1	Improving the Effectiveness of Filter Strips and Riparian Buffers Charles J. Barden K-State Research & Extension Forester
2	The Heartland Region has had drastically changed vegetation cover and hydrology Conversion of native prairie to cropland Reduced infiltration rates from 4+”/hr to <0.3”/hr Conversion of streamside forests to cropland Reduced streambank stability and flood attenuation Heavy grazing over vast areas Channelization of streams All lead to more rapid runoff, less infiltration Subsurface drain tiles Increases baseflow, bypass soil processes
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4	Definitions Riparian Buffer An area of trees and other vegetation located adjacent to a water body, and managed to reduce the negative impact of nearby land use Filter Strip An area of perennial grasses located to intercept surface runoff before entering a defined channel.
5	Why are buffers needed?
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7	Benefits of vegetated buffers Provide separation distance beween ag activities and the stream Filters surface runoff, removing sediment, nutrients, pesticides, bacteria Nitrate removal from shallow groundwater Streambank stability, roots provide tensile strength to soil (rebar in concrete)
8	Tree roots holding a streambank
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11	Benefits of woody vegetated buffers Shading- reduces summer peak temperatures, cooler water has higher D.O. level. Gases are more soluble at lower temperatures, whereas solids (P) are less soluble. Provides OM input, leaf and twig detritus forms base of aquatic food chain Flood attenuation
12	"Flood debris caught" Flood debris caught in streamside trees
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14	How to improve these benefits Use BMP’s in the field Ensure that water flows through the filter strip, slow, sheet flow is best Keep buffer vegetation growing vigorously
15	Keep buffer vegetation vigorous Hay or burn grass strips. Fire volatilizes N into the atmosphere, reinvigorates grass stands. Design a disk strip between the grass and woody components. Leave fallow until ready to burn. Great for wildlife and protects trees from fire damage. Establish a mix of trees and shrubs, to capitalize of different rooting depths and longevity.
16	Woody Management Consider clipping shrubs or burning shrub zone after10 years to reinvigorate. Thin trees that are crowded and growing slowly Harvest mature trees, as younger trees accumulate nutrients faster. Nutrients are stored in the trunk, branch and main root system
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18	Adirondacks “Forever Wild” NYC municipal watershed Restricted timber harvesting in mid 1800’s Decades of water sampling have shown increasing stream nitrate in “protected watersheds” High rainfall N and overmature trees, not accumulating nutrients Solution- Harvest trees, regenerate new forest
19	Research Review N removal highly variable Studies vary by season, N form and concentration, buffer width and slope, vegetation age/stage, soil type and climate. Shouldn’t we expect reported N removal rates to vary? Total N and NO₃ show 45%-75% reduction Generally- a mature buffer will remove inorganic N, and release organic N.
20	Surface runoff N reduction- 12m wide buffer
21	Conclusions of KS Buffer Study The grass-shrub buffers proved effective in reducing runoff volume and concentration of pollutants. Infiltration was the major process. For smaller fields, narrow, well-vegetated buffers may be adequate (12m vs. 25m).
22	How is N removed? Uptake by actively growing plants Cool season grasses- establish more quickly, with 2 peak uptake periods Warm season grasses better for filtering sediment Trees will absorb nutrients as long as ground is not frozen. Denitrification- reduction of NO₃ to N₂ by anaerobic microbes, requires a C source and wet soils. Decomposition of high C/N ratio OM.
23	"Surface runoff-" Surface runoff- N removal is maximized by OM on the surface, and “young” rapidly growing vegetation, and slow moving water. Subsurface flow- significant N removals can occur if flow is through the root zone (uptake and denitrification)
24	Denitrification and Immobilization Process used in wood chip filled trenches installed adjacent to drain tiles in Iowa. High nitrate removal rates, but eventually carbon source will be exhausted. Vegetation continually provides new OM for these processes in root turnover and surface litter.
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26	Factors limiting buffer effectiveness Uneven field topography- resulting in concentrated flows Use terraces, in-field grass filter strips, wetlands Steep, unstable stream banks- sedimentation into streams, and collapsing of the buffer Use cedar revetments or rock veins/weirs to stabilize Heavy deer browsing preventing tree establishment Protect young trees with shelters or fencing, plant more densely
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28	"Early Kansas buffer" Early Kansas buffer planting!
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30	Crow Creek Revetment Before
31	Crow Creek Revetment After 1 Month
32	Crow Creek Revetment After 1 ½ Months
33	Crow Creek Revetment After 2 Months—Willows
34	Crow Creek Revetment After 3 Months
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36	Crow Creek- 2 years later
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38	Little Soldier-After
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42	Little Blue River Project SCC provides cost share for streambank stabilization CCRP provides cost share and rental for riparian buffer area
43	Deer damage
44	Bur oak- NE Kansas
45	Northern Red Oak Response to Coppicing and Sheltering SC KS
46	Conclusions