Heartwood, sapwood, and fungal decay associated with red-cockaded woodpecker cavity trees

Provision of suitable sites for red-cockaded woodpecker (Picoides borealis) cavity excavation is essential for successful management of the woodpecker. To evaluate internal characteristics of pines used by the woodpecker, we increment-cored longleaf pines (Pinus palustris) to determine heartwood diameter, sapwood thickness, and presence of fungal heartwood decay at 1.3, 6.0, 9.0, and 12.0 m aboveground in 53 red-cockaded woodpecker cavity trees and 53 similar control pines in eastern Texas. Red-cockaded woodpecker cavity trees had thinner sapwood and greater heartwood diameter at all heights than did control trees (P < 0.05). Cavity and control trees were similar in height (P = 0.38) and bole length (P = 0.51), but cavity trees were larger (51.1 vs. 48.4 cm diam at breast height [dbh], P = 0.046), older (124.5 vs. 98.5 yr, P < 0.001), and were growing with less vigor (P < 0.001) than were control pines. Red-cockaded woodpeckers require approximately 15-cm diameter of heartwood in which to excavate cavities. Longleaf pines 70-90 years old had sufficient heartwood to house cavities at 6 and 9 m aboveground. Only pines exceeding 90-110 years in age had sufficient heartwood present for cavity excavation at 12 m. However, unlike prior studies, heartwood decay was not detected until trees were > 100 years and did not occur with any regularity until pines were > 120 years.