Low annual temperatures characterize northerly latitudes; precipitation ranges from 40-100 centimetres per year and may fall mainly as snow.
This combination, along with nutrient poor soils - largely a result of permafrost and the resultant poor drainage - favors the preponderence of conifer species (Abies, Picea, Larix, and Pinus), although species of deciduous trees are also rather common: Betula spp. and Populus spp. Ground cover in Boreal Forests and Taiga is dominated by mosses and lichens.
Low levels and variation of species richness and endemism are characteristic of circumboreal and circumpolar ecoregions, thus the presence of intact ecological phenomena selected outstanding ecoregions.
Large-scale migrations of caribou, or reindeer (Rangifer tarandus) and intact predator assemblages can still be found in some regions, as well as relatively unaltered natural disturbance regimes. For example, the Northern Cordillera boreal forests of Canada have been identified as the "Serengeti" of the Far North due to its abundance and diversity of large vertebrates.
Extensive tracts of boreal forest and taiga still exist in the northern Nearctic and Palearctic, the largest expanses being in central and eastern Russia.
Most species tend to have widespread distributions; low alpha and beta diversity.
Large natural landscapes of taiga are critical to maintain populations of species that track resources that vary considerably in space and time (e.g., epizootic insect events, hare irruptions), viable populations of large carnivores require extensive natural areas because of large home range sizes; disturbance events such as fire and epizootics can cover extremely large areas - even whole landscapes; fire and epizootic events required for some successional processes; large-scale linkages of natural habitat are required to permit migrations of larger vertebrates and associated predators in response to seasonal changes or disturbances.
Sensitivity to Disturbance
Regeneration of mature forests takes very long periods of time due to the challenging climate and soil conditions; many larger vertebrates are sensitive to human presence or low intensity hunting; very sensitive to acid rain and other forms of pollutants.