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Tundra
Boreal forest
Temperate forest
Temperate grasslands, savannas and shrublands
Desert and dry shrublands
Tropical and subtropical forests
Tropical and subtropical grasslands, savannas and shrublands
Source: adapted from Olson
et al
., 2001.
The boreal forest biome holds the second largest stock of carbon; most of this is stored in the
soil and litter. The draining of boreal forest peatlands, inappropriate forestry practices and poor
fire management may all cause significant losses of the carbon stored in this ecosystem.
Boreal forests occupy large areas of the northern hemisphere
and are mainly found in Canada, Russia, Alaska and Scandina-
via. Biodiversity in these forests is generally low. Plant biomass is
much higher than in the tundra, with roughly 60–100 tonnes of
carbon per hectare, of which around 80% is in the above-ground
biomass (Mahli
et al
. 1999; Luyssaert
et al
. 2007). Because of the
low temperatures, decomposition in boreal forests is slow. This
leads, as in the tundra, to large accumulations of carbon in the
soil pool (116–343 t C per ha, Mahli
et al
., 1999; Amundson 2001).
Fire is common in boreal forests and is one of the main drivers
of the carbon balance here, with carbon being lost from the sys-
tem when fire frequencies are high (Bond-Lamberty
et al
. 2007).
There is debate about whether the very mature old-growth boreal
forests are currently a carbon source or a carbon sink, though
recent studies suggest that these old-growth forests may indeed
be carbon sinks (Luyssaert
et al
. 2008). In general, due to the low
decomposition rates and the extensive peatlands they can grow
on, boreal forests are considered to be important carbon sinks.
HUMAN IMPACTS AND IMPLICATIONS FOR
CARBON MANAGEMENT
Increasing human pressure on these forests, through logging
and mining, and the draining of the peatlands these forests
grow on, releases carbon to the atmosphere and significantly
reduces their carbon storage capacity. Protection of boreal for-
ests against logging and implementing best forestry practices
may therefore reduce carbon emissions, sustain carbon stocks,
and maintain uptake by these forests.
BOREAL FOREST