THE NUTRITIONAL STATUS OF COMMON BEECH (FAGUS SYLVATICA L.) AND SILVER FIR (ABIES ALBA MILL.) ON MEDVEDNICA

U Hrvatskoj se od 1995. godine provode istraživanja na plohama intenzivnog motrenja (Razina II) u sklopu i po metodama Međunarodnog programa za procjenu i motrenje utjecaja zračnog onečišćenja na šume (UN-ECE ICP Forests). U radu se daje usporedba višegodišnjeg niza podataka (1999.–2004.) o stanju ishrane obične bukve (Fagus sylvatica L.) i obične jele (Abies alba Mill.) na plohi intenzivnog motrenja 103 «Sljeme» sa stanjem ishrane na drugim plohama u sastojinama obične jele i obične bukve na području Medvednice. U uzorcima lišća i iglica određene su ukupne koncentracije dušika, fosfora, kalija, kalcija i magnezija koje su uspore|ene s graničnim vrijednostima (GV). Ti su podaci tako|er stavljeni u kontekst klimatskih prilika područja. Istraživani lokaliteti na području Medvednice razlikuju se u pogledu uvjeta za ishranu drveća, a na stanje ishrane utjeću i antagonizmi iona.The research on intensive monitoring plots (Level II) as a part and according to the methods of the International Co-operative Programme for Assessment and Monitoring of Air Pollution Effects on Forests (UN-ECE ICP Forests) has been conducted in Croatia since the year 1995. In this paper a comparison is given of data on foliar composition of Common beech (Fagus sylvatica L.) and Silver fir (Abies alba Mill.) in the years 1999 to 2004 on intensive monitoring plot No. 103, «Sljeme» with their nutritional status on beech-fir plots in other parts of Medvednica mountain. The total concentrations of nitrogen, phosphorous, potassium, calcium and magnesium were determined in the samples of foliage, and these data were put in the context of climate properties in the area of research. The investigated localities differ regarding the conditions they provide for the nutrition of trees, and the nutritional status further depends on ion antagonisms

DEFOLIATION OF FOREST TREES IN CROATIA IN THE PERIOD 2001-2011

Međunarodni program za procjenu i motrenje utjecaja zračnog onečišćenja na šume (International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests, skraćeno ICP Forests) osnovan je 1985. godine u okviru UNECE Konvencije o dalekosežnom prekograničnom onečišćenju zraka (CLRTAP), s mandatom da motri utjecaj antropogenih čimbenika (pogotovo zračnog onečišćenja) i prirodnih čimbenika stresa na stanje i razvoj šumskih ekosustava u Europi te da doprinese boljem razumijevanju uzročno-posljedičnih veza u šumskim ekosustavima Europe. Hrvatska se projektu priključila 1987. godine. Značajna se osutost krošanja šumskog drveća u Hrvatskoj u razdoblju od 2001. do 2011. godine kretala u rasponu od 20,6 (2002.) do 27,7 % (2010.). U razdoblju od 2001. do 2005. godine značajna osutost listača kretala se u rasponu od 14,4 do 19,2 %, a kontinuirani rast bilježimo od 2006. godine. Kod četinjača značajna je osutost naglo porasla u 2003. godini, nakon čega se zadržava iznad 70 % do 2006. godine, s maksimumom u 2005. godini (79,5 %). Isto tako, kod nekih je vrsta (obična bukva, poljski jasen, hrast kitnjak) zabilježeno povećanje značajne osutosti nakon sušnih godina, dok kod npr. hrasta lužnjaka takva pojava nije primijećena. Rezultati ovog istraživanja pokazuju kako se osutost krošanja šumskog drveća, u ovisnosti od vrste, može povezati s klimatskim svojstvima kako tekuće, tako i prethodnih godina.The International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests - ICP Forests started in 1985 in the framework of the UNECE Convention on Long-Range Transboundary Air Pollution (CLRTAP), with the mandate to monitor the effects of anthropogenic factors (in particular air pollution) as well as natural stress factors on the condition and development of forest ecosystems in Europe and to contribute to a better understanding od cause-effect relationships in forest ecosystem functioning in various parts of Europe. Croatia joined the programme in 1987. The share of moderately to severely defoliated trees in the period 2001-2011 ranged from 20,6 % (2002) to 27,7 % (2010). For broadleaves, the share was between 14,4 % and 19,2 %, and a continuous growth of defoliation is recorded since 2006. The share of moderately to severely defoliated conifers sharply grew from 2003 to 2006, with a maximum in 2005 (79,5 %). With some single species (common beech, narrow-leaved ash, sessile oak) also a rise in defoliation is recorded after dry years, while with others, such as pedunculate oak, dry years have no discernible effect on the crown condition. The results of monitoring show that crown defoliation can, depending on the species, be linked to climate properties of either current, or past years

Defoliation of Forest Trees in Croatia in the period 2006 – 2009

S obzirom na stav da je najvažniji uzročnik propadanja šuma zračno onečišćenje, 1985. godine je u okviru UNECE Konvencije o dalekosežnom prekograničnom onečišćenju zraka (CLRTAP) osnovan Međunarodni program za procjenu i motrenje utjecaja zračnog onečišćenja na šume (International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests, skraćeno ICP Forests), u koji se Hrvatska uključila 1987. godine. Prednost monitoringa (trajnog motrenja) u odnosu na jednokratna istraživanja je u dobivanju vremenskog niza podataka koji omogućuje ispravnije zaključivanje o stanju pojava koje, u ovome slučaju, variraju na godišnjoj razini. Motrenje se provodi na mreži točaka Razine 1 (bioindikacijske točke razmaka 16 km) i osnovnoj mreži točaka (točke razmaka 4 km), a ključnu ulogu u Programu ima vizualna procjena osutosti krošanja. Vrijednosti značajne osutosti su vrlo visoke u Upravama šuma Podružnicama Vinkovci, Zagreb, Delnice i Buzet, a niske u UŠP Bjelovar i Koprivnica.Visok postotak značajne osutosti u UŠP Delnice i Vinkovci posljedica je visokeosutosti obične jele, odnosno hrasta lužnjaka. U UŠP Buzet, visok postotak značajne osutosti posljedica je visokih vrijednosti značajne osutosti gotovo svih promatranih vrsta. Porast značajne osutosti svih vrsta traje od 2002. godine, a listača od 2003. godine. Kod četinjača od 2006. godine bilježimo lagan pad osutosti.In response to widespread concern that air pollution could affect forest condition, the International Co-operative Programme on the Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) was established by the Convention on Long-range Transboundary Air Pollution (CLRTAP) under the United Nations Economic Commission for Europe in 1985. Croatia joined the Programme in 1987. The advantage of monitoring is in obtaining a time series of data that enables correct deduction on the phenomena that, in this case, vary on annual basis. Monitoring is conducted on two networks: Level I (so called bioindication plots at 16 x 16km distance) and basic network (4 x 4 km distance of plots). Defoliation, the key parameter for assessing forest ecosystem condition, is assessed according to ICP Forests Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. Defoliation is high in Forest Branch Offices Vinkovci, Zagreb, Delnice and Buzet, and low in Bjelovar and Koprivnica (Fig. 5). The high percentage of moderately to severely damaged trees in Forest Branch Office Delnice and Vinkovci is the result of intensive dieback of silver fir and pedunculate oak, respectively. In Forest Branch Office Buzet, a high percentage of moderately to severely damaged trees is the result of high defoliation values in almost all surveyed species. In Forest Branch Offices Gospić and Senj, moderate to severe damage of silver fir trees in year 2009 is significantly lower that the corresponding value in the bioindication and basic plot network in Croatia, while it is somewhat higher in Forest Branch Offices Delnice and Ogulin. Very high values of percentages of moderately to severely damaged trees of pedunculate oak in the year 2009 were present in Forest Branch Offices Požega, Zagreb, Našice and Osijek, and very low in Bjelovar and Koprivnica. Moderate to severe damage of beech is significantly higher than the value for Croatia in Forest Branch Offices Zagreb, Delnice and Senj, and lower in Bjelovar, Sisak, Karlovac and Našice. The rising percentage of moderately to severely damaged trees of all species started in 2002, and for broadleaves in 2003. Conifers, on the other hand, have a decreasing trend of defoliation since 2006 (Tabs. 2–4)

The Role of Site in Predisposition ofAustrian Pine (Pinus nigraArnold) to Pathogenic FungusSphaeropsis sapinea(Fr.) Dyko et Sutton in Istria (Croatia)

Provedenim istraživanjem 2001. godine utvrđeno je različito zdravstveno stanje crnoga bora (Pinus nigraArnold) u Istri, od potpuno zdravih stabala i kultura, do lokacija s izrazitim simptomima odumiranja izbojaka, grana i krošnji. Na svim istraživanim lokalitetima utvrđena je prisutnost gljive Sphaeropsis sapinea.Analizom zdravstvenog stanja borovih kultura utvrđena je značajna uloga staništa u predispoziciji crnoga bora na zarazu ovom gljivom u sušnim razdobljima. Utjecaj matične podloge i tipa tla kroz ishranu crnoga bora posebice dolazi do izražaja u sadržaju dušika i kalija, te njihova odnosa (N/K) kao važnog predisponirajućeg čimbenika. U takvim uvjetima uloga kalija u biljci je važna s obzirom na njegov utjecaj na opskrbljenost vodom, otpornost na sušu i patogene organizme. Najniže N/K vrijednosti utvrđene su u iglicama borova na tlima flišne matične podloge, na lokalitetima na kojima nisu zabilježeni simptomi odumiranja izbojaka i grana. Na tlima vapnenačko-dolomitne matične podloge uz ishranu (utjecanu tipom tla), posebice vidljivo s višim N/K vrijednostima, u kompleksnoj ulozi staništa dodatno važnu ulogu igraju dubina tla, stjenovitost, ekspozicija i inklinacija u predispoziciji crnoga bora na zarazu ovom gljivom. Pokusom inokulacije sadnica crnoga bora potvrđena je patogenost gljive S.sapineai utvrđena jednaka sposobnost da izolati dobiveni iz bolesnih i zelenih organa crnoga bora (bez vidljivih simptoma bolesti) mogu prouzročiti odumiranje kore. Prihrana borovih sadnica amonijevim sulfatom utjecala je na povećanje visine biljaka i na dužinu nekroza kore, čime je potvrđena uloga dušika u predispoziciji borova na nastanak i širenje bolesti.Austrian pine (Pinus nigra Arnold) was commonly planted during the last century in Croatia. Afforestation took place on various sites to prevent land from erosion and, or to restore forest vegetation, mainly in karst areas. Since 1992 the study on health status of Austrian pine plantations in Croatia revealed significant dieback symptoms in some areas as the consequence ofSphaeropsis sapineaoccurrence. Research carried out in November 2001 found the fungus presence with different impact to P. nigrain Istria, healthy sites and also ones with various disease symptoms were observed (Figure 1, Table 1). In plantations which revealed good health statusS. sapineawas found only on cones, but in plantations with dieback symptoms its presence was found in needles, shoots and branches, causing in some cases dieback of trees. According to dieback symptoms observed, research localities were categorised in four health categories as shown in Figure 1. It was revealed that along the drought (Figures 19 and 20, an example for period 1961–1990 vs. 1999), the site conditions also played an important role in pines’ predisposition to fungus attack during last years. This conclusion was supported by analyses of nutrition status in pines and site conditions (soil sub-types, soil types and depth, site rockiness, exposition and inclination, Table 1). Analyses of nutrition status obtained clear difference among sites comparing the nitrogen (N) and potassium (K) concentrations in pine needles (Figures 6–11). In sites with lower N/K ratio the disease symptoms were not observed, but in sites with increased N/K ratio the dieback symptoms were revealed, following nitrogen and potassium relation in general (Figures 12 and 13). According to Brown (1999) fertilization only by nitrogen can increase the susceptibility of broadleaved trees to pathogenic organisms due to the influence of nitrogen on growth of aboveground plant biomass, and imbalance of above- and belowground plant parts biomass can lead to the increased susceptibility of trees to water stress. Higher nitrogen concentartions as pines’ predisposition to S. sapinea were confirmed by De Kam et al. (1991), Van Dijk et al. (1992) and Stanosz et al. (2004). Opposite to nitrogen, potassium play important role in plant resistance to drought and pathogenic organisms (Bergmann 1992, Marschner 1995). Inoculation experiment in Austrian pine seedlings confirmed the S. sapinea pathogenicity and also the same capability of isolates obtained from healthy needles (VIPAVA, IMI 368260) and ones with symptoms (DP 04-1 and DP 06-3, described in Diminić et al. 2004) to cause bark necrosis. Previous fertilization with ammonium sulphate caused increased seedlings growth according to treatments: 0, 20, 40 and 80 g/m2, and also increased length of bark necrosis in inoculated pines (Tables 2 and 3, Figures 14–18), which supported the nitrogen role in disease development. According to up-to-day worldwide knowledge and results of our research, it can be concluded thatS. sapineacan live (latent phase) in healthy looking pines in Istria. And, in drought periods it can turn to serious pathogen, causing dieback in predisposed trees. It this circumstances, site play an important role in pines’ resistance to disease, indirectly influencing appearance (or not) of various dieback symptoms

European-wide forest monitoring substantiate the neccessity for a joint conservation strategy to rescue European ash species (Fraxinus spp.)

European ash (Fraxinus excelsior) and narrow-leafed ash (F. angustifolia) are keystone forest tree species with a broad ecological amplitude and significant economic importance. Besides global warming both species are currently under significant threat by an invasive fungal pathogen that has been spreading progressively throughout the continent for almost three decades. Ash dieback caused by the ascomycete Hymenoscyphus fraxineus is capable of damaging ash trees of all age classes and often ultimately leads to the death of a tree after years of progressively developing crown defoliation. While studies at national and regional level already suggested rapid decline of ash populations as a result of ash dieback, a comprehensive survey at European level with harmonized crown assessment data across countries could shed more light into the population decline from a pan-European perspective and could also pave the way for a new conservation strategy beyond national boarders. Here we present data from the ICP Forests Level I crown condition monitoring from 27 countries resulting in > 36,000 observations. We found a substantial increase in defoliation and mortality over time indicating that crown defoliation has almost doubled during the last three decades. Hotspots of mortality are currently situated in southern Scandinavia and north-eastern Europe. Overall survival probability after nearly 30 years of infection has already reached a critical value of 0.51, but with large differences among regions (0.20–0.86). Both a Cox proportional hazard model as well as an Aalen additive regression model strongly suggest that survival of ash is significantly lower in locations with excessive water regime and which experienced more extreme precipitation events during the last two decades. Our results underpin the necessity for fast governmental action and joint rescue efforts beyond national borders since overall mean defoliation will likely reach 50% as early as 2030 as suggested by time series forecasting.European-wide forest monitoring substantiate the neccessity for a joint conservation strategy to rescue European ash species (Fraxinus spp.)publishedVersio

Habitat Characteristics of Bracken-Covered Areas Intended for Afforestation in Ličko Sredogorje

Background and Purpose: Forest cultures in continental part of Croatia are mainly based on bracken-covered areas and moors on deserted agriculture soils and pastures. Successful afforestation i.e. establishment of forest cultures depends among other things on the understanding of habitats and ecology of forest trees. The choice of best species of forest trees for afforestation needs to be based on the research in soil and climate characteristics of target habitats. The aims of this research were to show mesoclimatic characteristics of Ličko sredogorje and microclimatic and pedological characteristics of Ličko polje. Also, based on habitat characteristics and ecology of forest trees, the aim was to determine species of forest trees suitable for afforestation of bracken-covered areas. Materials and Methods: Climate, microclimate, pedological and plant nutrition researches were done at the area of Lika highlands. Climate analysis was done according to air temperatures, amount of precipitation, relative air humidity and other climate elements and appearances. Composite soil samples were taken from the depth of 0-30 cm in order to determine plant nutrition potential. Samples were prepared for further analysis in the laboratory. Results: The highest average annual air temperature of 9.6 °C was found at weather station Gračac and the lowest at Korenica station (8.1 °C). Average amount of precipitation for this region was around 1500 mm. Monthly rain factors were ranging from arid to perhumid. Considering thermal character of the climate, the area has moderately warm climate. Average volumetric soil humidity is 14.2 %. Soil has strong acid reaction, is very humus, good to richly supplied with total nitrogen, content of physiologically active phosphorus and potassium is low, and C/N ration normal. Conclusions: According to habitat characteristics in the area of Ličko sredogorje and ecological demands of forest tree species, forest cultures of Common birch (Betula pendula Roth.), Common spruce (Picea abies Karst.), Eastern white pine (Pinus strubus L.), Black pine (Pinus nigra subsp. austriaca Asch i Gr.), Common pine (Pinus sylvestris L.) and European trembling aspen (Populus tremula L.) can be established

Povezanost mortaliteta obične jele (Abies alba Mill.) na području Fužina s klimatskim i strukturnim parametrima

Tree dieback is a complex process involving negative impact of various abiotic, biotic and anthropogenic factors. Climate change, comprising all those effects, is generally considered as the largest threat to forest ecosystems in Europe. Although the scale of climate change impacts on forests is not yet fully understood, especially on the regional or species level, significant damage seems to be caused by weather extremes, such as drought and strong winds. With the expected increase in the number, length, and/or intensity of extreme weather events in Croatia, research into the causes of tree mortality is both important and timely.Silver fir is the most damaged and endangered conifer tree species in Croatia. The dieback of silver fir can be attributed to various factors, therefore the goals of this research were to determine the mortality of silver fir trees (by number and volume) for various causes of mortality, among which the climatic and structural parameters were of most interest. The twenty-year data for tree mortality in pure silver fir stands in the area of Fužine (Gorski kotar, Croatia) were collected and analysed. The largest number and volume of dead trees was caused by complex (multiple causes) dieback in the overstorey (0,75 N/ha, 2,35 m3/ha), and the smallest (0,17 N/ha, 0,02 m3/ha) by dieback of supressed trees. No significant differences were determined regarding the timing of tree death for different causes of mortality. Climatic parameters (drought, air temperature, PET) and structural parameters of the stands (tree DBH, social position, crown diameter, shading, physiological maturity) as well as plot inclination were found to be the factors of a significant influence on the mortality of silver fir trees.Obična jela najoštećenija je i najugroženija vrsta crnogoričnog drveća u Republici Hrvatskoj. Odumiranje stabala obične jele pripisuje se različitim uzročnicima, stoga je cilj ovog istraživanja bio utvrditi mortalitet stabala obične jele po broju stabala i volumenu za različite skupine uzroka mortaliteta, među kojima su najvažniji bili klimatski i strukturni parametri. Prikupljeni su i analizirani podaci o mortalitetu stabala obične jele u čistim jelovim sastoji­nama na području Fužina (Gorski kotar, Hrvatska) u razdoblju od dvadeset godina. Prema iznosu mortaliteta sta­bala iskazanom u broju stabala najveći mortalitet uzrokovan je kompleksnim odumiranjem stabala (0,75 N/ha) u gornjem sloju sastojine, a najmanji mortalitet uzrokuje prirodno izlučivanje potisnutih stabala (0,17 N/ha). S obzirom na drvni volumen najveći mortalitet uzrokovan je kompleksnim odumiranjem stabala (2,35 m3/ha), a najmanji prirodnim izlučivanjem (0,02 m3/ha). Nisu utvrđene velike razlike u vremenu odumiranja stabala prema različitim skupinama uzroka odumiranja. Klimatski uvjeti (suša, temperatura zraka, PET), strukturni elementi sastojine (prsni promjer, socijalni položaj, promjer i osvjetljenost krošnje te fiziološka zrelost), kao i nagib terena znatno utječu na mortalitet stabala obične jele

Climate and relief properties influence crown condition of common beech (Fagus sylvatica L.) on the Medvednica massif

Background and Purpose: Common beech is a dominant broadleaved tree species in European forests, and also on the Medvednica massif. Since climate is a decisive factor in the development of a certain type of vegetation, it might have an equally important role in its survival. The influence of relief properties on the crown condition of common beech (Fagus sylvatica L.) can also be significant, since beech stands on Medvednica vary in their elevation and exposition. Materials and Methods: Twelve common beech research plots, with complete defoliation data sets in the period 2004–2006 were chosen to represent the variety of environmental conditions present on the Medvednica massif in the western Pannonian region of Croatia. Climate parameters used in the model included annual precipitation (AP), precipitation in the vegetation period (VP), mean annual air temperature (AT), and mean air temperature in the vegetation period (VT). The elevation (EL) of the experimental plots and data from the meteorological station of Puntijarka were used to obtain an estimate of the AT, VT, AP and VP on each research plot. Results: The share of moderately to severely damaged trees (crown defoliation over 25%) was highest in 2004, an expected result of the 2003 drought. This value was significantly higher than in the following two years. The determining climate parameter explaining the changes in defoliation was VP, and the most decisive relief parameter was EL. Defoliation was higher with low VP and higher EL. D was higher predominantly on southern expositions. Conclusions: Climate and relief properties were found to significantly influence the crown condition of beech trees. Although there is a significant positive trend of temperature change on Medvednica, in the period 2004–2006 precipitation in the vegetation period had the dominant effect on the crown condition