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ŠUMARSKI LIST 9-10/2015 str. 41     <-- 41 -->        PDF

The results from the LSD multiple comparison test showed that the number of I. sexdentatus captured outside of the forest and forest edge was significantly (p<0.05) higher than those from forest interior (Table 6).
Body length of I. sexdentatus was measured to test the effect of forest edge via bark thickness and stem temperature regime on their growth. We found that mean body length of the pest was 5.76±0.07 mm at the forest edge, 5.55±0.08 mm at the forest interior, and 5.98±0.06 mm at the forest exterior in the study area (Figure 3). Therefore, body length of I. sexdentatus was significantly (p<0.05) higher on trees along the forest edges than those in forest interior (Table 7, Table 8).
Bark is an important part of the tree that provides protection of the inner living tissues against climatic effects, air pollution, mechanical damage, and biotic agents that attack the tree (Michel et al., 2011; Mmolotsi et al., 2012). Bark anatomy and the physiological condition of a potential host tree are crucial for the success of a bark beetle attack (Wermelinger, 2004). Bark thickness, as an important factor in breeding success for I. sexdentatus, generally increases with stem diameter and tree age. As forests age they become more vulnerable to agents of disturbance, such as high winds, fire, fungi, and bark beetles (Christiansen et al., 1987). In the present study, DBT and DBH of the trees along the forest edges were significantly greater than those in forest interior. Similar findings were obtained for Pinus radiata D. Don. in New Zealand (Berg, 1973), Quercus robur Linnaeus, and Fraxinus excelsior Linnaeus in the eastern part of the Czech Republic (Sálek et al. 2013). Gorte (2009) indicated that the adult mountain pine beetles (Dendroctonus ponderosae Hopkins, 1902), disperse with preference for trees of larger diameter