Wetland Types and Status in U.S.

Types:

Coastal Wetlands:
Inland Wetlands
-tidal salt marshes                                    -freshwater marshes
-tidal freshwater marshes                         -northern peatlands
-mangrove                                              -riparian wetlands

Amount:

Coastal
11 million hectares in the U.S.
63% are the wooded types (forests)
16% are the salt marshes: .2 million hectares, mostly dominated by Spartina
17% are freshwater marshes
Mangroves- 300,000 hectares ( too small to give a percent), will not grow about mean 20 degree C isotherm
                 - mostly in the Everglades and Mississippi Delta

Notes: steepness of land on east coast is less than on the west coast, and the tides are diurnal here. This is easier on the vegetation
        : east coast marshes can be several miles, creates bigger intertidal zone, where the marshes develop
        : on west coast, the intertidal zone is comparably smaller, not very much area for marshes to develop

Inland
32 million hectares altogether in U.S.
7 million hectares of freshwater marshes, shallow water body that is completely choked in emergent vegetation
        - ( Everglades dominated by reeds, cattails, and sedges)
10 million hectares of northern peatlands, mostly in Great Lakes area (111 million hectares in Canada)
 22.3 million heactares of southern swamps and riparian areas
       - southern swamps are deepwater swamps with trees in them, most ecologically important, but it has suffered the
         most from deforestation
       - woody wetlands dominated by Cypress (Taxodium) and Gum (Nyssa) trees
       - In Arizona, there is about 100,000 hectares of river riparian areas

Status


Review of original wetland definition: shallow water or saturated soil unique hydric soil hydrophytic vegetation

There are several fuzzy areas in this definition. 1) Variability in flooding conditions within a year, and from year to year. Similarly, fluctuating of water levels in ground water. 2) All three characteristics may not be met (i.e. boundaries of three are not the same). 3) Different kinds of wetlands may not fit criteria.

Two types of definitions can be found. 1) one is scientific - involving classification, inventory, and research 2) one for managers and regulators - (jurisdictional) control wetland modification and changes in water quality.

The wetland definition only requires that under normal circumstances vegetation is typically adapted for survival in a saturated area. This is needed for practical limitations of rapid evaluations and reasonable amounts of effort. It is not possible to wait several years to test soil saturation levels, looking at plant life is a good enough evaluation.


Table 3.3 in book
Presettlement 1700's               60-75 million hectares
1906-1987 (8 estimates)         30-40 million hectares left                 
How much has been lost? 35-50%
The best current estimate is 42 million hectares.


Map of US with Wetlands

Go over typical evolution of aquatic systems - wetlands

Concern is over conversion of wetland types:
- cutting down forested wetland trees turns to freshwater marshes
- "created" wetlands does not equal natural wetlands
              - constructed wetlands, artifical wetlands

Case Study with Joy Zedler in San Diego: studing wetlands to see if they can recreate habitats for animals
          - research shows it does not

Big Problem

-loss of hardwood swamps or river bottoms
-conversion of shrub wetlands (bushes); clearing of shrubs; conversion to freshwater marsh; conversion to farmland or   urban land
-converted immediately to agriculture land and urban land, but could become non-vegetative wetlands (ponds)
-convert farmland to non-vegetative wetland pond with government money
Example: Mississippi Marsh Land has gone from 8.5 million hectares to 2 million hectares
Note: "No Net Loss" may be misleading because there may be no loss, but significant conversion and mitigation wetlands may be insufficient or non-functioning!