Ecological and coenotic description of siberian stone pine (Pinus sibirica Du Tour) at the highest line of its distribution in the Central Altai

A part of high boundary of Siberian stone pine (Pinus sibirica Du Tour.) distribution in the Central Altay is situated at the most high-altitude part of Severo-Chuisky range (glacier basin Actru), at the altitudes 2 100-2 500 m a.s.l. Siberian stone pines are involved in forming tree storey of old-age forests, postfire Pinus-Larix forests, Larix and Pinus forests, young Larix forests on fluvioglatial deposits and in the forest-tundra ecotone of this area. Pinus sibirica absolutely predominates in the tree storey of old-age periglacial forests. These forests are situated at altitudes 2 100-2 300 m a.s.l. Siberian stone pine is an edificator of these forests, it constitutes 90-100% of tree storey and exists between 65.1 and 70.7 stage of I.A. Tsatsenkin moistening scale and between 6.6 and 8.6 stage of active soil richness of I.A. Tsatsenkin. Siberian stone pine plays also a different role in the postfire Pinus-Larix forests. Its constitution depends on angle and exposition of slopes. It predominates in small fragments of young Pinus sibirica forests here. In the tree-storey it constitutes 10-20% of trees and in the Larix forests there are only single trees of this species. In these forests Siberian stone pine grows between 64 and 68.3 stages of moistening scale and between 7 and 9.4 stages of active soil richness scale.Young individuals of Siberian stone pine are present in tree-storey of young Larix forests on fluvioglacial deposits at the bottom of Aktru river as single trees. Here, Pinus sibirica survives between 65 and 68.3 stages of moistening scale and between 7.6 and 9.1 stages of active soil richness. At the head of Aktru river Pinus sibirica forms a modern high forest line in the forest-tundra ecotone communities. In the highest part of the ecotone there can be encountered only singular individuals of Siberian stone pine. At a lower line of the ecotone Siberian stone pine constitutes 60-80% of all trees. Moistening in the ecotone lies between 62.8 and 69.6 stages and active soil richness between 6.8 and 9.5 stages. By means of ordination on the basis of standard ecological scales ,it was determined that with a significant diversity of habitats and plant communities with Pinus constitution, the range of tolerance for the species are 8 stages (from 62.8 to 70.7) according to the moistering scale and 3 stages (6.6 to 9.5) according to the soil richness scale. It was established that Siberian stone pine at the highest boundary of its proliferation occupies habitat series with moist-forest moistening and poor soils and proves to be mesotroph and eumesophyt.

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