21. Artificial neural networks as an alternative method to nonlinear mixed-effects models for tree height predictionsMitja Skudnik, Jernej Jevšenak, 2022, izvirni znanstveni članek Povzetek: Tree heights are one of the most important aspects of forest mensuration, but data are often unavailable due to costly and time-consuming field measurements. Therefore, various types of models have been developed for the imputation of tree heights for unmeasured trees, with mixed-effects models being one of the most commonly applied approaches. The disadvantage here is the need of sufficient sample size per tree species for each plot, which is often not met, especially in mixed forests. To avoid this limitation, we used principal component analysis (PCA) for the grouping of similar plots based on the most relevant site descriptors. Next, we compared mixed-effects models with height-diameter models based on artificial neural networks (ANN). In terms of root mean square error (RMSE), mixed-effects models provided the most accurate tree height predictions at the plot level, especially for tree species with a smaller number of tree height measurements. When plots were grouped using the PCA and the number of observations per category increased, ANN predictions improved and became more accurate than those provided by mixed-effects models. The performance of ANN also increased when the competition index was included as an additional explanatory variable. Our results show that in the pursuit of the most accurate modelling approach for tree height predictions, ANN should be seriously considered, especially when the number of tree measurements and their distribution is sufficient. Ključne besede: height-diameter models, national forest inventory, permanent sample plot, mixed forests, model comparison, principal component analysis Objavljeno v DiRROS: 08.06.2022; Ogledov: 495; Prenosov: 206 Povezava na datoteko |
22. Nacionalna gozdna inventura : interna navodila za terensko delo (2020-2024) : (ver. 02 / 2022) : dopolnitve 13. 5. 2022Mitja Skudnik, Jure Žlogar, Aleš Poljanec, Rok Pisek, Anže Martin Pintar, Gal Kušar, Matjaž Guček, Andrej Grah, Marko Kovač, 2020, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: nacionalna gozdna inventura, monitoring, terenske meritve, trajne vzorčne ploskve, navodila Objavljeno v DiRROS: 07.06.2022; Ogledov: 816; Prenosov: 335 Celotno besedilo (4,71 MB) |
23. Določitev ploskev tretjega panela Nacionalne gozdne inventure za terenski popis gozd/druga gozdna zemljišča/negozd : predstavljeno na spletnem seminarju in delavnici Nacionalna Gozdna Inventura 2022 in Sklad za podnebne spremembe, 11. - 15. 4. 2022Anže Martin Pintar, Andrej Grah, Mitja Skudnik, 2022, prispevek na konferenci brez natisa Ključne besede: gozdovi, gozdarstvo, raba zemljišč, Nacionalna gozdna inventura, definicija gozda, negozd, druge gozdne površine Objavljeno v DiRROS: 12.04.2022; Ogledov: 717; Prenosov: 0 |
24. Stanje slovenskih gozdov : poročilo o rezultatih nacionalne gozdne inventure 2020 : prvi panel vzorčne mrežeMitja Skudnik, Gal Kušar, Jernej Jevšenak, Anže Martin Pintar, 2022, elaborat, predštudija, študija Ključne besede: gozdovi, gozdarstvo, monitoring, nacionalna gozdna inventura, odmrla lesna biomasa, temeljnica, površina gozda, lesna zaloga, vzorčne ploskve, poročila Objavljeno v DiRROS: 15.03.2022; Ogledov: 805; Prenosov: 0 |
25. Obstoj, branost in kakovost revije Gozdarski vestnik so odvisni od nas vsehMitja Skudnik, Polona Hafner, 2022, predgovor, uvodnik, spremna beseda Ključne besede: obstoj revije, branost revije, kvaliteta revije, Gozdarski vestnik, strokovne revije, gozdarstvo Objavljeno v DiRROS: 08.03.2022; Ogledov: 799; Prenosov: 259 Celotno besedilo (44,23 KB) |
26. Sistem opredelitve rabe tal na ploskvah nacionalne gozdne inventure 2022 (gozd/drugo gozdno zemljišče/negozd) : seminar : online seminar v organizaciji Oddelka za načrtovanje in monitoring gozdov in krajine, Gozdarski inštitut Slovenije, Ljubljana, 31. 1. in 1. 2. 2022, onlineAnže Martin Pintar, Andrej Grah, Mitja Skudnik, 2022, druga izvedena dela Ključne besede: gozdarstvo, gozdovi, negozd, definicija gozda, druge gozdne površine, nacionalna gozdna inventura, gozdna inventura, fotointerpretacija, gozdni rob, raba tal, terenski popis Objavljeno v DiRROS: 24.02.2022; Ogledov: 845; Prenosov: 0 |
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28. Growing stock monitoring by European National Forest Inventories : historical origins, current methods and harmonisationThomas Gschwantner, Iciar Alberdi, Sébastien Bauwens, Susann Bender, Dragan Borota, Michal Bošela, Olivier Bouriaud, Johannes Breidenbach, Janis Donis, Christoph Fischer, Mitja Skudnik, 2022, izvirni znanstveni članek Povzetek: Wood resources have been essential for human welfare throughout history. Also nowadays, the volume of growing stock (GS) is considered one of the most important forest attributes monitored by National Forest Inventories (NFIs) to inform policy decisions and forest management planning. The origins of forest inventories closely relate to times of early wood shortage in Europe causing the need to explore and plan the utilisation of GS in the catchment areas of mines, saltworks and settlements. Over time, forest surveys became more detailed and their scope turned to larger areas, although they were still conceived as stand-wise inventories. In the 1920s, the first sample-based NFIs were introduced in the northern European countries. Since the earliest beginnings, GS monitoring approaches have considerably evolved. Current NFI methods differ due to country-specific conditions, inventory traditions, and information needs. Consequently, GS estimates were lacking international comparability and were therefore subject to recent harmonisation efforts to meet the increasing demand for consistent forest resource information at European level. As primary large-area monitoring programmes in most European countries, NFIs assess a multitude of variables, describing various aspects of sustainable forest management, including for example wood supply, carbon sequestration, and biodiversity. Many of these contemporary subject matters involve considerations about GS and its changes, at different geographic levels and time frames from past to future developments according to scenario simulations. Due to its historical, continued and currently increasing importance, we provide an up-to-date review focussing on large-area GS monitoring where we i) describe the origins and historical development of European NFIs, ii) address the terminology and present GS definitions of NFIs, iii) summarise the current methods of 23 European NFIs including sampling methods, tree measurements, volume models, estimators, uncertainty components, and the use of air- and space-borne data sources, iv) present the recent progress in NFI harmonisation in Europe, and v) provide an outlook under changing climate and forest-based bioeconomy objectives. Ključne besede: forest history, natural resources, sustainability, timber volume, sampling, remote sensing, bioeconomy, climate change Objavljeno v DiRROS: 14.12.2021; Ogledov: 754; Prenosov: 535 Celotno besedilo (17,73 MB) Gradivo ima več datotek! Več... |
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