(07/10/2010) - Summer 2010 was unusually dry and warm in Southern half of Finland. The effects on vegetation and trees will become visible in thenear future writes the Finish Forest Research Centre. Drought and unusually warm weather cause stress in trees and lowers their tolerance against pests and diseases. In the next few years the consequences may be seen as higher mortality rates of trees.
The drought risk is higher on spruce (Picea abies) because of its shallow rooting system. The risk exists also on pine (Pinus  sylvestris), which favours already dry and infertile sites .The  lowered tolerance of trees makes them more vulnerable to insect  species such as bark beetles. Warmer conditions in Finland might  able some bark beetle species to produce two generations  instead of just one. In addition to warmth and drought Finish  forests also experienced serious storms which fell down millions  cubic meters of trees. If not harvested in time the large dead
wood material may work as a breeding ground for pests.

Of course some signs of the warm summer were also more or less immediate in the Southern and central parts of Finland.
Leaves of park trees were hanging down and the berry yield in forests was really low. Many shrubs also got their autumn colour earlier than usual.

According the statistics dry summers are fairly common in South- and South-western Finland. Still the summer 2010 can be considered as unusually as the temperature rose to 35 C. Nonetheless the biggest growth limiting factors for tree growth in Finland are short growing season and the lack of nitrogen.