WHAT’S A WETLAND?
WETLANDS 101
Wetlands are areas of land that are saturated with water, either permanently or seasonally, resulting in the formation of complex, extremely biodiverse ecosystems with distinct plants and animals adapted to these wet conditions.
They are often found near — but not always directly connected to — streams, lakes, and coastal inlets.
Simply put, a wetland is a combination of three main factors:
Water that is either seasonal or constantly present
Soil with a composition that retains water
Plants that can handle these water and soil conditions
TYPES OF WETLANDS
There are many types of wetlands, which can vary widely in appearance and function. They are categorized based on the distinct features and interplay of the three main ingredients listed above — water, soil, and plants.
We can determine what type of wetland we’re dealing with by answering the following questions:
-
What type of water is in
the wetland?
Freshwater, saltwater, or
a brackish mx? -
Is the water acidic
or alkaline? -
What is the primary
water source?
Precipitation, an underground spring, surface water (e.g,, streams), groundwater, or coastal tides? -
Does the wetland have
acidic or alkaline soil? -
What types of plants are growing in the wetland?
Mosses, grasses, woody
shrubs, and/or trees?
COMMON WETLAND TYPES
-
Swamps are forested wetlands with soggy soil, standing water, and woody plants like trees and shrubs.
Water type: Fresh, salt, or brackish
Water pH: Alkaline
Primary Water Source: Precipitation, groundwater, surface water, seawater
Soil pH: Alkaline
Main Plant Types: Woody shrubs and trees -
Marshes are wetlands frequently or continually inundated with water, with herbaceous vegetation.
Water type: Fresh, salt, or brackish
Water pH: Alkaline
Primary Water Source: Precipitation, groundwater, surface water, seawater
Soil pH: Alkaline
Main Plant Types: Herbaceous grasses, sedges, and rushes -
Bogs are wetlands of soft, spongy ground consisting mainly of partially decayed plant matter called peat.
Water type: Fresh
Water pH: Acidic
Primary Water Source: Precipitation — bogs are ombrotrophic
Soil pH: Acidic
Main Plant Types: Mosses, occasional woody shrubs/trees -
Fens are peaty wetlands similar to bogs, but more nutrient-rich, supporting a greater range of plants.
Water type: Fresh
Water pH: Alkaline
Primary Water Source: Groundwater, surface water
Soil pH: Alkaline
Main Plant Types: Mosses, grasses, woody shrubs/trees -
Wet Meadows are waterlogged areas dominated by herbaceous plants, found near open bodies of water.
Water type: Fresh
Water pH: Alkaline
Primary Water Source: Precipitation, surface water, groundwater
Soil pH: Alkaline
Main Plant Types: Grasses and other herbaceous plants -
Vernal Pools are seasonal wetlands that form in low areas and provide crucial, fish-free breeding habitat.
Water type: Fresh
Water pH: Alkaline
Primary Water Source: Precipitation, seasonal surface water, groundwater
Soil pH: Alkaline
Main plant types: Grass, woody shrubs/trees
THE CRUCIAL ROLE OF WETLANDS
Wetlands are vital for life on this planet. They serve as vibrant habitats, hosting a vast array of highly diverse life and fostering a complex web of interactions. Beyond the scenic beauty of these lush ecosystems, wetlands also play a pivotal role in mitigating climate change via a number of unique mechanisms.
Wetlands Are Nurseries of Life
Wetlands are often referred to as “nurseries of life” or “biological supermarkets”, because they are some of the most biodiverse and productive ecosystems on the planet—on par with tropical rainforests and coral reefs.
Annually, a single acre of wetland produces 810 tons of vegetative biomass — a fancy way of saying that wetlands grow a lot of plants. In fact, wetlands grow 2.5x more plant material than our infamously lush Pacific Northwest forests, and only produce slightly less vegetative biomass than tropical rainforests, which average 890 tons per year.
The sheer amount of plant life in wetlands supports an astronomical number of insects and microorganisms, which in turn feed the many amphibian, reptile, bird, mammal, and fish species that call wetlands home. According to the EPA, despite only accounting for 5% of the country’s land, wetlands are home to 31% of our plant species.
Wetlands provide rich habitat and vital refuge for thousands of species that live on land, in water, or a bit of both. Amphibians, fish, and many insects spawn in temporary and permanent pools. Reptiles bask on fallen trees and hide within the undergrowth. Small mammals shelter under downed logs or within the rich soil. Birds nest in the dense plant life, and rely on the surrounding waters for safety from land-faring predators.
Migratory birds especially rely on wetlands as rest stops along their journeys. Their routes are dictated by the presence of wetlands, in fact. Many of our native plants fruit in fall to take advantage of the increased bird traffic, using these winged assistants to expand their own range — an increasingly important ability in the face of rapid climate change.
The EPA estimates that over one-third of the United States’ threatened and endangered species live only in wetlands, and nearly half rely on wetlands for part of their lifecycle.
Clearly, a wetland is a nexus of biodiversity.
Wetlands Are Carbon Sinks
So why are wetlands so good at producing vegetative biomass? In short, they sequester (store) a massive amount of carbon.
Wetlands take in much more carbon than they release back into the atmosphere, creating an annual surplus that progressively increases soil fertility, enabling more and more plants and microorganisms to grow, complete their lifecycles, and ultimately add even more carbon to the soil. A wetland is both a figurative and literal carbon sink.
How are wetlands able to do this? First consider the massive amount of vegetative biomass produced by wetlands, then think about how a plant actually grows biomass.
Does it just appear out of thin air? Well, no, but actually yeah.
Plants grow by breathing in CO₂ (carbon dioxide) from the air via stomata, and using the energy they capture from sunlight via chlorophyll, they combine that CO₂ with water they’ve absorbed from the soil via roots or rhizoids to make glucose — a type of sugar. Glucose is essentially food for the plant, and in some cases a resource that can be exchanged with other organisms via symbiotic mycorrhizal relationships (more on that later).
With glucose as the driving force, the carbon from CO₂ is ultimately converted into organic carbon and used by the plant to build its biomass, creating leaves, flowers, fruits, seeds, and enabling growth in both height and width. Some of this organic carbon is also pumped directly into the soil via root exudates, which feed microorganisms. This overall process is what’s known as photosynthesis, and it creates the oxygen we breathe.
Now, where does all that carbon go when plants die? One way or another, their remains inevitably come into contact with the soil. Microorganisms like bacteria, fungi, and insects decompose the dead plant matter, further breaking down the organic compounds into their base elements, such nitrogen, phosphorus, potassium, and carbon. This is what’s known as the Soil Food Web.
During this process, some of the carbon in the plant material is released back into the atmosphere as CO₂, but most of it is transformed into more stable forms of organic carbon. Over time, some of this carbon becomes tightly bound to soil particles.
This process can effectively lock carbon in the soil for decades, centuries, or even longer! It’s estimated that soil in general stores more carbon than all the world's vegetation, and all the carbon up in the atmosphere combined, then doubled.
The hydric (waterlogged) soils found in wetlands are more efficient at storing carbon than soil found anywhere else, and they store that carbon for a longer duration than any other type of soil. This is because carbon breaks down much slower when oxygen is not present, and the hydric soil leaves no voids for oxygen to fill, resulting in anaerobic conditions.
Wetlands are estimated to store up to 10x more carbon per acre than forests, and most of that carbon is stored in the soil.
Wetlands Defend Against Climate Change
Wetlands are perhaps our best defense against the effects of climate change. They enhance climate resilience throughout the entire year — not just for nature, but also for humans, if we reintegrate them into our communities. The benefits of doing so are an absolute win-win:
Heat
Wetlands form their own beneficial microclimate; they mitigate and regulate heat due to the water and dense plant cover. If you’re familiar with the Urban Heat Island (UHI) effect, consider wetlands to be the antithesis. Wetlands are nature’s air conditioning, the OG “swamp coolers”.
In fact, wetlands are so effective at cooling the air that many cities across the world are integrating wetlands into their green spaces to protect their populations from heat-related illness and death, and for good reason. Globally, heat kills more people than all other natural disasters combined, and it’s worth noting that these deaths are massively underreported.
Fire
Wetlands are where fleeing animals, especially birds, seek refuge during wildfires. In a wildfire, a local wetland is the safest place for wildlife. The beneficial microclimate wetlands create is a powerful defense against fire. A wetland is a wildfire’s worst enemy, not only because water tends not to burn, but because when wind hits a wetland it slows down or even stops. Wetlands are natural fire breaks, where flying embers carried by the wind go to die.
Floods
Inversely, wetlands are also our best defense against floods. The EPA states that a single acre of wetland can hold as much as 1.5 million gallons of water. Wetlands are like sponges, slowing down and absorbing water into their soil. This is also how wetlands filter out water pollutants, earning the nickname “Nature’s Kidneys”.
Drought
Wetlands are able to hold all this water in place well into the dry season. It is slowly released, in the form of streams and slow-moving groundwater, recharging our aquifers and dampening drought conditions along the entire watershed throughout the year.
WETLANDS ARE VITAL FOR LIFE ON THIS PLANET
WETLANDS ARE VITAL FOR LIFE ON THIS PLANET
WETLAND WARS
Despite their benefits, wetlands have been relentlessly maligned by western society. Historically, wetlands have been viewed as wastelands, sources of disease, and obstacles to development.
During the 1800s, many believed swamps were inhospitable, useless plots of land, and the primary source of miasma — a harmful air — which was thought to cause diseases like malaria. Indigenous Traditional Ecological Knowledge (ITEK) around the importance of wetlands was ignored, and North American wetlands were systematically destroyed for decades. Countless wetlands were drained or filled in.
From the advent of European settlement, up until the mid-1980s, the contiguous United States lost 53% of its wetlands — over 104 million acres in total.
Twenty two states lost at least half of their wetlands during this time, with seven states losing over 80% of their wetlands. Ohio and California lost the most — over 90% of their wetlands were eradicated. The only contiguous state that managed to retain at least 80% of its wetlands was New Hampshire.
Percentage of Wetlands Lost in Each Contiguous State,
1780s - 1980s
Things began to look up in 1972, with the passage of the Clean Water Act (CWA), which provided significant federal protection for wetlands in the United States. The act’s watershed-based approach marked a crucial shift in environmental policy, underscoring the importance of wetlands as key players in the broader, interconnected system of American waterways. It established a comprehensive framework for water quality management and protection, and became a cornerstone of wetland conservation in the United States, helping to prevent their indiscriminate destruction and promote sustainable use.
However, In May of 2023, the United States Supreme Court rolled back these longstanding protections for wetlands. The Sackett v. EPA ruling stated that in order to qualify for the same federal protections they’d been receiving since 1972, wetlands must now be directly next to, and have a continuous surface connection with a major waterway or ocean. A large percentage of existing wetlands don’t have direct waterway connections, and some are entirely seasonal or connected to major waterways via seasonal streams.
It’s estimated that half of our remaining wetlands lost federal protection as a result of the Sackett v. EPA ruling.
Endangered US Wetlands following
Sackett vs. EPA Supreme Court Ruling (2023)
WHAT CAN WE DO FOR WETLANDS?
Though wetlands are facing numerous existential threats, there is still hope as long as people are willing to advocate on their behalf. And doing so can be as simple or complex as you wish — with enough people working toward the same goal, no action is too small.
If something you've learned here has resonated with you, pursue that thought. Share it. Go visit a local wetland. See what you see. Maybe something new will reveal itself to you. If you ever loved playing in the mud, then volunteer with your local wetland and watershed conservation groups, and enjoy knowing that there’s a scientifically measurable mental health boost as a bonus. There's likely a wetland near you, or the remnants of one that could be thriving if given even a small amount of consistent kindness. Learn how to spot your local invasive plant species, then bully them relentlessly. Plant some native wetland species. Many can be propagated by simply taking cuttings and sticking them in consistently wet soil.
There are several concrete actions you can take to help protect wetlands:
Educate and Raise Awareness: Spread knowledge about the importance of wetlands among friends, family, and communities. Awareness is key to garnering support for their conservation.
Support Wetland Conservation Organizations: Contribute to or volunteer with organizations dedicated to wetland conservation. These groups often engage in restoration projects and advocacy efforts.
Reduce Pollution: Minimize the use of fertilizers, pesticides, and other chemicals that can flow into wetlands and harm the delicate ecosystems.
Recreate Responsibly: When visiting wetlands for recreational activities like birdwatching or hiking, follow designated trails and guidelines to avoid disturbing wildlife and their habitats.
Participate in Restoration Efforts: Join local restoration projects to help rehabilitate degraded wetlands by planting native vegetation or removing invasive species.
Advocate for Policy Support: Support policies and legislation that protect wetlands and their ecosystems. Advocate for the enforcement of existing regulations aimed at preserving these critical habitats.
Advocate for Sustainable Land Use: Encourage sustainable land development practices that consider the protection and preservation of wetlands as valuable natural assets.
Monitor and Report Illegal Activities: Keep an eye out for any illegal dumping or activities that harm wetlands and report them to the appropriate authorities.
By collectively taking these steps, individuals can contribute to the preservation and restoration of wetlands, ensuring these vital ecosystems continue to thrive for future generations.