1,721,180 research outputs found
Trophic ecology of tropical leaf litter ants (Hymenoptera: Formicidae) - a stable isotope study in four types of Bornean rain forest
No full textWe measured delta N-15 values and inferred the trophic positions of 151 ground ant species from four types of rain forests (alluvial, limestone, dipterocarp forest, and Kerangas) in Gunung Mulu National Park, in Sarawak, Malaysia. Four hypotheses were tested: 1) Ground-foraging ants occur in all trophic levels; 2) ant subfamilies differ in their trophic status; 3) delta 15N values differ among species within genera and among genera within subfamilies; and 4) ant assemblages in different forest types differ in their trophic structure. Base-line corrected mean 8 15N values for different ant species ranged from -0.67 parts per thousand to 10.56 parts per thousand thus confirming that forest ants occupy a variety of trophic levels. Based on stable isotopes we distinguished three major trophic groups: a) species mostly feeding on hemipteran exudates and other plant-derived food resources; b) omnivorous species with mixed diet of plant and animal prey; and c) truly predacious species, including arthropod specialists. Ant subfamilies differed significantly in their trophic positions, as did many ant genera within subfamilies and ant species within ant genera. Several ant species exhibited dietary flexibility and differed significantly in trophic positions across forest types.DFG [PF 441 / 3 - 1, PF 441 / 3 - 3]; DAA
Trophic ecology of tropical leaf litter ants (Hymenoptera: Formicidae) - a stable isotope study in four types of Bornean rain forest
No full textWe measured delta N-15 values and inferred the trophic positions of 151 ground ant species from four types of rain forests (alluvial, limestone, dipterocarp forest, and Kerangas) in Gunung Mulu National Park, in Sarawak, Malaysia. Four hypotheses were tested: 1) Ground-foraging ants occur in all trophic levels; 2) ant subfamilies differ in their trophic status; 3) delta 15N values differ among species within genera and among genera within subfamilies; and 4) ant assemblages in different forest types differ in their trophic structure. Base-line corrected mean 8 15N values for different ant species ranged from -0.67 parts per thousand to 10.56 parts per thousand thus confirming that forest ants occupy a variety of trophic levels. Based on stable isotopes we distinguished three major trophic groups: a) species mostly feeding on hemipteran exudates and other plant-derived food resources; b) omnivorous species with mixed diet of plant and animal prey; and c) truly predacious species, including arthropod specialists. Ant subfamilies differed significantly in their trophic positions, as did many ant genera within subfamilies and ant species within ant genera. Several ant species exhibited dietary flexibility and differed significantly in trophic positions across forest types.DFG [PF 441 / 3 - 1, PF 441 / 3 - 3]; DAA
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Chilopoda (Myriapoda) of the Khentey-Mountain Range, Northern Mongolia. Communities of different forest-types under a varying fire regime
No full textThe Khentey-Mountain Range, a "hotspot" of biodiversity in Mongolia, stretches from the Mongolian capital Ulaanbaatar in north-eastern direction towards the Russian border and beyond. A variety of forest types (Light Taiga, Dark Taiga, Mixed Taiga) covers the slopes and intermixes with steppe areas. Wild fires are frequent and a part of ecosystem dynamics. The Chilopoda are one of the most important groups of carnivorous soil arthropods, but little is known about their diversity in Mongolia and response to fires. We sampled chilopods in 94 plots in different forest types with varying fire regime, in three locations in the West, South and East Khentey. Each plot included five pitfall traps and a hand sampling of soil and litter. We recorded ten species of Chilopoda in the Khentey-Mountain region, eight Lithobiomorpha and two Geophilomorpha. Lithobius giganteus Sseliwanoff, 1881 and Lithobius alticus (Loksa, 1965) were by far the most widespread centipede species. Species richness of Chilopoda communities was higher in the West than in the South and East, which was presumably caused by higher precipitation and the resulting higher diversity of the forests. Within the Western Khentey species richness of Chilopoda and tree species increased simultaneously. Generally, we found the highest diversity of Chilopoda at higher altitudes, which corresponds with the increasing precipitation, and -exclusively for the Lithobiomorpha - with locations in floodplain forests. Altogether there was little influence of fire on the diversity and individual density of Chilopoda, although freshly burnt areas provided a short term attraction to certain species. (C) 2016 Elsevier Masson SAS. All rights reserved."German Academic Exchange Service" (DAAD) [D/12/40689, 11000351
Development and application of GIS-based assessment of land-use impacts on water quality: A case study of the Kharaa River Basin
No full textEffective analytical tools, such as geographical information systems (GIS) and multivariate analysis, help to deal with spatial data and complex interactions in watershed management. To investigate the impact of land-use on chemical water quality in the Mongolian Kharaa River Basin, the whole catchment and sub-catchments in relation to each sampling point were delineated. Chemical water quality over three seasons was assessed with GIS and RDA in a modeling approach with forward selection of variables and cluster analysis. The most powerful predictors of river water quality were altitude, settlements, forest, cropland, and distance to spring. In particular, this was true when instead of full sub-basins riparian buffer zones (max. 3 km) were considered. From a management perspective, this implies that the protection of riparian zones should be a priority in the Kharaa basin and similar river basins in Mongolia and Central Asia. Because of its positive effects on water quality, forest protection should be closely coupled with river basin management
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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