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Abies koreana Wils., iztekanje smole ter kupčki strnjene smole na poganjkih, 3.6.2008 : analizni izvid
No full textStructure and dynamics of old-growth and near-natural beech forests in Europe
No full textIn past millennia, pure beech (Fagus sylvatica L.) forests covered vast areas of central and southeastern Europe. however, due to intensive forest exploitation
by humans, few old-growth remnants of these forests remain. These small remnants of the former forest provide invaluable information on structure and
natural processes and are important for understanding the natural spatial-temporal dynamics of beech forests. This basic information is also crucial for forest
management, which tries to mimic natural processes. As these old-growth forests are so rare, near-natural beech forests that have been unmanaged for decades
may provide a valuable source of information as well. In the present paper, we review the literature on old-growth and near-natural beech forests in Central
Europe in order to describe the structure (i.e. diameter and age structure, course woody debris, canopy structure, etc.) and dynamics (mortality, regeneration,
disturbance regimes, etc) of these ecosystems. In total, we included 22 forests that contained at least 7� % of beech in the species composition. we compared
our findings with data on fir-beech forests. Finally, some guidelines for close-to-nature management are presented
Shear strength development of the phenol–formaldehyde adhesive bond during cure
Get PDFThe development of the shear strength of the phenol-formaldehyde (PF) adhesive bond during curing was investigated. Five different PF adhesive mixtures and 1.1 mm thick peeled beech (Fagus sylvatica L.) veneer were used to produce lap-shear specimens, which were cured at a pressing temperature of 160°C. Dielectric analysis (DEA) and modified ABES (automated bonding evaluation system) were used to evaluate the physical-chemical and mechanical aspects of PF adhesive cure in a miniature hot-press. The degree of cure, which was calculated from conductivity data, was dependent on pressing time and the composition of the PF adhesive. An addition of rye flour to the PF adhesive significantly postponed the curing process as determined by DEA. It was found that the adhesive bond started to develop in the last stage of the curing (vitrification), by which time most of the physical-chemical conversion of the adhesive had been completed
Cambial activity and wood formation in beech (Fagus sylvatica) during the 2006 growth season
No full textCambial seasonal activity and the dynamics of xylem growth ring formation were studied during the 2006 growth season in mature beech (Fagus sylvatica) trees at a forest stand near Ljubljana, Slovenia. Cross-sections of tissues taken from living trees at weekly intervals were studied with light microscope. Cambial cell divisions began between 18 and 24 April, the cambium achieved maximum width (10-13 cell layers) at the end of May, and cell divisions ceased between 25 July and 16 August. Dormant cambium contained 3 to 5 cell layers. Fitting xylem increments to the Gompertz function showed that the period of most intense cell production was from 30 May to 6 June 2006. Th e average width of fully formed xylem growth rings was 2552 μm, and the time necessary for their formation was 100 days. Although the investigated trees were healthy and of comparable age, the parameters of the Gompertz function showed diff erences in radial growth patterns among trees
Dendrochronological investigation of wood from Varaždin old castle
No full textTijekom arheoloških istraživanja na Starom gradu u Varaždinu, a iskopavanja suprovedena kao dio Projekta BASTION u sklopu međunarodnog INTERREG III A programa, otkriveni su dijelovi dviju drvenih konstrukcija. U sjevernom jarku bili su pronađeni ostaci mosta ili prilazne rampe, koja je vodila prema vratima srednjovjekovne četvrtaste kule, a u zapadnom unutarnjem jarku otkriveni su ostaci drvene obrambene ograde - palisade. Na osnovi raspoloživihpovijesnih podataka bilo je procijenjeno da drvo pripada konstrukcijama s vremenskim rasponom nastanka od 13. do sredine 16. stoljeća. Nakon vađenja iz zemlje drvo je bilo odgovarajuće pohranjeno u podrumu muzeja u Varaždinu pa se nije osušilo niti je doživjelo oštećenja. Prema uputama Odsjeka za drvnu tehnologiju Univerziteta u Ljubljani, pripremljeni su manji uzorci koji su poslani na dendrokronološku analizu u Ljubljanu. Tamo je drvo fino obrađeno te su provedeni identifikacija i dendrokronološko datiranje u skladu s važećom metodologijom (ČUFAR et al. 2006). Rezultati istraživanja su sljedeći: (1) uzorci iz pristupnog mosta u sjevernom jarku (sonda VII) bili su: daska (VAR1A i VAR2A) iz jelovine (Abies alba) dendrokronološko datirana ugod. 1406., dva pilota iz hrastovine (Quercus sp.) datirana u 1374. (VAR12A) i 1394. (VAR13A) te mali komad drva hrasta (VAR14A) datiran u 1400. godinu. Uzorak pilota ili ostatak debla od drva pravoga kestena (Castanea sativa) s očuvanom korom nismo mogli datirati jer je imao premalo godova. Uzorci VAR5A iVAR8A iz zapadnog jarka (sonda VIII) bili su iz aksialno raskoljenih trupaca hrasta i predstavljali su dijelove drvene obrambene palisade te su bili datirani u 1415. i 1404. godinu. Datacije su bile provedene s referentnim kronologijama laboratorija u Ljubljani. U DK / UDC 902.67(497.5 Varaždin) 904:725.96](497.5 Varaždin)"12/15. Nijedan od uzoraka nije imao sačuvanu bjeljiku niti koru te zato navedeni datumi predstavljaju godinu nastanka krajnjeg perifernoga goda, sječa stabla i postavljanje konstrukcije u svim su se slučajevima dogodili nakon navedenih datuma. Most je bio podignut nakon 1406., a palisada poslije 1415. godine. S obzirom na procijenjeni broj godova koji nedostaju, pretpostavljamo da bi obje konstrukcije mogle biti sagrađene istodobno ili pak u kratkom razmaku, poslije 1415. i prije 1445. godine. U tomje razdoblju Stari grad bio u vlasništvu grofova Celjskih. Izvori spominju da je 1446. Janko Hunjadi napao i spalio Varaždin, a utvrdu nije mogao osvojiti jer je bila dobro branjena drvenom ogradom. Dendrokronološko datiranje i interpretacija s povijesnim izvorima pokazuju važnost interdisciplinarnih istraživanja. Datacija drvenih konstrukcija sa Staroga grada u Varaždinu je, uz datiranje nalazišta Torčec-Gradić (ČUFAR i SEKELJ-IVANČAN, u ovom broju), među prvim uspješnim aplikacijama dendrokronologije u arheologiji u Hrvatskoj s uporabom referentnih kronologija iz Slovenije
Red deer (Cervus elaphus) bark stripping on spruce with regard to spatial distribution of supplemental feeding places
No full textForest damages caused by red deer and some other large herbivore species occasionally feeding on tree bark, are a grave ecological and economic problem in many parts of the world. Winter supplemental feeding is commonly used to mitigate the problem, but its effects are poorly known. This study, carried out at Pohorje (Slovenia) and including over 2,300 trees, used binary logistic regression to analyse the effects of supplemental feeding and many other factors on the probability of bark stripping on spruce. The probability of bark stripping depends on distance from the forest edge, density, age and tree species diversity of stands, slope and aspect of terrain, and red deer density; contrary to expectations, it is not related to distance from feeding places. As much as 35% of spruce trees were damaged. The damage was the highest in younger, denser pure spruce stands, whose favourable protective and microclimatic conditions (thinner snow cover, higher effective temperatures) make them a preferred winter habitat for red deer. They contain,however, little other food but bark. To prevent / diminish bark stripping we propose a stronger thinning of such stands. Supplemental feeding may reduce damage only in exceptional cases, when animals are lured and concentrated in less sensitive areas, but in general we advise against the use of this measure due to its other negative effects