Tree growth is investigated within the intensive monitoring plots, following methods are used:
- periodic measurement of DBH (diameter at breast height), tree height and height to crown base in the 5 year interval,
- continuous measurement of diameter growth,
Measurement is done in all intensive monitoring plots. All standing trees within the plot, with the diameter of 5cm over bark, are measured. DBH is measured in the permanently marked measuring points, with the 0.1 cm accuracy, using measuring tape with a scale of direct recalculation of the stem diameter. Tree height and height to crown base are measured with the preciseness of 0.1 m, using hypsometer Vertex (combination of ultrasonic range finder and inclinometer). In the field also other data are recorded, connected to the further growth evaluation: in living trees it is crown damage (top and crown breaks), leaning trees etc., also newly removed and newly dead trees are recorded. The last mensurational measuring was done in winter period 2014/2015.
Continuous measurement of diameter growth
Two types of dendrometers are used: (1) girth bands of manual reading (2) electronic band dendrometers.
Girth bands of manual reading are installed in 8 plots of intensive monitoring. In the buffer zone 15 trees of the main species were selected, representing all diameter classes in the stand. Girth bands, consisting of steel band, spring and nonius scale, are placed at the stem, in the height of 1.3 m above ground. Measured values are read at the nonius scale with 0.1 mm preciseness. Reading is done by the observer, at the end of each month. Each reading is identified with the plot name, date and time of reading and tree number.
Besides girth bands of manual reading, also electronic band dendrometers are installed in 4 plots (so called D1 plots under the FutMon project). To install electronic dendrometers, group of 6 trees, of mean stem parameters, representing the main tree species in the plot, was selected in the buffer zone. Electronic band dendrometers DR26, connected to data logger, were installed. Data are recorded in one hour interval, once in six hours they are sent to FGMRI database, via GSM modem. All trees, equipped with electronic dendrometers, are, for control reasons and possible power failure, equipped also with the manual girth bands, to ensure continuity of data series measured.
In connection to other projects, for retrospective study of radial growth increment cores are taken in selected sample trees of the buffer zone. Normally 20 sample trees, representing mean stem, are selected. The cores are taken from two opposite sites of the stem, in breast height. The cores are sticked to the wooden supporter and polished. Than tree-ring widths are measured, with 0.01 mm accuracy. Data are further evaluated, using appropriate dendrochronological methods.