopia Japonica) (Microstegium vimineum) before beginning any digging, underground utility Purple loosestrife Reed cannarygrass lines should be located and clearly marked. Call 811 to (Lythrum salicaria) (Phalaris arundinacea) locate underground utility lines.
2 Planting Plan Development and fertilizers, and in what amounts. Prior to any When developing a planting plan, one of the first earthwork activity such as digging or mechanically things to do is identify the boundaries and constraints removing vegetation, erosion control measures should of the site. Clearly note property boundaries, utilities, be properly installed to prevent sediment-laden runoff permit conditions, land use considerations, and bud- from entering waterways. Examples of erosion control get. Identify any unique land features such as springs, devices include silt fences, straw bales, and mulching. wet areas, or pedestrian and biking paths. Determine Also, providing the proper noncompetitive ground how many plants are needed. To achieve streambank cover can assist greatly in establishing tree and shrub stabilization and water quality protection, vegeta- species while reducing maintenance and possible in- tion should be planted densely and in a tiered fashion vasion from non-native invasive species. Consult tree (Figure 1). Streambanks should be planted with trees planting guidelines for noncompetitive ground covers able to quickly colonize this environment, such as wil- and other site preparation recommendations for estab- lows, in order to provide protection from the erosive lishing hardwood tree plantings (see UK cooperative forces of stream flows. Trees should be planted at a extension publication Professional Hardwood Notes: rate of 800 trees per acre using 8- by 7- foot spacing. Site Preparation and Competition Control Guidelines Shrubs should be placed 3 to 5 ft (0.9 to 1.5 m) apart for Hardwood Tree Plantings [FOR-107] at http://www. and transplants or plugs of grasses and forbs 1 to 3 ft ca.uky.edu/agc/pubs/for/for107/for107.pdf). Be sure (0.3 to 0.9 m) apart. Consider the time of year when to check for signs of erosion after each rain event. If planting will occur. Ideal times to plant trees are late erosion is occurring, adjust current erosion control autumn through early winter and late winter through measures and/or install additional ones. early spring when the ground is thawed. In Kentucky, Species Selection this is generally November to December and March to April. For grasses, consider whether you want When selecting plants, consider factors such as water cool-season varieties, which should be planted in late tolerance, project goals, natural succession, plant autumn to early winter, or warm-season ones that are availability, and aesthetics. As riparian areas often ex- best planted in late spring, summer or early autumn. perience wetting from floods, selected plants must be When developing a budget, be sure to include costs tolerant of such conditions. Different vegetation types associated with land acquisition, permits, streambank also have different benefits (Table 2). For example, stabilization, soil amendments, plants, vegetation pro- grasses are highly effective at filtering sediment from tection, labor, and maintenance. runoff while trees are best at improving aquatic habi- tat through water temperature regulation and intro- Site Preparation duction of debris such as leaves, twigs, and small logs. Before the site can be planted, it must be prepared. If In all cases, select native species as these plants will the streambanks are unstable, meaning they are steep be best adapted to the local climate. Table 3 contains and eroding, they should be addressed first. Re-grad- a listing of some native species that are appropriate for ing the banks so that they are less steep may be need- planting in Kentucky riparian buffers. Consider the ed. Seek advice from an experienced professional and anticipated changes in the plant community over time check on permitting requirements if streambank re- or natural succession. After preparation, the site may grading is needed. Invasive species should be removed. have bare soils and lots of light. Plant fast-growing Removal can typically be done mechanically or us- ing herbicides approved Table 2. Vegetation effectiveness for select buffer benefits. for use in aquatic areas. Vegetation Type If necessary, the appro- Benefit Trees Shrubs Grasses Low priate soil amendments Streambank stabilization should be added. Soil Filtering sediment Moderate tests are used to deter- Filtering nutrients, pesticides, pathogens mine what amendments Improving aquatic habitat High are needed, such as lime Improving forest habitat Improving field (pasture) habitat Flood protection Visual diversity
3 pioneer species that are adapted to these conditions as Planting well as slower-growing longer-lived species adapted to A wide variety of methods may be used for planting more shaded and crowded conditions. When selecting different types of vegetation. For trees, one-year-old plants, be sure to find out what plants will be avail- bare-root seedlings are often used as they are cost- able for purchase during the projected planting period. effective and generally available at local nurseries. Also give consideration to aesthetics by noting plant Transplanting larger trees is an option but will cost characteristics such as flowering and seasonal foliage more. Shrubs such as dogwoods and willows are color. commonly established from live stakes due to cost,
Table 3. Commonly used native species in Kentucky riparian buffers. Trees Shrubs and Small Trees Grasses Perenial Wildflowers American sycamore Spice bush Switchgrass Great blue lobelia (Plantanus occidentalis) (Lindera benzoin) (Panicum virgatum) (Lobelia siphilitica) Pin oak Arrowwood viburnum Eastern gamma grass Purple coneflower (Quercus palustris) (Viburnum dentatum) (Tripsacum dactyloides) (Echinacea purpurea ) Swamp white oak Eastern redbud Big bluestem Cardinal flower (Quercus bicolor) (Cercis Canadensis) (Andropogon gerardii) (Lobelia cardinalis) Yellow Buckeye Buttonbush River bank wild rye New England aster (Aesculus flava) (Cephalanthus occidentalis) (Elymus riparius) (Aster novae-angliae) White oak Silky dogwood River oats Swamp milkweed (Quercus alba) (Cornus amomum) (Uniola latifolia) (Asclepias incarnate) River birch Rough-leaf dogwood Deer tongue grass Grey goldenrod (Betula nigra) (Cornus racemosa) (Panicum clandestinum) (Solidago nemoralis) Bur oak Greyheaded coneflower (Quercus macrocarpa) (Ratibida pinnata) Swamp chestnut Joe Pye weed (Quercus michauxii) (Eupatorium fistulosum) Red maple (Acer rubrum) Yellow-poplar (Liriodendron tulipfera) Eastern Cottonwood (Populus deltoids) Black walnut (Juglans nigra) Bald cypresss (Taxodium distichum) Black willow (Salix nigra) Tupelo gum (Nyssa sylvatica) Green ash (Fraxinus pennsylvanica var. subintegerrima)
4 but containerized plants can be used. Live stakes or balled and burlapped (B&B) plants may be used. are dormant, unrooted plant cuttings, generally less Containerized plants are grown from seed or cuttings than 2 inches (5 cm) in diameter and 3 ft (0.9 m) in in pots of varying size that are usually filled with a length, that produce roots when planted. Grasses soilless media (bark, sand, peat). The advantage of us- are generally sowed by hand or with the use of a ing containerized stock is that the entire root system hand-held broadcaster, but they can be mechanically is transplanted with the tree which greatly reduces planted with a seed drill or no-till planter. Only the transplant shock. A disadvantage of containerized most common methods for planting trees, shrubs and plants is that the potting material has a tendency grasses will be discussed. to dry. Care must be given to ensure that they are Tree Seedlings watered frequently. Also, containerized plants can be- come root-bound in their pots. Efforts to detangle the When planting small trees such as seedlings (typically roots should occur before planting to ensure proper one-year-old bare-root seedlings from a nursery), pre- growth. Balled and burlapped plants offer the oppor- cautions should be taken regarding timing, transpor- tunity to plant much larger trees with soils that can tation, and handling to minimize stress to improve be matched to that of the transplantation site. Unfor- chances of survival. The ideal time to plant a tree tunately, use of B&B trees pose some special problems seedling is when temperatures are below 50ºF (10ºC) due to their size (heavy, bulky) and may require large and the ground is thawed. During transport, seed- equipment (backhoe, tree spade) for successful trans- lings must be kept cool (33-40º F or 0.5-4.5º C) and plantation. moist. This can be done by wrapping the roots of the seedlings in moist paper towels and storing them in a Planting instructions for containerized and B&B trees refrigerator, then transporting them to the project site are typically provided by the nursery or commercial in coolers. Seedlings can be planted by hand for rough provider. If instructions are not provided, the follow- terrain or small areas using either the slit method (for ing may be used: dibble bars, KBC bars, or sharpshooter spades) or the • Dig a hole just as deep as the root ball and two to wedge method (for use with hoedads or sand shovels). three times as wide. Scarify (roughen) the soil in Refer to Davis et al. (2010) for specifics regarding the the bottom and sides of the hole to encourage root slit and wedge methods. For large areas, mechanical penetration into the native soil. planters are an option. • Remove the moistened root ball from its container. Live Stakes/Cuttings Loosen the roots from the bottom of the ball. If Like tree seedlings, live stakes, also known as cuttings, root-bound, slice some of the roots from the mat- should be planted during the dormant season when ted bottom and sides with a knife or pruner until the ground is thawed. Only certain species such as some hang freely. With B&B trees, remove the willow or cottonwood can be propagated in this man- string or wire that holds the burlap to the root ner. Fresh cuttings can typically be obtained from ball. It is not necessary to completely remove the nearby existing riparian areas. Cuttings should be at burlap, but any plastic wraps covering the burlap least 0.5 in. (1.3 cm) in diameter and 18 in. (46 cm) in (or if used in-lieu of burlap) should be completely length. The top of the cutting should be square and removed. the bottom should be angled to ease planting. Imme- diately soak live stakes in water to preserve moisture. • Place the plant in the empty hole. Step back to Do not harvest live stakes more than 48 hours prior ensure that the stem is straight, and then check to planting. Plant the stakes with the angled (bottom) its depth. The top of the root ball should be even end going into the ground. For softer soils, a rubber with, or slightly above, the surrounding ground. mallet can be used. For firm soils, create a pilot hole • Fill the void around the root ball with the soil that using an iron bar. Plant live stakes so that about 80 was excavated from the hole. Soil amendments or percent of their length is in the ground. Be careful not alternative soil materials should be avoided unless to split the stake or damage the bark when planting. site characteristics dictate otherwise (large rocks Live stakes are typically planted 1 ft (0.3 m) on center or solid clay). for dense planting. • Lightly tamp the soil around the buried root ball Containerized Plants to remove any air pockets. Create a watering basin If larger trees are desired or if transplantation needs by mounding the soil several inches high just to occur during the growing season, containerized beyond the edge of the planting hole.
5 The transplanted trees should be watered if dry condi- Protection and Maintenance tions prevail at the time of planting. With the use of a Once the riparian buffer is planted, it faces threats bucket, watering can be easily performed in riparian from livestock and wildlife browsing, insects, humans, zones due to its close proximity to the stream. Mulch- and unwanted establishment of invasives. The emerg- ing trees in riparian zones is generally not recom- ing vegetation should be monitored to ensure that mended due to the potential for frequent flooding, undesired species are identified and quickly removed which would wash the material away. Staking of trees (Table 1). Fencing can help prevent livestock and wild- may be beneficial. Staking will help support the tree life from grazing and prevent emerging vegetation (especially during flooding events) until the roots from being damaged or destroyed by mowing. Signage are established enough to properly anchor it in place. can be used to mark the boundaries of the riparian Guying of the tree to the stakes should not be too buffer if fencing is not used. Tree shelters, which are tight to allow for some movement of the tree. Remove plastic cylinders that are placed around seedlings to all support wires once the trees are established to create moist microenvironments, have been shown prevent girdling and subsequent mortality. to not only offer protection from mowers and brows- ing animals but also to increase tree growth (Figure Native Warm-season Grasses 3). Fabric mats are another option for improving tree Native warm-season grasses provide dense root growth. Seedlings are placed in the center of a mesh systems and wildlife habitat in riparian buffers. These fabric mat (approximately 18 in by 18 in or 46 cm by grasses can also serve as forage for livestock. Es- 46 cm in size), and the ends of the mat are staked into tablishing native warm-season grasses can be chal- place. These mats prevent competition from herba- lenging, mostly due to competition from already ceous vegetation, such as ground cover species and established cool-season grasses. The most important grasses, and prevent competition for water and nutri- factor to consider when planting native warm-season ents, but they do not offer protection from browsing grasses is controlling competition, which is gener- animals. ally done using herbicides and site preparation. The first step when planting native warm-season grasses is to use herbicide to remove weeds. This step should be done in the year prior to establishment of warm- season grasses before seed formation occurs. Next, prepare the site by removing as much vegetation as possible during the autumn preceding establishment. In the spring, apply an herbicide treatment once six inches of cool-season plant growth has occurred. Seven to ten days before seeding, apply a combination herbicide treatment to kill any remaining cool-season and warm-season plants. Finally, seed warm-season grasses in mid-May to mid-June when the soil tem- perature is above 55°F. Grasses should be seeded to a depth no greater than ¼ inch; otherwise they may not emerge. Consultation with local Kentucky De- partment of Fish and Wildlife Resources (KDFWR) and Natural Resources Conservation Service (NRCS) personnel is recommended when establishing native grass stands. These professionals can provide guid- Figure 3. Use of tree shelter and fabric mat to for ance and often loan equipment to landowners estab- protection from animal browsing and competition. lishing native grasses for riparian buffers and wildlife Minimal maintenance is required for riparian buffers. habitat. Some seed companies offer contracting The site should be visited yearly during the first three services that include herbicide treatments, site prepa- years to check tree survival. If tree survival is low, ad- ration, and seeding of grasses for landowners. ditional plantings may be required.
6 Resources Davis V, J Franklin, C Zipper, and P Angel. 2010. For additional information on riparian buffer plant- Planting Hardwood Tree Seedlings on Reclaimed ing and maintenance, contact your local University Mine Land in Appalachia. Forest Reclamation of Kentucky Extension office, Natural Resource Advisory (No. 7). Conservation Service (NRCS) office, or Kentucky Fox A, T Franti, and M Kucera. 2005. G1557 Planning Department of Fish and Wildlife Resources office. Your Riparian Buffer: Design and Plant Selection. The University of Kentucky Arboretum as well as the University of Nebraska-Lincoln Extension, Insti- Bernheim Arboretum and Research Forest are good tute of Agriculture and Natural Resources. Avail- sources of information. Funding assistance may be able at: http://www.ianrpubs.unl.edu/epublic/live/ available through programs such as the Environ- g1557/build/g1557.pdf. Accessed August 5, 2010. mental Quality Incentive Program (EQIP), Wildlife Habitat Incentive Program (WHIP), or Conservation Gumbert AA, S Higgins, and C Agouridis. 2009. Reserve Program (CRP); contact your local NRCS of- ID-175 Riparian Buffers: A Livestock Best Man- fice for additional information. agement Practice for Protecting Water Quality. University of Kentucky Cooperative Extension For information about planting materials, sources of Service. Available at: http://www.ca.uky.edu/agc/ these materials, and invasive species control useful pubs/id/id175/id175.pdf. contacts include: Hill DB. 2009. FOR-112 Agroforesty: Riparian Buffer Kentucky Division of Forestry Strips. University of Kentucky Cooperative Exten- (http://forestry.ky.gov) sion Service. Available at: http://www.ca.uky.edu/ Dropseed Nursery agc/pubs/for/for112/for112.pdf. (http://www.dropseednursery.com) “Kentucky Trees.” University of Kentucky - College of Kentucky Department of Fish and Wildlife Resources Agriculture. Ed. R Geneve, R Durham, C Cassady, (http://fw.ky.gov) and T Shearin.
7 Seymour R, J Seymour, and C Blackford. 2008. Six Sweeney BW, Czapka SJ. 2004. Riparian Forest Res- Basic Elements for a Successful Native Grass and toration: Why Each Site Needs an Ecological Forb Establishment, Third Edition. Roundstone Prescription. Forest Ecology and Management Native Seed, LLC. Upton, KY. 192:361–373. Smith SR, G Lacefield, and T Keene. 2009. AGR-145 “Tree Planting Information.” 2009. Wisconsin Depart- Native Warm-Season Perennial Grasses for For- ment of Natural Resources: Forestry. Wisconsin age in Kentucky. Available at: http://www.uky.edu/ Department of Natural Resources. Available at: Ag/Forage/AGR145.pdf. http://dnr.wi.gov/forestry/nursery/GeneralInfo/ treeplanting.htm. Stange EE, Shea KL. 1998. Effects of Deer Browsing, Fabric Mats, and Tree shelters on Quercus rubra Wisconsin Department of Natural Resources and Seedlings. Restoration Ecology 6(1):29–34. University of Wisconsin Extension. 2006. Care and Handling of Bare Root Seedlings. Available at: Stringer J, W Clatterbuck, and J Seifert. 2009. Site http://dnr.wi.gov/forestry/Publications/pdf/FR-279. Preparation and Hardwood Tree Planting Guide pdf. (FOR-107). University of Kentucky Cooperative Extension Service. Available at http://www.ca.uky. edu/agc/pubs/for/for107/for107.pdf.
Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement and does not imply approval to the exclusion of other suitable products or firms.
Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, M. Scott Smith, Director, Land Grant Programs, University of Kentucky College of Agriculture, Lexington, and Kentucky State University, Frankfort. Copyright © 2010 for materials developed by University of Kentucky Cooperative Extension. This publication may be reproduced in portions or its entirety for educa- tional or nonprofit purposes only. Permitted users shall give credit to the author(s) and include this copyright notice. Publications are also available on the World Wide Web at www.ca.uky.edu.
Issued 10-2010