Toros Göknarı Ağaçlarında Ökse Otu ve Kabuk Böceği İlişkisinin Terpen Profilleriyle İncelenmesi

Summary

Secondary bark beetles generally attack physiologically weakened trees. Mistletoe, widespread in our country, is an important biotic agent that causes physiological weakening in trees. During preliminary field surveys conducted in the project preparation phase, it was observed that a large number of mistletoe-infested trees in the selected study areas had dried out and died as a result of bark beetle infestations. Identifying biotic factors affecting tree growth and development, as well as elucidating the relationships and interactions among these factors, is of great importance. The proposed project will be among the first studies at the national level and one of the few internationally to investigate host selection of bark beetles in mistletoe-infested forests using terpene profiles. Within the scope of the project, the effects of mistletoe-induced physiological changes in Taurus fir (Abies cilicica) trees on bark beetle population density will be examined, and host preferences of bark beetles in mistletoe-infested forests will be determined based on terpene profiles.

The study will be conducted in Taurus fir forests in the Niğde-Ulukışla. Pheromone traps were installed in the study area in early April 2025, and insects captured in the traps were collected 21 times until the end of September. Approximately 8,500 bark beetle individuals were obtained. Based on these findings, the most suitable period for conducting detailed tree-level measurements in the Taurus fir stands was determined to be between early June and mid-July. However, to further support the study, pheromone traps will also be installed in 2026 and monitoring activities will be continued. During this period, mistletoe infestation levels of trees will be determined using a six-class dwarf mistletoe rating system. Five trees will be felled from each mistletoe infestation class, together with five trees free from both mistletoe and bark beetle infestation, and five trees attacked by bark beetles. Whole-tree sampling will be conducted on the felled trees to determine mistletoe biomass and needle biomass. To assess tree-level bark beetle populations, each felled tree will be divided into three sections, and all entrance holes in each section will be counted and recorded. Bark will be removed from the sections, and all insects at the larval, pupal, and adult stages will be collected, while galleries and pupal chambers will be counted. Needle and wood samples will be collected from the same trees to determine terpene profiles. Terpene analyses will be used to identify volatile compounds, specifically monoterpenes and sesquiterpenes. General site characteristics of the sample plots and the attributes of the felled trees will be recorded. Monthly mean temperature, relative humidity, and total precipitation data will be obtained from the meteorological stations closest to the study area. All data obtained from the planned studies will be evaluated using appropriate statistical analyses.

The project consists of seven work packages and is planned to be completed within 12 months. The project team comprises one principal investigator and five researchers. As a result of the study, it is planned to produce papers that can be presented at national and international conferences and published in internationally indexed journals. The fieldwork of the project will also constitute the field component of the principal investigator’s doctoral dissertation.

This study, which aims to identify the primary causes of dieback in ecologically and economically important tree species, is expected to contribute to the United Nations Sustainable Development Goals, particularly “Decent Work and Economic Growth” (SDG 8) and “Life on Land” (SDG 15), as well as to the objectives of Turkey’s 12th Development Plan (2024–2028) regarding the conservation of natural resources. The project results will be shared with the Kayseri Regional Directorate of Forestry and the General Directorate of Forestry.