Wetlands: Methods and Issues of Protection
It is estimated that 53% of the wetlands in the continental U.S. have been lost since the late 1700's. Between the 1950's and the 70's we lost about 8.5% with palustrine wetlands being the hardest hit. After the mid 70's, inland freshwater marshes sustained no additional losses but we continued to lose forested wetlands at a rate of 5% annually and estuarine intertidal wetlands at about 1.7% annually.
(from: Mitsch and Gosselink, 1993)
In the mid 70's, in association with the Clean Water Act, we started making efforts to protect wetlands---why?
We finally recognized that wetlands provide many services and commodities of value to us, aside from their intrinsic value. You can consider wetland values from 3 hierarchical levels: population, ecosystem, and regional and global.
1. Population Values
a. Animals Harvested for Pelts
Alligators, beavers, muskrats, minks, and nutria are all harvested for their pelts. All of these animals depend upon wetlands.
b. Waterfowl and Other Birds
80% of America's breeding bird population and more than 50% of the 800 species of protected migratory birds rely on wetlands. Besides the value the birds may have esthetically or from an ecosystem standpoint, this supports a large and valuable recreational hunting industry ($58 million annually in Mississippi, for example). Since different groups of ducks and geese have different habitat preferences, a broad diversity of wetland types is important. For example, the freshwater prairie potholes of North America are the primary breeding place for waterfowl. It is estimated that 50-80% of the continents major game birds are produced in these wetlands. We've lost more than half of our prairie potholes and that is suggested as a major factor in the decline of nesting success of game birds.
(from: Mitsch and Gosselink, 1993)
c. Fish and Shellfish
Over 95% of the fish and shellfish species harvested commercially in the US are wetland-dependant. In addition, many freshwater fish also depend on wetlands and while they are not often commercially fished, recreational fishermen tend to spend much more per fish caught than commercial fishermen (licenses, gear, boats, travel, etc.) and all that goes into local economies.
d. Timber and Other Vegetation Harvest
The US has about 55 million acres of wetland timber. By using sound silviculture practices logging can coexist with wetlands, although many are simply clearcut and drained. Herbaceous vegetation is also a potentially useful source of energy (peat, for example) or fiber, although it's not used much in the US. The plants can also be fermented to produce methane or used for wastewater treatment.
e. Endangered and Threatened Species
Wetland habitats are necessary for the survival of a disproportionately high percentage of endangered and threatened species. Although wetlands occupy only about 3.5% of the land area in the continental US, about half the animals alone listed as endangered depend of wetlands. In 1989 there were 63 species of plants and 34 species of animals considered endangered, threatened, or candidates for listing that occupied southern US forested wetlands.
(from: Mitsch and Gosselink, 1993)
2. Ecosystem Values
a. Flood Mitigation
Wetlands influence the regional patterns of water flow. They intercept storm run-off and store storm waters, thus changing sharp runoff peaks to slower, lower discharges over longer periods of time. In this way flooding is reduced. Riverine wetlands are especially good at this but we tend not to value the service. Bottomland hardwood forests along the Mississippi River before the 1700's could store the floodwater equivalent of 60 days of river discharge. Now it's about 12 days because of draining of the floodplain leveeing (attempting to contain) the river. As we all saw a few summers ago, this creates major flooding problems for the cities and towns along the river.
(from: Mitsch and Gosselink, 1993)
b. Storm Abatement
Coastal wetlands absorb a great deal of the energy from ocean storms, thus protecting inland development. Building in these areas results in the public having to pay much of the cost of repairs to public services, as well as homes through federal insurance programs.
c. Aquifer Recharge
While soils under a lot of wetlands are impermeable, around the edges water does soak in and down to aquifers. This has not been well studied but it is assumed to have an important role in allowing this to happen. The more "edge" there is relative to the size of the wetland, i.e. the smaller the wetland, the more relatively important they are in this. Of course, it's the small wetlands that are the first to fall to development pressure.
d. Water Quality
Wetlands can remove organic and inorganic nutrients and toxic materials from water that flows across them. Wetlands have several attributes that allow them to exert considerable influence on chemicals:
i. The reduction in water velocity as streams enter wetlands causes sediments and chemicals stuck to them to drop out of the water column.
ii. A variety of anaerobic and aerobic processes are close together promoting denitrification, chemical precipitation, and other chemical reactions that remove chemicals from water.
iii. The high rate of productivity of many wetlands can lead to high rates of mineral uptake by vegetation and subsequent burial in sediments when plants die.
iv. There are diverse decomposers and decomposition processes in wetland sediments.
v. The high amount of contact between water with sediments (because the water is shallow) leads to significant sediment-water exchange.
vi. The accumulation of organic peat in many wetlands causes the permanent burial of chemicals.
e. Aesthetic Values
This is a value difficult to capture but it simply means that people enjoy wetlands. They make good natural laboratories, subjects for painting and photography, recreational sites, etc.
3. Regional and Global Values
a. Nitrogen Cycle
Ecologically useful nitrogen comes from the fixation of atmospheric nitrogen gas by a small group of plants and microbes. The current production of ammonia from nitrogen for fertilizers is about equal to all natural fixation. Wetlands may be key in returning this "excess" nitrogen to the atmosphere because that process requires an aerobic and anaerobic environment to be close together. Since most temperate wetlands receive agricultural runoff, they are likely to be important in this process of keeping excess nitrogen out of the environment.
b. Sulfur Cycle
The atmospheric load of sulfur has been greatly increased by the burning of fossil fuels (coal, gas, oil). This has resulted in acid rain, but when acid rain falls on a wetland, the sulfur is reduced to sulfide which mostly forms insoluble complexes more or less permanently removed from the sulfur cycle.
c. Carbon Cycle
Carbon dioxide in the atmosphere is steadily increasing, also due to the burning of fossil fuels and because of the rapid clear cutting of tropical rainforests (all those plants take up a lot of carbon dioxide). The burning of peat also releases large amounts of carbon dioxide. Methane released when wetlands are disturbed is also a significant source or carbon. Wetlands generally, due to high productivity, can store a great deal of carbon though. Therefore, as wetlands are increasingly disturbed, increasingly more carbon is released and less is stored.
Quantifying Wetland Values
A number of efforts have been made to quantify the "free services" and amenities that wetlands provide. For activities requiring an environmental impact statement, you must determine ecological value as compared to other sites, as well as economic value of leaving the wetland alone compared to the economic value of the proposed activity affecting the wetland. There are several problems:
1. Wetlands are multiple-value systems. They may be valuable for different reasons. For instance, a freshwater marsh may be very important for waterfowl, while a saltwater marsh is critical for fish. Which one is more valuable? Or how does that value for fish stack up against value for, say, parking?
2. The most valuable products of wetlands are public amenities that have no commercial value for the private landowner. If you own a saltmarsh, you don't benefit from the the harvest of ocean fish that once depended on your marsh. You would benefit more if you drain it and sell the real estate.
3. There is not always a clear relationship between the size of a wetland and its value. In economics, the scarcer a thing becomes, the more valuable. Below a certain size though, a wetland is useless for, say, big mammals. A wetland's value depends on its interactions with the surrounding. For example a small wetland might not be critical most of the time, but during bird migrations, it might be absolutely essential toward maintaining the bird population.
4. Commercial values are finite whereas wetlands provide values in perpetuity. Once a wetland is developed, it is often gone for good.
5. A comparison of economic short term gains with wetland value in the long term is often not appropriate. Wetland values can't "compete" with short term economic gains because rarely are future amenities considered.
6. Estimates of values depend biases of individuals and society. Certainly a wetland scientist will place a higher value on a wetland than a developer would. How do you evaluate these things objectively?
Federal Government Policies and Laws
Two important points:
1. There is no specific national wetland law.
Any protection comes from the application of laws intended for something else (like the Clean Water Act). These are spread out among many federal agencies and since the policies of each agency constantly change, for this to work would require good interagency coordination--so it doesn't generally work.
2. Wetlands are managed under regulations related to land use and water quality, when they aren't quite land or water.
The Clean Water Act, Section 404 says: "As environmentally vital areas, [wetlands] constitute a productive and valuable resource, the unnecessary alteration or destruction of which should be discouraged as contrary to the public interest." (Federal Register, July 25, 1977)
You can see where this does not do much to protect wetlands legally!
The "Takings" Issue
One of the dilemmas of protecting wetlands occurs because wetlands have values to the public at large, but rarely to the individual who happens to have a wetland on his or her property. South Carolina has been at the forefront of this issue. In Lucas vs. S.C. in 1992, the US Supreme Court ruled that regulations denying "economically viable use of land" require compensation to the individual landowner, no matter how great the public interest served by the regulations--i.e. land just can't be "taken." The case has been referred back to S.C. to determine if the developer, Lucas, was denied all economically viable use of his beachfront property that had been rezoned in response to the Coastal Zone Management Act. As far as I know, this has not yet been resolved and the "takings" issue comes up in the legislature frequently. Do you have the right to do whatever you want with your property regardless of the consequences for the public? Do you not have that right, but should you be compensated somehow for not doing what you want? This is a very complicated issue and how it ends up getting resolved could have significant implications for regulation of wetlands and private property.
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