Below the Surface
Forested wetlands not always wet, but there are clues to follow
When identifying forested wetlands, the types of trees and plants present can offer clues. Here, skunk cabbage is visible in the springtime.
Photo courtesy of the University of Delaware.
Ralph Tiner says that many people have a preconceived notion of what a wetland looks like. "They think that it's someplace where, any time of the year you go out there, you're going to see standing water and get your feet soaking wet walking in the muck," says Tiner, the Northeast regional wetland coordinator with the U.S. Fish & Wildlife Service. However, wetlands come in many forms beyond the stereotypical swamp.
"Wetlands represent a variety of habitats, ranging from shallow-water wetlands that are wet year-round and have water lilies growing along the shores to areas that are only seasonally wet," explains Tiner. The latter type, he notes, might have a high water table during the winter and early spring, "but during the summer you might not see any water on the surface, or even find any water if you dug a hole." This often includes what are known as "forested wetlands."
In various roles, including professor and author, Tiner has helped countless people over the past decades understand and identify wetlands in all their various forms. Forested wetlands can be tricky to identify, but there is a method to do so. Some years ago (last updated in 2005), Tiner wrote "In Search of Swampland," a two-part series that is available through Amazon and other booksellers. The first part covers what wetlands are, how they function and their significance; the second is a field guide that describes in detail how to identify wetlands by plants, soils, hydrology indicators and more.
"Wetlands are not all wet at the same time, or for the same duration," says Ralph Tiner, Northeast region wetland coordinator with the U.S. Fish & Wildlife Service. "They occur across a gradient between flooded areas to areas that there is no flooding, but a high seasonal water table."
Photo courtesy of the Kentucky Department of Natural Resources.
Tiner says that identifying wetlands is not always easy: "It's about 50-50. Half the time they're pretty obvious; half the time you have to know what you're looking for." He notes that the best time to try to identify a wetland in the Northeast is winter or, if there's winter snow cover, early spring. "When it comes to identifying wetlands, we look at a variety of things," he explains. "The first thing to consider is what the landscape position is - where are you on the landscape? If you are along a water body such as a river or stream or lake - areas that may be subject to some flooding - these are areas that we would expect to find some wetlands." Wetlands could also be present in drainageways, such as where water seeps out of a slope and flows downhill.
If you're in an area that's not near a water body, consider whether you're in a low-lying spot, he advises. "If you're in an upland area and walking through the woods, you could find a depressional area," says Tiner. There may be standing water on the surface for varying periods of time, such as with a vernal pool. "Or, if you don't see water on the surface, do you see certain types of plants that are typical of wetlands?" he adds. Plant communities that might be found in a forested wetland in the Northeast include red maple, pin oaks, black gum, swamp white oak, black spruce, cottonwoods and others.
The next step is to dig a hole to see if water is present at or near the surface, less than about 1 foot deep in the springtime, says Tiner. "If it's the summer, when water tables are typically lower, then we would look for certain soil characteristics that would reflect long-term wetness," he explains. "Examples would be gray-colored soils or a thick organic layer, anywhere from a few inches to a few feet." Tiner also makes the point that wetlands are not always found in low-lying areas. "They can be at the top of a mountain, if you have a depression and the right soil formations," he states.
So, how likely is it that someone who owns a 50 or 100-acre woodlot in New England has a forested wetland on their property? "It's quite likely," says Tiner. Beyond firsthand exploration looking for the clues already described, Tiner says there are a number of sources of information that can be consulted to help identify these wetlands. First, there are wetland maps produced by the U.S. Fish & Wildlife Service as part of the National Wetland Inventory program (www.fws.gov/wetlands), which includes a "Wetlands Mapper" feature. "You can also look at soil maps from the U.S. Department of Agriculture [http://websoilsurvey.nrcs.usda.gov]," he notes. These maps will indicate whether the soils present are "hydric," defined by the USDA as "those soils that are sufficiently wet in the upper part to develop anaerobic conditions during the growing season." These online sources "can give landowners a pretty good idea of where wetlands might be on their property," says Tiner.
The next logical question is: If I find a forested wetland on my woodlot, what do I do about it? "The first thing is to talk with your state or regional forester to ask them what you can do legally without a permit, and also what you can do with a permit," Tiner advises. "For example, if you wanted to build a road through a swamp to get access to timber, you might need a permit. And that permit might come from a state regulatory agency or the federal government. In some cases, like in Massachusetts, you might even need something from the local town."
Federal law covers all wetlands, and state law can't specify anything less than the federal law, Tiner explains. However, local and state governments can add more restrictive requirements, so it's important to consider all three levels of government - local, state and federal - when it comes to working in or around forested wetlands.
"Forestry divisions in most, if not all, states should have best management practices for dealing with wetlands," says Tiner. "As a forest owner, I would want to be familiar with these best management practices that the state has developed." And for any harvest or forest management activity, that includes using a qualified logger who not only understands these best management practices, but also has the experience and credentials to put them into practice.
"Even on my own property, I had a logging plan that called for avoiding wetlands. But when the logger got out there, he actually ran his equipment through a small wetland. It was only a few feet wide, but he was supposed to avoid that area," says Tiner. Having a plan is only the first step; that plan also has to be followed, he emphasizes.
"Treed wetlands are recognized wetlands under our state law," states Mary Ann Tilton with the Wetlands Bureau of the New Hampshire Department of Environmental Services. She says that three parameters, as dictated by the Army Corps of Engineers, are used to determine if there is a "jurisdictional wetland" on a particular site: wetland plants, hydric soils or evidence of hydrology. "Or if there's a stream that runs through the property; many times there are streams running through forested wetlands," Tilton adds.
If a forested wetland is present, New Hampshire, like many states, has a series of best management practices (BMPs) that must be followed. "Many times woodlot owners will retain a forester to file what's called an 'Intent to Cut' form; for a minimum-impact forestry project, they would have to file a separate form," she explains. "Basically, they would have to indicate what type of wetland they are crossing, what type of stream crossing they are going to be putting in - a culvert or bridge or corduroy crossing."
Tilton says that New Hampshire and other states conduct trainings for loggers on these BMPs. "The level of trainings has improved, and I believe the level of knowledge of the loggers has improved, and I think you can see that," she points out. "There's always room for improvement, but great progress has been made."
Similarly, Tilton says that in the 20 years she's been working in this field, there's been an evolution in the public's understanding of the value of wetlands. "I think years ago the level of understanding was much less. Wetlands was a fairly new science back then," she says. "I think people are much more aware today. There's a lot of outreach that's been done, and you see it in the news media."
Tilton says that outreach campaigns continue in order to share the importance of wetlands. "They provide important wildlife habitat; they provide flood abatement; they provide groundwater recharge areas; they provide water quality improvement areas; they have economic importance for wood production; they provide nutrient attenuation; and they provide a variety of sociocultural values," she states.
As part of ongoing scientific and education efforts, the UNH Cooperative Extension recently introduced an updated "NH Method" (www.nhmethod.org) for "inventorying and evaluating freshwater wetlands in New Hampshire" and providing "communities, conservation groups and natural resources consultants [with] a practical method for evaluating wetland functions." Workshops are also conducted in this state and others to provide greater information on plant communities associated with wetlands and about the different types of wetlands that might be present on a site.
For those wanting to learn more about forested wetlands in the Northeast, Tilton recommends a mid-1990s publication called "Ecology of Red Maple Swamps" (www.nwrc.usgs.gov/techrpt/93-12.pdf). The document begins with the simple statement: "Forested wetland is the most abundant class of wetland throughout the Northeastern United States."
They may not be as obvious as the stereotypical marshland, but forested wetlands are abundant and a valuable resource that just may be present in your woodlot.
Patrick White is a freelance writer based in Middlesex, Vt. Over the past 10 years, he has covered a wide range of agricultural operations around the Northeast. He is always on the lookout for unusual stories.