Effects of forest roads on Ips sexdentatus infestation in black pine forest

Abstract

Forest roads are important transportation equipment through forested areas in the rugged,mountainous terrain of northern Turkey. Forest roads harm forest ecosystems due to boththe manner in which they are established and how they are used afterwards. Damage totrees that occur during road construction through forests stresses trees, which facilitatesoutbreaks of bark beetle populations. Bark beetles are significant risk to the health andproductivity of Turkish pine forests and to pine forests worldwide. In particular, Ipssexdentatus (Boerner) (Coleoptera, Curculionidae, Scolytinae) is a particularlydestructive species of bark beetle in Turkish forests. Their damage to coniferous treesthreatens the sustainability of the forest ecosystems. This study primarily aims to assessthe intensity of damage that I. sexdentatus inflicts on Pinus nigra J.F.Arnold standsrelative to several parameters: the distance to the nearest forest road, aspect (shady -sunny), slope (0–15% or >15%), and other stand characteristics. In this study, we showhow damage by an I. sexdentatus infestation in pure black pine stands varies withdistance to forest roads and in situ edaphic factors. We sampled 45 plots (400 m2each),slope, aspect and distances to the nearest forest road was determined using ArcGISsoftware and the region’s road network overlays. Results showed that trees located within100 m from the nearest forest road were the most severely damaged ones. The intensity ofI. sexdentatus damage was about 16% in a hectare. Trees that were in 16–20 cm diameterclass were damaged more often. I. sexdentatus damage did not show any significantcorrelation with the slope, aspect or degree of canopy closure.