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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