|
|
Forest damage (2.4)
|
Figure 2.4a. Occurrence of damaging agents reducing stand quality in timber production, 2008.
Source: Finnish Forest Research Institute, National Forest Inventory |
 |
Figure 2.4b. Forest fires 1970–2010.
Source: Ministry of the Interior, Department for Rescue Services, Pronto database |
Forest damage can be caused by various abiotic10 and biotic11
agents. Damage caused by diseases or other damaging agents
to individual trees is normal in forests, but if biotic agents succeed
in spreading over large areas, forest damage is considered
to have occurred. The prevalence of damaging agents and
the resultant damages vary depending on pest populations and
weather conditions.
No extensive forest damage has occurred in Finland in the last
few decades. This is partly due to the strict legislation on insectand fungi damage prevention, restricting the storage of timber
in the summer. Between 2004 and 2008, damages requiring immediate
regeneration occurred over a total of 38,000 hectares.
Lesser damages occurred in larger areas. Damages necessitating
regeneration were caused above all by snow, wind and moose,
as well as Scleroderris canker and resintop disease. Most of the
causal agents remain unidentified, however.
Continuous damage is caused in southern and central Finland
by Annosus root-rot, which primarily attacks conifers. The increased
moose population causes damage to seedling stands
of pine and birch in particular, but also of spruce. There are also
local epidemics of Scleroderris canker, pine sawfly, autumnal
moth and voles. Wind and snow can also cause significant
damages locally.
In summer 2010, an exceptionally long spell of warm weather
in southern Finland led to violent storms proceeding along two
or three narrow corridors, damaging and felling trees with a volume
of about 8 million cubic metres. This was the most extensive
storm damage seen in Finland in decades. In December 2011 several million cubic metres of wood were thrown by high winds. In 2001, the storms
named Pyry and Janika felled 7.3 million cubic metres of wood
in South Ostrobothnia and Häme. Hundreds of small forest fires
occur in Finland every summer, but thanks to efficient monitoring,
a dense network of forest roads and a smoothly functioning
fire-fighting system, fire damage remains slight.
 |
 |
| Root-rot (Heterobasidion parviporum) is the most destructive fungus of conifers in southern Finland. In worse cases the whole forest stand has to be harvested and the tree species change is necessary. |
Moose (Alces alces) is an important game species in Finland, but it also causes serious damages to seedling stands. Moose populations are therefore regulated systematically. |
Links
10 Abiotic agents are wind, snow, sub-zero temperatures, other climate and
weather conditions, forest fires, soil-related factors, logging, atmospheric pollutants,
and other human activities.
11 Biotic agents are fungi, insects and vertebrates
|
