The Everglades is often mistakenly called a swamp, but its unique characteristics distinguish it from a typical forested wetland. While some areas within the Everglades do resemble swamps, its defining feature is a vast, slow-moving sheet of water flowing across a wide, grassy plain. Understanding this distinction is important for appreciating its ecology and the ongoing efforts to protect it.
Understanding What a Swamp Is
A swamp is a type of wetland ecosystem defined primarily by its dominant vegetation: woody plants like trees and shrubs. These areas have poorly drained mineral soils and are characterized by slow-moving or stagnant water, either permanently or seasonally. Examples include cypress swamps or coastal mangrove swamps in tropical and subtropical regions. The water in swamps can be fresh, brackish, or saline, and they often form along rivers or lakes, relying on rainfall and seasonal flooding. Unlike marshes, which are dominated by grasses, swamps are treed.
The Everglades’ Defining Feature: A River of Grass
While some parts of the Everglades do contain forested wetlands, its most expansive and defining characteristic is a unique hydrological system known as “sheet flow.” This refers to a vast, shallow sheet of water that moves slowly southward across a wide, nearly flat landscape. Marjory Stoneman Douglas coined the term “River of Grass” in 1947 to describe this phenomenon, reflecting the dominance of sawgrass. Native Americans also recognized this distinct feature, calling it “Pa-hay-Okee,” meaning “grassy waters.”
The sheet flow in the Everglades is shallow, ranging from a few inches to about a meter deep, and moves at an average rate of about 34 meters (100 feet) per day. This slow movement is influenced by the slight topographic gradient from Lake Okeechobee to Florida Bay, which is less than 4.5 centimeters per kilometer. The primary vegetation in these extensive areas is sawgrass, a sedge that can grow several feet tall, forming dense stands. The presence of this pervasive sedge, rather than a dense tree canopy, is what sets the Everglades apart from a traditional swamp.
Beyond Sawgrass: A Mosaic of Habitats
The Everglades is a complex mosaic of distinct habitats. While sawgrass marshes are widespread, the ecosystem also encompasses cypress swamps, where water-tolerant cypress trees thrive in standing water. Hardwood hammocks, slightly elevated tree islands, provide drier ground and support broad-leafed trees such as mahogany and gumbo limbo.
Pine rocklands are forested areas that grow on limestone substrate and rely on fire for their ecological health. Along the coast, extensive mangrove forests flourish in brackish water where freshwater meets the sea, providing nurseries for marine life and protection from storms. Freshwater marl prairies, characterized by thin, chalky soil over limestone, and sloughs, which are deeper channels for water flow, further contribute to this diverse environment. This variety of interconnected habitats supports a diverse range of plant and animal species, many of which are found nowhere else globally.
Why This Unique Identity Matters
Understanding the Everglades as a unique, complex ecosystem, rather than merely a swamp, is important for its long-term survival. This understanding is important for effective conservation and water management. The Everglades acts as a natural filter, purifying water for millions of Floridians, and its health directly impacts regional water supply and quality.
Recognizing the hydrological needs of the “River of Grass” system, particularly the sheet flow, informs restoration projects to mimic natural water distribution and cycles. Without appropriate water flow, issues like saltwater intrusion into freshwater aquifers become more severe, threatening both ecosystems and human water sources. A comprehensive understanding fosters better-informed decisions for its protection, ensuring that this unique subtropical wetland continues to support its rich biodiversity and provide essential services.