Den Tree Characteristics and Abundance in Florida and South Carolina

Abstract

In live trees availability of dens with entrances -2.5 cm in diameter for secondary users was summarized by forest type, cover type, stand age, land ownership, stand origin, and physiographic site in Florida and South Carolina. Den density was lowest in slash pine (Pinus elliottii) and longleaf pine (P. palustris) stands and highest in oak (Quercus spp.)-tupelo (Nyssa spp.)-baldcypress (Taxodium spp.) stands. Stands ?61 years old had 3-20X more dens than 0-30-year-old stands. Soft hardwoods and oaks; particularly blackgum tupelo (N. sylvatica var. aquatica), water tupelo (N. aquatica), red maple (Acer rubrum), and laurel oak (Q. laurifolia) were prone. Dens were rare in southern yellow pines (Pinus spp.). In Florida trees were consistently larger in diameter than live trees without cavities, and most dens (70-85%) in pine, pine-hardwood, hardwood, and tropical hardwood forests were 60-year rotations are recommended to maintain 100% of potential populations of secondary users. J. WILDL. MANAGE. 50(4):584-591 Considerable attention has been given to management of forest stands in harmony with snag (dead tree) availability, but little information is available on simultaneous management of forest stands for trees (live cavitybearing trees) and timber. Den trees supplement cavities in snags and may remain standing longer than snags (Carey 1983). Up to 84% of all cavities in some forest types occur in trees that are at least partially alive (Carey 1983). Use of dens by secondary nesters is well documented. Dens in live trees should be included in estimates of availability. Specific requirements for snags and trees by secondary users have been documented for scattered geographical areas (Sanderson et al. 1976, Van Balen et al. 1982, Harlow and Guynn 1983, Huntley 1983), but timber stand improvement (TSI) in any forest stand reduces cull tree abundance and may reduce tree availability to secondary nesters. Cavity characteristics and availability vary among forest types, stand ages, and stand histories (McComb 1979, Huntley 1983, Moriarty and McComb 1983). One complicating factor in any comparisons made among published results is an inconsistent definition of cavity or den in the literature. For example, a minimum entrance diameter of 5 cm will result in an exponentially or curvilinearly higher estimate of dens/unit area than if a larger minimum entrance diameter were used. The objectives of our study were to: (1) summarize densities for each of the predominant forest types, cover types (pine, pine-hardwood, hardwood, and tropical), age classes within cover types, land ownership groups within cover types, and stand origin classes within cover types in Florida and South Carolina; (2) identify cavity-prone tree species in Florida and South Carolina; and (3) quantify entrance and height characteristics in Florida. We thank M. A. McPeek, C. E. Rowell, and the Univ. Kentucky Comput. Cent. staff who assisted with initial analyses and with logistical problems and P. L. Groetsch, W. R. Marion, T. E. O'Meara, L. A. Caine, E. D. Land, R. N. Conner, R. A. Lancia, and J. D. Gill for reviewing a draft of the manuscript. The information reported in our paper (85-8-174) was prepared in connection with Ky. Agric. Exp. Stn. Proj. 624 in cooperation with the U.S. For. Serv.; it is published with the approval of the Director.