Characteristics of the forest growing season in Poland on the basis of selected scenario of climate changes

The paper presents comparative characteristics of the length as well as start and end dates of the forest vegetation period (FVP) in the years 1981−2010 determined on the basis of the average daily air temperature and data generated for the conditions of two−fold higher CO2 concentration. To simulate meteorological data for that conditions, we applied the WGENK data generator, considering assumptions of GISS Model E scenario of climate change. The results showed that the average start date of FVP in Poland in the period of 1981−2010 was April 25th, while the average end date of FVP was October 10th. The average length of FVP for Poland equalled 165 days. It was discovered that, on average, the FVP start accelerated by 8 days per 30 years and the FVP end was slightly delayed by 3 days per 30 years. During the analyzed period, the FVP in Poland extended by 10 days on average. According to the applied scenario of the climate change, the trend indicates a possible increase in the FVP by 30 days when compared to the present state. The FVP may start 2−3 weeks earlier and finish 1−2 weeks later than presently. The generated data pointed at April 9th as the average date of the FVP start and October 24th as the date of its end