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Drevesna sestava jelovo-bukovih gozdov se v prostoru in času spreminja. Nanjo vplivajo številni naravni in antropogeni dejavniki, ki delujejo neposredno ali posredno. Oblikovanje usmeritev za gojenje gozdov zato zahteva dobro poznavanje delovanja lokalnih ekoloških, zgodovinskih, gospodarskih in splošnih okoljskih dejavnikov. V prispevku prikazujemo sintezo štirih skupin raziskav, ki smo jih izpeljali v dinarskih jelovo-bukovih gozdovih v zadnjem desetletju in obravnavajo: 1) ekologijo pomlajevanja v manjših in srednjih vrzelih, 2) odziv sestojev v pragozdu Perućica na motnje srednjih jakosti (vetrolomi), 3) dolgoročne spremembe v vrstni sestavi pragozdov v jugovzhodni Evropi, in 4) odvisnost pomlajevanja v gospodarskih gozdovih od gozdnogojitvenega sistema. Namen prispevka je prikazati vlogo jelke v razvoju jelovo-bukovega gozda ter poudariti procese, ki vodijo v njeno sobivanje ali izločanje. Raziskave ekologije pomlajevanja nakazujejo, da je jelka uspešnejša na posebnih mikrorastiščih (hladnejše in vlažnejše razmere, odmrla drevesa, večja skalovitost, nižji pH tal, skromne svetlobe razmere). Na vetrolomnih površinah srednjih jakosti prevlada bukev, jelka pa se nasemeni kasneje v strnjena bukova mladovja. Naše raziskave niso potrdile hipoteze o lažjem uveljavljanju jelke v večjih sestojnih vrzelih gospodarskih gozdov. Spremembe vrstne sestave pragozdov v Sloveniji in jugovzhodni Evropi nakazujejo nazadovanje jelke v zadnjih petdesetih letih, kar je posledica več skupin vzrokov, še posebej zračnega onesnaženja in objedanja po divjadi. V Sloveniji je zmanjševanje deleža jelke v Dinaridih izrazito hitro. Primerjave z jugovzhodno Evropo kažejo, da so sicer raznovrstne strategije uveljavljanja jelke v Sloveniji neuspešne zaradi visokih gostot velikih rastlinojedih parkljarjev. The tree species composition of silver fir and beech forests has changed in space and time due to a number of direct and indirect natural and anthropogenic causal factors. Forming silvicultural guidelines, therefore, requires a sufficient understanding of the ecological, historical, economic and general environmental factors that influence silver fir-beech forests. In this paper, we present a synthesis of four research projects carried out in Dinaric silver fir-beech forests in the last decade: 1) regeneration ecology in small and medium canopy gaps 2) stand response to intermediate wind disturbance in the old-growth silver fir-beech Perućica forest 3) long-term changes in tree species composition of old-growth forests in South East Europe and 4) interdependence between regeneration and silvicultural systems.The aim of the paper is to show the role of silver fir in the development of silver fir-beech forest, and to highlight the processes that lead to its coexistence or exclusion. Research on the ecology of regeneration suggests that silver fir regenerates better on special microsites (e.g. coolersites with more soil moisture, CWD, high rock coverage, lower pH of the soil, poor light conditions). In medium sized gaps beech is dominant, while silver fir establishes itself later under the young beech canopy. Our research did not confirm the hypothesis of better regeneration success of silver fir in larger canopy gaps in managed forests. Repeated inventories from forest reserves in Slovenia and South-Eastern Europe show that silver fir declined in the last fifty years due to a variety of causes, primarily from air pollution and ungulate browsing. In Slovenia in particular, a drastic reduction of the share of silver fir occurred rapidly. Comparisons with South-Eastern Europe suggest that a wide range of regeneration strategies of silver fir in Slovenia failed because of high densities of ungulates.

Pragozdni rezervati so odličen objekt za analizo naravnega razvoja sestojev, ki poteka brez vpliva človeka, oziroma je ta močno zmanjšan. Leta 1984 so bile v Rajhenavskem Rogu postavljene stalne raziskovalne ploskve s skupno površino 1,91 ha, namenjene analizi odraslega sestoja. Leta 2020 je bila izvedena peta ponovitev popisa. Smrtnosti in vrasti jelke in bukve si niso podobne in se skozi čas spreminjajo. V celotnem obdobju ni bilo zaznane vrasti jelke skozi merski prag. Prav tako so se močno zmanjšale njene gostote v prvem debelinskem razredu (DBR), čemur vzrok so predvsem velike populacije jelenjadi. Stalno odmiranje in pomanjkanje vrsti jelke je privedlo do splošnega upada jelke skozi vse DBR. Nasprotno, število bukve v prvem DBR skozi vsa obdobja vztrajno narašča, njena vrast pa je vidna tudi v ostalih DBR. Ti trendi napovedujejo vztrajno nadomeščanje jelke z bukvijo, kar lahko dolgoročno privede do spremenjene drevesne sestave. V zadnjih treh meritvah je opazno večanje števila živih-zlomljenih dreves, od vetra izruvanih dreves in dreves, ki so podlegla padcem drugih dreves, kar kaže na večanje ekstremnih vremenskih pojavov, predvsem manjših vetrolomov. Old-growth reserves serve as natural laboratories for analysing the dynamics of forest stands without direct influence of humans. In 1984, permanent research plots were placed in the Rajhenavski Rog with a total area of 1.91 ha intended for the analysis of long-term demography. A fifth iteration of the census was carried out in 2020. Mortality and recruitment of beech and fir, the two dominant species, varied over time. Throughout the monitoring period, no ingrowth of the fir was detected, and its density in small diameter classes declined over time, likely due to large populations of red deer. The lack of recruitment and continuous mortality also resulted in a general decline in fir across all diameter classes. In contrast, the number of beech in the smallest diameter class has steadily increased over time, and recruitment of beech is notable across most diameter classes. These trends highlight a steady replacement of fir by beech, which may lead to a long-term change in species composition at the site. In the last three measurements, there has been an increase in the number of live-snapped, uprooted, crushed trees, indicating an increase in disturbance induced tree mortality, especially smaller windthrow events.

V gozdnem rezervatu Repiško smo leta 2014 izvedli ponovno polno premerbo drevja na trajni raziskovalni ploskvi. Šlo je za prvo ponovitev po popisu ničelnega stanja v letu 1986. Poleg tega smo postavili še sistematično mrežo vzorčnih ploskev v rezervatu Tisovec in Repiško. Namen naloge je bil preko gostote, debelinske strukture, smrtnosti in pomlajevanja prikazati dinamiko sestoja. Na trajni ploskvi v rezervatu Repiško nismo beležili večjih sprememb v drevesni sestavi. S 43 % deležem je v skupnem številu dreves še vedno vodila jelka, pred smreko in bukvijo (obe 23 %). Povprečna velikost temeljnice v Tisovcu je znašala 57,33 m2/ha, v Repiškem pa 53,91 m2/ha. V obeh primerih se je največje število osebkov nahajalo v debelinskem razredu do 30 cm. Tudi na mreži ploskev smo ugotovili primerljivo vrstno sestavo in nekoliko višjo gostoto (663 dreves/ha). V Tisovcu je znašala gostota 887 dreves/ha. Med vrstami pa so prevladovale bukev (36 %), jelka (25 %) in smreka (19 %). Stopnja smrtnosti v Repiškem je znašala 0,61 %/leto. Najvišje stopnje smo beležili v prvem debelinskem razredu. Povprečni volumen odmrlega lesa v Tisovcu je znašal 46,5 m3/ha in se je večinoma nanašal na mokovec in bukev, v Repiškem pa je večina 116,0 m3/ha volumna odmrlih drevesnih ostankov odpadla na jelko. V obeh primerih so v volumnu prednjačile podrtice. V obeh rezervatih ugotavljamo primerljive gostote pomladka. V Tisovcu smo zabeležili 14.440 rastlin/ha, med katerimi je z 39 % prevladoval gorski javor. V Repiškem pa je med 13.620 rastlin/ha vodilno vlogo igrala jelka (48 %). Pomlajevanje je v obeh primerih zadovoljivo. Večje poškodbe po parkljasti divjadi niso zaznavne. In 2014 we carried out a full repetition of measurements on the permanent research plot in the Repiško forest reserve. It was the first re-measurement following the initial establishment in 1986. In addition, we set up a systematic grid of sample plots in the Repiško and Tisovec reserves. The aim of the thesis was to infer stand dynamics using measurements of density, diameter structure, mortality, and regeneration. We did not record any significant changes in species composition on the permanent plot in Repiško. With a 43 % share of the total number of trees fir still prevailed over spruce and beech (both 23 %). The average basal area in Tisovec was 57,33 m2/ha and 53,91 m2/ha in Repiško. In both cases, the largest number of stems was located in the diameter class up to 30 cm. On the sampling grid, we found comparable species composition and slightly higher density (663 trees/ha). In Tisovec the density was 887 trees/ha. The dominant species were beech (36 %), fir (25 %) and spruce (19 %). The mortality rate in Repiško was 0,61 %/year. The highest mortality rates were recorded in the first diameter class. The average dead tree volume in Tisovec was 46,5 m3/ha and was mostly related to whitebeam and beech. In Repiško fir contributed most to the 116,0 m3/ha volume of dead tree remnants. Logs were prevalent type of dead wood in both cases. In both reserves we found comparable regeneration densities. We recorded 14.440 stems/ha in Tisovec, of which 39 % were sycamore. In Repiško fir was the most abundant (48 %) of the total 13.620 stems/ha. Regeneration was satisfactory in both cases. We did not detect major deer damage.

V pragozdu Perućica v Bosni in Hercegovini smo raziskali vpliv treh srednjepovršinskih vetrolomov na razvoj gozdov v vetrolomnih vrzelih. Na vsaki vetrolomni površini smo postavili tri raziskovalne ploskve, velikosti 25 x 25 m. Na enak na%in smo postavili raziskovalne ploskve v kontrolnih sestojih. Na raziskovalnih ploskvah na vetrolomih smo izmerili vsa stoje%a drevesa in mladovje. Na vsaki raziskovalni ploskvi na vetrolomu smo odvzeli izvrtke desetim drevesom, ki so bila najbliţje središ%u ploskve. Izvrtke smo odvzeli tudi desetim drevesom ve%jih dimenzij na celotni površini vetroloma. Izmerili smo vsa razpadajo%a drevesa ter jih razvrstili v pet razredov glede na stopnjo razgradnje. Zgradba sestojev se je po vetrolomih spremenila. Svetloljubni listavci se pojavijo, %e je dovolj svetlobe, v nasprotnem primeru se pojavi bukev. Najprej se pojavijo svetloljubni listavci, za njimi bukev in šele na koncu jelka. Vsak vetrolom je posledica ene ve%je ujme. Nastala vrzel se je po ujmi po%asi širila. Na vetrolomih Osoje in Tunjemir se je pestrost drevesnih vrst pove%ala, ne pa tudi na vetrolomu Skakavac. Mladje svetloljubnih listavcev se je pojavilo po vetrolomih, mladje sencozdrţnih drevesnih vrst je bilo prisotno ţe pred motnjami. Bukev bolj odreagira na pove%an dotok svetlobe kot jelka. Povpre%ni debelinski prirastek gorskega javorja je najve%ji pri drevesih, ki so vzklila po vetrolomu. Srednjepovršinski vetrolomi pomembno vplivajo na razvoj gozdov. In the Perućica old-growth forest in Bosnia and Herzegovina, we investigated the impact of three intermediate wind disturbances upon the forest development of windthrow gaps. Three research areas 25 x 25 m were prepared in each windthrow gap. Research areas were prepared in the same way also in control stands. In the research areas, all standing trees and young growths were measured. In each research area in the windthrow gaps, core samples were taken from ten trees that were closest to the centre of the area. Core samples were taken also from ten larger trees in the entire windthrow surface. All decaying trees were measured and they were classified into five classes, depending on the level of decomposition. The structure of stands changed after windfall. Deciduous trees that prefer ample light conditions appear in case of ample light, otherwise beeches apper. First, decidiuous trees appear, followed by beeches and finally by firs. Each windfall results from a larger natural disaster. A gap caused by a natural disaster spreads slowly. In windfalls Osoje and Tunjemir, the variety of tree species increased, which does not apply for the windfall Skakavac. The growth of decidiuous trees that prefer ample light conditions appeared after wind disturbances, whereas the growth of shade-tolerant tree species was present already before the disturbances. Beeches reacts more strongly to more ample light than firs. The average radial growth of sycamore maple is largest in case of trees that germinated after the wind disturbance. Intermediate wind disturbances have a significant impact upon forest development.

V pragozdnem ostanku Rajhenavski Rog so bile leta 1984 izločene tri stalne raziskovalne ploskve s skupno površino 1,91 ha, ki so bile izmerjene tudi leta 1994. Leta 2010 smo ponovili meritve na vseh treh ploskvah. Preučevali smo spreminjanje velikosti vrasti in smrtnosti v obdobjih 1984-1994 in 1994-2010. Skupna letna smrtnost se je v obdobju 1994-2010 v primerjavi z obdobjem 1984-1994 iz 1 % povišala na 1,2 %, stopnja smrtnosti jelke (Abies alba Mill.) pa je v obeh meritvenih obdobjih močno presegala stopnjo smrtnosti bukve (Fagus sylvatica L.). Do največjega povišanja smrtnosti je prišlo, tako pri jelki kot pri bukvi, pri drevesih s premerom večjim od 70 cm. Skupna letna vrast 1,8 % v obdobju 1984-1994 se je povišala na 2,6 % v obdobju 1994-2010. Prišlo je do izrazitega povečanja vrasti novih bukovih dreves v populacijo, vrasti jelke pa že od prvih meritev leta 1984 nismo zaznali. Skupna vrast se je povišala pri drevesih s premerom do 20 cm, pri debelejših drevesih pa se je vrast v obdobju 1994-2010, v primerjavi z obdobjem 1984-1994, znižala. Število bukev na ploskvah se viša in sedaj znaša 84 % vseh dreves, delež jelke pa se je znižal na 16 %. Rezultati nakazujejo na nadaljnje zmanjševanje deleža jelke v populaciji in vse večjo prevlado bukve v Rajhenavskem pragozdu. In 1984 three permanent plots totalling 1,91ha were established in the Rajhenavski Rog old-growth forest. These plots were re-measured in 1994 and 2010. We quantified mortality and recruitment rates in two periods: 1984-1994 and 1994-2010. The annual mortality rate increased from 1% in 1984-1994 to 1,2% in 1994-2010. The mortality rate of silver fir (Abies alba Mill.) heavily exceeded that of European beech (Fagus sylvatica L.) in both of the analyzed periods. The highest increase in mortality was recorded for trees with dbh greater than 70 cm for both silver fir and European beech. The annual recruitment rate increased from 1,8% in 1984-1994 to 2,6% in 1994-2010. We recorded a large increase in the recruitment of beech trees in the 1994-2010 period, while there was no recruitment of silver fir in the last 26 years. For trees with dbh lower than 20 cm, we recorded an increase in annual recruitment, while a decrease in recruitment was found for trees with dbh greater than 20 cm. The number of beech trees on the plots increased and as a result beech currently represents 84% of all trees. The share of silver fir in the forest decreased and the results suggest this process will also continue in the future, leading to a further increase in beech in the Rajhenavski Rog old-growth forest.

Namen diplomskega dela je preučiti vzajemno delovanje dveh motenj, ki vplivata na pomlajevanje: nastanka vrzeli zaradi odmiranja jelke in objedanja jelenjadi in srnjadi na pomlajevanje v Kočevskem Rogu. Za raziskovalni objekt je bil izbran Rajhenavski pragozd. Sedanje stanje podmladka so primerjali s stanjem v letu 1984. Za primerjavo je bila analizirana sestava mladja v bližnjih ogradah izven pragozda. Ugotovljeno je, da je Rajhenavski pragozd močno izpostavljen selektivnemu objedanju predvsem jelenjadi, gostota jelk je 132 rastlin/ha, gostota javorja je 212 rastlin na ha, medtem ko je gostota bukve 13928 rastlin/ha. V ograjah v bližini so rezultati močno razlikujejo: bukev 8627 rastlin/ha, jelka 4993 rastlin/ha, javor 8007 rastlin/ha Gostota jelenjadi se je povečala v zadnjih 50 letih in območje Rajhenavskega pragozda ji zagotavlja ugodne habitatne razmere. Na dolgoročno vrstno zgradbo in na zmanjšanje števila vrst v Kočevskem Rogu bo vplival vrstno-specifični odziv naveč različnih, medsebojno vplivajočih motenj in okoljskih dejavnikov. The purpose of this research was to study the mutual effects of fir decline and deer browsing on tree regeneration in Kočevski Rog. The first part of the study was conducted in an old-growth forest of Rajhenav. The current number of tree saplings and seedlings was compared to the data from 1984. To further compare, an identical study was performed in the fenced areas in the vicinity of Rajhenav forest, where the effect of deer browsing is eliminated. The conclusion is that Rajhenav old-growth forest is under severe selective browsing pressure. The density of fir seedlings is 132/ha, the density of maple seedlings is 212/ha, while the average beech density is 13928/ha. The numbers in fences are significantly different: 8627 beech saplings and seedlings/ha, 4993/ha for fir and 8007/ha for maple. The population density of deer has rapidly increased in the past 50 years and the Rajhenav old-growth forest provides a favorable habitat conditions. The long-term tree species distribution and reduced diversity resulted from species-specific responses to interacting disturbances and environmental factors.