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Knowing the Norway spruce stands dynamics of under the management intensity influence through the long-term experimental plots has a multitude effects, from scientific point of view, to substantiate decisions in various areas of activity specific to the environment. The research was carried out in three long-term experimental plots in which were placed, three variants of silvicultural work (control, moderate, forte) to reveal the influence of thinning on biometric characteristics and to the development of even Norway spruce stands. This paper reveal specific research aspects, as follows: (i) number of trees·ha-1; (ii) distribution of the number of trees by diameter categories; (iii) the DBH; (iv) the height corresponding to the DBH; (v) the quality of the trees in the experimental plot variants; (vi) basic distribution statistics (average, standard deviation, minimum, maximum, asymmetry, excess). In the Norway spruce stands studied, the effect of the silvicultural works on the DBH, applied in the strong variant, compared to the control variant (where no silvicultural works were performed), is manifested by its superiority, with values between 4% and 13%. The superiority of the height corresponding to the DBH, applied in the strong variant, compared to the control variant, is manifested with values between 1% and 11%. From the point of view of the distribution of the number of trees by diameter categories, the theoretical Beta distribution best achieves the adjustment of the experimental distribution. In the control variants, the influence of snow and wind are the same effect with the moderate and strong interventions of silvicultural works in the plot variants. The Norway spruce trees quality indicates that trunk rot is present in a proportion between 1% and 7% of the trees number. The damages caused by the logging process (a factor favoring the appearance of root rot) affected a number of trees between 9% and 49%. The dynamics of some structural parameters in Norway spruce stands under the influence of the silvicultural works showed the effect on the tree’s development as well as the complexity of the factors to be taken into account to establish the most efficient methods and models for Norway spruce stand management in risk areas. [ABSTRACT FROM AUTHOR]

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The quality assessment of the Norway spruce trees by non-destructive methods and techniques is necessary in the forestry field for the tree degradation and quality estimation. The research material consisted of two permanent experimental plots installed in Norway spruce stands, in a representative area in terms of the action of biotic and abiotic factors on wood quality. To assess the quality of Norway spruce trees through non-destructive methods and techniques, 398 trees were investigated. There have been approached researches on the frequency of the trees with root rot, the resistance to micro-drilling of the wood with decay and the density of rotting wood. The results obtained showed that in some Norway spruce stands the frequency of the trees with root rot identified with Rotfinder device has significant values (16%). Also, trees with trunk rot caused by deer wounds, affect quality timber and decrease stand stability. The relationship between the value indicated by the Rotfinder device and the proportion occupied by root rot in the Norway spruce trees cross section is given by a logarithmic equation. The average density for Norway spruce wood with rot, obtained by current research, is 0.365 (0.351 is the value for root rot and 0.375 for trunk rot). The resistance value of the micro-drilling wood rot, increases as the density of the wood increase according to an exponential equation. The results obtained are a practical importance because estimations can be made for different forest areas of the root rot proportion in cross-section area. Also, expeditious and accurate wood quality estimates can be made according to the resistance value indicated by the Resistograph device. [ABSTRACT FROM AUTHOR]

Recent studies have given more emphasis to mixed stands, highlighting the importance of species diversity, their growth and development are an important subject of research, given the advantages of the functions and services offered. The research material consisted of three representative experimental plots installed in mixed stands of Norway spruce, Silver fir and European beech. Researched aspects related to stand density, species proportion, stand composition, horizontal spatial model, vertical model, dimensional parameters distribution in the stands, and the homogeneity of the stands were addressed. The density of the Norway spruce, Silver fir and European beech mixed stands shows that the number of trees·ha-1 range between 336 and 760, the basal area·ha-1 between 38.5 m2 and 41.2 m2 and the volume·ha-1 between 570.0 m3 and 651.4 m3. Horizontal spatial tree pattern is an important attribute of the stands structure that provides an idea of the variation of tree spacing and has a direct ecological influence in many processes in forest ecosystems. The vertical structure of the mixed stands is directly related to the main processes in the dynamics of the tree, being closely related to the capacity of the adaptation of ecosystems against abiotic disturbing factors. The distribution of dimensional parameters in a stand can be understood as a property that detaches from the data of individuals, therefore, represents an intermediate scale between the tree and the stand. The use of uni-modal statistical distributions when attempting to apply distribution patterns to characterize the distribution of the number of trees by diameters can lead to simplistic descriptions, altering the characterization of the stand structure. In the Norway spruce, fir and European beech mixed stands, the high degree of structural heterogeneity is highlighted. The results obtained showed that mixed Norway spruce, fir and European beech stands can develop in a fundamentally different way, the regeneration mode as well as the different growth characteristics of the component species having a significant influence. [ABSTRACT FROM AUTHOR]

Productivity of forest ecosystems can be assessed by two categories of methods based on earth characteristics or plant-based characteristics. The research material, in present paper, consist of ten permanent experimental plots installed in representative mixed forests of Norway spruce, Silver fir and European beech, in the northern Carpathians, aged 75 to 125 years. Research issues related to some productivity indices, i.e. net primary productivity (average increase of main production), height corresponding to a reference diameter, dominant height, Eichhorn's rule were addressed. The results obtained showed that the average increase of the main production varies between 5 m3an-1ha-1 and 10 m3an-1ha-1. As the age of the stands (x) increases, the average of the main production (y) decreases, according to a power regression equation of y = axb. The relation between the species proportion involved in the mixture (by volume) (x) and the average increase of the main production of the species (y) is given also by a power regression equation of y = axb. The height corresponding to the reference diameter of 50 cm shows average values over 33 m for the analyzed species (MO, BR, FA) and the corresponding diameter of 25 cm has average values greater than 22 m. In researched mixtures from the north of the Eastern Carpathians the dominant height for the Norway spruce species varies between 37 m and 48 m, for the Silver fir tree between 37 m and 50 m and for the European beech species between 28 m and 38 m. The relation between the height (x) and the volume corresponding to the species, respectively the total volume (y) (Eichhorn rule), in analyzed mixtures, is given by an exponential regression of the form y = aexb. [ABSTRACT FROM AUTHOR]

The promotion of mixed stands has been identified as an adaptation strategy in forest management to cope with climate change. The researches focused on some indicators of forest dynamics to stand level in mixed forests of Norway spruce, Silver fir and European beech with reference to the growth dominance coefficient, the growth-size relationship, respectively to the distribution of the volume and the increase in the basal area by diameters. The research was developed in eight permanent experimental plots of the Production Unit I Demacușa, the Tomnatic Experimental Base. The analysis of the growth dominance coefficient, in stands older than 80 years, shows that the larger trees represent proportionally less, in terms of growth, than the mass at the researched stands level of the Norway spruce, Silver fir and European beech. The reversal growth dominance could result from accelerating the growth of non-dominant trees, the declining growth of dominant trees, the increasing the proportion of dominated trees or a combination of the previously expressed elements. The research carried out so far in the mixed forests on the basis of the production or average data values (diameter, volume, growth) can indicate the relevance of the mixed stands to raising the productivity, but it does not quantify the underlying factors. These elements can be a general research goal of future projects aimed at growth and yield in mixed stands. [ABSTRACT FROM AUTHOR]