How to design ecological functions into a restoration project

 

EHUF 475

 

Functions that are commonly attributed to ecosystems

 

Water quality improvement

-sediment removal

-nutrient removal

Hydrology

-flood flow attenuation

-recharge

-bank stabilization and erosion control

Habitat

-specific habitat types

-primary productivity

 

How is each function generated in a restoration project?

 

Vegetation

Shaping the land

Modifying or controlling hydrology

Using landscape ecology

Engineering

Location

Organic material

Structures

 

Sediment removal

Upland

-Similar to erosion control (discussed later)

 

Wetland or stream

-Accomplished by slowing down flowing water

         Vegetation

         Increased cross-section

         Increased tortuosity of stream path

         Increased residence time

 

Nutrient removal

Upland

        Active uptake common

        Buffer strips

         Narrow strips are effective

         Channeling defeats buffer effectiveness

 

Wetland or stream

        Denitrification

        Flushing or leaching of nitrates

        Nitrogen uptake

        Phosphorus removal requires soil contact

 

Flood-flow attenuation

Upland

-Canopy and vegetation cover important

-Depth of organic material contributes

-Forests are very effective

-Grasslands are less effective

-Hardscapes are least effective

 

Wetlands and streams

-Sinuosity

-Vegetation (woody best)

-Constrictions

-Bottom friction (many shallow channels)

-Storage capacity

 

Recharge

Upland

Requires a permeable stratum

Requires adequate time of contact

-Vegetation slows down water, creates channels into soil (may also extract water)

-Depressions

 

Wetland

In a wetland, you need

-A permeable layer

-Water source

-Adequate head

 

 

Bank stabilization and erosion control

Upland

        Control generally achieved by encouraging growth of plant material

         Canopies and duff layers minimize rainsplash erosion

         Grasses and other fibrous root plants hold soil

        Steep slopes, long slopes and coarse soils may encourage erosion.

 

Wetland

        Fast-growing, energy absorbing woody vegetation good

        In coastal wetlands, stabilization is achieved by

         Energy-absorbing vegetation

         Shallow water (frictional dissipation of energy)

         Minimal fetch

 

Primary production

Upland

        Increase of biomass and pools of resources contribute to stability of ecosystem and feed food chains.

         Cycling is efficient

         More OM results in greater conservation of nutrients, water, soil

 

Wetlands and streams

        Production encouraged by growth of vegetation along streams and by contributions of detritus to aquatic systems.

         Shallow shorelines with sunlight are very productive

         Many aquatic systems are very leaky and have flow-through of detritus, nutrients, water

 

Habitat

Upland

        General habitat may be improved by increasing plant biodiversity or structural diversity

        Specific habitat

         Bird houses, bat boxes, snags, bee boxes, brush piles, wood piles, rock piles

 

Wetland

        Wetland types are many, but you usually have little choice as to type you restore

        Wetlands often differ in plant composition from site to site

         So multiple wetlands can increase diversity

        Maximize shallow-water area

        Minimize open water

        Constructed habitat features also common

 

Streams

        Pool/riffle ratios

        In-stream wood

        Overhanging vegetation

        In-stream shelters

        Side channels