<P> Few species of boreal wildlife are classified under government conservation regimes as being at risk of extinction . However, the decline of some major species of wildlife is a concern . Boreal woodland caribou, whose lichen - rich, mature forest habitat spans the boreal forest from the Northwest Territories to Labrador, is designated as a threatened by the Committee on the Status of Endangered Wildlife in Canada . The Newfoundland population of marten is threatened by habitat loss, accidental trapping and prey availability . </P> <P> The particular mixture of tree species depends upon factors including soil moisture, soil depth, and organic content . Upland forests can be closely mixed with forested peatlands . The resulting conifer forests are produced by and dependent upon recurring disturbance from storms, fires, floods and insect outbreaks . Owing to the accumulated peat in the soil, and the predominance of coniferous trees, lightning - caused fire has always been a natural part of this forest . It is one of many ecosystems that depend upon such recurring natural disturbance . For example, fire dependent species like lodgepole and jack pine have resin sealed cones . In a fire, the resin melts and the cones to open, allowing seeds to scatter so that a new pine forest begins (see also fire ecology). It has been estimated that prior to European settlement, this renewal process occurred on average every 75 to 100 years, creating even - aged stands of forest . Fire continues to cause natural forest disturbance, but fire suppression and clear - cutting has interrupted these natural cycles, leading to significant changes in species composition . </P> <P> Boreal vegetation never attains stability because of interactions among fire, vegetation, soil--water relationships, frost action, and permafrost (Churchill and Hanson 1958, Spurr and Barnes 1980). Wildfires produce a vegetation mosaic supporting an ever - changing diversity of plant and animal populations (Viereck 1973). In the absence of fire, the accumulation of sphagnum peat on level upland sites would eventually oust coniferous vegetation and produce muskeg . </P> <P> Despite today's sophisticated and expensive fire - spotting and fire - fighting techniques, forest fires in Canada still burn, on average, about 28,000 square kilometres of boreal and other forest area annually . That average annual burn area is equivalent to more than three times the current annual industrial timber harvest . It can be many more times that in intense fire years . However, although logging also removes trees, fire is not the same as logging, since fire has been a part of coniferous forests for millennia . Fire not only stimulates regeneration of many plant species, it recycles phosphorus and removes accumulated organic matter . Fire is increasingly used as a management tool to maintain forest health in some parts of North America (see fire ecology). Different parts of the boreal have different burn cycles . The drier western region, which receives lower average rainfall, had higher natural fire frequencies . Hence, more area is burned annually on average in the west than in central and eastern Canada . When natural burn cycles are interrupted by fire suppression, natural renewal is obstructed and species composition is changed . In addition, fire suppression causes fuel loads to increase so that fires, when they do occur, become more intense . One can argue that fire suppression actually creates a positive feed back loop, where ever more expensive fire suppression generates the conditions for ever larger fires . The negative effects of fire suppression are still under study, and not fully measured, but they need to be considered when making decisions about the future health of boreal forests . </P>

Where does the boreal forest start and end