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ŠUMARSKI LIST 9-10/2023 str. 71     <-- 71 -->        PDF

The evapotranspiration factor and the monthly moisture index are equal to “0” for every average monthly temperature ≤0 oC. The monthly moisture index is limited to max. a value of 100 (all values > of 100 are taken as a value of 100), (Chandler et al.,1983).
The length of the average fire season was obtained by simply counting months with negative wetness indices. Positive monthly moisture index indicate fire-free seasons. Period one to four months with a negative monthly moisture index is a short fire season, and five to 12 months is a long fire season (Chandler et al.,1983).
The burning index is determined by the formula
                                                                                (3)
where:
B – Burning index
I – Intensity component
S – Spread component
and
                I = (110 – 1,373 H) – (20,4 – 0,054 T)               (4)
where:
H – Humidity Index
T – Monthly mean maximum temperature (°C)
and
                S = 124 ˙ 10–0,0142H (5)
where:
H = 100 ˙ (100,0308D / 100,0308T)
D – Monthly mean dew point temperature (°C).
The burning index is correlated with the fire behavior, which is determined based on the data from table 1.
For this research, statistical data from the Department for Emergency Situations (MUP of the Republic of Serbia) on the registered number of forest fires in the area of northeastern Serbia for the period from 2009 to 2022 were used. The Pearson correlation coefficient (r) was used to examine the possible relationship between the time series of the number of forest fires and the burning index.
RESULTS
REZULTATI
Climate conditions – Klimatski uvjeti
In the area of northeastern Serbia, the average annual air temperature ranges from 6.4 oC at Crni Vrh to 11.1 oC in Negotin (RHSS, 2023). Significantly lower air temperature values in the area of Crni Vrh are conditioned by the higher altitude of this place where the meteorological station is located (1027 m asl.). In relation to the multi-year average of mean annual air temperatures, Table 2 shows that at all meteorological stations there was an increase in air temperature in all years during the period 2009-2022. The deviation of the average annual air temperature compared to the reference period was the most pronounced in 2019.
In the area of northeastern Serbia, the hottest month is July, with an average daily temperature of 16 °C at Crni Vrh to 22.1 °C in Negotin. The coldest month is January with an average daily temperature of -4.2 °C at Crni Vrh to -1.4 °C in Zaječar (RHSS, 2023). In July 2012, the mean monthly air temperatures in Negotin were 5.1 oC higher than the multi-year average (RHSS, 2023). Tošić et al. (2014) state that 2012 was one of the warmest years in Serbia. For the period 2009-2022. every month of the vegetation period in the area of Negotin had higher air temperature values than the multi-year average.
In the area of northeastern Serbia, the multi-year average amount of precipitation is from 610.5 mm in Zaječar to 810.1 mm in the area of Crni Vrh (RHSS, 2023) (table 3).
For the period 2009-2022, in the area of northeastern Serbia, the least amount of precipitation was measured in 2011,