Basal sweep and compression wood in young Scots pine trees

This study demonstrates the correlation between stem form and compression wood content in 36 sampled trees from a 6-yr-old container grown Scots pine (Pinus sylvestris L.) plantation in central Sweden. Root analyses were carried out to examine causes for the high incidences of basal sweep. On the sampled trees basal sweep, stem sweep and maximum bow-height were measured. Discs were cut at different heights and the compression wood content was analysed using digital image analysis. Pith eccentricity and out-of-roundness were calculated for each disc as well as per stem. Compression wood and pith eccentricity was most pronounced near the stem base, where sweep tends to be high. In general, pith eccentricity increased with degree of basal sweep. As a conclusion, expression of basal sweep can be used to predict compression wood content in young Scots pine trees. This study also shows the importance of anchoring of a tree to prevent basal sweep formation due to instability.