Surface areas, lengths and volumes of Picea abies (L.) Karst. needles: determination, biological variability and effect of environmental factors

Abstract

Summary. A method for the rapid determination of the lengths and surface areas of very large samples of needles of Picea abies (L.) Karst. using a computer-aided image analysis system was developed. Two independent methods for measuring non-destructively the volumes of individual needles and of all needles attached to a twig were devised. The surface areas and lengths of about 38000 needles sampled from the three youngest needle age-classes (1986, 1985, 1984) of 48 trees approximately 130 years old at four sites in the Fichtelgebirge mountains (N. E. Bavaria, FRG) were measured. The frequency distributions of lengths and areas for each site and age-class are given. Variability of needle size was fairly large. Even though the sites differed in climate, soil, and air pollution levels no consistent effect of these factors on needle size could be detected. Needle lengths and surface areas did not correlate with either the total chlorophyll content of the needles or the degree of crown thinning. The needle surface area (in mm 2) of fully developed P. abies needles can be estimated by the empirical equation surface area = 4.440 x needle length -24.8 (r = 0.937), and the needle volume (in mm 3) by needle volume = 0.208 x projected needle area 1.353 (r = 0.969).

The growth and gas exchange response of soil‐planted Norway spruce [Picea abies (L.) Karst.] and red oak (Quercus rubra L.) exposed to elevated CO2 and to naturally occurring drought

“…Riederer et al (1988) have analyzed projected areas of needles stuck onto paper, using a photocopy machine and a computer-aided image analysis system. However, although this is a more empirical method than the attempts made to model the shapes of needles (e.g.…”

Field investigations of nitrogen dioxide (NO<sub>2</sub>) exchange between plants and the atmosphere

“…The total enclosed leaf areas were 0.99 m 2 (tree 1) and 1.02 m 2 (tree 2). As stomata are distributed over the whole needle surface in the case of spruce (amphistomatic leaves) the total leaf area to be taken into account was estimated by multiplication of the projected area with the factor 2.74 (Riederer et al, 1988). During the field measurements leaf area varied with leaf flushing and was interpolated retroactively for the individual measurement periods.…”

The dynamic chamber method: trace gas exchange fluxes (NO, NO<sub>2</sub>, O<sub>3</sub>) between plants and the atmosphere in the laboratory and in the field

“…The needles of spruce have stomata on the entire needle surface, therefore the area of the whole surface was used. For needle surface area calculation the single surface area was multiplied by factor 2.74 according to Riederer et al (1988). All exchange measurements started one day after enclosure in order to allow an acclimatization of the branch or plant.…”