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This paper uses GIS to describe and evaluate forest fire risk considering the most important factors affecting fire behavior at fine scales. The study was implemented in Yeşilova Forestry Enterprise in the Mediterranean city of Kahramanmaraş, Turkey. To determine an overall fire risk index for the study area, fire risk rating (extreme, high, moderate, or low) was assigned to decision variables (i.e. species composition, stand development stage, stand crown closure, slope, insolation, settlements, and roads) according to their risk potentials. Additionally, the visibility analysis of fire towers was carried out for monitoring of forests in the case study area. Finally, visibility analysis and a forest fire risk map were evaluated together for determining the efficiency of fire towers. Results indicated that more than half of the total forested area (65.7%) was classified as low category in the fire risk map. According to visibility analysis, the existing fire tower was able to monitor only 37% of forest areas; therefore, it was essential to consider new fire towers for monitoring the overall study area. After locating a potential new fire tower in the study area, it was found that about 71.8% of the area was with the visible zones of two fire towers.
Natural forest fires are considered as a part of natural ecosystem processes. Short-term effects of prescribed fire on densities and taxonomic diversity of soil Acari were studied in fresh pine mixed forest (“Biala” forest ) in the Mazovia region, Central-Eastern Poland. Three plots (size 1 m²) of similar soil type and vegetation were selected for prescribed burning. Soil samples of an area of 10 cm² and the depth of 5 cm were collected in June 2005 – one day after the burning, 60 days after the burning and 90 days after the burning. Samples were collected from within the border of the burned plots, from the border itself, as well as from the surroundings. Due to the burning, the density of Acari communities decreased from 11.5 × 10³ ind. m⁻² recorded in the surroundings to 3.2 × 10³ ind. m⁻² recorded in the burned plots. Values recorded within the burned plots after the fire differed significantly from those recorded on the border (P = 0.05) and in the surroundings (P = 0.0001). After 60 days, an increase in Acari abundance was observed in the burned plots (P = 0.02), becoming similar to that noted for the border of the plot and for the surroundings. After 90 days, there were no significant differences between the burned parts of the plots, their borders and the surroundings; however, generally decreased densities were observed, possibly due to the seasonal reason. The observed changes suggest the restoration of Acari community after disturbance.
Our study analyzed the fire (pyric) environment (vegetation or fuels, meteorology, topography, suppression time) of the large forest fires (greater than 1,000 ha) that occurred in Greece during 1990-2003. Statistical analysis of 84 large fires (representing 0.37% of the total number of fires) revealed that they usually spread under moderately to low relative humidity (21-40%) in the presence of strong to moderate northern winds. Approximately one-fourth of all large fires occur during heat waves (i.e. air temperature higher than 30℃ and air relative humidity 21-40%). Large fires occur as both surface and crown fires and usually spread in dense vegetation with a continuous duff layer. Successful containment requires a combination of both ground and aerial fire suppression forces. Although large forest fires usually have short initial attack time (less than 30 minutes), the suppression time is variable. The main differences between the large fires and all the others lie in the prevailing wind speed (strong for large fires, moderate for smaller fires) and the mode of propagation (mixed surface and crown spread for large fires, only surface spread for smaller fires). However, no unique characteristics of large fires were found that would distinguish them from smaller fires. This supports the hypothesis that any fire may become large under certain circumstances. The results of this study could be useful in forest fire danger rating and presuppression alertness in the context of judicial fire prevention and suppression planning.
Our paper presents results of investigations aimed at determining correlations between the content of polycyclic aromatic hydrocarbons (PAHs) and the enzymatic activity of a forest soil on an extensive area of forest damaged by a large fire 12 years ago. The investigations comprised experimental plots in the cultivations of Scots pine (Pinus sylvestris L.) and grey alder (Alnus incana L.) MOENCH on three sample surfaces on which different methods of soil preparation were applied. The statistical analysis of the obtained results clearly showed the inhibiting influence of the PAH content on the activity of dehydrogenases, acid phosphatase, alkaline phosphatase and protease, which indicated that the examined soils were loaded with PAHs to such a degree that it was dangerous to living organisms. A highly significant positive correlation was found between urease activity and PAH content.
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