THE FEATURES OF TREE MORTALITY IN PINE FORESTS DUE TO CHRONIC AIR EXPOSURE POLLUTION

The structure of tree mortality in the Cherkassy pine forest stands and their dynamics has not been investigated, as it requires longlasting permanent studies. The aim of our research was to investigate the dynamics of the current trees mortality for 20 years. Stationary ecological profile, which was founded in 1988 by suburban forest edge deep into Cherkassky forest allows us to track the change of descriptive quantitative indicators of forest stands over time. It is the largest natural array of Pinus sylvestris L. in foreststeppe of Right-Bank Ukraine, a key element of the national ecological network. Cherkassy Bor forests are affected by Cherkasy industrial agglomeration phytotoxic emissions (SO2, NOx, NH3, dust). Trees infestation has been defined by status categories, extent of plantations damage has been established with the average index of the stand state (Is). Trees that have fallen in 20 years were subject to accounting. The state of Ecological Profile stands became worse from poor to very weak for 20 years. It has average mortality level (15–21%).There is trees mortality for II–III Kraft grade, the main forest tent trees, which are the best and healthiest in forest ecosystem, at a distance of 10–16 km from Cherkasy industrial agglomeration. That indicates their air pollution damage. 18% of fresh dead wood at the distance of 10 km from industrial agglomeration were II Kraft class trees. The structure of fresh and old dead wood showed that II, III Kraft class trees withered away. Excessive human pressure on Cherkasky forest pine plantations resulted in their natural forms and structures simplification, violated the stability and resistance of forest ecosystems, causing pathological trees mortality. This is confirmed by the lack of correlation between stands state index in Cherkassy Bor and their age.