The Natural Fix?

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.

Tundra ecosystems are dense in carbon. They have little potential to gain more carbon

but a huge amount could be lost if the permafrost were to thaw. Prevention of climate

change is currently the only failsafe method of minimising this loss.

Tundra ecosystems are found in Arctic and mountainous en-

vironments, particularly in Northern Canada, Scandinavia and

Russia, Greenland, and Iceland. Temperatures are low or very

low for most of the year with prolonged periods of snow cover

and a short growing season. The active layer of soil, near the

surface, tends to be waterlogged in summer and frozen in win-

ter. Diversity of plants and animals is low. The environment

selects for slow-growing hardy plants with low biomass above

ground. Rates of decomposition are low and large amounts of

dead plant material accumulate in the soil (approximately 218

t C per ha, Amundson 2001). The slow decomposition rate

means that nutrient recycling is also slow, providing a further

limitation on plant growth and leading to tundra plants al-

locating most of their biomass below ground (De Deyn

et al.

2008). Total plant biomass is estimated to average 40 t C per

ha (Shaver

et al.

1992).

Below the active soil layer is a perennially frozen layer known as

permafrost. Although it is difficult to estimate it is believed that

carbon storage in permafrost globally is in the region of 1600 Gt,

equivalent to twice the atmospheric pool (Schuur

et al.

2008).

HUMAN IMPACTS AND IMPLICATIONS FOR

CARBON MANAGEMENT

At present, tundra ecosystems are little used by humans and there

is also little potential for more carbon capture here under current

conditions. However, even a relatively small amount of global

warming is expected to have major impacts on these systems.

Schuur

et al.

(2008) estimate thawing of the permafrost as a con-

sequence of climate change and subsequent decomposition of soil

carbon could release 40 Gt CO

into the atmosphere within four

decades and 100 Gt CO

by the end of the century, enough to pro-

duce a 47 ppm increase in atmospheric CO

concentration.

TUNDRA