Application of digitalisation of crowns and method Of visualisation in a study of stand structures

U radu se iznose mogućnosti novog načina izučavanja strukture sastojina na primjeru digitalizacije krošanja i izrade digitalnog trodimenzionalnog modela sastojina (vizualizacije). Kao podloga za to, uzete su dvije naše karakterističe prirodne mješovite sastojine, sastojina hrasta lužnjaka i običnoga graba (Carpino betuli-Quercetum roboris, /Anić 1959/ emend. Rauš 1969) te sastojina bukve i jele (Omphalodo vernae-Fagetum Marinček et al. 1992). Na pokusnim plohama trajnoga karaktera sva su stabla obrojčana i kartirana, a istima su izmjereni prsni promjeri, visine stabala, dužine debala te snimane horizontalne projekcije krošanja. Projekcije krošanja zatim su digitalizirane u CAD programu MicroStation, aplikacija IRAS B, sa srednjom točnošću od 4 cm. Samo geokodiranje i izjednačenje obavljeno je Affinom transformacijom (projiciranje koordinate iz jedne ravnine-izvorni koordinatni sistem, u drugu paralelnu ravninu-izlazni koordinatni sistem) te prebacivanju rasterskog file-a u vektorski oblik, također u programu MicroStation. Na vektorskim plohama izračunate su površine bez zastora krošanja unutar područja (plohe) te površine pod krošnjama izvan područja (plohe). Zatim su datoteke transferirane u program AutoCAD 2000 dwg zbog pojednostavljenog načina prikazivanja. Projekcije krošanja upotpunjene su vertikalnim profilom (CorelDraw) sastojine koji proporcionalno prikazuje odnos osnovnih elemenata krošnje i debla. Na temelju izmjerenih dimenzija stabala na terenu i računalnim programom 3DS Max napravljen je trodimenzionalni model sastojine. Modelu je pridružena odgovarajuća tekstura krošanja, čime se dobio slikovitiji prikaz situacije. Kod izradbe modela vodilo se računa o prostornom rasporedu stabala, visinama stabala, dužinama debala, dužinama i širinama krošanja te o fenotipskim oblicima krošanja hrasta, graba, bukve i jele. U sastojini hrasta lužnjaka i običnoga graba simuliran je naplodni sijek te isti prikazan u trodimenzionalnoj naravi. Modeli omogućuju računalno praćenje i simulaciju obavljenih gospodarskih jera u sastojini i otvaraju nove mogućnosti rješavanja i upravljanja postojećim informacijama, a svoju primjenu mogu naći u aerofototaksaciji i GIS-u. Metode trodimenzionalne vizualizacije mogu poslužiti predočavanju prirodnog razvoja sastojina, vizualnoj usporedbi sastojina prije i poslije zahvata, kao i pomaku paradigme (primjera-obrasca) istraživanja u šumarstvu od promatranja cijele sastojine prema pristupu istraživanja pojedinog stabla.The paper presents the possibilities of a new method for the study of stand structures by crown digitalisation and production of a three-dimensional model of stands (visualisation). An investigation was carried out in a natural mixed stand of Peduncled oak and Common hornbeam (Carpino betulli-Quercetum roboris, /Anić 1959/ emend. Rauš 1969) and in a beech and fir stand (Omphalodo vernae-Fagetum, Marinček et al 1992). On experimental plots of permanent character all trees were marked by numbers and mapped, and d b h, tree heights and stem lengths measured and horizontal crown projections recorded. Crown projections were then digitalised in the CAD programme MicroStation, application IRAS B with mean accuracy of 4 cm. Geo-coding and functions of equation were performed by Affin transformation (coordinate projection from one plane-source coordinating system into another plane-exit coordinating system) and by transforming the raster file into vector form; also in the programme MicroStation. On the vector planes without canopy within the area (plot) and surfaces under crowns outside the area (plots), were calculated. Data were then transferred into the AutoCAD 2000 dwg programme for the purpose of simplification of presentation. Crown projections were completed by the vertical profile (Corel Draw) of the stand, which proportionally shows the relation between basic elements of the crown and stem. A three-dimensional model of the stand was made based on the measured dimensions of trees in the field and by the computer programme 3DS Max. The corresponding texture of crowns was added to the model, which resulted in a clearer presentation of the situation. During construction of the model attention was paid to the spatial distribution of trees, tree heights, stem lengths, lengths and widths of crowns and phenotypical forms of crowns of oak, hornbeam, beech and fir. Seed - cutting was simulated in the stand of Peduncled oak and Common hornbeam and shown in three-dimensional form. The models enable computer monitoring and simulation of management measures in a stand and present new possibilities for solving and using existing information, and their application can be found in aerial-photography estimation and GIS. Methods of three-dimensional visualisation can serve for the presentation of natural development of stands, visual comparison of stands before and after intervention, as well as for the change of the paradigm (example-pattern) in forestry research from whole-stand observation to investigation of an individual tre

Growth and Development Dynamics of Young Holm Oak (Quercus Ilex L.) Stands after Shelterwood Cutting in Open Forest Road Conditions

The Mediterranean forest region has been exposed to anthropogenic impacts for centuries, and the constant biotic and abiotic factors, together with increasing climate change, have hindered the proper management of forest ecosystems. This study presents the results of multiyear, systematic, specific and practical monitoring of the conversion of holm oak coppices using the principles of the shelterwood system. It also presents the growth and development dynamics of the stand on a permanent experimental plot from 1997 to 2017. The research was performed in the Eumediterranean vegetation zone of coniferous forest (Forest Management, Buzet branch, Pula Forestry Office, Magran Cuf management unit, compartment 83a). The plot has all the properties of a holm oak and manna ash forests (Orno-Quercetum ilicis H-ić/1956/1958). The basic elements of stand structure were monitored: diameter at breast height (DBH), tree height, horizontal crown projection, crown ground shading (light) and the appearance and abundance of all woody vegetation, with special emphasis on the growth and development of young generations of holm oak from seed. The paper also describes the threats limiting growth, development and survival of holm oak from seed (strong shooting tendencies of coppiced holm oak and bay laurel trees, excessive presence of shrubs). Forest management requires effective, timely and repeated tending to thin stands (already under the canopy), while also protecting young trees from wild game. The statistical method of interpolation determined the trends of stand development; trend equation with coefficient of determination (R2) is very high. This indicates the growth and development of the stand in the direction of renewal of holm oak stands. Shelterwood cutting, with regular and timely tending of young generations of trees through a seven-year regeneration period, resulted in a high quality young high forest of holm oak, the first of its kind in the broader Mediterranean area. The indigenous stands of holm oak, as the fundamental climatogenic coniferous species of the Mediterranean species, have multiple roles such as protection from erosion, resilience to biotic and abiotic factors and forest fires, tourism and landscape functions, and other general forest functions, and therefore deserve intensive and ongoing research. Holm oak stands also play a part in conserving genetic and biological diversity, the potential and persistence of forest ecosystems, improving stand structure, stability and resilience of forest ecosystems to climate change, and in the long-term increase the commercial value of forest stands in the Croatian Mediterranean

Which Douglas-Fir (Pseudotsuga menziesii (Mirb.) Franco) Provenances Provide the Best Productivity in the Hilly Area of Croatia?

Background and Purpose: Recently raised questions on adaptability of native tree species to climate changes pointed to Douglas-fir as a species suitable for rapid reforestation and increase of stand resistance. The first results on provenance research need to be confirmed in later stages of stand development, so the paper answers the following two questions: (i) are there differences in growth of 14 Douglas-fir provenances still in the fifth decade of stand development, and (ii) which provenances should be used and which omitted from further use in the hilly area of Croatia? Materials and Methods: Productivity of 14 provenances was evaluated on the basis of height, diameter at breast height and volume in the 46th year after planting. Growth dynamics was also statistically analysed using a repeated measure analysis of variance, for which purpose we partially used published data from the 2010. Results: The analysis excluded Castle Rock and Shady Cove (Oregon) provenances due to their low values of all analysed growth indicators, as well as Castle Rock, Elma and Hvidilde provenances due to their high values. Average values of tree volume ranged from 0.53 m3 (Shady Cove) to 2.05 m3 (Castle Rock), while the tallest trees belonged to Elma provenance (29.6 m). Conclusions: Different growth dynamics of provenances were confirmed for later development stage, so further monitoring is still required. Clear guidelines for the selection of provenances for practical forestry distinguish provenances from lower altitudes of the State of Washington, Denmark and Bulgaria as the most productive. Shady Cove and Salmon Arm provenances are not advised to be used in the future

Analysis of the Fire Season of 2020 in the Mediterranean Bioclimatic Zone of Croatian Adriatic

Fire season in the Mediterranean bioclimatic area is most associated with the period from June to late October. Despite this, a large number of fires occur in February and March due to the intentional burning of agricultural lands. A characteristic of the Mediterranean region is the strong adaptation of vegetation to fire, though this adaptation also depends on the frequency and intensity of fires. This frequency is shown on satellite images via MODIS. This paper provides an overview of indicators of vegetation fires in the Croatian coast and karst coastal belt in the 2020 fire season. The 2020 fire season was above average in comparison with the period 2010 to 2019, with more fires than average and more burnt area. A specificity of the 2020 season is seen in the large number of fires in February and March. Fire protection in Croatia is facilitated by the use of new remote sensing technologies, in combination with the existing surveillance and monitoring methods, and organised protection systems to prevent open fires

Potential Hazard of Open Space Fire in Black Pine Stands (Pinus nigra J.F. Arnold) in Regard to Fire Severity

Black pine (Pinus nigra J.F. Arnold) is one of the most important reforestation species for dry and rocky terrain in the sub-Mediterranean zone. Fire is an important factor in black pine stands that largely defines the distribution range of black pine and the floristic composition of its stands. Fire causes less damage during autumn or early spring when tree cones contain ripe seeds that can partially reforest burnt surfaces. Every fire is a potentially significant threat to forest habitats. There are many damages, from direct damages to wood mass and reforestation costs, to indirect ecological, edaphic, protective damages and the loss of biological diversity. The aim of prevention works in forestry is to reduce the number of fires and reduce burnt surface area per fire. Research was based on vegetation analysis performed on each experimental plot in a black pine stand. The assessment of fire severity was performed using the Canadian Forest Fire Weather Index (FWI). The assessment of the severity of fire indicates the suitability of conditions for the occurrence of forest fires, and enables sound and effective protective methods beginning with silvicultural works. The results indicate better quality stands in the higher parts of the sub-Mediterranean area. Taking into account the climatic parameter, the areas on the border with the continental climate have better habitat conditions for black pine. Also, attention should be focused on 2012 and 2015. High values (Figure 13 – 16.22, Figure 11 – 6.99, Figure 8 – 8.38, Figure 7 – 12.02 and 12.25, Figure 5 – 8.32) indicate the overlapping of extremely dry periods and extremely high summer temperatures, and probably a strong wind influence that further increases the index. Fire severity assessments indicate the suitability of conditions for the onset of fire

Structural Elements and Morphological Characteristics of Pedunculate Oak (Quercus robur L.) in Young Even-Aged Stands of Spačva Forest

Background and Purpose: Croatian Forest Research Institute and Croatian Forests Ltd., Zagreb, have in 2010 jointly proposed a scientific experiment on permanent experimental plots called “The Impact of the Intensity of Silvicultural Tending on Pedunculate Oak Dieback”. The basis for setting up experimental plots were the results of the analysis of surface structure of pedunculate oak (Quercus robur L.) stands of Spačva Forest and its projection area for the next 140 years, and the related issues of regeneration of old and tending of young stands in conditions of increasing climate change. In the future this will present a major problem for forestry practice in silvicultural operations, both in terms of workers and materials. Materials and Methods: The experiment was conducted in the area of Forest Administration Vinkovci, Forest Office Vinkovci, Management Unit Kunjevci, in three subcompartments of different age (10, 15 and 20 years) where different intensities tending operations of cleaning were conducted. A total of 20 plots were established by using the already established network of silvicultural lines and paths, while the position was recorded by a GPS device. On each plot 30 pedunculate oak trees were permanently marked (600 trees in total). Tree selection was based on spatial and phenotypic criteria. Results: The initial measurement on permanent experimental plots shows unsatisfactory number of pedunculate oak trees along with the high number of common hornbeam trees. The overall basal area has a tendency of continuous growth in relation to the age of experimental plots. The value of crown length in relation to the total height of pedunculate oak trees is 74.3% in subcompartment 32A, 53.5% in subcompartment 34 A, and 54.3% in subcompartment 38A. Trunk length, i.e. trunk purity also increases with age; in subcompartment 32A on average it amounts to 1.35 m, in subcompartment 34A to 3.28 m and in subcompartment 38A to 4.85 m. Conclusion: After conducting periodic surveys of the established plots by the year 2020 enough data should be collected whose processing, analysis and interpretation would provide guidelines for improving the future management of young pedunculate oak stands

Contribution to the knowledge of natural regeneration after fires and issues care of burnt areas in the stands of Aleppo pine (Pinus halepensis Mill.)

Rad ukazuje na problematiku prirodne obnove opožarenih površina u sastojini alepskog bora (Pinus halepensis Mill.) na trajnoj pokusnoj plohi postavljenoj u šumariji Šibenik. Tijekom petogodišnjih sukcesivnih izmjera (2001.-2005.) praćen je tijek rasta i razvoja vegetacije po vrstama, brojnosti i visinsko-starosnim klasama. Broj biljaka alepskog bora ukazuje na uspješnu, izrazito obilnu prirodnu obnovu, ali i problem izostanka autohtone vegetacije na opožarenim površinama. Izmjerenih 106.000-121.000 biljaka po ha pokazuje kako su mlade biljke alepskog bora brojnošću, visinom većom i od 2,5m prerasle izgoreni materijal i u potpunosti prekrile opožarenu površinu. Poseban dio istraživanja odnosi se na učinke radova njege i sanacije nakon požara koji je istraživan na tri trajne pokusne plohe na području šumarije Šibenik, Split i Korčula. Istraživanje ukazuje na promjenu pristupa sanacije opožarenih površina izostavljanjem nepotrebnog, mukotrpnog, ali i skupog slaganja preostalog opožarenog materijala na pruge. Tako visoko složen materijal na zraku se, u uvjetima mediteranske klime, izrazito sporo razgrađuje i dugo godina svojom masom povećava ionako stalno prisutnu opasnost od požara te narušava izgled krajolika. Preporuča se sanacija njegom i usitnjavanjem izgorenog materijala po površini motornom pilom tako da je preostali materijal što više uz tlo. Vlaga iz tla i uvjeti mikroklime mlade sastojine alepskoga bora, u kojima će se tako obrađeni materijal naći, pridonijet će bržem razvoju mikroorganizama, njegovoj razgradnji te bržoj humifikaciji. Alepski bor, kao vrsta drveća Eumediterana, ima značajnu i nezamjenjivu pionirsku ulogu u ozelenjavanju opustošenih površina, ali i u pripremi stanišnih uvjeta za dolazak autohtone vegetacije posebice hrasta crnike kao temeljne vrste ovoga područja.This paper points to problems of natural reforestation of burnt areas in the stand of Aleppo pine (Pinus halepensis Mill.) On a permanent sample plot set in the Forest Office Sibenik. Over the successive five-year survey (2001 to 2005.) Was monitored during growth and development of vegetation by type, number and height-age classes. Number of plants of Aleppo pine indicates a successful, highly abundant natural regeneration, but the problem is the lack of native vegetation in areas affected by fire. Measured 106000-121000 plants per ha shows that young plants of Aleppo pine abundance, height and 2.5 m over the burned material is grown and fully covered the burned area. A special part of the research concerns the effects of treatment and rehabilitation work after the fire was investigated at three permanent sample plots in the field of forestry Sibenik, Split and Korcula. Research indicates a change in approach to rehabilitation of the burnt areas by omitting unnecessary, tedious, and costly stacking the remaining burnt material on the track. This highly complex material in air, in the Mediterranean climate conditions, very slowly breaks down and the long years of its mass increases the already ever present danger of fire, and distorts the landscape. It is recommended that rehabilitation care and fragmentation of material combusted on the surface of a chainsaw so that the remaining material to the soil as much as possible. Moisture from the soil and microclimate conditions of young stands of Aleppo pine, which will be processed by the material found, will contribute to the rapid development of microorganisms, its faster degradation and humification. Aleppo pine, a species of Eumediterranean, has a significant and irreplaceable pioneering role in greening the devastated area, but also in terms of site preparation for the arrival of indigenous vegetation, especially the oak as the basic types of this area

Structure and Dynamics of the Harvest of Dead and Declining Trees of Pedunculate Oak in the Stands of Spačva Forest from 1996 to 2006

Iz dosadašnjih istraživanja, kao i iz opažanja šumarskih stru čnjaka u praksi, mogu se iščitati dvije glavne opće prihvaćene značajke veza ne uz sušenje lužnjaka s obzirom na starost sastojine i šumsku zajednicu: (1) srednjodobne, starije i stare sastojine najpodložnije su sušenju stabala hrasta lužnjaka i (2) najveći intenziteti sušenja događaju se u šumskim zajednicama hrasta lužnjaka u nizi. U ovome su radu navedene dvije pretpostavke ispitane za sastojine hrasta lužnjaka od prvoga do šetog dobnog razreda na području Spačvanskoga bazena analizom evidencije o dinamici i strukturi sječe suhih i odumirućih (3B) stabala tijekom razdoblja od 11 godina (1996. do 2006. godine). Analiza je obavljena na temelju dostupnih podataka koji se prikupljaju ti jekom redovitoga gospodarenja u “Hrvatskim šumama” d.o.o. i pohranjuju u bazu podataka HS Fond. Iz preuzetih podataka izdvojeno je 962 odsjeka ukup ne površine 20 671 ha, koji su podijeljeni u tri grupe prema fitocenološ koj pripadnosti. U odabranim je odsjecima tijekom promatranoga razdoblja ukupno posje čeno 850 835 m3hrasta lužnjaka, od čega se 58 % (492 583 m3) odnosilo na suha i odumiruća stabla. U više od 69 % odsjeka zahvati pridobivanja drva obavljani su 3 i više puta, a u 20 % odsjeka praktički svake druge godine (pet ulazaka). S obzirom na starost sastojine, intenzitet sječe suhih i odumirućih stabala naglo raste nakon ulaska u peti dobni razred, odnosno nakon starosti sasto jine od 80 godina. Međutim, daljnom je analizom ustanovljeno da postoji izra zito velika varijabilnost u intenzitetu sječe suhih i odumirućih stabala unutar istoga dobnog razreda. Dakle, ne može se donijeti generalni zaključak kada se govori o ulozi starosti sastojine u procesu sušenja lužnjaka, jer starost sasto jine vjerojatno samo pojačava ostale negativne čimbenike u onim sastojinama u kojima su ti čimbenici već prisutni. Gledajući vrijednosti ukupno posječenoga obujma suhih i odumirućih sta bala tijekom promatranoga razdoblja (m3/ha) nisu ustanovljene statistički značajne razlike među odsjecima tri biljne zajednice. Razlike su ipak potvr đene u dinamici tijekom promatranoga razdoblja. U tom je smislu potvrđena pretpostavka da su sastojine u nizi sa rastavljenim šašem nestabilnije od ostale dvije zajednice, jer je u njima zabilježen i najveći (7,1 % 1998. godine), ali također i najmanji (1,8 % 2000. godine) prosječni godišnji intenzitet, iska zan kao postotak od drvne zalihe hrasta u odsjeku. Isto tako posljedice koje sušenje ostavlja u sastojinama u nizi s obzirom na izostanak podstojne etaže različite su u odnosu na sastojine na gredi i zahtijevaju daljnje detaljne istra živačke napore kako bi ih se na odgovarajući način kvanitificiralo. Prostorno definirana baza podataka za lužnjakove sastojine Spačvanskoga bazena koja je nastala kao rezultat ovoga rada, nastavit će se nadopunja vati podacima i u idućim godinama. Povezivanje s drugim bazama podataka, pri mjerice s rezultatima motrenja razina podzemne vode s mreže piezometarskih postaja, omogućit će složenije i detaljnije prostorno-vremenske analize tren dova sušenja hrasta lužnjaka. Zaključci temeljeni na rezultatima ovoga istraži­vanja odnose se na značajke sušenja u lužnjakovim sastojinama Spačvanskoga bazena i potrebno ih je daljnjom primjenom ove ili slične metodologije provje riti u ostalim većim šumskim kompleksima hrasta lužnjaka u Hrvatskoj.From the literature sources and observations from the field forestry experts, two major assumptions regarding the relationship between the pedunculate oak dieback and the stand´s age and phytocoenological community emerge: (1) middle-aged, older and old stands are most susceptible to oak dieback and decline, and (2)highest intensity of oak dieback and decline occurs in the stands of pedunculate oak in microtopographically lowest positions – microdepressions. In the current con tribution, we investigate two afforementioned statements in the pedunculate oak stands from first to sixth age class in the Spačva forest complex. As an indicator of the susceptibility of the stands to oak dieback and decline we used dynamics and struc ture of the harvest of the dead and declining oaks in the period of 11 years (1996– 2006). Analysis is based on the available data regularily gathered during the forest management in the “Hrvatske šume” Ltd., and archived in the database HS Fond. From the acquired data, total of 962 subcompartments with total area of 20 671 ha were selected according to the set of criteria for the further analysis, and divided into three groups according to phytocoenolgical association (Table 2 and Table 3). In the selected subcompartments during the monitoring period in total 850 835 m3of pedunculate oak was harvested, out of which 58 % (492 583 m3) were dead and declining trees (Figure 9 and Figure 10). In more than 69 % of the subcompart ments, harvest events were recorded three and more times, and in the 20 % almost every second year (five harvesting events) (Figure 8). With regard to stand age, intensity of the harvest of the dead and declining oaks increases steeply after the stand age of 80 years (Figure 11). However, further ana lysis showed great variability of the intensity within the same age class (Figure 12). Thus, it is impossible to arrive at the general conlcusion about the role of the stand age in the proces of oak decline, because stand age most likely only amplifies nega tive factors already present in the stand. There were no statisticaly significant differences in the total intensity of the har vest of dead and declining oaks (m3/ha) during the monitoring period between the stands of the different phytocoenological communities (Figure 14; Kruskal-Wallis test, n=891; H=3,825; p>0,05). Difference is more prouounced with regard to dy namics of harvesting intensity. In that sense it is confirmed that stands in the micro depresions are more unstable compared to the stands of the other two forest communities with highest (7,1 % in 1998) but also the lowest (1.8 % in 2000) recor ded average yearly intensity of oak growing stock harvested trough dead and decli ning trees (Figure 13). Moreover, the consequences of the harvest of the dead and declining trees are more severe given the lack of the understory in the stands in the lowest microtopographical positions. Further research is needed to properly quan tify those differences. Spatial database of the pedunculate oak stands in the Spačva forest that emerged as one of the results in this research will be continuously updated in the following years. Interconnection of this database with other spatialy explicit databases, e.g. measurements of groundwater levels, will enable more complex and in-depth spatio temporal analysis of oak decline and dieback. Conclusions based on the results of this research relate to the pedunculate oak stands in the Spačva forest, and require verifi cation for other larger oak complexes in Croatia with further application of the met hodology outlined in this contribution

Natural regeneration of pedunculate oak stands of wet type in disturbed condition of Pokupsko basin

U radu su prikazani rezultati istraživanja prirodne obnove sastojina hrasta lužnjaka vlažnog tipa narušenih stojbinskih uvjeta. Istraživanja se temelje na dvjema razinama, postavljanjem terenskog pokusa čepovanjem te u sastojini na trima pokusnim plohama. U svrhu istraživanja sanacije oštećenih degradiranih sastojina, koje je srneća divljač višekratno obgrizala, krajem ožujka 1992. godine, osnovan je pokus primjenom čepovanja u mladoj, 6-godišnjoj sastojini hrasta lužnjaka i običnoga graba. Tijekom višegodišnjeg motrenja, s osam sukcesivnih izmjera (1991.-1998.) te izmjere 2005. godini, pra}en je visinski razvoj mladog naraštaja. Izmjere visina prvih četiriju godina načinjene su metalnim metrom s libelom, a sljedeće teleskopskom letvom. Tijekom 14-godišnjeg praćenja, od osnutka pokusa do 2005. godine, prirodno je odumrlo (bez njege) 69% promatranih stabalaca hrasta lužnjaka. Broj jedinki hrasta lužnjaka je od početnih 1,68 po m2, godine 2005. iznosio 0,46 stabalaca po m2. Poradi praćenja utjecaja biotičkih i abiotičkih čimbenika na prirodnu obnovu hrasta lužnjaka osnovane su tri trajne pokusne plohe u prirodnoj sastojini hrasta lužnjaka i velike žutilovke s drhtavim šašem (Genisto elatae-Quercetum roboris caricetosum brizoides Horv. 1938.). Pokus je praćen u vrijeme izvođenja oplodnih sječa. Radi praćenja obnove i razvoja mladog naraštaja, na rubovima te sredinom podplohe, postavljene su tri "pruge" 60 x 2m. Na prugama su ponavljane izmjere svega drvenastog raslinja svrstanog u sedam visinskih razreda. Na plohi 2 od nedostatnih 20.972 stabalaca 1998. godine, ostalo je 2000. godine tek 2.944 (14%) uglavnom suhovrhih hrastovih stabalaca, dok je ploha 3 bila bez pomlatka. Nakon dobrog uroda `ira 2000. godine, sljede}e godine na plohi 2 izmjereno je 76.333, a na plohi 3, 34.333 jednogodišnjih stabalaca hrasta lužnjaka. Nakon dvije godine (2003) na plohi 2 preživjelo je 17%, a na plohi 3 samo 6% uglavnom suhovrhog i nekvalitetnog mla|eg pomlatka lu`njaka. Praćenjem tijeka pojavnosti i razvoja mladog nara{taja hrasta lu`njaka od 1998. do 2003. godine, razvidno je kako bez vi{ekratne njege i zaštite pomlatka nije moguća prirodna obnova sastojina narušenih stojbinskih uvjeta.The paper presents the results of investigation on natural reforestation of moist type Pedunculate oak stands in disrupted stand conditions. Investigations are based on two levels, establishment of a field experiment artificial browsing and in a stand on three experimental plots. For the purpose of investigating the re-establishment of damaged-degraded stands, caused by the repeated browsing of roe-deer game, at the end of March 1992, an experiment was set up by artificial browsing in a young, six year old stand of Pedunculate oak and Common hornbeam. During several years of monitoring with eight successive measurements (1991-1998) and measurement in 2005, the height development of young growth was monitored. Measurement of heights during the first four years was performed with a metal metre and a spirit level, and the following years with a telescopic lath (surveyor\u27s pole). During 14 years of monitoring, from the establishment of the experiment up until 2005, 69% of the monitored Pedunculate oak young trees died naturally (without tending). The number of Pedunculate oak plants, starting with 1.68 per m2 in 2005 amounted to 0.46 young trees per m2. For the purpose of monitoring the influence of biotic and abiotic factors on the natural reforestation of Pedunculate oak, three permanent plots were established in a natural stand of Pedunculate oak and Green Weed (Genisto elatae- Quercetum roboris caricetosum brizoides Horv. 1938). Monitoring of the experiment occurred at the time of seed cuttings. In order to monitor the reestablishment and development of young growth on the edges and in the middle of the sub-plot, three \u27strips\u27 6o x 2 m were laid out. Measurements of all woody plants were repeated on the strips, divided into seven height classes. On Plot 2 of the 20 972 young trees in 1998, only 2 944 (14%) remained in 2000; mainly top-dry oak young trees, while Plot 3 was without seedlings. Following a good acorn crop in 2000, the following year on Plot 2 76 333 were measured, and on Plot 3 34 333 one-year old young trees of Pedunculate oak. After two years (2003) 17% survived on Plot 2, and on Plot 3 only 6%, mainly top-dry and poor quality new growth of Pedunculate oak seedlings. By monitoring the course of appearance and development of Pedunculate oak young growth from 1998 to 2003 it is evident that, without repeated tending and protection of seedling plants, the natural re-establishment of stands in disrupted stand conditions, is impossible

Natural regeneration of pedunculate oak stands of wet type in disturbed condition of Pokupsko basin

U radu su prikazani rezultati istraživanja prirodne obnove sastojina hrasta lužnjaka vlažnog tipa narušenih stojbinskih uvjeta. Istraživanja se temelje na dvjema razinama, postavljanjem terenskog pokusa čepovanjem te u sastojini na trima pokusnim plohama. U svrhu istraživanja sanacije oštećenih degradiranih sastojina, koje je srneća divljač višekratno obgrizala, krajem ožujka 1992. godine, osnovan je pokus primjenom čepovanja u mladoj, 6-godišnjoj sastojini hrasta lužnjaka i običnoga graba. Tijekom višegodišnjeg motrenja, s osam sukcesivnih izmjera (1991.-1998.) te izmjere 2005. godini, pra}en je visinski razvoj mladog naraštaja. Izmjere visina prvih četiriju godina načinjene su metalnim metrom s libelom, a sljedeće teleskopskom letvom. Tijekom 14-godišnjeg praćenja, od osnutka pokusa do 2005. godine, prirodno je odumrlo (bez njege) 69% promatranih stabalaca hrasta lužnjaka. Broj jedinki hrasta lužnjaka je od početnih 1,68 po m2, godine 2005. iznosio 0,46 stabalaca po m2. Poradi praćenja utjecaja biotičkih i abiotičkih čimbenika na prirodnu obnovu hrasta lužnjaka osnovane su tri trajne pokusne plohe u prirodnoj sastojini hrasta lužnjaka i velike žutilovke s drhtavim šašem (Genisto elatae-Quercetum roboris caricetosum brizoides Horv. 1938.). Pokus je praćen u vrijeme izvođenja oplodnih sječa. Radi praćenja obnove i razvoja mladog naraštaja, na rubovima te sredinom podplohe, postavljene su tri "pruge" 60 x 2m. Na prugama su ponavljane izmjere svega drvenastog raslinja svrstanog u sedam visinskih razreda. Na plohi 2 od nedostatnih 20.972 stabalaca 1998. godine, ostalo je 2000. godine tek 2.944 (14%) uglavnom suhovrhih hrastovih stabalaca, dok je ploha 3 bila bez pomlatka. Nakon dobrog uroda `ira 2000. godine, sljede}e godine na plohi 2 izmjereno je 76.333, a na plohi 3, 34.333 jednogodišnjih stabalaca hrasta lužnjaka. Nakon dvije godine (2003) na plohi 2 preživjelo je 17%, a na plohi 3 samo 6% uglavnom suhovrhog i nekvalitetnog mla|eg pomlatka lu`njaka. Praćenjem tijeka pojavnosti i razvoja mladog nara{taja hrasta lu`njaka od 1998. do 2003. godine, razvidno je kako bez vi{ekratne njege i zaštite pomlatka nije moguća prirodna obnova sastojina narušenih stojbinskih uvjeta.The paper presents the results of investigation on natural reforestation of moist type Pedunculate oak stands in disrupted stand conditions. Investigations are based on two levels, establishment of a field experiment artificial browsing and in a stand on three experimental plots. For the purpose of investigating the re-establishment of damaged-degraded stands, caused by the repeated browsing of roe-deer game, at the end of March 1992, an experiment was set up by artificial browsing in a young, six year old stand of Pedunculate oak and Common hornbeam. During several years of monitoring with eight successive measurements (1991-1998) and measurement in 2005, the height development of young growth was monitored. Measurement of heights during the first four years was performed with a metal metre and a spirit level, and the following years with a telescopic lath (surveyor\u27s pole). During 14 years of monitoring, from the establishment of the experiment up until 2005, 69% of the monitored Pedunculate oak young trees died naturally (without tending). The number of Pedunculate oak plants, starting with 1.68 per m2 in 2005 amounted to 0.46 young trees per m2. For the purpose of monitoring the influence of biotic and abiotic factors on the natural reforestation of Pedunculate oak, three permanent plots were established in a natural stand of Pedunculate oak and Green Weed (Genisto elatae- Quercetum roboris caricetosum brizoides Horv. 1938). Monitoring of the experiment occurred at the time of seed cuttings. In order to monitor the reestablishment and development of young growth on the edges and in the middle of the sub-plot, three \u27strips\u27 6o x 2 m were laid out. Measurements of all woody plants were repeated on the strips, divided into seven height classes. On Plot 2 of the 20 972 young trees in 1998, only 2 944 (14%) remained in 2000; mainly top-dry oak young trees, while Plot 3 was without seedlings. Following a good acorn crop in 2000, the following year on Plot 2 76 333 were measured, and on Plot 3 34 333 one-year old young trees of Pedunculate oak. After two years (2003) 17% survived on Plot 2, and on Plot 3 only 6%, mainly top-dry and poor quality new growth of Pedunculate oak seedlings. By monitoring the course of appearance and development of Pedunculate oak young growth from 1998 to 2003 it is evident that, without repeated tending and protection of seedling plants, the natural re-establishment of stands in disrupted stand conditions, is impossible