Sites of maximal potential for poplar cultivation

Abstract

The main site factors significant for the utilisation of the maximal genetic potential of black poplars were studied. Black poplar occupies natural sites in the complex of alluvial hygrophilous forests, in the zone of narrow belts in river inundation, with sudden changes of micro-relief, differences in soil and hydrologic regime. The soils which are naturally occupied by black poplar are of the fluvisol and humofluvisol types. The most significant factor for the expression of poplar genetic potential is the content of the fraction silt+clay. In addition to the above, significant factors are the thickness and distribution of layers and horizons, humus content, flood frequency and duration, level of ground water. Populus x euramericana cl. I-214 showed the maximal yield of 36 m³/ha average volume increment for 20 years on the soil with average silt+clay content from 30 to 50%, while some eastern cottonwood Populus deltoides cultivars of same age have average increment from 30 to 40 m³/ha, but on the soils with somewhat higher content of silt+clay fraction.