SWES574's StudyStacks

Wetlands of North America (U.S. Canada and Mexico) Has always had rich and diverse wetlands • ≈ 50% of pre-European invasion wetlands have been lost. • Soggy marshes, wet meadows, salt marshes and mangroves represented inhospitable barriers to settlements and were cleared away whenever possible.

Wetland Types (applies to the whole world) Type of Wetland Area in U.S. (x 10⁶ha) Coastal • Tidal salt marshes 1.9 – mostly East Coast, Gulf Mexico • Tidal freshwater marshes 0.8 – big rivers East Coast, Gulf Mexico • Mangrove wetlands 0.5 – Florida, Texas, Louisiana Inland • Freshwater marshes 27 – over half of U.S. in Alaska • Peatlands 55 – mainly in Alaska • Freshwater swamps • Riparian systems 25 – in Southern U.S. Total 111 Overall, approximately 53% of U.S. Wetlands were lost from 1780’s – 1980’s

Mid 1970’s – strong wetland protection laws However this did not take into account “inter-conversion losses.” Instead it equates all types of wetlands to be equally valuable but this is not so.

Human activities convert millions of hectares of wetlands from one class to another. With these conversions some wetland classes increase in area at the expense of others. Swamps and forested riparian wetlands decrease while marshes, shrub wetlands and non-vegetative wetlands have and increase. Agriculture, logging, urban development and other human activities cause these conversions and overall losses.

Regional Wetlands • Peace-Athabasca Delta o Largest freshwater inland boreal delta in the world, relatively undisturbed by humans o Harbor among the last of the wild-buffalo herds o One of the most important waterfowl nesting/staging areas in N. America o Staging area for breeding ducks, geese and swans • Hudson Bay Lowlands • Prairie Potholes (primarily freshwater marshes) o Glacial depressions that seasonally fill with water o 50-75% of all N. American waterfowl come from this region o More than half lost to agriculture, half now protected • Canada’s Central and Eastern Province Wetlands o Important habitat for waterfowl o Eastern ponds, marshes and forests threatened by logging and clearing for agriculture • San Francisco Bay o ≈95 % of San Joaquin Valley wetlands gone; converted to agriculture use o Drainage contains selenium (toxic to wildlife) • Great Salt Lake • Salton Sea • Nebraska Sandhills o Largest stabilized dune field in Western Hemisphere supplied by Ogallala Aquifer. o Threatened by lowered water table from pumping for agriculture use • Great Kankakee Marsh o No longer exists due to wholesale draining for crops and pasture o Was one of the largest marsh-swamp basins in the interior U.S. • Great Black Swamp o Practically no longer in existence o Several wetlands and marshes managed for waterfowl remain • Great Dismal Swamp o Northern most “southern” swamp o Affected by human activity (draining, ditching, logging and fire) • The Pocosins o Evergreen shrub bogs on Atlantic Coastal Plain (Virginia to N. Florida) o Threatened by peat and phosphate mining • Big Rivers o Atlantic Coastal Plain, dominated by forested wetlands and marshes o Haven for ducks and geese • Okefenokee Swamp o Depression where ocean water was impounded and isolated by a sand ridge, when the water burst through it was replaced by freshwater and produced vegetated floating islands, forests and dry meadows. • Colorado River Delta • Mississippi River Delta o Where the Mississippi enters the lowlands in S.E. Louisiana o Vast wetlands prone to flooding o Elimination of wetlands produced offshore dead zone due to farm runoff • The Everglades/Big Cypress Swamp o “The river of grass”(sedge – Cladium) flows from Lake Okeechobee to Florida Bay o Encompasses 3 major wetland types  Everglades (half lost to agriculture, half now protected)  Big Cypress Swamps  Coastal mangroves

Adaptations of Wetland Plants 1. Anaerobic soils Upland soils • Made up of soil particles and some amount of air and water o 70 % soil, 15 % air, 15 % water • Plants have access to all three Wetland soils • Soils particles are submerged or saturated with water o 70 % soil, 30 % water Reduced Elements

a. Aerenchyma – air spaces in roots and stems that diffuse oxygen to the plants roots (make up 50-60% of cross sectional root volume) b. Root adaptation i. Shallow rooting ii. Adventitious roots – adaptations in most plants develop from the stem or trunk above the saturation zone iii. Prop roots – grow above the tidal level and have lenticels (holes for air entry). o Found in Rhizophora – red mangrove iv. Pneumatophores – Air roots that protrude out of the ground and exposed during low tide (have lenticels). o Found in Avicennia – black mangrove

c. Pressurized ventilation

d. Anaerobic respiration is developed in some plant

2. Salts from soils can collect

• Mostly NaCl which breaks down to Na⁺ and Cl⁻ o Na⁺ is toxic to most plants at ≈ 2,000 mg/l

• How do plants tolerate salts o The basic problem with land plants is that they use a lot of water  500 grams of H2O is transpired for every gram of dry matter produced.  The introduction of NaCl can cause a plant to contain more salt than plant and die. Salinity in Wetlands Most important salt in seawater is NaCl, second most abundant is NOSO4