Effects of different ecological and silvicultural factors on beetle in the Turkish fir (Abies bornmulleriana Mattf.) ecosystems

摘要

To study the bark beetle attacks on Turkish fir stands and to determine the principle site and stand factors influencing beetle attacks, trap log method was used in the Western Black Sea Region of Turkey. The study was carried out in ten different locations prior to flying time in February 2003. On each experimental plot, three healthy fir trees with 30-50 cm diameter and 200 m apart were cut down with a chainsaw. From each sampling tree, needles were sub-sampled for determination of specific leaf-area and macro-nutrient concentrations. In addition, on each experimental plot, crown closure, basal-area, and stand density were measured. To determine the bulk density and nutrient concentrations of the soil, samples were taken around trees on each plot.The relationship between measured stand variables, the number of beetle species and beetle populations were evaluated using correlation and stepwise multiple regression procedure. Eight different species belonging to four different families from Coleoptera were identified in examining the trap logs. Six of these eight species (Pissodes piceae Illig., Pissodes notatus Fabr., Cryphalus piceae Ratz., Pityophthoms pityographus Ratz., Xyloterus lineatus Oliv., Pityokteines curvidens Germ.) were identified as harmful beetles (HB). The other two (Thanasimus formicarius L. and Rhizophagus dispar Payk.) were identified as predator species. The analysis showed that the total number of HB increased as the site's slope and needle specific leaf area increased. However, as needle N concentrations increased, HB population decreased. Increased Ca concentration in fir needle reduced total insect attack.