A green Arctic tundra? Study suggests it's possible
Soils in high latitude regions contain more carbon than the atmosphere. With the planet sustaining increasing temperatures, it is important to remember that the Arctic is also feeling the heat. Investigating the potential effects of global warming on the Arctic tundra, researchers in the United Kingdom have discovered that carbon stored in the tundra could be released into the atmosphere by new trees growing in the warmer region. The result? Increasing climate change. The finding of the study is presented in the journal Nature Climate Change.
A warmer climate offers a prime breeding ground for a greener Arctic. Scientists thought that a greener area would mean more carbon dioxide (CO2) would be absorbed from the atmosphere, which in turn would mitigate global warming. But this latest study suggests the opposite is true. If decomposition rates in soils increase, the forest can be expanded into the tundra in arctic Sweden, and in turn trigger the release of CO2 into the atmosphere.
Lead author Dr Iain Hartley, formerly of the University of Stirling in the United Kingdom and now with the University of Exeter, says: 'Determining directly how carbon storage is changing in high-latitude ecosystems is very difficult because the majority of the carbon present is stored below ground in the soils. Our work indicates that greater plant biomass may not always translate into greater carbon storage at the ecosystem level.'
What the team must do now, he says, is increase their understanding of how anticipated changes in the distribution of various plant communities in the Arctic impact the decomposition of extensive carbon stocks in tundra soils. This would help them forecast how the region's greening could affect CO2 uptake or release in the years to come.
The team measured carbon stocks in vegetation and soils between tundra and birch forest. The researchers identified that the two-fold greater carbon storage in plant biomass in the forest was more than outweighed by the smaller carbon stocks in forest soils. They also discovered that birch trees seemed to be stimulating the decomposition of soil organic matter. So they successfully uncovered a mechanism by which the birch trees can contribute directly to reducing carbon storage in soils.
Co-author Dr Gareth Phoenix from the Department of Animal and Plant Sciences at the University of Sheffield said: 'It shows that the encroachment of trees onto Arctic tundra caused by the warming may cause large release of carbon to the atmosphere, which would be bad for global warming. This is because tundra soil contains a lot of stored organic matter, due to slow decomposition, but the trees stimulate the decomposition of this material. So, where before we thought trees moving onto tundra would increase carbon storage it seems the opposite may be true. So, more bad news for climate change.'
The finding makes one consider that colonisation by productive, high-biomass, plant communities in the Arctic may not always result in greater capture of CO2. Rather, net losses of carbon are likely if decomposition of the large carbon stocks in Arctic soils is stimulated.
Related stories: 34698
Data Source Provider: Nature Climate Change; University of Exeter
Document Reference: Hartley, I.P., et al. 'A potential loss of carbon associated with greater plant growth in the European Arctic,' Nature Climate Change, 2012. doi:10.1038/nclimate1575
Subject Index: Climate change & Carbon cycle research; Coordination, Cooperation; Environmental Protection; Scientific Research