The impact of drought on natural Bulgarian forest ecosystems is an indicator of the potential effect of further warming and drought, resulting from global climate change. Natural ecosystems have been preserved in excellent condition in the forests of Bulgaria. The data on the distribution of forests in Bulgaria according to altitudinal belts as well as precipitation over the territory of Bulgaria are taken from D. Kostov et al. The situation with Pinus sylvestris forests is the same, judging from the data from representative ecosystems in the V. Serafimov station for 1976-1995. Ecological conditions for forest vegetation in Bulgaria changes according to altitude as well as geographical location of the terrain, from north to south and from west to east. The state of natural forest ecosystems in Bulgaria is depends on the vitality of the main tree species in them—Finns sylvestris, Abies alba, Picea abies, of the conifers, and Fagus sylvatica, Quercus sp.