The organic carbon stock (SOC) (t/ha) was calculated in different approaches in order to enhance the differences among methods and their utility regarding specific studies. Using data obtained in Romania (2000-2012) from 4,500 profiles and 9,523 soil horizons, the organic carbon stock was calculated for the main forest soils (18 types) using three different methods: 1) on pedogenetical horizons, by soil bulk density and depth class/horizon thickness; 2) by soil type and standard depths; 3) using regression equations between the quantity of organic C and harvesting depths. Even though the same data were used, the differences between the values of C stock obtained from the three methods were relatively high. The first method led to an overvaluation of the C stock. The differences between methods 1 and 2 were high (and reached 33% for andosol), while the differences between methods 2 and 3 were smaller (a maximum of 23% for rendzic leptosol). The differences between methods 2 and 3 were significantly lower especially for andosol, arenosol and vertisol. A thorough analysis of all three methods concluded that the best method to evaluate the organic C stock was to distribute the obtained values on the following standard depths: 0 - 10 cm; 10 - 20 cm; 20 - 40 cm; > 40 cm. For each soil type, a correlation between the quantity of organic C and the sample harvesting depth was also established. These correlations were significant for all types of soil; however, lower correlation coefficients were registered for rendzic leptosol, haplic podzol and fluvisol.

Abstract. Time studies represent important tools that are used in forest operations research to produce empirical models or to comparatively assess the performance of two or more operational alternatives with the general aim to predict the performance of operational behavior, choose the most adequate equipment or eliminate the useless time. There is a long tradition in collecting the needed data in a traditional fashion, but this approach has its limitations, and it is likely that in the future the use of professional software would be extended is such preoccupations as this kind of tools have been already implemented. However, little to no information is available in what concerns the performance of data analyzing tasks when using purpose-built professional time studying software in such research preoccupations, while the resources needed to conduct time studies, including here the time may be quite intensive. Our study aimed to model the relations between the variation of time needed to analyze the video-recorded time study data and the variation of some measured independent variables for a complex organization of a work cycle. The results of our study indicate that the number of work elements which were separated within a work cycle as well as the delay-free cycle time and the software functionalities that were used during data analysis, significantly affected the time expenditure needed to analyze the data (α=0.01, p<0.01). Under the conditions of this study, where the average duration of a work cycle was of about 48 seconds and the number of separated work elements was of about 14, the speed that was used to replay the video files significantly affected the mean time expenditure which averaged about 273 seconds for half of the real speed and about 192 seconds for an analyzing speed that equaled the real speed. We argue that different study designs as well as the parameters used within the software are likely to produce different results, a fact that should trigger other studies based on variations of these parameters. However, the results of this study give an initial overview on the time resources needed in processing and analyzing the data, and may help researchers in allocating their resources.

Abstract. The genetic diversity of Romanian most important coniferous tree species, the Norway spruce, was estimated by means of allozyme markers. A total of 695 adult trees sampled from eleven populations grouped in six mountainous areas in the Romanian Carpathians were analyzed. In three metapopulations (Maramureş, Postăvar and Parâng), to evaluate the influence of altitudinal gradient on genetic diversity, samples were collected from populations located at high and low altitude. At other location (Apuseni Mountains) we compared the narrow-crown biotype (Picea abies var. columnaris) and the pyramidal crown biotype (Picea abies var. pyramidalis) and explored the genetic structure of peat bog ecotype. By analyzing 7 enzyme systems and 12 enzyme coding loci, a total of 38 allelic variants have been detected. The mean value of polymorphic loci for the six sites was 86.1%, ranging between 83.3% and 91.7% and the mean expected heterozygosity was 0.115, resulting in a moderate level of genetic diversity. The highest genetic diversity (H e = 0.134) was found in the narrow-crown spruce population. Apuseni metapopulation showed the highest genetic diversity (H e = 0.125), being the most valuable for conservation of genetic resources. The small value of fixation index (F ST = 0.009) indicates a low genetic differentiation between the six sites and AMOVA test revealed a very high level of genetic diversity within population (99%). Comparative analysis of genetic parameters showed small differences between high and low altitude populations at each site, probably due to the neutral character of the markers analyzed and the effect of gene flow between gradiental populations.

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This study of the variation process of the chemical properties of eutric Cambisols on altitudinal levels, forest station subclasses and geomorphologic units, was based on soil analyses from 847 soil horizons gathered from 379 profiles. These profiles were distributed on Romania's entire forest area. The average values of the eutric Cambisol's chemical properties fit were within the known limits for this type of soil, but there were slight variations based on altitude, forest station subclass and geomorphologic units. As expected, the most chemical properties decrease according to the altitudinal levels, from altitudes of over 900 metres to altitudes of under 300 metres. At the level of the Ao horizon, the pH has a value of 5.78 (the soils are slightly acid) at altitudes lower than 300 m and of 5.03 (the soils are mildly acid) at altitudes higher than 900 m.The saturation degree basis is 72% (the soils are mezobasic towards eubasic) at altitudes lower than 300 m, and 56.7% (the soils are mezobasic towards oligomezobasic) at altitudes higher than 900 m. The exchangeable hydrogen decreases from 16.95 me/100 g soil at altitudes higher than 900 m to 9.01 me/100 g soil at altitudes lower than 300 m.