The intensity of wildfires is projected to increase with the rising frequency of droughts due to climate change. Management practices following forest fires must include restoring the appropriate species composition. This study was performed within the wider context of the regeneration of soil properties, including the stock and soil organic matter (SOM) content, at the largest forest fire site in Poland (more than 9000 ha) in the Rudziniec Forest District, Upper Silesia. Research plots were established on sandy soils (Podzols and Arenosols) in pure stands of Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth), and black alder (Alnus glutinosa (L.) Gaertn.). The organic and mineral soil horizons were sampled from each research plot and control plots unaffected by the fire. The trees’ foliage was also sampled to determine the nutrient supply. Basic soil properties were determined, including the texture, pH, bulk density, organic carbon (C), macronutrient contents, soil microbial biomass, and labile C and nitrogen (N) fractions. We found that, 30 years after the fire, the post-fire soils had similar SOC stocks (34.80 Mg ha⁻¹) to the control plots (31.72 Mg ha⁻¹); however, they differed in their stocks of labile C and N fractions. The post-fire soils had a less stable C pool due to a higher stock of the fraction associated with particulate organic matter. In contrast, the N pool was more stable in the post-fire soils than in the control soils due to a lower contribution of the most labile fractions. The soils under Scots pine had the least stable SOM, which may have influenced the intensification of the podzolization process, whereas the highest biomass of soil microorganisms was observed under common birch. The soils under black alder had the highest acidity and lowest phosphorus (P) content. The C:N:P ratios in the post-fire soils and tree foliage indicated that P may have been the limiting factor in alder growth, and N for pine and birch. Our findings indicate that tree species composition is an important factor in the recovery of post-fire soil properties. However, the introduction of pure black alder stands to post-fire soils with low moisture and P availability showed little effectiveness in restoring the SOM content and N pool.

Road networks providing access to forest stands, including integral parts such as timber yards, are subjected to significant loads from timber-transporting vehicles. These loads act on the road surfaces, causing them to deform. This study measured and compared the extent of deformation at two timber yards in the mountain forests of southern Poland in the Western Carpathians. These surfaces were constructed as: crushed stone (timber yard in the Ustroń Forest District) and earth (Forest Experimental Station of the University of Agriculture in Kraków). The measurements were carried out using photogrammetric techniques based on aerial surveys by an unmanned aerial vehicle. The measurements were based on networks of reference points with coordinates in local coordinate systems. During the period between the flights, timber was being stored, handled and transported at both sites. The forest administration provided data on the volume of timber delivered to and removed from the storage yard, as well as basic information on the transport vehicles. Soil samples were taken from the surface of both storage yards for laboratory analysis to illustrate working conditions—the soil type, current moisture content, organic matter content and filtration coefficient (from the soil particle size distribution curve) were determined. Digital terrestrial model (DTM) rasters obtained from both aerial surveys at each storage yard were used to calculate differential rasters, which were analysed by plotting cross-sections at selected locations and directions and by calculating the volume of changes in surface geometry between the survey dates. The observed depths of ruts reach 0.4 m at the Ustroń storage yard and 0.5 m at the LZD storage yard, whilst changes involving the displacement of soil from the ruts above the previous surface level are 0.3 m at the Ustroń storage yard and 0.4 m at the LZD storage yard. Greater deformation was observed on the earth surface (with a high organic content and poorer drainage) than on the crushed stone surface, even though the latter was covered by an uncleared layer of mud and waste left over from timber handling. Given the two-site, single-cycle design of this study, this pattern is consistent with—but cannot on its own confirm—a stabilising effect of surface reinforcement; differences in soil moisture, organic content and observation period between the two sites may also have contributed and could not be separated from the effect of surface type alone.