The inluence of climate change on tree species distribution in west part of south-east europe

Ecological niche is n-dimensional hipervolume space defined by amount of ecological factors in which population of certain species is able to persist. From ecological point of view there are fundamental (FEN) and realized niche (REN). Fundamental ecological niche is space which certain species occupies in lower competition of other species or in absence of natural antagonists. Opposite to fundamental niche realized niche is space in which certain species accrues and persists in presence of competition with other species (Hutchinson, 1957). To fully understand ecological niche is rather complicated concept. Ecological niche can be imagined as multidimensional space in which each ecological factor is presented by vector different in amount and direction of action. Amount of ecological factor action is shown in his importance for accruence and development of species, while direction of action can be positive or negative on species prevalence. Entirely understanding influence of each ecological factor on certain species space distribution is fairly difficult since between ecological factors exist certain dependence. Importance of ecological niche on appearance and accurance of certain species can be observed on few resolution levels. Species during ontogeny development develops different needs toward ecological factors. Seed of all tree species for germination and initial growth needs only temperature and soil moisture, for further development young plant needs higher amount of sun radiation, moisture, nutrients and lower competition of mature trees. If ecological niche is observed from the view of population in certain geographical climate than climatic and geomorphologic (relief) factors have higher importance for spatial distribution and formation of species areal. 12