First results of assessment of the state of forests in permanent areas
1992
Frey, T. | Frey, J. | Lohmus, K. | Kask, P. (Tartu Univ., Tartu (Estonia). Ecosystems Laboratory)
In accordance with internationally approved methods in 1987-1988 the Ecosystems Laboratory of Tartu University set up ten control areas for permanent observation of the condition of the forests there. The control areas were created in stands of coniferous trees. In the stands under investigation a decrease was registered in the increment of the basal diameter over recent years, caused by acid rains. More than every third of the trees checked was bearing some signs of damage. The damage of crowns consisted in thinning the spreading outward from inside, which refers to a prolonged chronic process of impairment. The trees with impaired crowns had also damaged roots: the number of their active tips had decreased, their bark was ulcered, or there were deformations
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