Baltic Marine Environment Protection Commission - HELCOM
Government of Finland
Request for research and action
Humus discharges from forestry and the state of the Baltic
Sea and Finland’s inland waters
Humus discharges from forestry and the state of the Baltic Sea and Finland’s inland waters
The Finnish Association for Sustainable Forestry calls upon the Baltic Marine Environment Protection Commission and the Finnish government to take note of the impacts of forestry and mire drainage on the state of the inland water system and the Baltic Sea, and to take the measures proposed in this request in accordance with the principle of caution.
The Baltic Sea is the world’s largest basin of brackish water and its ecological equilibrium has been disturbed by excessive concentrations of phosphorus and nitrogen. Since the 1974 Baltic Sea Conference efforts have been made to understand the origins of eutrophication caused by nutrients and how the Baltic Sea can be restored to its former condition. According to the current consensus, the largest sources of environmental nutrient discharges are agriculture and human habitation.
This idea is based on the fact that the nutrient discharges from rivers to the Baltic Sea are well known and that we also know that nutrient discharges cause eutrophication of water systems. Over the last thirty years there has been no public consideration of the simple question of whether nutrient effluents to the Baltic Sea are quantitatively sufficient to cause the present state of eutrophication.
The attached calculations of laboratory engineer Pekka Viherä demonstrate that nutrient discharges are simply insufficient to cause the present situation. There must therefore be some other reason for the eutrophication that has occurred. One possibility is that drainage of Finnish peatland is the main reason for the problems of the Baltic Sea.
More than five million hectares of peatland have been drained in Finland. Within only a few years such drainage operations cause humus discharges on a scale corresponding to the natural leachate of hundreds of years. There can be no question that this has a dramatic impact on the ecological balance of water systems that have only developed to deal with natural loading.
Some of these humus flows are deposited in the bottom sediment of internal waters, while the remainder sinks to the bottom only on reaching the more saline waters of the Baltic Sea. Decomposition of this organic material in turn consumes oxygen near the seabed and causes a state of oxygen depletion, resulting in the release of phosphorus reserves from the seabed sediment. Phosphorus is a critical limiting factor for eutrophication. Viherä’s calculations support the view that the impacts of this chain of events on eutrophication may be even greater than those of discharges from human habitation and agriculture.
In addition to discharges from mire drainage, the Baltic Sea has also received, and continues to receive, massive oxygen-depleting discharges from clear-cutting areas covering thousands of square kilometres of forest in Finland and Sweden. While clear-cutting already increases the rate of discharges to many tens of times the natural leaching rate, the creation of exposed soil further magnifies this effect to a dangerous degree. The vehicles used in summer logging on unfrozen fresh soil also tear up the ground causing further discharges.
Little attention has so far been paid in research and debate to forest and mire drainage or forest management. The Finnish Association for Sustainable Forestry calls on the Baltic Marine Environment Protection Commission to appoint an independent international research team to investigate the impact of humus discharges from forestry on the problem of oxygen depletion in the Baltic Sea and the inland water systems of Finland.
Finland has now embarked on a remedial programme of mire drainage that is releasing humus effluent on the same scale as the original mire drainage programme. It has been publicly claimed that discharges could be limited through the use of settling basins and other special drainage arrangements. The problem period for discharges, however, is the spring flooding season. A thorough investigation should be made into whether the flow of waterborne humus from drained areas can be prevented during the flooding season. There is a major danger that we are now once again releasing organic oxygen-depleting substances from peatland that will have a fatal impact on the Baltic Sea and on the inland waters of Finland. The rate of natural leaching can no longer be increased by forest management measures.
Pursuant to the principle of caution, the Finnish Association for Sustainable Forestry calls upon the government of Finland to take the following measures as a matter of urgency:
1 To suspend new mire drainage projects pending a thorough investigation of humus discharges and their effects.
2 To refrain from clear-cutting and soil cultivation on slopes, in areas with a high density of drainage ditches, and in sufficiently broad shoreline protected areas.