Effect of the forecast climate change on the grapevine water requirements in the Bydgoszcz region

The present research has aimed at estimating the water requirements of grapevine in 2016-2050 in the Bydgoszcz region based on the anticipated 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 grapevine 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 the 2016-2050 period in the Bydgoszcz region, in the light of the anticipated temperature change scenarios, one can expect increased grapevine water requirements. Determined with the Kemmer and Schulz method, the required optimal annual (January-December) precipitation will increase for the grapevine from 440 mm to 576 mm (by 136 mm, namely by 31 %). The optimal precipitation trend equations demonstrate that in the reference period (1981-2015), calculated with the Kemmer and Schulz, the optimal annual precipitation was increasing in grapevine in each pentad by 2.2-2.6 mm. In the forecast period (2016-2050) the water requirements will increase, however, in each pentad in a much greater range (8.0-8.9 mm). In the summer period (May-September) determined by Kemmer and Schulz, the total precipitation optimal for the grapevine, expressing the water requirements, in 2016-2050 will increase by 68 mm.