Crown condition

FutMon logoINBO coordinates a yearly assessment of the forest health status in the Flemish region of Belgium, following the ICP Forests manual. This forest condition survey aims at a general description of the forest condition in Flanders and more specific for some important tree species. The changes in crown condition are considered and, if possible, explained.

The European crown condition survey (Level I) is developed by means of a systematic grid of 16 by 16 km. In total this sample exists from more than 130,000 trees. Nine of the Flemish plots are part of this international network.

The 72 plots of the Flemish survey are situated on a 4x4 km grid. In each plot 24 trees have been incorporated in the survey. The most common tree species in the inventory are European oak (Quercus robur), Scots pine (Pinus sylvestris), Common beech (Fagus sylvatica), American red oak (Quercus rubra), Corsican black pine (Pinus nigra subsp. laricio) and poplar (Populus sp.). During the summer months the defoliation of these sample trees is assessed and damage symptoms are described. The observers assess the defoliation in steps of 5%. Afterwards, the trees are classified in damage classes. Trees with more than 25% defoliation are damaged. A distinction is made between slightly and heavily damaged trees. A healthy tree is a tree with a maximum of 10% defoliation.

Attention is paid to a large set of possible damage symptoms on leaves, branches, stem and collar. The extent of the damage is assessed and if possible, the cause of the symptom is reported. Abnormal discolouration means that more than 10% of the crown shows discolouration. Other possible symptoms are partially or totally devoured leaves, dead branches and dead twigs, wounds, deformations, signs of insects or fungi,…

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