Process mechanization models for improved Eucalyptus plantation management in Southern China based on the analysis of currently applied semi-mechanized harvesting operations

Within the last decades ecological and environmental dimensions were in the focus of Chinese forestry and forest research, but forest operations were much less studied. However, a sustainable, efficient, and continuous forest biomass supply is crucial for a socio-economic development in rural areas, and will contribute to national forest management aims. Today, high supply costs and insufficient biomass supply are bottlenecks for bioenergy and wood processing industry in the P.R. China. The aim of this study was (1) to characterize, and obtain process data of the current harvesting operations in forest plantations in Southern China, (2) to develop a harvesting productivity model based on the current performance, and (3) to develop applicable models for improved mechanized operations. The study was conducted in Eucalyptus (Eucalyptus grandis x urophylla) and Mytilaria (Mytilaria laosensis) plantations in steep terrain (8.5–27.5°; respectively 15–52%) in Guangxi province, with a tree diameter at 1.3 m height ranging from 9.8 to 15.4 cm. Via conducting time and motion studies, 237.8 h were recorded and 121.5 m³ were harvested between October 2008 and May 2010. The clear cut operations are characterized by basic manual work, except motor-manual work for tree felling and cross-cutting. The overall time consumption for harvesting and extraction was 115.07 min m^-³, respectively the productivity was 0.58 m³ h^-1. Manual hauling of the logs was identified as the most time consuming activity. Therefore, priority should be given to extraction activities when trying to improve productivity and work safety through mechanization. - Highlights: • Harvesting operations are time consuming, in average 115.1 min m⁻³ (Eucalyptus). • Harvesting operation show limitations for big tree diameter (d_1.3 > 15.1 cm o.b.) • Mechanization of work may solve high costs deficits, and should focus on yarding. • New work concepts, and workers education will have to be developed.