| ABSTRACT | Agriculture sector is very sensitive to climate variability, especially during growing season. However, climate conditions during dormancy are also very important for some agricultural crops. Since the climate variabilty is usually not uniform throughout the year, we evaluated recent temperature trends in Serbia for the growing season and dormancy, separately. The analysis was based on temperature observations from 26 uniformly distributed meteorological stations. The observation period (1961–2010) was split into two parts (1961−1980 and 1981−2010) according to the results of the sequential Mann–Kendall test for detecting change points in time series. The temperature metrics included: maximum temperature (Tx), minimum temperature (Tn), mean temperature, warm days (number of days when Tx> 90th percentile), warm nights (number of days when Tn > 90th percentile), cool days (number of days when Tx < 10th percentile), cool nights (number of days when Tn < 10th percentile) the hottest day (the highest Tx), the hottest night (the highest Tn), the coldest day (the lowest Tx) and the coldest night (the lowest Tn). Temporal trends were evaluated by a least-squares linear regression method for each station and for the entire Serbian territory using the average series. The statistical significance of the trends was detected using a t-test.
Results revealed uneven changes of temperature within the observational period. Dormant temperature changes were uniform during the whole period (1961–2010), while pattern of growing season temperature changes was rather complex. In the sub-period 1961−1980, all examined temperature indices exhibited a cooling tendency during the growing season, with growing season mean temperature decreasing at a rate of −0.73 °C decade on average for all stations. A larger decreasing trend was detected in growing season Tx (a nationally averaged rate −1.10 °C per decade) and indices related to Tx than in growing season Tn (a nationally averaged rate −0.37 °C per decade) and indices related to Tn. In the same sub-period, temperature indices displayed a warming tendency during dormancy, with growing season mean temperature, Tx and Tn increasing at same rate of 0.49 °C per decade on average for all stations. In the sub-period 1981−2010, warming tendency of all examined indices was detected in the growing season, as well as in dormant period. Mean temperature increased at same rate in both periods (0.52 °C per decade on average for all stations). Similarly, growing season and dormant Tx and Tn and related indices showed a warming tendency with similar magnitudes of the trends. A nationally averaged rate of 0.55 and 0.49 °C per decade was detected for growing season Tx and Tn, respectively, while dormant Tx and Tn increased at almost exactly the same rate, 0.56 and 0.49 °C per decade, respectively. |