Krajinske spremembe na območju Pivke, Slovenija

Spontaneous afforestation is one of the biosystemic landscape change processes affecting landscape functioning. The process of overgrowing is highly dynamic, and the temporal dimension of changes in landscape structure can be of key importance for evaluating habitat suitability. A detailed study was carried out in the area of 19.52 km2 within the Pivka municipality, where land use is a mixture of traditional farmland, forests, and extended areas of abandoned former farmland with natural re-growth. In addition, this area is highly important for two bird species: the Barred Warbler (Sylvia nisoria) and the Red-backed Shrike (Lanius collurio). Both species are sensitive to forest spreading and prefer a mixture of extensive meadows with shrubs and hedgerows as their most suitable habitat. Digital BW orthophotos from the 1975 - 2000 period and colour digital orthophotos from 2009 have be enused for on screen digitizing of the EUNIS habitat classes. Indicators of landscape changes were derived from temporal based difference in the landscape structure (different structural indicators based on patch size, shape, distances and patch dynamics). All the details obtained were evaluated based on Earth observation data and GIS supported methods. The most valuable parts of the area for both species are, from a biodiversity point of view, the core forest areas and mixture of meadows with shrubs and hedgerows.Spontano zaraščanje je eden izmed biosistemskih procesov sprememb, ki vplivajona delovanje krajine. Zaraščanje je dinamično in časovna dimenzija sprememb v krajinski zgradbi je lahko ključnega pomena za ocenjevanje primernosti habitatov. Podrobnejšo analizo smo izpeljali na 19,52 km2 izbrane površine v občini Pivka, kjer gre za prostor, kjer je raba zemljišč preplet tradicionalnih kmetijskih zemljišč, gozdov in obsežnih predelov zaraščajočih se kmetijskih površin. Poleg tega je to območje zelo pomembno za dve vrst ptic: pisano penico (Sylvia nisoria) in rjavega srakoperja (Lanius collurio). Obe vrsti sta občutljivi za širjenje gozda, saj je njun habitat preplet ekstenzivnih travnikov z grmičevjem in živicami. Za zaslonsko digitalizacijo habitatnih razredov EUNIS smo uporabili digitalne črno-bele ortofoto posnetke iz obdobja 1975 - 2000 in barvni digitalni ortofoto iz leta 2009. Kazalce krajinskih sprememb smo izpeljali iz razlike v zgradbi krajine iz različnih let (različni kazalniki krajinske zgradbe, ki temeljijo na velikosti in obliki zaplat, medsebojnih razdaljah med njimi in časovni dinamiki). Vse pridobljene podatke smo ovrednotili na podlagi daljinsko pridobljenih podatkov v okolju GIS. Najvrednejši deli prostora so jedrne cone gozdov in prepleti travnikov z živicami in grmovjem

The current distribution of Black locust (Robinia pseudoacacia L.) in Slovenia and predictions for the future

V raziskavi smo ugotavljali lesno zalogo robinije (Robinia pseudoacacia L.) in njen delež v gozdovih Slovenije. Poleg tega smo z uporabo empiričnega modela in scenarijev podnebnih sprememb napovedali njeno pojavljanje in delež v prihodnost. Robinija je trenutno najbolj pogosta tujerodna drevesna vrsta v naših gozdovih. Sedanja lesna zaloga robinije dosega okoli 0,6 % celotne lesne zaloge naših gozdov. Najpogostejša je v gozdovih GGO Murska Sobota in Kraškega GGO. Ob uresničitvi scenarijev podnebnih sprememb, ki vsi predvidevajo povečanje povprečnih temperatur zraka v prihodnosti, se bo delež lesne zaloge robinije postopoma še povečeval na vzhodnem in severovzhodnem ter jugozahodnem delu Slovenije. Večji delež lahko pričakujemo tudi v nižinskem in gričevnem delu osrednje Slovenije. Po napovedih modela bi se lahko lesna zaloga robinije do konca stoletja najmanj podvojila glede na današnje stanje. Ob uresničitvi scenarijev podnebnih sprememb bi se gozdarstvo srečevalo še z večjimi težavami, povezanimi s to invazivno tujerodno drevesno vrsto. Ob doslednejšem uresničevanju konceptov sonaravnega gozdarstva bomo morali na čim bolj optimalen način usklajevati med nezaželenostjo te invazivne tujerodne vrste in njenimi številnimi koristmi ter interesi lastnikov.In this study, we analyse the growing stock of black locust (Robinia pseudoacacia L.) and its share in Slovenian forests. In addition, based on empirical model and climate change scenarios, we predict its distribution and share in the future. Black locust is the commonest non-native tree species in Slovenian forests. The current growing stock of black locust is near 0.6% of the total growing stock of our forests. This tree species has the highest share in forests of the Regional Unit of Murska Sobota and Regional Karst Area Unit (Sežana). Should the recent climate change scenarios, which all predict an increase in mean air temperature in the future, proved to be true, the share of the black locustʼ growing stock will increase gradually in the eastern, north-eastern and south-western parts of Slovenia. Higher share of this species can be expected also in the lowlands and hilly area of central Slovenia. According to the forecasts of the model, the black locustʼs growing stock could at least double in comparison with its present state by the end of the century. In such situation our forestry will be faced with even more difficulties associated with this invasive tree species. Through a more consistent implementation of the concepts of sustainability in forestry, the balance between this invasive alien species, which is less desirable in our forests, and its many benefits and interests of the forest owners needs to be found

The stability of forest areas in Slovenia as a criterion of landscape diversity and durability

Stabilnost notranjega okolja gozdov je pomemben kazalec biotske pestrosti na krajinskem nivoju, ko se odločamo o tem, ali bi določene gozdove lahko izkrčili. Zaradi tega smo se odločili, da ocenimo stabilnost notranjega gozdnega okolja v Sloveniji med letoma 1975 in 2012, saj so nam na voljo primerljivo dovolj natančni podatki o gozdni maski za teh 38 let. Štiri vrste sprememb pokrovnosti z gozdom (stabilni negozd, krčitve, zaraščanje in stabilni gozd) pojasnjujemo z empiričnim modelom v obliki odločitvenega drevesa, ki upošteva nadmorsko višino, naklon terena, talni tip, oddaljenost vsake celice na rastrski karti od gozdnega roba v izhodiščnem letu, oddaljenost vsake celice na rastrski karti od najbližjega naselja v izhodišč- nem letu. Pojasnjevalne modele smo zgradili po metodi strojnega učenja (Quinlan, 1986) z orodjem See5 (www.rulequest. com). Natančnost izbranega modela je znašala 74,65 %. V letu 2012 so stabilni gozdovi, katerih površina se od leta 1975 ni spreminjala, pokrivali 53 % Slovenije. Izmed vseh spremenljivk najbolje pojasnjujeta spremembo rabe začetna oddaljenost od gozdnega roba in deloma naklon terena. Oddaljenost od naselij in nadmorska višina nimata opaznega vpliva.The stability of forest core areas is an important indicator of biotic diversity on a landscape level in the process of deciding whether certain forests could be cleared. Consequently, we decided to estimate the stability of forest core areas in Slovenia between 1975 and 2012, as we are in possession of sufficiently accurate data to make a comparison of forest cover for these 38 years. Four types of changes in forest coverage (stable non-forest, deforestations, overgrowing and stable forest) are explained with an empiric model designed as a decision tree, which takes into account the altitude, the slope of the terrain, ground type, the distance of each cell on a raster map from the forest edge in the base year and the distance of each cell on a raster map from the nearest settlement in the base year. Explanatory models were built using the method of machine learning (Quinlan, 1986) using See5 (www.rulequest.com). The accuracy of the chosen model was 74.65%. In 2012, stable forests covered 53 % of Sloveniatheir coverage has remained unchanged since 1975. From all the variables, land-use changes are best explained by the initial distance from the forest edge and partially by the slope of the terrain. The distance from settlements and the altitude, on the other hand, do not play a significant role

New methods of prosessing aerial laser scanner data for forest ecosystem monitoring

The thesis is composed of two parts. In the first part we developed a new method for lidar\ud DTM generation. In the second part we used vertical lidar profiles for model-based prediction\ud of the percentages of individual tree species in the forest and to predict different light\ud properties of the forest In steep forested relief, the existing algorithms for computing DTM\ud from the lidar data have problems to distinguish between the ground returns and the\ud vegetation returns, because on the steep slopes the local cloud neighborhood has properties\ud similar to the vegetation. In the first part of the thesis we introduced a new method of DTM\ud computation from the lidar data, called REIN, which is especially adapted to the steep\ud forested topography. The method makes use of the lidar point redundancy to mitigate errors.\ud It does not belong into any of the known algorithm groups, because it randomly samples the\ud point cloud. REIN has a greater ability to adapt to variations in the terrain and forest cover.\ud Because of ensuring that each part of the area of interest gets equal probability of being\ud sampled, REIN results in a homogeneous DTM even under non-homogeneous data input\ud conditions. REIN also takes care of the problem of negative outliers due to multi-path\ud reflections. In the second part of the thesis we used vertical vegetation profiles, computed\ud from the small-footprint discrete lidar data, to predict the percentages of individual tree\ud species in the forest and to predict different light properties of the forest. The ensemble\ud methods of machine learning were used together with different combinations of the\ud explanatory variables, derived both from the discrete lidar data and from the aerial infra-red\ud imagery. The correlations for the eight best modeled target variables are between 0,76 and\ud 0,83. Relatively modest correlations are attributed to the heterogeneity of forests in the test\ud area, to the errors in the training set, and to the imprecise positioning of the field plots (due to\ud GPS errors under the forest canopy), resulting in a possible spatial shift between the field data\ud and lidar data. Infrared explanatory variables contribute the most to the predictions of target\ud variables referring to the tree composition. Lidar data are better suited to explain the forest\ud light properties, which in turn are linked to the spatial distribution of the above-ground forest\ud biomass. The machine-learned ensemble models are more accurate and more robust than the\ud linear regression models. The multi-target models are more suitable than the single-target\ud ensemble models, because the total time to set up a multi-target model is shorter than the time\ud needed to set up multiple single-target models. The multi-target models are also easier to\ud implement. The forest has been delimited into the forest stands by image segmentation based\ud on the model-based raster maps

The impacts of climate change on the expected spatial redistribution of forest vegetation types

V raziskavi smo simulirali prostorsko prerazporeditev tipov gozdne vegetacije v Sloveniji, do katere bi lahko prišlo ob pričakovanih podnebnih spremembah. Potencialne prostorske spremembe gozdne vegetacije so bile analizirane v GIS okolju s pomočjo empiričnega modela, ki napoveduje prostorsko razporeditev gozdne vegetacije v odvisnosti od podnebnih in drugih parametrov. Rezultati simulacij na osnovi treh podnebnih scenarijev kažejo, da se bo vzorec razporeditve gozdne vegetacije menjal pod vplivom podnebnih sprememb. Po napovedih bi lahko do leta 2070 prišlo do sprememb vegetacijskega tipa na več kot 75 % vseh gozdnih površin. Danes prevladujoči, pretežno bukovi gozdovi bi lahko bili v spremenjenih okoljskih razmerah močno prizadeti. Model napovedujepadec deleža prevladujočih mezofilnih bukovih gozdov s sedanjih 57 %na samo 3 % po pesimističnem scenariju in do 29 % po optimističnem scenariju.V toplejšem podnebju, ki ga predvidevajo vsi trije scenariji, bi se močno razširili različni termofilni gozdovi.The redistribution of forest vegetation types in Slovenia, driven by the expected climate change, has been simulated. The potential spatial changes of forest vegetation have been analyzed using empirical GIS model forecasting thespatial distribution of forest vegetation in relation to climate and other ecological parameters. Based on the three different climate scenarios, the simulations showed that the spatial pattern of forest vegetation will be altered under the impacts of climate change. According to the prediction in the year 2070, the vegetation type is likely to be changed on more than 75% ofall forest sites. Nowadays dominant forests, mostly beech, may be affected by such changing environmental conditions. The decrease of the actual prevailing mesic beech forest share from the present 57% to only 3% under the pessimistic scenario and up to 29% under the optimistic scenario could be expected. In a warmer climate, predicted by all three future scenarios, different thermophilous forests will be expanded over larger area of the countr

Dendrochronologycal analysis of the radial growth of Norway spruce (Picea abies (L.) Karst.) In its natural and secondary stands in Slovenia

Z dendrokronološkimi metodami smo analizirali debelinsko priraščanje smreke na osmih lokacijah v Sloveniji. Med njimi je bilo pet naravnih smrekovih združb, v druge je bila smreka umetno vnesena v preteklosti, oziroma je bil povečan njen naravni delež. Na vsaki ploskvi smo s prirastoslovnim svedrom odvzeli izvrtke najmanj 20 dreves. V dendrokronološkem laboratoriju smo jih posušili in zbrusili do visokega sijaja, nato pa skenirali s pomočjo sistema ATRICS ter izmerili širine branik v programih CooRecorder in CDendro. Ugotovili smo, da med naravnimi in antropogenimi rastišči ni značilnih razlik v debelinskem priraščanju. Na lokacijah Sorško polje, Ravnik in Mašun smo opazili spremembe v debelinskem priraščanju, ki kažejo, da se vpliv temperature zraka (toplejša poletja) in padavin (pogostejši pojav suše) na rast povečuje. Analiza značilnih let je pokazala, da so le-ta v zadnjih 30 letih pogostejša in da se pojavljajo na več lokacijah hkrati, predvsem pa se je povečalo število negativnih značilnih let, t.j. nadpovprečno toplih in suhih let.A dendrochronological analysis of the spruce\u27s radial increment at eight different plots was conducted throughout Slovenia. The plots selected were diverse: five of them were natural spruce standsin others, the spruce was introduced anthropogenically in the past for economic reasons, or its natural share in stands was increased. We took samples of at least 20 trees per plot and examined them in the dendrochronological laboratory using Advanced Tree-Ring Image Capturing System (ATRICS) and specialized dendrochronological software. We compared the growth in natural spruce stands with the secondary (anthropogenic) ones and found no statistical differences in growth patterns between these two groups. However, we found some evidence for climate change effect on radial increment at locations Sorško polje, Ravnik and Mašun, which indicates that air temperature and precipitation now have stronger effect on spruce growth than in the past. Analysis of pointer years suggests that extreme events (exceptionally warm and dry years) are more common and widespread in the last 30 years