Estimation of Productivity and Costs of Using a Track Mini-Harvester with a Stroke Head for the First Commercial Thinning of a Scots Pine Stand

Grzegorz Szewczyk,Paweł Tylek,Dariusz Kulak,Arkadiusz Stańczykiewicz,Krzysztof Leszczyński

doi:10.3390/f12070870

Abstract

The aim of the present work was to estimate the productivity and costs of timber harvesting and forwarding during the first commercial thinning of a Scots pine stand. Three harvesting models were introduced and compared: narrow trail, wide access trail, and schematic extraction. The analyzed harvesting equipment consisted of a track mini-excavator (34 kW) with a stroke harvester head (gripping range 4–30 cm), and a farm tractor coupled to a logging trailer with a hydraulic crane. Merchantable timber (roundwood with a minimum diameter of 5 cm inside bark) was harvested from a 25-year-old planted Scots pine stand growing on a grid of 1.4 m × 1.8 m. The study showed the productivity of the mini-harvester ranged from 3.09 to 3.47 m3/PMH15 (productive machine hours plus 15 min), and that of the forwarding equipment to be 4.07 m3/PMH15. The analyzed model of productivity as a function of tree volume and thinning intensity was statistically significant, but the intensity parameter was significant only on plots located along wide access trails (3.7 m) and insignificant on plots located along narrow access trails (2.5 m). The distance between trees was not found to be significant. The calculated net machine costs for the forwarding equipment and track mini-harvester were EUR 36.12 and 52.47 per PMH, respectively. An increase in the usage rate of the harvesting equipment to 80% would reduce the harvesting and forwarding costs to EUR 22.07/m3.

Highlights

IntroductionAccording to the State of Europe’s Forests report [1], Poland has a relatively large forest area (9.4 million ha) with a growing stock density higher than the European average (269 m3 /ha)
Taking into consideration different climate change scenarios [2], it is estimated that the highest productivity of Scots pine stands can be achieved with medium thinning (20–40%)
Analysis of marginal productivity functions (Figure 3) showed higher average 9 of 13 productivity for sample plots along the wide access trails (AT35; R2adj. = 0.5192, F = 8.304, p = 0.008) at thinning intensity greater than 23%, while at lower thinning intensity higher productivity was observed sample plots along narrow access trails

Summary

Introduction

According to the State of Europe’s Forests report [1], Poland has a relatively large forest area (9.4 million ha) with a growing stock density higher than the European average (269 m3 /ha). This translates into a growing stock volume of over 2.5 billion m3 , offering a vast source of wood for the region. Most of Poland’s forests are publicly owned (80.8%), including forests managed by the State Forests National Forest Holding (77.0%) Among the latter, the largest area, ~4 million ha, contains stands of 20–80-year-old trees, representing almost 60% of the available wood stock. Taking into consideration different climate change scenarios [2], it is estimated that the highest productivity of Scots pine stands can be achieved with medium thinning (20–40%)

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Discussion

Conclusion