Search results for "WOOD"

The microscopic theory of diffusion-controlled defect aggregation

1998

Abstract The kinetics of diffusion-controlled aggregation of primary Frenkel defects ( F and H centers) in irradiated CaF 2 crystals is theoretically studied. Microscopic theory is based on the discrete-lattice formalism for the single defect densities (concentrations) and the coupled joint densities of similar and dissimilar defects treated in terms of the Kirkwood superposition approximation. Conditions and dynamics of the efficient F center aggregation during crystal heating after irradiation are analyzed.

Revising midlatitude summer temperatures back to A.D. 600 based on a wood density network

2015

Annually resolved and millennium-long reconstructions of large-scale temperature variability are primarily composed of tree ring width (TRW) chronologies. Changes in ring width, however, have recently been shown to bias the ratio between low- and high-frequency signals. To overcome limitations in capturing the full spectrum of past temperature variability, we present a network of 15 maximum latewood density (MXD) chronologies distributed across the Northern Hemisphere extratropics. Independent subsets of continental-scale records consistently reveal high MXD before 1580 and after 1910, with below average values between these periods. Reconstructed extratropical summer temperatures reflect n…

In vitro propagation ofSalix tarraconensis Pau ex Font Quer, an endemic and threatened plant

1996

Salix tarraconensis Pau ex Font Quer, an endemic willow species from northeast Spain, was micropropagated with nodal segments. Shoot multiplication was obtained with different cytokinins, either on Murashige and Skoog medium or woody plant medium. Best results for shoot formation were obtained on Murashige and Skoog medium containing 4.9 μM of 6-γ-γ-dimethylallylaminopurine. Shoots showed strong apical dominance, and some cultures displayed apical necrosis. Benzyladenine gave the worst results; shoots displayed very slow growth, deformed leaves, and hyperhydrity. Good rooting of shoots was obtained with different auxins or without plant growth regulators on woody plant medium. The best resu…

Ecological study of the wood mouse helminth community in a burned Mediterranean ecosystem in regeneration five years after a wildfire

2007

AbstractParasites are used as biological tags in environmental impact studies. However, terrestrial systems in general and small mammals in particular are rarely considered in these ecological studies. Based on the effects of a wildfire which occurred in the Spanish Serra Calderona Natural Park — a typical Mediterranean ecosystem — the regeneration process of the wood mouse population and its helminth community is analysed. A total of 217 individuals of Apodemus sylvaticus were studied in a five year period, from the second to the fifth post-fire year: 152 mice originating from the burned area and 65 from the control — non-burned — area. The helminth community for both burned and non-burned…

Quantifying the Indicator Power of an Indicator Species

2009

Biodiversity indicator species are needed for classifying biotopes and sites for conservation, and a number of methods have been developed for determining indicator species for this purpose. Nevertheless, in addition to site classification, there is sometimes a need to define an indicator species that indicates the occurrence of another species. For example, when a species of interest (target species) is difficult to detect or identify, a reliable indicator species can function as a tool that saves time and money. We derived a method that provides a quantitative measure of the indicator power (IP) of an indicator species for the target species or any species assemblage. We calculated the me…

Macrobotanical evidence (wood charcoal and seeds) from the Middle Palaeolithic site of El Salt, Eastern Iberia: Palaeoenvironmental data and plant re…

2018

Despite the current growing number of studies that focus on macrobotanical remains from Middle Palaeolithiccontexts, plant use among hunter-gatherer societies remains unknown in many regions of Europe. Large-scaleflotation of archaeological sediments has made it possible to recover a large amount of plant remains (fruits,seeds and wood) from units VIII, IX, Xa and Xb at El Salt, Eastern Iberia (49.2–52.3 ka BP). The combination ofanthracological and carpological analyses has provided a more accurate picture of the Middle Palaeolithiclandscape in the Serpis valley, as well as significant information about other possible uses of plants, not only asfuel, but for woodworking or food, for instan…

Predicting stiffness and strength of birch pulp:Polylactic acid composites

2016

This paper studies failure of birch pulp–polylactic acid composites. Stiffness and strength are calculated using the theory of short fibre composites and the results are compared to experimental data. The results differed from the experimental values by 0–6%. With less aligned fibres the short fibre theory is not feasible. The performance of the 40 wt% birch pulp – polylactic acid composite is predicted with X-ray microtomography based finite element modelling, and the results are compared with experiments. Stiffness results differed from experiments by 1–17% . By adding into the models a third material phase representing the interface between the fibres and the matrix, the stress–strain c…

Plants in the UK flower a month earlier under recent warming.

2022

Global temperatures are rising at an unprecedented rate, but environmental responses are often difficult to recognize and quantify. Long-term observations of plant phenology, the annually recurring sequence of plant developmental stages, can provide sensitive measures of climate change and important information for ecosystem services. Here, we present 419 354 recordings of the first flowering date from 406 plant species in the UK between 1753 and 2019 CE. Community-wide first flowering advanced by almost one month on average when comparing all observations before and after 1986 ( p < 0.0001). The mean first flowering time is 6 days earlier in southern than northern sites, 5 days earlier…

He kept us out of war? : yleisen mielipiteen vaikutus Woodrow Wilsonin päätöksiin Yhdysvaltain liittymisestä ensimmäiseen maailmansotaan

2003

Wood-inhabiting fungi with tight associations with other species have declined as a response to forest management

2017

Research on mutualistic and antagonistic networks, such as plant-pollinator and host-parasite networks, has shown that species interactions can influence and be influenced by the responses of species to environmental perturbations. Here we examine whether results obtained for directly observable networks generalize to more complex networks in which species interactions cannot be observed directly. As a case study, we consider data on the occurrences of 98 wood-inhabiting fungal species in managed and natural forests. We specifically ask if and how much the positions of wood-inhabiting fungal species within the interaction networks influence their responses to forest management. For this, we…