Effect of the forecast climate change on the sweet cherry tree water requirements in the Bydgoszcz region

The aim of the present research has been an attempt at estimating the water requirements of sweet cherry tree in 2016-2050 in the Bydgoszcz region drawing on the forecast temperature changes. The paper draws on the forecasting of mean monthly temperature for the Bydgoszcz region in 2011-2050 according to the climate change scenario for Poland SRES: A1B (Bąk, Łabędzki 2014). The water requirements of the sweet cherry tree have been determined based on the indispensable precipitation determined by Kemmer and Schulz. The water requirements were calculated for the period January through December and May through September for each year in the 35-year period (2016-2050). The reference period was made up by a 35-year period immediately preceding it (1981-2015). In 2016-2050 in the Bydgoszcz region, in the light of the forecast temperature change scenarios, one can expect an increase in the water requirements of the sweet cherry tree. Determined with the Kemmer and Schulz method, the required annual (January-December) optimal total precipitation will increase for the sweet cherry tree from 532 mm to 746 mm (by 214 mm, which accounts for 40%). The optimal precipitation trend equations show that in the reference period (1981-2015), calculated with the Kemmer and Schulz number, the optimal annual precipitation was increasing in the sweet cherry tree in each pentad by 2.4-3.0 mm. In the forecast period (2016-2050) the water requirements will increase, however, in each pentad within a much greater range, from 13.0 to 14.5 mm. In the summer period (May through September) determined by Kemmer and Schulz, the total precipitation optimal for the sweet cherry tree, expressing the water requirements, in 2016-2050 will increase by 107 mm.