This weekend, a visitor at the Audubon Center at Francis Beidler Forest asked about pecky cypress. Although there are no examples along the boardwalk and many of the old-growth (1000+ years old) trees are hollow in the middle, there is a classic example of pecky cypress along our canoe trail. The tree was felled by Hurricane Hugo with the pecky interior exposed when the portion blocking the trail we use for tours was removed.
Image by U. S. Forest Service
The wood-decaying fungus Stereum taxodi attacks the heartwood of the Bald Cypress (Taxodium distichum) creating the long, narrow "pecky" cavities (a.k.a. brown-pocket rot). The fungus usually attacks older trees (we have 1800 acres of old-growth) from the canopy through the heartwood and down to the base, but ceases once the tree is harvested. Fungal spores enter at a point where the tree has been damaged in some way (lightning, wind, other trees falling). A cursory look at the ancient trees along the boardwalk reveals that all of the trees have experienced some form of damage. However, not all trees are attacked by the fungus and any tree that has been attacked cannot be identified until it is harvested.
The pecky cavities form from the middle of the tree outward along the tree's growth rings. Not all pecky is created equally. Pecky cavities come in small, medium, and large sizes, which will offer different textures and patterns when the wood is milled (see some images here). As long as there is sufficient wood unaffected by the fungus, the wood products will maintain their strength.
The well-drilled snag in the image is not an example of pecky cypress, but is an example of incessant pecking activity of the resident species of woodpeckers!
Image by Mark Musselman