הזיקה בין הישרדות של עצי אורן ברוטיה לבין תבנית גדילת רוחב רב-שנתית

Climate change in recent decades has been characterized by rising temperatures and a decrease in annual precipitation in various regions in the world. These changes significantly affect the growth and survival of forest trees in the Mediterranean areas to the point of extensive tree mortality, which has also occurred in recent years in planted forests in Israel. Pine tree mortality involves the activity of bark beetles. It is not clear whether and to what extent drought affects tree sensitivity to lethal attacks by bark beetles. The present study examined whether stem increment could indicate mortality following a bark beetle attack. Annual radial stem increment occurs due to the formation of an annual ring that includes early wood (in the spring), late wood (in the summer), and resin ducts,which have a vital role in protecting against bark beetles. The present study examined whether growth parameters indicate tree sensitivity to bark beetles. To this end, we compared growth parameters of live and dead Pinus brutia trees in two independent stands in the Judean Mountains.These parameters included competition index,annual ring width, and density and dimensions of resin ducts in each ring. Annual ring width was uneven in the population. Growth indices of the dead trees were low relative to the surviving trees in the years before mortality. Variation in radial stem increment in two independent plots implies genetic variation in the population. The findings of this study indicate three variables that can be used to identify and even predict sensitivity to bark beetles in Pinus brutia trees: (a) low and constant annual growth over the years; (b) poor growth following a drought period; (c) reduced density and size of resin ducts.There is concern that the current low mortality rate of Pinus brutia stands in Israel will accelerate with the worsening drought conditions expected in the coming decades. Therefore, it is necessary to identify individual trees with the most appropriate growth indices to form the infrastructure for the future Pinus brutia plantations in Israel.