Growth Trends of Forests in Finland and North-Western Russia

Abstract

Several studies concerning growth trends in Finland and north-western Russia are cited in this paper. Many of these studies are from the northern part of the area, close to the Arctic timber line. The forests in that region are especially suitable for trend studies due to strong reactions of tree growth to the environmental changes and lack of competition due to low stand density.

In the North, both negative and positive trends have been found. Local forest growth decline of unusual extent was observed around non-ferrous smelters in the Kola Peninsula, north-western Russia. In addition to the total dieback of forests near the smelters, reduced growth of Scots pine was detected up to 30–35 kilometres away from the sources of pollution.

The area of local forest decline covers only a small fraction of the total forest area around pollution sources. In the major part of forests in Lapland, the radial increment of Scots pine has been at a clearly higher level than in the 19th century. This is mainly due to more favourable climatic conditions in this century, especially in the 1930s. This conclusion is supported by studies conducted in other parts of Finland. The nitrogen deposition, many times higher than in the North, has namely caused no measurable trends in the radial increment of Scots pine in southern Finland.

In the region of Sankt Petersburg in Russia, ageing study stands show no decrease in current annual volume increment during the last few decades. This abnormal behaviour of mature stands can be a sign of increased nitrogen deposition (25 kg ha^-1 annually) or of normal long-term climatic variation.