Report - ICP Forests

104 4. National Survey Reports in 2009
After two years of severe aphid infestations (Elatobium abietinum) Picea sitchensis recovered in
2009 (13% average defoliation), but this is also due to harvesting of affected stands. Average
defoliation score of Fagus sylvatica increased slightly in 2009 (9%), but Quercus (robur and
petraea) stayed at the same level (14%). Picea abies showed very good health with an average
defoliation of 6%, and for other trees species the defoliation scores were generally low.
Based on both NFI plots and Level I & II plots, the results of the crown condition survey in
2009 showed that 74% of all coniferous trees and 62% of all deciduous trees were undamaged.
19% of all conifers and 27% of all deciduous trees showed warning signs of damage. The mean
defoliation of all conifers was 8% in 2009, and the share of damaged trees was 7%. Mean
defoliation of all broadleaves was 14%, and 11% were damaged.
4.9 Estonia
Forest condition in Estonia has been systematically monitored since 1988. In 2009, 2 202 trees
were assessed on 92 permanent Level I sample plots from July to October. The survey covered
602 spruces (Picea abies), 1483 pines (Pinus sylvestris), 92 birches (Betula pendula), 12 aspens
(Populus tremula), and 13 other broadleaves.
Scots pine (Pinus sylvestris) has traditionally been the most defoliated tree species in Estonia. In
general, defoliation of pines in NW and NE of Estonia is higher than in SW and SE regions.
Essential improvement in crown condition of Scots pine was observed in the period 1991–2000.
Then a certain decline was registered up to 2003 and since 2004 defoliation has remained on the
same level. In 2008-2009 37% of Scots pines (Pinus sylvestris) were not defoliated (defoliation
class 0). In general, some worsening of crown condition for Scots pine (Pinus sylvestris) was
noted in 2008, mainly because of the increase in the number of moderately and severely
defoliated trees, but in 2009 a certain improvement was observed again.
The increase in defoliation of Norway spruce (Picea abies) which started in 1996 stopped in
2003, and remained on the same level up to 2005. In 2006 some worsening in crown condition
occurred. In 2007-2009 the level of Norway spruces which were not defoliated (defoliation class
0) remained almost at the same level 54-58%.
Numerous factors determine the condition of forests. Climatic factors, disease and insect
damage as well as other natural factors have an impact on tree vitality. 3% of the trees assessed
had some kind of insect damage, and 44% identifiable damage symptoms of disease. Needle
cast (308 trees damaged) and shoot blight (560 trees damaged) were the most significant reasons
of biotic damage of trees, whereby the number of pines, affected by shoot blight was higher than
in 2008.
However, the condition of deciduous species was estimated to be better than that of the conifers.
In 2009, 61% of birches were not defoliated (defoliation class 0). The highest defoliation
amongst deciduous trees was observed for aspens (Populus tremula) and ashes (Fraxinus
excelsior).