CLASSIFICATION OF DWARF PINE COMMUNITIES IN THE NORTH OF THE KORYAK DISTRICT (KAMCHATKA TERRITORY)

Abstract

A detailed geobotanical characteristic of Siberian dwarf-pine (Pinus pumila (Pall.) Regel) communities of the north of the Koryak District is presented. The vegetation classification based on 83 relevés has been elaborated using main principles and classification methods of Russian dominant-determinant approach. As the result 10 associations, 10 subassociations and 9 variants classified within 5 association groups were revealed. The peculiarities of their species composition, community structure, ecology and geographical distribution were characterized. Using soil characteristics, several types of sites were recognized. It was shown that mesophytic moss-rich dwarf-pine shrubs (Pinetum pumilae hylocomiosum) were closely connected to the mean values of soil moisture and soil fertility of the sites. Rhododendron-rich dwarf-pine communities (subass. Pinetum pumilae rhododendroso aurei–hylocomiosum) adjoined them but they usually occurred on higher altitudes. Lichen-rich dwarf-pine shrubs (Pinetum pumilae fruticuloso–cladinosum) occupied the driest and poorest sites at the upper border of dwarf-shrub altitudinal belt (350–400 m a.s.l.). The dwarf-shrub-rich Siberian dwarf-pine communities (ass. group Pineta pumilae fruticulosa) were closely connected to rather dry and poor sites. In wet sites with shallow groundwater, Sphagnum-rich dwarf-pine communities (Pinetum pumilae sphagnosum girgensohnii) were found. Cloudberry-rich dwarf-pine shrubs (subass. Pinetum pumilae chamaemori–rubosum) adjoined them but mainly occurred on the peat hillock of palsas. The variation in the species composition and structure of communities are determined by their position in the relief and the density of the dwarf-pine layer. With a similar density of dwarf-pine, Sphagnum-rich dwarf-pine communities form in the foothills, and lichen-rich dwarf-pine shrubs form in mountains. The species diversity and the abundance of the subordinate layers are significantly reduced at the maximum density of the dwarf-pine; so poor-herb dwarf-pine communities (Pineta pumilae oligoherbosa) are formed.