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• Oak mortality should be seen as a combination of long- and short-term stresses, wherefore an identification of one specific factor causing the actual death of the oaks in this study is impossible.
  
   
• In order to fully understand the causes of oak mortality there is an equal need of studying present as well as past factors influencing the oaks’ vigour, since the history of a tree is essential for its present chances of survival.
  
   
• Although this study presented a rather modest influence of the impact of environmental variables on oak mortality, site specific properties should not be considered unessential when analysing the causes of oak mortality.