DIGITALNA ARHIVA ŠUMARSKOG LISTA
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|ŠUMARSKI LIST 9-10/2015 str. 38 <-- 38 --> PDF|
genera, including Pinus L., Picea A. Dietr. (Pinaceae), Larix Mill. (Pinaceae), and Abies Mill. (Pinaceae) (Balachowksy, 1949; Pfeﬀer, 1995; Lopez and Goldarazena, 2012). This pest is distributed throughout Turkish conifer forests excluding Southeastern Turkey. It occurs mostly on Pinus spp. and Picea orientalis (L.) Link. having two generations per year.
Species richness and density of forest pests depend on some biotic and abiotic factors, such as forest structure, climate, topographic conditions, parasites, pathogens, and associated organisms. Fragmentation, one of the most influential factors on forest pest population dynamics, changes the spatial structure of the landscape, increases the amount of edges and induces changes in the abiotic and biotic environment (Marozas, 2014). Ewers and Banks-Leite (2013) indicated that forest fragmentation, and the creation of forest edges, exposes parts of the forest stand to external climatic conditions, reducing the ability of a forest to buffer its internal microclimate from those more extreme macroclimate conditions. Therefore, forest fragmentation and creation of forest edges cause some changes in the environment, including changes in wind, humidity, throughfall deposition, radiation, predation, parasitism, and species interactions (Murcia, 1995; Donovan et al., 1997; Brazaitis et al., 2005; Wuyts et al., 2008; Marozas et al., 2009; Marozas, 2014). For this reasons, habitat edges exert a strong influence on spatial patterns of biodiversity for many taxa in many ecosystems (Ries et al., 2004; Ewers et al., 2013).
Effects of forest edges on bark beetles are poorly understood. Many factors (e.g. tree species, bark thickness, topographic factors, and edge effect) may affect the ecology and biology of bark beetle species. Previous studies have shown that the effects of forest edges differ significantly between bark beetle species. Peltonen and Heliovaara (1999) reported that attack density, number of offspring emerging and number of new bark beetles per mother gallery were lowest in open area bolts and increased towards the forest interior. On the other hand, Jakuš et al., (2003) indicated that I. typographus usually attacks trees on forest edges and on borders of clearings.
Further studies are needed to establish the linkage between effects of forest edges and population dynamics of bark beetles. The present study investigated the edge effect of Pinus nigra Arnold stands on the population level and the body length of I. sexdentatus.
Materials and Methods
Materijali i metode
Study area – Područje istraživanja
The sampling was carried out in 2012–2013 in the Dikmen Forest District of Kastamonu Regional Directorate of State Forests located in northwestern Black sea region of Turkey (Figure 1). The study area is mostly covered by natural P. nigra stands. In the study area, mean tree age was 47±7.35, mean tree diameter was 26±6.12 cm, and mean tree density was 2158 stems/ha. The altitude of the study area various from 1340 m to 1400 m (a.s.l.). Climate is generally characterized by cold winters and semi-arid summers. In winter, the ground is covered with snow, which accumulated more heavily on the upper elevations than lower elevations in the study area. The annual mean precipitation is 478.5 mm and the annual mean temperature is 9.8 °C. Average monthly temperature ranges from –1.0 °C in January to 20.3 °C in July (1954–2013 meteorological data from Kastamonu Meteorology Station) (Anonymous, 2015).
Sample sites and field methods – Pokusne plohe i terenski rad
In this study, three factors (forest interior, forest edge, and forest exterior) were determined to evaluate the effects of forest edges on the abundance and body length of