Understanding Wetland Ecosystems and Classification

Wetlands

Wetlands are characterized by standing water or inundated soil and are the only ecosystem protected by law under the Wetlands Protection Act.

Defining Characteristics

• Plants present
• Soil characteristics
• Hydrology

Wetland plants are known as hydrophytes, which possess special adaptations to live in water. While biodiversity is generally low due to a few dominant plant types, productivity is high.

Types of Wetlands

Coastal Wetlands

These are vital as nurseries for fish and invertebrates.

• Salt Marshes: Found in the Temperate Zone; herbaceous plants; primary productivity (PP) = 8000.
• Mangrove Forests: Found in the Tropic Zone; trees are dominant; PP = 3300.

Freshwater Wetlands

These are found along a gradient ranging from permanently flooded to periodically flooded.

• Freshwater Marshes: Biodiverse in bird species; herbaceous plants; PP = 1000.
• Swamps: Dominated by trees and shrubs; PP = 1200. They receive most of their water from surface runoff, are not lacking in nutrients, and have a near-neutral pH. They feature standing water in winter and spring, dry up in summer, and have considerable water storage capacity, making them very important for flood control.
• Peatlands (Bogs & Fens):
  • Fens: Grasses dominate; the rarest wetland type globally.
  • Bogs: Found in formerly glaciated regions; PP = 500; characterized by Atlantic White Cedar and Sphagnum Moss.

Sphagnum Moss

This moss causes acidic conditions in bogs (typical pH = 4). Decay occurs very slowly due to phenols and unique chemical/structural properties. Bogs receive most of their water from precipitation and have very low nutrient levels. Plants have adapted to the acidity through slow growth rates, year-round leaf retention, and the presence of carnivorous plants (e.g., Pitcher Plants, Sundews).

Wetland Delineation

Plants are categorized by their likelihood to grow in wetlands:

• OBL (Obligate Wetland): Almost always grows in wetlands (>99%).
• FACW (Facultative Wetland): Usually grows in wetlands (67–99%).
• FAC (Facultative): Equally likely to grow in upland or wetland (34–66%).
• FACU (Facultative Upland): Seldom grows in wetlands (1–33%).
• UPL (Obligate Upland): Almost never grows in wetlands (<1%).

To determine dominance, find the Basal Area (Area = πr²), total them, and divide the area by the total to find the percentage of dominance. Any plant with ≥ 50% dominance is considered the dominant plant.

Woody Plants in NE Bogs and Swamps

Found in both Bogs and Swamps: Red Maple (FAC), Speckled Alder (FACW), Highbush Blueberry (FACW), Sweet Pepperbush (FAC), Winterberry Holly (FACW).

Found mostly in Bogs: Atlantic Cedar (OBL), Leatherleaf (OBL), Sheep Laurel (FAC), Common Cranberry (OBL).

Found mostly in Swamps: Spicebush (FACW), Northern Arrowwood (FACW).

Herbaceous Plants in NE Bogs and Swamps

Found in both Bogs and Swamps: Green Arrow Arum (OBL).

Found mostly in Bogs: Sphagnum Moss (OBL), Pitcher Plant (OBL), Cottongrass (OBL).

Found mostly in Swamps: Jewelweed (FACW), Purple Loosestrife (OBL), Skunk Cabbage (OBL), Cinnamon Fern (FACW), Cattails (OBL).