Data processing wireless systems for measuring propane / butane gas

U ovom radu predstavljen je i opisan sustav za obradu i prikaz podataka o količini plina u zraku. Kako je ukapljeni naftni plin otrovan i eksplozivan, napravljen je sustav za njegovu detekciju i mjerenje. Izmjereni podaci o plinu spremljeni su u EEPROM memoriju Arduina i prema potrebi korisnika, podaci se prebacuju iz memorije Arduina na osobno računalo. Bežičnu komunikaciji između sustava za alarmiranje i osobnog računala ostvarujemo pomoću Bluetooth modula pripremljenoga za Arduino okruženje i Bluetooth modula na osobnom računalu. Programskim kodom napisanim u programskom jeziku Matlab podatke iz EEPROM memorije Arduina prebacujemo i spremamo u predviđenu varijablu. Od spremljenih podataka iz varijable prikazuje se 2D „broj mjerenja/zasićenost“ dijagram.This thesis paper describes a system for processing and display of propan/butan gas (LPG) amount. Because LPG is toxic and explosive it is necessary to measure it. Arduino based system is proposed that measures the propan/butan gas amount and stores the data in EEPROM memory. Wireless communication between the Arduino system and a personal computer by means of a Bluetooth module is implemented. Program code is written in the MATLAB programming language for acquisition and display in the 2D diagram form

GROUNDWATER REGIME OF BIĐ-BOSUT FOREST AREA

U radu se donose prvi rezultati motrenja dinamike podzemnih voda na osam piezometarskih postaja raspoređenih unutar biđsko-bosutskoga šumskog područja. Piezometarske se postaje nalaze na području tri šumarije UŠP-a Vinkovci: Županja, Cerna i Strizivojna. Analizom je obuhvaćeno vremensko razdoblje od siječnja 1996. do prosinca 2011. godine, odnosno ukupno 16 cijelih godina. Osim podataka o podzemnim vodama u radu se prikazuju i osnovna klimatska obilježja istraživanog područja kroz podatke s meteoroloških postaja Gradište i Slavonski Brod. Osnovni je cilj ovoga priloga doprinijeti poznavanju recentnih hidrološkoklimatskih prilika biđsko-bosutskih nizinskih šuma. Osnovni statistički pokazatelji dinamike podzemne vode i klimatskih značajki izračunati su i prikazani na vegetacijskoj i godišnjoj razini. Najveća odstupanja srednjih vegetacijskih vrijednosti razina podzemnih voda od višegodišnjeg prosjeka zabilježena su 2001., 2003. i 2009. godine u negativnom smjeru (pad razine podzemne vode) te 1999., 2005. i 2006. u pozitivnom smjeru (povišenje razine podzemne vode). Odstupanja u navedenim godinama zabilježena su u svim šumskim zajednicama u otprilike sličnim iznosima. Najveći pad prosječne razine podzemne vode u vegetacijskom razdoblju zabilježen je 2009. godine u šumskoj zajednici hrasta lužnjaka i običnoga graba i iznosio je 177 cm niže od srednje vrijednosti cijeloga istraživanog razdoblja. Godine 2005. u svim je šumskim zajednicama zabilježeno pozitivno odstupanje od vegetacijskog prosjeka, a najveće je bilo u šumskoj zajednici hrasta lužnjaka i običnoga graba, gdje je iznosilo 233 cm. Ovo povišenje razine podzemne vode može se donekle dovesti u vezu s izrazito vlažnim uvjetima koji su vladali 2004. i 2005. godine što je pozitivno djelovalo na punjenje vodonosnika. U istim godinama i s istim predznakom zabilježena su i odstupanja apsolutnih vegetacijskih minimuma od srednjih vrijednosti cijeloga promatranog razdoblja.In this contribution we present first results of the long-term onitoring of groundwater dynamics in the Biđ-Bosut forest area located in the Eastern Croatia. Analysis encompassed groundwater level data measured twice per week on 8 piezometric stations during 16 years from January 1996 till December 2011. Data were analyzed on yearly and growing-season basis. Basic features of the climate in the area are also presented based on the meteorological data from two nearest meteorological stations, Slavonski Brod and Gradište. The main aim of the contribution is to add new findings to the existing knowledge-base on recent hydrological and climate dynamics of the lowland forest ecosystems in the Biđ-Bosut area. Departure of the groundwater levels from the long-term mean in the growing season were recorded in 2001, 2003 and 2009 (drop of the groundwater level), and in 1999, 2005 and 2006 (rise of the groundwater level). Significant rise of the groundwater levels during the growing season of 2005 was recorded in all forest types, due to the extremely moist condition of the climate in 2004 and 2005

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

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

Damage Dynamics and Structure of the Pedunculate Oak Tree Crowns in Stands in Microelevations and Microdepressions – Results from the Monitoring on Permanent Experimental Plots

Među širokim rasponom čimbenika koji definiraju odumiranje stabala hrasta lužnjaka, najznačajniju ulogu zauzima upravo oštećenost krošanja koja predstavlja prvi vidljivi simptom slabljenja vitalnosti stabla. Osim toga, u šumarskoj je praksi oštećenost krošnje ključni kriterij pri doznaci stabala u redovnim i sanitarnim sječama. Cilj je ovoga rada bio istražiti dinamiku oštećenosti krošanja stabala hrasta lužnjaka i utjecaja oštećenosti krošnje na prirast temeljnice tijekom duljeg razdoblja u dvije najvažnije šumske zajednice hrasta lužnjaka u Hrvatskoj. Istraživanja su obavljena na trajnim pokusnim plohama u zajednici hrasta lužnjaka i običnoga graba na gredi (II-G-10) i u zajednici hrasta lužnjaka s velikom žutilovkom u nizi (II-G-20). Obuhvaćeno je ukupno 38 pokusnih ploha od kojih je na 13 obavljena ponovna izmjera i procjena oštećenosti krošanja s intervalima izmjere od 9 do 17 godina. Udio stabala sa značajno oštećenom krošnjom naglo se povećava nakon starosti sastojine od oko 70 godina. Najveći intenzitet odumiranja (70 % u II-G-10 i 50 % u II-G-20) zabilježen je kod stabala s oštećenošću krošnje preko 60 %. U sastojinama V. i VI. dobnog razreda, stabla sa značajno oštećenom krošnjom imala su i značajno manji prirast temeljnice u usporedbi s vitalnim stablima sličnih prsnih promjera i širina krošnje. Udio značajno oštećenih stabala, kao i utjecaj oštećenja krošnje na prirast temeljnice, vrlo su slični u obje istraživane zajednice. Međutim, zabrinjava činjenica da je u sastojinama II-G-20 u samo jednom desetljeću evidentirano značajno povećanje sa 26 % na 70 % udjela značajno oštećenih lužnjakovih stabala, pa se postavlja pitanje u kojem će se smjeru dalje razvijati ove sastojine. Samo se nastavkom motrenja i daljnjim istraživanjima može razlučiti radi li se o velikim oscilacijama u toj šumskoj zajednici ili ipak o početku nepovratnoga procesa propadanja sastojina.The crown damage of a tree has a very prominent place among the broad spectrum of factors defining the pedunculate oak (Quercus roburL.) decline and dieback, largely due to the fact that it represents the first visible symptom of the decline in tree‘s vitality. Besides, crown damage is a key factor for the selection of trees with high risk of dying during the sanitary and salvage cuttings, in order to salvage high value timber that would be otherwise lost or severely degraded when the tree dies. Aim of this contribution is to investigate dynamics of crown damage of pedunculate oak trees, as well as the effect of the crown damage on tree’s basal area increment during longer time period in two most important types of pedunculate oak forests in Croatia. Research was done on permanent experimental plots situated in the stands of pedunculate oak and common hornbeam (II-G-10) and stands of pedunculate oak and Genista elata (II-G-20). In total, 38 permanent experimental plots were used, out of which 13 were re-measured with intervals of 9 to 17 years (Table 1). In first measurement, all trees on plots were permanently tagged, and map of tree locations and crown projections was made. Trees were measured for diameter at breast height (DBH), total tree height and height to crown base. Crown length was calculated as the difference between the total tree height and height to crown base, while the crown ratio was calculated as the ratio of crown length and total tree height. From the map of horizontal crown projections the average crown width was calculated as a mean of the maximal and minimal crown diameters. Assessment of the crown damage was done according to the methodology of the ICP Forests Programme, whereby the trees were tallied into following five crown damage (CD) classes: 0 (< 10 % CD), 1 (11-25 % CD), 2 (26-60 % CD), 3 (61-99 % CD) and 4 (100 % CD – dead tree). For some analyses trees were further grouped into two classes: healthy trees with crown damage of 25 % and less, and severely damaged trees with crown damage over 25 %. Results from this research are, however, not comparable to the damage assessment reports of the ICP Forests because of the different sampling strategies. On 13 plots the second measurement was made in which DBH of all trees still present on the plot was recorded, and the crown damage was assessed according to the same methodology used in the previous measurement, and furthermore, by the same observer. Average basal area increment per year (cm 2 year-1) per tree was obtained by dividing tree’s total basal area increment by the interval (number of vegetation periods) between the two measurements. Total number of oak trees analyzed was 749 and 540 in first and second measurement, respectively. Prior to the crown damage analyses, the basic structural features of the stands on re-measured plots, as well as morphological features of pedunculate oak trees in two forest types were analyzed (Table 2 and Figure 1). Stands of the forest type II-G-20 have much larger shares of oak trees in the total number of trees, and total stand basal area compared to the type II-G-10. oak trees in both types exhibit the same relation of tree height (Figure 1A) and crown width (Figure 1D) to DBH, but the crown length (Figure 1B) and crown ratio (Figure 1C) are higher in the forest type II-G-20. Reason for this lies probably in the effect that common hornbeam trees in the lower canopy layers have on the morphological development of oak trees in the stands of II-G-10 type, while the stands in the II-G-20 have almost no sub-canopy layers. Relationship between the share of oak trees with severe crown damage (> 25 %) and stand age was examined for the 33 plots of forest type II-G-10 spanning almost entire rotation length of pedunculate oak forests in Croatia (II. to VII. age class). Linear regression with logarithmic transformation of independent variable (stand age) was used for this analysis. According to the model, significant increase of severely damaged trees occurs after the stand age of 70 years (Figure 2A). The stands in the type II-G-20 departed significantly from the model in the first measurement, with only 26 % of severely damaged trees compared to 76 % in stands of II-G-10. By the second measurement, however, these plots also conformed to the behavior predicted by the model (Figure 2B), due to the deterioration of the overall crown condition. Distributions of oak trees by the CD classes in two measurements (Figure 3) reveal the direction of the crown damage dynamics, which is in more detail presented in the Figure 4. In both forest types, the change in crown class of the oak trees was predominantly in the direction of the worsening crown health status. Negative trend is more pronounced in the II-G-20 forest type. According to the CD classes recorded in the first measurement (Figure 5), decline intensity was most pronounced in the CD class 3, from which 70 % and 50 % of trees in forest types II-G-10 and II-G-20, respectively, died off by the second measurement. This result provides further foundation for the use of the CD assessments in the day-to-day forestry as a reliable indicator of the tree’s imminent death. Effect of crown damage on the basal area increment of oak trees was examined through: (i) the regression analyses of basal area increment per year per tree over DBH (Figure 6) and crown width (Figure 7), comparison of distributions of healthy and severely damaged trees over basal area increment classes (Figure 8), and by comparison of median values of basal area increment of healthy and severely damaged trees by forest types and stand age classes (Figure 9). Crown damage was found to have a significant impact on the basal area increment of pedunculate oak trees, with severely damaged trees having significantly lower basal area increment compared to healthy trees of the similar dimensions. These differences were very similar for both forest types

MODELING OF THE STAND BASAL AREA WITH STANDARD GROWTH EQUATIONS?

Temeljnica sastojine jedan je od osnovnih elemenata koji čine strukturu sastojine. U ovom radu prikazani su modeli razvoja sastojinske temeljnice, mješovitih sastojina hrasta lužnjaka i običnoga graba, pomoću standardnih funkcija rasta, koje se najčešće potrebljavaju u praksi, a razvoj zavisne varijable opisuju pomoću samo jedne nezavisne varijable (starosti). Realizacija postavljenog cilja ovog istraživanja provedena je kroz dvije faze rada: • Izrada modela razvoja temeljnice na razini gospodarskih sastojina. • Usporedba razvoja temeljnice sa prirasno-prihodnim tablicama. Istraživanje prve faze provedeno je na uzorku od 5060 odjela/odsjeka gospodarskih lužnjakovo-grabovih sastojina u Republici Hrvatskoj, ukupne površine od 75948,76 hektara. U drugoj fazi istraživanja napravljena je grafička usporedba razvoja sastojinske temeljnice, dobivenog u prvoj fazi istraživanja, s razvojem sastojinske temeljnice u prirasno-prihodnim tablicama domaćih autora. Dobiveni rezultati pokazuju kako razvoj sastojinske temeljnice mješovitih gospodarskih sastojina hrasta lužnjaka i običnoga graba, od početka do kraja ophodnje, karakterizira velika varijabilnost podataka, a modeli njezina razvoja, dobiveni odabranim standardnim funkcijama rasta, imaju sličan oblik i slične vrijednosti. Iz dobivenih rezultata razvidno je kako modeliranje razvoja temeljnice na razini sastojine standardnim funkcijama rasta previše statično i jednostavno prikazuje njezin razvoj, zbog vrlo malo informacija koje bi opisale dinamiku i zakonitosti razvoja promatranog elementa strukture u današnjem vremenu promijenjenih klimatskih uvjeta te sve naglašenijega antropogenog utjecaja na okolinu.Stand basal area is one of the fundamental stand structural elements. In this contribution we present growth models of the stand basal area in mixed pedunculate oak and common hornbeam forests developed with four standard growth functions. These functions prevail in practiacal use in forestry, and they describe development of basal are with only one independent variable: stand age. Research was conducted through two work stages: • Development of the stand basal area models based on data from managed forest stands. • Comparison of the stand basal area development with values tabulated in growth and yield tables. For the first phase of the research, we utilized the sample of 5,060 stands, or subcompartments of managed oak-hornbeam forests in Republic of Croatia, with total area of 75,948.76 ha. In the second phase we compare development trends of the stand basal area as achieved in the first research phase, with the development of the stand basal area tabulated in the growth and yield tables of domestic authors. Results of the research clearly show high variability of the stand basal area development with stand age, from the beginning to the end of the stand rotation in the mixed oak and hornbeam forests. Four models of the stand basal area development over age obtained in this research are very similar, both in the curve shape as well as in the model values over stand age. It is quite obvious, based on the results of this research, that modeling of the stand basal area development with univariate growth equations oversimplifies the multitude of the basal area growth trajectories that can occur in various forest stands, i.e. this type of models are to static to properly account for the stand basal area variability over stand age

Removal methods for invasive species Amorpha fruticosa – example of Odransko polje

Amorpha fruticosa is an invasive plant species that occurs in wide range of habitat types, including lowland floodplains. It grows very dense and changes the composition of communities by suppressing indigenous species, resulting in significantly reduced variety of flora in the area. In Odransko polje Amorpha fruticosa is widely spread. One of the tasks of Appropriate assessment of project "Flood protection system of Sisak area" was to determine the locations where material for embankment construction should be taken. The locations should be acceptable both from the aspect of nature protection and from the economic point of view (proximity to embankment due to lowering material transport costs, locations which are not private property, etc.). The locations where A. fruticosa is dominant plant were suggested for excavation. This paper will give overview of removal and disposal methods for this invasive species, which reduce the possibility of its spreading and re-appearing. Also, positive impacts of using proposed locations for material excavation will be shown – decrease in A. fruticosa abundance, increase of habitat diversity, increase in the presence of target habitats and target species habitats etc. Additionally, good practices for selection of excavation sites will be given, including guidelines for their sanation and landscape design

Effect of Acorn Size on Morphological Development of One-year-old Seedlings of Pedunculate Oak (Quercus robur L.) in Differing Light Conditions

Kakvoća sadnica povezana je s kvalitetom sjemena od kojega se proizvode, a u vrsta krupnoga sjemena, poput hrasta lužnjaka, kvaliteta sadnice nakon prve vegetacijske sezone povezana je s krupnoćom žira, odnosno količinom hranjiva pohranjenom u žiru. Stoga je cilj ovoga istraživanja ispitati utjecaj krupnoće žira na morfološki razvoj lužnjakovih sadnica tijekom prve godine života u uvjetima različite dostupnosti svjetla. Ukupno je u Bosnaplast kontejnere napunjene tresetom posijan 891 okularno zdravi žir hrasta lužnjaka porijeklom iz priznate sjemenske sastojine. Dio kontejnera postavljen je pod zasjenu od trske, kojim je ograničena dostupnost užitnog svjetla na oko 10 %. Na poduzorku od 25 biljaka obavljene su detaljne izmjere lisne površine, te je analizom suhe tvari ustanovljena biomasa glavnih dijelova biljaka. Na kraju vegetacije svim su biljkama izmjerene visine i promjer vrata korijena. Uloga krupnoće žira puno je izraženija kod sadnica uzgojenih u uvjetima punoga užitnog svjetla. S povećanjem krupnoće žira povećavala se prosječna visina i promjer vrata korijena, prosječna lisna površina sadnice i ukupna masa suhe tvari sadnice. Jedino ispitivano svojstvo koje se smanjivalo s povećanjem krupnoće žira je specifična lisna površina, što ukazuje na deblje plojke listova kod sadnica iz krupnijega žira. Kod lužnjakovih sadnica uzgojenih u zasjeni, utvrđeno je da je za mnoga od istraženih morfoloških svojstava važniji utjecaj dostupnoga svjetla, nego krupnoće žira. No, i u uvjetima zasjene sadnice hrasta lužnjaka uzgojene iz krupnijega žira, imale su veće prosječne visine i promjere vrata korijena od sadnica iz sitnoga žira. Rezultati istraživanja ukazuju da postoje mogućnosti za poboljšanje kvalitete u proizvodnji sadnica hrasta lužnjaka s obzirom na veličinu žira. Međutim, daljna detaljna istraživanja potrebna su kako bi se došlo do konačnih zaključaka i preporuka za praktičnu primjenu.Increase of the share of high-quality seedlings in the total production on the one hand enhances the production efficiency of the nursery production, and on the other hand improves the probability for successful planting in the field. The quality of the seedlings after the first growing season is related to the quality of the seeds used. In the tree species with large seeds, like pedunculate oak (QuercusroburL.), quality is related to the size of the seed, i.e. the amount of stored nutrients. Therefore, the aim of this contribution is to evaluate the effect of acorn size on the morphological development of pedunculate oak seedlings during the first growing season under contrasting light regimes. In total, 891 visually healthy acorns collected in the certified seed stand were planted in the “Bosnaplast” containers filled with peat (Figure 1). Part of the containers were kept in the shade of about 10 % of full light during the whole experiment. Before sowing, diameter, weight and length was measured on subsample of 200 acorns. Regression analysis showed that the acorn mass as the most important predictor of the nutrient content much more depends on the acorn diameter, than on the acorn length (Figure 2). Therefore, three acorn size classes were formed according to distribution of the acorn diameters: small acorns (. 16 mm of diameter), medium-sized acorns (16,1 mm to 17,9 mm of diameter) and large acorns (. 18 mm of diameter). During the sowing, acorns were measured for diameter and grouped into three classes of acorn size. Position of each acorn was recorded within the container and each container was labeled to facilitate the connection between the measurements of the acorn size and the subsequent measurements of the emerged seedlings. Subsample of 25 seedlings was removed from the experiment with fully developed leaves for detailed measurements of leaf area, and allocation patterns of dry biomass into three plant compartments: leaf, root, and stem. After the first growing season, height and root collar diameter were measured on all emerged seedlings. Effect of acorn size and light regime on morphological features of one-year old seedlings of pedunculate oak were examined with the analysis of variance. Following morphological features of seedlings were tested: height (Figure 3A and Table 1) and root collar diameter (Figure 3B and Table 1) of the seedlings, leaf area (Figure 4A and Table 2) and specific leaf area (Figure 4B and Table 2) of the seedlings, dry weight (Figure 5A and Table 3) and ratio of aboveground:underground dry weight of the seedlings (Figure 5B and Table 3). In seedlings grown in full sunlight increase in the acorn size resulted in the increase in average height and root collar diameters of the seedlings, average leaf area of the seedlings, and seedlings total dry weight. Specific leaf area was, on the other hand, smaller in seedlings from larger acorns. For the seedlings in the shade, light was the decisive factor influencing their morphological development, but still the seedlings from larger acorns were higher and had larger root collar diameters compared to the seedlings from smaller acorns. According to the results obtained in this research, it is safe to say that there is enough space for the improvements in the nursery production of pedunculate oak seedlings by taking into account the size of the acorns. However, further detailed research efforts are needed to deduce final conclusions and recommendations for the practical nursery production

Current state and the structural analysis of the mixed even-aged pedunculate oak and common hornbeam forests in Croatia

Background and Purpose: Mixed forests of pedunculate oak and common hornbeamare among the most important and most recognizable forest ecosystems in Croatiawith exceptional ecological, economical and sociological significance. Stand structure of these forests can be very complex, and their development highly dynamic due to the relationships between the add-mixed tree species aswell as vertical and horizontal stand structural elements. In the contemporary management of oak-hornbeam forests in Croatia growth and yield tables of domestic authors are used. Aimof this research is to give an overview of the current state of mixed forest stands of pedunculate oak and common hornbeam in Croatia through the analysis of available information on the area extent and basic stand structural features. Furthermore, the information obtained in the research are compared with the data from the growth and yield tables of domestic authors. Materials andMethods:Database used in this research is maintained by the state-owned forest management company Croatian Forests Ltd., and is comprised of the data collected within the regular forest management. In total, 5,060 forest stands (sub-compartments) with total area of 75,948.76 ha from whole area extent of pedunculate oak in Croatia were included in the analysis. Record for each stand included: phytocoenological community, forest area, stand age and age class. Width of the age classes is 20 years. Analyzed stand structural attributes were grouped for each stand by tree species (pedunculate oak, common hornbeam and other species) and as a whole, and included: stand density, basal area, volume, quadratic mean diameter and height. Finally, the shares of pedunculate oak and common hornbeam in the total basal area of each stand were calculated. Results and discussion: Total area of mixed pedunculate oak and common hornbeam forests in Croatia, according to the results of this research, amounts to 98,364.43 ha. Age structure of these forests is irregular, both by area, and by the number of forest stands with stands older than 80 years (5th age class and older) dominate in the total area. Most of the stands (> 68%) grow on 1st site class, i.e. the best site class. Structural elements of forest stands on 1st site class, show a large variation of the analyzed structural elements throughout the development of the stands (2nd to 8th age class). Highest variation is established in the shares of tree species in the total basal area of the stand. These values are under the direct influence of the growth and development of diameters at breast heights of trees of different species and of the corresponding diameter distributions. Basal area shares are also highly influenced by the silvicultural measures applied during the life-time of each particular stand. Comparison of actual stand structural attributes with the values indicated as optimal in the growth and yield tables of domestic authors revealed a high degree of discrepancy. Conclusion: As a general conclusion, it can be said that the currently used growth and yield tables only very rarely correspond with the actual state of forest stands in the field. New and improved methods of forest management planning are highly desirable at this moment in Croatian forestry

Natural Regeneration of Beech Forests in the Strict Protected Area of the Plitvice Lakes National Park

Background and Purpose: The study presents the results of an investigation of regeneration processes, growth, development and survival of young growth by field measurement and three-dimensional visualization of horizontal and vertical structure. The results are based on the ten-year investigation (1998-2009) on a permanent experimental plot in a mountain beech forest with dead nettle tree (Lamio orvale - Fagetum sylvaticae Ht. 1938) in conditions of passive protection. Materials and Methods: Basic structural indicators were measured (diameter at breast height and height), structural crown elements (size and shape, ground cover crowns) and the occurrence and survival of young growth as the basic conditions of natural regeneration. Particular emphasis in the investigation was paid to the development of crown structures and the process of natural regeneration during the 10 year period. Results and Conclusions: Investigation indicates the occurrence of young growth regeneration cores arising as a result of the die-back of one dominant beech tree with horizontal crown projections of 145 m2 which initiated the possibility of natural regeneration. The greatest change occurred in the beech seedling count, whose numbers increased fourfold from 3556 plants per hectare in 1998 to 12694 plants per hectare in 2009. The share of beech seedlings increased from 8.7% to 22.6% of all species of young growth and shrubs. Thus beech became dominant among the tree species regeneration. However, the majority of the young plants of beech are of poor quality and thus their further development in conditions of passive protection is questionable. The investigations also showed the possibility of a new approach to the study of the dynamics of crown structures and the process of natural regeneration by methods of three-dimensional visualization of horizontal and vertical structures. The methods presented offer a more graphic illustration of the development of stands and high quality presentation of the obtained results. For a long-term scientifically based plan, with the aim of reaching the most favourable decisions on the future of forest stands in protected areas, particularly in today’s conditions of climatic changes, continuous improvement and expansion of monitoring methods by means of a network of permanent experimental plots in all protected forest areas is necessary