Search results for "conservation."
showing 10 items of 1994 documents
Allium albanicum (Amaryllidaceae), a new species from Balkans and its relationships with A. meteoricum Heldr. & Hausskn. ex Halácsy
2019
A new species, Alliumalbanicum, is described and illustrated from Albania (Balkan Peninsula). It grows on serpentines or limestone in open rocky stands with a scattered distribution, mainly in mountain locations. Previously, the populations of this geophyte were attributed to A.meteoricum Heldr. & Hausskn. ex Halácsy, described from a few localities of North and Central Greece. These two species indeed show close relationships, chiefly regarding some features of the spathe valves, inflorescence and floral parts. They also share the same diploid chromosome number 2n =16 and similar karyotype, while seed testa micro-sculptures and leaf anatomy reveal remarkable differences. There are …
A new polyploid species of Limonium (Plumbaginaceae) from the Western Mediterranean basin
2015
A new species of Plumbaginaceae, Limonium irtaensis, is described and illustrated from the Western Mediterranean basin (Iberian Peninsula). The new species is triploid (2n = 26) and shows a papillate stigma and pollen with a fine reticulate exine (B type). A detailed morphological description is given, and its main diagnostic characters are compared with the related species. Conservation status has been assessed according to the IUCN protocol.
An analysis of botanical studies of vascular plants from Italian wetlands
2022
Wetlands are essential for life on Earth, but at the same time the most threatened environments due to the gradual alterations associated with climate change and human action. The botanical studies on wetland higher plants carried out in Italy from 1950 until today are analysed in this survey. The 1,265 contributions resulting from this study are analysed from a historical, geographical, and content point of view. Most of the scientific contributions were published in the 1980s and 1990s, often by the same research groups and on a local scale. The predominant research theme is the inventory. Most papers are mainly focused on lakes and rivers. The results of this literature survey point to t…
A Numerical Approach to Finite Journal Bearings Lubricated With Ferrofluid
1987
Several cases of cylindrical bearings lubricated with ferrofluid are examined by means of a finite-difference numerical procedure. The subregion of cavitation is determined by imposing mass conservation across the “rupture” and “reformation” boundaries of the complete film. The examined cases refer to bearings confined by sealing rings formed by the lubricant itself, for which there is no need of external supply. In each case the most significant parameters are calculated and it is possible to see that the use of these bearings is favorable when speeds are low, clearances large, and loads light, because in such conditions the magnetic effects are comparable with the pure hydrodynamic ones a…
Restoration of the Northeast cloister of the Convento de la Compañía de Jesús in Antigua, Guatemala
1998
[EN] The extraordinary history of the foundation, destruction and survival of La Antigua in Guatemala, a city frozen in time over two centuries ago, is the background for the introduction of the history of the Convento de la CompañÌa de Jesús and its northeast cloister, which has recently been restored and whose surrounding buildings have been refurbished to house the headquarters of the Institute of Ibero-American Cooperation in the city.
The influence of land use on the genetic structure of populations of the common frog Rana temporaria
1990
In order to find out the influence of land use and topographic distance on the genetic structure of populations of the common frog Rana temporaria L. in the Saar-Palatinate lowlands (Federal Republic of Germany), tissue of larvae was examined by means of horizontal starch gel electrophoresis. A total of 24 loci coding for 14 different enzymes were studied. Genotype frequencies, allele frequencies and mean heterozygosity were calculated, and genetic distances using Nei's formula. Strong deviations from the Hardy-Weinberg equilibrium were found; the degree of homozygosity was higher than expected. Separation by highways reduced average heterozygosity as well as genetic polymorphism of local p…
Exposing the structure of an Arctic food web
2015
15 pages; International audience; How food webs are structured has major implications for their stability and dynamics. While poorly studied to date, arctic food webs are commonly assumed to be simple in structure, with few links per species. If this is the case, then different parts of the web may be weakly connected to each other, with populations and species united by only a low number of links. We provide the first highly resolved description of trophic link structure for a large part of a high-arctic food web. For this purpose, we apply a combination of recent techniques to describing the links between three predator guilds (insectivorous birds, spiders, and lepidopteran parasitoids) a…
The influence of ants on soil and water losses from an orange orchard in eastern Spain
2008
Herbicide applications have greatly reduced plant cover, and increased soil erosion on a new orange orchard planted on valley slopes in eastern Spain. This has increased the importance of soil fauna, such as ants, in regulating soil erosion processes. Ants increase water infiltration rates by forming soil macropores during nest construction, but new soil brought to the surface by ant activity could increase the sediments available for erosion. Simulated rainfall experiments were conducted on 20 paired plots (20 with ant activity and 20 controls) to study the impact of ants on surface water flow and sediment movement in an intensively managed orange orchard near Valencia, Spain. Simulated ra…
An Inventory Approach to the Assessment of Main Traditional Landscapes in Sicily (Central Mediterranean Basin)
2012
EU policy for the conservation of cultural landscapes is of particular importance for a region such as Sicily (Italy) which is the site of many Mediterranean traditional cultural landscapes as well as new landscapes created by contemporary agriculture. Such variety of landscape, however, is not supported or confirmed by specialised inventories that identify and classify the typical Main Traditional Landscape (MTL). On the basis of these considerations, the objective of the present paper is to draw up a preliminary inventory and present a brief characterisation of MTLs in Sicily, in line with the multidisciplinary experiences and approaches implemented at European and national levels. In def…
Ecological specialization to fluctuating resources prevents long-distance migratory raptors from becoming sedentary on islands
2013
[Background]: The adaptive transition between behavioral strategies, such as the shift from migratoriness to sedentariness, remains an outstanding question in evolutionary ecology. Density-dependent variation in the age of first breeding has been proposed as a feasible mechanism through which long-lived migratory birds with deferred sexual maturity should become sedentary to persist on islands. Although this pattern seems to hold for most raptors and herons, a few exceptions have been identified. One of these exceptions is the Eleonora's falcon, a long-distance migratory bird, which shows one of the most peculiar adaptations in the timing of reproduction and food requirements among raptors.…