1,720,986 research outputs found
High C stocks in Umbrisols in Valgrande National Park (NW Italy)
Full text linkValgrande National Park is characterized by a particularly high mean precipitation amount (up to 2500-3000 mm per year), and this factor contributes to the widespread presence of Umbrisols. In order to understand their distribution and pedogenesis, we opened and analyzed 19 soil profiles and observed many non-analyzed minipits under different land uses.
The results show that Umbrisols are indeed the most common soil types under most land uses. Cambisols can be observed only in highly disturbed positions, while Umbric Podzols can be found under heath. Commonly, Umbrisols also have a black Sombric Bh horizon below 30 cm of depth.
As expected on sialic parent materials under a very wet climate, the soils are extremely acidic and dominated by exchangeable Al.
The C stocks are high, with values commonly above 18-20 kg/m2, mainly located in the mineral horizons. There are no differences with land uses: the lowest C stocks were measured in disturbed soil profiles, where erosion or recent deposition made the soil less thick. 1-3 C kg/m2 are stored in organic layers, with the highest values measured in Umbric Podzols under heath. 40-60% of the total C stored in mineral horizons is located under 30 cm of depth, thus measuring its content only in the top 30 cm would lead to a huge underestimation of C stocks
Genesi dei suoli nelle aree proglaciali del Monte Bianco: Miage e Pré de Bar = Soil genesis in the proglacial areas in Mont Blanc: Miage and Pré de Bar examples
No full textGli ambienti proglaciali dei ghiacciai di Miage e Pré de Bar, lasciati liberi durante l’arretramento dei ghiacci in periodi più o meno recenti, rappresentano due esempi estremamente diversi di sviluppo degli ecosistemi associato al cambio climatico. Le morene del ghiacciaio del Miage, in particolare, rappresentano uno dei rari esempi sulle Alpi di sviluppo dei suoli e della vegetazione su un’ampiezza temporale millenaria, a partire da 4000 anni fa circa. In particolare, la presenza di rocce metamorfiche in aggiunta al granito tipico del massiccio del Monte Bianco, rende il materiale più alterabile e i suoli si sviluppano in tempi molto rapidi, raggiungendo lo stadio maturo in poco più di 2000 anni (sulle Alpi, il tempo medio è di circa 5000 anni). La situazione è estremamente diversa nell’area proglaciale del Pré de Bar, dove il paesaggio rimane pressoche spoglio di vegetazione e i suoli estremamente poco evoluti per più di 190 anni.The proglacial environments of the Miage and Pré de Bar glaciers, deposited during ice retreat in more or less recent periods, represent two extremely different examples of ecosystem development associated with climate change. The moraines of the Miage glacier, in particular, represent one of the rare examples in the Alps of development of soils and vegetation over a millennial time span, starting about 4,000 years ago. In particular, the presence of metamorphic rocks in addition to the granite typical of the Mont Blanc massif makes the material more alterable, and soils develop very rapidly, reaching the mature stage in just over 2,000 years (in the Alps, the average time is about 5,000 years). The situation is extremely different in the Pré de Bar proglacial area, where the landscape remains almost free of vegetation and the soils extremely undeveloped for more than 190 years
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
Intense pedogenic development and large carbon contents in soils above the Pleistocene trimline (NW Italian Alps)
Full text linkMost of the Alpine range was influenced by glacier movement or by intense erosive processes during Pleistocene glacial periods, which erased previously existing soils and landforms. Thus, most of the soils in the Alps began developing since at least the end of the Last Glacial Maximum (LGM). However, some surfaces located above the trimline (the upper limit reached by valley and cirque glaciers) still retain “old” morphologies and can be considered paleosurfaces, often covered by fossil or active periglacial features.
After having found very well developed Umbrisols hidden inside blockfields at 3030 m a.s.l. on the Stolenberg Plateau, Monte Rosa Massif – NW Italian Alps (Pintaldi et al. 2021a, 2021b, 2022), we explored other relict cryogenic landforms located above the Pleistocene trimline, such as blockfields and blockstreams, observing the soils hidden below the surface stone layers.
In most cases, we found extremely well-developed soils, such as Podzols with extremely thick E horizons or Umbrisols with A-Bh horizons up to more than 1-m thick. One of the most important properties was the large organic carbon content, up to 10-13% in soils located inside barren blockstreams and blockfields presently devoid of vegetation, at elevations between 1000 and 2950 m a.s.l..
The age of this organic matter is likely very old. For instance, inside the blockfield on the
Stolenberg Plateau (3030 m a.s.l.), the organic matter was up to 22 ka old, corresponding to the early retreat glacial phase after the LGM. The age and nature of the organic matter in the other soils is still being analyzed, and it will be able to give important information on past environmental condition in understudied high-elevation areas in the Alps
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
Unravelling the existence of Alpine Nunataks: the hidden paleosols of the Stolenberg Plateau (NW Italy)
Full text linkNegli ambienti montani d’alta quota, le glaciazioni Pleistoceniche e i fenomeni erosivi hanno cancellato i suoli pre-esistenti. Tuttavia, su alcune superfici relitte, suoli antichi possono essersi preservati, grazie alla copertura di ghiacciai non erosivi a base fredda o al di sopra dei Nunataks. Lo studio è stato svolto nell’ambiente periglaciale del Plateau dello Stolenberg, a 3030 m, ai piedi del versante sud del Monte Rosa (Alpi Occidentali). Il Plateau è ricoperto da una spessa coltre di forme periglaciali e da una scarsa copertura vegetale (3-5% della superficie). All’interno delle forme periglaciali sono stati rinvenuti degli Umbrisols ben sviluppati, caratterizzati da orizzonti A spessi (30-65 cm) e scuri. Gli stocks di carbonio di questi suoli sono paragonabili a quelli di suoli vegetati o di suoli forestali. Indagini geofisiche hanno dimostrato che i suoli sono ampiamente diffusi sotto la coltre pietrosa, con spessori variabili tra i 20 e i 90 cm. Le datazioni al radiocarbonio, comprese tra i 4.4 e i 22 ka BP, hanno rivelato che tali suoli sono dei paleosuoli, sviluppatisi durante le fasi climatiche calde a partire dalla fine dell’Ultimo Massimo Glaciale (LGM). La caratterizzazione chimico-fisica della sostanza organica ha rivelato che la maggior parte del carbonio organico risiede nella frazione organica associata alla fase minerale. Tale frazione risulta essere costituita da cere, lipidi, cellulose ed emicellulose, derivanti da antiche specie alpine autoctone. Sulla base dei risultati ottenuti, il Plateau potrebbe aver agito da rifugio biologico a partire dall’LGM, rappresentando quindi uno dei primi Nunatak Alpini mai documentati
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
Stocks, origin, and future trajectories of hidden soil organic carbon in paleosols of blockfields in the high alpine permafrost region
Full text linkPermafrost is warming because of global temperature increase, which alters the carbon cycle in these environments. While research has primarily focused on arctic permafrost, we are lacking data on the timing and magnitude of potential C accumulation and release in the alpine permafrost zone. These environments contain blockfields on mountain tops (>2900 m) with and without patterned ground, which are mainly vegetation free and therefore thought to be free of soil organic carbon (SOC). Motivated by the fact that coarse and fine material separates with freezing and thawing, we aimed to test whether alpine blockfields without vegetation are indeed SOC-free or whether they contain hidden carbon which might represent a CO2 source upon climatic warming. By sampling vegetated soils at the same or slightly lower elevation, we wanted to test how SOC stocks in blockfields will develop under climate warming in the near future.
On four mountain tops (2900 to 3200 m a.s.l.) in the periglacial zone of the Eastern Swiss and NorthWestern Italian Alps, we removed up to onemeter-deep thick stone layer and excavated eleven soil profiles. While one location was completely vegetation free, the three other locations were influenced by active patterned ground with non-vegetated and sparsely vegetated patches within the same blockfield.
At each site, we found dark and fine material beneath a stone cover of a few decimetres up to a meter. Preliminary results of the vegetation free location show a hidden SOC stock of 0.8 to 1.1 kgC·m-2 and narrow CN ratios of 9.0 to 10.1. Bulk soil 14C dating revealed an age of 4,000 to 12,900 years right beneath the stone cover (0-20 cm) and at greater depth (>80 cm) respectively. In agreement with our finding, Pintaldi et al. (2021)
observed “hidden” SOC stock beneath active patterned ground on a mountain top plateau in North-West Italy.
There are two possible origins of the hidden carbon: 1) soot deposition by natural and anthropogenic processes throughout the Holocene and 2) carbon accumulation during warmer climatic conditions during the early to middle Holocene
- …
