%0 Research article
%T Thinning response and thinning bias in a young Scots pine stand
%A Pukkala, Timo
%A Miina, Jari
%A Palahí, Marc
%D 2002
%J Silva Fennica
%V 36
%N 4
%R doi:10.14214/sf.524
%U https://silvafennica.fi/article/524
%X The study analyses the annual post-thinning response and thinning bias  of a young Scots pine stand as a function of tree size, competition  faced by the tree, and competition that is removed around the tree in  the thinning treatment. The thinning response of a tree was defined as  the change of tree growth due to a thinning treatment. The thinning bias  was defined as the difference between the true growth and model  prediction. A distance-dependent (spatial) and a distance-independent  (non-spatial) growth model were used in the calculations. The empirical  data were measured from a thinning experiment consisting of ten plots,  each 40 x 30 m in size, which were thinned to different stand densities.  The ten-year post-thinning growth of every remaining tree was measured.  The results indicated that the highest thinning response is among  medium-sized and co-dominant trees. The thinning response is quite  small, and even negative for some trees, for two years after thinning  but it becomes clearly positive from the third year onwards. The spatial  model underestimated the growth of small trees (which usually face high  competition) while the non-spatial model overestimated the growth of  trees that are small or face much competition. The spatial model used in  this study overemphasized the effect of competition while the  non-spatial model underestimated this effect. Both growth models  overestimated the growth of trees in heavily thinned places, but this  bias disappeared in two years. The negative bias was more pronounced  with a spatial growth model because the tendency of the non-spatial  model to underestimate the growth of trees facing little competition  partly compensated for the negative bias.