1,721,329 research outputs found
Co-limitation toward lower latitudes shapes global forest diversity gradients
No full textThe latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers.EEA Santa CruzFil: liang, Jingjing. Purdue University. Department of Forestry and Natural resources. Forest Advanced computing and Artificial Intelligence Laboratory (FAcAI); Estados UnidosFil: Gamarra, Javier G. P. Food and Agriculture Organization of the United Nations. Forestry Division; Italia.Fil: Picard, Nicolas. GIP ECOFOr; FranciaFil: Zhou, Mo. Purdue University. Department of Forestry and Natural resources. Forest Advanced computing and Artificial Intelligence Laboratory (FAcAI); Estados UnidosFil: Pijanowski, Bryan. Purdue University. Department of Forestry and Natural resources; Estados UnidosFil: Jacobs, Douglass F. Purdue University. Department of Forestry and Natural resources; Estados UnidosFil: Reich, Peter B. University of Michigan. Institute for Global change biology. School for environment and Sustainability; Estados UnidosFil: Reich, Peter B. University of Minnesota. Department of Forest resources; Estados UnidosFil: Reich, Peter B. Western Sydney University. Hawkesbury Institute for the environment; Australia.Fil: Crowther, Thomas W. Institute of Integrative biology. Crowther Lab. Department of environmental Systems Science; SuizaFil: Nabuurs , Gert-Jan. Wageningen University and research. Wageningen environmental research; Países BajosFil: Nabuurs , Gert-Jan. Wageningen University and research. Forest ecology and Forest Management Group; Países BajosFil: de-Miguel, Sergio. University of Lleida. Department of crop and Forest Sciences; EspañaFil: de-Miguel, Sergio. Joint research Unit CTFC. Agrotecnio cercA; EspañaFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Hui, Cang. Stellenbosch University. Department of Mathematical Sciences. Centre for Invasion biology; SudáfricaFil: Hui, Cang. African Institute for Mathematical Sciences; Sudáfric
Does the law of diminishing returns in leaf scaling apply to vines? – Evidence from 12 species of climbing plants
No full text
DISCARD_IPBES Invasive Alien Species Assessment: Chapter 2. Figures, tables, captions and data management reports
No full text<p>Figures, tables, captions and data management reports from Chapter 2: Trends and status of alien and invasive alien species. In: Thematic Assessment Report on Invasive Alien Species and their Control of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.</p>
Around the world in 500 years: Inter‐regional spread of alien species over recent centuries
Full text linkAim: The number of alien species has been increasing for centuries world-wide, but temporal changes in the dynamics of their inter-regional spread remain unclear. Here, we analyse changes in the rate and extent of inter-regional spread of alien species over time and how these dynamics vary among major taxonomic groups. /
Location: Global. /
Time period: 1500–2010. /
Major taxa studied: Vascular plants, mammals, birds, fishes, arthropods and other invertebrates. /
Methods: Our analysis is based on the Alien Species First Record Database, which comprises >60,000 entries describing the year when an alien species was first recorded in a region (mostly countries and large islands) where it later established as an alien species. Based on the number and distribution of first records, we calculated metrics of spread between regions, which we termed “inter-regional spread”, and conducted statistical analyses to assess variations over time and across taxonomic groups. /
Results: Almost all (>90%) species introduced before 1700 are found in more than one region today. Inter-regional spread often took centuries and is ongoing for many species. The intensity of inter-regional spread increased over time, with particularly steep increases after 1800. Rates of spread peaked for plants in the late 19th century, for birds and invertebrates in the late 20th century, and remained largely constant for mammals and fishes. Inter-regional spread for individual species showed hump-shaped temporal patterns, with the highest rates of spread at intermediate alien range sizes. Approximately 50% of widespread species showed signs of declines in spread rates. /
Main conclusions: Our results show that, although rates of spread have declined for many widespread species, for entire taxonomic groups they have tended to increase continuously over time. The large numbers of alien species that are currently observed in only a single region are anticipated to be found in many other regions in the future
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
Leaf Bilateral Symmetry and the Scaling of the Perimeter vs. the Surface Area in 15 Vine Species
No full textThe leaves of vines exhibit a high degree of variability in shape, from simple oval to highly dissected palmatifid leaves. However, little is known about the extent of leaf bilateral symmetry in vines, how leaf perimeter scales with leaf surface area, and how this relationship depends on leaf shape. We studied 15 species of vines and calculated (i) the areal ratio (AR) of both sides of the lamina per leaf, (ii) the standardized symmetry index (SI) to estimate the deviation from leaf bilateral symmetry, and (iii) the dissection index (DI) to measure leaf-shape complexity. In addition, we examined whether there is a scaling relationship between leaf perimeter and area for each species. A total of 14 out of 15 species had no significant differences in average ln(AR), and mean ln(AR) approximated zero, indicating that the areas of the two lamina sides tended to be equal. Nevertheless, SI values among the 15 species had significant differences. A statistically strong scaling relationship between leaf perimeter and area was observed for each species, and the scaling exponents of 12 out of 15 species fell in the range of 0.49−0.55. These data show that vines tend to generate a similar number of left- and right-skewed leaves, which might contribute to optimizing light interception. Weaker scaling relationships between leaf perimeter and area were associated with a greater DI and a greater variation in DI. Thus, DI provides a useful measure of the degree of the complexity of leaf outline
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
IPBES Invasive Alien Species Assessment: Chapter 2. Figure and data management report
No full text<p>This folder contains the figures included in chapter 2 of the IPBES thematic assessment of invasive alien species and their control. If possible, each figure is provided in png and pdf format. In addition, the R scripts and the data sets required to generate the figures and most tables are provided as well.</p>
<p>The figures and tables showing information about alien species numbers or distributions are all based on two data sets, which are stored on Zenodo folders. One data set contains the records of alien species per region worldwide (https://doi.org/10.5281/zenodo.7554428) and the workflow including R scripts have been published (https://doi.org/10.3897/neobiota.59.53578). This data set is called the 'chapter database'. Version 2.4.1 of this data set was used to extract the numbers shown in figures and tables of this chapter. The second data set (https://doi.org/10.5281/zenodo.6458083) contains coordinates of alien species occurrences worldwide and the workflow including R scripts have also been published elsewhere (https://doi.org/10.3897/neobiota.74.81082). Version 1.0.1 of this data set was used here.</p>
<p>The folder also contains the data management reports for the generation of the chapter database and figures.</p>Data management reports adde
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