The diploma thesis deals with the issue of chronic ash-trees dying. The analysis was performed in five forest stands at LHC Podhájska. It monitors the main symptoms of damage caused by chronic death vectors of ash-trees, including the fungus Chalara fraxinea, beetles of the genus Leperisinus, fungus of the genus Armillaria, wild animals and drought.Analyses showed that the stands are significantly damaged. Different type of damage dominated depending on the growth phase. Due to the fact that the proportion of ash in the Podhájska LS is 8%, it is vital to focus on rescuing this tree, because its position in these forest ecosystems is irreplaceable.The thesis summarizes the procedure of defence and protection against this disease and the procedure of growing forests in areas where this disease occurs.