What on Earth is Muskeg?

Like a soggy blanket draped over the landscape, muskeg, or peat bog, covers more than 10 percent of southeast Alaska. It provides a surprisingly fragile home for an abundance of plants that thrive in the wet, acid soil. During the summer, the flowers on many of them add a carpet of soft color to the muted greens and browns typical of muskeg.

Muskeg itself consists of dead plants in various stages of decomposition, ranging from fairly intact sphagnum peat moss or sedge peat to highly decomposed muck. Pieces of wood, such as buried tree branches, roots, or whole trees, can make up 5 to 15 percent of the soil.

The water level in muskeg is usually at or near the surface. Stepping on muskeg is like stepping on a sponge, and walking across it involves avoiding the multitude of open ponds that range in size from potholes to small lakes. Despite their innocuous appearance, muskeg holes can be more than just messy - they can be dangerous. Some are quite deep and offer no toeholds to help the unwary climb back out.

Sphagnum moss is the mainstay of muskeg. It soaks up and holds 15 to 30 times its own weight in water. In the process, it keeps water from draining through the soil. So muskegs can form even on relatively steep slopes, especially in Southeast Alaska's cold wet climate.

Muskeg is so wet, acid, and infertile that about the only trees that grow in it are a few stunted shore pine (Pinus contorta). These may grow only 5 to 15 feet high and less than 10 inches around in 300 to 400 years.

Muskegs need two conditions to develop: abundant rain and cool summers. A dead plant that falls on dry soil is attacked by bacteria and fungi and quickly rots. If that plant lands in water or on saturated soil, though, it faces a diffferent fate. Air can't get to it, so the bacteria and fungi can't function well. The cool temperatures slow them down even more. All this slows decomposition, and the plant debris accumulates to form peat and eventually, a muskeg.

Updated August 25, 2000

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