1. Congruence between vascular plants and bryophytes in response to ecological conditions in sustainably managed temperate forests (taxonomic- and trait-based levels)Lado Kutnar, Janez Kermavnar, Marko S. Sabovljević, 2023, original scientific article Abstract: Vascular plant species (VP) and bryophytes (B) constitute a significant portion of forest biodiversity and respond to both management intensity and natural disturbances within forests. In this study, we investigated the cross-taxa congruence between understorey VP and B at both diversity and composition levels across a wide range of sustainably managed forests in Slovenia. The taxonomic and functional characteristics of the selected plant groups were studied, with a particular emphasis on ground-dwelling species. We employed a trait-based approach to examine the functional characteristics. On average, the species richness of B in sustainably managed temperate forests increased with the corresponding number of VP. Furthermore, a moderate positive correlation in species composition between the studied groups of ground-dwelling organisms was also observed. The ground-dwelling VP and B were congruent in terms of trait-based composition, which was influenced by soil reaction and nutrients and light availability, while trait-based diversity was only slightly similar in response to moisture. A negative correlation between the composition of stress-tolerant VP and B hemeroby was found, indicating forest environments with a low level of disturbance. This is likely due to the sustainable management of Slovenian forests, where climate change and natural disturbances have intensified in recent years. A cross-taxon comparison of the two groups at four different levels, namely taxonomic-based diversity and composition and trait-based diversity and composition, revealed varying degrees of congruence. It is therefore important to monitor the status and temporal trends of both groups from different aspects to draw reliable conclusions.
Keywords: understory, mosses, terricolous species, diversity, composition, taxonomy, life-history traits, environmental gradients, managed forest, ICP Forests program, Slovenia
Published in DiRROS: 10.10.2023; Views: 510; Downloads: 184
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2. Are ecological niche optimum and width of forest plant species related to their functional traits?Janez Kermavnar, Lado Kutnar, Aleksander Marinšek, Valerija Babij, 2023, original scientific article Abstract: The ecological niche is one of the central concepts in plant ecology. Understanding which biological traits influence plant niches remains limited, preventing large-scale generalizations. Using a representative pool of 94 herb-layer species frequently occurring in the Slovenian forest vegetation types and an extensive suite of 28 plant functional traits, we tested whether traits serve as predictors for the optimum and width of plant species ecological niche. Niche optimum (mean) and niche width (standard deviation) of each species were derived from community-level ecological indicator values for six environmental gradients, i.e., light, temperature, continentality, moisture, soil reaction and nutrients. We investigated relationships between niche parameters and functional traits through a random forest analysis to account for relatively high trait correlations. Our results suggest that niche optimum and width of forest plant species are related to their functional traits. The two niche parameters were best explained by similar set of traits; however, the relative importance of traits differed substantially. Traits associated with disturbances (frequency and severity), plant dispersal (seed mass, dispersal syndrome), leaf economics spectrum (specific leaf area) and life strategy (CSR scores) showed the highest overall significance in predicting niche optimum and width. Functional traits were, on average, better predictors for niche optimum (average variance explained across all six environmental factors: 20.2%) than for niche width (average variance explained: 7.7%). Intraspecific trait variability, not considered in this study, likely plays an important role in case of niche width. The analyses suggest that, while not all traits impact niche parameters to the same degree, it is crucial to consider traits representing different ecological dimensions and revealing leading patterns of trait coordination. We recommend that the relative importance of traits for species niche parameters should be tested on a larger spatial scale using broader pool of forest understory plants across Europe.
Keywords: ecological gradients, Ellenberg indicator values, Slovenian forest types, trait-environment relationship, understory plants
Published in DiRROS: 09.03.2023; Views: 498; Downloads: 284
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3. 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: 2374; Downloads: 1442
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4. 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: 2698; Downloads: 1754
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