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Articles containing the keyword 'non-spatial model'
Category : Research article
article id 524,
category
Research article
Timo Pukkala,
Jari Miina,
Marc Palahí.
(2002).
Thinning response and thinning bias in a young Scots pine stand.
Silva Fennica
vol.
36
no.
4
article id 524.
https://doi.org/10.14214/sf.524
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Author Info
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.
-
Pukkala,
University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland
E-mail:
timo.pukkala@joensuu.fi
- Miina, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: jm@nn.fi
- Palahí, European Forest Institute, Torikatu 34, FIN-80100 Joensuu, Finland E-mail: mp@nn.fi
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