Initially, our LUSTRA research programme focused on studying the potential role of carbon sinks in achieving Sweden´s objective of reducing greenhouse-gas (GHG) emissions. Quite soon, however, carbon sinks were found to play a fairly marginal part, in national terms, in fulfilling Sweden´s commitment to cutting GHG emissions. ‘We thought the soil might mean much more in terms of carbon sequestration. But the question of how we use forest land is much more crucial,´ says Mats Olsson, programme manager for LUSTRA and Professor of Forest Soils at the Swedish University of Agricultural Sciences (SLU) in Uppsala.
LUSTRA (the Swedish acronym for ‘Land-Use Strategies for Reduced Net Emissions of Greenhouse Gases´) has been under way since 1999. Topics studied by the researchers is how various factors affect carbon flows (e.g. how carbon is absorbed through photosynthesis and emitted through decomposition of plant remains) and carbon deposition, and how the forest ecosystem can help to cut atmospheric GHG emissions. Carbon deposition, i.e. how carbon is deposited in vegetation and soil, reduces CO2 concentration in the atmosphere to a corresponding degree.
LUSTRA has developed methods of measuring the quantity of carbon in our soils, and researchers at SLU will continue this work. Under the Kyoto Agreement, one obligation for ratifying countries is to disclose the size of their carbon stocks on an annual basis. Henceforth, SLU will carry out measurements and report the results to the Swedish Environmental Protection Agency, which will in turn report to the United Nations.
SUSTAINABLE PEAT HARVESTING
The programme has also succeeded in showing that carbon stocks in the soil are larger in the South than in the North of Sweden. One probable reason is the greater quantity of nitrogen inSouthern Sweden . Another key result relates to forest peatland and its impact on GHG emissions.
‘Peatlands emit large quantities of carbon dioxide and “laughing gas". One way of boosting carbon sequestration is to use nitrogen fertiliser. On the other hand, it´s harmful in terms of acidification and biodiversity. There are no simple, general solutions. So the problems connected with how we can use land to reduce greenhouse gases have become bigger and more complex,´ says Mats Olsson.
Peatland accounts for 15 per cent of national greenhouse-gas emissions. The key questions are how peatlands could be improved to reduce emissions and whether increasing their productivity is feasible. The solution proposed by Mats Olsson is to harvest the peat before it erodes through oxidation, and only then plant forest trees, because forest sequesters carbon.
Magnus Brandel, CEO of the Swedish Peat Producers Association, thinks that the LUSTRA findings have been directly useful to his Association.
‘Instead of letting the peat “vanish" by simply oxidising away, we propose using it to produce energy. The Energy Agency and the Environmental Protection Agency have recently been commissioned by the Swedish Government to devise criteria for deciding which peatlands should be made more climate-efficient,´ he says.
At present, peat is eligible for the Swedish green electricity certificate. Thus, it is equated with renewable fuels in the national system of electricity certificates.
BALANCING DIFFERENT AIMS
In Mats Olsson´s view, achieving a more balanced view of our peatlands is important.
‘Which peatlands should we use to minimise greenhouse gases, and which should we use to conserve biodiversity? It´s a matter of constantly balancing the need to reduce carbon-dioxide emissions and the need to exploit forest peatland. We can also show that spruce sequesters more carbon in the soil than pine does. Given this result, we could recommend the forest industry to switch to spruce cultivation to a larger extent. But this means changing the tree species, and it will have economic and other environmental consequences. For instance, it may have an adverse impact on biodiversity,´ he says.
‘Perhaps our key message is that, in future discussions, our ways of using land and their purposes must be weighed up against one another.´
One forthcoming task — which the LUSTRA researchers want to tackle — involves this weighing-up of priorities. The question we face is how to use peatlands, taking into account both the economic conditions of forestry and Sweden´s objectives for environmental quality, such as maintaining biodiversity and reducing impact on the climate.
