In Italy, short rotation coppice (SRC) has become very popular in recent years, with over 4000 ha already planted - almost exclusively with clonal poplar. Commercial harvesting operations are dominated by modified foragers, equipped with dedicated SRC headers. At present, contractors use two main header types: German Claas HS-2 and Italian GBE. The former fits smaller foragers with a power below 300 kW, the latter is used on larger harvest units. This study models the performance of modified foragers on a range of short-rotation poplar plantations. Data were collected from 45 operations, covering a total of 118 ha and producing over 4400 green tonnes of wood chips. The average yield of the fields harvested during the trials was about 23 gt ha(-1) year(-1) (at a moisture content of 59%), and machine productivity ranged from 9 to 70 green tonnes per scheduled machine hour (gt SMH-1), with an average value of 35 gt SMH-1. A model was developed to predict harvesting performance and cost, showing that harvesting cost can be maintained below the 15 (sic) gt(-1) (2 (sic) GJ(-1)) level, if field stocking exceeds 40 gt ha(-1). (C) 2009 Elsevier Ltd. All rights reserved