Evaluation of Salvage Logging Productivity and Costs in the Sensitive Forests of Bulgaria

Stanimir Stoilov,Georgi Angelov,Andrea R Proto,Stelian Alexandru Borz,Salvatore F Papandrea

doi:10.3390/f12030309

Stanimir Stoilov, Georgi Angelov + Show 3 more

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https://doi.org/10.3390/f12030309

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Abstract

Steep terrain harvesting can only be implemented by a limited set of operational alternatives; therefore, it is important to be efficient in such conditions, in order to avoid incurring high costs. Harvesting abiotically-disturbed forests (salvage harvests caused by wet snow), which is becoming common these days, can significantly impact the operational efficiency of extraction operations. This study was implemented in order to evaluate the performance of truck-mounted uphill cable yarding operations in salvage logging deployed in coniferous stands. A time study was used to estimate the productivity and yarding costs, and predictive models were developed in order to relate the time consumption and productivity to the relevant operational factors, including the degree of wood damage. The average operational conditions were characterized by an extraction distance of 101 m and a lateral yarding distance of 18 m, resulting in a productivity rate of 20.1 m3 h−1. In response to different kind of delays, the productivity rate decreased to 12.8 m3 h−1. Under the prevailing conditions, lateral yarding accounted for 32% of the gross work cycle time, and for 50% of the delay-free work cycle time of the machine. Decreasing the lateral yarding distance and increasing the payload volume to the maximum capacity of the machine would eventually lead to a yarding productivity of close to 30 m3 per SMH (scheduled machine hour). The calculation of the gross costs of uphill yarding showed that the labor costs (35.7%) were slightly higher than the fixed costs (32.9%), and twice as high compared to the variable costs (17.7%). The remote control of the carriage, mechanical slack-pulling mechanisms, and radio-controlled chokers are just some of the improvements that would have led to increments in operational efficiency.

Highlights

Abiotic and biotic factors are causing important damage in European forests, and windstorms are the dominant factor causing them [1]
(33%) of the delay-free work cycle time was spent during the lateral outhaul and hooking, with some differences that were characteristic to each corridor (A, 28%; B, 36%; C, 24%), followed by the lateral inhaul
Large-scale windstorms are increasingly frequent in European forests, and they may cause important losses, especially when they affect sensitive forests, for which there are problems related to the wood’s recovery

Summary

Introduction

Abiotic and biotic factors are causing important damage in European forests, and windstorms are the dominant factor causing them [1] Such forest disturbances are becoming common due to the current trends in the climate, and their severity has increased in many forest ecosystems, including those in the Northern Hemisphere [2]. Wet snow and ice cause damage to forests by bending or breaking the tree branches and tops This happens when the weight of frozen precipitation exceeds the buckling load of the tree part bearing the load. In such circumstances, bending can occur, and it can result in permanent internal wood damage without any external exhibition of such damage. A common way to minimize these effects by forest management is salvage logging [2], an activity that gained considerable interest and importance in those cases when disturbances occur in sensitive forest areas, and which is needed in recovering the economic value of timber in damaged forests, even in those locations which otherwise are spared from regular logging [3,4]

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