Original article Effects of seedling density on the growth of Corsican pine (Pinus nigra var. maritima Melv.), Scots pine (Pinus sylvestris L.) and Douglas-fir

Abstract- Corsican pine, Scots pine and Douglas-fir seedlings were grown in containers at a con-stant volume at densities ranging from 100 to over 1 000 plants m-2. Both shoot and root dry weight of each species decreased with increasing density, especially at densities greater than 500 m-2. In contrast, shoot height of Corsican and Scots pine increased at high densities, but the height of Douglas-fir was unaffected by density. Shoot height was not correlated with dry weight in Douglas-fir and Scots pine, and was negatively correlated in Corsican pine. Root collar diam-eter was positively correlated with seedling weight in all three species. Increasing the volume of tray cells only increased seedling size in Douglas-fir at densities lower than 400 m-2. Survival of outplanted Douglas-fir seedlings was reduced in plants grown at the highest density (1 550 m-2). Height and diameter increments were greatest in plants raised at intermediate densities around 780 m-2. (© Inra/Elsevier, Paris.