THE EFFECTS OF SITE, STAND DENSITY, AND SAPWOOD PERMEABILITY ON THE RELATIONSHIP BETWEEN LEAF-AREA AND SAPWOOD AREA IN LOBLOLLY-PINE (PINUS-TAEDA L)

The relationship between total leaf area (LA) and sapwood area (SA) wa s studied in four stands of approximately 30-year-old loblolly pine (P inus taeda L.) representing extremes of stand basal area and site inde x. Nine trees (three dominant, three intermediate, and three suppresse d) were randomly selected from each stand for determination of LA and SA. Sapwood permeability with respect to height in stem and radial dis tance from the pith was determined from one other tree from each domin ance class in each stand. Stem cross-sectional SA at breast height, mi d-stem and base of live crown were linearly related to LA. SA at the b ase of live crown was a better predictor of LA on some sites than SA a t breast height. The effect of including sapwood permeability (average sapwood permeability x area of sapwood) in the LA prediction equation s was minimal. Regression equations for LA had different slopes betwee n basal area classes but not between sites. Because of the larger regr ession slope of the LA prediction from SA in the low basal area stands (more leaf area per unit of sapwood), it is hypothesized that carbohy drate production in low basal area stands is allocated proportionally more to leaf or root tissue than sapwood at breast height and mid-stem . This implies that leaf area is the controlling factor in the LA-SA r elationship.