Estimating the needle area from geometric measurements: application of different calculation methods to Norway spruce

Abstract

Different calculation methods, based on needle geometry, for estimating both projected area (PLA) and total surface area (TLA) of foliage in Norway spruce [Picea abies (L.) Karst.] were compared. Seventy-eight shoots of four age classes were sampled from both the basal and top thirds of crowns. Three dimensions (the length, minor and major diameters) of needles were taken, and the needle shape was approximated to a parallelepiped or ellipsoid. There was a perfect coincidence of the measured and estimated values of PLA calculated as the width of the needle projection multiplied by needle length, and corrected for needle taper (method III), or when the needle projection was treated as a rectangle joined with half-ellipses at both ends (method IV). The most reliable estimations of TLA resulted from treating the needle sides as faces of the parallelepiped tapering at their ends in the form of half-ellipses. The ratio of TLA to PLA ranged from 2.2 to 4.0 depending on the needle morphology. Needle minor diameter (anatomical width; D 1 ) was found to be a better morphological index of the spruce foliage than needle flatness, i.e. the ratio of major to minor diameter. Expressing the factor for converting PLA to TLA as a function of D 1 considerably improved the precision of the estimates. Close relationships were established between specific leaf area, expressed on both a projected area (SLA P ) and total surface area basis (SLA T ), needle dry weight (R 2 was 0.799 and 0.852, respectively) and minor diameter of needles (R 2 was 0.701 and 0.554, respectively).

A review of light interception in plant stands from leaf to canopy in different plant functional types and in species with varying shade tolerance

“…2.2 and 4 in needle-leaved species (Fig. 2c, Barclay and Goodman 2000;Niinemets et al 2002b;Niinemets and Kull 1995a;Sellin 2000), implying large differences in plant leaf area and stand leaf area index (L) based on projected or total area. In addition, variations in A T /A P also result in significant differences in derived characteristics such as M A expressed per unit projected or total area (Fig.…”

Sensitivity of Norway spruce physiology and terpenoid emission dynamics to elevated ozone and elevated temperature under open-field exposure

“…P n and g s were calculated per total needle area, determination of which has been described by Räsänen et al (2012). In brief, total needle area was calculated from the projected needle area measured from scanned needles and the minor needle width (anatomical parameter) measured from needle crosssections (Sellin, 2000).…”

Allometric equations for estimating leaf area index (LAI) of two important tropical species (Tectona grandis and Dendrocalamus strictus)

“…LAI has a close correlation with many biophysical changes of a tree; therefore, estimation of LAI is an important aspect for understanding the functioning of tropical trees. Most of the published results come from temperate regions (Sellin 2000;Temesgen and Weiskittel 2006;Weiskittel and Maguire 2006;Urban et al 2009) and there are only a few reports for tropics (Maass et al 1995;Moser et al 2007). It is very important to have standardized equations for the estimation of LAI for tropical trees.…”

“…However, LAI is one of the most difficult parameters to quantify properly, owing to large spatial and temporal variability (Breda 2003). Many studies were carried out for LAI of temperate forests (Sellin 2000;Temesgen and Weiskittel 2006;Weiskittel and Maguire 2006;Urban et al 2008). A few studies on the LAI have also been conducted for tropical ecosystems (Maass et al 1995;Nascimento et al 2007).…”