The economic aspect of establishing fire breaks along public roads and reducing the losses caused by forest fires

The basis for the analysis was information on forest fires that was given in the forest district reports in the State Forest Information System, which was transferred to the National Forest Fire Information System (NFF-IS). In developing the analysis, the occurrence of fires on public roads was compared to all forest fires that occurred from 2017 to 2021. To select fires that occurred on public roads, 30-m-wide forest fragments were defined at the boundaries of forest complexes corresponding to the width of type A strips and the width of the cleared forest of lying flammable materials. The next step was to select forest fragments located along paved roads. At this stage of the work, data on the location of roads collected in the Database of Topographic Objects (DTO) and available on the Geoportal website (https://www.geoportal.gov.pl/pl/dane/baza-danych-obiektow-topograficznech-bdot10k/) were used.

Of all the roads contained in the DTO database, those with a natural ground surface were removed. In the next step, 50-m-wide buffers were created along the roads. The larger width compared to the A strip resulted from the fact that the DTO data does not contain detailed information about the width of the road and the road strip. Then, the common part of the generated buffers and 30-m forest fragments at the edge of forest complexes were selected, assuming that these are places where A-type strips or land clearings should be made. The final step was to determine the origin of the fires that were located on the A-type strips using the coordinates. All analyses were conducted by assessing the proportion of fires on public roads according to each criterion compared to the proportion of all wildfires. The criteria to be used to characterise fires on public roads were duration of fire response, number of rescue and firefighting units, area of fire, type of fire, cause, method of detection, age of stand, type of ground cover and type of forest habitat. In addition, air temperature, relative humidity and litter moisture were taken into account as the criteria that influence the degree of forest fire risk.

The analysis of losses caused by fires on public roads was carried out based on data collected in NFFIS from 2017 to 2023. In the analysis, fires on military training grounds and fires for which duplicate reports were prepared by forest districts, for example, because the same fire affected several departments, were not considered. To ensure the accuracy of the data, fires that occurred in the same forest district and at the same time and involved the same number of fire brigades and the same number of waters drops from an aircraft were also excluded.

The next step was to determine whether a particular fire occurred on or off a fire break. This part of the work was carried out in the manner described in the methodology for analysing the occurrence of fires on public roads. For a more comprehensive assessment of the economic impact of fires, the size of fires and the losses they caused were compared for fires that occurred on roads and fires that occurred in other forests. This analysis included a comparison of the average values of the above parameters and an assessment of the significance of differences in the values of individual parameters depending on the location of the fire. The Mann–Whitney test was used to assess the significance of the differences.

The analysis was based on data from the Directorate General of State Forests on the costs of establishing new and maintaining existing fire lanes and clearing the area in the years 2018–2022. The analysis also took into account differentiation of the above-mentioned costs depending on the forest fire risk category of the forest districts in relation to their forest area.

In the period analysed, there were 11,106 fires in the State Forests covering an area of 3,780.44 ha, of which 768 fires with a total area of 55.46 ha occurred along public roads. The average area of a fire in all forests was 0.34 ha, while along roads it was 0.07 ha, which is about five times less. The proportion of fires along roads in the total number of fires was 6.92%, and the proportion of burnt area was 1.47%.

To determine the characteristics of fires along public roads, their proportion compared to fires in forests was analysed based on 12 selected criteria that correspond to the methodological assumptions. Below are examples of the main results of the analyses.

Regarding the type of fires, ground cover fires dominated (almost 90%), regardless of where they occurred (Fig. 1). There were slightly more fires in total stands in other forest areas than along public roads. The trend was reversed for individual tree fires, as these fires were more frequently recorded along roads. There were no underground fires along roads. The lower number of fires in the stands and the lack of surface fires along public roads are due to the longer duration of the fire required for the fire in the ground cover to turn into a surface or subsurface fire.

Figure 1.

Occurrence of forest fires along public roads against the background of all fires by the type of fire (types of fires: TREES – total stand of trees, SINGLE – single tree, SUBSUR – subsurface, SOIL COVER – soil cover)

A certain correlation was recognisable in the investigated criterion of the type of ground cover (Fig. 2). In stands with a well-developed ground cover (sodded cover – SOD and heavily infested with weeds – VWEED), the proportion of fires near public roads was higher compared to all forests. In stands where the ground cover layer consisted only of mosses and blueberries (moss cover – MOSS and moss blueberry cover – MOOSB), the proportion of fires near public roads was lower.

Figure 2.

The occurrence of forest fires near public roads against the background of all fires by the type of soil cover (soil cover type: MOSS – moss, MOSSB – moss – blueberry, WIT – without litter, HSOD – heavily sodded, VWEED – heavily infested with weeds, LITT – litter, SOD – sodded, HERB – herbaceous)

The next analysis concerned the occurrence of fires in relation to the size of the burnt area (Fig. 3). For fires with an area smaller than 0.2 ha, the proportion of those that occurred on public roads was greater than the proportion of all forest fires. The situation was reversed for fires with an area of more than 0.2 ha: they were significantly more numerous in all forests than on public roads.

Figure 3.

Occurrence of forest fires near public roads against the background of all fires after the fire area

When analysing the methods of fire detection (Fig. 4), a clear differentiation can be seen, which is understandable. On public roads, significantly more fires (approx. 75%) are detected by bystanders (other persons [OTH]), which can be attributed to greater penetration of these areas. A greater proportion of fires detected by obser-vation points (OPOI) and aerial patrols (APAT) were found in the depths of forest complexes.

Figure 4.

Occurrence of forest fires near public roads against the background of all fires by the detection method (detection method: OTH – other persons, GPAT – ground patrols, OPOI – observation points, APAT – aerial patrols)

A significantly higher proportion of fires on public roads that were extinguished in a very short time (up to 45 min) was clearly visible. They accounted for almost half of the events analysed. For fires that took between 45 min and 1 h to extinguish, the proportion of fires on public roads was still higher compared to all fires, but the difference was already small. When the firefighting operation lasted longer, the proportion of fires on public roads was lower compared to all forest fires, and the difference became more pronounced as the duration of the firefighting operation increased (Fig. 5).

Figure 5.

The occurrence of forest fires near public roads against the background of all fires according to the duration of the extinguishing action

A similar relationship to the duration of firefighting operations was observed when analysing the occurrence of fires in relation to the number of rescue and firefighting units involved in the operation (Fig. 6). A higher proportion of the number of fires on public roads compared to all forest fires was found in the fires where fewer than five fire brigades were involved in the operation. For the fires involving more units, the proportion of the number of fires was higher for all fires than for all fires than for fires on public roads.

Figure 6.

Occurrence of forest fires along public roads against the background of all fires according to the number of rescue and firefighting units

In the analysis of the occurrence of forest fires on fire breaks, it is also worth looking at the forest fire hazard category (FFHC) of the individual forest districts in which fires have occurred on fire breaks. The percentage of fires in the fire breaks was practically independent of the fire hazard category (Tab. 1). However, there is a clear differentiation in the percentage of fires on fire breaks by FFHC in relation to the number of forest districts categorised. Although the number of forest districts categorised in the highest and lowest FFHC is similar, the proportion of fires on fire breaks in the highest FFHC category I is clearly higher.

To summarise the analysis of the occurrence of fires on public roads, it can be stated that the special feature of these fires is that they are mostly (almost 90%) fires of ground cover, the average area of which does not exceed 0.05 ha in about 70 of cases. The occurrence of these fires is favoured by a well-developed layer of ground cover, especially grass and heavily weeded cover, as well as dead ground cover covered with litter or grass. Fires on roads are mostly (75%) discovered by bystanders using public roads and, thanks to mobile telephony, the fact of a fire is likely to be quickly reported to the emergency services. This has an impact on, among other things, easier access to the scene of the fire, the short duration of firefighting operations and their effectiveness, as action is taken in the early stages of fire spread. These conditions also have an impact on the lower number of firefighting operations compared to rescue operations deep in the forest. For the other characteristics analysed, the differences are not as clear for fires on roads and in other forests.

The analysis of damage caused by fires in the State Forests was based on data collected in NFFIS for the years 2017–2023. After considering the reports of fires that met the methodological assumptions, 13,436 fires were selected for detailed analyses. Of this, 1,344 fires occurred on public roads, covering an area of 90.48 ha. The remaining fires (12,092) occurred in other forest areas covering an area of 3,143.92 ha. Comparing this number of fires to the area of stands along public roads where paths were created and areas cleared (209,318.42 ha) and the area of other forests (7,406,864.83 ha), the density of fires along roads per 1,000 ha of forest area is 6.42 and for other forests is 1.63. This confirms that fires occur more frequently along public roads than in other forest areas due to easier access to the forest. Of the fires that occurred near roads, 626 had an area of 0.01 ha, representing nearly 50%. However, in terms of losses, 668 resulted in zero losses, which also accounts for nearly 50% of the total number of fires in this group. For fires in forest areas away from roads, 3,626 had an area of 0.01 ha, while 5,225 fires reported no losses. This represents 30% of the fires in this group by area and 43% by loss volume, respectively. These figures indicate a left-skewed distribution; therefore, the nonparametric Mann–Whitney test was used for detailed statistical analysis. The comparison of the rank sum, which was carried out using the Mann–Whitney test, provides a basis for the statement that the size of the fire is significantly dependent on the location of the fire occurrence, because the p-statistic value of this test, which results from the calculations, is 0.00, so that the differences are statistically significant at the assumed significance level of 0.05. Figure 7 shows the distribution of fire size depending on the place of origin, expressed by the median, the 25th and 75th percentile range, as well as the maximum and minimum values for both groups. To improve the readability of the graph, the scale of the Y-axis (fire area) was adapted to the fluctuation range of the fire area along roads. Of the fires that occurred outside the lanes, 119 fires covered an area of more than 3.00 ha, which is shown in the graph. This means that this value accounted for less than 1% of the total number of fires that occurred there, and the largest fire covered 51.40 ha.

Figure 7.

Distribution of the burnt area depending on the place of origin

Losses totalled PLN 813,727.82 from road fires (annual average PLN 162,745) and PLN 26,213,778.82 in other forests (annual average PLN 5,242,755), which, taking into account the number of fires, amounts to PLN 605.45 for road fires and PLN 2,167.86 per fire in other forests. The losses caused by road fires account for only 3% of the total losses caused by forest fires. This means that the losses caused by road fires are on average more than 3.5 times smaller than the losses caused by other fires. Comparison of the rank sum, which was carried out using the Mann–Whitney test, provides a basis for the statement that the losses caused by forest fires depend significantly on the fire location, because the p-statistic value of this test, which results from the calculations, is 0.00, meaning that the differences are statistically significant at the assumed significance level of 0.05. Figure 8 shows the amount of losses caused by fire depending on the location of the fire, expressed as median, 25th and 75th percentiles. To improve readability, the scale of the Y-axis (fire area) in this graph has been adapted to the range of variation in the amount of damage caused by fires near roads. Of the fires that occurred outside the belts, only in 25 cases were the losses greater than PLN 80 thousand, which means that it was about 0.2% of the total number of fires that occurred there.

Figure 8.

Distribution of the amount of damage depending on the location of the fire

According to the General Directorate of State Forests, the total cost of creating and maintaining fire breaks and cleaning up the area in the period 2018–2022 amounted to PLN 35,837,932, which is an average of PLN 7,167,586 per year. Table 2 shows the average annual costs of lanes and clean-up along public roads in the Regional Directorates of State Forests in the period 2018–2022.

The total cost of fire breaks and clearing accounted for 7.02% of the expenditure on fire protection in the State Forests. The largest portion of expenditures was for the removal of fire-hazardous forest materials, which accounted for as much as 78% of the total costs of fire protection on public roads.

The next element of the analysis was to differentiate the costs of establishing new and maintaining existing fire breaks and the costs of clearing public roads according to FFHC. The amount of these costs was related to the forest area of the forest districts. The share of these expenses in the total costs of fire protection is shown in Table 3, while their graphical representation can be seen in Fig. 9.

Figure 9.

Distribution of the share of the costs for the construction of new and maintenance of existing fire breaks as well as the costs for the cleaning of areas near public roads in the total costs of fire protection for forest districts depending on FFHC

The significance of the statistical differentiation of the costs of building lanes and clearing areas along public roads and the proportion of these costs in the total costs of fire protection was determined using the Kruskal–Wallis test, the results of which, expressed by the values of the p-statistic, are shown in Table 4. These data show that this differentiation is not statistically significant.