Wetlands Archives | JuneauNature

Bogs, fens, wet meadows

This section treats freshwater wetlands. (Saltwater wetlands are under Habitats>Coastal>Estuaries>Salt marsh.) Ancient wetlands (bogs and fens) have deep peat. But many younger Southeast wetlands are responding to geologically recent disturbances such as glaciation or beaver activity.

Gently sloping dome bog with minimal contributing area, on bench between Kaxdigoowu Héen (Montana) and McGinnis Creeks. Average slope 8 degrees. Large pond with half-grown pond lily, crowberry abundant. ORV trail runs through this panorama. Not too much erosion here where wheels just mash down dwarf shrubs, but in more open sphagnum rutting is severe.

Poorly drained habitats, beginning on top with small-tree forests on soil too wet for optimal tree growth. Among nonforested wetland types, younger marshes or wet meadows (shallow peat) can be distinguished from ancient, deep-peat habitats called bogs or fens depending on movement of ground water.

In summer 2014, Koren Bosworth, Cathy Pohl, Andrew Allison and I surveyed wetlands throughout the CBJ. It may have been the most intensive field survey of any kind conducted on lands accessible from the CBJ road system. Although we were not involved in the official report to CBJ, I did write a 512-page illustrated ‘Supplement‘ detailing all wetland assessment units mapped and ‘scored’ according to the Paul Adamus WESPAK protocol. The introduction and some appendices to that Supplement are here. Descriptions of CBJ-defined “Map Pages”—sub-units of the CBJ, also from the Supplement—are here.

~~Muskeg~~ Throughout Southeast Alaska, the colloquial term for open, nonforested wetland is “muskeg”—a colorful but imprecise term borrowed from boreal regions, where muskeg originally defined soggy black-spruce communities on permafrost. The following descriptions apply more technically correct terms in general use by wetland ecologists across North America. Habitats lumped as muskeg in Southeast include very distinctive communities, with widely differing values for wildlife. Some of these wetlands—freshwater marshes and wet meadows—are relatively young. Others—fens (dominated by deep sedge peat) and bogs (mostly with sphagnum moss peat—are so ancient that old-growth forests seem like newcomers by comparison.

A better general term than “muskeg,” long-used by ecologists for peat-covered terrain with at least 16 inches of organic matter, is peatland. If the peatland is dominated by sphagnum moss, it is called a bog. Where lusher vegetation like sedges predominates, the peatland is called a fen. Although peatland of intermediate character is sometimes difficult to pigeonhole into the category of bog or fen, the extremes in the spectrum are easy to recognize.