1,721,045 research outputs found
SiberianCrane_FrontiersInConservationScience
No full textCode and data for Increasing Arctic tundra flooding threatens wildlife habitat and survival: impacts on the critically endangered Siberian crane. This is for the paper,
Haverkamp, PJ, Bysykatova-Harmey, I, Germogenov, N, and Schaepman-Strub, G. 2022. Increasing Arctic tundra flooding threatens wildlife habitat and survival: impacts on the critically endangered Siberian crane. Frontiers in Conservation Science. https://doi.org/10.3389/fcosc.2022.79999
Towards spatial assessment of carbon sequestration in peatlands: spectroscopy based estimation of fractional cover of three plant functional types
Full text linkPeatlands accumulated large carbon (C) stocks as peat in historical times. Currently however, many peatlands are on the verge of becoming sources with their C sequestration function becoming sensitive to environmental changes such as increases in temperature, decreasing water table and enhanced nitrogen deposition. Long term changes in vegetation composition are both, a consequence and indicator of future changes in C sequestration. Spatial continuous accurate assessment of the vegetation composition is a current challenge in keeping a close watch on peatland vegetation changes. In this study we quantified the fractional cover of three major plant functional types (PFTs; Sphagnum mosses, graminoids, and ericoid shrubs) in peatlands, using field spectroscopy reflectance measurements (400–2400 nm) on 25 plots differing in PFT cover. The data was validated using point intercept methodology on the same plots. Our results showed that the detection of open Sphagnum versus Sphagnum covered by vascular plants (shrubs and graminoids) is feasible with an R2 of 0.81. On the other hand, the partitioning of the vascular plant fraction into shrubs and graminoids revealed lower correlations of R2 of 0.54 and 0.57, respectively. This study was based on a dataset where the reflectance of all main PFTs and their pure components within the peatland was measured at local spatial scales. Spectrally measured species or plant community abundances can further be used to bridge scaling gaps up to canopy scale, ultimately allowing upscaling of the C balance of peatlands to the ecosystem level
A new lab facility for measuring bidirectional reflectance/emittance distribution functions of soils and canopies
No full textRecently, a laboratory measurement facility has been realized for assessing the anisotropic reflectance and emittance behaviour of soils, leaves and small canopies under controlled illumination conditions. The facility consists of an ASD FieldSpec 3 spectroradiometer covering the spectral range from 350 – 2500 nm at 1 nm spectral sampling interval. The spectroradiometer is deployed using a fiber optic cable with either a 1°, 8° or 25° instantaneous field of view (IFOV). These measurements can be used to assess the plant pigment (chlorophyll, xanthophyll, etc.) and non-pigment system (water, cellulose, lignin, nitrogen, etc.). The thermal emittance is measured using a NEC TH9100 Infrared Thermal Imager. It operates in a single band covering the spectral range from 8 – 14 mm with a resolution of 0.02 K. Images are 320 (H) by 240 (V) pixels with an IFOV of 1.2 mrad. A 1000 W Quartz Tungsten Halogen (QTH) lamp is used as illumination source, approximating the radiance distribution of the sun. This one is put at a fixed position during a measurement session. Multi-angular measurements are achieved by using a robotic positioning system allowing to perform either reflectance or emittance measurements over almost a complete hemisphere. The hemisphere can be sampled continuously between 0° and 80° from nadir and up to a few degrees from the hot-spot configuration (depending on the IFOV of the measurement device) for a backscattering target. Measurement distance to targets can be varied between 0.25 and 1 m, although with a distance of more than 0.6 m it is not possible to cover the full hemisphere. The goal is to infer the BRDF (bidirectional reflectance distribution function) and BTDF (bidirectional thermal distribution function) from these multi-angular measurements for various surface types (like soils, agricultural crops, small tree canopies and artificial objects) and surface roughness. The steering of the robotic arm and the reading of the spectroradiometer and the thermal camera are all fully automated
Scaling spectroscopic approaches – from leaf albedo to ecosystems mapping
Full text linkField based spectroscopy for ecological and environmental monitoring has become an indispensable part of complete observational systems as defined in GEOSS (Global Earth Observation System of Systems). Spectral scaling approaches are currently ranging from molecular to ecosystem or even biome scales. We discuss the use of field spectroscopy in relation to supporting large-scale ecosystem and ecotone inventorying, in particular the retrieval of biochemical and structural attributes of vegetation. First, attention will be put on using an object-relational database for the structured compilation of field spectral measurements and corresponding metadata. Spectral libraries have been collected over a wide variety of natural and man-made targets and their sampling scheme is discussed. Second, recent advances in reflectance and radiance terminology for field spectrometers are discussed, propagating the use of spectral albedo. Advanced measurement instrumentation and facilities are presented that complement solar reflective measurements with the angular, thermal and plant fluorescence domains. Further, experiments measuring leaf albedo, transmittance and absorbtance are discussed using examples from a wide range of ecosystems and their ecotones. Finally, we discuss scaling approaches from field measurements to airborne and spaceborne mapping methods, demonstrating the wide use of field spectrometers for environmental applications. We conclude on the importance of using field spectrometers over the past one and a half decades at our institutions
Die Arktis unter Druck Menschgemachter Wandel in der Arktis und die Rolle der Schweiz
No full textDie Arktis leidet besonders stark unter dem Klimawandel und der Umweltverschmutzung. Während das arktische «Tauwetter» die Lebensgrundlagen der indigenen Bevölkerung gefährdet, sehen die Industrieländer darin eine Chance für neue wirtschaftliche Aktivitäten. Die Veränderungen in der Arktis wirken sich aber auch global aus. Deshalb ist eine Bewahrung der arktischen Öko- und Klimasysteme für die nachhaltige Entwicklung ausserhalb der Arktis essenziell – auch in der Schweiz.Fischer H, Chanteloup L, Csonka Y, Holm P, Jaccard S, Schaepman-Strub G, Schmale J, Vieli A (2022) Die Arktis unter Druck. Menschgemachter Wandel in der Arktis und die Rolle der Schweiz. Swiss Academies Reports 17 (4
Land Surface Reflectance Definitions and Terminology, Land Surface Albedo Description : Response to GEO Task AR-07-01, Standards and Interoperability Forum (SIF), Call for Participation (CFP)
No full textGoing 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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