Growth Performance of Hybrid Poplars (Populus × canadensis Moench) in the Danube Floodplain, Southern Romania

Abstract

Clonal plantations of hybrid poplars (Populus x Canadensis Moench) play an important role in the silviculture of many European countries. The choice of hybrid clones to be used in a certain geographic area is of critical importance for the production and stability of plantations. The performance of seven clones of hybrid poplar was evaluated in one experimental plot (Boianu) situated in the Danube floodplains, in southern Romania. We found substantial differences in biomass production between the hybrid clones at 15 years after planting. Clone ‘Sacrau 79’ confirmed its high-growing capacity and relatively constant growth rate. Clones ‘I-154’ and ‘Veneziano’ performed well and reacted positively in a more open stand after thinning. The biomass production of clone ‘I-214’ was less than the overall average value. A positive and significant correlation was observed between stomatal density and crown size. The stomatal density on the lower surface of the leaf showed a greater influence on biomass production than the density on the upper surface of the leaf. Our results support the importance of periodical measurements in comparative field trials, due to the different temporal growing dynamics of hybrid poplar clones.