Researchers in Finland working on a comprehensive model of the carbon cycle
Researchers in Finland are working to develop a comprehensive, multidisciplinary model of the carbon cycle and its impacts on climate change in northern ecosystems. The focus of work in the Academy of Finland’s Global Change Research Programme (FIGARE) has been on the uptake and release of carbon in different ecosystem reservoirs, the atmosphere, vegetation, trees, forest land and lakes.
‘The carbon dioxide content in the earth’s atmosphere is slowly and steadily increasing. Given the results we have accumulated over the years using highly accurate instruments that measure carbon dioxide flows, it is now possible by means of meteorological methods to establish what kinds of sinks and sources there are for carbon dioxide, to know where carbon dioxide is stored and where it is released from,’ says Professor Timo Vesala from the University of Helsinki.
In Finland, atmospheric carbon dioxide is regularly monitored among other things by means of point measurements in forest environments. This method yields local information on how much carbon dioxide is stored in forests and how much is in turn released. ‘This is important and valuable information even though it sheds no light on the bigger picture of carbon exchange. It is used by researchers to try and model and predict the process of carbon exchange in the forest ecosystem. The model we are now working on will be useful if it can predict factors that have an impact on the carbon cycle in different weather conditions,’ Professor Vesala continues.
There is extensive international cooperation in the field of carbon dioxide measurement, with similar measurement stations dotted around the globe from tropical regions up to the far north. ‘Climate change will be reflected in the way that forests function, but we do not yet know whether trees will be storing more or less carbon dioxide than they do at the moment,’ says Professor Vesala.
Forest trees and soil effectively store carbon
The standing tree stock and forest land in Finland are major reservoirs of carbon. In Finnish forests the carbon reserves in the mineral soil layer 40 centimetres in depth amount to an average 5.52 kg per square metre, the nitrogen reserves stored in the whole mineral soil layer 20 cm in depth amount to 0.17 kg per square metre. Based on these average data collected by the Forest Research Institute from its 488 permanent sample areas, preliminary estimates of the total carbon reserves in Finnish forests stand at 921 megatonnes, for nitrogen reserves the figure is 26 megatonnes.
The amount of carbon stored in standing trees is considerable. In the Forest Research Institute’s sample areas the carbon reserves were within the range of 6.8-24.4 kg per square metre. The exact size of the carbon reserves in this case obviously depends closely on the age of the standing tree stock.
‘We found in our studies that within 12-27 years of clear-cutting, the size of the carbon reserves in the soil increased on average by half a kilogramme per square metre. If this observation is supported by further studies, this will have significant implications for instance with regard to carbon budget calculation and further negotiations around the Kyoto Protocol,’ says Docent Hannu Ilvesniemi from the University of Helsinki. He points out that the soil is a highly effective reservoir of soluble carbon. Logging waste increases the carbon dioxide flow from the soil into the atmosphere, but this is a relatively short-term effect.
Biggest emissions from shallow and eutrophic lakes
Researcher Pirkko Kortelainen from the Finnish Environment Institute says it is reasonable to assume that Finland’s lakes are highly significant sources and sinks of carbon: there are more than 56,000 lakes in the country larger than one hectare in size, with a total shoreline of 140,000 kilometres and covering ten per cent of the country’s surface area.
‘Studies by the Geological Survey of Finland and the Finnish Environment Institute indicate that a total of 700-900 million tonnes of carbon is stored the country’s lake sediments. This represents the third biggest carbon reservoir in Finland after bogland and forests,’ Pirkko Kortelainen says.
At the same time carbon dioxide and methane are continually released from Finland’s lakes into the atmosphere. There is considerable regional and seasonal variation in the level of gas emissions from around the shores of lakes. Increasing lake eutrophication causes methane emissions to rise. Crucial background variables include temperature, sediment properties as well as the type of flora around the shores. Emissions tend to be highest in areas where plants (such as the common reed) are capable of regulating their gas exchange
Pirkko Kortelainen has discovered in her research that, measured by surface area, carbon reserves as well as gas emissions from open lake areas are biggest in small, shallow lakes. Sedimentation and the breakdown of organic matter in lakes upstream reduce the carbon reserves and gas emissions in lakes downstream. Average annual carbon dioxide emissions out on open lake areas turned out to be several times higher than the permanent annual accumulation in sediments. This suggests that lakes play a highly significant role in breaking down the carbon washed down from terrestrial ecosystems as well as in releasing greenhouse gases.
FIGARE studied the impact of human action on environmental change and the impact of environmental change on humans
Funded by the Academy of Finland, the three-year Global Change Research Programme (FIGARE) set out to analyse and increase our understanding of the changes taking place in the global system as well as the underlying causes and impacts of those changes. Furthermore, the programme has been concerned to find effective ways of intervening in and adapting to the changes underway.
Global change refers to all those changes that are taking place in the natural environment as a consequence of either natural processes or human activity as well as to the separate and combined effects of these changes on society and the economy. A proper understanding of the causes and effects of global change requires a research effort which takes in the natural sciences, the social sciences, economics and technology. The most important aspect of global change is that of climate change: the impacts of climate change are universal, but they also have various effects on industries, the social structure and indirectly on all facets of social life.
Due to be completed during the course of the present year, the FIGARE programme served as an umbrella for a total of 36 research projects. Funding from the Academy of Finland totalled EUR 4.2 million. In addition funding was provided by the Ministry of Trade and Industry, the Ministry of Transport and Communications, the Ministry of Agriculture and Forestry, the Ministry for Foreign Affairs, the Ministry of the Environment and the National Technology Agency Tekes. Total funding amounted to close on EUR 7 million.
The Research Programme’s final scientific congress under the heading ”Understanding the Earth system – the Finnish perspective” will be held at Hanasaari Cultural Centre, Espoo,Finland, on 9-10 December 2002. All research projects will be taking part and presenting their results. In addition, some of the top international names in research on global change have been invited to attend.
Jenni Järvelä | alfa