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Scientometrics
Authors: Stephen Carley and Alan L. Porter

Abstract

We introduce an indicator to measure the diffusion of scientific research. Consistent with Stirling's 3-factor diversity model, the diffusion score captures not only variety and balance, but also disparity among citing article cohorts. We apply it to benchmark article samples from six 1995 Web of Science subject categories (SCs) to trace trends in knowledge diffusion over time since publication. Findings indicate that, for most SCs, diffusion scores steadily increase with time. Mathematics is an outlier. We employ a typology of citation trends among benchmark SCs and correlate this with diffusion scores. We also find that self-cites do not, in most cases, significantly influence diffusion scores.

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; Porter and Rafols 2009 ; Porter and Youtie 2009 ; Porter et al. 2007 ). Inspired by this approach, here we propose a new version of the diversity index analyzed by the abovementioned authors, which was the Stirling index. As a use case, we

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The main aim of this study was to evaluate the appropriateness of using different diversity indices for conservation purposes in arid environments. The study was done on Mt Serbal as a case study representing mountainous arid areas. Mt Serbal is one of the richest and most diverse areas in Egypt. It was sampled by 97 stands representing different vegetation cover, land-forms and habitats. Species density and environmental factors (including altitude, slope, soil texture, hygroscopic moisture, water holding capacity, pH, EC, and soil organic matter content) were recorded or measured in each stand. The results reveal that Mt Serbal is characterised by a high diversity of plant species and the most diverse area is Shaq Sha’rany. The study recommends Margalef and species richness as the most suitable to measure the diversity at different localities, land-forms, and vegetation groups. It emphasises on the necessity of reporting on species richness in any conservational study. Meanwhile, indices that are excessively sensitive to change in sample size, gear, or handling procedures should be avoided.

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, beyond contrasting the two rankings, we also examine them against a diversity measure (that is, in this context, multidisciplinarity measure) applied in our previous study, the Rao - Stirling diversity . This particular diversity index was chosen for

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Land abandonment is a widespread phenomenon in agricultural systems, especially in former communist countries of Eastern and South-eastern Europe. Moreover, Croatia was affected by acts of war which enhanced the depopulation of marginal areas impelling further land abandonment. Agricultural landscapes in Croatia are highly parcelled with various proportions of forest habitats due to traditional smallholder farming systems. Secondary successions as a consequence of land abandonment affect farmland birds that are among the most endangered bird species in Europe. We examined bird communities along a habitat gradient in heterogeneous agricultural landscapes. We used the share of woody vegetation cover as a proxy measure for land abandonment that we classified in four classes. Our results showed no significant Shannon Wiener Index differences of bird communities along the land abandonment gradient. However, there were differences in abundances when we examined bird guilds such as farmland, forest and “other” birds separately. However, the conservation value of each of the four land abandonment classes did not show significant differences. We extracted single bird species such as the Yellowhammer (Emberiza citrinella), Red-backed Shrike (Lanius collurio), Song Thrush (Turdus philomelos) and European Robin (Erithacus rubecula) as potential indicator species for the four examined land abandonment levels. With these four species we successfully modelled the distribution of the recorded bird assemblages at the plot level along the four vegetation succession stages. We emphasized the need to develop new and integrative land use management concepts for areas affected by land abandonment in order to formulate sound conservation policy.

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Monthly changes in species diversity of aquatic macrophytes (richness and Simpson’s diversity index) were studied in relation to various limnological predictors (including their time lag effects) of two tropical ponds, over a period of three years, using regression analysis with correction for temporal autocorrelation.The monthly mean ± SD number of total plant species was 6±2 and 2±1 in Pond 203 and Pond 206, respectively, with significant pond effect. Immediate and 2-months lag of water temperature in the ‘species rich’ pond (Pond 203) appeared to be the significant predictors for Simpson’s diversity index and total plant species richness, respectively. Secchi depth (1-month lag) was found to be the significant predictor for Simpson’s diversity index in ‘less species rich’ pond (Pond 206), while total plant species richness was not found to be influenced by any limnological predictor. Comparative literature review on maximum number of plant species per pond revealed low richness in tropical and subtropical ponds than their temperate counterparts. Among different growth forms, maximum number of emergent and submerged plant species per pond was also less in tropical climates.

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Abstract

Plant community diversity is a major research focus in community ecology. The relationship between diversity patterns and different diversity indices is important for developing and improving biodiversity protection. In order to fully understand multi-dimensional diversity patterns of the subalpine meadow on Heyeping peak of Luya Mountain, we used a systematic sampling method and set 150 1 m × 1 m plots in June of 2018. Based on an analysis of the subalpine meadow community on Heyeping peak, we measured multiple diversity indices, carried out a correlation analysis between diversity and environmental factors, and compared correlations among different diversity indices. The goal was to clarify the ecological mechanisms and variation among various diversity indices and environmental factors. The main results were as follows: (1) The species diversity distribution was uniform, the taxonomic level was narrow, functional differences were small, and different pedigree structures were present in each plot. (2) A stable correlation between pedigree diversity index (PD) and species diversity index indicated niche conservativism; the net relatedness index (NRI) of community lineage structure was significantly correlated with the nearest species taxon index (NTI), species richness, and evenness index, indicating that plant community composition in the study area is mainly affected by habitat filtration. (3) The average taxonomic distinctness index (Λ+) and the average taxonomic distinctness index (Λ+) had a stable correlation; only the functional richness index (FRic) and Patrick species richness index were closely related. (4) Among the selected environmental factors, only the forest line had a stable correlation with species diversity index and PD and showed a negative correlation change, indicating an “edge effect” distribution of species diversity in the study area. In summary, the forest line was the key factor affecting the distribution of species diversity in the study area and the species relationships within the community. This work was supported by the National Natural Science Foundation of China (31400358).

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The species composition and diversity of epipelic algae and physicochemical characteristics in Limni Lake were studied between June and November 2005. The epipelic algal flora is comprised of 46 taxa from four divisions: Bacillariophyta (22), Chlorophyta (15), Euglenophyta (8) and Dinophyta (1). Gonatozygon aculeatum is a new record for Turkey. Some physical factors, such as light and temperature affected development of the epipelic algal flora. The seasonal changes in the diversity index showed an inverse pattern to total cell number. Limni Lake has eutrophic lake characteristics.

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The diversity of fungal endophytes is poorly known and particularly in the case of Nicotiana tabacum, the literature is limited. The present study assessed and compared the diversity and distribution of endophytic fungi between different organs of tobacco plants. We calculated the relative frequency and rates of colonisation and of isolation of endophytic fungi in roots, stems and leaves, as well as the Shannon–Wiener and Simpson diversity indexes. Similarities between assemblages from the studied organs were also analysed. A total of 1588 endophytic fungal strains assigned to 31 morphospecies were isolated. The highest diversity of endophytes was found in leaves, being Fusarium graminearum and Alternaria botrytis the most common fungal species. This study provides information on the distribution of fungal endophytes inhabiting leaves, stems, and roots of N. tabacum and thus can serve as a starting point for increasing our comprehension on the interactions in which these fungi are involved.

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The variability of microsatellite markers of 16 genotypes of triticale (× Triticosecale Wittmack, 2n = 6x = 42, BBAARR) was studied. Five varieties from Poland (Gutek, Kitaro, Lamberto, Presto and Tornado), three from Germany (Lupus, Ticino and Triamant), one from Russia (Valentin-90) and seven translocation forms derived from cv. Presto (donors of good bread-making quality) were analysed. SSR markers localised on chromosomes of the A, B, D and R genomes were chosen from literature for analysis. Based on 48 SSR markers (27 wheat and 21 rye SSR markers) a dendrogram was calculated, which highly significantly differentiated the Valentine-90 genotype from all the other 15 genotypes split into three sub-clusters. The first one includes the cv. Gutek, Tornado, Presto and translocation forms of cv. Presto. The second sub-cluster consists of the cv. Kitaro, Lamberto, Ticino and Triamant. The third sub-cluster cluster consists of the cv. Lupus only. The diversity index (DI), the probabilities of identity (PI) and the polymorphic information content (PIC) of SSR markers were calculated. We detected 184 alleles from 48 markers with an average of 3.83 alleles per locus (ranging from 1 to 9 alleles per locus). The average polymorphic information content was 0.48 ranging between 0.00 and 0.85.

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