PP4: Wetlands

How did people used to view wetlands

During settlement of the U.S., wetlands were considered “bug-infected, disease ridden wastelands that impeded settlement and economic development” 

Policies/regulations

• Have changed over time dramatically. We view wetlands in a more positive light now  

• Most of our land has tiles underground to help to flow of water and to prevent flooding of farmland 

Wetland losses in the 80’s

Not much data on wetland loss now, but there hasn’t been a net gain of wetlands, if anything its a net loss 

estimated rate of wetland loss

• The rate of wetland loss was higher in the 50-70s  

• In the 80s we see the rate really decline  

To a federal policy of “no net loss” of wetlands, including subsidy and technical assistance to restore and create wetlands  

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Acres of wetlands

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Extent of wetlands in the lower 48 dtates

• There are many different types of wetlands 

• Costal wetlands have experienced the least amount of loss, inland forested wetlands have experienced the most 

People now view wetlands in a more positive light

• The public, especially user groups, began to recognize the resource values of wetlands 

• Concern began to grow in the 1950’s and 1960’s over an alarming rate of wetland loss in the U.S. 

• Consequently, appreciation of wetlands increased  

More recent programs and legislation provide indirect protection and incentives to conserve and restore wetlands:  

• Section 404 of the Clean Water Act 

• No net loss policies (executive orders) 

• Conservation provisions of the Farm Bills (Food Security Acts) 

• Costal Zone Management Act 

• N. American Wetlands Conservation Act 

Wetlands: Kashian definition

periodically or permeated flooded by surface or ground water. They have to support some kind of vegetation that has adapted to saturated soil

Wetlands: general definition

-wetlands include emergent macrophyte (if it comes out of the water its a macrophyte)-dominated portions of lake fringing communities (including small lakes and protected embayments of large lakes), as well as marshy areas associated with streams, and marshes, bogs, swamps, fens, and flooded woodlands  

• Difficult to define 

• Hydric soils= soils saturated with water  

• Typically anaerobic activity (low oxygen) 

• If you’re saturated, you’re normally low oxygen  

Wetlands: technical definition

• National classification system (USFWS 1977): “land where the water table is at, near, or above the land surface long enough to promote formation of hydric soils or to support the growth of hydrophytes” 

• Gosselink and Turner: “areas flooded frequently enough so that roots of emergent vegetation exist in an anaerobic environment” 

-They used to be seen as a transition state. Now we know they’re their own thing  

History: wetland science emerged as a subdiscipline of ecology in the late 1970s 

• Conservation groups became concerned over wetlands losses 

• Public began to appreciate the unique ecological functions and social values that wetlands provide 

• Driven by policy debate, managers needed a scientifically-based definition and criteria to delineate and classify wetlands  

The issues of wetlands definition and delineation illustrates the interplay of science, public policy, and values 

• Liberal, strictly scientifically-based definition provides maximal protection of wetlands, but with social, economic, and political costs  

• USFWS definition describes the unique conditions under which wetlands preform ecological functions that humans value  

• More restrictive definition preserves individual property rights, allows more flexibility to accommodate social and economic pressures, but at the cost of certain ecological services and resource values that are not accounted for in our economic system  

Connection of wetlands to other systems

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How do we define (delineate) wetlands?  

-Wetland scientists provide the answer (3 legged stool) 

• Hydrology 

• Hydric soils  

• Hydrophytes 

  • Plants that can handle the low oxygen of the soil because the soil is always saturated 

Hydrology criterion

Lands that are inundated or saturated to within 18’’ of the soil surface for > 7 consecutive days during the growing season 

Hydric soil criterion

Soils, recognizable by their color, physical structure, and chemical characteristics, that have developed under anoxic conditions associated with saturation or inundation by water 

Hydrophytic vegetation criterion

Lands that support a preponderance (more plants than not) of plants that are adapted to growing under conditions of substrate inundation or saturation 

The devil is in the details: specific criteria to satisfy different purposes 

-Scientific definition (USFWS) 

• Serves an heuristic purpose 

• Objectively broad  

• One or more criteria must be present  

• Generally liberal  

• Parameters tied to function (e.g. 7 days inundation) 

-Regulatory definition (USACE) 

• Serves social, political, or economic purposes 

• Subjectively narrowed 

• All three criteria must be present  

• More restrictive parameters (e.g. 21 days inundation) 

target/meijer ponds

People will put ponds in target or meijer parking lots if they destroy a natural wetland because then TECHINICALLY there is no net loss 

what happens when a soil is saturated or inundated 

• Water acts as a barrier to diffusion of O2 into pore space from atmosphere 

• Aerobic respiration by soil organisms depletes O2 within 7 days when the temperature is above biological zero 

Respiration continues via alternative pathways in which soil microbes oxidize organic matter by using a sequence of different molecules as electron acceptors  

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What happens to terrestrial plants and animals?  

• Macrophytes and metazoan animals respire aerobically (O2 is final e- acceptor in respiration) 

• Reduced compounds are generally more toxic than oxidized compounds 

• So lack of O2 is a stressor that wetland-dependent species must be adapted to 

Some adaptions of wetlands-dependent species: plants

• Rigid, highly vascularized stems  

• Active diffusion of O2 to roots 

• Carbohydrate storage 

• Alternative metabolic pathways  

• Reproductive strategies- seed dispersal, germination, and growth requirements  

Some adaptions of wetlands-dependent species: animals

• Morphology-locomotion in water  

• Morphology-feeding in water 

• Anaerobic respiration (driving reflex) 

• Seasonal movement and/or aestivation strategies 

• Reproductive strategies- oviposition and development and care of young  

Wetlands dogma  

-Wetlands are among the most productive ecosystems in the world 

• Some types of wetlands are NOT very productive 

-Wetlands act as “sponges” on the landscape 

• Can hold rainwater and help prevent flooding 

-Wetlands are the “kidneys” of the landscape 

• Chemical contaminants will some into the wetlands, and the carbon there will hold onto the toxicity, and the water will come out clean  

-Wetlands are hotspots of biodiversity 

Wetland functions depend on the location of the wetland within a watershed 

• Isolated wetlands are the “sponges” and “kidneys”  

• Lake margin wetlands are kinda a transition region  

Purported ecological functions and values of wetlands: hydrology

discharge and recharge groundwater, regulate surface water flows and sedimentation 

Purported ecological functions and values of wetlands: nutrient cycling

transform or sequester nutrients and chemical contaminants 

Purported ecological functions and values of wetlands: habitat

support biological diversity, recreation

Purported ecological functions and values of wetlands: habitat: trophic support

provide food and fiber products

wetland values/functions

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Hydrology functions: regulation of surface water flow and sedimentation 

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Water Quality Functions: biogeochemical cycling  

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Habitat and trophic support functions  

• Wetlands are detrital-based systems 

• ! Know this 

• Decaying plant matter supports invertebrates that are utilized by consumers

biodiversity scores

Center of a lake/ocean, biodiversity is very low, fish are the obvious exception for this, not a lot of fish by the dirt  

Total economic value of wetlands  

helpful since most people are driven by money

wetland functions

• Habitat: nesting, spawning, rearing and resting sites for aquatic and land species, food chain production 

• Hydrology: protection of other areas from wave action and erosion, storage areas for storm water and flood water, ground and surface water aquifer recharge 

• Water quality: water quality protection, water filtration and purification, treatment of nonpoint source runoff  

Types of Aquatic systems: Wetlands 

• Water table is at surface or within 1m of surface 

• Vegetation and soils similar to submersed, littoral areas 

• Can be lentic, lotic, fresh, or saline  

• Swamps (contain shrubs and trees, woody plants), marshes (contain grasses, no trees), bogs (dominated by mosses) 

• ! Know these differences  

• Are among the most productive biological systems on earth  

Wetlands: controlled by soil type, climate, source and rate of water input  

• Open, high energy systems: with significant flow-through of surface water (usually contiguous with lake or stream) 

• Closed, low energy systems with little or no surface flow  

Major freshwater wetland types: northern wetlands

Bogs and peatlands (organic-filled kettle lakes), permanent  

Major freshwater wetland types: deepwater swamp

Continually filled, SE United States 

Major freshwater wetland types: riparian (means river)

Adjacent to rivers (floodplain areas), high water table, seasonal 

Major freshwater wetland types: swamps

(hardwood and shrub swamps), unlike marshes, are dominated by woody shrubs and trees  

Major freshwater wetland types: bogs

peatlands, usually lacking an overlying layer of mineral soils 

Major freshwater wetland types: vernal pools

Are, literally, spring pools that tend to fill up in spring and dry up in summer. Biological activity peaks in spring 

Major freshwater wetland types: forested floodplain wetlands

Develop along larger rivers 

Major freshwater wetland types: prairie potholes

Are shallow depressions scattered across the upper Midwest and the Dakotas that were carved out by retreating glaciers some 10,000 years ago  

wetland designation

• Both scientific and legal definitions vary greatly 

• Of concern because of high value of drained wetlands to agriculture and urban development (S) 

  • When you drain a wetland, that soil is very nice 

• Still unclear  

Example of National Wetland inventory (NWI) Map 

the U.S. Fish and Wildlife service’s national wetland inventory (NWI) uses what is called the Cowardin classification to classify wetlands. This classification system is used by scientists and resource managers nationwide. This complex system can be difficult for the average user to interpret  

Wetland values  

• maintain biodiversity 

• Provide habitat for animals 

• Maintain water quality 

• Support commercial fishing, forestry  

• Nutrient uptake from watershed  

• Nitrogen compounds converted to N gas 

  • Play a huge role in the matinance of our atmosphere  

• Reduce flood damage  

• Hiking, fishing, hunting, bird watching, boating  

• Aesthetic value 

• Carbon sequestered into plants  

• support hydrophytes (plants that are adapted to living in wet, saturated, low-oxygen soils)  

General importance  

-A wetland is an “ecotone” between terrestrial and aquatic ecosystems, which functions in  

• Habitat for organisms from both primary ecosystems  

• Alteration of material transport to the water, often including a nutrient sink by uptake in the vegetation (although there are limits to this that can be overwhelmed by excessive inputs) 

• Water regulation- as in a sponge, the wetland soil and vegetation matrix holds large quantities of water and retards rapid surface flow-through

Why are they threatened?  

-Wet soil is not perceived as readily useful to humans  

-Drained for agriculture- then its super useful  

-Fluvial wetlands (river floodplains) 

-Drained for urban development (part of Boston was a wetland area; Netherlands was diked) 

-Loss varies by region  

• Iraq (Tigris and Euphrates Rivers)- drained in 1990s as punishment to indigenous people  

• US (drained “black swamp” coastal wetlands of great lakes of indiana and ohio 1800s) 

  • Illinois- 85% of wetlands drained  

  • Indiana- 87% lost  

  • Ohio- 90% lost 

Mitigation techniques: replacement

• If you get rid of a wetland, you can just replace it  

• Obviously not the same as the original wetland  

Mitigation techniques: reclamation

• Trying to bring an established wetland back 

• Has greater success than replacement  

How wetlands work pic

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