We present the results which we obtained through detailed ecological and silvicultural-geobotanical investigations into the northernmost massif of sparse subtundra larch forests within the Lena river basin in Tit-Ary Island (territory of the Bulunskii district, Sakha (Yakutia) Republic) for the period from 2009 to 2014 as part of an integrated expedition of the Institute of Biological Problems of the Permafrost Zone SB RAS. Tit-Ary Island is one of the largest islands within the Lower Lena basin; it is situated in the river delta. Presented are the data on the present status of the main forest assessment parameters of larch tree stands, and information concerning their dependence on environmental conditions; specifically we emphasize the role of aspect and of the main characteristics of the growth conditions of larch stems in different types of sparse larch forests. Also, the focus is on the role played in the growth processes by soil drainage, and by the character of thawing of frozen ground that influences the thickness of the seasonally thawed layer. A study of the age structure of larch tree stands showed that the modern generation of the main massif of forest vegetation in the island emerged in the middle of the last century. A dramatic increase in the growth of Kajander larch has been observed during the last decade, which is associated with the general climatic changes for the period involved.Keywords: subtundra forests, Kajander larch, ecotope, seasonally thawed layer, sparse forest, tundra with low center polygons.