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Aluvialne pahljače so dinamično sedimentacijsko okolje, v katerem se prepletajo tako gravitacijski kot aluvialni sedimentacijski procesi, ki za seboj pustijo značilne sedimentne faciese. Preplet gravitacijskih in aluvialnih sedimentnih faciesov je še posebej značilen za pahljače v gorskem okolju. Primer doline, ki so jo v holocenu začeli zasipavati sedimenti na številnih aluvialnih pahljač, je dolina Planice v severozahodni Sloveniji. Doktorska disertacija je namenjena detajlni sedimentološki analizi holocenskih sedimentacijskih procesov na aluvialnih pahljačah v gorskem okolju, njihovemu časovnem in prostorskem pojavljanju ter dejavnikom, ki vplivajo na njihovo sprožitev. Facielna analiza vključuje opis sedimentnih struktur, tekstur ter litologije zrn. Opravili smo jo na sedimentih odloženih na površju pahljač ter v detajlnih sedimentoloških profilih. Starost sedimentnih nanosov smo določili z dendrogeomorfološko metodo ter radiokarbonskimi datacijami. Datiranim nanosom smo pripisali sprožitvene meteorološke dogodke, ki jih je zabeležila meteorološka postaja Rateče. Pri določevanje sedimentnih faciesov in morfoloških značilnosti pahljač smo uporabili tudi metode daljinskega zaznavanja (lidarske posnetke ter brezpilotni letalnik). Z georadarjem smo opravili podpovršinske raziskave. Skupno smo določili osem sedimentnih faciesov. Šest jih je značilnih za aluvialna sedimentacijska okolja in se pojavljajo predvsem tam, kjer preperevanje kamninske podlage ne tvori drobnozrnatih (muljastih) sedimentov. Le dva faciesa sta značilna za gravitacijske (drobirske in blatne) masne tokove, ki se pojavljajo le na lokacijah, kjer pri preperevanju kamninske podlage nastaja večja količina muljastega sedimenta. Sedimentološki podatki, datacije, povezava sedimentnih procesov s sprožitvenimi dogodki, podatki daljinskega zaznavanja in podpovršinske raziskave dokazujejo, da aluvialne pahljače gradijo predvsem aluvialni sedimentacijski procesi, ki jih prožijo pogosta 24-urna deževja z več kot 50 mm padavin. Sedimentacijski procesi gravitacijskih tokov so redkejši, vendar destruktivnejši in so pogojeni z zaledno litologijo. Alluvial fans are a dynamic sedimentary environment where a set of sedimentary facies typical of alluvial and gravity sedimentary process occur. Such interlinked occurrence of sedimentary processes is typical for alluvial fans in the alpine environment. An example of an alpine valley is the Planica Valley in northwest Slovenia, which is covered by numerous Holocene alluvial fans. Multimethod research of this dissertation is focused on detailed sedimentary analysis of Holocene sedimentary deposits which built a set of typical alpine alluvial fans, spatio-temporal presence of these process and factors which contribute to their occurrence. Sedimentary analysis of facies is based on structure, texture, and lithology of sediment documented on fan’s surfaces and in sedimentary profiles. Sedimentary deposits were dated using dendrogeomorphology and radiocarbon dating. Dated deposits were related to triggering rainfall events monitored at the Rateče meteorological station. Processes and alluvial fan landforms were also defined using remote sensing techniques (lidar and unmanned aerial vehicle). Ground-penetrating radar technique was applied to understand subsurface geometry. We classified eight sedimentary facies, mostly typical for alluvial sedimentary environments. They occur where the bedrock does not weather into fine-grained (mud) sediment. Only two facies are typical for gravitational (debris and mud) flow, which occur at places with bedrock that weathers into large amounts of fine-grained sediment. Sedimentary analysis, dating of deposits, relating dated deposits to triggering rainfall events, remote sensing and subsurface data prove that alluvial fans are predominantly built by alluvial sedimentary processes during frequent 24-hour rainfalls that exceed 50 mm. Gravitational mass movement sedimentary process are much less frequent, however much more destructive and conditioned by bedrock lithology.

Drevesa so pomemben arhiv podatkov o preteklih dogodkih za rekonstrukcijo prostorske in časovne aktivnosti skalnih podorov, saj beležijo vplive skalnih podorov z anomalijami v rasti drevesnih branik ali prek vizualnih poškodb, vidnih na površju debel. V prispevku je predstavljena metodologija preučevanja skalnih podorov z analizo vidnih poškodb na deblu 52 dreves navadne bukve (Fagus sylvatica L.) na območju doline Trente v Sloveniji. Na podlagi analize smo ugotovili, da je povprečno število poškodb na posamezno drevo 7 ter da večinoma spadajo v kategorijo starih poškodb, kar kaže na manjšo aktivnost skalnih podorov v zadnjih letih. Povprečna povratna doba pojavljanja skalnih podorov je znašala 31,8 let le-ta pa se skrajša za 1,2 leta, če upoštevamo pogojno verjetnost vpliva, da skale lahko zgrešijo drevesa. Prostorsko pojavljanje skalnih podorov kaže na večjo aktivnost v osrednjem delu preučevanega pobočja. Trees represent an important archive that can be used to reconstruct the spatial and temporal patterns of rockfall events. Rockfall impacts can be recorded in the form of anomalies in tree rings and impact scars on the tree stem. In this paper we demonstrate the use of an approach based on counting scars for reconstructing the frequency and spatial pattern of past rockfalls. The approach was applied by counting the visible scars on the stem surface of 52 European beech trees (Fagus sylvatica L.) in the area of the Trenta Valley, Slovenia. The average number of impacts per trees was 7, and the impacts were mostly classified as old, indicating reduced rockfall activity in recent years. The average recurrence interval was 31.8 years, which was reduced by 1.2 years by the application of the conditional impact probability. The spatial pattern of rockfall impacts shows that rockfall activity is higher in the middle part of the studied slope.

Debris flows can transport large amounts of material and therefore present a significant threat to infrastructure and human life. In this research, we used tree-ring width analyses to quantify the response of trees to three debris flow events in NW Slovenia (Javoršček, Srpenica) and W Slovenia (Nikova) for which we know the time of origin. We attempted to date these and similar tree responses in the past and compared the patterns between different tree species. Altogether, we sampled 147 trees across a range of tree species (Fagus sylvatica, Pinus sylvestris, Fraxinus excelsior, Fraxinus ornus, Acer pseudoplatanus, Picea abies, Juglans regia, Acer campestre, Tilia cordata and Ostrya carpinifolia), including reference trees that were outside the debris flow fan. For 91 trees, we constructed tree-ring chronologies and used pointer-year analysis to identify years that had abnormal growth. For the remaining trees (mostly Ostrya carpinifolia, Tilia cordata and Acer pseudoplatanus), we either could not accurately distinguish tree rings or two samples from a single tree showed significantly different growth patterns. The growth patterns of Fagus sylvatica and Picea abies following debris flow events showed a weak response at the Javoršček site and no clear responses at the other two sites. Tree species responded similarly at the same locations. Due to the lack of a clear response pattern, we were not able to reconstruct past debris flows. Drobirski tokovi s sposobnostjo prenašanja večjih količin materiala so nevarni za infrastrukturo in življenje ljudi. Z analizo širine lesnih branik smo v raziskavi poskušali prepoznati odziv dreves na vpliv treh drobirskih tokov v SZ Sloveniji (Srpenica, Javoršček) in Z Sloveniji (Nikova) z znanim časom nastanka, na podlagi spremembe širine branike datirati podobne drobirske tokove v preteklosti in primerjati odzive različnih drevesnih vrst. Na treh lokacijah smo vzorčili skupno 147 dreves različnih drevesnih vrst (Fagus sylvatica, Pinus sylvestris, Fraxinus excelsior, Fraxinus ornus, Acer pseudoplatanus, Picea abies, Juglans regia, Acer campestre, Tilia cordata in Ostrya carpinifolia), vključno z referenčnimi drevesi, ki niso bila izpostavljena delovanju dejavnika. Pri 91 drevesih smo uspešno izdelali drevesne kronologije in z uporabo metode značilnih let ugotovili leta, ki so pri posameznih drevesnih vrstah ter na posameznih lokacijah glede na širno branike kazala zelo različne trende rasti. Pri drugih drevesih vrstah (večinoma Ostrya carpinifolia, Tilia cordata in Acer pseudoplatanus) nam ni uspelo razbrati vseh branik, oz. sta bili po dve zaporedji širin branik istega drevesa različni. V analizi rasti za prvo leto po dogodku smo šibak odziv na vpliv drobirskih tokov zaznali na lokaciji pod Javorščkom, ne pa tudi v Srpenici in Nikovi. Različne drevesne vrste so se na istih lokacijah odzvale podobno. Ker smo zaznali odziv le na eni lokaciji, nismo mogli rekonstruirati drobirskih tokov po posameznih lokacijah v preteklosti.

Trees represent an important archive that can be used to reconstruct the spatial and temporal patterns of rockfall events. Rockfall impacts can be recorded in the form of anomalies in tree rings and impact scars on the tree stem. In this paper we demonstrate the use of an approach based on counting scars for reconstructing the frequency and spatial pattern of past rockfalls. The approach was applied by counting the visible scars on the stem surface of 52 European beech trees (Fagus sylvatica L.) in the area of the Trenta Valley, Slovenia. The average number of impacts per trees was 7, and the impacts were mostly classified as old, indicating reduced rockfall activity in recent years. The average recurrence interval was 31.8 years, which was reduced by 1.2 years by the application of the conditional impact probability. The spatial pattern of rockfall impacts shows that rockfall activity is higher in the middle part of the studied slope. Drevesa so pomemben arhiv podatkov o preteklih dogodkih za rekonstrukcijo prostorske in časovne aktivnosti skalnih podorov, saj beležijo vplive skalnih podorov z anomalijami v rasti drevesnih branik ali prek vizualnih poškodb, vidnih na površju debel. V prispevku je predstavljena metodologija preučevanja skalnih podorov z analizo vidnih poškodb na deblu 52 dreves navadne bukve (Fagus sylvatica L.) na območju doline Trente v Sloveniji. Na podlagi analize smo ugotovili, da je povprečno število poškodb na posamezno drevo 7 ter da večinoma spadajo v kategorijo starih poškodb, kar kaže na manjšo aktivnost skalnih podorov v zadnjih letih. Povprečna povratna doba pojavljanja skalnih podorov je znašala 31,8 let le-ta pa se skrajša za 1,2 leta, če upoštevamo pogojno verjetnost vpliva, da skale lahko zgrešijo drevesa. Prostorsko pojavljanje skalnih podorov kaže na večjo aktivnost v osrednjem delu preučevanega pobočja.

Tree ring eccentricity was used to reconstruct landslide activity in the last 138 years in the Urbas landslide located at Poto&scaron, ka planina in the NW part of the Karavanke Mountains, Slovenia. The research was based on the dendrochronological sampling of Norway spruce (Picea abies (L.) Karst.) in areas of varying landslide intensity. Analysis of a sudden change in the eccentricity index of 82 curved trees concluded that there were 139 growth disturbances and 16 landslide reactivations between 1880 and 2015, with a landslide return period of 8.5 years. Using lidar data, changes in the surface of the digital terrain model (DTM) were compared with changes in the eccentricity index of trees at the same location in the period 2014&ndash, 2017. On the basis of temporal changes in the eccentricity index and by using spatial interpolation, landslide activity was reconstructed for the period 1943&ndash, 2015. During this period, landslide intensity increased in the central part of the landslide. Although categorization into seven categories of different stem curvature was proposed, no distinction between categories with respect to their eccentricity index was found.