*3.1. Differences in Meteorological Conditions at the Experimental Sites*

During May–September from 2014 to 2016, the year 2015 was exceptionally dry compared to 2014 and 2016 (Table 4). Additionally, 2015 was characterized by significantly higher mean VPD values (*p* < 0.001; Table 5) during the main growing season as compared to the same period in 2014 and 2016 across both sites. Hence, the mean VPD and SVWC values were the best meteorological indicators of drought, while Tair was comparable for years 2015 and 2016. Consequently, the high atmospheric evaporative demand (high VPD values) and low soil moisture (low SVWC values) recorded in 2015 across both sites during the study period further indicated the dryness stress experienced in the main growing season of 2015.

**Table 5.** Mean values of vapour pressure deficit (VPD), air temperature (Tair) and soil volumetric water content (SVWC) during the main growing season in years for both spruce forest stands.


There were observed statistically significant differences (*p* < 0.05; Mann–Whitney– Wilcoxon ranksum test) in the VPD and SVWC values between the normal and drought regimes across both sites (Figure 1). In addition, VPD was higher and SVWC lower at CZ-RAJ than at CZ-BK1, especially during the drought-affected year (DY).
