The Natural Fix?

BOREAL FOREST

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.

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.

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