Wetlands

What is a wetland?

• There are three characteristics that describe a wetland:

1. Hydrology– There must be water at or near the surface of the

land for a designated amount of time.2. Soils

– Must be hydric or saturated with water to create an anaerobic (oxygen-free environment).

3. Plants – Must be “wetland plants,” meaning that they require

lots of water and the anaerobic conditions that the hydric soil creates. (Smith & Smith, 2001)

Two of the most common wetlands

Marshes• Wetlands that have lots of herbaceous plants.• Also called “wet grasslands”

Swamps• Wetlands that are forested by large trees.

Two components of hydrology

1. Physical Characteristics

– Precipitation, surface and subsurface flow, direction, chemistry, and kinetic energy of the water.

2. Hydroperiod– Duration, frequency,

depth, and flood season

Hydrology

• Basin Wetlands (lakes and ponds)– Physical: Water flow

is vertical (precipitation)

– Hydroperiod: Long with floods during periods of high rainfall.

Hydrology

• Riverine Wetlands (periodically flooded banks of rivers and streams)– Physical: Water flow is

both vertical and horizontal (precipitation and stream/river flow)

– Hydroperiod: Have short periods of flooding with stream/river flow.

Hydrology

• Fringe Wetlands (along coastal areas of large lakes and oceans)– Physical: Water flow

is both vertical and horizontal (precipitation and tidal flow)

– Hydroperiod: May be short and regular. Is not seasonal like basin wetlands.

Soils

• Soil- a mixture of mineral particles, air, water, bedrock, living and decaying organisms.

• There are literally thousands of different soils that can serve as great indicators within an ecosystem. Although each type of soil is made of three basic components, (sand, clay, and silt) they can be classified based on the amount of each.

Where do soils come from?

– Soils form as a result of bedrock being broken down into smaller particles.

• Bedrock is the igneous, metamorphic, and sedimentary rock that is in the lithosphere of the earth (the section of earth closest to the surface).– It may take hundreds or thousands of years to form

10cm of soil.– Animals, insects, and plant roots can also help break

down bedrock and introduce air into soils. • Other organic matter, such as dead organisms,

also contributes to the soil composition.

Three types of soils

1. Sandy soils– Contain mineral grains ranging from .05-

2mm in diameter.

2. Silt soils– Soils that have grains ranging

from .002-.05mm in diameter.

3. Clay soils– Contain mineral grains smaller than .002mm

in diameter.

Soil Properties

• Sandy soils– Has good drainage

and aeration– Does not store water

well– Is not suitable for most

plants

Soil Properties

• Silt Soils– Soils made from

minerals– Granule sizes are

between sandy and clay.

– Also known as “rock flour” or “stone dust” when produced by glaciers

Soil Properties

• Clay soils• Hold water very well• Do not drain water

easily• Do not have space for

air• Is not suitable for

most plants

Soil Properties

• Loam soils• Soils that contain an

equal amount of sand, silt, and clay are called Loam Soils

• The mixture of sand, clay and silt make loam soils an optimal place for plants to grow.

• Are able to hold water and air.

Soil Profiles• Soil profiles are cross-

sections of soil that extends from the surface to the bedrock. It is usually broken into layers called “horizons”.– Horizon O- Topsoil– Horizon A- Subsoil– Horizon B- Partially

weathered bedrock– Horizon C- Bedrock

Wetland Plants

• Plants in wetlands are categorized according to their ability to grow in water or hydric soils.– Obligate wetland plants

• These plants are found in wetlands 99% of the time.

– Facultative wetland plants• Usually live in wetlands (67-99%) but are sometimes found in non-

wetlands

– Facultative plants• Are found in wetlands (34-66%) and uplands

– Facultative upland plants• Usually live in non-wetlands (67-99%) but are sometimes found in

wetlands

– Obligate upland plants• These plants are found in uplands 99% of the time.

Native vs. Exotic

• If a plant is native to a particular area, then it is originally from that area (prior to European settlement).

– Native plants provide food and habitat for native animals. Without this, the native animals may be forced to migrate to areas.

– Native plants also keep local genes viable and in the gene pool.

Native vs. Exotic

• Exotic plants were not originally in the area and have been carried to the area in some way.

– Exotic plants can become invasive where they dominate the ecosystem preventing opportunities for growth for the native plants.

– Exotic plants also out grow native plants because they have no native predators.

– Invasive exotic species are the second leading cause of native species extinction (habitat loss being number one).

Why are wetlands important?

• Wetlands serve many roles in our ecosystems. A few of these roles are:– Filtering water (removes things like pollutants and

sediment)– Protect uplands from floods by temporarily storing

some of the water– Provide sources of food– Wildlife habitats– Creates healthier watersheds by removing particles

from runoff before it reaches the streams.– Prevent erosion when on banks of streams, rivers,

and lakes

What happens when wetlands are destroyed?

• Destruction of wetlands can cause many problems such as:– Increased floods– Water quality problems– Population decrease in plants and animals

that live in wetlands

Can builders destroy wetlands?• Section 401and 404 of the Clean Water

Act require developers that are going to destroy a wetland to do three things:– Avoid changing wetlands when possible– When a wetland is impossible to avoid, they

must do as little damage as possible.– If a wetland is destroyed, they must rebuild a

wetland in another place unless they pay into a special fund to restore streams and wetlands.

How can wetlands be restored?

• If a section of wetland is destroyed, environmental firms will help rebuild a wetland in another area. The U.S. Army Corps decide how much wetland must be rebuilt based on the quality of wetland that is being destroyed. Once the amount is determined, an environmental company will begin restoration by completing (but is not limited to) the following components:

How can wetlands be restored? Continued

• If developers do not pay into the fund, they must find an area to create a wetland.– This area can be a degraded existing wetland or could be an area

where a wetland would be appropriate.• They will plant vegetation that is appropriate for wetlands.• They must make sure that the hydrology is consistent with a wetland

by making sure that the system can hold water.• If hydric soils are not present, CAE will create a system where they

will develop over time. • Excavate soil• Dig a basin within a flood plain creating an area that can hold water.

Water can be retained in an area by creating dams.