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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.

Raziskava je potekala v pragozdnem rezervatu Rajhenavski Rog, v delu Dinarskega gorstva na jugu Slovenije. Šlo je za četrto izvedbo meritev mladovja v šestih vrzelih, na vzorčnih ploskvah razporejenih v mreži 5 x 5 m. Raziskava je potrdila zmanjšanje gostote mladovja z njegovim razvojem, ob tem pa povečanje deleža bukve. Delež zastiranja tal z mladovjem se je proti pričakovanjem zmanjšal, povečalo pa se je zastiranje z ostanki odmrlih dreves in skalami. Prehajanja jelke ter javorja v višje višinske plasti ni bilo, močno pa so se zmanjšali tudi njuni gostoti v prvem višinskem razredu, kjer zdajšnja jelova znaša 0,01 m-2, javorjeva pa 0,005 m-2. Bukev ima glede na spremembo gostot po višinskih razredih normalen razvoj. Manjšanja objedenosti z višinskim razvojem mladovja ni bilo moč z gotovostjo potrditi. V raziskavi smo merili in ocenjevali tudi različne parametre dominantnega osebka vsake ploskve. Ob zadnji meritvi je delež enojne razrasti glavnega poganjka, v nasprotju s pričakovanji, upadel, narasla pa sta deleža rogovilaste in metlaste razrasti. Delež enoosne oblike razrasti dominantnega osebka je nekoliko upadel, delež plagiotropne razrasti pa precej narasel. HD razmerje dominantnih osebkov še naprej narašča. This research took place in an old-growth forest reserve, Rajhenavski Rog, located in the Dinaric Mountains in southern Slovenia. It was the fourth measurement of tree regeneration in permanent plots located in six gaps with a 5 x 5m grid used to define the plot locations. The analysis confirmed a decline in regeneration density (competitive thinning) and an increasing proportion of beech. There was also a significant decline in regeneration cover, and an increase in the cover of dead wood and rock cover, which was against our expectations. There was no recruitment of fir and sycamore maple in different regeneration height layers, and their densities in the first regeneration layer heavily decreased over the length of the study. The density of the fir is now 0,01 m-2 and the density of sycamore maple 0,005 m-2. Beech exhibited normal development considering the density changes in regeneration layers. Even though regeneration has recruited to taller height classes over time, we could not confirm that browsing decreased. We also measured and evaluated different parameters on dominant beech stems in each plot, including tree architecture. The results show that the proportion of stems with single terminal shoots (optimal architecture), contrary to our expectations, slightly declined over time, while the share of stems with plagiotropic growth and two terminal shoots rose considerably. Finally, the height-diameter ratio of the dominant stems rose continuously over time.