Leaf and Bark Area Distribution in a Pine Forest

Abstract

Vertical profiles of element surface areas of a tree stand are needed in many micrometeorological and related studies, but are very laborious to measure even with low accuracy. Simple models to deduce such distributions are, therefore, highly desirable. In this study, surface area profiles were deduced for needles, shoot axes, branch bark surface, stems and cones from extensive measurements of twelve Scots pine trees at Jädraås, Central Sweden. Errors caused by the small sample were assessed as a quarter of the total area. Non-transpiring “bark” area may amount to a quarter of the total and should not, as usual, be neglected.

In agreement with several previous studies, the results showed that canopy needle area distribution was close to normal with the mean in the mid-canopy and with a standard deviation equal to 20 % of the depth. Canopy needle area distribution was best predicted, however, by the sum of individual tree crowns of idealized, triangular form. Individual crown forms were not very important for prediction of the vertical form of the canopy and both distribution models required measurements of individual tree heights, crown bases and breast-height diameters. Shoot axes and branch bark surface areas were well described as 1/20 and 1/8 of the seasonally maximum needle area at the same height. Stem area was well represented as a cone with dimensions given by mean breast-height diameter and stand height.