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Ključne besede: non-native tree species, Alps, invasive alien species, forest management, urbanspace, climate changes
Objavljeno v DiRROS: 12.08.2022; Ogledov: 5; Prenosov: 0
Celotno besedilo (4,25 MB)

Povzetek: Timber harvesting constitutes extensive anthropogenic disturbance in temperate forests, producing a broad range of ecological impacts that most often enhance the demographic processes of vegetation. This study monitored post-harvest herb layer demography over a 6-year period in mesic Dinaric fir-beech forests (Slovenia), a vascular plant diversity hotspot among European forests. Three experimental harvesting intensities, i.e. full harvest (FH), partial harvest (PH) and a control treatment (NH), were each applied over a circular area of 4000 m2 and replicated three times at each of three study sites. Vegetation sampling was conducted before harvesting (in 2012), and two (2014) and six (2018) years following it, in a 400 m2 circular plot positioned in the centre of each treatment area. We focused on identifying general demographic patterns and evaluating the effects of various pre-disturbance abiotic and biotic predictors on compositional responses to disturbance. Two years after harvest (2012-2014), compositional shifts were larger than those in the next 4-year period (2014-2018), confirming the general theoretical prediction that species turnover rate decreases along a successional gradient. The degree of compositional shifts in gaps (FH) and thinned stands (PH) was affected by local abiotic factors (geomorphology of karst sinkholes) and community attributes, such as pre-harvest species richness. Our results indicate that compositional stability is positively associated with pre-disturbance species richness. Over the whole study period, increases in plot-level species richness (alpha diversity) and overall enrichment of the species pool (gamma diversity) were accompanied by compositional convergence, i.e. a decline in floristic dissimilarity (beta diversity) between and within study sites. However, the observed tendency towards homogenization was rather weak and would have been even more pronounced if the demographic type of persistent resident species had not shown a high degree of resistance, thus leaving a strong imprint on post-harvest vegetation development by preserving the forest characteristics of the herb layer community.
Ključne besede: forest succession, demographic types, community assembly, pre-disturbance factors, floristic convergence, fir-beech forests
Objavljeno v DiRROS: 22.07.2022; Ogledov: 38; Prenosov: 30
Celotno besedilo (1,91 MB)
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Povzetek: Riparian forests are among the most diverse terrestrial ecosystems, yet their biodiversity is increasingly threatened by habitat degradation, climate change, river regulation and invasive species. We investigated deadwood, widely recognized as an indicator for forest biodiversity, in riparian forests of the Mura-Drava-Danube Transboundary Biosphere Reserve. The Biosphere Reserve is a conservation area that spans five countries and three rivers located in south-eastern Europe. In detail, we analyzed the drivers of lying deadwood volume, occurrence and decay related to floodplain type, silvicultural management, and climatic conditions using regression models. Lying deadwood occurrence and volume significantly decreased as distance from the river edge increased, indicating that river dynamics likely play a role in deadwood accumulation in riparian forests. Deadwood volume was also positively influenced by stand basal area, a parameter that can be directly addressed by silvicultural management. Deadwood decay was affected positively by temperature and negatively by precipitation, highlighting the importance of climatic conditions on decay progression. However, in order to draw more accurate conclusions about the drivers and dynamics of deadwood in riparian forests, further monitoring efforts that consider river flooding and flow regime, deadwood transport and saproxylic organism activity in addition to forest management and site conditions, are needed.
Ključne besede: alluvial forest, hardwood floodplain, deadwood decay, Mura-Drava-Danube transboundary biosphere, reserve, riparian area, softwood floodplain, UNESCO biosphere reserve, wetlands
Objavljeno v DiRROS: 18.07.2022; Ogledov: 42; Prenosov: 36
Celotno besedilo (1,55 MB)
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Povzetek: Six broadleaf tree species (Celtis australis L. – Mediterranean hackberry, Quercus petraea (Matt.) Liebl. – sessile oak, Fagus sylvatica L. – European beech, Prunus avium L. – wild cherry, Juglans regia L. – Persian walnut and Acer pseudoplatanus L. – sycamore maple) were planted in 2012 in a trial in the Slovenian Karst on two sites differing in productivity to test their suitability for use in the conversion of old pine stands into ecologically more stable broadleaf forests and to investigate their possible response to the harsher growth conditions predicted in the future. The selected economically interesting tree species have higher timber quality than broadleaves which regenerate naturally (e.g., Ostrya carpinifolia, Fraxinus ornus, Quercus cerris). Measurements were taken in 2017, after four growth seasons. All planted species except Fagus sylvatica had a high survival rate. In total, 70% of all seedlings survived, which shows promising potential. The survival rate was higher at the site on flat terrain than at the site on a slope. Prunus avium was the most successful of all planted species in terms of survival rate, at 83%, and other measured parameters (height, height increment, stem diameter, vitality and quality), and Fagus sylvatica was the least successful, with a survival rate of only 20%. Celtis australis had the highest survival rate, at 87%. Acer pseudoplatanus had the largest differences in measured parameters between the more and less productive sites among all planted species. Quercus petraea showed high resistance to xeric conditions and is expected to be the most successful in conversions. All planted species except Fagus sylvatica show favourable initial potential for the future conversion of Karst pine forests.
Ključne besede: forest conversion, broadleaves, survival rate, seedlings quality, climate change
Objavljeno v DiRROS: 28.06.2022; Ogledov: 386; Prenosov: 165
Datoteka (3,13 MB)

Povzetek: European forest stands of small-diameter trees can provide industries with biomass as an alternative to fossil use. Small-tree harvesting is costly using conventional methods but using accumulating felling heads (AFH) in combination with a novel boom-corridor thinning (BCT) technique can increase harvester productivity and supply cost efficiency. This method has great potential to reduce costs, but its environmental impact compared with selective thinning (ST) needs to be determined. The objectives of this study were therefore to quantify and compare tree and soil damage as well as air, water and soil emissions for both BCT and ST in various European small-diameter-tree forests. Trials were performed in 84 study units (42 replications per thinning technique) across four countries. Damaged trees (with a diameter at breast height ≥ 7 cm) were measured after thinning and after forwarding. Harvesting emissions were calculated from a life cycle assessment. The percentage of remaining trees that had been damaged by the harvesting processes was 13% and 19% for BCT and ST, respectively, and the difference was significant. BCT exhibited the lowest emissions in all environmental impact categories considered, in all countries. Greenhouse gas emissions were on average 17% lower for BCT. BCT in small-diameter-tree stands therefore reduces the environmental impact of thinning operations compared with conventional methods, and results in less damage to the remaining trees.
Ključne besede: first thinning, harvesting damages, GHG emissions, forest biomass, forest operations
Objavljeno v DiRROS: 17.05.2022; Ogledov: 131; Prenosov: 107
Celotno besedilo (1,67 MB)
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