Table of Contents
Wetlands represent some of the most ecologically significant and biologically diverse ecosystems across North America, serving as critical habitats that support an extraordinary array of plant and animal species while providing essential environmental services that benefit both wildlife and human communities. These transitional zones between terrestrial and aquatic environments play an indispensable role in maintaining ecosystem health, regulating water quality, mitigating climate change impacts, and supporting biodiversity on a continental scale.
Understanding Wetlands: Nature’s Most Productive Ecosystems
Wetlands are areas where water covers the soil or remains present at or near the surface for varying periods throughout the year. These unique ecosystems exist at the intersection of land and water, creating conditions that support specialized plant and animal communities adapted to saturated soil conditions. Wetlands are among the most productive and biodiverse ecosystems on Earth, with 40 percent of all plant and animal species living or breeding in wetlands.
The significance of wetlands extends far beyond their physical boundaries. These ecosystems provide life-sustaining habitat for a wide diversity of species, including at least a third of the nation’s threatened and endangered species and more than 900 North American plant and animal species. This remarkable concentration of biodiversity underscores the critical importance of wetland conservation efforts throughout the continent.
Wetlands covered less than 6 percent of the lower 48 states as of 2019, which is half the area they covered since the 1780s. This dramatic reduction in wetland acreage highlights the urgent need for enhanced protection and restoration initiatives to preserve these invaluable ecosystems for future generations.
The Ecological Importance of Wetlands in North America
Biodiversity Hotspots and Wildlife Habitat
Wetlands function as biodiversity hotspots, supporting an astonishing variety of life forms that depend on these ecosystems for survival. The unique conditions created by wetlands—including water availability, nutrient-rich soils, and diverse vegetation structures—create ideal habitats for numerous species that cannot thrive elsewhere.
Approximately half of all Endangered Species Act species in the United States are wetland dependent, demonstrating the critical role these ecosystems play in species conservation. This dependency extends across multiple taxonomic groups, from microscopic invertebrates to large mammals, each finding essential resources within wetland environments.
For avian species, wetlands serve as crucial stopover points, breeding grounds, and wintering habitats. Wetlands provide stopover and wintering habitats for more than 4 billion birds from Canada as well as breeding habitats for nearly five billion migratory birds en route to the tropics. The diverse resources provided by wetlands attract and support 43 species of ducks and geese in North America, making these ecosystems essential for waterfowl populations across the continent.
Specialized Plant Communities
Nearly 7,000 plant species live in United States wetlands, many of which can only survive in these wet environments. These specialized plant communities, known as hydrophytes, have evolved unique adaptations that allow them to thrive in water-saturated soils where most terrestrial plants cannot survive.
Wetland vegetation plays multiple ecological roles beyond providing habitat. Plants in these ecosystems help stabilize soils, filter pollutants, cycle nutrients, and produce organic matter that forms the foundation of complex food webs. The diversity of plant life in wetlands creates structural complexity that supports various wildlife species, from nesting birds to aquatic invertebrates.
Aquatic Life and Fisheries Support
Wetlands provide shelter and vital nursery habitat for many species of fish and are an important source of cultural resources for communities and many Native American Tribes. The shallow, productive waters of wetlands offer ideal conditions for fish reproduction and juvenile development, with abundant food sources and protection from predators.
Wetlands are nurseries for many salt and freshwater fishes and shellfish of commercial and recreational importance. This nursery function supports both subsistence and commercial fisheries, contributing significantly to regional economies and food security throughout North America.
Environmental Benefits and Ecosystem Services
Water Quality Improvement and Filtration
One of the most valuable ecosystem services provided by wetlands is their capacity to improve water quality through natural filtration processes. Wetlands act as natural water purifiers, filtering sediment and absorbing many pollutants in surface waters. This filtration function occurs through multiple mechanisms, including physical settling of suspended particles, chemical transformation of pollutants, and biological uptake by plants and microorganisms.
Wetlands help slow runoff, keeping excess phosphorus, nitrogen, and other harmful nutrients from entering lakes and streams. By intercepting nutrient-laden runoff from agricultural lands and urban areas, wetlands prevent eutrophication of downstream water bodies, protecting water quality for both aquatic ecosystems and human water supplies.
The water purification capacity of wetlands extends to groundwater systems as well. In some wetland systems, this cleansing function also enhances the quality of groundwater supplies, providing additional benefits for communities that rely on groundwater for drinking water.
Flood Control and Water Storage
Wetlands hold and slowly release flood water and snow melt, buffer against coastal storms, and recharge groundwater. This natural flood control function becomes increasingly important as climate change intensifies precipitation patterns and increases the frequency of extreme weather events.
By absorbing excess water during heavy rainfall or snowmelt events, wetlands reduce downstream flooding and protect communities and infrastructure from water damage. The vegetation in wetlands slows water flow, allowing more time for infiltration and reducing erosion. Coastal wetlands help to blunt the force of major storms, providing critical protection for coastal communities against hurricane storm surges and wave action.
Carbon Sequestration and Climate Regulation
Wetlands play a significant role in global carbon cycling and climate regulation. The waterlogged, anaerobic conditions in many wetlands slow the decomposition of organic matter, leading to the accumulation of carbon-rich peat deposits. This carbon storage function makes wetlands important allies in efforts to mitigate climate change.
Wetlands are highly productive and biologically diverse systems that sequester carbon, removing carbon dioxide from the atmosphere and storing it in plant biomass and soil organic matter. The carbon sequestration capacity of wetlands varies by wetland type, with peatlands being particularly effective long-term carbon sinks.
Conserving and restoring vegetated wetlands will be critical to addressing climate change and threats to biodiversity. This dual benefit—supporting biodiversity while mitigating climate change—makes wetland conservation a high-priority strategy for environmental management.
Nutrient Cycling and Productivity
A stand of cordgrass in a salt marsh can produce more plant material and store more energy per acre than any agricultural crop except cultivated sugar cane. This exceptional productivity makes wetlands crucial components of regional nutrient cycles and food webs.
Nutrients and plant material flushed from some wetland systems during storms provide essential food for plants, fish, and wildlife in estuaries and other downstream ecosystems. This export of organic matter and nutrients supports productivity in adjacent ecosystems, creating ecological connections that extend far beyond wetland boundaries.
Types of Wetlands in North America
North America hosts a diverse array of wetland types, each with distinct characteristics, hydrology, and ecological communities. There are four main kinds of wetlands: marsh, swamp, bog, and fen. Understanding these different wetland types is essential for effective conservation and management strategies.
Marshes: Herbaceous Wetlands
Marshes are defined as wetlands frequently or continually inundated with water, characterized by emergent soft-stemmed vegetation adapted to saturated soil conditions. These wetlands are dominated by herbaceous plants rather than woody vegetation, creating open, productive habitats that support diverse wildlife communities.
There are many different kinds of marshes, ranging from the prairie potholes to the Everglades, coastal to inland, freshwater to saltwater. This diversity reflects variations in water sources, salinity, hydrology, and geographic location across the continent.
Freshwater marshes typically occur along the margins of lakes and rivers, in shallow depressions, and in floodplains. Freshwater marshes are characterized by periodic or permanent shallow water, little or no peat deposition, and mineral soils, and they typically derive most of their water from surface waters, including floodwater and runoff, but do receive ground water inputs.
Coastal marshes, including tidal salt marshes, experience regular flooding from ocean tides and support salt-tolerant vegetation. Coastal wetlands include tidal salt and brackish marshes, tidal freshwater marshes and mangroves. These coastal systems provide critical habitat for numerous fish and shellfish species while protecting shorelines from erosion and storm damage.
Swamps: Forested and Shrub Wetlands
Swamps are dominated by woody vegetation, such as trees and shrubs. These forested wetlands occur in both freshwater and saltwater environments, creating structurally complex habitats that support diverse wildlife communities.
Forested swamps typically develop in floodplains and low-lying areas where water accumulates seasonally or permanently. The soil is often water logged for much of the year and covered at times by as much as a few feet of water because this type of swamp is found along slow moving streams and in floodplains.
Shrub swamps are similar to forested swamps except that shrubby vegetation such as Buttonbush, Willow, and Dogwood predominates. These shrub-dominated wetlands often occur in transitional zones between open marshes and forested swamps, or in areas where soil or hydrologic conditions favor shrub growth over tree establishment.
Mangrove swamps are a type of shrub swamp dominated by mangroves that covers vast expanses of southern Florida. These unique coastal wetlands provide critical habitat for numerous marine species and protect coastlines from storm damage and erosion.
Bogs: Acidic Peatlands
Bogs are one of North America’s most distinctive kinds of wetlands, characterized by spongy peat deposits, acidic waters and a floor covered by a thick carpet of sphagnum moss. These unique ecosystems develop in areas where decomposition rates are extremely slow, leading to the accumulation of partially decomposed plant material as peat.
Sphagnum creates bogs by holding water and creating acidic conditions, and sphagnum itself may be up to 70 percent water. The acidic, nutrient-poor conditions in bogs support specialized plant communities, including carnivorous plants that supplement their nutrient intake by capturing insects.
Bogs and fens are found extensively in the cool and moist boreal regions of the Northern Hemisphere, where evaporation is low and moisture accumulates from ample precipitation and high humidity from maritime influences. The landscapes of Canada that were once overlain by glaciers host the largest peatlands (about 1.1 million square km) in the world.
In the United States, bogs and fens are found primarily in clusters around the Great Lakes and in Maine; these peatlands usually develop in basins that were scoured out by glaciers during the Pleistocene Epoch. This glacial legacy has created ideal conditions for peatland development in northern regions of the continent.
Fens: Groundwater-Fed Peatlands
Fens are peat-forming wetlands that receive nutrients from sources other than precipitation: usually from upslope sources through drainage from surrounding mineral soils and from groundwater movement. This groundwater connection distinguishes fens from bogs and creates different chemical and biological conditions.
Fens differ from bogs because they are less acidic and have higher nutrient levels, and therefore they are able to support a much more diverse plant and animal community. The higher pH and nutrient availability in fens allows for greater species diversity compared to the harsh conditions found in bogs.
These systems are often covered by grasses, sedges, rushes and wildflowers. The herbaceous vegetation in fens creates productive habitats that support diverse invertebrate communities, which in turn provide food for birds and other wildlife.
It is important to recognize that while mining and draining these ecosystems provide resources for people, up to 10,000 years are required to form a fen naturally. This extremely slow formation rate emphasizes the irreplaceable nature of these ecosystems and the importance of their protection.
Regional Wetland Diversity Across North America
Prairie Pothole Region
In the Great Plains of North America lies the prairie pothole region which provides some of the most important wetland nesting habitat for waterfowl. This landscape of glacially-formed depressions creates a mosaic of wetlands that varies in size, depth, and permanence, supporting exceptional waterfowl productivity.
The prairie potholes of the Upper Midwest in the United States are adapted to drought as well as to herbivory by muskrats. These natural disturbances create habitat heterogeneity that supports diverse plant and animal communities adapted to dynamic environmental conditions.
Coastal Wetlands
On the east coast, you can find salt marshes that act as buffer zones from the Atlantic Ocean. These coastal wetlands provide critical ecosystem services, including storm protection, water filtration, and habitat for commercially important fish and shellfish species.
Coastal wetlands face unique challenges from sea level rise, coastal development, and saltwater intrusion. Conservation of these systems requires coordinated efforts to maintain natural sediment supplies, protect against development pressures, and allow for wetland migration as sea levels rise.
Boreal Peatlands
Much of northern North America and Eurasia, as well as the Mongolian and Tibetan Plateaus, are affected by permafrost, and these regions host vast expanses of bogs, fens, and peatlands. North America possesses some of the most extensive bog and fen regions on Earth.
These northern peatlands store enormous quantities of carbon and play a critical role in global climate regulation. As climate change causes permafrost thaw in northern regions, the fate of carbon stored in these peatlands becomes increasingly important for global carbon budgets and climate projections.
Unique Regional Wetland Types
Some wetlands have localized names unique to a region such as the prairie potholes of North America’s northern plain, pocosins, Carolina bays and baygalls of the Southeastern US. These regionally distinctive wetland types reflect local geology, climate, and hydrology, creating specialized habitats that support unique ecological communities.
Wetland Biodiversity and Species Relationships
Indicator Species and Ecosystem Health
Some wetland species like dragonflies are highly sensitive to changes in the environment, and their welfare has become an important indicator of the overall health of the ecosystems where they live and breed. These indicator species provide early warning signals of environmental degradation, allowing managers to identify and address problems before they become severe.
As populations of these indicator species decline due to habitat loss and water quality degradation, we need to take notice, as what befalls one befalls another, which increases the risk of “extinction cascades” where an initial species loss leads to a domino effect of further extinctions. This interconnectedness highlights the importance of maintaining healthy, intact wetland ecosystems.
Ongoing Species Discovery
Some 200 new species are discovered in freshwater wetlands alone each year. This remarkable rate of discovery demonstrates that wetlands continue to harbor unknown biodiversity, emphasizing the importance of protecting these ecosystems before species are lost to extinction before they are even documented by science.
Connectivity and Migration
Hundreds of millions of migrating birds rely on a network of thousands wetlands to feed and rest along their intercontinental flyways. This network of wetlands functions as a continental-scale system, with individual wetlands serving as critical stepping stones for long-distance migrants.
Over 1,000 migratory fish species rely on swimways—rivers and their associated ecosystems. The connectivity between wetlands and river systems is essential for maintaining fish populations and supporting the complex life cycles of migratory species.
Threats to Wetland Ecosystems
Historical and Ongoing Wetland Loss
More than half of the 221 million acres of wetlands that existed in the lower 48 states in the late 1700s have been destroyed. This massive loss of wetland habitat has had profound impacts on biodiversity, water quality, and ecosystem function across the continent.
Loss rates have increased by 50 percent since 2009 and without additional conservation actions taken to protect these ecosystems, wetland loss will likely continue, reducing ecosystem benefits for people and habitat for fish, wildlife and plants. This acceleration of wetland loss is particularly concerning given the critical ecosystem services these habitats provide.
Wetlands have been facing growing threats and are being lost three times faster than forests, and over the past 50 years, more than one-third of the world’s wetlands have been lost due to pollution, infill for building and agriculture, invasive species and climate change.
Climate Change Impacts
Climate change poses multiple threats to wetland ecosystems, including altered precipitation patterns, increased temperatures, sea level rise, and changes in the timing of seasonal events. These changes can affect wetland hydrology, vegetation composition, and the species that depend on these habitats.
In northern regions, permafrost thaw threatens to release vast quantities of stored carbon from peatlands, potentially creating a positive feedback loop that accelerates climate change. Coastal wetlands face inundation from sea level rise, while inland wetlands may experience changes in water availability due to altered precipitation patterns.
Development and Land Use Change
Urban and agricultural development continues to threaten wetlands across North America. Wetlands are often viewed as obstacles to development and are drained, filled, or degraded to make way for buildings, roads, and cropland. This conversion of wetlands to other land uses eliminates habitat, disrupts hydrological connections, and reduces the ecosystem services that wetlands provide.
Water Quality Degradation
Pollution from agricultural runoff, urban stormwater, and industrial discharges degrades wetland water quality and harms the species that depend on these ecosystems. Excess nutrients, sediments, pesticides, and other contaminants can overwhelm the natural filtration capacity of wetlands and create conditions that favor invasive species over native communities.
Wetland Conservation and Restoration
Policy and Regulatory Frameworks
To achieve no net loss of all wetlands, including vegetated wetlands, a strategic update is needed to America’s approach to wetland conservation. This policy goal requires coordinated efforts across federal, state, and local governments, as well as engagement with private landowners and conservation organizations.
Regulatory protections for wetlands vary across jurisdictions and have been subject to ongoing legal and political debates. Effective wetland conservation requires clear regulatory frameworks that protect wetland functions while providing flexibility for sustainable land use.
Restoration Opportunities
Wetland restoration offers opportunities to recover lost ecosystem functions and habitat. Restoration projects can range from simple hydrological modifications that restore natural water flows to complex efforts that reconstruct wetland topography, soils, and vegetation.
Successful restoration requires understanding of wetland ecology, hydrology, and the specific conditions that support target species and functions. Monitoring and adaptive management are essential components of restoration projects to ensure that desired outcomes are achieved and maintained over time.
Conservation Organizations and Partnerships
Numerous organizations work to conserve and restore wetlands across North America. These groups employ various strategies, including land acquisition, conservation easements, restoration projects, research, education, and advocacy for wetland-friendly policies.
Political collaboration across states and countries and through public-private partnerships, such as current initiatives within the prairie pothole region of the northern Great Plains (e.g., Prairie Pothole Joint Venture), is required to produce the best spatially-explicit policies to maintain species across the different classes of wildlife.
International Conservation Frameworks
The Kunming-Montreal Global Biodiversity Framework (KM-GBF) was adopted by 192 countries at CBD COP15 in December 2022, to halt and reverse biodiversity loss by 2030, and wetlands are explicitly included in Target 2 on restoration, and Target 3 on protected areas (the “30×30 target”) through wording on inland water, and coastal and marine ecosystems.
These international agreements provide frameworks for coordinated conservation action and establish targets for wetland protection and restoration at global scales. Implementation of these frameworks requires sustained commitment and resources from participating nations.
Human Benefits and Ecosystem Services
Water Supply and Quality
Some wetlands help provide clean, plentiful water supplies; for example, wetlands in Florida’s Everglades help recharge the Biscayne Aquifer, the sole source of drinking water for the Miami metropolitan area. This direct connection between wetland health and human water security demonstrates the practical importance of wetland conservation.
Recreation and Cultural Values
Many wetlands contain a diversity of plants, animals, and water features that provide beautiful places for sightseeing, hiking, fishing, hunting, boating, bird watching, and photography. These recreational opportunities contribute to human well-being, support local economies through tourism, and foster connections between people and nature.
Wetlands provide recreational opportunities such as hunting, fishing, and bird watching, enriching our lives with outdoor activities. These activities generate economic benefits while creating constituencies that support wetland conservation.
Economic Values
The ecosystem services provided by wetlands generate substantial economic value through flood damage prevention, water treatment cost savings, fisheries support, and recreational opportunities. Quantifying these economic benefits helps demonstrate the value of wetland conservation to policymakers and the public.
Natural wetlands often provide these services at lower costs than engineered alternatives. For example, wetlands that filter pollutants and store floodwaters can reduce the need for expensive water treatment facilities and flood control infrastructure.
The Future of Wetland Conservation
Addressing Knowledge Gaps
The spatial correlation between wetland coverage and species richness has tremendous spatial heterogeneity both within and between taxonomic classes. Continued research is needed to understand these complex relationships and inform conservation strategies that effectively protect biodiversity.
This finding points to the importance for region-based conservation prioritization at a multi-state ecoregional scale, such as the EPA level III ecoregion, rather than those confined only within state boundaries. Conservation planning must account for ecological rather than political boundaries to be most effective.
Climate Change Adaptation
Wetland conservation strategies must increasingly account for climate change impacts and incorporate adaptation measures. This includes protecting wetlands that can serve as climate refugia, maintaining connectivity to allow species movement in response to changing conditions, and managing for resilience in the face of environmental change.
Wetlands themselves can contribute to climate change mitigation through carbon sequestration, making their conservation a climate solution as well as a biodiversity priority. Protecting and restoring wetlands should be integrated into broader climate action strategies.
Engaging Communities and Stakeholders
Successful wetland conservation requires engagement with diverse stakeholders, including landowners, local communities, indigenous peoples, businesses, and government agencies. Building support for wetland conservation involves communicating the benefits these ecosystems provide, addressing concerns about land use restrictions, and creating opportunities for meaningful participation in conservation decisions.
Education and outreach programs can help people understand the value of wetlands and inspire action to protect these ecosystems. Connecting people with wetlands through recreational opportunities, citizen science programs, and educational experiences can build constituencies that support conservation.
Innovative Conservation Approaches
New approaches to wetland conservation are emerging, including market-based mechanisms such as wetland mitigation banking, payments for ecosystem services, and carbon markets. These tools can provide economic incentives for wetland conservation and restoration while generating funding for conservation activities.
Advances in remote sensing, modeling, and data analysis are improving our ability to map, monitor, and assess wetlands at landscape scales. These technological tools can support more effective conservation planning and help track progress toward conservation goals.
Conclusion: The Imperative of Wetland Conservation
Wetlands stand as irreplaceable components of North America’s ecological heritage, supporting extraordinary biodiversity while providing essential services that benefit both wildlife and human communities. The dramatic loss of wetlands over the past two centuries has diminished these benefits and threatens the survival of countless species that depend on these ecosystems.
The path forward requires sustained commitment to wetland conservation and restoration, supported by sound science, effective policies, adequate funding, and broad public engagement. By recognizing the true value of wetlands and taking action to protect them, we can ensure that these remarkable ecosystems continue to support biodiversity, regulate climate, purify water, and enrich human lives for generations to come.
The challenges facing wetlands are significant, but so too are the opportunities for conservation success. Through collaborative efforts that span political boundaries, engage diverse stakeholders, and employ innovative conservation strategies, we can reverse the trend of wetland loss and restore these vital ecosystems across the North American landscape. The future of wetlands—and the countless species that depend on them—depends on the choices and actions we take today.
For more information about wetland conservation, visit the U.S. Fish and Wildlife Service National Wetlands Inventory or explore resources from the Environmental Protection Agency’s wetlands program. Organizations like Ducks Unlimited and Wetlands International offer opportunities to support wetland conservation efforts, while the Ramsar Convention on Wetlands provides a framework for international cooperation on wetland conservation.