Sections measured from the tree base up to the diameter of approximately check details 7–9 cm in the thinner end of the stem were distinguished on the windfalls: (1) 0.5 m-long sections and (2) sections comprising 10% stem lengths of fallen trees without tops (Fig. 1). 0.5 m-sections distinguished in such a manner so that the last section also equalled 0.5 m and the final diameter was within the range of 7–9 cm. Then, the trees were measured for: (1) the diameter at breast height and diameter over bark in the mid-length of each stem section, (2) the initial
diameter, (3) the final diameter and (4) the total length and the length of the lying tree without top. Fig. 1 a P. abies windfall. b The windfall after branch and top removal; marked are the boundaries of fifty 0.5 m-long sections and the ten 10% stem length sections (length of a fallen tree without
top is 25 m, diameter at the thinner end is 8 cm) The sex ratio and the number of I. typographus maternal galleries were calculated using the method of entomological section-based analysis. It consisted in the removal of bark plates from the successive 0.5 m-long stem sections. To avoid bark damage during its removal the circumference, sides and upper part were incised in the successive sections of the stem. For each 0.5 m-long section two bark pieces from the upper area and one bark piece from the bottom area of the stem were taken. The bark pieces collected from the stems were transported to the laboratory on the same day. In addition to the R428 purchase I. typographus maternal galleries (1) the number of galleries of Pityogenes chalcographus and Ips amitinus, (2) the number of maternal galleries of Hylurgops palliatus and Dryocoetes autographus, (3) the number of entrances of Xyloterus lineatus to wood were counted. The stem form of a coniferous tree can be expressed by Kunze’s equation (Inoue 2006): $$ r = \sqrt bl^c $$ (1)where r is stem radius, l is stem length from tree tip, b and
c are coefficients. The stem surface area s of the tree can be computed by the following Hydroxychloroquine formula: $$ s = 2\pi \int\limits_0^h r\sqrt 1 + \left( \fracdrdl \right)^2 dl $$ (2)where h is the length of the lying tree without top. The total colonisation density of each P. abies stem was calculated: (1) after summing of I. typographus maternal galleries in all 0.5 m-long sections and (2) after calculating the stem surface area. One-way ANOVA followed by post hoc Fisher’s least significant difference (LSD) procedure (α = 0.05) for multiple comparisons was used to analyse differences in I. typographus attack densities in individual sections of windfalls. To determine the relationships between the number of I. typographus maternal galleries in selected 0.5 m-long stem sections and the total density of stem infestation the analyses of correlation and regression were used.