Wetlands Study Guide

Wetlands Overview

Types of Wetlands

  • Classification Factors:

    • Varies depending on perspective.

    • Broad Categories:

    • Inland Wetlands: These are located away from coastal areas.

    • Coastal Wetlands: These are located along coastlines.

    • Geomorphological Basis:

    • Riverine Wetlands: Wetlands formed by river processes.

    • Depressional Wetlands: Distinct basins that collect water.

    • Coastal Wetlands: Created by oceanic and tidal influences.

    • Peatlands: Wetlands that accumulate peat over time.

Common Types of Wetlands in the US

Marshes

  • Description:

    • Frequently or continually inundated with water.

  • Vegetation:

    • Dominated by herbaceous (soft-stemmed) emergent vegetation adapted to saturated soil conditions.

    • Types include:

    • Tidal Salt Marshes: Located in coastal areas, influenced by tidal action.

    • Freshwater Marshes: Found inland and not saline.

  • Examples of Plant Species:

    • Smooth cordgrass (Spartina alterniflorus)

    • Saltmarsh rush (Juncus gerardii)

Swamps

  • Description:

    • Characterized by saturated soils and/or standing water.

  • Vegetation:

    • Dominated by woody plants, such as trees and shrubs.

  • Distribution:

    • Common in southeastern U.S. often associated with river floodplains.

  • Significance:

    • Serve as wildlife habitat, nutrient uptake, and can provide timber resources.

    • Examples of Tree Species:

    • Cypress (Taxodium)

    • Tupelo (Nyssa)

    • Black willow (Salix)

Bogs

  • Description:

    • Accumulate spongy peat deposits, typically have acidic waters.

  • Vegetation:

    • Covered by thick carpets of sphagnum moss and other specialized plants.

    • Examples of Plant Species:

    • Pitcher plant (Sarracenia)

  • Significance:

    • Important for carbon storage, though only covering 3% of Earth's land area but storing 1/3 of land’s carbon.

Fens

  • Description:

    • Peat-forming wetlands that received nutrients from sources other than precipitation.

    • Less acidic than bogs and possess higher nutrient levels.

  • Vegetation:

    • Higher diversity including grasses, rushes, and wildflowers.

    • Examples of Plant Species:

    • Showy lady slipper (Cypripedium reginae)

    • Bogbean (Menyanthes trifoliata)

  • Distribution:

    • Found in similar climates as bogs.

  • Significance:

    • Contributing to flood mitigation, improving water quality, and providing habitat.

Saltwater (Tidal) Marshes

  • Description:

    • Coastal wetlands that are influenced by tides.

  • Geographical Significance:

    • Georgia has the second largest amount of salt marsh in the U.S.

  • Examples of Plant Species:

    • Smooth cordgrass (Spartina alterniflorus)

    • Saltmarsh rush (Juncus gerardii)

Freshwater Marshes

  • Description:

    • Inland wetlands dominated by herbaceous emergent hydrophytes.

  • Vegetation:

    • Includes reeds, grasses, sedges, and floating aquatic plants like waterlilies and arrowhead.

  • Distribution:

    • Located along streams and boundaries of lakes or ponds.

  • Significance:

    • Provide critical wildlife habitat and nutrient uptake.

Specific Wetland Examples

Okefenokee Swamp

  • Location:

    • Georgia, notable for its rich biodiversity.

  • Environmental Significance:

    • Habitat for threatened species such as the red-cockaded woodpecker, indigo snake, and wood stork.

    • World renowned for amphibian populations, important bio-indicators for global health.

  • Size:

    • Okefenokee National Wildlife Refuge encompasses 353,981 acres.

Mangrove Swamps

  • Description:

    • Coastal wetlands dominated by halophytic (salt-tolerant) trees.

  • Distribution:

    • Found along tropical and subtropical coasts.

  • Vegetation:

    • Contains mangrove trees from 12 genera, such as Rhizophora, Avicennia, and Laguncularia.

  • Significance:

    • Play crucial roles in storm protection and serve as nurseries for various marine species.

    • Exhibit adaptations like pneumatophores (aerial roots) for gas exchange and salt excretion mechanisms on leaf undersides.

Threats to Wetlands and Global Change

  • Main Challenges:

    • Competing demands for water from human activities.

    • Conversion of wetlands to other land uses.

  • Hydrological Balance:

    • Water levels are determined by the balance of precipitation and evapotranspiration.

  • Impacts of Increased Temperatures:

    • Higher temperatures may influence rates of decomposition, affecting carbon storage and greenhouse gas emissions, particularly CO₂ and methane.

Fun Facts

  • Wetland Composition:

    • Bogs cover only 3% of Earth's land area yet store a significant proportion of carbon.

  • Cultural Significance:

    • Historical references to bogs include bog bodies like Denmark's Tollund Man and Elling Woman, dating back to ~400 BC and ~300 BC respectively, highlighting their cultural and archaeological importance.

Closing Remarks

  • Environmental Role:

    • Wetlands play critical roles in ecosystems, from providing wildlife habitats to contributing to global carbon cycling and mitigating climate change impacts.

  • Conservation Needs:

    • Protecting wetlands is vital for sustaining biodiversity, water quality, and combating ecological threats from climate change and human activity.