|Photo: Metla/Erkki Oksanen
Forest condition in national networks (ICP Forests, Level I and Level II)
By Seppo Nevalainen & Martti Lindgren
Metla has carried out the large-scale crown condition survey (Level I) since 1986 (until 2012) and the intensive crown condition survey (Level II) since 1995. The main observed variables have been the degree of defoliation and foliage discolouration and the occurrence of abiotic and biotic damage to Scots pine, Norway spruce and broadleaves. The average tree-specific degree of defoliation for the period 1986–2012 on Level I sites was 10.7% in pine, 19.6% in spruce and 12.8% in broadleaves and for the period 1995–2013 on Level II observation plots 11.3% and 18.2% for pine and spruce, respectively.
The proportion of defoliated trees seems to have increased in the southernmost part of the country. In general, the proportion of discoloured spruces was higher and varied annually much more than that in pine or birch.In Level 1, the proportion of trees with symptoms of abiotic or biotic damage decreased during the monitoring period (1986–2012). The mean proportion of symptomatic trees was the same (60%) in all main tree species groups. Pines had less abiotic and unidentified damage, but more insect damage than spruce and broadleaved species. Level I data provides t emporal patterns and coarse spatial distributions of some of the most common causes of damage. The proportion of dead trees on Level I varied from 0.1 to 0.32%. High stand age, weather and climatic factors, as well as abiotic and biotic damage, have a considerable effect on defoliation in background areas of Finland.
Concern about the largescale decline in forest vitality in Central Europe in the late 1970s and early 1980s led Finland to initiate an extensive national survey of forest conditions. The Finnish Forest Research Institute has surveyed crown conditions annually since 1986. The monitoring has been carried out in co-operation with the UN/ECE ICP-Forests-programme and, during 1995-2006, in accordance with EU regulations. Forest condition monitoring is carried out using international harmonized methods (Eichhorn et al. 2010, pdf).
This report presents a review of the results on forest condition monitoring in Finland. The results of extensive (Level I) and intensive level (Level II) surveys, as well as the annual variation in forest conditions and the regional distributions are presented, together with some interpretation of the apparent factors, which may explain the regional pattern and changes in forest conditions.
Results: Extensive monitoring 1986–2012
Results: Intensive monitoring 1995–2013
Citation: Nevalainen, S. and Lindgren, M. (2014). Forest condition in national networks (ICP Forests, Level I and Level II). In: Merilä, P. & Jortikka, S. (eds.). Forest Condition Monitoring in Finland – National report. The Finnish Forest Research Institute. [Online report]. Available at http://urn.fi/URN:NBN:fi:metla-201405221017. [Cited 2014-05-22].
The 2013 version available at http://urn.fi/URN:NBN:fi:metla-201305087572