| water stress responses of seedlings of four mediterranean oak species. | effects of water stress on phenology, growth, stomatal activity and water status were assessed from april to november 1996 in 2-year-old seedlings of quercus frainetto ten. (quercus conferta kit.), quercus pubescens willd., quercus macrolepis kotschy (quercus aegilops auct.) and quercus ilex l. growing in containers in northern greece. all four species developed more than 50% of their total leaf area before the beginning of june--an adaptation to arid climates. well-irrigated plants tended to de ... | 2000 | 11269958 |
| seasonal embolism and xylem vulnerability in deciduous and evergreen mediterranean trees influenced by proximity to a carbon dioxide spring. | we investigated how proximity to natural co(2) springs affected the seasonal patterns of xylem embolism in quercus ilex l., quercus pubescens willd., fraxinus ornus l., populus tremula l. and arbutus unedo l., which differ in leaf phenology and wood anatomy. xylem embolism was evaluated in both artificially dehydrated branches and in hydrated apical branches collected at monthly intervals during a 20-month sampling period. initial specific hydraulic conductivity was also evaluated. we found spec ... | 1999 | 12651570 |
| crown condition surveys in italian forests: issues in reporting findings. | this study examines defoliation and discoloration findings collected throughout the italian level i network between 1997 and 2000. prior to this period no quality assurance procedures had been implemented, so that earlier findings cannot be considered reliable. the aim of the study is to compare different indices used in reporting findings, in order to determine the full potential and limitations of each. in international surveys, findings are normally expressed in terms of individual trees pres ... | 2003 | 12841687 |
| modeling tree water deficit from microclimate: an approach to quantifying drought stress. | tree water deficit estimated by measuring water-related changes in stem radius (deltaw) was compared with tree water deficit estimated from the output of a simple, physiologically reasonable model (deltawe), with soil water potential (psisoil) and atmospheric vapor pressure deficit (vpd) as inputs. values of deltaw were determined by monitoring stem radius changes with dendrometers and detrending the results for growth. we followed changes in deltaw and deltawe in pinus sylvestris l. and quercus ... | 2005 | 15574396 |
| utility of its sequence data for phylogenetic reconstruction of italian quercus spp. | nuclear ribosomal dna sequences encoding the 5.8s rna and the flanking internal transcribed spacers (its1 and its2) were used to test the phylogenetic relationships within 12 italian quercus taxa (fagaceae). hypotheses of sequence orthology are tested by detailed inspection of some basic features of oak its sequences (i.e., general patterns of conserved domains, thermodynamic stability and predicted conformation of the secondary structure of transcripts) that also allowed more accurate sequence ... | 2004 | 15619447 |
| real-time pcr detection of biscogniauxia mediterranea in symptomless oak tissue. | real-time pcr, based on taqman chemistry, was used to detect biscogniauxia mediterranea, a fungal pathogen that after a long endophytic phase may cause charcoal disease in oak trees. | 2005 | 15960754 |
| localized ozone fumigation system for studying ozone effects on photosynthesis, respiration, electron transport rate and isoprene emission in field-grown mediterranean oak species. | we used a localized ozone (o3) fumigation (lof) system to study acute and short-term o(3) effects on physiological leaf traits. the lof system enabled investigation of primary and secondary metabolic responses of similarly and differently aged leaves on the same plant to three different o3 concentrations ([o3]), unconfounded by other influences on o3 sensitivity, such as genetic, meteorological and soil factors. to simulate the diurnal cycle of o3 formation, current-year and 1-year-old quercus i ... | 2005 | 16137938 |
| intra-annual radial growth and water relations of trees: implications towards a growth mechanism. | there is a missing link between tree physiological and wood-anatomical knowledge which makes it impossible mechanistically to explain and predict the radial growth of individual trees from climate data. empirical data of microclimatic factors, intra-annual growth rates, and tree-specific ratios between actual and potential transpiration (t pet(-1)) of trees of three species (quercus pubescens, pinus sylvestris, and picea abies) at two dry sites in the central wallis, switzerland, were recorded f ... | 2006 | 16556628 |
| the biogenic volatile organic compounds emission inventory in france: application to plant ecosystems in the berre-marseilles area (france). | an inventory describing the fluxes of volatile organic compounds (vocs), isoprene and monoterpenes, and other vocs (ovocs) from the biosphere to the atmosphere, has been constructed within the framework of the escompte project (field experiments to constrain models of atmospheric pollution and transport of emissions). the area concerned, located around berre-marseilles, is a mediterranean region frequently subject to high ozone concentrations. the inventory has been developed using a fine scale ... | 2006 | 17011024 |
| variation in cold hardiness and carbohydrate concentration from dormancy induction to bud burst among provenances of three european oak species. | although cold hardiness is known to be a major determinant of tree species distribution, its dynamics and the factors that regulate it remain poorly understood. variation in cold hardiness and carbohydrate concentration, from dormancy induction until bud burst, were investigated in populations of two deciduous (quercus robur l. and quercus pubescens willd.) and one evergreen (quercus ilex l.) european oak. mean cold hardiness values in january were -56, -45 and -27 degrees c for q. robur, q. pub ... | 2007 | 17331900 |
| leaf traits and tree rings suggest different water-use and carbon assimilation strategies by two co-occurring quercus species in a mediterranean mixed-forest stand in tuscany, italy. | we compared the water-use characteristics of co-occurring mature quercus cerris l. and quercus pubescens willd. trees growing in resource-limited (mainly water) hilly habitats in tuscany, italy. the species differed in their distribution along soil water gradients and in their access to, and use of, water, even though the study year was wetter than average, though with a summer drought. compared with q. cerris, q. pubescens had greater access to soil water (less negative predawn water potentials ... | 2007 | 17938105 |
| persisting soil drought reduces leaf specific conductivity in scots pine (pinus sylvestris) and pubescent oak (quercus pubescens). | leaf specific conductivity (lsc; the ratio of stem conductivity (k(p)) to leaf area (a(l))), a measure of the hydraulic capacity of the stem to supply leaves with water, varies with soil water content. empirical evidence for lsc responses to drought is ambiguous, because previously published results were subject to many confounding factors. we tested how lsc of similar-sized trees of the same population, under similar climatic conditions, responds to persistently wet or dry soil. scots pine (pin ... | 2008 | 18244940 |
| ultrasonic acoustic emissions in drought-stressed trees--more than signals from cavitation? | ultrasonic acoustic emission (uae) in trees is often related to collapsing water columns in the flow path as a result of tensions that are too strong (cavitation). however, in a decibel (db) range below that associated with cavitation, a close relationship was found between uae intensities and stem radius changes. uae was continuously recorded on the stems of mature field-grown trees of scots pine (pinus sylvestris) and pubescent oak (quercus pubescens) at a dry inner-alpine site in switzerland ... | 2008 | 18540974 |
| a method to quantify transesterification activities of lipases in litters. | lipases are glycerol ester hydrolases (ec 3.1.1.3) produced by a wide range of microorganisms. they catalyse the hydrolysis of different esters but this reaction is reversible, depending on the water content of the reaction medium, via esterification and transesterification. the synthetic activity of lipases can be of major importance in natural ecosystems since it can be involved in carbon stockage in soils or litters. here, the detection of transesterification activities of lipases in litter i ... | 2009 | 19426767 |
| drought-induced adaptation of the xylem in scots pine and pubescent oak. | drought impairs tree growth in the inner-alpine valleys of central europe. we investigated species-specific responses to contrasting water supply, with scots pine (pinus sylvestris l.), threatened by drought-induced mortality, and pubescent oak (quercus pubescens willd.), showing no connection between drought events and mortality. the two co-occurring tree species were compared, growing either along an open water channel or at a site with naturally dry conditions. in addition, the growth respons ... | 2009 | 19483185 |
| natural hybridisation between quercus petraea (matt.) liebl. and quercus pubescens willd. within an italian stand as revealed by microsatellite fingerprinting. | interspecific gene flow is frequently reported in the genus quercus. however, interfertile oak species often seem to remain distinct, even within areas of sympatry. this study employed molecular markers to verify, at a fine scale, the presence of interspecific gene flow in a natural population of quercus petraea and quercus pubescens. within a delimited area of 6 ha, all adult trees belonging to the studied oak complex and seeds from a subsample of such trees were collected and analysed using mo ... | 2009 | 19689784 |
| changes in leaf phenology of three european oak species in response to experimental climate change. | *because the phenology of trees is strongly driven by environmental factors such as temperature, climate change has already altered the vegetative and reproductive phenology of many species, especially in the temperate zone. here, we aimed to determine whether projected levels of warming for the upcoming decades will lead to linear changes in the phenology of trees or to more complex responses. *we report the results of a 3-yr common garden experiment designed to study the phenological response ... | 2010 | 20406403 |
| population differentiation of sessile oak at the altitudinal front of migration in the french pyrenees. | to assess the effects of altitude on the level and structure of genetic diversity, a genetic survey was conducted in 12 populations of sessile oak (quercus petraea) located between 130 and 1660 m in two parallel valleys on the northern side of the pyrenees mountains. genetic diversity was monitored at 16 nuclear microsatellite loci and 5 chloroplast dna (cpdna) markers. the cpdna survey suggested that extant populations in both valleys shared the same source populations from the plain. there was ... | 2010 | 20561196 |
| an ethnobotanical survey of medicinal plants in sivrice (elazığ-turkey). | this study aimed to identify wild plants collected for medical purposes by the local people of sivrice county, located in the eastern anatolia region of turkey, and to establish the uses and local names of these plants. | 2010 | 20713142 |
| driving factors of a vegetation shift from scots pine to pubescent oak in dry alpine forests. | an increasing number of studies have reported on forest declines and vegetation shifts triggered by drought. in the swiss rhone valley (valais), one of the driest inner-alpine regions, the species composition in low elevation forests is changing: the sub-boreal scots pine (pinus sylvestris l.) dominating the dry forests is showing high mortality rates. concurrently the sub-mediterranean pubescent oak (quercus pubescens willd.) has locally increased in abundance. however, it remains unclear wheth ... | 2012 | 23504734 |
| species-specific reversal of stem xylem embolism after a prolonged drought correlates to endpoint concentration of soluble sugars. | recent reports on tree mortality associated with anomalous drought and heat have raised interest into processes underlying tree resistance/resilience to water stress. hydraulic failure and carbon starvation have been proposed as main causes of tree decline, with recent theories treating water and carbon metabolism as interconnected processes. we subjected young plants of two native (quercus pubescens [qp] and prunus mahaleb [pm]) and two invasive (robinia pseudoacacia [rp] and ailanthus altissim ... | 2016 | 27174138 |
| seasonal variability of foliar photosynthetic and morphological traits and drought impacts in a mediterranean mixed forest. | the mediterranean region is a hot spot of climate change vulnerable to increased droughts and heat waves. scaling carbon fluxes from leaf to landscape levels is particularly challenging under drought conditions. we aimed to improve the mechanistic understanding of the seasonal acclimation of photosynthesis and morphology in sunlit and shaded leaves of four mediterranean trees (quercus ilex l., pinus halepensis mill., arbutus unedo l. and quercus pubescens willd.) under natural conditions. vc,max ... | 2015 | 25836361 |