Open access publications in the SLU publication database

Abstract

This thesis summarizes and discusses results of four studies regarding the effects of growing Scots pine (Pinus sylvestris L.)in containers on root deformation, tree stability, basal sweep- and compression wood formation. The thesis is based on non-experimental surveys that include young (7- to 9-year-old) and older (19- to 24-year-old) Scots pine trees from naturally regenerated stands and from stands established with container-grown (Paperpot) seedlings. The thesis is also based on data obtained from 6- and 22-year-old trials with Scots pine seedlings reared from containers of different design. Results showed that root morphology, mechanical tree stability and stem straightness of container-grown Scots pine trees will improve over time and approach the state of naturally regenerated trees. However, inside the root system fibre disturbances as well as bark remains still occur. Root deformation caused by improper design of containers may lead to mechanical tree instability and leaning trees, which will cause compression wood formation. For 6-year-old Scots pine trees, the correlation between basal sweep and compression wood content was strong. No correlation between these variables was obtained for older trees that had become straighter over time. Therefore, the straightness of a stem is not per se a reliable measure of occurrence of compression wood within the stem. Because the formation of compression wood in the basal part is ongoing as long as trees are not completely straight, it is difficult to forecast the future quality of such logs. This thesis shows that container design affects root development, which can subsequently influence the formation of basal sweep. The stem form of Scots pine can be improved by the use of a container type that promotes a more natural root morphology, especially in fertile sites with dense soil types.