Prescribed fire affects eastern white pine recruitment and survival on eastern Kentucky ridgetops

Successful fire prevention and suppression efforts during the past 50 yr have resulted in the proliferation of eastern white pine (Pinus strobus L.) in the understory of oak-pine forests on the Cumberland Plateau. Along with red maple (Acer rubrum L.), increasing density of eastern white pine in these forests signals a change in plant species composition from species adapted to periodic surface fires, such as oaks (Quercus spp.) and yellow pines (P. echinata Miller and P. rigida Miller), to species adapted to longer fire-free intervals. In the Daniel Boone National Forest (DBNF) in eastern Kentucky, the USDA Forest Service has reintroduced fire to these ridgetop ecosystems. In March 1995 and March 1996, single prescribed fires were conducted on three different ridgetops in the Red River Gorge of the DBNF. Diameter and age of white pine stems were recorded prior to burning, two growing seasons post-burn (for 1995 and 1996 fires), and three growing seasons post-burn (for 1995 fires only). Nearly all white pine less than 2.0 cm dbh were killed after a single prescribed fire, and significant mortality (P<0.05) was measured in size classes up to 6 cm dbh. Post-burn regeneration of white pine, however, was abundant at each site. Therefore, a single prescribed burn affected the age structure of white pine but will not have an important influence on long-term species composition of these stands. A fire return interval of at least 10 to 20 yr will be required to control white pine competition with fire-adapted species on the ridgetop ecosystems of the DBNF.