Our long-term (more than 20 years) studies of Altai forests formed by Siberian stone pine (Pinus sibirica du Tour) allowed us to fetch out many pecularities of forming of these forests and their functioning. The representativeness of the Aktru mountain glacier basin by hydroglacioclimatologic showings (Tronov, 1973) allowed us to assume the general trends and tendencies are common for the Altai, though influ - ence of local factors still define the details (Timoshok et al., 2008). We found almost all successions in mountain glacier basin Aktru is directed to the forming of Siberian stone forests. This forming may be direct, like transformation of tundra to stone pine forest during raising of treeline and forest line or during post-fire secondary succession in the larch forests of the Aktru river valley (Timoshok, 2020a) or be indirect as during primary successions at Malyi Aktru glacier forelands and gla- cionfluvial deposits of the Aktru river (Timoshok, 2020b,c). This common direction allow us to assume the si- berian stone pine forests serve as kind of attractor, similar to F. Clements conception of ecosystem climax. Signs of similar changes in the past was confirmed by the data of spore and pollen analysis (Blyakharchuk T.A. et al., 2004). The analysis also confirms that changes of Altai forest composition occurred in the past: Siberian stone pine forest were much more common than now in the humid periods with lower impact of fire distur- bances while larch was as common as now in dryer periods. Siberian stone pine forests have high stability because of longevity of Pinus sibirica and its ability to pro- duce cones and seeds until the moment of physical death of the stone pine individual. Their stability is proven by the fact these forests survived Little Ice Age without significant changes (Timoshok at al., 2016). These for- ests have complex mosaics of forest types. Each element of mosaic exist in its own cyclic succession. These elements of the forest changed when trees become older and die, but new Stone pine forest is forming on the place of the dead element. So entire forest remains existing, though trees in some element of its structure may die. Such shortened cyclic succession is untypical for the Siberian stone pine as in the Weat-Siberian plain such succession include a stage of deciduous forest, not existing in the Altai mountains.