Search results for "Abundance"

The Gaia-ESO Survey: The origin and evolution of s-process elements

2018

Context. Several works have found an increase of the abundances of the s-process neutron-capture elements in the youngest Galactic stellar populations. These trends provide important constraints on stellar and Galactic evolution and they need to be confirmed with large and statistically significant samples of stars spanning wide age and distance intervals. Aims. We aim to trace the abundance patterns and the time evolution of five s-process elements - two belonging to the first peak, Y and Zr, and three belonging to the second peak, Ba, La, and Ce - using the Gaia-ESO IDR5 results for open clusters and disc stars. Methods. From the UVES spectra of cluster member stars, we determined the ave…

How livestock grazing affects vegetation structures and small mammal distribution in the semi-arid Karoo

2000

In this study we investigated vegetation changes superimposed by grazing and their effect on small mammals in the Karoo (South Africa) on grazed farmland and an adjacent, 10-year livestock enclosure. Plains and drainage line habitats were compared by monitoring vegetation height and cover, and small mammal species composition and abundance along transects. Animals were captured by live trapping. Vegetation cover was low on the grazed compared to the ungrazed study site, but vegetation height did not differ. The number of small mammal individuals and the number of species captured was higher at the ungrazed study site. Two species of climbing rodents captured in the ungrazed drainage line we…

A Methodology to Derive Global Maps of Leaf Traits Using Remote Sensing and Climate Data

2018

This paper introduces a modular processing chain to derive global high-resolution maps of leaf traits. In particular, we present global maps at 500 m resolution of specific leaf area, leaf dry matter content, leaf nitrogen and phosphorus content per dry mass, and leaf nitrogen/phosphorus ratio. The processing chain exploits machine learning techniques along with optical remote sensing data (MODIS/Landsat) and climate data for gap filling and up-scaling of in-situ measured leaf traits. The chain first uses random forests regression with surrogates to fill gaps in the database (> 45% of missing entries) and maximizes the global representativeness of the trait dataset. Plant species are then a…

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

2021

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ec…

Helminth communities of herons (Aves: Ardeidae) in southern Italy

2016

The helminth communities of nine species of herons from southern Italy were studied and compared. Of 24 taxa found including seven digeneans, seven nematodes, six cestodes and four acanthocephalans, only five taxa were found in more than one heron species, and five of the 21 taxa that could be identified to species level were classified as 'heron specialists'. The total number of helminth species per heron species ranged from 1 in Botaurus stellaris to 9 in Ixobrychus minutus with infection levels generally low. A statistical comparison was carried out for herons with a sample size >. 5. At the infracommunity level, only I. minutus clearly differed from other heron species. Diversity parame…

The influence of environmental factors on abundance and prevalence of a commensal ostracod hosted by an invasive crayfish: are ‘parasite rules’ relev…

2014

Summary Symbiosis represents a widespread and successful lifestyle, but research on symbiotic associations has been mainly focused on parasites. Three general patterns in parasite ecology have been proposed: (i) aggregation, (ii) positive and tight correlation between mean symbiont abundance and its variance and (iii) positive correlation between abundance and prevalence of symbionts. The factors affecting abundance and prevalence within symbiont species can be grouped into host features and environmental conditions. According to research in parasite ecology, environmental conditions seem to play a minor role. We investigated whether the three most recognised parasite patterns were also evi…

Distribution patterns of epiphytic reed-associated macroinvertebrate communities across European shallow lakes

2021

So far, research on plant-associated macroinvertebrates, even if conducted on a large number of water bodies, has mostly focused on a relatively small area, permitting limited conclusions to be drawn regarding potentially broader geographic effects, including climate. Some recent studies have shown that the composition of epiphytic communities may differ considerably among climatic zones. To assess this phenomenon, we studied macroinvertebrates associated with the common reed Phragmites australis (Cav.) Trin. ex Steud in 46 shallow lakes using a common protocol. The lakes, located in nine countries, covered almost the entire European latitudinal range (from <48°N to 61°N) and captured much …

Gestion territoriale des adventices : effets des propriétés du paysage sur les communautés adventices et sur leur régulation par les carabidae

2015

Landscape-scale management is known to affect pest and biodiversity levels in agroecosystems. Here, we focus on the lanscape drivers of arable weeds, first by reviewing evidence of direct landscape effects on weed species richness and abundance and then by analyzing current knowledge on landscape effects on carabids, which are well-known weed seed predators that contribute to the biological regulation of weeds. Our analysis shows that (i) heterogeneous landscapes usually harbor higher species richness and more diversified communities than simple ones, (ii) total weed and carabid abundances appear seldomly affected by the landscape context of arable fields and (iii) weed seed predation in fi…

2021

Abstract. Lignin oxidation products (LOPs) are widely used as vegetation proxies in climate archives, such as sediment and peat cores. The total LOP concentration, Σ 8, provides information on the abundance of vegetation, while the ratios C / V and S / V of the different LOP groups also provide information on the type of vegetation. Recently, LOP analysis has been successfully applied to speleothem archives. However, there are many open questions concerning the transport and microbial degradation of LOPs on their way from the soil into the cave system. These processes could potentially alter the original source-dependent LOP signals, in particular the C / V and S / V ratios, and thus compli…

Pseudolillia Maubeuge, 1949 (Ammonitida, Hildoceratidae) in the Lower Jurassic (Toarcian) of the NE Spain

2017

In the present paper, 147 specimens assigned to the genus Pseudolillia Maubeuge, 1949 are studied. This is a considerably high number of samples in comparison with those known in other geographical areas where they have been cited, such as northern France, the Pyrenees, the Betic Range, Morocco, Portugal, Italy, Hungary and Bulgaria. The six taxa described, P. murvillensis, P. hispanica, P. emiliana, P. donovani, Pseudolillia ? n. sp. (en García-Gómez & Rivas, 1980), and Pseudolillia ? sp., come from 22 sites in the Cantabrian and Iberian Ranges and the Isle of Majorca. Their presence in expanded sections enabled us to situate the stratigraphic position of the genus between the upper part o…