Silver fir (Abies alba Mill.) is one of the most valuable and productive tree species across European mountains, that accomplish multiple economic, protective and ecologic functions. Alongside spruce (Picea abies (L.) Karst) and beech (Fagus sylvatica L.), silver fir is a characteristic species for the Romanian Carpathians. Although silver fir tree is recommended for the diversification of forests in order to increase the resistance to climate change, it is very sensitive to climatic excesses, especially those that proceed rapidly. Therefore, the aim of this study is to investigate both the environmental conditions and stand characteristics of fir from five mountain ranges of the Romanian Carpathians. The study is based on data recorded over a period of 10 years (1990–2000). As such, a total of 77,251 stands that occupy 211,954 hectares have been investigated in regard to silver fir behaviour. MATLAB scripts were used for analysing consistent data volumes as well as the impact of eight factors on the silver fir productivity (altitude, field aspect, field slope, soil type, participation percentage, road distance, structure and consistency). Our analysis has revealed that higher silver fir productivity is found at altitudes of up to 1200 m, on mid and upper slopes, on NW field aspects, on eutric cambisols and dystric cambisols, with a 10–20% participation in stand composition and in relatively-even aged stands with a full consistency. This study offers valuable insights for forest managers that require comprehensive information in adopting effective strategies to enhance forest resilience under climate change.

The research aims to evaluate the impact of local industrial pollution on radial growth in affected Norway spruce (Picea abies (L.) Karst.) and silver fir (Abies alba Mill.) stands in the Tarnița study area in Suceava. For northeastern Romania, the Tarnița mining operation constituted a hotspot of industrial pollution. The primary processing of non-ferrous ores containing heavy metals in the form of complex sulfides was the main cause of pollution in the Tarnița region from 1968 to 1990. Air pollution of Tarnița induced substantial tree growth reduction from 1978 to 1990, causing a decline in tree health and vitality. Growth decline in stands located over 6 km from the pollution source was weaker or absent. Spruce trees were much less affected by the phenomenon of local pollution than fir trees. We analyzed the dynamics of resilience indices and average radial growth indices and found that the period in which the trees suffered the most from local pollution was between 1978 and 1984. Growth recovery of the intensively polluted stand was observed after the 1990s when the environmental condition improved because of a significant reduction in air pollution.

Forest soils belong to the major carbon sinks on Earth because of their high organic matter content. Forest soils from Europe store approximately 1.5 times more carbon than trees (EC/UN-ECE 2003). As dystric cambisol (2,292,385 ha) and eutric cambisol (869,909 ha) are the most widespread forest soils in Romania, we studied 5958 dystric cambisol pedogenetic horizons and 6784 eutric cambisol pedogenetic horizons. A series of correlations was made between soil organic matter and elevation, but also with tree age and stand production class. The differences between stratified soil organic matter in terms of slope aspect categories were tested, and multiple linear regression was used to determine the influences of some relief (elevation) and stand (age) characteristics on the soil organic matter content. Overall, the soil organic matter content increased with increasing elevation. Based on all 12,742 soil samples over a period of 33 years, the soil organic matter content is influenced by elevation and tree age, especially on shaded and partially shaded slope aspects.

This study analyses the possibility of assessing standing-tree wood density by microdrilling during tending forestry work carried out on Norway spruce stands. The research material comes from 4 experimental plots and consists of 270 trees (78 trees = control variant, 85 trees = moderate variant, and 107 trees = strong variant). The research objectives were to: (1) highlight wood density particularities, (2) identify wood resistance to microdrilling particularities, and (3) assess standing-tree wood density by microdrilling. For the control variant, average density recorded values of 0.357 ± 0.021 and 0.386 ± 0.027 g·cm⁻³; in the moderate variant, values were between 0.359 ± 0.029 and 0.393 ± 0.027 g·cm⁻³; and the strong variant was characterized by the limits of 0.364 ± 0.020 and 0.397 ± 0.027 g·cm⁻³. Average microdrilling resistance values were between 16.6 ± 2.6 and 22.5 ± 3.0% for the control variant; the moderate variant was characterized by the limits of 18.3 ± 3.1 and 23.4 ± 3.3%; and the strong variant recorded value of 19.7 ± 2.6 and 20.5 ± 2.6 (1.5)%. The linear regression results showed that microdrilling resistance increased as wood density increased. Additionally, generalized linear models showed that, when using covariates of microdrill resistance and tree diameter at breast height, there was a significant influence on the dependent variable, wood density, for all considered work variants. These results suggest that it is possible to consistently estimate both quality and resistance in Norway spruce standing trees using microdrilling. Our findings suggest that wood density and microdrilling resistance are dependent on biometric and qualitative characteristics, as well as the amount of tending forestry work conducted on Norway spruce stands.