Search results for "dial"
showing 10 items of 4830 documents
Caribbean hydroclimate and vegetation history across the last glacial period
2019
Abstract We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydro…
Human occupation and environmental change in the western Maghreb during the Last Glacial Maximum (LGM) and the Late Glacial. New evidence from the Ib…
2019
With the onset of the Last Glacial Maximum (LGM), hunter-gatherers of the so-called Iberomaurusian techno-complex appeared in what is now the Mediterranean Maghreb. During a period of about seven thousand years, these groups left sandy occupation layers in a limited number of archaeological sites, while at the beginning of Greenland Interstadial (GI) 1, the sudden shift towards the deposition of shell-rich sediments and the increase in number of sites document clear changes in subsistence strategies as well as occupation density. It is highly likely that these shifts in human behaviour are related to paleoenvironmental changes in the area, which, so far, are poorly documented in geological …
The ELSA-Flood-Stack: A reconstruction from the laminated sediments of Eifel maar structures during the last 60 000 years
2016
Abstract This study reconstructs the main flood phases in central Europe from event layers in sediment cores from Holocene Eifel maar lakes and Pleistocene dry maar structures. These reconstructions are combined with recent gauge time-series to cover the entire precipitation extremes of the last 60 000 years. In general, Eifel maar sediments are perfectly suited for the preservation of event layers since the deep water in the maar lakes is seasonal anoxic and therefore, bioturbation is low. However, the preservation of annual lamination is only preserved in Holzmaar and Ulmener Maar; the other cores are dated by 14C, magnetostratigraphy, tephra markers and ice core tuning. The cores were dr…
Iberian Neolithic Networks: The Rise and Fall of the Cardial World
2017
Recent approaches have described the evolutionary dynamics of the first Neolithic societies as a cycle of rise and fall. Several authors, using mainly c14 dates as a demographic proxy, identified a general pattern of a boom in population coincident with the arrival of food production economies followed by a rapid decline some centuries afterwards in multiple European regions. Concerning Iberia, we also noted that this phenomenon correlates with an initial development of archaeological entities (i.e., ‘cultures’) over large areas (e.g. the Impresso-Cardial in West Mediterranean), followed by a phase of ‘cultural fragmentation’ by the end of Early Neolithic. These results in a picture of high…
The Bonobo-DialiumPositive Interactions: Seed Dispersal Mutualism
2013
A positive interaction is any interaction between individuals of the same or different species (mutualism) that provides a benefit to both partners such as increased fitness. Here we focus on seed dispersal mutualism between an animal (bonobo, Pan paniscus) and a plant (velvet tamarind trees, Dialium spp.). In the LuiKotale rainforest southwest of Salonga National Park, Democratic Republic of Congo, seven species of the genus Dialium account for 29.3% of all trees. Dialium is thus the dominant genus in this forest. Dialium fruits make up a large proportion of the diet of a habituated bonobo community in this forest. During the 6 months of the fruiting season, more than half of the bonobos' …
Biology and Behaviour of Cirrospilus diallus and Cirrospilus pictus, Parasitoids of Phyllocnistis citrella
2005
International audience; Studies were carried out on some biological and behavioral aspects of Cirrospilus diallus Walker and Cirrospilus pictus (Nees) (Hymenoptera: Eulophidae) in relation to their host, the citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Adults of both species fed with sugar lived on average 4.45 +/- 0.19 days, whereas adults provided with honey survived on average 40.62 +/- 1.97 days. Rates of host mortality due to parasitoid stings without oviposition were as high as 31.25 and 37.73% for C. pictus and C. diallus, respectively. Both species showed arrhenotokous parthenogenesis. Sex ratios of parasitoids emerging from the 2nd and 3rd …
Artificial germination activation of Dialium corbisieri by imitation of ecological process.
2013
11 pages; International audience; Species of the gender Dialium commonly are trees found in Central African rainforests. They produce tasty sugary fruits, feeding numerous frugivores, but are, despite their valuable nutritional value, rarely exploited by humans. A potential reason for this could be the complexity of symbiotic dependence between trees and pollinators, germination activators, and dispersers causing problems in ancestral and contemporary domestication. We investigated Dialium corbisieri reproduction in the Democratic Republic of the Congo, Bandundu Province. Here we give a key for an artificial activation of germination of these trees ecologically adapted to the digestive syst…
Controversy over the Mode of Growth of Cambial Cylinder
2021
Based on mathematical modelling, this review article describes the mechanism of expansion in the circumference of vascular cambium due to radial growth leading to increase in the tree-trunk diameter, and emphasizes upon the huge difference in the rate of symplastic growth of cambial initials in two different directions, viz. radial and circumferential. On the basis of anatomical evidence regarding the role of symplastic and intrusive growths, the long-standing hypothesis that the intrusive growth contributes to the increase of cambium circumference has been falsified. It has been shown with the help of mathematical calculations as well as anatomical observations that only symplastic growth …
Corsican Pine (Pinus laricio Poiret) Stand Management: Medium and Long Lasting Effects of Thinning on Biomass Growth
2018
Originally published in Forests: Picchio R, Venanzi R, Latterini F, Marchi E, Laschi A, Lo Monaco A (2018). Corsican pine (Pinus laricio Poiret) stand management: medium and long lasting effects of thinning on biomass growth. Forests 9 (5), article number 257, p. 1-17 (open access) DOI: 10.3390/f9050257 This article can be downloaded at: https://www.mdpi.com/1999-4907/9/5/257 Abstract With the aim of acquiring better comprehension of the ecological and productive aspects of the management of pine forests, we monitored logging damage and evaluated the effects of thinning on stand growth 20 years after the treatment in a Pinus laricio Poiret stand in central Italy. The objectives of the p…
Rays hamper intrusive growth of vessel elements
2021
Key message In some circumstances vessel elements, both broad and narrow, enlarge only symplastically in tangential direction. Rays play a special role in regulating intrusive enlargement of vessel elements. Abstract The aim of this study was to analyse relations occurring between vessel elements and surrounding cells, i.e. susceptibility to separation of walls of cells occurring in the vicinity of vessel elements, with regard to their type—cells of the axial/radial system. On the basis of separation/lack of separation of cell walls, and thus change in cell contacts/lack of change in cell contacts, we have estimated the contribution of particular types of growth—intrusive and symplastic—in …