freshwater marsh

FRESHWATER MARSHES

Wetland Ecology and Management

NATR 5250/6250

Key Terms and Concepts

  • Marsh Vegetation in Response to Hydrology: The types of plants found in marshes change depending on water levels and availability.

  • Plant Zonation: Different plants occupy different zones in marshes, influenced by hydrological factors.

  • Perennial vs. Annual Plants: Perennials live for multiple years, while annuals complete their life cycle in a single year.

  • Marsh Consumers: This includes a range of organisms from invertebrates to mammals that inhabit marshes.

  • Bird Habitat: Marshes provide essential habitats for various bird species.

  • Everglades:

    • Cattail Invasion: The intrusion of the cattail plant (Typha spp.) is impacting the biodiversity of the Everglades.

    • Invasive Species: Species that are not native and disrupt local ecosystems are affecting the local flora and fauna.

  • Fire and Hydrologic Alterations: Changes in fire regime or water levels can significantly impact marsh ecosystems.

  • South Florida Agriculture and the Everglades: Agricultural practices in South Florida have implications for the health of the Everglades.

  • Everglades Restoration Efforts: Ongoing projects aimed at restoring the ecosystem health of the Everglades.

Key Species

  • Cattail (Typha spp.): Common marsh plant that can dominate in certain conditions.

  • Bulrush (Schoenoplectus spp.): Another prevalent marsh plant often found in wetland areas.

  • Soft Rush (Juncus effusus): Species characterized by its soft, round stems.

  • Pickerelweed (Pontederia cordata): Aquatic plant that grows in shallow, slow-moving water.

  • Sawgrass (Cladium jamaicense): Iconic marsh plant of the Everglades, serves as habitat for numerous species.

  • Muskrat (Ondatra zibethicus): A common mammal found in marsh environments, known for its burrowing behavior.

Freshwater Marsh Locations

  • Freshwater Marsh in South Florida

  • Naselle River, Washington

  • Olentangy River Wetland Research Park, Ohio

Marsh Characteristics

  • Diversity: Marshes can be of varying sizes and have different vegetation types that are adapted to their specific hydrology.

  • Hydroperiods: Marshes can be classified based on their water saturation periods, being influenced by groundwater or surface water inputs.

  • Minerotrophic Nature: Marshes typically have mineral soils with lower organic matter when compared to other wetland types.

  • Non-Tidal: Unlike coastal wetlands, freshwater marshes are not affected by tidal movements.

Major Marshes of the World

  • Everglades, USA

  • Pantanal, South America

  • Prairie Pothole Region, USA and Canada

  • Okavango Delta, Botswana

  • Mesopotamian Marshlands, Iraq

  • Danube and Volga River Deltas, Eastern Europe

  • Freshwater Wetlands: Approximately 20% of the world's wetlands are classified as freshwater marshes.

Hydrology

  • Water Levels: Stability varies with geographic location; coastal marshes tend to have more consistent water levels while inland marshes experience greater variability.

  • Groundwater vs. Surface Water: The source of water greatly influences the characteristics of marshes and ecological interactions within those systems.

  • Seasonal Variations: Marshes undergo changes in hydrology throughout different seasons.

Hydroperiods of Different Freshwater Marshes

Typical Hydroperiod Patterns:

  • Natural Hydrology

  • Managed Water Levels

  • Relative depth changes as influenced by seasonal variations (wet and dry years) typical in marsh environments.

Marsh Hydrology and Biogeochemistry

  • Water Source Importance: Understanding if a marsh is fed by groundwater or surface water is critical for accurate ecological classification.

  • Recharge or Discharge Wetlands: Marshes serve as either sources or sinks for groundwater, affecting local hydrology.

  • Minerotrophic Dominance: Defined by mineral soils and a generally neutral pH, these wetlands can vary greatly in terms of nutrient availability.

Marsh Vegetation Dynamics

  • Vegetation Zones: The types and distributions of plant species in marshes are largely determined by the hydrology and topography of the area.

  • Flood Timing's Impact on Diversity: Timing and depth of inundation influence the survival and success of plant germination—annuals may be suppressed or promoted based on flooding conditions.

  • Nutrient Availability's Effect: Increased nutrient levels can sometimes lead to decreased plant diversity within marsh ecosystems.

  • Latitude's Influence on Species Composition: The plant species present in marshes may change based on latitude and regional climate.

  • Role of Fire Regimes: Regular fire can be a natural process that benefits the maintenance and health of marsh ecosystems.

Cross-Section of a Temperate Freshwater Marsh

Vegetation Zones: The cross-section includes:

  • Periodically Flooded Sedges:

    • Carex spp.

    • Arrowhead: Sagittaria spp.

  • Waterlogged or Shallow Water Areas: Including various emergent plant species such as

    • Cattail (Typha spp.)

    • Bulrush (Schoenoplectus spp.)

    • Water Lilies (Nymphaea spp.)

  • Continuous Standing Water: Supporting:

    • Lowland Grasses: Includes trees like cottonwood (Populus) and willow (Salix) at transition zones towards uplands.

Common Marsh Species in the Southeastern U.S.

Intermediate-Deep Marsh Zone

  • Cattails (Typha spp.): Predominantly found in deeper areas.

  • Bulrush (Schoenoplectus spp.): Common in variable depths.

  • Alligator Flag (Thalia geniculata): Found in wetter areas.

  • Spatterdock (Nuphar luteum): Prefers standing water conditions.

Intermediate-Shallow Marsh Zone

  • Pickerelweed (Pontederia cordata): Thrive in slightly shallower conditions.

  • Maidencane (Panicum hemitomon): Adaptable to variable water levels.

  • Arrowhead (Sagittaria lancifolia): Species fostering wetland biodiversity.

  • Soft Rush (Juncus effusus): Common in shallow water.

Experimental Results on Hydrology Impact in Marshes

Effects of Different Hydropatterns on Vegetation

  • Continuously Flooded:

    • Wetland Plant Diversity: Lowest, consisting mainly of obligate wetland perennials with few to no annuals.

    • Density Characteristics: High density of obligate species.

  • Flooded Then Moist Soil:

    • Species Diversity: Mid-range with high densities of obligate perennials.

  • Moist Soil Then Flooded:

    • Diversity: Mid-range species richness with lower densities of obligate plants.

  • Continuously Moist Soil:

    • Highest species diversity: Higher density of annuals than obligate species.

Consumers in Freshwater Marshes

Invertebrates

  • Role in Ecosystems: Many are detritivores, breaking down organic material. Common groups include:

    • Diptera: Such as midges, mosquitoes, and crane flies (both adults and larvae).

    • Crayfish and Snails: Frequently found in marsh habitats.

Birds

  • Common Bird Species: Include various waterfowl and wading birds:

    • Duck Species: Dabbling and diving types prevalent.

    • Wading Birds: Such as rails, herons, and egrets.

    • Passerines: Including Red-winged Blackbirds, Tree Swallows, Least Bittern, Canvasbacks, and Great Egrets.

Fish

  • Population Dependency: Fish communities often depend on the hydroperiod and connection to water bodies.

    • Common Species: May include common carp and various other aquatic species.

Amphibians and Reptiles

  • Wetland Taxa Importance: Amphibians and reptiles are essential components of marsh ecosystems and are often dependent on wetland habitats.

  • Example Species: Common bullfrogs and their tadpoles inhabit these environments.

Mammalian Consumers

  • Muskrat (Ondatra zibethicus): A significant mammal in marshes that modifies habitats through burrowing and foraging.

Primary Production and Decomposition in Marshes

  • Productivity: Freshwater marshes are highly productive ecosystems, often exceeding 1000 g biomass m^{-2} yr^{-1}.

  • Influencing Factors: Various factors including species diversity, local climate, hydrology, and availability of nutrients influence overall productivity.

  • Root to Shoot Ratio: Commonly observed ratios are >1 for biomass but <1 for productivity in certain species dynamics.

  • Decomposition Variability: Rates can fluctuate based on hydroperiod, nutrient quality of detritus, and climate conditions.

The Everglades Ecosystem

System Components

  • Kissimmee River: Integral to the hydrology of the Everglades.

  • Lake Okeechobee: Acts as a significant water source.

  • Big Cypress Swamp: Contributes to the overall wetland complex.

  • Florida Bay: Coastal mangrove ecosystems associated with the Everglades.

Climate Patterns

  • Subtropical Conditions:

    • Rainfall: Seasonal, with a distinct pattern including dry season (November to May) and wet season (June to September).

Sawgrass Marshes

  • Dominance of Sawgrass (Cladium jamaicense): Often the primary vegetative species in these marshes.

  • Growth Conditions: Growth varies with water and nutrient conditions; can form nearly monocultural stands.

  • Hydrological Conditions: The duration of inundation can last from 6 months to almost continuous flooding with depths reaching up to 0.5 m.

  • Fire Sensitivity: Management practices must consider sensitivity to fire and flooding which can alter marsh ecology.

Alterations to the Everglades

  • Nutrient Enrichment: Increased nutrients from agricultural runoff leading to cattail invasion.

  • Hydrological Changes: Alterations due to competing water demands and development influence water flow and quality.

  • Fragmentation of Habitat: Disruption of ecosystems due to human activity.

  • Invasive Species: Non-native plants and animals altering ecological dynamics.

  • Impact of Fires: Natural and human-induced fires have significant ecological implications.

Restoration Efforts

  • Comprehensive Everglades Restoration Plan (CERP): Aimed at restoring more natural hydrology and ecology to the Everglades system.

Everglades Agricultural Area (EAA)

  • Impact of Agriculture: The EAA is a vector for phosphorus enrichment influencing Everglades water quality.

Maps and Diagrams

Water Conservation Areas

  • Representation of water management areas critical for the conservation of the Everglades transitioning zones.

Aerial View of Stormwater Treatment Areas (STAs)

  • Critical infrastructure designed to improve water quality entering the Everglades ecosystem.