The southern Siberian rainforest is primarily located within the Altai and Sayan mountain ranges across a range of elevations. Geographic features that the forest extends onto include high mountains and ridges as well as valleys carved by glaciers and river basins. The forest-steppe ecotone occurs at elevations as low as 250 to 300 metres while the forest-tundra boundary is between 1600 and 1800 metres. The Katun and Biya Rivers, two tributaries of the Ob River that originate in the Altai Mountains, flow through the region.
Flora
Flora in the region represent a combination of species from four biomes: taiga, сool-temperate forests, tundra and steppe and are more diverse than flora of many of the surrounding areas. The trees include a mix of coniferous and broadleaf tree species. These include Scots pine, silver birch, Eurasian aspen, Siberian pine, Siberian fir, Siberian spruce and Siberian linden. The hemiboreal zones are dominated by Scots Pine and silver birch in wet areas. Moss cover is present, but sparse. Dry areas are dominated by either Scots pine or Siberian larch depending on temperature. Siberian larch is typically more prevalent in cooler areas while warmer and drier areas favor Scots pine. Siberian larch also dominates the forest-steppe ecotone. Epiphyte species include multiple genera of lichen. These include nitrophyte genera such as Physcia and Melanelia, acidophytes such as Usnea and Bryoria and other genera including Hypogymnia and Sticta. Understory plants include Eurasian baneberry, European wild ginger, Baikal anemone, golden saxifrage, bittercress and grasses of the genera Carex, Brachypodium and Calamagrostis.
Fauna
Terrestrial animals in the region include brown bears, European adders, moles of the Talpa genus, red foxes and red deer, gray wolves, lynx, mountain hares, and several species of mustelids including stoats and wolverines. Bird species include hazel grouse, tree pipits, Eurasian three-toed woodpeckers, golden eagles, peregrine falcons, black storks, northern eagle owls, and gyrfalcons. Aquatic species include moor frogs, Siberian taimen, fish of the genus Cottus, Siberian grayling, Asiatic trout and European otters. Insect fauna include the Siberian silk moth, a plant-eating insect species that lives in the region and feeds on tree leaves.
Climate
The climate in the Siberian temperate forest is continental and humid along the Altai and Sayan mountain ranges. Winter temperatures can be as low as -19 degrees Celsius and summer temperatures can reach as high as 17 degrees. The region primarily gets precipitation from Atlantic air masses brought in by westerly winds. The climates are more moderate nearby Teletskoje lake and Baikal. Lake Baikal has the effect of cooling incoming air as it reaches the Khamar-Daban Mountains. The incoming air is forced over the mountains, causing moisture to precipitate out. This causes greater annual precipitation in this area than in the surrounding regions, and can exceed 1500 millimeters annually in some places. In addition, relative humidity can average as high as 75% on an annual basis. The region also loses more water to evapotranspiration than surrounding areas. Current climate change projections predict that local temperatures will increase, causing the forest to expand into nearby alpine tundra areas. Climate change is also expected to result in decreased precipitation in the region.
Threats
Conifer trees in the region have been industrially logged, sometimes illegally, for more than a century. Clear cutting was particularly common with Siberian pine, which was seen as particularly valuable. The removal of these trees is a cause of increased soil erosion due to a lack of roots. Fire also is a disturbance that is most common in areas with Scots pine stands and is expected to increase in frequency as temperatures rise due to climate change. Forest regeneration in these areas is hindered by the faster growth and spread of grasses, particularly the genus Calamagrostis. Insect outbreaks are a threat to many of the tree species in the region. One example of this type of disturbance is the Siberian silkmoth, a species of moth that eats the leaves and needles of broadleaf and coniferous trees respectively. Its most recent outbreak was in 2002. Tree mortality from insect outbreaks and fungal infestations further increases the risk of forest fires due to the increase of combustible material from dead trees, including the trunks which can act as ladder fuel.
