The influence of soil conditions, with focus on soil acidity, on the establishment of poplar (Populus spp.)

The interest for fast growing poplar species has increased, but the establishment on forest soils can be disappointing. One explanation could be low pH-levels. Thus, the main purpose of this study was to test the development of available poplar clones on soils with different soil acidity. The study was divided into two parts. In study A, poplar cuttings were planted in peat soil with pH-levels ranging from 3.4 to 5.7. In study B, the same plant material was planted in forest soils collected from different sites with different pH levels. Both studies were carried out in a greenhouse. Soil acidity had a significant effect on plant development. With increasing pH, height and biomass of the poplar clones increased. A difference in allocation between root and aboveground biomass was seen among treatments with more biomass directed above ground at higher pH. This pattern was more pronounced with increasing plant weight. Less Al and more Ca were found in leaves from plants grown in soils with higher pH, but P was low overall in the forest soil. Results from this study show that low pH-values can hamper the establishment of poplar. The availability of Ca, P and Al is also of importance, since they could counteract or increase the adverse effects of low pH-levels.