The effects of thinning on a spruce stand, over a period of 40 years of monitoring

This survey is based on an experiment conducted by the National Institute for Research and Development in Forestry (ICAS) Câmpulung Moldovenesc in the period of 1974-2004. The experiment consisted of 8 experimental areas, where thinnings of different intensities were performed (years 1974, 1979, 1984, 1989, and 2004). The personal contribution consisted in the inventory from 2010, the analysis and interpretation of personal data and of data taken from other sources. The aim of this paper is to outline the influence of thinning intensity and the evolution of the spruce stand in time, in terms of structure, productivity and stability. Therefore, it appeared that the heavy thinning has significantly influenced the spruce stand. The stand average diameter has registered a higher growth in the areas with moderate and heavy areas, due to higher extraction intensity, that reduces the competition for sunlight, highlighting the diameter growth. The heavy thinnings have influenced the average height, as it has indicated lower figures, due to the competition for sunlight and the higher increment. The improper values of the number of trees, the spacing factor, the density factor, the total production, indicate the destructuring of the stand for 2010 in the heavy thinning areas. The implementation of thinnings had a negative effect on the stand, especially in the heavy thinning areas, leading to its destablishing.It can be concluded, that for the studied stand after the age of 30, light thinnings were recommended. These aspects are outlined by means of the productivity analysis and of the current structural parameters from the control area, where this type of thinning intensity was implemented