Report - ICP Forests

4. National Survey Reports in 2009 101
The share of not defoliated Fagus sylvatica trees increased from 47.3% in 2008 to 54.6% in
2009. For Quercus spp. the increase was from 43.5% in 2008 to 79.0% in 2009. Some damage
on Fagus sylvatica was caused by Rhynchaenus fagi, Ectoedemia libwerdella, Nectria spp., and
some damage on Quercus spp. was caused by Ceratocystis roboris.
The share of trees showing discolouration decreased in conifers and broadleaves. Abiotic agents
(drought, snow, ice) did not have a negative influence on crown condition of the sample trees.
4.5 Croatia
In the forest condition survey in 2009, 83 sample plots on the 16 x 16 km grid were included.
The percentage of trees of all species within defoliation classes 2-4 (26.3%) in 2009 was higher
than in 2008 (23.9%). For broadleaves as well, the share of trees in classes 2-4 (20.7%) was
higher than in 2008 (19.1%). For conifers, the percentage of trees in defoliation classes 2-4
(66.5%) was higher than in 2008 (59.1%) and 2007 (61.1%) but still lower than in 2006
(71.7%). Although the percentage of moderately to severely defoliated conifers is still high, it
does not have a stronger impact on the overall percentage of trees of all species for the same
defoliation classes, because of the low representation of coniferous trees in the sample (242
coniferous trees vs. 1 749 broad-leaved trees in 2009).
Abies alba was still the most damaged tree species, the percentage of moderately to severely
defoliated trees recorded in 2009 was 72.2%, compared to 69.7% in 2008 and 67.9% in 2007.
The lowest value with 36.6% of moderately to severely defoliated trees was recorded in 1988,
whereas in 1993 the respective share was 70.8%. In the year 2001, it reached 84.5%, and after a
slight decrease in 2002 (81.2%), the trend of increasing defoliation continued with 83.3% of
moderately to severely defoliated trees in 2003, 86.5% in 2004 and the peak at 88.5 % in 2005.
The lowest percentage of moderately to severely defoliated or dead Quercus robur trees was
recorded in 1988 (8.1%), the highest percentage in 1994 (42.5%), and it has been fairly constant
later at around 25-30% until the year 2000. Afterwards it decreased to values below 20% (15.4%
in 2003, 18.5% in 2004). In 2005, a slight increase was recorded with 22.1% of moderately to
severely defoliated oak trees. In 2006, it was slightly lower at 20.5%, and in 2007 it was again
lower at 19.6%, returning to values above 20% in 2008 (22.2%) and in 2009 (22.8%).
Fagus sylvatica remained the least damaged tree species in Croatia. The maximum percentage
of moderately to severely defoliated beech trees was recorded in 2001 (12.5%), and in
subsequent years even lower values were recorded: 5.1% in 2003, 7.5% in 2004, 7.0% in 2005,
6.3% in 2006, 7.6% in 2007, 7.0% in 2008 and 7.8% in 2009.
Overall, the state of crown defoliation in Croatia remains fairly stable, although the condition of
some important and sensitive tree species slightly deteriorated.