Growth analysis of Scots pine and lodgepole pine seedlings

Possible reasons for the superior growth rate of lodgepole pine (LP) (Pinus contorta Dougl. var. latifolia Engelm.) compared to Scots pine (SP) (Pinus sylvestris L.) were investigated in a trial where the species were grown in large pots with sand, till or topsoil, during 4 years following sowing. Although starting with lower seed mass, LP seedlings had greater mass than those of SP at the end of the study period. There was, however, a species x growing media interaction and the difference in final mass was greatest for seedlings growing in topsoil. Growth analyses showed that the faster relative growth rate in LP seedlings was linked with a higher leaf area ratio, specific leaf area and nitrogen use efficiency. A higher relative allocation to thin roots was another trait of LP that may contribute to its superior productivity. The fast root growth suggests shorter cultivating time of potted LP seedlings to avoid root deformation. SP allocated relatively more to stem and thick roots, components associated with physical stability. There was no species difference in allocation to needles when relating to total biomass, but LP had a larger proportion of needles in relation to above-ground biomass.