1,721,313 research outputs found
Data and ancillary data for publication: Natural infrastructure and water erosion mitigation in the Andes
No full textThe data contain information on the effectiveness of natural infrastructure to mitigate soil erosion. Data were compiled from 118 case studies from the Andean region, whereby information on natural infrastructure interventions, soil erosion and soil quality were tabulated and analysed.
The data contains the following documents:
-Database with data on soil erosion, soil quality for different types of natural infrastructure (118 case studies)
-Metadata
-Summary of terms used in the systematic review of the literature (in Spanish and English)
-List of bibliographic data sources that were searched with the search terms
-Full bibliographic references of all 118 case studies
Full reference
Vanacker V, Molina A, Rosas-Barturen M, Bonnesoeur V, Román-Dañobeytia F, Ochoa-Tocachi B, Buytaert W (2022). The effect of natural infrastructure on water erosion mitigation in the Andes
Erosion regulation as a function of human disturbances to vegetation cover: A conceptual model
No full textHuman-induced land cover changes are causing important effects on the ecological services rendered by mountain ecosystems, and the number of case-studies of the impact of humans on soil erosion and sediment yield has mounted rapidly. In this paper, we present a conceptual model that allows evaluating overall changes in erosion regulation after human disturbances. The basic idea behind this model is that soil erosion mechanisms are independent of human impact, but that the frequency-magnitude distributions of erosion rates change as a response to human disturbances. Pre-disturbance (or natural) erosion rates are derived from in situ produced 10Be concentrations in river sediment, while post-disturbance (or modern) erosion rates are derived from sedimentation rates in small catchments. In its simplicity, the model uses vegetation cover change as a proxy of human disturbance. The erosion regulation model is here applied in two mountainous regions with different vegetation dynamics, climatic and geological settings: the Austro Ecuatoriano, and the Spanish Betic Cordillera. Natural erosion benchmarks are necessary to assess human-induced changes in erosion rates. While the Spanish Betic Cordillera is commonly characterized as a degraded landscape, there is no significant difference between modern catchment-wide erosion and long-term denudation rates. The opposite is true for the Austro Ecuatoriano where the share of natural erosion in the total modern erosion rate is minimal for most disturbed sites. When pooling pre- and post-disturbance erosion data from both regions, the data suggest that the human acceleration of erosion is related to vegetation disturbances. The empirical regression model predicts human acceleration of erosion, here defined as the ratio of post-disturbance to pre-disturbance (or natural benchmark) erosion rate, as an exponential function of vegetation disturbance. This suggests that the sensitivity to human-accelerated erosion would be ecosystem dependent, and related to the potential vegetation cover disturbances as a result of human impact. It may therefore be expected that the potential for erosion regulation is larger in well-vegetated ecosystem where strong differences may exist in vegetation cover between human disturbed and undisturbed or restored sites. © 2013 Springer Science+Business Media Dordrecht
Vegetation control on nutrient availability and supply in high-elevation tropical Andean ecosystems
No full textPlants absorb nutrients and water through their roots, and modulate soil biogeochemical cycles. The mechanisms of water and nutrient uptake by plants depend on climatic and edaphic conditions, as well as the plant root system. Soil solution is the medium in which abiotic and biotic processes exchange nutrients, and nutrient concentrations vary with the abundance of reactive minerals and fluid residence times. High-altitude ecosystems of the tropical Andes are particularly interesting to study the association between vegetation patterns, soil hydrology and soil nutrient availability. The páramo landscape forms a vegetation mosaic of bunch-grasses, cushion-forming plants and forests. In the nutrient-depleted nonallophanic Andosols, the plant rooting depth varies with drainage and soil moisture conditions. Vegetation composition is a relevant indicator of rock-derived nutrient availability in soil solutions. The soil solute chemistry revealed patterns in plant available nutrients that were not mimicking the distribution of total rock-derived nutrients nor the exchangeable nutrient pool, but clearly resulted from strong biocycling of cations and removal of nutrients from the soil by plant uptake or deep leaching. Our findings have important implications for future management of Andean páramo ecosystems where vegetation type distributions are dynamically changing as a result of warming temperatures and anthropogenic disturbances. Such alterations may not only lead to changes in soil hydrology and solute geochemistry but also to complex changes in weathering rates and solute export downstream with effects on nutrient availability in Andean rivers and high-mountain lakes
Patterns in soil chemical weathering related to topographic gradients and vegetation structure in a high Andean tropical ecosystem
No full textAlthough climate exerts a major control on mineral weathering and soil formation processes, the combined effect of vegetation and topography can influence the rate and extent of chemical weathering at the hillslope scale. In this paper, we examined spatial patterns in volumetric strain and soil weathering extent associated with topographic gradients and vegetation patterns. In a high Andean catchment, we selected 10 soil toposequences on andesitic flows: 5 under tussock grasses, 3 under cushion forming plants and 2 under native forest. Along each toposequence, one pit was excavated at the shoulder, backslope and toeslope resulting in 30 soil profiles. Depth‐weighted total soil porosity of the thirty soil profiles averaged 64±6%. The association between volumetric strain and soil organic C indicates that biotic agents can be effective in dilating the regolith during weathering. The young, postglacial volcanic soils were depleted in mono‐ and divalent cations, with total mass losses ranging between 793 and 1610 kg.m‐2. The accumulation of Al‐humus complexes in the soil matrix plays an essential role in chemical transformation of the non‐allophanic soils. Beyond the marginally significant topographic control on chemical weathering extent, our data show highly significant differences in chemical weathering extent between vegetation communities with total mass losses in forest soils being respectively 19% and 22% higher than in grasslands and cushion forming plants. The vegetation mosaic in alpine ecosystems might therefore provide essential clues to understand soil chemical weathering patterns caused by spatially varying soil particle and water residence times
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
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