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ŠUMARSKI LIST 9-10/2015 str. 39     <-- 39 -->        PDF

I. sexdentatus. Five study sites were chosen to deploy Lindgren® funnel-type pheromone traps baited with commercial pheromone Ipssex®. Fifteen-unit pheromone traps were set in 5 replicate blocks of three traps per block (Figure 2). Experimental periods ranged from early to mid-summer, comprising the part of the flight period of I. sexdentatus. Traps were placed from 02 June to 28 July 2012 along the forest edges. All traps were fastened to wooden sticks with the top of the trap at 1.5 m above the ground. The quantification of captured insects took place every 7-10 days by counting insects, or by measuring volume of the insects if the catch were greater than 500 insects per trap.
In each study area, a total of 60 pine trees (stem >8 cm diameter at breast height (DBH), 1.3 m above ground level) were measured for DBH and double bark thickness (DBT). DBT and DBH were measured with a bark gauge and a diameter tape, respectively. After that, mean DBT and mean DBH were calculated. Bark thickness values were determined by averaging two bark thickness measurements taken at the angle of 90 degree. On standing trees, DBT is the double of averaging two measurements (Sonmez et al. 2007).
Statistical analysis – Statistička raščlamba
All statistical analyses were performed using SPSS® 19.0 for Windows®. We analyzed the edge effects on I. sexdentatus abundance and body length of the developed adults using one-way analysis of variance (ANOVA). Independent samples t-test was applied to test the DBT of the trees. If differences were significant, a LSD multiple comparison test was performed to identify variation between pairs of means. Means were considered to be significantly different when P<0.05.
An aim of this research is to find out whether forest edges had any significant effect on the DBT and DBH of the trees. This study showed that DBT of the trees along the forest edges were significantly higher than those in forest interior (p<0.05) (Table 1 and 2).
Diameter of tree trunks (DBH) along the forest edge and in the forest interior significantly differentiate (p<0.05) in the study area (Table 3, 4). Diameter of tree trunks (DBH) was higher along the forest edge.