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Iskalni niz: "ključne besede" (vegetation) .

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Land surface phenology from satellite data : technical report
Urška Kanjir, Ana Potočnik Buhvald, Mitja Skudnik, Liza Stančič, Krištof Oštir, 2022, elaborat, predštudija, študija

Ključne besede: phenology, forest, remote sensing, MODIS, Sentinel-2, vegetation indices
Objavljeno v DiRROS: 29.12.2022; Ogledov: 353; Prenosov: 103
.pdf Celotno besedilo (4,52 MB)

The status and role of genetic diversity of trees for the conservation and management of riparian ecosystems : a European experts' perspective
Filip Alimpić, Jelena Milovanović, Remigiusz Pielech, Georgi Hinkov, Roland Jansson, Simon Dufour, Marcin Beza, Nebi Bilir, Luis Santos del Blanco, Gregor Božič, 2022, izvirni znanstveni članek

Povzetek: Riparian vegetation supports high biodiversity providing many services and is, therefore, an important landscape element. Riparian ecosystems are subject to numerous pressures leading to population decline and genetic erosion of riparian plants. This may have cascading effects at various ecosystem levels, including decreasing ecosystem services, so identifying the current status of genetic diversity of riparian tree species is vital to improve the effectiveness of restoration efforts. We aimed to elicit expert views on the status and importance of genetic diversity of tree species, and conservation needs across European riparian ecosystems. Sharing of such information among researchers, managers and policymakers has the potential to enhance ecological restoration and management of riparian ecosystems. We identified experts in riparian genetic resources conservation and management across Europe. These included stakeholders with different perspectives, ranging from researchers to practitioners. We designed a set of questionnaires where our identified experts were asked to answer questions related to the status and conservation of genetic diversity of riparian tree species in their respective countries. Specifically, we asked about societal awareness, legislative tools, good practices and conservation or restoration projects accounting for intraspecific genetic diversity and differentiation of tree species in riparian ecosystems. Questionnaire responses were analysed and discussed in light of the scientific literature to define needs and priorities related to the management and conservation of genetic diversity of riparian tree species. The experts recognized that a combination of in situ and ex situ measures and/or integrative conservation of riparian ecosystems is the most appropriate option for conserving the genetic diversity of riparian tree species. Simultaneous application of conservation measures at the level of priority species, identified by experts, and protection of riparian areas are required. Synthesis and applications. This study revealed the importance of recognizing the ecological processes that shape the genetic diversity of riparian tree species in hydrographic networks (dendritic spatial configuration, specific patterns of gene flow among riparian populations, fragmentation of river by dams) but also the need to overcome socio-economic barriers, such as lack of policy priority, deficiency in funding and weak legislation framework.
Ključne besede: biodiversity conservation, genetic erosion, genetic resources conservation, knowledge transfer, management, riparian genetic diversity, vegetation
Objavljeno v DiRROS: 08.12.2022; Ogledov: 327; Prenosov: 206
.pdf Celotno besedilo (1,02 MB)
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Variation in floristic and trait composition along environmental gradients in the herb layer of temperate forests in the transition zone between Central and SE Europe
Janez Kermavnar, Lado Kutnar, Aleksander Marinšek, 2022, izvirni znanstveni članek

Povzetek: Species- and trait-environment linkages in forest plant communities continue to be a frequent topic in ecological research. We studied the dependence of floristic and functional trait composition on environmental factors, namely local soil properties, overstory characteristics, climatic parameters and other abiotic and biotic variables. The study area comprised 50 monitoring plots across Slovenia, belonging to the EU ICP Forests monitoring network. Vegetation was surveyed in accordance with harmonized protocols, and environmental variables were either measured or estimated during vegetation sampling. Significant predictors of species composition were identified by canonical correspondence analysis. Correlations between plant traits, i.e. plant growth habit, life form, flowering features and CSR signature, were examined with fourth-corner analysis and linear regressions. Our results show that variation in floristic composition was mainly explained by climatic parameters (mean annual temperature, mean annual precipitation), soil properties (pH) and tree layer-dependent light conditions. Trait composition was most closely related with tree layer characteristics, such as shade-casting ability (SCA, a proxy for light availability in the understory layer), tree species richness and tree species composition. Amongst soil properties, total nitrogen content and soil texture (proportion of clay) were most frequently correlated with different species traits or trait states. The CSR signature of herb communities was associated with tree layer SCA, soil pH and mean annual temperature. The floristic composition of the studied herb-layer vegetation depended on temperature and precipitation, which are likely to be influenced by ongoing climate change (warming and drying). Trait composition exhibited significant links to tree layer characteristics and soil conditions, which are in turn directly modified by forest management interventions.
Ključne besede: vegetation–environment relationship, floristic composition, life-history traits, herbaceous species, Slovenia
Objavljeno v DiRROS: 15.04.2022; Ogledov: 515; Prenosov: 330
.pdf Celotno besedilo (2,43 MB)
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Carbon flux and environmental parameters data from an eddy covariance tower in a mid-succession ecosystem developed on abandoned karst grassland in Slovenia (2012-2019)
Koffi Dodji Noumonvi, Klemen Eler, Dominik Vodnik, Primož Simončič, Mitja Ferlan, 2021, zaključena znanstvena zbirka raziskovalnih podatkov

Povzetek: This data set was used to estimate carbon fluxes by comparing eddy covariance tower (Long = 13.916701, Lat = 45.543491) measurements with vegetation indices based estimates.
Ključne besede: eddy covariance, GPP, NEE, empirical model, LUE model, vegetation photosynthesis model, vegetation indices
Objavljeno v DiRROS: 21.02.2022; Ogledov: 609; Prenosov: 500
Celotno besedilo (29,63 KB)
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Empirical vs. light-use efficiency modelling for estimating carbon fluxes in a mid-succession ecosystem developed on abandoned karst grassland
Koffi Dodji Noumonvi, Mitja Ferlan, 2020, izvirni znanstveni članek

Povzetek: Karst systems represent an important carbon sink worldwide. However, several phenomena such as the CO2 degassing and the exchange of cave air return a considerable amount of CO2 to the atmosphere. It is therefore of paramount importance to understand the contribution of the ecosystem to the carbon budget of karst areas. In this study conducted in a mid-succession ecosystem developed on abandoned karst grassland, two types of model were assessed, estimating the gross primary production (GPP) or the net ecosystem exchange (NEE) based on seven years of eddy covariance data (2013%2019): (1) a quadratic vegetation index-based empirical model with five alternative vegetation indices as proxies of GPP and NEE, and (2) the vegetation photosynthesis model (VPM) which is a light use efficiency model to estimate only GPP. The Enhanced Vegetation Index (EVI) was the best proxy for NEE whereas SAVI performed very similarly to EVI in the case of GPP in the empirical model setting. The empirical model performed better than the VPM model which tended to underestimate GPP. Therefore, for this ecosystem, we suggest the use of the empirical model provided that the quadratic relationship observed persists. However, the VPM model would be a good alternative under a changing climate, as it is rooted in the understanding of the photosynthesis process, if the scalars it involves could be improved to better estimate GPP.
Ključne besede: eddy covariance, carbon flux, GPP, NEE, vegetation indices, remote sensing, satellite data, GPP map
Objavljeno v DiRROS: 03.01.2022; Ogledov: 558; Prenosov: 388
.pdf Celotno besedilo (3,07 MB)
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Empirical approach for modelling tree phenology in mixed forests using remote sensing
Koffi Dodji Noumonvi, Gal Oblišar, Ana Žust, Urša Vilhar, 2021, izvirni znanstveni članek

Povzetek: : Phenological events are good indicators of the effects of climate change, since phenological phases are sensitive to changes in environmental conditions. Although several national phenological networks monitor the phenology of different plant species, direct observations can only be conducted on individual trees, which cannot be easily extended over large and continuous areas. Remote sensing has often been applied to model phenology for large areas, focusing mostly on pure forests in which it is relatively easier to match vegetation indices with ground observations. In mixed forests, phenology modelling from remote sensing is often limited to land surface phenology, which consists of an overall phenology of all tree species present in a pixel. The potential of remote sensing for modelling the phenology of individual tree species in mixed forests remains underexplored. In this study, we applied the seasonal midpoint (SM) method with MODIS GPP to model the start of season (SOS) and the end of season (EOS) of six different tree species in Slovenian mixed forests. First, substitute locations were identified for each combination of observation station and plant species based on similar environmental conditions (aspect, slope, and altitude) and tree species of interest, and used to retrieve the remote sensing information used in the SM method after fitting the best of a Gaussian and two double logistic functions to each year of GPP time series. Then, the best thresholds were identified for SOS and EOS, and the results were validated using cross-validation. The results show clearly that the usual threshold of 0.5 is not best in most cases, especially for estimating the EOS. Despite the difficulty in modelling the phenology of different tree species in a mixed forest using remote sensing, it was possible to estimate SOS and EOS with moderate errors as low as <8 days (Fagus sylvatica and Tilia sp.) and <10 days (Fagus sylvatica and Populus tremula), respectively.
Ključne besede: phenology modelling, start of season, end of season, remote sensing, MODIS GPP, vegetation indices, threshold methods
Objavljeno v DiRROS: 23.08.2021; Ogledov: 790; Prenosov: 602
.pdf Celotno besedilo (2,63 MB)
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Patterns of understory community assembly and plant trait-environment relationships in temperate SE European forests
Janez Kermavnar, Lado Kutnar, 2020, izvirni znanstveni članek

Povzetek: 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.
Ključne besede: functional composition, functional diversity, ecological gradients, abiotic filtering, trait convergence, trait divergence, spatial scale, forest ground-layer vegetation, Slovenia
Objavljeno v DiRROS: 26.05.2020; Ogledov: 1705; Prenosov: 1167
.pdf Celotno besedilo (4,12 MB)
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Effects of disturbance on understory vegetation across Slovenian forest ecosystems
Lado Kutnar, Thomas Andrew Nagel, Janez Kermavnar, 2019, izvirni znanstveni članek

Povzetek: 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.
Ključne besede: vegetation dynamics, vascular-plant diversity, understory layer, disturbance, monitoring, temperate forests
Objavljeno v DiRROS: 27.11.2019; Ogledov: 2192; Prenosov: 1327
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Early responses of biodiversity indicators to various thinning treatments in mountain beech forests
Fabio Lombardi, Stefania Di Lella, Valeria Altieri, Simone Di Benedetto, Carmen Giancola, Bruno Lasserre, Lado Kutnar, Roberto Tognetti, Marco Marchetti, izvirni znanstveni članek

Povzetek: 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.
Ključne besede: deadwood, microhabitats, understory vegetation, mountain forests, sustainable forest management, Italian forests
Objavljeno v DiRROS: 04.10.2018; Ogledov: 2520; Prenosov: 1663
.pdf Celotno besedilo (835,42 KB)
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