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21.
Low growth resilience to drought is related to future mortality risk in trees
Lucía De Soto, Maxime Cailleret, Frank Sterck, Steven Jansen, Koen Kramer, Elisabeth M.R. Robert, Tuomas Aakala, Mariano M. Amoroso, Christof Bigler, Jesus Julio Camarero, Katarina Čufar, Tom Levanič, 2020

Povzetek: Severe droughts have the potential to reduce forest productivity and trigger tree mortality. Most trees face several drought events during their life and therefore resilience to dry conditions might be crucial to long-term survival. We assess how growth resilience to severe droughts, including its components resistance and recovery, is related to the ability to survive future droughts by using a tree-ring database of surviving and now-dead trees from 118 sites (22 species, >3,500 trees). We find that, across the variety of regions and species sampled, trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. In angiosperms, drought-related mortality risk is associated with lower resistance (low capacity to reduce impact of the initial drought), while it is related to reduced recovery (low capacity to attain pre-drought growth rates) in gymnosperms. The different resilience strategies in these two taxonomic groups open new avenues to improve our understanding and prediction of drought-induced mortality. Resilience to drought is crucial for tree survival under climate change. Here, DeSoto et al. show that trees that died during drought were less resilient to previous dry events compared to surviving conspecifics, but the resilience strategies differ between angiosperms and gymnosperms.
Ključne besede: trees, mortality, gymnosperms, angiosperms, drought, resilience, resistance, recovery
DiRROS - Objavljeno: 20.02.2020; Ogledov: 1064; Prenosov: 712
URL Celotno besedilo (0,00 KB)

22.
Dendrokronološke raziskave na Založnici - najmlajši znani bakrenodobni koliščarski naselbini na Ljubljanskem barju
Katarina Čufar, Anton Velušček, 2003

Povzetek: Predstavljamo rezultate raziskav lesa in drugih arheoloških najdb z zaščitnih izkopavanj v jarkih na ostankih bakrenodobne-eneolitske koliščarske naselbine Založnica pri Kamniku pod Krimom na Ljubljanskem barju. Od 1315 vzorcev lesa smo jih dendrokronološko raziskali 35%. Sestavili smo dve jesenovi (Fraxinus sp.) in eno hrastovo (Quercus sp.) kronologijo širin branik. Rekonstruirali smo gradbene aktivnosti na naselbini, ki so trajale 90 let. Ugotovili smo, da so se časovno prepletale z aktivnostmi na 10 km oddaljeni naselbini Parte, ki je obstajala istočasno. Na osnovi radiokarbonskih datacij konec gradbenih aktivnosti na Založnici datiramo v 25. stoletje pr. Kr. Naselbina v zadnjih 40 letih obstoja tvori najmlajšo znano eneolitsko koliščarsko naselbino na Ljubljanskem barju in v Sloveniji. Na podlagi datiranega lesa in primerjave drugih arheoloških najdb utemeljujemo uvrstitev naselbine v kulturo Somogyvár-Vinkovci, kar je novost pri interpretaciji poselitvenih sprememb pred nastopom bronaste dobe na območju Ljubljanskega barja, Slovenije in sosednjih dežel.
Ključne besede: kolišča, Ljubljansko barje, bakrena doba, arheologija, radiokarbonsko datiranje, dendrokronologija, arheološki les, hrast, jesen (drevo)
DiRROS - Objavljeno: 17.11.2020; Ogledov: 599; Prenosov: 199
.pdf Celotno besedilo (770,35 KB)

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Transition dates from earlywood to latewood and early phloem to late phloem in Norway Spruce
Jožica Gričar, Katarina Čufar, Klemen Eler, Vladimir Gryc, Hanuš Vavrčík, Martin De Luis, Peter Prislan, 2021

Povzetek: Climate change will affect radial growth patterns of trees, which will result in different forest productivity, wood properties, and timber quality. While many studies have been published on xylem phenology and anatomy lately, little is known about the phenology of earlywood and latewood formation, also in relation to cambial phenology. Even less information is available for phloem. Here, we examined year%to%year variability of the transition dates from earlywood to latewood and from early phloem to late phloem in Norway spruce (Picea abies) from three temperate sites, two in Slovenia and one in the Czech Republic. Data on xylem and phloem formation were collected during 2009%2011. Sensitivity analysis was performed to determine the specific contribution of growth rate and duration on wood and phloem production, separately for early and late formed parts. We found significant differences in the transition date from earlywood to latewood between the selected sites, but not between growth seasons in trees from the same site. It occurred in the first week of July at PAN and MEN and more than two weeks later at RAJ. The duration of earlywood formation was longer than that of latewood formation; from 31.4 days at PAN to 61.3 days at RAJ. In phloem, we found differences in transition date from early phloem to late phloem also between the analysed growth seasons; from 2.5 weeks at PAN to 4 weeks at RAJ Compared to the transition from earlywood to latewood the transition from early phloem to late phloem occurred 25%64 days earlier. There was no significant relationship between the onset of cambial cell production and the transition dates. The findings are important to better understand the inter%annual variability of these phenological events in spruce from three contrasting temperate sites, and how it is reflected in xylem and phloem anatomy.
Ključne besede: Picea abies, xylem formation, phloem formation, cambium, tracheid, sieve cell, conifer, temperate environment
DiRROS - Objavljeno: 22.03.2021; Ogledov: 504; Prenosov: 364
.pdf Celotno besedilo (1,27 MB)

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