## 1 Introduction  
The increase in the range and population density of large wild ungulate animals has been documented over the last century in many European countries [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] and other parts of the world [11, 12, 13]. The increased population density often leads to losses in crops [14] and tree stands [15, 16]. The presence of red deer (_Cerus elaphus_ L.) in commercially forested areas can cause considerable conflict between forestry interests and wildlife management because red deer can severely damage forest stands by browsing and bark stripping [17, 18, 19, 20]. Bark stripping is primarily determined by ruminant dietary physiology. Ruminant energy requirements change depending on the phenological season, atmospheric conditions and the age and physiological condition of cervids [21, 22, 23]. In a summer month, deer require between 16 kg and 17 kg of green proverd in their diet [24], with the animals feeding on 256 plant species [21]. This diversity results from the fact that the animal intuitively consumes plants that supplement its demand on proteins, carbohydrates, fats and micro- and macro-elements in a given period [25]. The digested leaves, shoots and young unlignified bark provide natural food for cervids. They have a high nutritive value and complement coarse fibre components, which explains their consumption by deer, especially in periods of poor access to food [22, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34]. Studies containing seasonal data show that the bark constitutes more than 10% of food consumption during the winter period (between December and March) [32]. [PERSON] et al. [35] calculated that the winter demand of deer on the bark ranges from 55 kg to 77 kg of dry mass. Analyses of the credit diet also reveal a correlation between an elevated share of young grasses and herbs in the deer diet and the simultaneously increasing number of tree stripping instances [36]. Unfortunately, the specific dietary requirements of cervids are not taken into account in winter food supplementation, which may lead to damage aggravation. The animals, provided with additional food by hunters, predominantly with juicy and strengthening fodder, balance their food intake by consuming larger amounts of fibre contained in the bark. This allows them to maintain a balanced pH value [17], large active surface and access for the enzymes to the food content in the rumen [23]. The supply of more balanced food in a comprehensive feeding programme could decrease the extent of bark stripping [37]. The deer also consume bark because of its antiparasitic effects [17; 32]. The stress stemming from the anxiety felt by the animals during rumination causes disadvantageous physiological changes to appear, leading to rumen acidosis. The animals often react by consuming fibre-rich food in such situations. This was confirmed in Belgian studies, which showed intensified tree stripping by deer previously startled when ruminating [22]. The factors that contribute to increased stripping include the tree stand composition and structure and high density of the deer population [17]. There are 282,000 deer (_Cervus elaphus_ L.) in Poland's forests, which cover about 8 million hectares [38]. One of the most severe instances of damage caused by deer in a forest is bark stripping. Coniferous trees are more affected by bark stripping than broad-leaved trees [15]. The consequences of bark stripping are closely linked to the tree's specific sensitivity to pathogens once the wood has been deprived of its protective bark [33]. Debarking lesions are difficult to heal on trees, and the process can take up to 30 years [39]. The healing over of pine bark damage is not completed with calluses but through sealing. The edges of the wound gradually converge due to annual growth, eventually covering it [39]. Damage to the bark is not always completely sealed. The axis trunk at the stripping damage height remains asymmetric, which causes a shift in the tree axis, with a visible ovality of the trunk.