Location and General Description
The Altai-Sayan montane coniferous forest constitutes the mid-elevation part of the Altai-Sayan, the highest mountain system in Siberia. Its contact position between the Siberian taiga and the Mongolian steppe, along with its mountain relief, explain the high diversity of flora and fauna (Mil'kov 1977, Ogureva 1980). The climate is strongly continental, being influenced by the Mongolian center of high barometric pressure. Winters are very cold, while summers are warm. The absolute minimum and maximum annual temperatures at three weather stations are, Katun’ (-50° to +30°C), Olenja Rechka (-43° to +31°C), and Tuva (-58° to +30°C). The mountain relief gives rise to a high diversity of microclimate conditions and temperature inversions. The Altai Mountains are a powerful condenser of atmospheric humidity coming from the west, while the east of the ecoregion (Sayan mountains) receives much less precipitation. The region remains seismically active (Alpatiev et al. 1976).
The Altai-Sayan is dissected by deep river valleys. The Ob, Irtysh and Enisey rivers and their numerous tributaries have their headwaters here (Alpatiev et al. 1976, Mil'kov 1977). According to forest regionalization, this ecoregion belongs to Altai-Sayan Mountain Taiga Province. The forest zone is situated below a sparse forest-subalpine zone and divided into three subzones: light needle-leaf sparse taiga, dark needle-leaf taiga, and black taiga.
The light needle-leaf sparse taiga dominates above 1400 m and forms an open canopy of Larix sibirica with some Pinus silvestris and well-developed shrub and grass layers. The grass layer includes: Milium effusum, Aconitum barbatum, A. volubile, Heracleum sibiricum, Calamagrostis epigeios, C. arundinacea, C. macilenta, and C. obtusata. This elevation belt reaches 1800 m, although the share of Pinus silvestris grows upward, and between 1500 and 1600 m in elevation it sometimes forms almost clear canopies replacing Larix sibirica. Most of these forests are older than 150 years. Common in the shrub layer are Betula nana and Rhododendron parvifolium (Alpatiev et al. 1976, Krasnoborov 1976, Ogureva 1980, Zelenaja kniga Sibiri 1996, Pavlov et al. 1999). In the dark needle-leaf taiga, Abies sibirica is a dominant species together with Pinus sibirica and Picea obovata, and sometimes, Larix sibirica. Sphagnum spp. and lichens dominate on the ground.
The lower border of the forest zone of the Altai-Sayan Mountains lies at varying elevations of 600 to 900 m depending on other environmental parameters. The black taiga has almost the same dominants in the canopy as in the dark needle-leaf taiga (a new common species is Populus tremula), but has a more-developed vertical structure and higher diversity of species. In the shrub layer are found: Padus avium, Viburnum opulus, Lonicera altaica, Caragana arborescens, C. frutex, Spiraea media, S. chamaedryfolia, Rosa acicularis, R. spinosissima, Sorbus aucuparia, Sambucus racemosa, Ribes nigrum, Rubus idaeus and Rosa oxyacanta. Large gaps are common in the canopy and herbaceous vegetation reaches 120 cm and more. Aconitum excelsum, Actaea erythrocarpa, Allium victorialis, Athyrium crenatum, A. filix femina, Calamagrostis obtusata, Cerastium pauciflorum, Crepis lyrata, Dryopteris austriaca, D. filix mas, Festuca gigantea, and Poa remota occupy these gaps. Tertiary relicts include: Asarum europaeum, Stachys sylvatica, Dryopteris filix mas, and Festuca gigantea.
These montane coniferous forests have a high diversity of natural communities and species. Forest flora of the ecoregion consists of about 800 species. Composite in its structure and floristically diverse, black taiga represents the oldest coenotic relict of the dark-needle-leaf forests from the Paleocene and Neogene. It is characterized by the domination of Abies sibirica, Pinus sibirica, and Populus tremula in the canopy, a tall herbaceous layer with a number of relict species, domination of nemoral species and rich ephemeroid flora. The latter two features make it similar with coniferous-broadleaf forests of European Russia and the Far East of Siberia. Twenty-two species are recognized as relicts. The moss layer is not well-developed, but still has high species diversity and absence of common boreal species that are typical for other dark needle-leaf taiga communities. Thirty-four moss species are recognized as relicts. In the black taiga, soils are rich and biological turnover rate is high. This leads to absence of a litter layer on the soil surface.
There are few isolated geographical centers of these relict communities in the Altai, East Sayan and the Chamar-Daban Mountains. Nemoral Atlantic relicts include: Asarum europaeum, Actaea spicata, A. erythrocarpa, Zerna benekenii, Campanula trachelium, Circaea lutetiana, Brachypodium silvaticum, Festuca silvatica, F. gigantca, Geranium robertianum, Stachys silvatica, Sanicula europaea, Epilobium montanum, Dryopteris filix mas, and D. fegopteris. Nemoral Eurasia relicts include: Carex silvatica, Polystichum braunii, Cardamine impatiens, Lislera ovata, and Asperula odorata. There are some relicts of the ancient Mediterranean group such as: Brunnera sibirica, Galium krylovii, and Dentaria sibirica (Krasnoborov 1976, Ogureva 1980, Zelenaja kniga Sibiri 1996). Some habitats of the nationally threatened species include Cypripedium calceolus, C. macranthon, Epipogium aphyllum, and Dactylorhiza fuchsii are protected (Malyshev 1980, Tahtadjan 1981, Zelenaja kniga Sibiri 1996, Pavlov et al. 1999; Zelenaja kniga Sibiri 1996; Tahtadjan 1981; Malyshev 1980).
Common mammals include: Ursus arctos, Gulo gulo, Mustela erminea, Martes zibellina, Alces alces, Mustela sibirica, Capra sibirica, Moschus moschiferus, Capreolus capreolus, Canis lupus, Vulpes vulpes, Talpa altaica, and Sciurus vulgaris. Areas close to the steppe are inhabited by Cervus elaphus. Common birds include: Tetrao parvirostris, Tetrastes bonasia, Cuculus canoms, Picoides tridactylus, Anthus trivialis, Picoides tridactylus, Buteo buteo, Accipiter gentilis, and Accipiter nisus. Common fishes include: Naemacheilus barbatulus, Phoxinus phoxinus, Cottus poecilopus, Cottus sibiricus, Hucho taimen, and Brachymystax lenok. Species listed as threatened are: Coregonus lavaretus pidschian, C. l. pravdinellus, Oreoleuciscus potanini, and Thymallus spp. Common amphibians and reptiles include: Lacerta vivipara, Rana arvalis, Agkistrodonhalys sp., Vipera berus and Agkistrodon halys. Threatened at the national level are: Aquila chrysaetos, Haliaeetus albicilla, Haliaeetus leucoryphus, Faico peregrinus, Pandion haliaetus, and at the oblast level: Buteo hemilasius, Pemis ptilorhyncus, and Accipiter gularis. Common owl species include: Asio flammeus, and Otus scops. Owl species considered rare include: Bubo bubo, Strix nebulosa, Strix uralensis, Asio otus, Sumia ulula, Glaucidium passerinum and Aegolius funereus (Yudin et al. 1979, Pavlov et al. 1999;).
Ecosystems of the montane forest are significantly disturbed. Light needle-leaf forests of lower elevations are almost completely clearcut. Nevertheless, some large tracts of forests are protected either by their difficulty of access or by law. The latter ones include Altajskij, Sajano-Shushenskij, Azas and Ubsunurskaja Kotlovina Zapovedniks, Ubs Nuur Basin and Hordil Saridag Strictly Protected Areas, and Huvsgol National Park. However, being designated for protection does not guard all the diversity of forest communities. Small-leaf forests dominated by birch and aspen replace most of the clearcut forests.
Types and Severity of Threats
Modern techniques of forest harvesting have led to significant slope erosion and eutrophication of water ecosystems. Poaching poses a serious threat for some fauna species. Transregional pollution from Russia, Kazakhstan and China bring some highly toxic pollutants into the ecoregion (Alpatiev et al. 1976, Yudin et al. 1979, Pavlov et al. 1999).
Justification of Ecoregion Delineation
Ecoregion boundary delineation in Russia is based on Kurnaev’s (1990) map of forest zones. It includes Kurnaev’s southern and northern taiga zone and the extreme southern highlands of Western Siberia and northeastern region of Tuva-Buryat-Mongolia vegetation province. It also encompasses the taiga forest in north central Mongolia according to Hilbig (1995) and the Mongolia Ministry for Nature and Environment (1996). Both Altai and Sayan montane coniferous forests are considered a single center of plant diversity according to Davis et al. (1995). However, their patterns of plant richness and endemism are quite distinct.
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Prepared by: Chris Carpenter
Reviewed by: Batbold D. Otgoid