Needle area measurement by the cut method and estimation of specific leaf area in Cryptomeria japonica

Abstract

AbstractNeedle surface area in Cryptomeria japonica was measured using a newly proposed cut method. Sample needles of various lengths were taken from foliage shoots belonging to various height layers of nine trees growing at three sites. Needles were cut into small pieces with a hand‐made cutter made of razor blades and washers. By measuring the circumference and thickness of each piece, its lateral area was calculated and summed to give the total surface area of the needle. For estimating the surface area of a needle (s), two linear parameters of needle size termed yn* and /were proposed:yn* was the distance between the needle tip and the uppermost point of attachment of the needle to the shoot, while l was the distance between the needle tip and the lowermost point of attachment. The power‐form relationship between s and l was superior to the s‐yn* relationship, since the former did not differ significantly among shoots of different diameter. Based on the s‐l relationship, the total surface area of a shoot was estimated from the l‐census of the shoot. Specific leaf area of a shoot (SLA), defined as half of the shoot surface area divided by the dry weight of the shoot, decreased from 90 to 3 [cm2g(dry wt)−1] with the diameter of the woody tissue of the foliage shoot.