The R. R. Reynolds Research Natural Area in Southeastern Arkansas: A 56-Year Case Study in Pine-Hardwood Overstory Sustainability
The R. R. Reynolds Research Natural Area is a 32-ha pine-hardwood forest in southeastern Arkansas, U.S.A. that originated from diameter-limit cutting of the virgin forest before 1915. In 1935, these 32 ha were reserved from timber management. Between 1937 and 1993, eight inventories were taken of all living trees > g-cm DBH, using 2.5-cm DBH classes within three species groups: Pinus spp., Quercus spp., and other hardwoods. In 1994, all standing dead snags of pines and hardwoods > 9 cm-DBH were inventoried by 2.5-cm DBH classes. During 56 years, the overstory pinc-hardwood ratio remained stable in terms of relative basal area, but pine density decreased with a commensurate increase in hardwood density. In 1993, pines represented 63% of basal area but only 23% of stem density. Just before the 1993 inventory, a pine bark-beetle infestation developed on the area, and within one year the pines lost about 2.5 m2/ha in basal area and had 180% more snags than were contributed by hardwoods. The overstory pine component is decreasing in density as a result of natural senescence and the allogenic effects of bark beetles. Hardwood species are expected to eventually dominate the forest because shade-intolerant pint regeneration will not develop to maturity beneath the closed hardwood canopy which can be altered only by catastrophic natural disturbances or anthropogenic intervention.