For the first time, method of estimating system stability for investigation of the forestry problems, developed in Germany, was used. Threat indicators (mass outbreaks of pests and diseases) caused by climate change were calculated, and the value of forest ecosystem sustainability in Russian Federation is determined. It was found that the main forest area is sufficiently resistant to investigated factors. Data analysis on sanitary situation of forest vegetation zones of the Russian Federation indicated that, in some regions, the threat of loss because of forest diseases and pests in the forest is minimal one.