Welcome to the Swamp Things blog. This is not about the classic comic book character Swamp Thing, though in a future post I will pay a bit of homage to him, as I clearly ripped off borrowed the name.
I have always had both a professional and personal/recreational interest in rivers and wetlands, an interest that has only intensified since I retired from my 8-to-5 job to become a writer in my original home turf of eastern North Carolina (I raked in $407 in royalties in 2024, but that’s OK since I lucked into a great financial advisor decades ago so I don’t have to depend of social security and royalties).
As a scientist who studies swamps, some of what appears here may be directed at fellow scientists, but those posts will be clearly labelled. This blog is for “civilians” (my term for non-scientists or scientists who do not specialize in wetland geomorphology, hydrology, or ecology). If you bothered to take a look at this and got past the part about it not being about the comic book character, you are probably either a swamp-lover, swamp-curious, or among the friends and family I have brow-beaten into taking a look. But I think the lessons we can learn from swamps are important enough to be of interest beyond fellow Swamp Things, so I hope I can eventually reach a broader audience.
Common layperson’s understanding of what a swamp is—which is not wrong—is a wet area of soggy ground and/or shallow water with trees growing in it. However, this general concept of swampness encompasses a great deal of variability, from tidal mangrove swamps of the tropics to waterlogged forest patches tucked into high, cold mountains. Because “swamp” in popular lexicon is a very loose term which is sometimes applied to bogs, marshes, and miscellaneous wet patches—which is wrong—scientists often use terms such as forested wetlands. Wetlands are generally recognized to have three key properties—a hydrologic regime characterized by frequent inundation, saturation or high water tables, vegetation adapted to wetness (called hydrophytes), and soils that reflect effects of frequent saturation, such as features resulting from reducing and anaerobic conditions(1).
Forested wetlands occur in any setting that is sufficiently wet and where trees can grow. The forested wetlands I will deal with here occur in river valleys and along the margins of coastal areas in humid subtropical areas of the southeastern U.S., especially in the coastal plains of North and South Carolina, where my kayak and I roam, off and on since 1979 and consistently since 2017.
Like other Earth surface systems, the state (nature or condition and properties) of a swamp is determined by a combination of laws, place, and history. Laws are general laws or principles that are applicable regardless of place or time, such as the physical principles of flow hydraulics, or redox (reduction and oxidation) chemistry. Place refers to the local and regional environmental context, such as the geological framework, climate setting, topography, and biogeographic factors such as the range and distribution of wetland species. History is the time factor, encompassing the age or time a swamp has had to develop and evolve, the history of environmental changes such as climate, sea-level, and land use, and past disturbances such as hurricanes, floods, and fires. Thus, even two nearby swamps on, say, the Pee Dee River are going to have significant differences, but are also likely to have more similarity than, say, a Pee Dee swamp and one on the Mekong River in Asia. That’s one reason for geographically restricting the coverage here; to make the range of conditions a bit more manageable. The other is to focus on swamps I’ve actually been in.
But that still leaves plenty of variety. Just to give an idea, take Michael Schafale’s 1235-page opus, Classification of the Natural Communities of North Carolina (4th Approximation), published in 2023 by the N.C. Natural Heritage Program. This contains 27 different coastal plain riverine or estuary-connected swamp types, and doesn’t even count depressional or isolated coastal plain swamps, marshes, swamps in other regions of the state, and numerous other wetland communities and habitats.
The highest (most general) level in Schafale’s classification is the theme, one of which is the Coastal Plain Floodplains Theme. Within the theme, distinctions are made between brownwater and blackwater systems (there is also an intermediate category).
Brownwater rivers are muddy to varying extents and are so-called because they carry a significant amount of suspended sediment and are accordingly turbid and cloudy (again, to varying extents). These include the larger rivers rising in the Piedmont or mountains and flowing across the Coastal Plain such as the Roanoke, Tar-Pamlico, Cape Fear, and Pee Dee (the blackwater/brownwater distinction applies throughout the region, not just to N.C.). It also includes smaller coastal plain streams whose watersheds experience significant amounts of soil erosion, usually due to agriculture, logging, construction, etc. Blackwater streams are confined to the Coastal Plain and their watersheds are mainly forested, so there is minimal suspended sediment, and organic acids (tannins) from vegetation and organic matter give the water a dark color.
The next level of distinction is landforms. Floodplains have distinctive landforms such as natural levees, backswamps, ridges and swales, point bars, oxbow lakes, etc. These differ in elevation above river levels (and thus in their hydrologic regime) and in their soil or substrate characteristics and thus support different plant communities. In smaller streams the landforms may be too small to bother differentiating separate communities, so a single community may be identified across the entire floodplain. Finally, the dominant tree species are considered. So, for example, we have Cypress-Gum Swamp (Brownwater Subtype). These are found on brownwater river floodplains, in “very wet” forests with closed to somewhat open canopies. They are dominated by bald cypress (Taxodium distichum) tupelo gum (Nyssa spp). In this case the canopy contains water tupelo (Nyssa aquatica) which is dominant or cod0minant with cypress. Swamp tupelo (N. biflora) is rare or absent. That’s just an example of one of the 27 communities; we’ll talk more about cypress, swamp, tupelo, water tupelo, and what they tell us about swamp dynamics in a later installment.
South Carolina has an older (1986) and less detailed classification (only 64 pages), with only three types that might encompass the swamps of interest here. This classification does not separate brown and blackwater rivers, but does indicate that such separation may be warranted. (2)
There will be a bias in the blog toward geomorphology (landforms and surface processes such as deposition and erosion), hydrology, soils, and landscape-scale ecology, but I will also cover other aspects that I find interesting, which may include posts on critters (I know alligators and beavers will make it in eventually; requests or suggestions for others welcome); specific plants (other than cypress and tupelo, which will certainly appear), and perhaps even some history and anthropology.
--Jonathan Phillips, jdp@uky.edu
(1) Iron-bearing minerals are subject to oxidation (rust is one example) when exposed to both air (free O2) and water. With just water and no air (saturation), iron becomes reduced. Oxidized iron is, for all intents and purposes, insoluble, while iron in reduced forms is soluble and can be leached out of soils and sediments. Therefore saturated, reducing conditions result in the loss of iron, often indicated by grey, blue, and greenish colors (oxidized iron is reddish, orange, yellow, or light brown). Anaerobic (no O2) conditions are important primarily because they greatly slow the rate of organic matter decomposition.
(2) Nelson, J.B. 1986. The Natural Communities of South Carolina. South Carolina Wildlife and Marine Resources Department.
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