The Natural Fix?

TUNDRA

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 2 into the atmosphere within four decades and 100 Gt CO 2 by the end of the century, enough to pro- duce a 47 ppm increase in atmospheric CO 2 concentration.

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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