Metode de evaluare a riscului de apariţie a vătămărilor de zăpadă în pădurile din România [Methods for the evaluation of risk to snowdamages in Romanian forests]

Statistical information prove that in the last 50 years the damages caused by snow in forests (especially in the coniferous forests) significantly increased. The research aims are to propose an holistic analisy of the snow damages in forests and for the management of the risk. A better knowledge of the risk can reduce of the impact of catastrophic damages as much is possible and restore the damaged forests in such way so that further catastrophes may be limited in their extent and effects. The main causes of the occurrence of snowdamages are: (a) the structural modifications of forest landscape under human activities, through extension of the artificial coniferous plantations; (b) climatic changes with major effects, represented by the catastrophic rainfalls in short time (1-3 days) in the same region. When these are liquid, the catastrophic floodare are registered and when the precipitation are in snow-form, snow-damages in hilly forests or avalanches in high mountains are registered too. More than 10 catastrophic snow-damages have been reported in the last 20 years in Europe. In some regions, snow and wind damages represent more than 40-80 % of sustained cut in 10 years, with severe effects on the forest management and wood market. In comparison with the wind damages, snow damages are more dangerous, because appear, generally, in young stands, and the management of damaged stands is more difficult and risky. In forests, snow damages are examined in relation with the geographical and meteorological conditions: (a) identification of the natural parameters in different region of Romania for the evaluation of natural risk to snow damages; (b) meteorological and climatological factors which determine snow damages in forests (determinant factors); evaluation of the risk on the basis of determinant factors - probabilistic model; (c) identification of the predisposant and incitant factors in snow damaged forests and quantification of their influence; (d) development of the methods and mapping criteria for the prognosis of risk to snow damages; (e) production of the methods for snow risk analisys and the specific management of stands; (f) rationalization of the financial and human efforts with an increase of the forest stability. The results are the based on the autor's experience in the research and evaluation of four catastrophic snow damages in Romania (1977, 1979, 1993, 1996). Some proposals for the evaluation of stands stability to snow and for the snow risk mapping of the Romanian territory have been developed in recent years.