Restoration Tools

Methods, technology, materials and theories that can be used to restore functions to wetlands

 

Tools:

•Design

•Ecological theory, including

    landscape ecology

•Control of hydrology

•Engineering

•Bio-engineering

•Earth moving

•Management of invasive species

•Horticulture

•Wildlife habitat structures

•Other structures

 

Design

•Matching each desired ecological functions with a designed feature.

•Example, sediment removal:

–Slow water by directing it over shallow floodplain.

–Vegetate floodplain with dense community of flexuous woody plants like willows.

 

Ecological Theory

•Disturbance (mowing, fire, grazing)

•Colonization

•Succession (shading, competition, dominance)

•Productivity (organic material production)

•Competition and exclusion

 

•Control?  Ecological processes can be initiated, but operate more-or-less independently.

•Intervention in the form of disturbance can be used to set back processes.

 

•Example: planting quick-growing deciduous trees to fill up ecological niche, shade out weedy grasses or shrubs, and jump forward in the successional trajectory.

 

Hydrology

•Water depth

•Flood frequency

•Flood duration

•Flood season

 

•Control?: direct

•Examples: (raising water level)

–To kill weedy emergents

•Examples: (lowering water level)

–To encourage summer annuals

–To revive over-flooded plants

–To kill aquatic weeds

–To kill trash fish

 

•Example:  Tule Lake NWR

–Wetlands serve as storage basins for excess runoff water.

–Sites are on a rotation schedule; some are drained every 5 to 15 years and used for agriculture.

–Drawdown in flooded wetlands is controlled to maximize the production of annuals whose seeds are eaten by waterfowl.

 

Engineered features

•Levees or dams

•Water control structures (valves)

•Floodways, spillways, rip-rap

•Pumps

•Conveyances (from detention ponds)

•Liners

 

•Control?  Some features (such as liners) are installed prior to operation, and continue to exert passive control.  Others, such as valves and gates, require active control.

 

 

•Example:  Liners can be high-tech, such as large membrane surfaces with heat-sealed seams.  A more economical liner might be constructed by spreading and compacting layer of clayey soil.

 

Bio-engineered features

•Brush mats

•Soft gabions

•Fascines

•Live cribbing

•Brush layering

•Live stakes, live poles

•Geo-textiles

 

•Control?  As with most biological installations, they are started on the desired trajectory, but little subsequent control is available.

 

 

•Example: Live material is often used along river banks because of the availability of good live stake material (usually willows), and because moisture conditions are often good for establishment and survival of live stakes.

 

Earth moving

•To provide adequate drainage

•Stream channels, temporary cofferdams

•Islands

•Peninsulas, protection, increased edge

•Benches (sub-aqueous, sub-aerial)

•Precise grade for flooding zones (PF, TF, PS, TS)

•Features

 

•Control?  Initial control with earthwork is difficult because precise grades are not possible in wet soils, soils may swell or erode after flooding, and sedimentation may occur.

 

•Example:  Moving earth provides depressions for storage, channels, dikes, islands, benches, and generally allows the design contours of the site to be built.

 

•Earth moving is required if a wetland has been filled and is to be returned to appropriate elevations to achieve wetland hydrology.

 

Management of invasive species

•Choosing a clean site

•Keeping a site clean before installation

•Mechanical removal

•Fire regimes

•Herbicides

•Excavation and burial

 

•Control?  An initially clean site is much easier to control for invasive species if it is quickly planted and flooded.  The “dirtier” the site, the more headaches in controlling invasives.

 

•Example: The UW Bothell site was so infested with reed canarygrass that a foot and a half of soil was excavated from 2/3 of the site, and the same depth of clean fill was placed on the other 1/3 of the site.

 

Horticulture

•Plant production

•Plant material care and storage

•Site analysis and preparation

•Installation techniques

•Vegetation maintenance

–Monitoring

–Replacement

–Invasive species plans

–Watering

 

•Control?  Horticultural control is greatest when plants are being produced and installed, and much diminished at a natural site without water or protection against weather variability, herbivory, flood damage, vandalism.

 

•Example:  At UW Bothell site, container plants were bought off-site and stored until needed.  Live stakes from salvage material on site was rooted in the nursery.

 

Creation of wildlife habitat structures

•Birdhouses, duck boxes, bat boxes

•Brush and rock habitat

•Watering stations

•Isolated areas, islands, thick brush

•Stream features (pools, riffles, logs, shading brush)

•Large wood, medium wood for invertebrates

•Perches

•Open water

 

•Control?  Initial control on installation.  A number of manufactured wildlife structures will require periodic replacement.  Brushpiles may be renewed as a by-product of maintenance.

 

•Example:  Nests for bluebirds have been installed on the Ft. Lewis prairies, and batboxes were installed at the Glacial Heritage site.

 

Construction of other structures

•Tree-throw depressions

•Rootwads

•Deflector logs in stream curves

•Large woody debris

 

•Control?  Most of these features emulate characteristics of more mature ecosystems, and so should not have to be replaced as they will eventually occur naturally.

 

 

•Example:  At UW Bothell, two stream channels were constructed; they were armored with logs and rootwads at bends.

 

•Large rootwads were anchored into the ground away from channels and artificial windthrow depressions were excavated next to them.