The diploma deals with the condition of oak forests in the forestry unit Ravensko. The geographic distribution and endangerment of oaks (Quercus spp.) in Slovenia were stated. Our special interest was in the English oak (Quercus rubor L.). Researches of the extensive oak decay have already been made. Basedon the results of those researches, decision was taken to determine the factors that affect the vitality of oak. In the diploma the biotic factors were presented. The experimental part of diploma contains analysis of collected oak acorns and present damage by (Curculio glandium Marsham) and (Andricus queruscalicis Burgdorf). Tree damage in the vegetation season of the year 2006, 2007 and 2008 at the location of Hrašica and Ivanjci was evaluated. In the description of the forest health, Manual for the Assessment of Damage Sources (work version) was used. The assessment of tree species vitality is possible only in the accordance with the instructions of the Manual for the continual research on the permanent research plots and in longer periods. The results of our research indicated the increased presence of defoliators and the damages caused by oak powdery mildew (Erysiphe alphitoides Griffon & Maubl.) in the year 2007.
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