Seventeen different poplar (Populus) clones were studied during the first growing season of the second rotation of a high-density coppice culture. In August 2001, total leaf area (tLA), number of leaves and specific leaf area (SLA) were determined for 15 shoots per clone. Above-ground woody biomass production and leaf area index (LAI) were estimated by using allometric relationships and an up-scaling approach. Significant clonal variation was observed in LAI, biomass production, tLA and number of leaves per basal shoot area. Biomass production ranged from 3 to 8 Mg ha(-1) y(-1) and LAI ranged from 2 to 6 m(2) m(-2). The LAI, tLA per shoot, and SLA were the most important determinants of above-ground woody biomass production. The production of many small leaves was shown to give a similar biomass production as the production of few but large leaves. (C) 2003 Elsevier Ltd. All rights reserved.