Development of the initial phase after wind throw in the virgin forest remnant Ravna gora

Zaradi vetroloma je leta 1983 v pragozdnem ostanku Ravna gora na Gorjancih na bukovem rastišču (Cardamini savensi-Fagetum) nastala 5,17 ha velika vrzel. Dejstvo, da je izsledkov o pomlajevanju po velikopovršinskih motnjah v pragozdovih malo, nas je vodilo k temu, da smo leta 2000 analizirali stanje indinamiko pomlajevanja vrzeli. Na treh različnih delih vrzeli smo postavili 15 raziskovalnih ploskev z dimenzijami 15 x 15 metrov, znotraj katerih smo analizirali zmes, razrast dreves, sestojno stanje po IUFRO klasifikaciji, pomladek in grobe lesne ostanke. Posebej nas je zanimalo razmerje med bukvijo (Fagus sylvatica L.) in gorskim javorjem (Acer pseudoplatanus L.). Slednjega je največ na sredini vrzeli. Pod sestojem, ki je zapolnil vrzel, je razvit pomladek bukve in javorja, ki je najgostejši na spodnjem (severnem) delu vrzeli. V pomladku prevladuje bukev. Ugotovili smo, da so bile razmere, ki so se izoblikovale po vetrolomu, bistveno drugačne od tipičnega goloseka. Predstavili smo tudi uporabne izsledke za gospodarjenje v gozdovih na podobnihrastiščih.Special attention is given to the gap, which was created in the virgin forest remnant Ravna gora in 1983 by wind throw. The gap in the optimal phase of almost pure beech and on beech site (Cardamini savensi-Fagetum) was 5.17 ha large. In 2000, owing to a lack of investigations in such conditions, we started to research the development patterns of natural regeneration within the gap. 15 sample plots (15 x 15 m) in three different positions within the gap were established. We analysed tree species mixture, architecture, stand structure according to IUFRO classification, advanced regeneration density andcoarse woody debris.The reserach concentrated in particular on the variability of beech (Fagus sylvatica L.) and sycamore (Acer pseudoplatanus L.) mixture in regard to theposition within the gap. It was found out that sycamore was more abundant than beech in the center of the gap. The advanced regeneration density of beech was much higher than sycamore\u27s, and both species were more abundant in the northern part of the gap. The results suggest that the ecological conditions after the wind throw were different when compared to a clear-cut area of similar size. Useful results for managed forests on similar sites are also presented

Natural regeneration ecology of a secondary altimontane spruce forests at Jelendol

Pomlajevanje visokogorskih smrekovih gozdov v Jelendolu je oteženo zaradi spleta dejavnikov. Jeseni leta 2003 smo v veliki vrzeli, malih vrzelih in pod sklenjenim sestojem na mreži 5 x 5 m postavili skupaj 227 ploskvic velikosti 1,5 x 1,5 m z namenom ugotoviti splošne pomladitvene razmere in glavne zaviralne dejavnike pomlajevanja. Na ploskvicah smo zbrali podatke o ekološkihrazmerah (relief, lega, nagib, globina tal, sestava površja, direktnoin difuzno sončno sevanje), vrsti in pokrovnosti pritalne vegetacije ter vrstah, gostoti, višinah in priraščanju mladja. Asimetrija v osvetljenostije vidna tako v smeri N-S kot E-W. Glede na porazdelitev direktnein difuzne svetlobe smo ploskvice razdelili na štiri skupine. Smreka je dobro pomlajena (28.605 na ha), zlasti izrazit je rob velike vrzeli, vendargostota mladja ni značilno odvisna od svetlobe. Nasprotno pa pomanjkanjesvetlobe onemogoča nadaljnji razvoj v sestoju in v malih vrzelih. Rezultati so pokazali, da svetlobne razmere na 1.500 m n.v. niso edini dejavnik, ki vpliva na uspešnost pomlajevanja. Velik pomen imajo še zlasti lesni ostanki, medtem ko je vpliv zeliščne plasti (prevladujeta Festuca altissima All. in Calamagrostis arundinacea (L.) Roth.) in globine tal negativen. Največji problem je še vedno objedanje.Natural regeneration of altimontane spruce forests at Jelendol is retarded dueto many factors. In autumn 2003, gaps of different size and parts of the surrounding stand were covered with a 5 x 5 grid m to define sampling plots. Atotal of 227 plots with 1,5 x 1,5 m in size were installed to analyse generalregeneration conditions and inhibitors. The following ecological parameters were estimated on each plot: micro relief, inclination, soil depth,ground cover, direct and diffuse solar radiation. Woody regeneration (density, height, height increment) and ground vegetation were recorded at each plot. Considering that N-S and E-W radiation asymmetry was explicit, the distribution of direct and diffuse radiation was divided into four groups among the plots. Spruce regeneration (28.,605 per ha) was mainly found at the edge of the large gap, though total regeneration density and radiation were not correlated. However, in both the stand and the small gaps, the lack of radiation hindered further development. This study showed that light conditions were not the only factors affecting the regeneration success at an altitude of 1,500 m. The presence of woody debris was important, while the influence of the herb layer (predominant species were Festuca altissima All. and Calamagrostis arundinacea (L.) Roth.) and soil depth proved to be negative. The impact of browsing, however, remained the main problem

Assessing the forest\u27s protective effect against avalanches : the case of Russian road below Vršič

Cesto na Vršič ogrožajo snežni plazovi, gozdovi nad njo pa opravljajo zaščitno in varovalno funkcijo pred njimi. Analizirali smo potencialno ogroženost dela ceste in gozda nad njo, opravili presojo zaščitne funkcije gozda pred snežnimi plazovi ter določili smernice in ukrepe za nadaljnji razvoj gozda in krepitev njegovega varovalnega učinka. Na objekt raziskave smo postavili mrežo 21 raziskovalnih ploskev. Po modificirani metodi NaiS (Frehner in sod., 2005) smo izločili in opisali sestoje ter primerjali njihovo dejansko stanje s ciljnim, ki zagotavlja zaščito pred snežnimi plazovi. Glede na naklon in pokritost z gozdom smo naredili karto, ki kaže najbolj ogrožena območja pred snežnimi plazovi. Ugotovili smo, da noben sestoj ne zagotavlja popolne in trajne zaščitne funkcije. Največji problem sta pomlajevanje in zagotavljanje raznomerne strukture sestojev. Najpomembnejše smernice za nadaljnji razvoj gozda so pospeševanje raznomerne in raznodobne strukture, zagotavljanje pomladka, vzgoja čim večjega števila nosilcev stabilnosti ter zagotavljanje dobre vitalnosti in zadostne gostote dreves.The road leading to the Vršič Pass is threatened by snow avalanches, and the forests above it are performing a protective function against them. We analysed potential hazard to the road and forests above it from snow avalanches, and evaluated the protective function of the forest. We defined guidelines and measures for further development of the forest to enhance its protective effect, and evaluated the actual spatial distribution of formalized protective function area of the forest within management plans. We set a network of 21 research sample plots. Using the modified method NaiS (Frehner et al., 2005), we defined the stand boundaries, analysed them and compared the actual state of the stands to the target situation. With regard to the slope and forest cover, we made a map of the sections most prone to formation of snow avalanches. We concluded that none of the stands provided complete and permanent protective function against snow avalanches. The greatest problems lay in poor regeneration and lack of unevenaged stand structure. The most important guidelines for the future development of the forest are favouring heterogeneous stand structure and regeneration, safeguarding good stability and vitality of the trees and providing for their sufficient density

Assessing the forest's protective effect against avalanches : the case of Russian road below Vršič

Cesto na Vršič ogrožajo snežni plazovi, gozdovi nad njo pa opravljajo zaščitno in varovalno funkcijo pred njimi. Analizirali smo potencialno ogroženost dela ceste in gozda nad njo, opravili presojo zaščitne funkcije gozda pred snežnimi plazovi ter določili smernice in ukrepe za nadaljnji razvoj gozda in krepitev njegovega varovalnega učinka. Na objekt raziskave smo postavili mrežo 21 raziskovalnih ploskev. Po modificirani metodi NaiS (Frehner in sod., 2005) smo izločili in opisali sestoje ter primerjali njihovo dejansko stanje s ciljnim, ki zagotavlja zaščito pred snežnimi plazovi. Glede na naklon in pokritost z gozdom smo naredili karto, ki kaže najbolj ogrožena območja pred snežnimi plazovi. Ugotovili smo, da noben sestoj ne zagotavlja popolne in trajne zaščitne funkcije. Največji problem sta pomlajevanje in zagotavljanje raznomerne strukture sestojev. Najpomembnejše smernice za nadaljnji razvoj gozda so pospeševanje raznomerne in raznodobne strukture, zagotavljanje pomladka, vzgoja čim večjega števila nosilcev stabilnosti ter zagotavljanje dobre vitalnosti in zadostne gostote dreves

Coexistence of silver fir and beech in the Dinaric Alps : implications for conservation and management of silver fir

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 gaps2) stand response to intermediate wind disturbance in the old-growth silver fir-beech Perućica forest3) long-term changes in tree species composition of old-growth forests in South East Europeand 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

Odziv crne johe (Alnus glutinosa (L.) Gaertn.) na različite intenzitete selektivne prorjede: pedesetgodišnja istraživanja u sjeveroistočnoj Sloveniji

Pure black alder stands are specific and require adapted silvicultural models. To determine the best intensity of selective thinning in such stands, research plots were established in Polanski Log in 1967. Three thinning intensities were selected: control, moderate and high. These stands are presently in a mature phase. In 1967, 1973, 1979, 1983, 1993, 1998 and 2018 diameter at breast height was measured and social status, vitality, tendency, silvicultural role, crown length and overall quality were estimated. The differences in black alder responses to thinning intensities were analysed and the results were compared with recommendations for selective high thinning and newer crop tree situational thinning models. Diameter increments were lower than expected regardless of thinning intensity. In moderately thinned plots and control plots diameter increment was the same (0.33 cm/year); high intensity thinning plots showed higher increment (0.37 cm/year). Dominant trees had slightly higher increment regardless of thinning model. Compared to thinning models with a lower number of crop trees, density and basal area of studied stands were significantly higher and diameter increments lower. We attribute the small diameter increments and small differences among thinning models to insufficient intensity and partially to inconsistent thinning. The results indicate that thinning must be of higher intensity and the largest-diameter trees which display the best vigour, quality, tendency, and which have well formed, long crowns, must be promoted from the beginning.Područje poplavnih šuma crne johe (Alnus glutinosa (L.) Gaertn.) u Sloveniji čini samo 0,4 % (približno 4708 ha) ukupne površine šumskog zemljišta (Čater i sur., 2001.). Veći kompleks takvih sastojina u Sloveniji su Črni i Polanski Log, a istraživanje je provedeno na području potonjeg (slika 1). Kako čiste sastojine johe odlikuju brojne specifičnosti, potrebno im je prilagoditi šumskouzgojne postupke. Da bi se utvrdio odgovarajući intenzitet prorjede takvih sastojina, 1967. godine u Polanskom Logu postavljene su pokusne plohe. Od tada do 2018. godine na plohama je izvršeno pet do sedam mjerenja. Sva stabla na plohama su bila obrojčana. Izvršeno je mjerenje prsnih promjera i procjena sljedećih elemenata na stablima: pripadnost etaži, vitalnost, uzgojna perspektiva, uzgojna uloga, duljina krošnje i kvaliteta (tablica 3). Svaka ploha bila je podijeljena u tri polja (40 x 50 m) s različitim metodama rada: bez intervencije, umjereno i intenzivno prorjeđivanje. Uzgojni postupci koji su poduzeti tijekom praćenja pokusa prikazani su u tablici 2. Danas su te sastojine u zreloj fazi razvoja, stoga smo u ovom radu analizirali reakcije crne johe na različite intenzitete prorjeđivanja i dobivene rezultate usporedili s preporukama autora tradicionalnih uzgojnih modela i modela koji se temelje na situacijskoj njezi šuma.Ustanovili smo da se na plohama s intenzivnim prorjeđivanjem gustoća sastojine koja je u dobi između 50 i 70 godina i na kraju je ophodnje kreće od 295 do 690 kom/ha (slika 3), dok se na plohama bez intervencije ova vrijednost kreće u rasponu od 370 do 790 kom/ha. Drvne zalihe u istom su se razdoblju kretale u rasponu od 277 do 458 m3/ha na plohama s intenzivnim prorjeđivanjem, dok su na plohama bez intervencije bile veće, u rasponu od 309 do 516 m3/ha (slika 4). U to su se doba temeljnice nalazile u rasponu između 23 i 41 m2/ha na plohama s intenzivnim prorjeđivanjem, a na plohama bez intervencije u rasponu od 26 do čak 51 m2/ha (slika 5). Tijekom cijelog razdoblja praćenja ploha, stabla su, bez obzira na metodu rada, narasla za tri do četiri debljinska stupnja (slika 2). Na plohama s umjerenim prorjeđivanjem i onima bez intervencije, debljinski prirast stabala bio je skoro jednak (0,33 cm godišnje) (slika 6). Statistički je značajan veći debljinski prirast stabala na plohama s jako intenzivnim prorjeđivanjem (0,37 cm godišnje). Debljinski prirast dominantnih stabala bio je nešto veći, od 0,46 cm godišnje na plohama bez intervencije do 0,50 cm godišnje na plohama s jako intenzivnim prorjeđivanjem, ali statistički značajne razlike između metoda rada nisu utvrđene (slika 6). Međutim, otkrili smo da kod dominantnih stabala ne postoje statistički značajne razlike s obzirom na njihovu slojevitost, vitalnost, tendenciju, dužinu krošnje i kvalitete s obzirom na korištenu metodu rada.U usporedbi s uzgojnim modelima koji su se koristili za manji broj odabranih stabla, gustoća i temeljnica ispitivanih sastojina je znatno veća, a debljinski prirast manji. Autori tradicionalnih i modela s manjim brojem odabranih stabala zagovaraju rano prorjeđivanje takvih sastojina (tablica 1). Veće razlike nastaju u konačnom broju stabala po hektaru i u intenzitetu intervencije. Razlog malog debljinskog prirasta i razlike između metoda rada na našim plohama pripisali smo nedovoljnom intenzitetu i djelomično nedosljednoj provedbi postupka prorjeđivanja. Ipak, ukazala se potreba za intenzivnim prorjeđivanjem i pospješivanjem rasta stabala najvećeg prsnog promjera, vitalnosti i tendencije, lijepo oblikovane i duge krošnje (slika 7, slika 8)