Alina Gerlée

Abstract Although ground mechanised skidding is an economically efficient method of timber extraction, it brings several negative consequences to the natural environment. According to the literature, out of all the different forest operations, it is timber extraction (skidding) and the associated presence of forest roads and skid trails that contribute most to soil compaction, increased erosion, surface runoff and flash floods (see Affek 2019 for review). The objective of our study was thus to assess the size of environmental impacts of logging in the eastern part of the Polish Carpathians with more accuracy and a broader scope than has been achieved before (the results of the first phase of this work being published in Forest Ecology and Management; Affek et al., 2017). To this end, we took twice as large a sample of forest divisions and calculated the density of forest roads and its links to topography. We also estimated the range of any potential edge effect caused by forest roads, and supplemented our analysis with a description of the methods and intensity of timber harvesting in the study area. Within the 15 Forest Districts analysed (comprising 2639 km2 of forested area), we randomly selected 120 Forest divisions (covering 48 km2 in total) for analysis. We used the national LiDAR dataset of countrywide coverage (point density of 4 per m2) to detect forest roads and skid trails. The total length, mean density, mean and maximum inclination, and mean coverage of forest roads were calculated, while the potential combined edge effect of these was also determined. These data were linked with official forest spatial data regarding forest management practices, forest types, age of stands and planned cuts, as well as relevant policy documents, reports and scientific literature. We demonstrated that the mean density of forest roads in the 120 forest divisions selected is 12.48 km/km², including paved and unpaved roads and skid trails. The estimated density for the eastern part of the Polish Carpathians is in the range 11.43-13.53 km/km² (with 95% probability). The obtained confidence interval was lower by 35% when set against the one derived from the analysis of 60 Forest Districts. The length of the entire road network was an estimated 30166-35706 km, equating to some 4.6-5.4% of the forest area being covered by roads. Maximum road inclination in the sampled forest divisions ranges from 9 to 38°, while about 8% of forest roads lead through slopes of more than 20°. Ground skidding by means of skidders, forwarders and agricultural tractors adapted for logging is the most common method of timber extraction in the Polish Carpathians. The total volume of the harvest in the analysed 15 Forest Districts in 2016 was of a planned 1,230,153 m3, equating to an average harvest of 4.62 m3/ha. The most common types of treatment for the current 10-year periods are: late and early thinning (38.5% of the area), gradual thinning improved (35.6%) and early and late cleaning (7%). We concluded that the LiDAR-assessed density of Carpathian logging roads (including skid trails) is among the highest reported in the literature, which translates into disturbed soil structure over approx. 5% of the entire area analysed. The density of forest roads is not related to slope steepness, but the same density of roads in steep terrain obviously has a far greater impact on erosion and sediment transport than is the case in more gentle terrain. The selective harvesting method used today in the Carpathians requires frequent entry of heavy equipment (skidders, forwarders or tractors) into large forest areas, hence skidding now appears to be a bottleneck for sustainable forest management in the Carpathians. One of the possible solutions leading to a more sustainable management of forest resources in the mountains is thus the replacement of ground skidding with environment-friendly cable cars.

Keywords: drogi leśne, zrywka, LiDAR, erozja, efekt brzegowy, Karpaty Wschodnie

Andrzej Affek [a.affek@twarda.pan.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Twarda 51/55, 00‑818 Warszawa, Poland
Maria Zachwatowicz [m.zachwatowicz@uw.edu.pl]

Citation

APA: Affek, A., Gerlée, A., Sosnowska, A., & Zachwatowicz, M. (2019). Oszacowanie skali wpływu pozyskiwania drewna na wybrane elementy środowiska we wschodniej części polskich Karpat. Przegląd Geograficzny, 91(1), 83-106. https://doi.org/10.7163/PrzG.2019.1.4
MLA: Affek, Andrzej, et al. "Oszacowanie skali wpływu pozyskiwania drewna na wybrane elementy środowiska we wschodniej części polskich Karpat". Przegląd Geograficzny, vol. 91, no. 1, 2019, pp. 83-106. https://doi.org/10.7163/PrzG.2019.1.4
Chicago: Affek, Andrzej, Gerlée, Alina, Sosnowska, Agnieszka, and Zachwatowicz, Maria. "Oszacowanie skali wpływu pozyskiwania drewna na wybrane elementy środowiska we wschodniej części polskich Karpat". Przegląd Geograficzny 91, no. 1 (2019): 83-106. https://doi.org/10.7163/PrzG.2019.1.4
Harvard: Affek, A., Gerlée, A., Sosnowska, A., & Zachwatowicz, M. 2019. "Oszacowanie skali wpływu pozyskiwania drewna na wybrane elementy środowiska we wschodniej części polskich Karpat". Przegląd Geograficzny, vol. 91, no. 1, pp. 83-106. https://doi.org/10.7163/PrzG.2019.1.4