Floodplain forests are the most rapidly disappearing ecosystem in the world, especially in temperate regions of Europe where anthropogenic influence has been pronounced throughout history. Research ...on primeval forests is crucial to further our understanding of their natural dynamics and interaction with climate but is limited by the lack of such preserved forests. The aim of this study was to investigate how a primeval floodplain forest in Southeastern Europe has responded to climate variability during the last 250 years through comparison of tree growth and climate, canopy disturbance and recruitment dynamic of two dominant tree species with different tolerances to flooding/drought. Our analysis revealed induced stress caused by several consecutive severe drought events in the 1940s, which led to a significant increase in sensitivity to increasing temperatures and decreasing river water levels. This trend is particularly pronounced in pedunculate oak. Age structure analysis revealed one larger episode of oak regeneration culminating after periods of intense growth release. Such period co-occurs with summer drought, which is part of a complex system of natural disturbances and a significant natural driver of the cyclical regeneration of primeval oak ecosystems.
Tree acoustic tomography is a widely used device supported method for tree stability assessment. In this work, the results of the three most commonly used devices for acoustic tomography of standing ...trees (ARBOTOM®, ArborSonic®, and PiCUS®) were compared on selected individuals of sessile oak in Brno, Czech Republic. According to the statistical analysis, there was a significant difference between values measured by the PiCUS® acoustic tomograph and those measured by both the ARBOTOM and ArborSonic® acoustic tomographs. Based on the measured data, velocities measured by PiCUS® were considerably lower than those recorded by the other acoustic tomographs (ARBOTOM® and ARBORSONIC®). Measured radial and tangential velocities differed from each other. In data obtained from the defective cross-sections, this difference was attenuated. Image reconstructions (tomograms) from the acoustic tomographs differed from each other. Complex shapes of defects in standing trees can significantly influence acoustic tomography results. According to the statistical analysis, there was no significant relationship between sound velocity and density, while there was a relatively strong positive correlation between sound velocity and moisture content.
The Mediterranean vegetation belt on the eastern Adriatic covers an area of nearly 15,000 km2. It is comprised of forest stands that can be divided into three vegetation zones based on the presence ...of certain plant species within each: sub-Mediterranean, eu-Mediterranean, and steno-Mediterranean. The dominant ecological factors result in the domination of specific tree species within the floral composition between these vegetation zones. The aim of this study was to collect climate data from 38 weather stations over a 30-year period to compare climate data and bioclimate properties in the area of these three vegetation zones. The results confirmed statistically significant differences between the main climatic elements and most bioclimatic indices between the vegetation zones. Cooler and more humid conditions were found in the sub-Mediterranean zone, warmer and somewhat drier conditions in the eu-Mediterranean zone, and particularly pronounced warm and dry conditions in the steno-Mediterranean zone. However, the analysis of the main components for researching climate parameters showed that the mean annual air temperature, average minimum air temperature of the coldest month of the year and continentality index, length of the dry season, and de Martonne aridity index contribute the most to the grouping of vegetation in forest stands in the Mediterranean vegetation belt of the eastern Adriatic.
Silver fir is one of the most threatened conifer species in Croatia, especially at the western edge of its spread in Croatian Dinarides, where the decline in fir trees has resulted in significant ...ecological and economic issues. The aim of this study was to determine, over an 18-year monitoring period, the relationships of silver fir crown defoliation with climatic factors and structural attributes. We further analyzed the tree retention time in a given defoliation class and transition dynamics between defoliation classes, as well as the survival/mortality of trees. Data on silver fir defoliation were analyzed in two different forest types: in pure silver fir and in mixed silver fir and common beech stands. The climatic factors, primarily vegetation period air temperature, potential evapotranspiration, and dry season water deficit, were correlated with crown defoliation. Regarding the structural attributes, in the mixed stand with predominantly smaller trees, crown defoliation increased with reduced diameter at breast height, crown diameter, social class, and crown illumination. In the pure fir stand, crown defoliation increased with reduced crown diameter, greater crown asymmetry, greater crown illumination, and on trees with a stork’s nest crown. The retention time in defoliation classes differed for research sites. Transition dynamics were different only for trees in the highest defoliation class (dead trees). At the end of the study period, silver fir mortality was higher in the pure fir stand. Increased silver fir defoliation and mortality can be expected in the future, particularly in overmature stands under prolonged drought stress. Permanent forest monitoring could ensure the high-quality data needed for adaptive management of fir stands that could positively influence the structure of these stands and, thus, improve their health status.
Background and Purpose: Narrow-leaved ash (Fraxinus angustifolia Vahl) is one of the most important tree species of lowland floodplain forests in the Republic of Croatia. Recent significant climate ...changes, reflected in extreme temperatures and long dry periods, have had a direct impact on the dynamics and levels of groundwater, as well as on the dynamics of precipitation and floodwater, which are of decisive importance for the success of narrow-leaved ash. Our study aims to determine the morphological and physiological characteristics of seedlings of narrow-leaved ash after 72 days of drought, normal watering and substrate saturation.
Materials and Methods: The experiment was established in three treatments (drought, normal watering and saturation), and each treatment included two containers or 24 seedlings. A total of 72 seedlings were replanted. After 72 days, height growth and increment, water potential, photosynthetic efficiency and the total chlorophyll content in the leaf mesophyll were measured.
Results: Seedlings from the drought treatment wilted immediately. Seedlings saturated with water up to the root collar manifested better height and diameter growth, high water potential and a lesser physiological stress response as compared to the seedlings that were watered normally.
Conclusions: Seedlings of narrow-leaved ash, which is a hygrophytic tree species, do not tolerate dry conditions and no watering. Seedlings saturated with water for 72 days showed a better morphological-physiological status than the seedlings that received normal quantities of water.
Urbana stabla i šume doprinose kvaliteti života stanovnika urbanog područja i pružaju brojne koristi. Međutim, stabla u urbanim područjima su izložena različitim abiotskim i biotskim poremećajima ...koji utječu na njihov razvoj. Gljive truležnice se ističu kao bitan uzročnik pojave loma stabla. Dijagnostički instrumenti koji mjere određena svojstva drva se koriste u arborikulturi kao dopuna vizualnoj prosudbi urbanih stabala. Zvučni tomograf je uređaj koji mjeri brzinu prolaska zvučnih valova kroz drvo u radijalnom i tangentnom smjeru kako bi se prosudile unutarnje greške drva. Cilj istraživanja je bio odrediti veličinu i položaj zdravog i trulog drva te odrediti točnost zvučnog tomografa kod deset stabala hrasta kitnjaka u Parku Maksimir u Zagrebu. Usporedili smo rezultate grafičkih prikaza zvučnog tomografa (tomograme) sa fotografijama presjeka panjeva stabala koja su posječena radi potvrde truleži drva. Trulež drva je bila vidljiva na osam od deset istraživanih stabala koji su imali simptome truleži pri vizualnom pregledu. Trulež drva je potvrđena kod sedam stabala na panjevima nakon sječe. Kod tri stabla zabilježen je početni stadij truleži drva, dok su četiri stabla imala aktivnu trulež drva i pojavu šupljina. Oblik tomograma odgovarao je fotografijama presjeka panjeva kod osam stabala, a pozicija trulog drva je odgovarala fotografijama presjeka panjeva kod devet stabala. Područje trulog drva različitih kategorija je bilo točno prepoznato na tomogramima za šest od deset istraživanih stabala. Zvučni tomograf je podcijenio površinu zdravog drva, precijenio površnu drva u početnim stadijima truleži i točno predstavio područja s aktivnom truleži drva i šupljinama.
Urban trees and forests contribute to citizens’ wellbeing and provide a wide range of benefits. Yet in the urban environment, trees are exposed to a range of abiotic and biotic factors that can impair growth. Wood decay fungi are a major cause of tree failure. Devices supported methods that measure certain wood properties are often used in addition to visual assessment of urban trees. Acoustic tomography is a device that measures the velocity of sound wave propagation through wood in the radial and tangential directions and is used to assess internal defects in trees. The aims of this study were to determine the size and position of healthy and decayed wood and to define the accuracy of acoustic tomography on ten old sessile oak trees in the Maksimir Forest Park, Zagreb. Results of acoustic tomography images (tomograms) were compared with photographs of tree cross sections after felling to confirm decay. The visual assessment indicated the presence of decay on ten trees, and this decay was visible on eight of ten tomograms. Decay was further confirmed in seven cross-sections after felling. Of these, three trees had incipient wood decay, while four had active wood decay with cavity formations. The shape of tomograms and position of decay were similar to the cross-section photographs for eight and nine trees, respectively. The area of decayed wood in different wood condition categories was correctly shown on the tomograms in comparison with the cross-section photographs in six of the trees. Acoustic tomography underestimated the area of sound wood and overestimated incipient wood decay in comparison with the actual state of cross-sections, while the area of active degraded wood and cavities was accurately represented.
The paper presents the results of the impact of ectomycorrhiza and humic acids on major morphological features of 1 year old seedlings of
Paulownia tomentosa × Paulownia fortunei
(9501) hybrids grown ...from root cuttings.
Paulownia
has many desirable properties as well as negative traits such as invasiveness. Experimental plantations were established in the spring of 2015 on a field in Zagreb. We used two different spacings (2x2 m and 4x4 m), each with two treatments and control. In the first treatment we planted seedlings grown from root cuttings inoculated with ectomycorrhizal fungi at the time of planting. For the second treatment we used the inoculated plants with the addition of soil humic acids. Seedlings were planted in flower beds with black plastic foil and a trickle irrigation system. Major morphological features of seedlings were measured at the end of the first growing season. A positive impact of the ectomycorrhizal fungi and humic acids on morphological characteristics of 1 year old seedlings
was established. For the planting distance 2x2 m we established significant differences between the seedlings treated with ectomycorrhizal fungi and seedlings treated with ectomycorrhizal fungi and humic acids compared to the control seedlings in the following variables: total seedling height, stem diameter at 10 cm from ground level, number of branches, seedling height to the first live branches and length of the longest branches. For the planting distance 4x4 m we obtained statistically significant differences between the seedlings treated with ectomycorrhizal fungi compared to the control seedlings in the following variables: stem diameter at 10 cm from ground level, the number of branches and the length of the longest branches. The application of ectomycorrhizal fungi and humic acids can increase the quality of forest plantation of paulownia. Before growing and putting paulownia seedlings on the market we should consider the fact that in Croatia there are no scientific or impact studies on the nature of several species from the genus
Paulownia
, and the risks should be assessed for each taxonomy category, even lower than the species. Such studies would give specific guidelines and plans for future plantations of paulownia.
U radu se prikazuju rezultati utjecaja ektomikorize i huminskih kiselina na važnije morfološke značajke jednogodišnjih sadnica hibrida
Paulownia tomentosa x Paulownia fortunei
(9501) uzgojenih iz korijenskih reznica. Paulovnija
ima brojna poželjna svojstva, ali i negative osobine poput invazivnosti. Pokusna plantaža je osnovana u proljeće 2015. godine na poljoprivrednom zemljištu na području grada Zagreba. Korištena su dva razmaka sadnje (2x2 m i 4x4 m), svaki s dva tretiranja i kontrolom. U prvom tretiranju sađene su sadnice uzgojene iz korijenskih reznica koje su inokulirane s ektomikoriznim gljivama u trenutku pikiranja. Drugo tretiranje bilo je s inokuliranim sadnicama uz dodatak tlu huminskih kiselina. Sadnice su posađene na gredice s crnom pvc folijom, ispod koje je postavljen sustav natapanja kap na kap. Važnije morfološke značajke sadnica su mjerene na kraju prvog vegetacijskog razdoblja. Utvrđen je pozitivan utjecaj primjene ektomikoriznih gljiva i huminskih kiselina na morfološke značajke jednogodišnjih sadnica. Kod razmaka sadnje 2x2 m su utvrđene statistički značajne razlike između sadnica tretiranih ektomikoriznim gljivama i sadnica tretiranih s ektomikoriznim gljivama i huminskim kiselinama u odnosu na kontrolne sadnice u sljedećim varijablama: ukupna visina sadnica, promjer stabljike na 10 cm od razine tla, broj grana, visina sadnica do prve žive grane i duljina najduže grane. Kod razmaka sadnje 4x4 m utvrđena je statistički značajna razlika između sadnica tretiranih ektomikoriznim gljivama u odnosu na kontrolne sadnice u sljedećim varijablama: promjer stabljike na 10 cm od razine tla, broj grana i duljina najduže grane. Primjena ektomikoriznih gljiva i huminskih kiselina može povećati kakvoću šumskih plantaža paulovnija. Kod puštanja u promet sadnica paulovnija i uzgoja istih treba se uzeti u obzir činjenica kako u Republici Hrvatskoj ne postoje znanstvena istraživanja i studije utjecaja vrsta paulovnija na prirodu, pri čemu rizik treba procjenjivati za svaku taksonomsku kategoriju, pa i nižu od vrste. Takve studije bi trebale dati konkretne smjernice i planove za buduća podizanja plantaža paulovnija.
•Multiple types of evidence yield an overview of the disturbance regime in Dinaric Mountain forests.•Variation in regime components from multiple agents results in a complex disturbance ...regime.•Intermediate severity disturbance events are characteristic of the regime.
Quantitative descriptions of natural disturbance regimes are lacking for temperate forest regions in Europe, primarily because a long history of intensive land-use has been the overriding driver of forest structure and composition across the region. The following contribution is the first attempt to comprehensively describe the natural disturbance regime of the dominant forest communities in the Dinaric Mountain range, with an emphasis on the range of natural variability of regime components for the main disturbance agents. Compared to other forest regions in Europe, the mountain range has a history of less intensive forest exploitation and provides a suitable record of natural disturbance processes. Our synthesis is based on multiple types of evidence, including meteorological information, historical documentation, evidence from old-growth remnants, and salvage logging data from National forest inventories. Taken together, the results show that no single disturbance agent dominates the regime in the dominant forest types (i.e. beech and mixed beech-fir forests), and any given agent exhibits remarkable variation in terms of severity and spatial extent both within and among individual disturbance events. Thunderstorm winds cause the most severe damage (i.e. near stand replacement), but blowdown patches are typically limited to stand-scales (e.g. 10s of ha). Ice storms and heavy snow typically cause intermediate severity damage and affect much larger areas (e.g. 100s of km2). A notable exception was the 2014 ice storm, which was nearly an order of magnitude larger and more severe than any other event recorded in the synthesis. Severe and prolonged periods of drought have occurred several times over the past century, and along with secondary insect damage (e.g. bark beetles), have caused episodes of forest decline. Overall, our synthesis indicates that on top of the background of relatively continuous gap dynamics, stand-scale intermediate severity events are an important part of the regime; these events likely have rotation periods that are less than the lifespan of a tree cohort (e.g. several centuries) and create canopy openings large enough to alter successional trajectories.
The application of frequency-resonance method (FRM) for precise log bending testing is limited by complex geometry; usually the cone with variable cross. This case study presents the relationship ...among non-destructively tested material parameters of sugar maples and the numerical analysis of effect of simplifications in FRM. Four standing stems were measured to find basic geometry parameters, 3D scanned for precise geometry description, tested by pulling test (PT) to obtain elastic parameters, and, finally, cut down to process the logs. Four logs were measured by stress wave propagation (SWP) using an acoustic tomography (AT) device to obtain longitudinal sound velocities and then evaluated by the FRM to obtain natural frequencies in bending and longitudinal vibrations. Comparison was made between the dynamic moduli of elasticity (MOE), calculated from SWP and the FRM, and the static MOE calculated from the PT. In-situ experimental evaluation was accompanied by modal analysis by finite element method (FEM) working at three levels of geometry simplification (beam model, simplified solid model, and scan-based solid model); the natural frequencies of bending and longitudinal mode shapes were analyzed. The influence of geometry precision on the resulting dynamic response of logs was found regarding comparison to the experimental values.
Opasna stabla mogu prouzročiti značajne štete ukoliko dio stabla ili cijelo stablo padne na potencijalnu 'metu'. Prosudba opasnih stabala se može napraviti vizualno ili upotrebom arborikulturnih ...instrumenata. Gljive truležnice na živim stablima uzrokuju degradacije drva čime povećavaju opasnost od loma stabla. Stabilnost stabla je uvjetovana karakteristikama stabla i staništa.Istraživanje prosudbe opasnih stabala je provedeno u urbanim šumama u okviru gospodarske jedinice Park-šume grada Zagreba, u šumskim predjelima Granešina, Tuškanac, Zelengaj i Jelenovac.Rezultati istraživanja prosudbe opasnih stabala vizualnim metodama ukazuju da je mali broj opasnih stabala u šumama grada Zagreba. Između korištenih vizualnih metoda utvrđene su razlike u rezultatima prosudbe. Korištenjem EHT metode dobije se veća ocjena opasnosti ocjena od VTA metode. Na ocjenu opasnosti VTA metodom najveći utjecaj imaju simptomi zadebljanja dok na ocjenu opasnosti EHT metodom najveći utjecaj imaju greške mrtve grane u krošnji i ograničena površina korijena.VINKO PAULIĆ: Prosudba opasnih stabala korištenjem vizualnih metoda i arborikulturnihinstrumenataDoktorski rad IIKorištenjem zvučnog tomograma i rezistografa moguće je točno locirati područja oslabljelog drva u unutrašnjosti stabla, dok fraktometrom nije moguće.Stabla hrasta kitnjaka koja posjeduju vidljive simptome i greške drva nemaju manju stabilnost od stabala bez grešaka i simptoma. Povećanje vlažnosti tla dovodi do smanjenja stabilnosti stabla, međutim razlika smanjenja nije statistički značajna.Upotrebom suvremenih arborikulturnih instrumenata za otkivanje opasnih stabala uz upotrebu vizualnih metoda prosudbe se utječe na povećanje sigurnosti u urbanim šumama.
Hazardous trees can cause significant damage if a portion of a tree or the entire tree falls on a potential target. Assessment of hazardous trees can be made visually or using instrumental methods. Tree decay funghi cause degradation of wood in living trees which increases hazard for tree breakage. Tree stability is influenced by tree and site characteristics.Assessment of hazardous trees research has been conducted in urban forests that are included in management unit Park-šume grada Zagreba, in forest sites Granešina, Tuškanac, Zelengaj and Jelenovac.Results accomplished in the assessment of hazardous trees using visual methods indicate that there is a small number of hazardous trees. Among used visual assessment methods differences in results have been confirmed. When using EHT method a higher hazard rating is archived than when using VTA method. Bulge symptoms have the highest influence on VTA hazard rating while defected dead tree in the crown of the tree and restricted root area has the highest influence on EHT hazard rating.Using sound tomograph and resistograph it is possible to accurately locate areas of degraded wood in a living tree, on the other hand when using fractometer this is not possible.The sessile oak trees that have visible symptoms and tree defects do not have lower tree stability than trees without defects and symptoms. Increase in soil moisture leads to decrease in tree stability but difference in reduction is not statistically significant.Using modern arboricultural instruments for detection of hazardous trees, increase in safety of urban forests can be archived.
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