It is shown that key factors affecting negatively on trees nutrition status within urban territories (the cities of Irkutsk, Angarsk, Usolye-Sibirskoye, Shelekhov in the Eastern Siberia) are a high level of air pollution caused nutrient elements disbalance in trees and soils, and a heavy recreation loading resulting to deterioration of morphological and physical soil parameters. It is found that sulphur dioxide, as well as heavy metals, have the most negative effect on the trees nutrition status. ese pollutants affect by the direct foliar absorption and indirectly way through the polluted soils. Close connections have been revealed between the trees nutrition status disturbance and reduction of the parameters reflecting tree vital condition. It is concluded that trees nutrition status disturbance can be used as an adequate integrated indicator for detection the effect of negative factors (air pollution, recreation loads, insect attacks, fungal diseases) to an urban ecosystem.