Forest Condition in Europe - ICP Forests

76 Forest Condition in Europe 2013
From the total number of sample trees surveyed, 68,33% showed signs of insect attacks and
6,94% showed signs of attacks by “other agents, T8” (lichens, dead branches and rat attacks).
Also 6,67% showed signs of both factors (insect attacks and other agent).
The major abiotic factors causing defoliation in some plots, during 2012, were the combination
of the climatic with the edaphic conditions which resulted to secondary attacks by Leucaspis
spp. and defoliator insects, to half of the trees.
5.7. Czech Republic
In the older age category of coniferous species (forest stands at 60 years of age and more)
very moderate deterioration in the development of total defoliation occurred in 2012 compared
to the previous year due to a less pronounced decrease in percent defoliation in class 0
and an increase in percent defoliation in class 1. Norway spruce (Picea abies) with the highest
species representation in this age category (63%) contributed to this change to the greatest
extent. No pronounced changes were observed in the other tree species in this age category
(Pinus sylvestris, Abies alba and Larix decidua). Compared to the previous year, in 2012 the
development of total defoliation was also worse in the younger age category of coniferous
species (forest stands younger than 59 years of age); it was partly much worse than in the older
age category. Spruce also contributed to this change to the largest extent because percent
defoliation in class 0 decreased from 59.9% in 2011 to 53.3% in 2012 while at the same time
percent defoliation in class 1 increased from 29.7% in 2011 to 37.3% in 2012.
The development of total defoliation of broadleaved species in the older age category (forest
stands of 60 years of age and more) showed a moderate improvement due to a decrease in
percent defoliation in classes 1 and 2 and a simultaneous increase in percent defoliation in
class 0. European beech (Fagus sylvatica) contributed to this change to the greatest extent as
its percentage in defoliation class 0 increased from 23.9% in 2011 to 29.9% in 2012 at a simultaneous
decrease in percent defoliation in classes 1 and 2. Only a very moderate improvement
was observed in oak (Quercus sp.). Similarly like in older broadleaves, in younger
broadleaves (forest stands younger than 59 years) there was a moderate decrease in total defoliation
due to a decrease in class 2 defoliation and an increase in percent defoliation in classes
1 and 0. The contribution of beech to this change was also greatest in which its percentage in
defoliation class 0 increased very distinctly from 54.9% in 2011 to 81.6% in 2012 and its percentage
in classes 1 and 2 decreased at the same time. Like in the older category, only a very
moderate improvement was recorded in oak.
Younger coniferous species (less than 59 years) show lower defoliation in the long run than
forest stands of younger broadleaves. In older stands (60 years old and more) this comparison
gives an opposite result: older conifers have pronouncedly higher defoliation than the stands
of older broadleaves. The share of pine of both age categories in higher percent defoliation is
crucial in the group of coniferous species.
A distinct improvement in defoliation of beech stands was caused by the regeneration of
crowns severely damaged by late spring frost in the preceding year. A moderate worsening of
defoliation in coniferous species was probably also influenced by adverse weather conditions.
Average monthly temperatures in the period of March – September were above average compared
to the long-term normal temperatures (deviation in the range of 0.5 – 2.7°) while average
monthly precipitation amount was mostly below average in the same period in this comparison,
reaching 38 – 100% of the normal precipitation (except July with 144%). This ad-