Effects of pruning of vertical roots on growth of one-year Scots pine (Pinus sylvestris L.) seedlings in the first year after transplanting

The research was carried out in 2006 within the area of forest nursery in Okalewo, the Forest Inspectorate Skrwilno (Central Poland, at 53º02´N, 19º23´E). The aim of the study was to determine the effects of root pruning in one-year Scots pine seedlings (Pinus sylvestris L.) on their growth after transplanting. The vertical roots of one-year Scots pine seedlings were pruned to the length of 5, 10, 15 i 20 cm and measured. The scope of measurements included: stem length and thickness, total root length, root length within thickness classes, surface root area, root volume as well as the number of root tips and ramifications. The measurements of root systems were performed with the use of a scanner and WinRhizo software. The seedlings were transplanted and were growing in the nursery all through the vegetation season 2006. In October of this year the seedlings were lifted from the ground and measured again at the same scope. Reiterated measurements allowed evaluation of increment characteristics after transplanting. The results indicated negative impacts of intensive root pruning before transplantation on seedling survival rates. Severe pruning of seedling vertical roots had negative effects on increment gained by both above- and underground seedling parts. Pruning roots to 5 cm of length significantly decreased pine seedling survival rate of. On the other hand, 20 cm long roots have no significant effects on seedling survival and increment but they can cause difficulties in seedling nursery cultivation.