Report - ICP Forests

4. National Survey Reports in 2009 113
same percentage compared to the year before. The percentage of moderately and severely
defoliated Betula spp. trees was 30.8%, representing a decrease compared to the year before.
Betula spp. and Picea abies had the same percentage of trees with severe defoliation in 2009
with about 4.1%, while only 0.8% of Pinus sylvestris had severe defoliation.
In crown discolouration there has been observed a slight improvement for Picea abies from
2008 to 2009 with only 9.6% of the trees showing signs of discolouration. For Pinus sylvestris,
only 2.7% of the assessed trees were discoloured, reflecting a continuous improvement from
2001 when discolouration was as high as 11.3%. For Betula spp., about the same discolouration
was observed in 2009 as in 2008 with 95.3% of the trees having no signs of discolouration.
The mean mortality rate for all species was 0.2% in 2009. The mortality rate was 0.3%, 0.1%
and 0.2% for Picea abies, Pinus sylvestris and Betula spp., respectively. The mortality rate of
Betula spp. was more normal in 2009 and was heavily reduced from the high level of 1-1.8%
which occurred in the tree year period 2006-2008. No serious attacks by pests or pathogens were
recorded.
In general, the observed crown condition values result from interactions between climate, pests,
pathogens and general stress. According to the Norwegian Meteorological Institute the summer
(June, July and August) of 2009 was regarded as relatively warm. The mean temperature for the
whole country was 0.8°C above normal, and the precipitation was 110% of the normal for these
months. There are of course large climatic variations between regions in Norway.
4.20 Poland
In 2009 the survey was carried out on 1 923 plots. Forest condition was almost at the same level
as in the previous year. 24.1 % of all sample trees were without any symptoms of defoliation,
indicating a decrease by 0.3 percent points compared to 2008. The proportion of defoliated trees
(classes 2-4) decreased by 0.3 percent points to the current level of 17.7% for all trees. The
share of trees defoliated more than 25% decreased by 0.2 percent points for conifers and by 0.5
percent points for broadleaves.
22.6% of conifers were not suffering from defoliation. For 17.2% of the conifers, defoliation of
more than 25% (classes 2-4) was observed. With regard to the three main coniferous species,
Picea abies remained the species with the highest defoliation and indicated a slight worsening
especially in older stands. A share of 22.6% (22.3% in 2008) of spruce trees up to 59 years old
and 32.3% (28.5% in 2008) of spruce trees 60 years old and older was in defoliation classes 2-4.
27.3% of the assessed broadleaved trees were not defoliated. The proportion of trees with more
than 25% defoliation (classes 2-4) amounted to 18.6%. As in the previous survey the highest
defoliation amongst broadleaved trees was observed in stands of Quercus spp. and indicated a
slight worsening in older stands. In 2009, a share of 17.4% (17.7% in 2008) of oak trees up to
59 years old and 37.1% (34.9% in 2008) of oak trees 60 years old and older was in defoliation
classes 2-4.
In 2009, discolouration (classes 1-4) was observed on 0.8 %of the conifers and 1.1% of the
broadleaves.