Quantifying the Drying Phenomenon of Oaks by Highlighting the Defoliation of Stands

Ioan Tăut, Vasile Șimonca, Mircea Moldovan, Tatiana Blaga

Abstract


The stands decline can be due to structural or functional disturbances, in which several categories of disruptive or harmful factors compete and interact in different ways and directions, but whose outcome is weakening the trees vigor, culminating with their death. The harmful agents may be abiotic or biotic. The biotic agents include bacteria, fungi and insects that are not able to invade in normal circumstances, and cause significant harm to healthy trees, but can be very destructive when attack devitalized trees. Leaf defoliation or loss due to biotic or abiotic factors is the most frequent and easier symptom to be quantified at the tree level and stand. Due to this phenomenon, trees slow their growth, suffer disturbances of nutritional regime, stands being subject to stress phenomenon that will culminate with the decline of those stands. In terms of defoliation, stands recorded values ranging between 4 to 38%. Weak or moderate defoliation were recorded only in oak subarea, where they ranged between 15-38%. Most affected were stands from the Forestry District Satu Mare, defoliation being the result of Lymantria disapar pest attack (30-35%).


Keywords


Forestry District, attack, Lymantria dispar, analyze of the simple variance.

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