11. Patterns of understory community assembly and plant trait-environment relationships in temperate SE European forestsJanez Kermavnar, Lado Kutnar, 2020, original scientific article Abstract: We analyzed variation in the functional composition and diversity of understory plant communities across different forest vegetation types in Slovenia. The study area comprises 10 representative forest sites covering broad gradients of environmental conditions (altitude, geology, light availability, soil type and reaction, nutrient availability, soil moisture), stand structural features and community attributes. The mean and variation of the trait values were quantified by community-weighted means and functional dispersion for four key plant functional traits: plant height, seed mass, specific leaf area and leaf dry matter content. At each study site, forest vegetation was surveyed at two different spatial scales (4 and 100 m2 ) in order to infer scale-dependent assembly rules. Patterns of community assembly were tested with a null model approach. We found that both trait means and diversity values responded to conspicuous gradients in environmental conditions and species composition across the studied forests. Our results mainly support the idea of abiotic filtering: more stressful environmental conditions (e.g., high altitude, low soil pH and low nutrient content) were occupied by communities of low functional diversity (trait convergence), which suggests a selective effect for species with traits adapted to such harsh conditions. However, trait convergence was also detected in some more resource-rich forest sites (e.g., low altitude, high soil productivity), most likely due to the presence of competitive understory species with high abundance domination. This could, at least to some extent, indicate the filtering effect of competitive interactions. Overall, we observed weak and inconsistent patterns regarding the impact of spatial scale, suggesting that similar assembly mechanisms are operating at both investigated spatial scales. Our findings contribute to the baseline understanding of the role of both abiotic and biotic constraints in forest community assembly, as evidenced by the non-random patterns in the functional structure of distinct temperate forest understories.
Keywords: functional composition, functional diversity, ecological gradients, abiotic filtering, trait convergence, trait divergence, spatial scale, forest ground-layer vegetation, Slovenia
Published in DiRROS: 26.05.2020; Views: 1905; Downloads: 1269
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12. Effects of disturbance on understory vegetation across Slovenian forest ecosystemsLado Kutnar, Thomas Andrew Nagel, Janez Kermavnar, 2019, original scientific article Abstract: The herbaceous understory represents a key component of forest biodiversity across temperate forests of Europe. Here, we quantified changes in the diversity and composition of the forest understory layer in representative Slovenian forest ecosystems between 2004/05 and 2014/15. In total, 60 plots were placed across 10 different managed forest types, ranging from lowland deciduous and mid-altitude mesic mixed forests to mountain conifer forests. This network is part of an international network of sites launched within the ICP Forests Programme aimed to assess the condition of forests in Europe. To examine how disturbance influenced understory dynamics, we estimated the disturbance impacts considering both natural and/or anthropogenic disturbances that cause significant damage to trees and to ground-surface layers, including ground-vegetation layers and upper-soil layers. Species richness across 10 sites (gamma diversity) significantly decreased from 272 to 243 species during the study period, while mean species richness per site did not significantly change. The mean value of site level Shannon diversity indices and evenness significantly increased. The cover of most common plant species increased during the monitoring period. The mean value of disturbance estimates per site increased from 0.8% in 2004/05 (ranging from 0% to 2.5%) to 16.3% in 2014/15 (ranging from 5.0% to 38.8%), which corresponded to a reduction in total vegetation cover, including tree-layer cover. More disturbed sites showed larger temporal changes in species composition compared to less disturbed sites, suggesting that forest disturbances caused understory compositional shifts during the study period. Rather than observing an increase in plant diversity due to disturbance, our results suggest a short-term decrease in species number, likely driven by replacement of more specialized species with common species.
Keywords: vegetation dynamics, vascular-plant diversity, understory layer, disturbance, monitoring, temperate forests
Published in DiRROS: 27.11.2019; Views: 2351; Downloads: 1434
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13. Estimation of carbon fluxes from Eddy covariance data and satellite-derived vegetation indices in a Karst grassland (Podgorski Kras, Slovenia)Koffi Dodji Noumonvi, Mitja Ferlan, Klemen Eler, Giorgio Alberti, Alessandro Peressotti, Sofia Cerasoli, 2019, original scientific article Keywords: eddy covariance, carbon flux, GPP, NEE, vegetation indices, remote sensing, satellite data, GPP map
Published in DiRROS: 10.04.2019; Views: 2534; Downloads: 1531
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14. Early responses of biodiversity indicators to various thinning treatments in mountain beech forestsFabio Lombardi, Stefania Di Lella, Valeria Altieri, Simone Di Benedetto, Carmen Giancola, Bruno Lasserre, Lado Kutnar, Roberto Tognetti, Marco Marchetti, original scientific article Abstract: In recent decades, the conservation of biodiversity has become one of the main areas under consideration in managing forests in an ecologically sustainable way. Forest management practices are primary drivers of diversity and may enhance or decrease forest biodiversity, according to the measures applied (thinning options). We have focused on three beech (Fagus sylvatica L.) forests across a latitudinal gradient in Italy, characterised by different structures resulting from dissimilar management. We tested the short-term effects of differently-based silvicultural intervention vs. stands where no silvicultural practices were applied on biodiversity indicators and related proxies: deadwood amounts, microhabitat density, floristic richness and life form abundance. In each study area, the occurrence of the above indicators and proxies was evaluated before and after the implementation of crop tree thinning (CTT) and thinning from below (LT) methods, comparing them with control areas where no interventions were performed. After two years, the management options resulted in different responses of the investigated parameters. The CTT increased deadwood amounts in comparison with the LT ones, while stumps increased significantly after the LT thinning. Microhabitats increased significantly where intervention was not undertaken. On the contrary, they remained unaltered after the LT treatments. CTT thinning created favourable conditions for the development of microhabitats and their proliferation in the long term. Two years after the application of the CTT thinning treatment, all forest stands demonstrated a significant increase in their floristic richness and herb layer cover. Significant differences were also found in both the frequency and cover of life forms in relation to silvicultural treatment. These findings provide a better understanding of short-term effects of silvicultural treatment useful for maintaining biodiversity in mountain beech forests.
Keywords: deadwood, microhabitats, understory vegetation, mountain forests, sustainable forest management, Italian forests
Published in DiRROS: 04.10.2018; Views: 2667; Downloads: 1743
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15. Occurrence of invasive alien plant species in the floodplain forests along the Mura River in SloveniaAleksander Marinšek, Lado Kutnar, original scientific article Abstract: Background and purpose: The objectives of our study were to identify invasive alien plant species (IAS) in the main Natura 2000 forest habitat types (FHT) along the Mura River in Slovenia, and to estimate their abundance and cover. The aim of our study was to find out a) Which IAS appear in the research forests? b) What is their frequency and cover percentage? c) Whether individual IAS prosper better in some FHT than others? d) What is the correlation between the cover of IAS and the tree layer cover? Materials and methods: We analysed the fidelity of invasive plant species to individual FHT. The studied FHTs along the Mura River were the following: 91E0* (Alluvial forests with Alnus glutinosa and Fraxinus excelsior), 91F0 (Riparian mixed forests of Quercus robur, Ulmus laevis and Ulmus minor, Fraxinus excelsior or Fraxinus angustifolia, along the great rivers) and 91L0 (Illyrian oak-hornbeam forests). Two forest areas of about 600 ha were studied in total. With the intention to calculate number and cover of IAS some statistical analysis was made. In addition, correlations between the abundances of the most present IAS and cover of upper tree layer were carried out. Results: In total, 15 IAS were recorded in studied FHTs. Some species, like Robinia pseudoacacia, Impatiens glandulifera, I. parviflora, Fallopia japonica (incl. F. x bohemica), Erigeron annuus, Ambrosia artemisiifolia, Amorpha fruticosa, Conyza canadensis and Juncus tenuis occur only in one or two FHTs, while some species can be found in all studied FHTs (e.g. Solidago sp.). We found out that the most threatened forests are those with prevailing Salix alba, Alnus glutinosa, Fraxinus angustifolia and Ulmus laevis tree species. Those are the forests of FHT 91E0 which have less dense tree canopies, grow closest to the river and on the wettest sites. We found a statistically significant higher number and cover of IAS in the FHT 91E0 and the lowest number and cover in FHT 91L0. Conclusions: Alluvial forests with Alnus glutinosa and Fraxinus excelsior (FHT 91E0) along the Mura River are most prone to invasion of IAS. The increasing presence of IAS in the study areas seriously affects natural regeneration, stability, and continuity of floodplain forests in all other FHTs in the study area. At the same time the amount of IAS in these forests also depends on management measures and their intensities which accelerate light availability. Some measures and guidelines for managing of these forests with the purpose of reducing IAS impacts are suggested in this study.
Keywords: non-native plants, riparian vegetation, habitat types, conservation management, forest management
Published in DiRROS: 16.04.2018; Views: 2872; Downloads: 1517
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16. Plant diversity of selected Quercus robur L. and Quercus petraea (Matt.) Liebl. forests in SloveniaLado Kutnar, 2006, original scientific article Abstract: In Slovenia, the plant species diversity on 225 research plots dominated by pedunculate oak (Quercus robur L.) and by sessile oak (Quercus petraea (Matt.) Liebl.) has been analysed. Plots of Q. robur are located in five, andplots of Q. petraea in four semi-natural managed forest complexes. In the tree layer, 28 species were found beside the dominant two oak species, with Carpinus betulus L., Picea abies (L.) Karst., Quercus cerris L. and Fagus sylvatica L. having significant shares of growing stock. Based on the understorey vegetation (shrub and herb layer, terricolous mosses), the Ddetrended Correspondence Analysis (DdCA) made a clear distinction between plots with dominant Q. robur and those with Q. petraea. The understorey vegetation also proved to be a valuable indicator of the site conditions and of forest management in the past. Based on ordination, lowland pedunculate oak forests of relatively long standing near to natural management have been separated from the pedunculate oak forests where spruce was favoured by the forest management, and from the man-made pedunculate oak stands on primary sites of Q. petraea. DCA clearly differentiated the sessile oak forests in warmer climate of Sub-Mediterranean region, and in warmer meso-sites of Pre-Pannonian region from other sessile oak forests. The main gradients of vegetation structure and of species diversity, as well main ecological gradients in different oak forests were obtained by ordination technique.
Keywords: floristic composition, vegetation structure, biodiversity, growing stock
Published in DiRROS: 12.07.2017; Views: 4193; Downloads: 1786
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17. Silver fir (Abies alba Mill.) distribution in Slovenian forestsAndrej Ficko, Andrej Bončina, 2006, original scientific article Abstract: We analysed the characteristics of silver fir (Abies alba Mill.) occurrence and distribution in Slovenia using databases of the Slovenian Forest Service (SFS). Silver fir is the third most widely distributed tree species in Slovenia, occurring in approximately 40 % of total forest area, but abundantly in less than 10 %. Its share in total growing stock varies between separate forest management regions. It is more abundant in the Dinaric and part of the Pre-alpine phytogeographic regions. The highest share in total growing stock reaches at altitudes between 800 m and 1000 m above sea level, forests with silver fir cover the most extensive surface in the altitude belt from 1000 to 1200 m. Silver fir occurs abundantly in 11 syntaxes. Between them, silver fir-beech forests (Abieti-Fagetum dinaricum TREG. 57, syn.: Omphalodo-Fagetum (TREG.57 corr. PUNC.80) MAR et al. 93) strongly prevail, followed by fir forests with fern (Dryopterido-Abietetum KOŠ.65, syn.: Galio rotundifolii-Abietetum BARTSCH.40). Silver fir diameter distribution considerably varies between separate forest management regions. The regions with the highest share of silver fir (Postojna, Kočevje) dominate also in having large diameter silver fir trees, whereas in other regions (e.g. Nazarje, Kranj, Maribor) small diameter silver fir trees are prevalent. Ddevelopmental stage structure shows that in forest stands with silver fir there is a higher share of timber phase, stands in regeneration, youth stands and selective forests. Considering regeneration we can conclude, that more intensive decreasing trend in silver fir share is expected in the Ddinaric phytogeographic region than in northern parts of Slovenia. Successful regeneration due to lower red deer population and balanced stem diameter structure with higher proportion of small diameter trees promise easier conservation of silver fir in northern parts.
Keywords: forest stand structure, forest vegetation, altitude, Slovenia
Published in DiRROS: 12.07.2017; Views: 4369; Downloads: 1744
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