Утицај климе на раст и виталност стабала у зависности од хоризонталног и вертикалног распрострањења букових шума / Impact of climate on growth and vitality of trees in depending to horizontal and vertical distribution of beech forests

The PhD thesis studies the climate influence on European beech forests in the Republic of Serbia and Republic of Srpska. European beech is a species that tolerates droughts, but if the dry periods often recur, they can negatively affect growth and vitality of these forests. Considering the increasing number and the duration of dry periods, according to various climate scenarios, in the future it can be expected that areals of the beech stands will be moved to the higher altitudes. The aim of this paper was to investigate the climatic effect on the growth and vitality of beech trees in two different climatic zones (Illyrian and Moesian provinces), depending on the vertical diffusion of beech forests (lower limit, ecological optimum and upper limit), considering the long-term influence of temperature and precipitation on growth and vitality and to identify the influence of extreme weather conditions on the growth and vitality of beech trees. The results are presented separately by sites, and then they are classified and unified by geographical zones and altitudes. Descriptive statistics for the sampled trees has been done for each site, the chronologies of these trees were showed, and the climatic characteristics of the area were analyzed. The width of tree rings is correlated with the air temperatures and the amount of precipitation. The influence of extreme weather conditions on the growth of beech forests has also been analyzed. The results show that the climatic influence on the growth of beech trees is stronger in the Moesian than in the Illyrian province. Chronology of trees of the lower limit has stronger peaks than the chronology of trees that are in the optimum and at the upper limit of the vertical diffusion of beech forests, which means that the climate change significantly influenced the width of the tree rings at lower altitudes. In beech forests in Serbia and the Republic of Srpska there is decrease in the width of the tree rings, i.e. the diameter growth depending on the change in air temperature and the amount of precipitation. This reduction is stronger at the lower limit and in the optimum than at the upper limit of the vertical diffusion of beech forests, but it is still not large-scaled to have the influence on the movement of areal of beech forests and the moving of beech to higher altitudes. In the Illyrian and Moesic provinces, in all three zones of vertical diffusion of beech forests, the decrease in the width of tree rings in the exceptionally droughty years has been recorded, and in some regions the decrease in the width of tree rings has also been recorded in years after extremely dry years.