Root Habits of Longleaf Pine and Associated Species

Abstract

Longleaf pine, Pin fs palustris Miller, at one time covered an area in the south of more than 30 million acres. Today, owing to the inroads by agriculture and by other species following the cutting of the original timber, a survey in 1934 and 1935 showed that less than 80 per cent of this area is still considered longleaf pine forest land. According to this survey, about 15 million acres are in saplingand sawlog-size stands of longleaf, nearly 2.5 million acres in reproduction, and the remaining 7 million acres are clear-cut and have failed to reproduce satisfactorily. It is estimated that nearly 30 per cent of the longleaf reproduction area is stocked satisfactorily with 900 or more seedlings per acre.1 The remaining 70 per cent shows a low stocking of seedlings, ws hich is principally due to destruction by uncontrolled fire, to damage by hogs, or to a lack of seed trees. The characteristic stunted condition of the longleaf pine seedlings, which lasts 4 to 10 or more years, makes them especially susceptible to fire and hogs as well as to annual defoliation by the brown-spot needle disease (Septoria acicola [Thiim.] Sacc.). When the pine seedlings emerge from the stunted condition, they begin rapid growth in height, and the danger of disease is considerably reduced. Since over 50 per cent of the extremely large clear-cut area (7 million acres), that must be reforested before becoming again productive, averages 3 or more seed trees per acre, while the remaining half has only 1 or 2 seed trees per acre, if the factors of destruction can be controlled, satisfactory natural reproduction should be possible on three-fourths of it. A recent study (1938), in which the writer found that the removal of grass from the vicinity of 12-year-old longleaf pine seedlings stimulated their growth to a marked degree, suggests that the roots of the grasses compete with those of the pine seedlings and that by the removal of the grasses this competition may be eliminated, permitting the pines to develop more rapidly. This present study, therefore, was designed to determine the characteristics of the roots of the pine seedlings and of other species growing in the same area, and also to determine what relationship exists between the roots of the pine seedlings and those of the other species commonly associated with them. 1 The estimates were supplied by the Survey Division of the Southern Forest Experiment Station.