Frequency of dangerous hydrometeorological phenomena in Russian forest biomes

Dangerous hydrometeorological phenomena periodically cause damage to natural systems in the form of irreversible transformation of ecosystems and mass death of organisms. In forest biomes, the following phenomena break trees: strong wind, tornado, heavy snow, blizzard, heavy icy-frost deposition. The irreversible transformation of ecosystems is caused by mudslides, landslides, avalanches, and coastal erosion. Their volumes sometimes exceed 1 million cubic meters. The mass deaths of animals and plants are caused by: heavy rain (washing away vegetation and soil), large hail, dust (or sand) storms, extreme frost, abnormally cold weather, extreme heat, abnormally hot weather, hot dry winds, drought, high snow cover (death of ungulates), ice crust (deaths of ungulates and small mammals), flooding (of various origins). For each of these phenomena we identified two threshold levels of intensity: critical (when the phenomenon begins to cause damage, for example, healthy trees break) and catastrophic (when the forest dies on an area of several hectares). According to observations at 153 meteorological stations, 8 phenomena associated with strong winds, extremely high and low temperatures, flooding, exceed the first threshold in forest biomes almost annually. Also, frequent hazards are: heavy rain (coastal and mountainous biomes of the Caucasus and the Far East) and/or heavy snow (northern biomes, Pacific coast, Altai and Ural Mountains). The rate of costal erosion reaches 5 m per year. Most of the dangerous phenomena reached the catastrophic threshold of intensity less than once in 10 years or were not recorded. Only 5 of them were manifested in the most biomes and can occur annually in at least in one of them: high snow cover, icy-frost deposits, severe frost, tornadoes and floods. In the forest biomes of Siberia, severe frost (- 50 °C) is observed annually or every 5 years, whereas in the Moscow region it was noted once in 1940.