This project developed a cost model for the mechanical harvesting of fast-growing Eucalyptus plantations. with such a model, forest managers can check the profitability of a prospective operation under different work conditions and assess the competitiveness of alternative options, which in turn will lead to supply chain optimization. The model is based on mathematical relationships that return machine productivity as a function of operational conditions. These relationships were calculated on data obtained from detailed time studies, conducted on all the main equipment types used in Eucalyptus plantations. Tests were conducted on 11 different machines that harvested a total 2465 oven-dry tonnes over 23 ha on 12 sites in 3 countries. The time study sessions lasted 250 h. Both the Cut-to-Length (CTL) system and the Whole-Tree (WT) system were studied. The model was validated with success and was used to make a number of different simulations. Simulation results show that the WT system allows cheaper harvesting and transport than the CTL system for a range of conditions. Under the conditions of our simulations and in favourable terrain, WT harvesting results in a delivered cost of about 20 euro/green tonne of bark-free pulp chips, whereas CTL harvesting results in a cost between 25 and over 30 euro/green tonne of debarked pulp roundwood. (C) 2009 Elsevier Ltd. All rights reserved.