Estimation of volume, total and projected area of Scots pine needles from their regression on length

摘要

Breadth, thickness, perimeter and area of serial transverse sections (TS) of Scots pine (Pinus sylvestris L.) needles from non-fertilised (0) and combined NPK-fertilised (F) and irrigated fertilised (IL) trees of northern Swedish origin were measured by projection microscopy. The accuracy and precision of the method were analysed. Regressions of the above characters and of total (A,) and projected (A,) area and volume on the length of single needles were calculated, to make possible their non-destructive estimation from length. Needles were semi-fusiform, rather than semi-cylindrical, as is assumed for some conversion factors from projected to total area. The assumption of a semi-cylindrical form caused total needle area to be systematically overestimated. The mean basic dimensions of the longer (F, IL) needles exceeded those of (0) needles: breadth by 11%, thickness by 21%, TS area by 32% and perimeter by 9%. Regressions of A, and A, on length were linear over the range 15-70 mm; that of volume was curvilinear. Both (0) and (F, IL) needles lay on the same regression line. Joint regressions gave estimates of mean A, mean A and mean volume having 95% confidence limits of (2.3, (2 .0 and (4.4%, respectively. Comparisons with published sources suggest that the regressions should be applicable outside the range of northern morphological types within Scandinavia, but that overestimates of area and volume may occur if they are applied to material of Central European origin.