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Silver fir (Abies alba Mill.) is a key species in the mixed mountain forests of the Dinaric Mountain range, where is typically co-occurs with European beech (Fagus sylvatica L.) and a number of other less dominant species, including Norway spruce (Picea abies). In these forests silver fir is an ecologically and economically important species providing high quality wood and a large range of ecosystem services. Silver fir is very sensitive to particular anthropogenic stressors. For example, many studies have reported several decades of silver fir decline as a result of air pollution, as well as recruitment failures in areas with high population densities of ungulates. After the reduction of industrial air pollution, the growth and health status of fir improved, showing its resilience and recovery potential. Recently, fir has become more important in European forests, especially as a conifer tree species that, according to some research, can be a source of quality technical wood under a warmer and more drought prone climate. Spruce, which has so far been the main source of technical timber in Europe, is dying out across much of its range due to a combination of adverse environmental factors and biotic disturbance. Whether silver fir will be able to partially take over the role of spruce, however, strongly depends on silvicultural measures. These must, among other, include solutions to promote the weakest part of the development of fir stands, namely regeneration and recruitment, as follows: i) using different selection sylvicultural systems (Dauerwald), ii) substantial and prolonged reduction of ungulate populations, iii) silvicultural treatments to improve the competitive power and growth of silver fir seedlings, iv) using sowing, planting, and silver fir wildlings, and v) testing southern (Submediterranean) provenances of silver fir and its performance under climate change.

Fruits of service tree were harvested in the fall of 2018 on 10 trees in the area of Tounj. The aim of the study was to determine the age of the trees and the environmental factors on seed germination of seed and morphology of bare root seedlings 1 + 0. To determine the age of the trees and the dendroecological analyzes, increment cores were taken with the Pressler drill bits. On each individual tree were taken two opposite increment cores on the chest height (d1.30). After the collection of the increment cores, standard processing and mechanical preparation of the samples were made. Prepared samples after processing were lens out using ATRICS system and then processed and analyzed with dendrochronological programs. The values of width of both late and early wood were measured. Chronologies of width of the tree rings are standardized using the RCS method and correlations with climate factors (air temperature and precipitation) have been made. The number of seeds in 1 gram ranged from 21 to 41 pcs, depending on the tree. Prior to stratification the seed was moistened for 24 h in distilled water at room temperature. Seed stratification at a temperature of 3°C was duration for 109 days. As a stratification medium, wet sand (ratio of seeds and sand 1: 4) was used. The sowing was done in ranks in Dunemann's bed 02.04.2019. Seeds from each tree were sown separately and quartz sand was used as a substrate for covering. In the period from 17.04. to 16.05, every week, counting the seed germination. As a counting criterion, there was a cotyledons over the surface of the substrate. The total nursery germination varied with respect to the tree and ranged from 12.27 to 59.11%. From sowing to the end of germination, regular plant care was performed in the Dunemann's bed, which included the protection of damping off of seedlings, which was performed on three occasions with Cuprablau Z, Dithane M-45 and Captan WP 50 fungicides. At the end of the vegetation, the height (cm) and the diameter of the root plant root (mm) were measured.

U ovome istraživanju donosimo pregled šteta nastalih od prirodnih nepogoda prouzrokovanih klimatskim promjenama u šumskim ekosustavima Republike Hrvatske za razdoblje od 1995. do 2018. godine. Iz arhivskih dokumenata i postojećih publikacija prikupljeni su podaci o količinama (masa posječenih stabala u m3) i godinama kada su zabilježene nepogode te analizirani prema vrstama drveća i dominantnoj vrsti nepogode. Rezultati istraživanja ukazuju da je tijekom zadnjih 25. godina ukupno direktno oštećeno gotovo 18 milijuna m3 drvne mase od čega dominiraju sušenja, ali i vjetroizvale. Najugroženije vrste drveća su hrast lužnjak, obična jela i bukva, dok je unazad 5 godina zabilježen rapidni porast sušenja poljskog jasena. Ukupna procijenjena šteta iznosi gotovo 18 milijardi kuna, a godišnji trend povećanja šteta iznosi 15, 5 milijuna kuna.

Gotovo polovica hrvatskih poplavnih šuma (67.470 ha) zastupljena je poljskim jasenom (Fraxinus angustifolia Vahl.) koji pokriva 29.748 ha riječnih bazena. Općekorisna vrijednost poplavnih šuma iznosi 6, 4 milijarde eura od čega 2, 8 milijardi eura pripada jasenovim sastojinama. Drvna zaliha šuma poljskog jasena iznosi 4, 3 milijuna m3 i veže na sebe 11, 8 milijuna tona ugljičnog dioksida djelujući kao važan element pohrane ugljika. Prirodna i umjetna obnova ovih šuma pod direktnim je utjecajem brojnih biotičkih i abiotičkih čimbenika od kojih mnogi ozbiljno ugrožavaju njihovu obnovu. Štetni kukci, patogene gljive, krupna divljač te sitni glodavci imaju značajnu ulogu u složenim procesima propadanja i sušenja jasenovih šuma. Nedavno dramatično širenja gljivične bolesti (Chalara fraxinea Kowalski) na poljskom jasenu u Europi te pojava azijskog krasnika (Agrilus planipennis Fairmaire) i povećana učestalost klimatskih promjena, zahtijevaju potrebu intenziviranja istraživanja ovog fenomena. Integriranim multidisciplinarnim pristupom, tijekom protekle tri i pol godine, predloženi istraživački projekt Hrvatske zaklade za znanost (IP_11_2013_4250) usmjeren je na nekoliko kritičnih aspekata spomenutih bioloških štetnih čimbenika koji se analiziraju u danom području i vremenu s ciljem pružanja mnoštva novih detalja o mehanizmima njihovog djelovanja. Metodološki pristup obuhvatio je sljedeće teme istraživanja: prisutnost, lokalni utjecaj i širenje bolesti poljskog jasena i test otpornosti domaćina ; značaj jasenovih defolijatora i mogućnosti upravljanja njihovim populacijama putem entomopatogenih organizama ; utjecaj sitnih glodavaca na obnovu sastojina te njihova važnost kao rezervoara uzročnika zoonoza ; negativan utjecaj krupne divljači na obnovu sastojina poljskog jasena ; te geoprostorne i vremenske analize glavnih biotskih čimbenika u određenim šumskim zajednicama.

Summary Gap regeneration in two old-growth forest reserves in Slovenia (Rajhenavski Rog) and Croatia ( C orkova Uvala) was analysed in relation to within gap light heterogeneity. Both reserves were located in the Dinaric mountain range in south-central Europe and were dominated by beech ( Fagus sylvatica L.) – silver fi r ( Abies alba Mill.) forest communities with similar growing conditions. In total, the two largest gaps (700 – 2000 m 2 ) in each reserve were included in the study ( n = 4), plus a further four gaps in Rajhenavski Rog and three in C orkova Uvala (200 – 500 m 2 ). All the gaps were ~ 10 years old and originated from one or two successive events, mostly due to a combination of fungi attack and windthrow. Consequently, all gaps had complex geometry and were covered by a well-developed regeneration layer. Each gap was mapped, followed by establishment of a N – S oriented 5 × 5 m grid within and around the area of the canopy opening. At the grid intersections 773, 1.5 × 1.5 m plots were established. On each plot, the coverage of tree regeneration and ground vegetation, seedling density in different height classes and browsing damage were recorded. In addition, the total stretched length and last growing season increment of the leading stem was measured on selected seedlings in each plot. Relative diffuse and direct radiation were estimated using digital hemispherical photographs. All plots were classifi ed into four microsites according to direct and diffuse radiation levels, and microsites were tested for differences in regeneration height and density. While there was more woody regeneration and an almost fi vefold higher (6.2 vs 1.3 m − 2 ) average total regeneration density in Rajhenavski Rog, mainly due to a high (5.5 vs 0.6 m − 2 ) density of beech, there was more ground vegetation and a higher density of silver fi r seedlings in C orkova Uvala. The within-gap regeneration patterns proved to be similar in both forest reserves and showed that 1-year-old seedlings of beech and silver fi r and small beech seedlings preferably recruit on microsites under closed canopy or close to gap edges with lower levels of direct and diffuse radiation. There was no signifi cant difference in density of large-beech seedlings among the microsites, yet height and height increment were higher on microsites receiving the highest levels of direct and diffuse radiation. Within-gap heterogeneity in light conditions appears to signifi cantly

Silver fir is the most damaged and threatened forest tree species in the Republic of Croatia, and the appearance of crown defoliation and tree dieback has been attributed to different causes. The objective of this study was to determine the relationship between crown defoliation and tree dieback of silver fir with regard to climatic and structural factors, to determine the causes of dieback (crown defoliation, wind) and the differences in the intensities of tree dieback of silver fir in a beech-fir forest, and in a fir forest with hard ferns. Data on crown defoliation and tree dieback of silver fir were collected from two permanent experimental plots in Gorski Kotar. Crown defoliation was assessed as percentages according to the ICP Forest Programme Guidelines, and dieback intensity was expressed as the percentage share of dieback and living trees. In both forest ecosystems, there was a significant increase in crown defoliation. The average defoliation time of the observed trees was higher in mixed beech-fir forests in comparison to fir forests with hard ferns. With regard to the intensity of tree dieback expressed as the number of trees, tree basal area and wood volume, the majority of dieback was found in fir forests with hard ferns. Greater tree dieback was recorded due to crown defoliation in comparison to wind breakages and uprooting. Of the climatic factors, crown defoliation was most affected by air temperature and the amount of potential evapo-transpiration. With the increase in crown defoliation, the life of the tree and its girth increase were significantly decreased. The correlation between crown defoliation and tree dieback was significant and positive, and this correlation was stronger in beech-fir forests, where it measured moderate to strong, while it was very weak in fir forests with hard ferns.

Klima je kompleksan neposredan ekološki čimbenik koji opisujemo pomoću različitih klimatskih elemenata, pojava i indeksa. Najvažniji ekološki čimbenici koji uvjetuju razvitak, sastav i raspored pojedinih oblika šumske vegetacije su klima i tlo. Šumsko drveće i ostali organizmi prilagođeni su određenim klimatskim uvjetima koji prevladavaju u njima. Međutim, klima je u stalnoj promjeni. Promjena klime općeniti je termin kojim se obuhvaćaju svi mogući oblici nepostojanosti klime. Uz prirodne klimatske oscilacije, klimatske se promjene posredno ili neposredno pripisuju ljudskim djelatnostima. Uz problem promjena klime, od klimatskih elemenata, najviše se vezuju temperatura zraka i količina oborina. Cilj istraživanja bio je utvrditi promjene najvažnijih klimatskih elemenata i indeksa na području Spačve, te procijeniti njihov potencijalni utjecaj na dio ekološke niše hrasta lužnjaka. Smanjenje ili povećanje pojedinih klimatskih elemenata i indeksa analizirani su pomoću linearnog trenda. Uspoređene su vrijednosti klimatskih elementa i indeksa referentnog niza sa razdobljem od 1991. do 2009. godine. Prognozni je model ekološke niše hrasta lužnjaka od danas do 2080. godine izrađen, s obzirom na model klimatskih promjena, pomoću logističke regresije. Na području nizinske Hrvatske utvrđena je tendencija pozitivnoj vrijednosti temperature zraka, količine oborina, evaporacije, te indeksa manjka vlage. Tendencija porasta temperature zraka i evaporacije statistički je značajna. Vrijednosti indeksa manjka vlage povećale su se, što ide u prilog aridnosti područja istraživanja. Prema ovim rezultatima, klimatske promjene u budućnosti nepovoljno će utjecati na ekološku nišu hrasta lužnjaka.

There are 13 species and subspecies of the genus Sorbus L. growing wild in the Republic of Croatia. Due to their fleshy fruit, species of the genus Sorbus L. belong to forest fruits, similar to other secondary tree species that contribute to the biological diversity of stands, serve as a suppport for the principal tree species and improve soil quality. During the autumn of 2003, trees of four species of the genus Sorbus L. (S. aria, S. aucuparia, S. domestica and S. torminalis) were recorded in different localities in the Republic of Croatia. Dendrometric data, tree coordinates, altitude and exposure were measured. The social position of each tree was assessed and the degree of yield was determined over a period of 6 years (2003 - 2008). Of the total of 77 registered trees, there were 13 whitebeams, 14 rowan trees, 13 service trees and 37 wild service trees. A good seed crop of whitebeam, service tree and wild service tree in the Republic of Croatia occurs at intervals of every four years, while that of rowan takes place at intervals of every three years. The properties of these species include sensitivity to competition and the non-existence of pure stands.

Plitvice Lakes are the oldest Croatian National Park, and in 1979 were listed on the UNESCO List of World Heritage. The basic phenomenon is the combination of waterfalls and 16 cascading lakes formed as a result of permanent biodynamic process of creation and growth of tufa. The lakes are surrounded by forest vegetation of a total area 25.000 ha under the Park's jurisdiction. Forests are very interesting and complex for phytocoenological research, primarily due to its preservation, geographical position which is characterized by intermediate forms of continental and Mediterranean, Alpine-Central European and Balkan-Illyrian vegetation, various environmental conditions and floristic composition, as well as numerous successional stages on deforested, mostly former agricultural land. Map of forest vegetation in scale 1:25.000 is made on the basis of SPOT satellite images (resolution 2.5 x 2.5 m). The field research included 424 plots (176 releves and 248 control points). Individual coordinates in the radius of 30 m for each forest community (habitat type) were set up as the learning field for supervised classification. "Maximum likelihood" method which is integrated within the program ArcMap 9.1. was used. The results of classification in raster format are simplified by using the tools of generalization and then transferred to the vector form (polygons). Some polygons are manually adjusted on the basis of detailed fieldwork and testing results of the classification. Software tools QGIS and ArcMap 9.1. were used. The final map is complemented by analysis of geomorphological factors and the use of previous geological, soil, climate and other research. On the vegetation map 30 cartographic units and 3 cartographic characters are presented. They are defined according phytocenological principles taking into account the recent situation concerning the dominant species and the manner of their foundation or domination. They are divided into 4 different groups: natural forest communities, successional stages, forest plantations and secondary forest stands of anthropogenic origin and general group with the addition of cartographic signs of dominance or significant presence of certain tree species.

U radu se analizira vitalitet, zdravstveno stanje, mehanička stabilnost i rast stabala divljeg kestena (Aesculus hippocastanum L.) na području grada Velike Gorice. Uz pomoć vizualno kontrolne metode (Visual Tree Assessment), obavljena je arborikulturna analiza biološkog (vitalitet) i mehaničkog (statičkog) stanja starih i mladih stabala. Procjena vitaliteta obavljena je na osnovi skale od 1–5 te prema Roloffovom modelu (0–3). Korelacijska analiza klimatskih čimbenika (temperature i oborina)i indeksne kronologije stabala divljeg kestena provedena je uz pomoć programa DENDROCLIM. Istraživana mlada stabala divljeg kestena imaju slične dendrometrijske varijable (promjer i visina stabla, polumjer krošnje, udaljenost stabala), dok su kod starih stabala vidljive razlike s obzirom na lokacije koje su uvjetovane različitom starošću stabala, zahvatima ovršavanja krošanja i uvjetima staništa. Prsni promjeristarih stabala statističkise značajno razlikuju s obzirom na istraživane tri lokacije. Istraživana mlada stabla divljeg kestena u parku imaju statistički značajno veći vitalitet od onih u drvoredu, što se može protumačiti boljim ekološkim uvjetima. Najbolji vitalitet pokazuju stara stabla u parku, a najlošiji u drvoredu kod željezničkog kolodvora, dok najbolji vitalitet po Roloffu imaju stabla u Zagrebačkoj ulici, a najlošiji u parku. Prema evidentiranim simptomima i greškama drva mladih stabala utvrđeno je manje postotno učešće kod stabala u parku u odnosu na drvoredna stabla. Kod starih stabala divljeg kestena najveće postotno učešće simptoma i grešaka drva zabilježeno je u Zagrebačkoj ulici i u blizini željezničkog kolodvora, dok je manji udio evidentiran kod parkovnih stabla. Vizualno kontrolnom metodom uz dodatnu provjeru rezistografom, utvrđena su dva stara stabala koje trenutno treba ukloniti zbog narušene mehaničke čvrstoće te sigurnosti ljudi i imovine. Dendrokronološkom analizom utvrđen je velik senzibilitet u radijalnom prirastu stabala (0, 08–8, 17 mm). Utvrđena je značajna pozitivna ovisnost radijalnog prirasta o prosječnim količinama oborina u proljeće, dok je limitirajući učinak utvrđen za maksimalnu temperaturu zraka u proljeće.

The assessment of poplar clone productivity, with the goal of selection of elite genotypes for diverse ecological conditions, is the main pillar of tree breeding. The significance of GEI (genotype x environment interaction) in the volume stock production is the consequence of differences among genotypes on different sites or the changes in the relative ranking of genotypes [1]. Biotope- related stress is mostly linked to the low availability of elementary plant requirements, such as water and nutrients. There are three main factors that determine a success in poplar production: well aerated soil, favourable water supply and adequate mineral nutrition [2]. In the last decade the problems in management of poplar plantations and cultures (low increment, dieback of trees, difficult reforestation) in eastern Slavonia are becoming more common. As these are concurrent with the significant changes in the regime of floods and groundwater table, it is logical to assume that these phenomena are related. The stress caused by drought is characterized by loss of water, reduced water potential and leaf turgor loss with stomatal closure, which leads to a halt photosynthesis, disruption of metabolism and ultimately to the death of plants [3]. The growth and development of fast-growing trees such as poplars is dependent on the significant water consumption – for poplar plantations about 500 mm for a vegetation season [4], significantly more than the autochtonous forest vegetation. The understanding of morphological-anatomical and physiological changes caused by the lack of water can be used as a tool in tree breeding selection [5]. Optimum nutrition of fast-growing trees – given the adequate climatic conditions, water supply and soils free from toxic substances – is the most important prerequisite for high and lasting yields [6]. One of the most important goals of poplar selection is finding the genotypes that can produce high volume stock with a lower nutrient consumption. While for cultivation on most productive and optimal sites the genotypes with high demand for nutrients and water are most interesting, but selection of genotypes with smaller requirements will benefit the efficiency of poplar cultures on less productive sites [2]. The selection of poplar genotypes with a high adaptation value (high stress tolerance and potential production) in various stand conditions is the main goal of selection of poplar clones in eastern Slavonia. The reasons of recent poor performance of poplar clones in eastern Slavonia cannot be attributed to only one factor, but to various interactions of water availability and nutrients to plants that are specific for different siites. To better determine the causes for low increment, tree dieback and problematic reforestation of poplar cultures in eastern Slavonia this research should be directed towards a more detaild determination of water availability to the roots of a larger number of poplar clones in comparison with their nutritional status, preferably through several vegetational seasons, so as to encompass the dynamics of floods, soil water table and the influence of meteorological parameters. Since 'M1' and 'S 1-8' genotypes have modest yields both in high- and low-stress environments, future research should be based on a larger number of poplar clones.

A brown bear den can be a smaller rock cavity, hollow tree cavity, root or stump excavation, hollow log, or excavation under a rock. The research was conducted in the area of Nature Park Velebit. A total of 30 dens were found and processed. Most of dens found were small rock cavities (77 %). The highest percentage of dens (40%) was situated in habitat type of dinaric beech-fir forests. Forest management is present in the most parts of denning area. The most of dens were found in the climate category area of mild/temperate mesothermal climate. The dens in the research area are not endangered in relation to the average distance from the forest road and human settlements.

Park-šume su temeljno ekološko uporište glavnoga grada Republike Hrvatske. One su rijedak primjer koji pokazuje kako prirodne šume mogu rasti u uvjetima velike urbane sredine. Zbog toga je iznimno važno u zagrebačkim park-šumama osigurati višenamjensko i progresivno potrajno gospodarenje. Ono uključuje očuvanje površine park-šuma, njihovu prirodnu obnovu te redovitu njegu s ciljevima stvaranja i oblikovanja stabilnih, vitalnih, prirodnih, raznolikih i regenerativno sposobnih sastojina koje će i u budućnosti obavljati svoju općekorisnu funkciju na dobrobit građana. Obnova park-šuma je neizbježan i neophodan postupak. Park-šume treba obnavljati prirodno, na malim površinama, oplodnim zahvatima i oplodnim zahvatima u kombinaciji s rubnim zahvatima. Postupak treba provoditi u dugom pomladnom razdoblju koje će stvarati raznodobnu strukturu, temeljem izrađenog šumskouzgojnog plana, sukladno šumskouzgojnim svojstvima hrastova kitnjaka i lužnjaka koji su glavne vrste drveća park-šuma. Umjetnu obnovu ne treba isključiti kao postupak izazvan poremećenim odnosima u staništu i šumskoj zajednici. Treba je obavljati po načelima prirodne obnove. Važan je dio procesa obnove pravodobno informiranje javnosti o potrebi, značenju i metodama stručnih radova.

Početkom zime smeđi se medvjedi povlače u teško pristupačna i mirna šumska područja radi stvaranja brloga i koćenja mladih. Po pitanju tipa brloga, medvjedi nisu osobito izbirljivi. Brlog može biti manja pećina ili šupljina u stijeni, stojećem šupljem drvetu, korijenju starih stabala i panjeva, šupljem ležećem trupcu te u iskopanom prostoru ispod stijene. Istraživanja su provedena na području Velebita. Ukupno je pronađeno 20 brloga. Većina pronađenih brloga su male špilje u stijenama. Najveći je postotak brloga bio na nadmorskoj visini od 900 do 1 100 m, istočne ekspozicije i nagiba terena većeg od 25°.

Istraživanja o prirodnom pomlađivanju i uspijevanju pomlatka dalmatinskog crnog bora u novije doba nisu u nas provođena. Cilj ovog istraživanja bio je ustanoviti utjecaj stupnja sklopa na strukturu, visinski prirast i kvalitetu mladika crnoga bora. Istraživanja su provedena u G. j. Vidova gora, Šumarija Brač, Uprava šuma podružnica Split. Pokusne plohe su postavljene krajem siječnja 2008. godine u razvojnom stadiju mladika, u različitim uvjetima osvjetljenja: a) gola površina, b) rub sastojine, c) progaljeni sklop, d) potpuni sklop. U svakom stupnju osvjetljenja postavljene su tri pokusne plohe dimenzija 2 x 4 m. Na plohama su mjerene kvantitativne i kvalitativne značajke pomlatka. S obzirom na mjerene kvantitativne parametre, najbolji rezultati postignuti su na goloj površini. Kvalitativni parametri pokazuju bolje rezultate pod zastorom. Rubovi sastojine jednaki su uvjetima progaljenog sklopa. S obzirom na dobivene rezultate proizilazi kako se ove sastojine mogu uspješno prirodno pomlađivati metodama pod zastorom krošanja starih stabala, oplodnim sječama ili rubnom sječom.

Klima je kompleksan neposredan ekološki čimbenik kojeg opisujemo pomoću različitih klimatskih elemenata, pojava i indeksa. Najvažniji ekološki čimbenici koji uvjetuju razvitak, sastav i raspored pojedinih oblika šumske vegetacije su klima i tlo. Šumski ekosustavi su prilagođeni na određene klimatske uvjete koji prevladavaju u njihovom području. Međutim klima je u stalnoj mijeni. Promjena klime je općeniti termin kojim se obuhvaćaju svi mogući oblici nepostojanosti klime. Uz problem promjena klime od klimatskih elemenata najviše su vezane temperatura zraka i količina oborine. Cilj istraživanja je bio utvrditi promjene klimatskih elemenata i indeksa na području Spačve te njihov utjecaj na ekološku nišu hrasta lužnjaka. Trendovi smanjenja ili povećanja pojedinih klimatskih elemenata i indeksa analizirani su pomoću linearnog trenda. Uspoređene su vrijednosti klimatskih elementa i indeksa referentnog niza sa razdobljem 1991-2009. Na području Spačve je utvrđen pozitivan trend temperatura zraka, količina oborina, evaporacije te deficita vlažnosti. Trendovi temperatura zraka i evaporacije su statistički značajni. Trendovi indeksa kontinentalnosti te godišnjeg i ljetnog toplinsko vlažnog indeksa su negativnog trenda na području istraživanja. Značajno povećanje srednje godišnje i ljetne temperature zraka te pojava klimatskih ekscesa značajnih za današnju promjenu klime, može izazvati stresna stanja kod vrste drveća uske ekološke valencije. Manjak oborina, uz pojavu visoke temperature zraka, slabi otpornu snagu hrasta lužnjaka jer se pojačanom transpiracijom troši velika količina vode. Promjene klimatskih elemenata i indeksa na području Spačve mogu dovesti do promjena u prostornoj razdiobi, ekološke stabilnosti i zdravstvenog stanja šumskih ekosustava hrasta lužnjaka.

Spačvanski je bazen jedinstveni šumski kompleks sastojina hrasta lužnjaka od iznimne ekološke, ekonomske i socijalne vrijednosti za stanovništvo istočne Hrvatske. Površinom od preko 40 000 ha predstavlja jednu od najvećih cjelovitih šuma hrasta lužnjaka u Europi. Vitalitet i razvoj nizinskih lužnjakovih šuma u uskoj je vezi s dinamikom oborinske, površinske i naročito podzemne vode. U današnje su vrijeme, na žalost, sve izraženije negativne posljedice klimatskih promjena, i to prije svega u hidrološkome režimu (npr. pojava ekstremno sušnih razdoblja, smanjenje i/ili redistribucija oborina tijekom godine, promjene dinamike vodostaja rijeka i dinamike podzemne vode i sl.). Jedan od najvažnijih procesa u kruženju vode koji bi mogao biti podložan utjecaju klimatskih promjena je evapotranspiracija. Evapotranspiracija je proces povratka vode u atmosferu isparavanjem s površine Zemlje i transpiracijom vegetacije. Cilj je ovoga rada prikazati mogućnosti procjene evapotranspiracije, kao i dugoročne promjene osnovnih klimatskih parametara za područje spačvanskog bazena kombiniranom uporabom globalnih klimatoloških baza podataka dostupnih na internetu i lokalno izmjerenih klimatskih parametara. U radu se za procjenu evapotranspiracije koriste podaci dobiveni spektroradiometrom MODIS (Moderate Resolution Imaging Spectroradiometer) koji se nalazi na satelitima Terra i Aqua. Iz baze podataka preuzete su prostorno definirane podloge rezolucije 1 km koje daju mjesečne iznose evapotranspiracije od siječnja 2000. do prosinca 2012. godine. Za analizu dugoročnih trendova klimatoloških parametara (temperatura zraka, oborine, potencijalna evapotranspiracija i indeks suše) izrađen je niz mjesečnih vrijednosti svakog parametra od siječnja 1800. do prosinca 2012. godine. Za izradu ovih vremenskih nizova korišteni su podaci dostupni na internetu (CRU TS 2.1 i HISTALP) koji su usklađeni s podacima izmjerenima na meteorološkoj postaji Gradište. Također je napravljena procjena mogućih smjerova klimatskih promjena za razdoblje do 2100. godine pomoću baze podataka TYN SC 2.0. Na temelju dobivenih rezultata u radu se po prvi puta donose procjene konkretnih iznosa evapotranspiracije šumskog kompleksa Spačve, kao i višegodišnja i unutar godišnja dinamika evapotranspiracije za razdoblje od 2000. do 2012. godine. Dobiveni rezultati raspravit će se u kontekstu dosadašnjih i budućih promjena osnovnih klimatskih parametara. Treba naglasiti da je učinkovito planiranje gospodarenja šumama hrasta lužnjaka u uvjetima budućih klimatskih i stanišnih promjena nezamislivo bez detaljnog poznavanja čimbenika hidrološke dinamike.

U radu se analizira vitalitet, zdravstveno stanje, mehanička stabilnost i rast drvorednih i parkovnih stabala divljeg kestena (Aesculus hippocastanum L.) koja predstavljaju jedno od tradicijskih obilježja grada Velike Gorice. Čimbenici poput ekspanzije urbanizacije, globalnih klimatskih promjena, naglih promjena urbane mikroklime, neodgovarajućih arborikulturnih mjera i prostorne valorizacije doveli su do toga da stabla divljeg kestena sve više gube svoju prvobitnu funkciju, opada im vitalitet i zdravstveno stanje, ugrožava mehanička stabilnost i estetska obilježja. Uz pomoć vizualno kontrolne metode (Visual Tree Assessment), obavljena je procjena biološkog i mehaničkog stanja 55 starih i 46 mladih stabala divljeg kestena na tri lokacije (2 drvoreda i park) na području grada Velike Gorice. Procjena vitaliteta obavljena je na osnovu skale od 1-5 te prema Roloffovom modelu (0-3). Ispitivanja s rezistografom IML-RESI F500 obavljena su u području s izraženim simptomima i greškama. Za potrebe dendroekološke analize uzeti su uzorci presslerovim svrdlom s zapadne strane debla na prsnoj visini (d1, 30). Utvrđene su statistički značajne razlike u općenitom vitalitetu između mladih stabala u drvoredu u Zagrebačkoj ulici i parku (t= -2, 79646, p=0, 008336). Analizom varijance utvrđena je statistički značajna razlika u prsnim promjerima (F=13, 836, p=0, 000015), općenitom vitalitetu (F=11, 381, p=0, 000090) i vitalitetu prema modelu Roloffa (F=19, 170, p=0, 000001) između starih stabala s obzirom na lokacije. Prema postotnom udjelu pojedinih simptoma u slučaju mladih drvorednih stabala u Zagrebačkoj ulici ističe se negativna promjena i veće oštećenje (32, 31%) te pukotine (20, 77%) dok su u slučaju starih stabala najčešći simptomi negativna promjena (28, 57%) i trulež drva (25, 71%). Kod mladih parkovnih stabala najčešći simptomi su manje oštećenje (35, 71%) i negativna promjena (28, 57%) a kod starih negativna promjena (33, 04%), veće oštećenje (25, 22%) i manje oštećenje (16, 52%). Kod starih drvorednih stabala u blizini željezničkog kolodvora najčešći simptomi su veće oštećenje (42, 28%) i negativna promjena (25, 20%). Cilj ovih istraživanja je prepoznati uzroke koji utječu na slabljenje vitaliteta, zdravstvenog stanja i mehaničke stabilnosti stabala te preporučiti određene arborikulturne zahvate koji će doprinijeti zaustavljanju propadanja stabala i povećanju njihove sigurnosti uz zadržavanje karakterističnih estetskih osobina. Uz pomoć dendroekoloških i dendrokronoloških metoda analizirat će se utjecaj osnovnih klimatskih čimbenika (temperature i oborina) i provedenih arborikulturnih zahvata na debljisnki rast stabala.

Silver fir (Abies alba Mill.) is the most important commercial coniferous species in the Republic of Croatia. It is the main tree species of selection forests in Croatia that covers an area of 200, 000 ha. However, silver fir is the most endangered forest tree species due to the effect of different unfavorable biotic and abiotic factors. The outcome of these factors is a serious tree decline. Due to such a serious decline of silver fir trees, salvage cuttings and skidding of forest wood assortments are very frequent. Timber skidding causes damage to trees and forest soil affecting adversely the diameter increment and tree value, and resulting in tree decline. This paper presents the analyses of damage caused to trees by timber skidding. The aim of this research was to determine the correlation between the surface of tree damage and crown defoliation, as well as the relation between tree damage and diameter increment. On a permanent experimental plot of 2 ha covered with commercial silver fir forests in Gorski Kotar region (northwest Dinarides), perennial data were collected about crown defoliation, diameter increment and damage to silver fir trees caused by machinery. Damaged trees had significantly higher crown defoliation than undamaged trees. Crown defoliation significantly correlated with the damage surface and number of tree damages. The correlation was positive and low (r = 0.31). Damaged trees of all diameter classes had smaller diameter increment than undamaged trees. Damage surface, as well as number of damages had no significant correlation with tree diameter increment. The average tree damage surface was 607 cm2, and the average number of damages per tree was 1.5. The highest number of damaged trees was recorded in 3a defoliation class (60 – 80 % defoliation) and in diameter class above 50 cm. The largest damage surface was recorded in 3b defoliation class (80 - 99 %) and diameter class above 50 cm. According to damage surface classes, the highest number of trees was recorded in the first damage class (< 100 cm2). The highest number of damaged trees was recorded with dominant trees according to Kraft, and the largest damage surface was recorded on codominant trees.

This paper presents the results of germination and development of spruce seeds in different pH solutions under laboratory conditions. Ten different pH concentrations were used with 4 repetitions each. Concentration values ranged from pH 1.7 to 6.7. Sulphuric acid (H2SO4) and deionized water were used to prepare the solutions. Seed germination and development were tested according to the ISTA Rules. Germination was tested in an illuminated incubator (Snijders model ECD01E, Tilburg, Netherlands). The results provided some fundamental information on seed germination in different pH solutions for spruce and fir species. In addition, very useful information was obtained that will facilitate understanding of natural regeneration, particularly in changing environmental conditions (acid rain, soil acidity, etc.). The threshold pH value for normal seed germination was 2.6. Soil pH values in Croatia range between 2.7 and 8.10, with only 0.38% of soils having pH values lower than 3. Generally, natural pH concentrations of soils are favourable for spruce seed germination.

Olive (Olea europaea L.) is one of the 17 tree species that can reach more than a 1000 years of age. The oldest Croatian olive tree, ‘Perišićeva mastrinka’ that grows in Kaštela area, is a monument to a long olive growing tradition. Unknown origin and morphological characterization results (high yield, fruit size, oil content, ect.) indicate that this tree is probably a spontaneous seedling of some unknown cultivar. The exact age of this tree is unknown, although morphological assessment (trunk and crown diameter) puts it between 1500 and 2000 years. The diameter increment is an autogenous feature of olive trees, controlled by various external factors, particularly climate. The main object of this study was to compare two methods (based on counting the number of annual tree rings) of tree age determination on seven sections made of branches removed after pruning of the monumental olive tree. The traditional method used for measuring the core increment is a destructive method and, in this case, not applicable. This method was compared to the nondestructive resistograph (IML RESI F500) method with 0, 1 mm resolution and catheter (diameter of 1 mm). The TSAPWin 4.67, ARSTAN and COFECHA softwares were used in this analysis. Preliminary results have shown that the two methods are very similar (more than 90%). The tree ring width ranged from 0, 08 to 2, 94 mm, with the average value of 0, 70 mm. Autocorrelations in tree ring series ranged from 0, 6 to 0, 7, and mean sensitivity is very low with the average of 0, 37. These results indicate the possible use of this nondestructive method in age determination of very old olive trees. However, the central part of the tree is poorly conserved, and a more precise age determination would need to include at least 10 olive trees grown in similar climate condition.

U razdoblju 2006 – 2010. godine analizirani su praktični primjeri prirodnoga pomlađivanja obične bukve na malim površinama u nas (područja uprava šuma podružnica Zagreb, Koprivnica, Karlovac, nacionalnog parka Plitvička jezera, parka prirode Žumberak – Samoborsko gorje) i izvan granica Hrvatske (Belgija, Češka, Njemačka, Slovačka, Slovenija). U ovom su radu prikazani rezultati istraživanja malopovršinskog pomlađivanja obične bukve u obliku grupa na primjeru dinarske brdske bukove šume (as. Lamio orvalae-Fagetum /Ht. 1938/ Borhidi 1963), te u obliku malih sastojina na primjeru bukove šume s dlakavim šašem (as. Carici pilosae-Fagetum Oberdorfer 1957). Istraživanje je pokazalo kako priroda u prašumskim bukovim sastojinama započinje prirodno pomlađivanje na malim površinama, u skupinama i grupama. Takav način pomlađivanja može se primijeniti u šumama posebne namjene i zaštitnim šumama jer se njime oblikuju strukturno raznolike sastojine koje će zadovoljiti općekorisne funkcije takvih šuma. Takav način pomlađivanja dobar je i za šume šumoposjednika jer omogućuju koncentraciju zahvata na manjim površinama i kontinuirano planiranje prihoda. Pomlađivanje oplodnim sječama na malim površinama u velikim kompleksima gospodarskih šuma također je moguće i poželjno. Tu se uspješno pokazalo pomlađivanje na malim površinama koje se prostiru na razini male (1 – 3 ha) i srednje (3 – 5 ha) sastojine. U usporedbi s klasičnim regularnim gospodarenjem na velikim površinama, gospodarenje na malim površinama je prirodi bliskiji i intenzivniji način gospodarenja koji traži izradbu šumskouzgojnog plana sa skicom pomladnih jezgri i smjerovima njihova proširivanja. Uzgojni radovi se izvode istodobno, ali na različitim dijelovima pomladne površine. Olakšano je izvođenje i kontrola radova, a omogućuje dugoročno i kontinuirano planiranje glavnog prihoda.

U vegetacijskom razdoblju 2010. godine proveli smo detaljna istraživanja prašume Smrčeve doline na sjevernom Velebitu. Prašumski kompleks obuhvaća oko 488 ha, dio je Nacionalnoga parka „Sjeverni Velebit“ i do sada nije znanstveno istraživan. Velik dio prašume zauzimaju sastojine obične smreke rasprostranjene u dvjema šumskim zajednicama: smrekova šuma s obrubljenim gladcem (Laserpitio krapfii-Piceetum abietis Vukelić i dr. 2010) i smrekova šuma s alpskom pljuskavicom (Hyperico grisebachii-Piceetum abietis /Bertović 1975/ Vukelić i dr. 2010). Na gornjim i srednjim padinama rasprostranjena je pretplaninska bukova šuma sa žabljakom (Ranunculo platanifoliae-Fagetum Marinček i dr. 1993). Sva tri vegetacijska tipa fitocenološki su istražena metodom ciriško-monpelješke fitocenološke škole, a snimci smrekovih sastojina prikazani su u analitičkoj tablici 1 s potrebnim općim podacima. Za kvantificiranje strukturnih parametara sastojina na pokusnim plohama svim su stablima iznad 1 cm prsnoga promjera izmjereni opseg (cm), visina (m) te je određen životni status prema metodologiji Masera i dr. (1979). Ustanovljena je količina i stupanj raspadanja mrtvoga dubećega i ležećega drveta i na temelju utvrđenih parametara i odgovarajućih kriterija zaključujemo da smrekove sastojine istraživanoga područja pripadaju kategoriji primarne prašume.

Selected production characteristics and dynamics of regeneration processes in virgin forests Dobroč (Slovakia) and Čorkova Uvala (Croatia) are analysed in this work. Despite the fact that compared virgin forests are approximately in the same elevation and the research plots were established in the same group of forest types, virgin forest Čorkova Uvala has significantly lower spruce representation, higher annual precipitation and different parent rock. Higher average volume of living trees with dbh over 8 cm was determined in virgin forest Čorkova Uvala in amount of 753.3 m3.ha-1. This production characteristic was lower in virgin forest Dobroč (686.5 m3.ha-1). The reason for higher average volume of trees over 8 cm dbh in Čorkova Uvala is significantly higher annual precipitation and more favourable texture of virgin forest with a higher proportion of optimum stage. Regarding the production ability of tree species, higher maximum heights and diameters for all tree species were recorded in virgin forest Dobroč. The average deadwood volume is higher in Čorkova Uvala (290.8 m3.ha-1) and corresponds to the living tree volume. Dynamics of the regeneration processes is different regarding the seedbed. The trees occur very rarely on the decaying deadwood in virgin forest Dobroč. Tree species regenerate on the decaying deadwood in virgin forest Čorkova Uvala with higher abundance, where Norway spruce is the dominant tree species. Despite the low surface of deadwood as the seedbed (4.14% from the total investigated plot), the number of natural regeneration individuals of all tree species on deadwood represents 71.5%. Regarding the tree species composition of the natural regeneration, there is a difference in shifting into the higher height category in case of fir. In virgin forest Čorkova Uvala, it continuously shifts into the height category over 50 cm up to dbh

U radu je opisan Laboratorij za obnovljive izvore energije na Fakultetu elektrotehnike i računarstva Sveučilišta u Zagrebu. Laboratorij predstavlja mikromrežu koja se sastoji od specijalno projektiranog vjetroagregata, elektrolizatora za proizvodnju vodika povezanog s agregatom gorivnih članaka, te mrežom fotonaposkih panela. Laboratorij ima za cilj istraživanje obnovljivih izvora energije u proizvodnji električne energije zasnovanih na energiji vjetra, vodikovoj energiji te energiji Sunca. Istraživanju u Laboratoriju naglašeno su usmjerena na povećanje efikasnosti pretvorbe energije obnovljivih izvora pomoću naprednih metoda upravljanja i estimacije.

U radu su analizirane kvalitativne i kvantitativne značajke prirodnoga pomlatka u rubnom pojasu jelovo-bukove sastojine. Istraživanje je obavljeno u Gorskom kotaru. Lokalitet istraživanja nalazi se na području šumarije Fužine, u Gospodarskoj jedinici Brloško, šumski predjel Gorica, odjel 70, uz južni prometni trak autoceste Zagreb – Rijeka, na dionici između vijadukta Bajer i tunela Tuhobić. Nadmorska visina je 770 metara, ekspozicija sjeverna, a nagib terena 10 – 25%. Sastojina u kojoj je obavljeno istraživanje pripada šumskoj zajednici jelove šume s rebračom (Blechno-Abietetum Ht. 1950), na distričnom smeđem tlu. Mjerenje ponika i pomlatka obavljeno je u četiri zone rubnoga pojasa koje predstavljaju različite uvjete sastojinskog sklopa i osvjetljenja. Unutar svake zone, na razmacima po pet metara, postavljene su četiri plohe kvadratnoga oblika, svaka površine 4 m2. Kvantitativne i kvalitativne značajke prirodnoga pomlatka na rubu istraživane sastojine se mijenjaju ovisno o sastojinskom sklopu. Najgušće je pomlađena vanjska rubna zona. U toj je zoni ustanovljen najveći broj biljaka obične jele iznad 50 cm te njezin najbolji rast u odnosu na druge zone. U svim je zonama odnos duljine vršnog i prvog lateralnog izbojka manji od jedan. Pionirske vrste drveća se pojavljuju na vanjskom dijelu rubne pomladne površine. Doznaku treba provoditi na način da se u dijelu vanjskog ruba šume doznačuju samo prelomljena, natrula, bolesna, rakasta i slična stabla. U ovom dijelu ima dovoljno svjetla, pa prekomjerna sječa može dovesti do zakorovljenja staništa. U unutarnjoj rubnoj zoni treba postupno oslobađati grupe pomlatka kako bi se omogućio njihov nesmetan razvoj i uraštanje u gornje slojeve sastojine.

Ovaj uradak predstavlja prilog proučavanju dinamike dinarskih bukovo-jelovih prašuma. Dinamiku prašumske sastojine možemo podijeliti na prostorne i vremenske promjene strukturnih karakteristika. U praktičnom smislu dinamiku prašumske sastojine možemo podijeliti na tri uzajamno povezana procesa: pomlađivanje, rast i razvoj te odumiranje. Uspjeh prirodnog pomlađivanja je od krucijalnog značenja za potrajnost i stabilnost prašumske sastojine. Glavni pokretači dinamike dinarskih bukovo-jelovih prašuma su vjetar u kombinaciji s patogenim organizmima. Njihovim uzajamnim djelovanjem nastaju progale u kojima započinje obnova prašumske sastojine. Dinarske bukovo-jelove prašume sastavljene od dvije izuzetno konkurentne vrste, koje su savršeno prilagođene nepovoljnim ekološkim uvjetima, poglavito glede svjetla. Zbog toga se pomlađivanje odvija osim u progalama i pod sklopom nadstojnih stabala. Pomladak koji se javlja pod sklopom stabala nazivamo napredni ili endogeni pomladak, za razliku od egzogenog pomlatka koji se javlja u nastalim progalama. Cjelokupnu varijabilnost dinamike prašumskih ekosustava te međusobnu interakciju između jele i bukve u različitim stadijima razvoja stabala možemo opisati pomoću distribucije broja stabala prema prsnim promjerima. Oblik distirbucije broja stabala jele na polulogaritamskoj skali pokazuje bimodalni karakter, dok je distribucija broja stabala bukve više nalik negativno eksponencijalnoj krivulji. Značajan utjecaj na oblik distribucije broja stabala ima i specifična prostorna struktura razvojnih stadija stabala. Prostorna struktura kreće se od grupimičnog prostornog rasporeda u mlađim razvojnim stadijima stabala do simetričnog prostornog rasporeda nadstojnih stabala. Svjetlo kao ekološki čimbenik nema značajan utjecaj na pojavnost bukve i jele ali uvjetuje preživljavanje većeg broja pomlatka. Grupiranje pomlatka jele i bukve rezultat je heterogenih mikrostanišnih prilika, dok je konkurencijska sposobnost jele i bukve uvjetovana tolerancijom vrste na nepovoljne ekološke čimbenike.

This paper presents the Laboratory for renewable energy sources (LARES) at the Faculty of Electrical Engineering and Computing, University of Zagreb, Croatia, with emphasis put on the laboratory wind turbine development and testing. The laboratory consists of a micro grid comprising wind turbine, hydrogen fuel cells and an array of solar panels. Wind turbine is definitely the most complex subsystem in this setup and its development was a very demanding task. Almost two years of development resulted in a realistic model of pitch controlled variable speed wind turbine that allows for investigation of various pitch and torque control concepts.

The study aimed to research the influence of altitude on dimensions, i.e. the shape of Wild Service tree fruits (Sorbus torminalis (L.) Crantz). We also wanted to test the variability of major biological characteristics of fruits and seed, the elements of seed quality and their relations. In September 2003 we gathered fruits from 24 Wild Service Trees of different ages and positions in the stand structure on three sites (Medvednica, Psunj and Južni Dilj) situated at different altitudes. The altitude of each tree was determined with the GPSmap 60CSx device, after which dendrometric measurements were carried out and fruits were collected.We measured fruit length (FL) and width (FW) and calculated their index (FL/FW). The mass of each fruit was weighed on the laboratory scales Sartorius and the number of fruits per kilo was calculated. The seeds were manually extracted from the fruits and the number of filled (sound) seeds per fruit was counted in line with the ISTA rules. In order to break the double seed dormancy we applied the stratification in accordance with the ISTA rules. For the statistical analysis of the data we used ANOVA, LSD test, correlation analysis and canonical discriminant multivariate analysis with the locality as a grouping variable. All statistical analyses were performed using STATISTICA 8.0 program package. We obtained a positive and strong correlation between fruit length and altitude (R=0.67), i.e. between fruit shape index and altitude (R=0.71), which means that the higher the altitude of the population of the Wild Service Tree in the Republic of Croatia, the longer the fruits. At higher altitudes the Wild Service Tree seed shows a larger degree of dormancy and requires somewhat longer period of stratification. The observed differences between the three studied locations might be attributed to changed climatic and soil conditions.

U radu je prezentirano aktualno stanje gospodarenja s prebornim šumama u Republici Hrvatskoj.