Pinhook Bog nutrient-poor. The outstanding feature of Pinhook Bog is the tree-covered mat of sphagnum moss. Sphagnum moss is a stringy, delicate moss of a light-green color. The mat floats on top of the water and can become thick, yet it can have a pocket only a few inches thick in the middle. As the mat thickens, larger and larger plants take root and grow. Under the mat a peat bed develops. The acidic water slows the decay of the sphagnum moss and other plants. With time, the peat may fill the bog from the mat to the bottom. As the moisture
Aulacomnium palustre plant communities, and individual moss species often have low cover and/or frequency. Moss species with coverages of 2% to 4% can be common to dominant in boreal communities, although ribbed bog moss attains coverages as great as 40% in some boreal communities. Ribbed bog moss grows in open and forested wetland communities. In unforested northern communities, ribbed bog moss is found in sedge ("Carex" spp.) meadows, sphagnum ("Sphagnum" spp.) peatlands, heath-sedge fens, and willow ("Salix" spp.)-dominated fens. In forests, ribbed bog moss grows in the ground layer of boreal and subboreal white spruce ("Picea glauca"), black spruce ("P. mariana"), mixed