Cost evaluation of three ground-logging methods in a mixed broadleaved mountainous forest

Aim of study: To compare cost and productivity of three ground-based logging methods by skidder: 1, tree length method (TLM), 2, long length method (LLM) and 3, short length method (SLM). Area of study: A mixed broadleaved mountainous forest stand in the Hyrcanian forests in northern Iran. Material and methods: To develop time prediction models, all measurements of time were replaced by their decadic logarithms, and on the basis of the developed models, we simulated cost of 11 skidding turns depending on the diameter of the log (DL), skidding distance (SD), and the winching distance (WD) for TLM, LLM, and SLM. Main results: Our results demonstrated that on average the net costs per extraction of one cubic meter wood (m3) were 3.06, 5.69, and 6.81 €/m3 in TLM, LLM, and SLM, respectively, and the most economical alternative depending on DL, SD and WD was a TLM. Furthermore, the results of simulated models suggest that as long as the diameter of the felled trees is less than 40 cm, the cut-to-length system is not an economical alternative. The cut-to-length method can be applied for trees with larger diameter (more than 40 cm), and in short skidding distance SLM is preferable to LLM but in cases of long skidding distance, LLM is more economical than SLM. Research highlights: DLand SD were the main causes which influenced the productivity and cost of ground-based logging methods