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Climate is a strong predictor of the geographic distribution of tree species, and thus climate change may trigger shifts in the distribution of a tree species and/or its demographic structure. In the study, we aim to comprehensively compare the distributions of four life stages of European beech (Fagus sylvatica) (i.e., regeneration, recruitment, young trees and mature trees) in forests in Slovenia, Central Europe, which are characterized by strong gradients of elevation (ELV), temperature (TEMP) and precipitation (PREC) to detect possible shifts in distribution and demography. Beech life stages were surveyed on 3366 plots. To depict disparities between ELV, TEMP and PREC distributions of beech life stages, we applied several non-parametric methods: basic statistical tests to study differences in medians, means, and 1st and 9th deciles; generalized additive models to study shifts in the optimum; and extreme value analysis to study shifts at the trailing and leading edges. A substantial shift in juvenile beech stages upward and toward colder sites was detected. However, the shift was not uniform along the distributions; the most significant shift was detected at the leading edge of ELV (+73 m) and TEMP (−2.6 °C), but surprisingly there was no beech movement identified at the trailing edge. The observed shift may be a result of the interplay between climate change, high spatial variability in microclimate, unexceptional droughts in the recent past, changes in forest use and possible limitations in the migration ability of beech and its adaptation capacity. Nasl. z nasl. zaslona. Opis vira z dne 23. 8. 2022. Bibliografija: str. 13-16.

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 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.

The long-term dynamics of silver fir in mixed silver fir-European beech forests in Slovenia was studied in three geographically dislocated study areas, i.e. Leskova dolina, Trnovo and Jelovica. In the study, archival data on forest stands for the past century were used to create the GIS database, which included data for the periods 1912-2004 for the Leskova dolina study area, 1897-2003 for the Trnovo study area, and 1899-2002 for the Jelovica study area. In the observed period, substantial changes in diameter structure of silver fir and its proportion in stand volume were recognized. In Leskova dolina and Trnovo, the silver fir population was ageing, while in Jelovica it rejuvenated. In Leskova dolina and Trnovo, the silver fir proportion in stand volume decreased in the observed period, indicating its reciprocal replacement with European beech. The analyses of regeneration and recruitment designated different future potential of silver fir in the study areas. The found dynamics of silver fir is underpinned by a complex array of influential factors, notably past forest use, the impact of large ungulates, and site conditions.