Wetlands in the perspective of global change

Wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface (Cowardin, December 1979).

Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas (Clean Water Act)

Types of wetlandsMarshes (soft-stemmed vegetation)Swamps (mostly woody plants)Bogs (freshwater wetlands, acidic, peat

deposits, evergreen trees and shrubs, sphagnum)

Fens (freshwater wetlands, fed by mineral-reach waters, neutral or alkaline, peat deposits, grassy vegetation)

North Florida saltmarshes

Formed along the edges of estuaries

Buffer against brief storm surges (protection of the shore against degradation)

Nurseries for fish, crustaceans, mollusks

Vasyugan swamp or bog (Western Siberia)

• The largest swamp in northern hemisphere (53,000 km²) formed 10,000 years ago, has been growing in size since then.

• Main source of freshwater in the region• Huge peat deposits (carbon sink)

Pantanal – tropical wetland

Wetland functions

Water storage and groundwater replenishment

Shoreline stabilityFlood controlWater filtrationBiological productivityCarbon storage (carbon sink)Methane production

Water storage and groundwater replenishment

Water is collected, stored and slowly released to aquifers or surface water

Shoreline stabilizationRoots anchor in sediment, preventing erosionVegetation diminishes the wave action

Flood control

Water filtration

Nutrient uptake (including excess from fertilizers etc.) and storage by plants

Sediment trapsBiofiltration and removal of toxic substances

by plant roots and bacteria

Biological productivityWetlands are among most productive

ecosystems in the world, comparable to tropical rainforests and coral reefs

Provide habitat to diverse species

Carbon storage

Methane production

Major global change agents influencing wetlands

Sea-level riseGlobal warmingDirect anthropogenic influence