Reaction of shrubby willow biomass harvest on hunting damages at diverse fertilization with nitrogen

The aim of this study was to evaluate the reaction of 10 willow varieties to damage inflicted by hunting deer (Cervus elaphus L.) and European roe deer (Capreolus capreolus L.) at different fertilization with nitrogen (0, 60, 120 and 180 kg ha-1 N) in the years 2008-2011 in the vicinity of Koszalin. Such damages as grazing of tops of shoots, debarking and fracture of shoots and total damage were evaluated at the end of the willow vegetation period. Yield of fresh mass of shoots was determined in November 2010 (third year of cultivation) and 2011 (fourth year of cultivation). Regression equations for the yield of shoots at different damage hunting were created. Level of hunting damage was most strongly influenced by age of cultivation (21.7%), variety of willow (21.3%) and the interaction between of those factors (16.9%) and less – nitrogen (1.7%) and interaction between varieties and doses of nitrogen (1.1%). In the first and second year of regrowth of willow, in case of thin stems, grazing their tops dominated, and in the third and fourth year of cultivation, in case of thicker stems, their debarking and breaking of their shoots intensified. It was shown that for 1% of total loss, yield of fresh weight decreased from 0.251 t ha-1 for 1054 variety to 0.973 t / ha t ha-1 for Ekotur variety, and in average of 10 varieties – decreased by 0.416 t ha-1 . The authors would like to thank Lillohus AB company, 291 61 Kristianstad, Sweden for donation of Oloff, Jorr and Tordis varieties for test and to Mr. Przemysław Dobrzaniecki from Agrobränsle AB in Poznań for participation in this donation