Taiga or Boreal Forest
The boreal forest is a continuous belt of vegetation at high latitudes that stretches from the Atlantic shoreline of central Labrador, westward across Canada to the mountains, interior and central coastal plains of Alaska.
It transitions to the tundra to the north.
Lower latitude transitions:
Subalpine forests of Alberta and British Columbia to west
Prairie grasslands to southern interior
Great Lakes/St. Lawrence mixed forest to southeast
Diversity is low
Picea glauca (white spruce) and P. mariana (black spruce) ubiquitous
Also: larch, balsam fir, jack pine, lodgepole pine
Deciduous: balsam poplar, paper birch, aspen
Cool, humid, with very cold winters
There is more precipitation than is needed for evapotranspiration
Lichen woodlands are a characteristic feature
May follow fire, or may actually be a climax community
Characteristic of the northern part of the Taiga
Weber, M.G. and B.J. Stocks. 1998. Forest fires and sustainability in the boreal forests of Canada. Ambio 27(7):545-550.
Fire and boreal forest ecology
Fire may have been an integral part of the ecology of this system as long ago as the Miocene or Pliocene (30-12 million years BP)
By the end of the last glaciation (15 thousand years BP), species adaptations and successional pathways were fully developed.
Climax is the culmination of forest succession.
It results in a self-perpetuating state
Strict application of this ecological concept to boreal forests is difficult
Fire is ubiquitous
Species are adapted to its regular occurrence.
Typical forest before fire is composed of jack pine, black spruce, paper birch and aspen.
After fire, recolonization is immediate, and with mostly the same species.
Jack pine would disappear without fire.
Serotinous cones require fire to open
Seed needs bare mineral soil to germinate
Seedlings need absences of canopy to grow
Similar, but less exacting, requirements.
Other fire role
Creates a landscape mosaic
This supports plant and animal biodiversity
Fire burns in a patchy way
Return intervals and intensities are variable
Parks Canada in 1988 began reversing years of fire suppression by doing prescribed burns.
Apparently anthropogenic burning started when the land to the east of the Bering land bridge was settled 12,000 years BP
Kuuluvainen. T., et al. 2002. Principles of ecological restoration of boreal forest ecosystems: Finland as an example. Silva Fennica 36(1):409-422.
Natural forest dynamics are still dominant over much of the boreal forest in Canada and Russia, but in southern Scandinavia the forests have been heavily harvested and are now mostly managed systems.
Conservation values of managed systems can be improved by modifying silvicultural techniques.
Recommendations of Finish Ministry of Environment:
Need additional conservation of rare forest types
Herb-rich forests, spruce mires
Restore forests both within protected areas and in managed areas around them
Increase conservation lands around core areas
Use bio-diversity oriented silvicultural methods
Management changes in practice:
Setting aside special habitats (key biotopes)
Retaining living and dead trees when harvesting
(These all add structural features of natural forests to managed forests)
Most restoration in Finland has focused on drained peatlands
Filling ditches to restore hydrology
Removing trees planted in open mires
On mineral soil
Creates dead wood and starts succession
Girdling and felling
Imitating gap dynamics with openings in even-age stands.
Weber, M.G. and M.D. Flannigan. 1997. Canadian boreal forest ecosystem structure and function in a changing climate: impact on fire regimes. Environ. Rev. 5:145-166.
Boreal forest fire regime is an organizing factor of boreal forest landscapes
It includes fire intensity, frequency, seasonality, size, type (crown versus surface), and severity (depth of burn).
It is highly dependant on climate.
Models point towards unprecedented increased regional or seasonal temperatures
Projected changes most pronounced at high latitudes and there greatest in winter
Changed fire regimes could result in increased annual area burned because of an extended
fire season, increased fire frequency, and severity.
There is potential for greatly reduced boreal forest area and increased fragmentation
Fire regime as an ecosystem process is highly sensitive to climate change because fire behavior responds immediately to fuel moisture, which is affected by precipitation, relative humidity, air temperature and wind speed.
This indirect effect of climate change has the potential to overshadow the direct effects of global warming on species distribution, migration, substitution, and extinction