Digitalni repozitorij raziskovalnih organizacij Slovenije

Iskanje po repozitoriju
A+ | A- | Pomoč | SLO | ENG

Na voljo sta dva načina iskanja: enostavno in napredno. Enostavno iskanje lahko zajema niz več besed iz naslova, povzetka, ključnih besed, celotnega besedila in avtorja, zaenkrat pa ne omogoča uporabe operatorjev iskanja. Napredno iskanje omogoča omejevanje števila rezultatov iskanja z vnosom iskalnih pojmov različnih kategorij v iskalna okna in uporabo logičnih operatorjev (IN, ALI ter IN NE). V rezultatih iskanja se izpišejo krajši zapisi podatkov o gradivu, ki vsebujejo različne povezave, ki omogočajo vpogled v podroben opis gradiva (povezava iz naslova) ali sprožijo novo iskanje (po avtorjih ali ključnih besedah).

Išči po:

71 - 80 / 500
Na začetekNa prejšnjo stran45678910111213Na naslednjo stranNa konec
Precipitation is not limiting for xylem formation dynamics and vessel development in European beech from two temperate forest sites
Peter Prislan, Katarina Čufar, Martin De Luis, Jožica Gričar, 2018

Povzetek: We investigated the dynamics of xylem differentiation processes and vessel characteristics in Fagus sylvatica L. to evaluate the plasticity of xylem structures under different environmental conditions. In 2008%10, analyses were performed on microcores collected weekly from two temperate sites: Menina planina (1200 m above sea level (a.s.l.)) and Panska reka (400 m a.s.l.). The duration between the onset and end of major cell differentiation steps and vessel characteristics (i.e., density, VD; mean diameter, MVD; mean area, MVA; and theoretic conductivity area, TCA) were analysed in the first and last quarters of the xylem rings, also in respect of local weather conditions (precipitation, temperature). Although the onset, duration and end of xylem formation phases differed between the two sites, the time spans between the successive wood formation phases were similar. Significant differences in MVD, MVA and TCA values were found between the first and last quarters of xylem increment, regardless of the site and year. Vessel density, on the other hand, depended on xylem-ring width and differed significantly between the sites, being about 30% higher at the high elevation site, in beech trees with 54% narrower xylem rings. Vessel density in the first quarter of the xylem ring showed a positive correlation with the onset of cell expansion, whereas a negative correlation of VD with the cessation of cell production was found in the last quarter of xylem increment. This may be explained by year-to-year differences in the timing of cambial reactivation and leaf development, which effect hormonal regulation of radial growth. No significant linkage between intra-annual weather conditions and conduit characteristics was found. It can thus be presumed that precipitation is not a limiting factor for xylem growth and cell differentiation in beech at the two temperate study sites and sites across Europe with similar weather conditions.
DiRROS - Objavljeno: 20.02.2020; Ogledov: 74; Prenosov: 75
URL Celotno besedilo (0,00 KB)

Phenotypic trait variation measured on European genetic trials of Fagus sylvatica L
T. Matthew Robson, Marta Benito Garzón, Gregor Božič, Hojka Kraigher, 2018

Povzetek: We present BeechCOSTe52; a database of European beech (Fagus sylvatica) phenotypic measurements for several traits related to fitness measured in genetic trials planted across Europe. The dataset was compiled and harmonized during the COST-Action E52 (2006%2010), and subsequently cross-validated to ensure consistency of measurement data among trials and provenances. Phenotypic traits (height, diameter at breast height, basal diameter, mortality, phenology of spring bud burst and autumn%leaf discoloration) were recorded in 38 trial sites where 217 provenances covering the entire distribution of European beech were established in two consecutive series (1993/95 and 1996/98). The recorded data refer to 862,095 measurements of the same trees aged from 2 to 15 years old over multiple years. This dataset captures the considerable genetic and phenotypic intra-specific variation present in European beech and should be of interest to researchers from several disciplines including quantitative genetics, ecology, biogeography, macroecology, adaptive management of forests and bioeconomy.
DiRROS - Objavljeno: 20.02.2020; Ogledov: 59; Prenosov: 65
URL Celotno besedilo (0,00 KB)

On the spot : utilization of directional cues in vibrational communication of a stink bug
Janez Prešern, Jernej Polajnar, Maarten De Groot, Maja Zorović, Meta Virant-Doberlet, 2018

Povzetek: Although vibrational signalling is among the most ancient and common forms of communication, many fundamental aspects of this communication channel are still poorly understood. Here, we studied mechanisms underlying orientation towards the source of vibrational signals in the stink bug Nezara viridula (Hemiptera, Pentatomidae), where female vibrational song enables male to locate her on the bean plant. At the junction between the main stem and the leaf stalks, male placed his legs on different sides of the branching and orientation at the branching point was not random. Analyses of signal transmission revealed that only a time delay between the arrival of vibrational wave to receptors located in the legs stretched across the branching was a reliable directional cue underlying orientation, since, unexpectedly, the signal amplitude at the branching point was often higher on the stalk away from the female. The plant and the position of the vibrational source on the plant were the most important factors influencing the unpredictability of the amplitude cue. Determined time delays as short as 0.5%ms resulted in marked changes in interneuron activity and the decision model suggests that the behavioural threshold is in the range between 0.3 and 0.5%ms.
Ključne besede: vibrational signals, communications, analyses of signal transmission
DiRROS - Objavljeno: 20.02.2020; Ogledov: 98; Prenosov: 89
URL Celotno besedilo (0,00 KB)

Modelling spatial patterns of correlations between concentrations of heavy metals in mosses and atmospheric deposition in 2010 across Europe
Stefan Nickel, Winfried Schröder, Roman Schmalfuß, Maike Saathoff, Harry Harmens, Gina Mills, Marina V. Frontasyeva, Lambe Barandovski, Oleg Blum, Alejo Carballeira, Zvonka Jeran, Mitja Skudnik, 2018

Povzetek: Background This paper aims to investigate the correlations between the concentrations of nine heavy metals in moss and atmospheric deposition within ecological land classes covering Europe. Additionally, it is examined to what extent the statistical relations are affected by the land use around the moss sampling sites. Based on moss data collected in 2010/2011 throughout Europe and data on total atmospheric deposition modelled by two chemical transport models (EMEP MSC-E, LOTOS-EUROS), correlation coefficients between concentrations of heavy metals in moss and in modelled atmospheric deposition were specified for spatial subsamples defined by ecological land classes of Europe (ELCE) as a spatial reference system. Linear discriminant analysis (LDA) and logistic regression (LR) were then used to separate moss sampling sites regarding their contribution to the strength of correlation considering the areal percentage of urban, agricultural and forestry land use around the sampling location. After verification LDA models by LR, LDA models were used to transform spatial information on the land use to maps of potential correlation levels, applicable for future network planning in the European Moss Survey. Results Correlations between concentrations of heavy metals in moss and in modelled atmospheric deposition were found to be specific for elements and ELCE units. Land use around the sampling sites mainly influences the correlation level. Small radiuses around the sampling sites examined (5 km) are more relevant for Cd, Cu, Ni, and Zn, while the areal percentage of urban and agricultural land use within large radiuses (75%100 km) is more relevant for As, Cr, Hg, Pb, and V. Most valid LDA models pattern with error rates of <40 were found for As, Cr, Cu, Hg, Pb, and V. Land use-dependent predictions of spatial patterns split up Europe into investigation areas revealing potentially high (=above-average) or low (=below-average) correlation coefficients. Conclusions LDA is an eligible method identifying and ranking boundary conditions of correlations between atmospheric deposition and respective concentrations of heavy metals in moss and related mapping considering the influence of the land use around moss sampling sites.
Ključne besede: biomonitoring, chemical transport models, correlation analysis, ecological classification, linear discriminant analysis, logistic regression
DiRROS - Objavljeno: 20.02.2020; Ogledov: 112; Prenosov: 88
URL Celotno besedilo (0,00 KB)

Manipulative experiments demonstrate how long-term soil moisture changes alter controls of plant water use
Charlotte Grossiord, Sanna Sevanto, Jean-Marc Limousin, Patrick Meir, Maurizio Mencuccini, Robert E. Pangle, William T. Pockman, Yann Salmond, Roman Zweifel, Nate G. McDowell, 2018

Povzetek: Tree transpiration depends on biotic and abiotic factors that might change in the future, including precipitation and soil moisture status. Although short-term sap flux responses to soil moisture and evaporative demand have been the subject of attention before, the relative sensitivity of sap flux to these two factors under long-term changes in soil moisture conditions has rarely been determined experimentally. We tested how long-term artificial change in soil moisture affects the sensitivity of tree-level sap flux to daily atmospheric vapor pressure deficit (VPD) and soil moisture variations, and the generality of these effects across forest types and environments using four manipulative sites in mature forests. Exposure to relatively long-term (two to six years) soil moisture reduction decreases tree sap flux sensitivity to daily VPD and relative extractable water (REW) variations, leading to lower sap flux even under high soil moisture and optimal VPD. Inversely, trees subjected to long-term irrigation showed a significant increase in their sensitivity to daily VPD and REW, but only at the most water-limited site. The ratio between the relative change in soil moisture manipulation and the relative change in sap flux sensitivity to VPD and REW variations was similar across sites suggesting common adjustment mechanisms to long-term soil moisture status across environments for evergreen tree species. Overall, our results show that long-term changes in soil water availability, and subsequent adjustments to these novel conditions, could play a critical and increasingly important role in controlling forest water use in the future.
Ključne besede: acclimation, climate change, drought, Irrigation, vapor pressure deficit, water use
DiRROS - Objavljeno: 20.02.2020; Ogledov: 111; Prenosov: 229
URL Celotno besedilo (0,00 KB)

Lead concentrations and stable lead isotope ratios in moss in Slovenia and Switzerland
Elvira Schnyder, Marko Štrok, Zaida Kosonen, Mitja Skudnik, Darja Mazej, Zvonka Jeran, Lotti Thöni, 2018

Povzetek: Using moss as a biomonitor is an established technique for monitoring atmospheric deposition of trace elements, including lead (Pb), a metal that is toxic for most organisms. Lead enters the environment during production and combustion processes and during the use of leaded gasoline. There are four stable isotopes of Pb, and the isotopic composition can be used to determine sources and pathways of atmospheric Pb pollution. In this study we determined Pb concentrations and isotope ratios in moss (Hypnum cupressiforme and Pleurozium schreberi) collected from 1990 to 2015 in Switzerland and from 2006 to 2015 in Slovenia. We used microwave sample digestion and inductively coupled plasma mass spectrometry (ICP-MS) for Pb concentrations and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) for Pb isotope ratio determination. The aim was to assess the change in atmospheric Pb deposition over time and the differences between and within the two countries. Additionally, we assessed the current Pb isotope ratios for both countries and evaluated the change over time in Switzerland. The Pb concentration in moss decreased significantly over time in both countries. In 2015, at the end of the study period, concentrations were significantly higher in Slovenia compared to in Switzerland. Higher Pb concentrations in Slovenia may be related to the prolonged use of leaded gasoline or to the larger influence of industrial sources. Within Switzerland Pb concentrations differed significantly between regions. These differences are likely a consequence of different population densities and precipitation amounts. In Slovenia there were no significant differences between the regions, indicating that there are no large differences in Pb emissions. The 206Pb/207Pb and 208Pb/206Pb isotope ratios differed between Slovenia and Switzerland and between some regions within Switzerland. This finding shows that Slovenia and Switzerland, as well as the different regions within Switzerland, are influenced by different Pb sources. In Switzerland, 206Pb/207Pb increased and 208Pb/206Pb decreased over time and shifted away from the isotopic signature of leaded gasoline. Additionally, both isotope ratios became more homogeneous within Switzerland, which suggests that the sources of Pb became more similar. Overall, the Pb isotope ratios reflect the diminishing influence of leaded gasoline and indicate an increasing importance of industry, coal burning and natural bedrock as Pb sources.
Ključne besede: lead (Pb) deposition, moss biomonitoring, regional differences, temporal trends, Europe
DiRROS - Objavljeno: 20.02.2020; Ogledov: 103; Prenosov: 65
URL Celotno besedilo (0,00 KB)

Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought
Marceau Guérin, Dario Martin-Benito, Georg von Arx, Laia Andreu-Hayles, Kevin L. Griffin, Rayann Hamdan, Nate G. McDowell, Robert Muscarella, William T. Pockman, Pierre Gentine, 2018

Povzetek: In the southwestern USA, recent large-scale die-offs of conifers raise the question of their resilience and mortality under droughts. To date, little is known about the interannual structural response to droughts. We hypothesized that piñon pines (Pinus edulis) respond to drought by reducing the drop of leaf water potential in branches from year to year through needle morphological adjustments. We tested our hypothesis using a 7-year experiment in central New Mexico with three watering treatments (irrigated, normal, and rain exclusion). We analyzed how variation in %evaporative structure% (needle length, stomatal diameter, stomatal density, stomatal conductance) responded to watering treatment and interannual climate variability. We further analyzed annual functional adjustments by comparing yearly addition of needle area (LA) with yearly addition of sapwood area (SA) and distance to tip (d), defining the yearly ratios SA:LA and SA:LA/d. Needle length (l) increased with increasing winter and monsoon water supply, and showed more interannual variability when the soil was drier. Stomatal density increased with dryness, while stomatal diameter was reduced. As a result, anatomical maximal stomatal conductance was relatively invariant across treatments. SA:LA and SA:LA/d showed significant differences across treatments and contrary to our expectation were lower with reduced water input. Within average precipitation ranges, the response of these ratios to soil moisture was similar across treatments. However, when extreme soil drought was combined with high VPD, needle length, SA:LA and SA:LA/d became highly nonlinear, emphasizing the existence of a response threshold of combined high VPD and dry soil conditions. In new branch tissues, the response of annual functional ratios to water stress was immediate (same year) and does not attempt to reduce the drop of water potential. We suggest that unfavorable evaporative structural response to drought is compensated by dynamic stomatal control to maximize photosynthesis rates.
Ključne besede: functional ratio, Huber value, leaf area, conductance, xylem
DiRROS - Objavljeno: 20.02.2020; Ogledov: 83; Prenosov: 57
URL Celotno besedilo (0,00 KB)

Iskanje izvedeno v 0 sek.
Na vrh