THE BIOMASS PRODUCTION OF 3 POPLAR CLONES IN RELATION TO INTERCEPTED SOLAR-RADIATION

The biomass production, in relation to intercepted solar radiation energy, of the poplar clones, cultivars 'Beaupre', 'Fritzi Pauley' and 'Robusta', is compared for stands, grown in containers from cuttings, over one season in Scotland. The 'Beaupre' stand produced 8 t ha-1 of woody biomass, while the 'Fritzi Pauley' and 'Robusta' stands produced 7 t ha-1 and 5 t ha-1 respectively. Although it had the smallest biomass production 'Robusta' had the largest solar radiation conversion ratio, i.e. 0.59 g MJ-1, while 'Beaupre' produced 0. 56 g MJ-1 and 'Fritzi Pauley' 0.47 g MJ-1. The lower production of 'Robusta' was due to late canopy development reducing the total amount of solar radiation intercepted. The results suggest that, of the three clones compared, 'Beaupre' would be the most useful for short-rotation energy forestry in Europe for three reasons. First, it develops its canopy early in the season enabling the capture of the large amount of solar radiation available at that time. Second, it has a high ratio of conversion from solar radiation to dry matter. Third, stem growth continues into November, even in the UK.