Needle traces as indicators of growing conditions in Scots pine (Pinus sylvestris L.)

Abstract

Needle retention (number of needle sets) and needle density (number of needle pairs per centimeter of shoot) were surveyed on Scots pines in five forest regions of Slovakia. The Needle Trace Method (NTM) was used to determine needle retention and needle density along the main stem retrospectively for the last four decades. In all forest regions, the values of these indicators varied from year to year. However, in Záhorská lowland, Vtáčnik, Krupinská plain, and High Tatras, the trends of both observed indicators were constant over the time series. The situation was different in the Levočské hills, where the needle retention displayed a decreasing trend and needle density an increasing trend. These trends probably reflected a long-term stress of air pollution on pines in this forest stand.Keywords: needle retention; needle density; environmental and anthropogenic impacts JOURNAL OF FOREST SCIENCE, 49, 2003 (1) branches was assessed visually whorl by whorl at a precision of 0.1 needle set (data for the current year 2000 or 2001). Then, the branches were cut from the main stem. Using a chain saw and a waterproof pen-marker, a linear mark was drawn onto the stem to indicate the east-facing side. The stems were cut into pieces respecting annual shoots (i.e. each piece represented a section between two neighboring whorls). The lengths of the annual shoots (height increments), starting from breast height to tree top, were measured and considered for further needle trace survey. Every shoot was shortened for a bolt approximately 15 cm long. Tree code and numerical order within the stem were marked on the bolts. The bolts with discs cut off at breast height were transported and dried at a room temperature for a few days.The annual radial increments were measured from the breast-height discs. The bolts were longitudinally split with an axe to get their central parts and all the rings containing needle traces on the marked east-facing side. The ends of the bolts were polished with an electric grinding machine to make the rings easily distinguishable. Then, angles were drawn on both ends of the bolts delimiting the examined area. The precise length of every bolt was measured. The bolts were planed manually ring by ring, and the number of needle traces in each ring was recorded. The data on height increment, radial increment, angles α 1 and α 2 , bolt length and number of needle traces in each ring were processed using the computer program NTMENG version 5.1 (AALTO, JALKANEN 1998b). The computer program calculates summer and winter retention (i.e. number of needle sets in growing season and in dormancy season), annual needle loss (differences between the number of needle sets in summer and in successive winter), needle density per cm of shoot, number of needle pairs in leading shoot and total number of needles on stem for every year of the tree's life. More detailed information on the procedure of the NTM, as well as the formulas to calculate the particular parameters, are in the manuals "The needle trace method"...

Carbon stock in aboveground biomass of vegetation at the High Tatra Mts. twelve years after disturbance

“…As for spruce trees, the annual foliage fall was calculated as 1/5 of their autumn standing stock (see e.g. Schmidt-Vogt 1977;Sander & Eckstein 1994) and for pine as 1/3 of the needle stock in autumn (Konôpka et al 2003). To estimate the carbon amount in tree foliage, the concentrations of this element were taken from our previous work dealing with the same sites .…”

Aboveground Net Primary Production of tree cover at the post-disturbance area in the Tatra National Park, Slovakia

“…Schmidt-Vogt 1977) and for pine as 1/3 of needle standing stock in autumn (e.g. Konôpka 2003). The mean NPP was calculated separately for each transect by averaging NPP from all the plots of the specific transect.…”