1,720,962 research outputs found
HABITAT REQUIREMENTS OF THE PROTECTED SOUTHERN FESTOON (ZERYNTHIA POLYXENA); ADULT, EGG AND LARVAL DISTRIBUTION IN A HIGHLY DEGRADED HABITAT COMPLEX
No full textHabitat quality affects the presence and size of butterfly populations. Resources for all life stages must be found in a given or few habitat patches. Southern festoon (Zerynthia polyxena) is a vulnerable, but locally abundant species in Hungary. The larva requires birthwort (Aristolochia clematitis) as food plant. We examined the small scale habitat use of adults and distribution of eggs and larvae among different vegetation types to reveal the requirements of the species in all life stages. Transect counts were conducted in a tree plantation complex comprising four types of vegetation. Number (+/- SE) of adults, eggs and larvae were lowest in poplar plantation (adult 0.3 +/- 0.2, egg 1.1 +/- 1.1, larva 0.6 +/- 0.3). Medium amount of butterflies were observed in open (adult 8.3 +/- 2.9, egg 3.1 +/- 2.6, larva 3.1 +/- 1.9) and black-locust (adult 9.4 +/- 4.2, egg 12.7 +/- 4.9, larva 4.1 +/- 1.1) habitat. Number of butterflies was highest in hummocks (adult 13.5 +/- 1.5, egg 12.9 +/- 5.7, larva 8.4 +/- 2.1). Adults avoided bare ground. We encountered most eggs in dense food plant patches with high plants. Food plant height also positively influenced the occurrence of the larvae. Although distribution of adults and juvenile forms showed quite similar patterns, we could also reveal some differences that caused by different environmental conditions in distinct vegetation types. Our study stresses the importance of habitat quality, which affects population size of butterflies even in a highly degraded habitat complex
Effects of grazing, vegetation structure and landscape complexity on grassland leafhoppers (Hemiptera: Auchenorrhyncha) and true bugs (Hemiptera: Heteroptera) in Hungary
No full text1. Agricultural intensification is a major cause of biodiversity loss in European farmlands. Grasslands are particularly important habitats for the conservation of rich insect assemblages of Central and Eastern Europe. Although regular grazing or mowing of these grasslands is required to maintain diversity, there is no information about how such management and other factors influence Hemiptera assemblages. 2. We studied leafhopper and true bug assemblages in semi-natural grasslands in three regions of the Great Hungarian Plain. We investigated how local vegetation factors and landscape complexity influence assemblages and whether they interact with management effects. 3. Seven pairs of intensively (>1 cow/ha) versus extensively (similar to 0.5 cow/ha) grazed pastures were sampled in each region by sweep-netting. 4. Sward height was the most important explanatory factor for leafhoppers (84 species, 27264 individuals), as it increased both species number and abundance, and influenced assemblage composition. The extent of grassland surrounding the sample sites negatively affected leafhoppers, whereas extensive grazing decreased abundance and influenced composition. True bug assemblages (140 species, 6656 individuals) were positively affected only by mean sward height, whereas regional differences determined the community composition of both taxa. 5. We conclude that vegetation structure is the primary factor shaping Hemiptera communities and that the various types of grasslands studied are all important habitats for the taxon. Therefore, cattle grazing in its current form is beneficial for the rich Hemiptera fauna in lowland pastures of Hungary. However, in some cases, local and landscape factors and great regional differences may confound the effects of grazing, and this must be considered in conservation planning in the future
Different habitat selection by two sympatric Maculinea butterflies at small spatial scale
No full text. 1. Worldwide extinction of species due to habitat loss and habitat degradation can be recognised among butterflies pronouncedly. Therefore, conservation biologists devote special attention to identify the most important ecological factors affecting distribution and survival of butterflies. These efforts have been dominated by landscape-scale studies, although variation in habitat quality at smaller spatial scales may be of crucial importance. This applies for the highly specialised Maculinea species, which usually do not form classic metapopulations. 2. Maculinea nausithous and Maculinea teleius use the same larval food plant and usually occupy the same habitats in Europe. Afforestation of meadows due to abandonment is a major threat for these species. However, few if any studies have assessed the effects that proximity of forest edges may have on the habitat selection by adult butterflies at the scale of local populations. Here, we aimed to test these effects within one habitat fragment based on an intensive mark-release-recapture sampling. 3. Distribution of M. nausithous was aggregated and its density was highly positively influenced by the proportion of afforested meadow edges, while M. teleius showed no preference for afforested edges. Despite their different within-habitat distribution, the movement of both species was restricted to smaller parts of the habitat. 4. Our results suggest that M. nausithous has a narrower niche in the study region, which is most likely due to that its only host ant can find suitable microclimatic conditions at the afforested edges of wet meadows. This implies that habitat patches are not equally used by the two species and hence different management approaches are desirable for their conservation.EC [EVK2-CT-2001-00126]; NKTH [NKFP 3B023-04
Potential metapopulation structure and the effects of habitat quality on population size of the endangered False Ringlet butterfly
No full textThe False Ringlet (Coenonympha oedippus) is a European butterfly species, endangered due to the severe loss and fragmentation of its habitat. In Hungary, two remaining populations of the butterfly occur in lowland Purple Moorgrass meadows. We studied a metapopulation occupying twelve habitat patches in Central Hungary. Our aim was to reveal what measures of habitat quality affect population size and density of this metapopulation, estimate dispersal parameters and describe phenology of subpopulations. Local population sizes and dispersal parameters were estimated from an extensive mark-release-recapture dataset, while habitat quality was characterized by groundwater level, cover of grass tussocks, bush cover, height of vegetation and grass litter at each habitat patch. The estimated size of the metapopulation was more than 3,000 individuals. We estimated a low dispersal capacity, especially for females, indicating a very low probability of (re)colonization. Butterfly abundance and density in local populations increased with higher grass litter, lower groundwater level and larger area covered by tussocks. We suppose that these environmental factors affect butterfly abundance by determining the microclimatic conditions for both larvae and adult butterflies. Our results suggest that the long-term preservation of the studied metapopulation needs the maintenance of high quality habitat patches by appropriate mowing regime and water regulation. Management also should facilitate dispersal to strengthen metapopulation structure with creating stepping-stones or gradually increase habitat quality in present matrix
Effects of timing and frequency of mowing on the threatened scarce large blue butterfly - A fine-scale experiment
No full textAs part of a major transformation of the EU agriculture in the last few decades, traditional land-use types disappeared due to either intensification or abandonment. Grasslands are highly affected in this process and are consequently among the most threatened semi-natural habitats in Europe. However, experimental evidence is scarce on the effects of management types on biodiversity. Moreover, management types need to be feasible within the recently changed socio-economic circumstances in Hungary. We investigated the effects of timing and frequency of mowing on the abundance of the scarce large blue butterfly (Phengaris teleius), on the abundance of its host plant and on the frequency of its host ant species. In each of four study meadows, we applied four types of management: one cut per year in May, one cut per year in September, two cuts per year (May and September) and cessation of management. After three years of experimental management, we found that adult butterflies preferred plots cut once in September over plots cut twice per year and abandoned ones, while plots cut once in May were also preferred over abandoned plots. Relative host plant abundance remarkably increased in plots cut once in September. Management did not affect the occupancy pattern of Myrmica host ants. Invasive goldenrod was successfully retained by two cuts per year. To our knowledge, this is the first attempt to test management effects on the whole community module of a socially parasitic butterfly, its host plant and host ants. Based on the results, we provide recommendations on regional management of the scarce large blue's habitats. (C) 2014 Elsevier B.V. All rights reserved.German Research Foundation [DFG BA 4438/1-1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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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