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