Few branches of the biological sciences have developed to such an extent as has ecology in the recent decades. The successful development of this science is directly related to need to create a sound scientific basis by which we can control our diminishing natural resources and integrate this with the control of biological systems of the component species. Studies on the bioenergetics of ecosystems, as well as on the home­ ostatic mechanisms functioning at the populations and biocenoses levels are of great importance in this respect. The results of these studies are very significant in forestry management which deals with multiannual tree communities - forest stands. It is particularly important in this of the necessity for the possible respect for economic planning, in view prolonged maintenance of forest biocenoses as stable systems. Neither in the present nor in the immediate future can be protection of forest ecosystems consisting of natural plant and animal communities be achieved by the cultivation of resistant forms or the intensification of chemical intervention.