Current issue: 53(4)
Under compilation: 54(1)
The concept of tree class as indicated by dominant, codominant, intermediate and suppressed trees is analysed using empirical material representing 13 younger Scots pine (Pinus sylvestris L.) stands. The relative needle biomass, i.e. the needle biomass related to the maximum needle biomass in the stand, was closely related to the relative height of the tree and independent of the stand characteristics. Furthermore, the relative illumination of the crown system was related to the relative height of the trees as well as the relative photosynthetic capacity and tree-to-tree variation in growth. When calculated per needle biomass unit it appeared that height growth, radial growth, needle growth and other growth parameters were the highest in the suppressed trees. The suppressed trees thus appear to be more efficient in utilizing available resources than other tree classes. The ecologic significance of the results is discussed.
The PDF includes a summary in Finnish.
The Forest Research Institute of Finland has established permanent sample plots to survey the effect of thinnings on the stands. This study compares the development of tended and natural Scots pine (Pinus sylvestris L.) stands growing on three different forest types: Oxalis-Myrtillus, Vaccinium and Calluna site type. The effect of heavy thinning from below (Oxalis-Myrtillus and Vaccinium site types) and increment felling (Calluna site type) was assessed by dividing the trees of the stands in tree classification classes according to their crown storey and defects.
The results show that thinning from below and increment thinning increase the proportion of trees in the 1st crown storey, which is already large in the natural stands. Also the diameter distribution is more even and the mean diameter higher after the thinnings.
In Scots pine stands in natural state, volume increment per stem is highest in the 1st crown storey and diminishes strongly towards the lower crown storeys. Thinnings increased the increment. The study indicates that many of the objectives of the intermediate cuttings, including promoting the growth of the best trees and improving the quality of the stand, have in general been achieved. Consequently, the thinnings give means to achieve the most valuable yield in the stand.
The article includes a summary in English.