1,721,011 research outputs found
Are spiders reacting to local or landscape scale effects in Hungarian pastures?
No full textDeclines of West-European farmland biodiversity have been associated with intensive agricultural practices, Central and Eastern European grasslands still harbour a diverse and unique arthropod community. However, our understanding of the effects of farmland management both at local and landscape levels is rather limited there. A paired field approach was used to compare extensively (0.5 cows/ha) and intensively (> 1 cows/ha) grazed pastures in 42 fields in three distinct biogeographic regions within Hungary. Spiders belonging to the hunting and web-building communities were sampled using funnel traps. We found no management effect either on richness and abundance or on species composition, which shows that both forms of grazing management at the intensity levels studied support valuable spider fauna. At the local scale plant and litter cover were the two most important variables that significantly affected the communities overall, meaning both the hunting and to some degree the web-building communities. No significant landscape effects were found in the analyses on spider richness and abundance, but community structure was affected by two landscape level factors (grassland patch density and grassland percentage). We suggest that to protect the valuable spider and other fauna of these regions, the recently launched national agri-environmental program should be further supported and enlarged to maintain and reintroduce the traditional grazing management on these semi-natural grasslands. (C) 2008 Elsevier Ltd. All rights reserved
A budai Sas-hegy pókegyütteseinek hosszú- és rövidtávú változása, különös tekintettel a gyeprehabilitációs kezelések hatására
Full text linkA Budai Sas-hegy a főváros által körbezárt különleges természeti kincsünk. Pókfaunája jól kutatott: 1930-34 között Balogh János, 1994-98 között Szinetár Csaba és Samu Ferenc végeztek részletes gyűjtéseket. Jelen munkánkban a 90-es években felmért 5 konkrét gyepfoltban az akkori protokollt pontosan megismételve vettünk mintákat 2010-ben, egy éven át. Célunk a hegyen zajló hosszú távú változásokat feltárása volt a két megelőző vizsgálattal való összehasonlítással, továbbá a rövid távú változások kimutatása az egyes gyepfoltok pókegyütteseinek 90-es évek óta történt változásainak kvantitatív vizsgálatával. A hegyen egyre terjedő orgona visszaszorítására 2008-tól természetvédelmi célú cserjeirtásokat végeznek, amely 3 vizsgált gyepfoltunkat is részben érintett. Ezeknél az irtott és kezeletlen részben is vettünk mintát. A vizsgálat során 105 pókfajt azonosítottunk, ebből 16 a hegy faunájára nézve új. 80 év távlatában a gyakori státuszú fajok populációi inkább növekedtek, a ritkáké pedig inkább csökkentek, de a fajok természetességi vagy egyéb ökológiai karaktereinek átlagában nem történt elmozdulás. A hegyet fémjelző ritka fajokat sikerült kimutatnunk. A fajkompozíció a 90-es évekhez képest is jelentős sodródást mutatott. Az időbeli eltávolodáshoz mérten az irtott és kezeletlen foltok között kis különbség volt, valószínűleg a gyors visszatelepülés, és a nem totális kezelés miatt. A fajok átlagos ritkasági értékét tekintve az irtott foltok hasonlóbbak voltak a 90-es évekbeli állapotukhoz, mint a kezeletlen párjukhoz. Úgy véljük, a hegy megőrizte ritka fajokban gazdag pókfaunáját, valamint a cserjeirtás hatására, az eredetihez hasonlóbb élőhelyek jöttek létre, ami kedvezhet több ritka faj populációjának
Local and landscape management drive trait-mediated biodiversity of nine taxa on small grassland fragments
No full textAimBiodiversity across the globe is heavily eroded by intensified management at local and landscape scales. Species communities of calcareous grasslands, which are among Europe's most diverse habitats, are severely threatened by the cessation of appropriate traditional management, loss of habitat connectivity and simplification of the surrounding landscape. However, our understanding of these often interrelated factors remains limited, in particular for trait-mediated responses across taxa. Here, we test the independent effects of local management (grazing, mowing and abandonment), habitat connectivity (measured by a connectivity index) and landscape complexity (indicated by the percentage of arable land) on nine taxa: plants, butterflies, bees, grasshoppers, hoverflies, spiders, true bugs, rove beetles and leafhoppers on small semi-natural calcareous grassland remnants (<1ha). LocationCentral Germany. MethodsWe use a joint analysis across taxa to identify general and trait-mediated responses (body size and Red List status) in species richness, abundance and community composition. ResultsWe identified three key drivers of local diversity patterns: First, an increasing proportion of arable land from 10% to 80% led to a 29% loss of overall species richness. Second, despite differences between taxa, increasing habitat connectivity generally enhanced species richness. Connectivity effects were more accentuated in the large species per taxon, which can be expected to be good dispersers. Finally, grazing reduced species richness and abundance much more than annual mowing or short-term abandonment (5-15years), in particular for red-listed species. We attribute this to plant resource removal through overgrazing and trampling. Main conclusionsFor the conservation management of small calcareous grasslands, we advocate an alternating strategy of mowing or lenient grazing and short-term abandonment, prioritizing connected fragments surrounded by diverse landscapes. Despite taxon-specific responses, our study across nine taxa demonstrates universal, trait-mediated effects of management, landscape complexity and connectivity on local biodiversity in fragmented communities
Spillover of arthropods from cropland to protected calcareous grassland – the neighbouring habitat matters
No full textSpillover effects of organisms from semi-natural habitats to adjacent crops have been frequently reported, yet evidence for the reversed process and associated functional consequences remains scarce. We examined the spillover of carabids, rove beetles and spiders from agricultural lands to protected, high-nature value calcareous grasslands by comparing two neighbourhood types: seven calcareous grasslands neighbouring intensively managed winter wheat fields and seven calcareous grasslands neighbouring intensively managed meadows in Germany. We examined arthropod activity density with repeated pitfall trapping in both the edge and the interior of all three habitat types (14 study sites). All three arthropod groups showed consistently higher activity density in calcareous grasslands adjacent to wheat fields than calcareous grasslands adjacent to meadows, apparently through spillover effects. Activity density of carabids and spiders exhibited a decline from the interior to the edge of the wheat fields and to even lower density at the edge and lowest density in the interior of the calcareous grassland. Carabid spillover from both neighbouring habitats to grasslands was driven by a dominant predatory species, Pterostichus melanarius, whereas Oedothorax apicatus was the dominant contributor to spider spillover from wheat to grasslands. Our results show that neighbourhood identity (wheat or meadow) can shape arthropod density and community composition in semi-natural habitats due to spillover of carabid beetles, spiders and rove beetles from adjacent crop fields. Neighbourhood effects on spillover are thus more accentuated at the cropland-grassland interface compared to the meadow-grassland boundary, with small grasslands being particularly affected due to their high edge-to-interior ratios. Our results suggest that meadows around high-nature value, protected grassland reserves, may be important conservation elements by attenuating arthropod spillover from arable crops. Such spillover may compromise the identity, structure and functioning of endangered communities
Responses of plant, insect and spider biodiversity to local and landscape scale management intensity in cereal crops and grasslands
No full textThe aim of this study was to determine the relative effects of landscape scale management intensity, agroecosystem type, local management intensity and edges on diversity patterns of functional groups of plants, carabid beetles, spiders and grasshoppers. Nine landscapes were selected differing in percent intensively used agricultural area (IAA), each with a pair of organic and conventional winter wheat fields and a pair of organic and conventional mown meadows. Within fields, plants were surveyed in the edge and in the interior. Carabid beetles and spiders were captured by funnel traps, while grasshoppers were sweep-netted in the meadows. Diversity patterns of study organisms were affected both by local variables (local management, agroecosystem type and within-field position) and by landscape scale management intensity. Species richness of grasses, presumably because of sowing low-diversity mixtures, and hunting spiders decreased with percent cover of IAA. Meadows differed from wheat fields in that they had higher species richness of forbs and grasses, as well as higher densities of hunting spiders. In contrast, more carabid individuals, especially of non-carnivore species, were captured in wheat fields. In field edges with their reduced management intensity and increased immigration, species richness of plants, carabids and spiders was higher than in the interiors regardless of agroecosystem type and management. Organic management enhanced forb richness and cover in both agroecosystem types. Organic management also increased grass cover in wheat fields, but not in meadows, and promoted species richness of non-carnivore carabids and hunting spiders, but not grasshoppers. The results show that agri-environmental management needs to be targeted to the agroecosystem's field size, because higher edge area led to higher species richness. Organic management affected several functional groups positively (forbs, non-carnivore carabids, hunting spiders), while lower landscape scale management intensity only increased species richness of grasses and spiders. The great differences in responses of functional groups to local cereal and grassland as well as landscape management suggest implementing more scale and group specific targets for agri-environmental schemes to improve their efficiency
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
The effect of exposition time and temperature on spiders (Araneae) overwintering on the bark of black pine (Pinus nigra)
No full textThe effect of exposition time (time between the installation of traps and the collection of spiders) and
autumn air temperature on spiders overwintering on tree bark was studied in a planted black pine forest
(Pinus nigra) near Debrecen (east Hungary). We collected spiders from traps fixed 2 m high on tree
trunks once every five days for 50 days in 1999 and 2000. We collected 957 spiders belonging to 15
species and 1 species determined to the genus level in the two years combined. In 1999, the diversity
and number of spiders increased with exposition time but were not influenced by temperature when
data were combined for each sampling time. This was because temperature was low in the middle of
the sampling period, but increased again at the end, which weakened its effect. However, the diversity
and number of individuals continued to increase even when temperature increased at the end of the
sampling period. In 2000, the number of individuals increased by exposition time because we found individuals
of Philodromus margaritatus in very high numbers on the last sampling occasion. There were no
other differences in 2000 because temperature was constantly high during the sampling period. Our
results suggest that the movement of spiders to the bark is a characteristic process and that the diversity
and number of spiders continue to increase in the autumn even when temperature slightly increases.
This process, however, can be delayed if temperature is constantly high during the study period
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
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