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2. Evaluation of height changes in uneven-aged spruce–fir–beech forest with freely available nationwide lidar and aerial photogrammetry dataAnže Martin Pintar, Mitja Skudnik, 2025, izvirni znanstveni članek Povzetek: Tree height and vertical forest structure are important attributes in forestry, but their traditional measurement or assessment in the field is expensive, time-consuming, and often inaccurate. One of the main advantages of using remote sensing data to estimate vertical forest structure is the ability to obtain accurate data for larger areas in a more time- and cost-efficient manner. Temporal changes are also important for estimating and analysing tree heights, and in many countries, national airborne laser scanning (ALS) surveys have been conducted either only once or at specific, longer intervals, whereas aerial surveys are more often arranged in cycles with shorter intervals. In this study, we reviewed all freely available national airborne remote sensing data describing three-dimensional forest structures in Slovenia and compared them with traditional field measurements in an area dominated by uneven-aged forests. The comparison of ALS and digital aerial photogrammetry (DAP) data revealed that freely available national ALS data provide better estimates of dominant forest heights, vertical structural diversity, and their changes compared to cyclic DAP data, but they are still useful due to their temporally dense data. Up-to-date data are very important for forest management and the study of forest resilience and resistance to disturbance. Based on field measurements (2013 and 2023) and all remote sensing data, dominant and maximum heights are statistically significantly higher in uneven-aged forests than in mature, even-aged forests. Canopy height diversity (CHD) information, derived from lidar ALS and DAP data, has also proven to be suitable for distinguishing between even-aged and uneven-aged forests. The CHDALS 2023 was 1.64, and the CHDCAS 2022 was 1.38 in uneven-aged stands, which were statistically significantly higher than in even-aged forest stands.
Ključne besede: uneven-aged forest, freely available national airborne remote sensing data, lidar, aerial photography, dominant height, canopy height diversity, periodic annual increment
Objavljeno v DiRROS: 09.01.2025; Ogledov: 257; Prenosov: 162
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3. High-resolution Pan-European forest structure maps : an integration of earth observation and national forest inventory dataJukka Miettinen, Patricia Adame, Radim Adolt, Iciar Alberdi, Oleg Antropov, Ólafur Arnarsson, Rasmus Astrup, Ambros Berger, Jón Bogason, Gherardo Chirici, Luka Krajnc, Mitja Skudnik, 2024, zaključena znanstvena zbirka raziskovalnih podatkov Ključne besede: uneven-aged forest, lidar data, canopy height model, voxels, canopy height diversity
Objavljeno v DiRROS: 13.08.2024; Ogledov: 734; Prenosov: 875
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4. Identifying even- and uneven-aged forest stands using low-resolution nationwide lidar dataAnže Martin Pintar, Mitja Skudnik, 2024, izvirni znanstveni članek Povzetek: In uneven-aged forests, trees of different diameters, heights, and ages are located in a small area, which is due to the felling of individual trees or groups of trees, as well as small-scale natural disturbances. In this article, we present an objective method for classifying forest stands into even- and uneven-aged stands based on freely available low-resolution (with an average recording density of 5 points/m2) national lidar data. The canopy closure, dominant height, and canopy height diversity from the canopy height model and the voxels derived from lidar data were used to classify the forest stands. Both approaches for determining forest structural diversity (canopy height diversity—CHDCHM and CHDV) yielded similar results, namely two clusters of even- and uneven-aged stands, although the differences in vertical diversity between even- and uneven-aged stands were greater when using CHM. The first analysis, using CHM for the CHD assessment, estimated the uneven-aged forest area as 49.3%, whereas the second analysis using voxels estimated it as 34.3%. We concluded that in areas with low laser scanner density, CHM analysis is a more appropriate method for assessing forest stand height heterogeneity. The advantage of detecting uneven-aged structures with voxels is that we were able to detect shade-tolerant species of varying age classes beneath a dense canopy of mature, dominant trees. The CHDCHM values were estimated to be 1.83 and 1.86 for uneven-aged forests, whereas they were 1.57 and 1.58 for mature even-aged forests. The CHDV values were estimated as 1.50 and 1.62 for uneven-aged forests, while they were 1.33 and 1.48 for mature even-aged forests. The classification of stands based on lidar data was validated with data from measurements on permanent sample plots. Statistically significantly lower average values of the homogeneity index and higher values of the Shannon–Wiener index from field measurements confirm the success of the classification of stands based on lidar data as uneven-aged forests.
Ključne besede: uneven-aged forest, lidar data, canopy height model, voxels, canopy height diversity
Objavljeno v DiRROS: 13.08.2024; Ogledov: 499; Prenosov: 810
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5. Revealing subtle active tectonic deformation: integrating lidar, photogrammetry, field mapping, and geophysical surveys to assess the Late Quaternary activity of the Sava Fault (Southern Alps, Slovenia)Petra Jamšek Rupnik, Jure Atanackov, Barbara Horn, Branko Mušič, Marjana Zajc, Christoph Grützner, Kamil Ustaszewski, Sumiko Tsukamoto, Matevž Novak, Blaž Milanič, Anže Markelj, Kristina Ivančič, Ana Novak, Jernej Jež, Manja Žebre, Miloš Bavec, Marko Vrabec, 2024, izvirni znanstveni članek Povzetek: We applied an interdisciplinary approach to analyze the late Quaternary activity of the Sava Fault in the Slovenian Southern Alps. The Sava Fault is an active strike-slip fault, and part of the Periadriatic Fault System that accommodated the convergence of Adria and Europe. It is one of the longest faults in the Southern Alps. Using high-resolution digital elevation models from lidar and photogrammetric surveys, we were able to overcome the challenges of assessing fault activity in a region with intense surface processes, dense vegetation, and relatively low fault slip rates. By integrating remote sensing analysis, geomorphological mapping, structural geological investigations, and near-surface geophysics (electrical resistivity tomography and ground penetrating radar), we were able to find subtle geomorphological indicators, detect near-surface deformation, and show distributed surface deformation and a complex fault pattern. Using optically stimulated luminescence dating, we tentatively estimated a slip rate of 1.8 ± 0.4 mm/a for the last 27 ka, which exceeds previous estimates and suggests temporal variability in fault behavior. Our study highlights the importance of modern high-resolution remote sensing techniques and interdisciplinary approaches in detecting tectonic deformation in relatively low-strain rate environments with intense surface processes. We show that slip rates can vary significantly depending on the studied time window. This is a critical piece of information since slip rates are a key input parameter for seismic hazard studies.
Ključne besede: active fault, lidar, photogrammetry, tectonic geomorphology, structural geology, geophysics, electrical resistivity tomography, ground penetrating radar, slip rate, Sava Fault
Objavljeno v DiRROS: 30.04.2024; Ogledov: 916; Prenosov: 347
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6. Assessing the heterogeneity and conservation status of the Natura 2000 priority forest habitat type Tilio–Acerion (9180*) based on field mappingJanez Kermavnar, Erika Kozamernik, Lado Kutnar, 2023, izvirni znanstveni članek Povzetek: Priority habitat types (HTs) within the Natura 2000 network are of the highest importance for conservation in Europe. However, they often occur in smaller areas and their conservation status is not well understood. One such HT is that of the Tilio–Acerion forests of slopes, screes and ravines (9180*). The Natura 2000 study site, Boč–Haloze–Donačka gora, in the Sub-Pannonian region of eastern Slovenia is characterized by a matrix of European beech forests and includes rather small, fragmented areas covered by Tilio–Acerion forests. The goal of this research was to examine the heterogeneity and conservation status of the selected HT through field mapping, which was performed in the summer of 2020. As the conservation of HT calls for a more detailed approach, we distinguished between the following four pre-defined habitat subtypes: (i) Acer pseudoplatanus-Ulmus glabra stands growing mostly in concave terrain, (ii) Fraxinus excelsior stands growing on slopes, (iii) Tilia sp. stands with thermophilous broadleaves occurring on ridges and slopes, (iv) Acer pseudoplatanus stands occurring on more acidic soils with an admixture of Castanea sativa. Field mapping information was complemented with the assessment of habitat subtype characteristics using remote sensing data. The results showed that habitat subtypes differed significantly in terms of area, tree species composition, forest stand characteristics, relief features and the various threats they experienced (e.g., fragmentation, tree mortality, ungulate browsing pressure). The differences between subtypes were also evident for LiDAR-derived environmental factors related to topography (i.e., terrain steepness and Topographic Position Index). This study provides a baseline for setting more realistic objectives for the conservation management of priority forest HTs. Due to the specificities of each individual habitat subtype, conservation activities should be targeted to the Natura 2000 habitat subtype level.
Ključne besede: forest habitat subtype, monitoring, biodiversity conservation, LiDAR, Slovenia, NATURA 2000
Objavljeno v DiRROS: 03.02.2023; Ogledov: 1563; Prenosov: 571
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7. Retrieval of vertical mass concentration distributionsLonglong Wang, Samo Stanič, Klemen Bergant, William Eichinger, Griša Močnik, Luka Drinovec, Janja Vaupotič, Miloš Miler, Mateja Gosar, Asta Gregorič, 2019, izvirni znanstveni članek Povzetek: Aerosol vertical profiles are valuable inputs for the evaluation of aerosol transport models, in order to improve the understanding of aerosol pollution ventilation processes which drive the dispersion of pollutants in mountainous regions. With the aim of providing high-accuracy vertical distributions of particle mass concentration for the study of aerosol dispersion in small-scale valleys, vertical profiles of aerosol mass concentration for aerosols from different sources (including Saharan dust and local biomass burning events) were investigated over the Vipava valley, Slovenia, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. The analysis was based on datasets taken between 1–30 April 2016. In-situ measurements of aerosol size, absorption, and mass concentration were combined with lidar remote sensing, where vertical profiles of aerosol concentration were retrieved. Aerosol samples were characterized by SEM-EDX, to obtain aerosol morphology and chemical composition. Two cases with expected dominant presence of different specific aerosol types (mineral dust and biomass-burning aerosols) show significantly different aerosol properties and distributions within the valley. In the mineral dust case, we observed a decrease of the elevated aerosol layer height and subsequent spreading of mineral dust within the valley, while in the biomass-burning case we observed the lifting of aerosols above the planetary boundary layer (PBL). All uncertainties of size and assumed optical properties, combined, amount to the total uncertainty of aerosol mass concentrations below 30% within the valley. We have also identified the most indicative in-situ parameters for identification of aerosol type.
Ključne besede: valley air pollution, aerosol vertical distributions, lidar remote sensing, in-situ measurements, aerosol identification
Objavljeno v DiRROS: 03.03.2022; Ogledov: 1530; Prenosov: 563
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8. Ocena zgradbe in stabilnosti gozdnega roba kot pripomoček za ovrednotenje klimatske in zaščitne funkcije primestnih gozdovDavid Hladnik, Andrej Kobler, Janez Pirnat, 2020, izvirni znanstveni članek Povzetek: V prispevku podajamo razširjen povzetek iz članka, objavljenega v reviji Forests z naslovom Evaluation of forest edge structure and stability in peri-urban forests (Hladnik in sod., 2020). Dodali smo predloge o prenovi varovalne, zaščitne in klimatske funkcije gozdov ter predloge ukrepov, ki izhajajo iz izsledkov raziskave gozdnih robov. Analizirali smo vertikalno zgradbo gozdnih robov in opozorili na pomen dimenzijskega razmerja dreves h/d na gozdnih robovih primestnih gozdnih zaplat ob Ljubljani, kjer ob pozidanih zemljiščih prevladujejo visoki in strmi gozdni robovi. Predstavili smo preprosto metodologijo, na podlagi katere je mogoče z metodami daljinskega zbiranja podatkov zasnovati monitoring primestnih gozdnih površin in gozdnih robov.
Ključne besede: funkcije gozdov, stabilnost gozdnega roba, gozdni rob, zgradba gozdnega roba, LiDAR, urbani gozdovi
Objavljeno v DiRROS: 09.06.2020; Ogledov: 2960; Prenosov: 936
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9. Evaluation of forest edge structure and stability in peri-urban forestsDavid Hladnik, Andrej Kobler, Janez Pirnat, 2020, izvirni znanstveni članek Povzetek: In the presented research, we studied the forest edge structure of urban and peri-urban forests on the outskirts of Ljubljana (Slovenia) consisting of a number of patches covering the collective surface of 1884 ha. They differ from each other according to the degree of fragmentation and by the share of the interior forest area. On the basis of LiDAR data, we conducted an analysis of the edges of the persistent forest patches and estimated them with regard to the land use they bordered on. The horizontal estimation of forest edges and the changes of forest edges, in the last decades, were estimated using digital orthophoto images of cyclic aerial surveys of Slovenia, from 1975 to 2018. The data, provided by LiDAR, were used to obtain an accurate estimate of forest edges and the metrics of their vertical canopy structure. On the basis of the canopy height model (CHM), we determined the height classes, the heights of the tallest trees, and indices of canopy height diversity (CHD) as variables subjected to a k-means cluster analysis. To determine the forest edge and trees stability, their heights and diameters at breast height (DBH) were measured and their canopy length and h/d (height/diameter) dimension ratios were estimated. In the study area of the Golovec forest patch, more than half of the forest edge segments (56%) border on residential buildings. After the construction of buildings, 54% of the newly formed forest edges developed a high and steep structure. Unfavorable h/d dimension ratio was estimated for 16% of trees, more among the coniferous than among the deciduous trees. Similar characteristics of newly formed forest edges bordering on built-up areas were determined in other sub-urban forest patches, despite the smaller share of such forest edges (19% and 10%, respectively). Tools and methods presented in the research enable the implementation of concrete silvicultural practices in a realistic time period and extend to ensure that adequate forestry measures are taken to minimize possible disturbances.
Ključne besede: forest ecosystem services, forest edge stability, forest edge structure, LiDAR, urban forests
Objavljeno v DiRROS: 26.05.2020; Ogledov: 2533; Prenosov: 1462
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10. Predlog prostorske razporeditve izbranih primestnih gozdov na podlagi daljinsko pridobljenih podatkov in terenske kontroleDavid Hladnik, Sebastian Bambič, Aleš Benčina, Jan Mihelič, Žiga Repotočnik, Janez Pirnat, 2019, strokovni članek Povzetek: V pričujočem prispevku predstavljamo predlog opredelitve t.i. primestnih gozdov na podlagi študije, ki sta jo predstavila Pirnat in Hladnik (2018), v kateri sta analizirala zgradbo krajine in povezljivost gozdov v mestnem in obrobnem območju 30 največjih slovenskih mest. Članek je služil kot osnova za delo s študenti pri dveh izbirnih predmetih Gozdovi, ljudje in trajnostne krajine in Prostorski monitoring naravnega okolja na magistrskem študijskem programu druge stopnje Gozdarstvo in upravljanje gozdnih ekosistemov. Študentje so v okviru seminarjev na podlagi predstavljene metodologije članka (Pirnat in Hladnik, 2018), zbirke podatkov o državnih cestah, podatkovne zbirke CORINE Land Cover, podatkov o gozdnih sestojih, podrobnega digitalnega modela reliefa ter na podlagi terenskih ogledov v programskem okolju ArcMap izdelali predlagane spremembe površin t. i. primestnih gozdov štirih izbranih mest (Grosuplje, Kočevje, Ljubljana, Slovenj Gradec). To delo je primerna osnova za izdelavo metodologije določanja primestnih gozdov, če se bo pokazala potreba.
Ključne besede: primestni gozdovi, krajinska ekologija, daljinsko zaznavanje, Lidar
Objavljeno v DiRROS: 23.04.2019; Ogledov: 3705; Prenosov: 1042
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