SURROGATES FOR FOLIAR DRY-MATTER IN LOBLOLLY-PINE

Surrogates of foliar dry matter of trees commonly are used in applicat ions of modeling and sampling. Some surrogates are linearly related to foliar dry matter. In this study, the linear relation between foliar dry matter (F) and cross-sectional area of the bole at the base of the five crown (A) was examined in loblolly pine (Pinus taeda L.). In add ition, a linear relation was established between F and BR, where B is the cross-sectional area of the bole at breast height, and R is the ra tio: (length of the five crown)/(tree height minus breast height). Slo pes (c1 and c2) of linear models (F = c1 A and F = c2 BR) were estimat ed with maximum likelihood procedures with data gathered in: (1) June through mid-August 1984, in central Louisiana, (2) August and Septembe r 1991, in Virginia and North Carolina, and (3) August and September 1 992, in central Louisiana. The estimates of both c1 and c2 obtained fr om data gathered in June through mid-August were greater than the esti mates obtained from the two sets of data gathered in August and Septem ber. The estimate of c2 was as precise as the estimate of cl obtained from each of the three sets of data. BR appears to be as good a surrog ate for F as A. Linear relations between foliar dry matter and cross-s ectional area of first-order branches in lower, middle, and upper crow n strata also were examined. Branches in the lower stratum had less fo liar dry matter per unit of cross-sectional area than branches in the other two strata.