Forest Condition in Europe - ICP Forests

86 Forest Condition in Europe 2013
For birch, the observed trees in the most serious class ‘Severely discolouration’ were only 0.2
% in 2012 compared with 3.3 % in 2011!
The mean mortali
ty rate for all species was 0.2 % in 2012. The mortality rate was 0.2 %, 0 % and 0.3 % for
spruce, pine and birch, respectively. The mortality rate of birch has been more normal the last
four years and is heavily reduced from the high level of 1-2 % which occurred in the tree year
period 2006-2008 probably due to serious attacks of insects and fungi.
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 2012 was regarded as about normal. The temperature was
0.4 ºC less than normal, and the precipitation was 5 % more than normal as an average for the
whole country. In south-east Norway, where summer drought is a frequent problem for trees,
however the precipitation in 2012 was 40 % higher than normal. The highest precipitation in
south-east Norway was in 2011 with 95 % higher than normal, and the second highest was in
1950 with 65 % higher than normal. There are of course large climatic variations between
regions in Norway which range from 58 to 71 ºN.
6.7. Poland
In 2012 the forest condition survey was carried out on 1965 plots.
Forest condition (all species total) remained slight deterioration as compared to the previous
year. 11.3% (14.0% in 2011) of all sample trees were without any symptoms of defoliation,
indicating a decrease by 2.7 percent points compared to 2011. The proportion of defoliated
trees (classes 2-4) decreased by 0.6 percent points to an actual level 23.4% of all trees. The
share of trees defoliated more than 25% decreased by 2.0 percent points for conifers and increased
by 2.0 percent points for broadleaves.
8.7% of conifers were not suffering from defoliation. For 22.2% of the conifers defoliation of
more than 25% (classes 2-4) was observed. With regard to the three main coniferous species
Abies alba remained the species with the lowest defoliation (18.92% in 2-4 classes), although
indicated a worsening comparing to previous year. A share of 21.8% (17.3% in 2011) of fir
trees up to 59 years old and 18.3% (16.1% in 2011) of fir trees 60 year old and older was in
defoliation classes 2-4. The highest defoliation was observed in Picea abies (29.8% indicated
a worsening comparing to previous year. A share of 24.8% (23.4% in 2011) of spruce trees up
to 59 years old and 33.2% (28.1% in 2011) of spruce trees 60 year old and older was in defoliation
classes 2-4.
16.1% of assessed broadleaved trees were not defoliated. The proportion of trees with more
than 25% defoliation (classes 2-4) amounted to 25.5%. As in the previous survey the highest
defoliation amongst broadleaved trees was observed in Quercus spp indicated deterioration in
older stands. In 2012 a share of 28.2% (28.0% in 2011) of oak trees up to 59 years old and
42.9% (32.2% in 2011) of oak trees 60 years old and older was in defoliation classes 2-4.
Fagus sylvatica remained the broadleaves species with the lowest defoliation, indicated slight
improvement in older stands. A share of 10.2% (9.8% in 2011) of beech trees up to 59 years
old and 9.22% (11.8% in 2011) of beech trees 60 year old and older was in defoliation classes
2-4.
In 2012, discolouration (classes 1-4) was observed on 1.5 % of the conifers and 1.8 % of the
broadleaves.