Fig. 4 Distribution of soil exchangeable Ca pool vs. soil Ca depletion rate for Panola Mountain Research Watershed and several other intensively studied sites in the southeastern USA. American beech, Fagus grandifolia Ehrh. (A) (Johnson and Lindberg, 1992); chestnut oak, Quercus prinus L. (B) (Johnson and Todd, 1990); mixed conifer and southern hardwood (C) (Johnson and Todd, 1990); Quercus–Carya spp. (D) (Johnson and Todd, 1990); Quercus spp. (E) (Rick Web, Univ. of Virginia, 1995, personal communication); loblolly pine, Pinus taeda L. (F) (Richter et al., 1994); mixed southern hardwood (G) (Johnson and Lindberg, 1992); P. taeda (H) (Huntington, 1996); P. taeda (I) (Johnson and Lindberg, 1992); mixed conifer and southern hardwood (J) (this study); P. taeda (K) (Johnson et al., 1988b); P. taeda (L) (Johnson and Lindberg, 1992); slash pine, P. elliotti Engelm. (M) (Johnson and Lindberg, 1992); eastern white pine, P. strobus L. (N) (Johnson and Lindberg, 1992); red spruce, Picea rubens Sarg. (O) (Johnson and Lindberg, 1992)
