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Combining potentially incompatible community datasets when harmonizing forest inventories in subarctic Alaska, USA / Robert J. Smith in Journal of vegetation science, vol 30 n° 1 (January 2019)  

Public [article]  inJournal of vegetation science > vol 30 n° 1 (January 2019) . - pp 18 - 29 Titre : Combining potentially incompatible community datasets when harmonizing forest inventories in subarctic Alaska, USA Type de document : Article/Communication Auteurs : Robert J. Smith, Auteur ; Andrew N. Gray, Auteur Année de publication : 2019 Article en page(s) : pp 18 - 29 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] Alaska (Etats-Unis) [Termes descripteurs IGN] forêt boréale [Termes descripteurs IGN] inventaire forestier (techniques et méthodes) [Termes descripteurs IGN] inventaire forestier étranger (données) [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] variabilité [Vedettes matières IGN] Inventaire forestier Résumé : (auteur) Aims : Plant responses to disturbances and environmental variation can manifest in communities as compositional nestedness (i.e., one community is a subset of another) and/or turnover (two communities represent different compositional gradient spaces). Yet, different sampling designs can artificially give an illusion of such compositional differences among two datasets, making it problematic to harmonize them in multi‐species analysis. We test the prediction that sampling differences which increase beta‐diversity components (nestedness and turnover) among two vegetation datasets will decrease their exchangeability. Location : Boreal forests of Tanana River region, interior Alaska, USA. Methods : We develop novel methods for comparing compositional variation among two datasets in nonmetric multidimensional scaling (NMDS) ordination. Resampled NMDS establishes internal sampling variability for each dataset independently, and reciprocal NMDS determines external exchangeability when the two are mutually exchanged. We first compare simulated data with specified beta‐diversity differences, then evaluate two forest inventories based on local vs regional sampling designs in Alaska's boreal forests. Results : As simulated species turnover and nestedness increased, internal sampling variability remained essentially constant, but external exchangeability progressively declined. Species turnover (not nestedness) had the larger negative effect on exchangeability. Among the boreal forest inventories, internal sampling variability was relatively similar, and exchangeability was weakly moderate, but the regional inventory exhibited much better fit to broad‐scale environment. Species turnover (not nestedness) contributed the majority of beta‐diversity differences among the two forest inventories, suggesting that strong environmental gradients were unequally represented. Conclusions : Species turnover alters multivariate outcomes more drastically than species nestedness. Therefore, combining two vegetation datasets may be inadvisable when turnover prevails. Instead, a multi‐scale perspective, with separate but complementary forest inventory analyses, can portray local and regional variation at appropriate scales. Our method is tractable for assessing exchangeability of potentially inconsistent sampling designs, like those that are common in synthesis studies and long‐term ecological monitoring. Numéro de notice : A2019-373 Thématique : FORET Nature : Article DOI : 10.1111/jvs.12694 date de publication en ligne : 07/11/2018 En ligne : https://doi.org/10.1111/jvs.12694 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93412 [article]

Integrating SAR and derived products into operational volcano monitoring and decision support systems / Franz J. Meyer in ISPRS Journal of photogrammetry and remote sensing, vol 100 (February 2015)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 100 (February 2015) . - pp 106 - 117 Titre : Integrating SAR and derived products into operational volcano monitoring and decision support systems Type de document : Article/Communication Auteurs : Franz J. Meyer, Auteur ; D.B. McAlpin, Auteur ; W. Gong, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 106 - 117 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] Alaska (Etats-Unis) [Termes descripteurs IGN] détection de changement [Termes descripteurs IGN] éruption volcanique [Termes descripteurs IGN] gestion des risques [Termes descripteurs IGN] image radar moirée [Termes descripteurs IGN] intégration de données [Termes descripteurs IGN] séisme [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] surveillance géologique [Termes descripteurs IGN] volcan Résumé : (auteur) Remote sensing plays a critical role in operational volcano monitoring due to the often remote locations of volcanic systems and the large spatial extent of potential eruption pre-cursor signals. Despite the all-weather capabilities of radar remote sensing and its high performance in monitoring of change, the contribution of radar data to operational monitoring activities has been limited in the past. This is largely due to: (1) the high costs associated with radar data; (2) traditionally slow data processing and delivery procedures; and (3) the limited temporal sampling provided by spaceborne radars. With this paper, we present new data processing and data integration techniques that mitigate some of these limitations and allow for a meaningful integration of radar data into operational volcano monitoring decision support systems. Specifically, we present fast data access procedures as well as new approaches to multi-track processing that improve near real-time data access and temporal sampling of volcanic systems with SAR data. We introduce phase-based (coherent) and amplitude-based (incoherent) change detection procedures that are able to extract dense time series of hazard information from these data. For a demonstration, we present an integration of our processing system with an operational volcano monitoring system that was developed for use by the Alaska Volcano Observatory (AVO). Through an application to a historic eruption, we show that the integration of SAR into systems such as AVO can significantly improve the ability of operational systems to detect eruptive precursors. Therefore, the developed technology is expected to improve operational hazard detection, alerting, and management capabilities. Numéro de notice : A2015-057 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://www.sciencedirect.com/science/article/pii/S0924271614001270 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75311 [article]

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Illustrating the temporal progress of environmental change / Joann W. Harvey in Photogrammetric Engineering & Remote Sensing, PERS, vol 79 n° 12 (December 2013)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 79 n° 12 (December 2013) . - pp 1159 - 1170 Titre : Illustrating the temporal progress of environmental change Type de document : Article/Communication Auteurs : Joann W. Harvey, Auteur ; Edwin J. Green, Auteur Année de publication : 2013 Article en page(s) : pp 1159 - 1170 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes descripteurs IGN] Alaska (Etats-Unis) [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] détection de changement [Termes descripteurs IGN] image NOAA-AVHRR [Termes descripteurs IGN] nébulosité Résumé : (Auteur) Remotely sensed Advanced Very High Resolution Radiometer (AVHRR) images, collected during the northern Alaskan growing seasons of 1995 through 2011, and a Bayesian Regression Tree modeling method were brought together, with two novel ideas, to characterize year-to-year environmental change in a multivariate feature space (vegetation, temperature, precipitable water, and cloud cover). The method used collection year as the "response" variable, and the algorithm was applied in two stages to reduce the effects of cloud cover upon the results and to reveal the temporal distribution of cloudy conditions. The analysis identified a shift in environmental conditions between 2003 and 2004 when cloudy and wet conditions were replaced by clear and dry conditions. Gradual changes that occurred throughout the study period were also detected. The analysis also confirmed that it could detect that region's recent (2007, 2010, 2011) warming associated with sea ice melting. Numéro de notice : A2013-692 Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.79.12.1159 En ligne : https://doi.org/10.14358/PERS.79.12.1159 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32828 [article]

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Landscape controls over major nutrients and primary productivity of Arctic lakes / P. Pathak in Cartography and Geographic Information Science, vol 39 n° 4 (October 2012)  

Public [article]  inCartography and Geographic Information Science > vol 39 n° 4 (October 2012) . - pp 187 - 198 Titre : Landscape controls over major nutrients and primary productivity of Arctic lakes Type de document : Article/Communication Auteurs : P. Pathak, Auteur ; R. Stine, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 187 - 198 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] Alaska (Etats-Unis) [Termes descripteurs IGN] Arctique [Termes descripteurs IGN] azote [Termes descripteurs IGN] bassin hydrographique [Termes descripteurs IGN] chlorophylle [Termes descripteurs IGN] flore aquatique [Termes descripteurs IGN] flore ripicole [Termes descripteurs IGN] image radar [Termes descripteurs IGN] image SPOT [Termes descripteurs IGN] interaction spatiale [Termes descripteurs IGN] lac [Termes descripteurs IGN] marais [Termes descripteurs IGN] occupation du sol [Termes descripteurs IGN] phosphore [Termes descripteurs IGN] productivité [Termes descripteurs IGN] surveillance [Termes descripteurs IGN] zone tampon Résumé : (Auteur) Increasing surface temperatures in the Arctic are affecting the dynamics between lakes and their landscapes. In this paper, we use landscape metrics for land cover and statistical analysis to explore the interactions between such measures as shape and patch density indices for land cover and lake primary productivity. The objective was to identify metrics that could be used to predict lake primary productivity, as measured by chlorophyll a, total nitrogen and total phosphorus estimates. Land cover and landscape metrics for the Toolik region of Alaska were derived using satellite imagery and Fragstats software. The metrics, treated as independent variables in a stepwise regression, were derived for two levels of land cover. The first comprised the entire watershed studied; the second was derived using buffers created around water channels within each watershed. A statistically significant model for each dependent variable was obtained. Results suggest that, of the metrics tested; those related to broad leaf vegetation complexes were most useful in predicting lake primary productivity. The Landscape Shape Index for riparian patches and the Patch Density for heath complex were the two most important metrics for predicting variation in chlorophyll a (p Numéro de notice : A2012-574 Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1559/15230406394187 En ligne : https://doi.org/10.1559/15230406394187 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32020 [article]

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Producing an indigenous knowledge Web GIS for Arctic Alaska communities: Challenges, successes, and lessons learned / W. Eisner in Transactions in GIS, vol 16 n° 1 (February 2012)  

Public [article]  inTransactions in GIS > vol 16 n° 1 (February 2012) . - pp 17 - 37 Titre : Producing an indigenous knowledge Web GIS for Arctic Alaska communities: Challenges, successes, and lessons learned Type de document : Article/Communication Auteurs : W. Eisner, Auteur ; J. Jelacic, Auteur ; C. Cuomo, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 17 - 37 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes descripteurs IGN] Alaska (Etats-Unis) [Termes descripteurs IGN] Arctique [Termes descripteurs IGN] SIG participatif [Termes descripteurs IGN] WebSIG Résumé : (Auteur) A traditional knowledge “Iñupiaq Web GIS”, based on a five-year study and containing observations and environmental knowledge of Iñupiat communities indigenous to Arctic Alaska, was incorporated into a Web-based platform. The website, “Arctic Cultural Cartography,” was created to be an open portal through which the password-protected “Iñupiaq Web GIS” could be accessed. We discuss the process of developing the web GIS including the incorporation of user-friendly features such as links to interactive maps, video clips of interviews, discussion boards, and the integration of popular web interfaces such as Facebook. We also discuss short- and long-term goals for the further development of the GIS, its potential as a sustainable, participatory online database for sharing pertinent ecological knowledge, and challenges in achieving optimal community involvement given constraints imposed by remote locations with limited bandwidth. Numéro de notice : A2012-096 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1467-9671.2011.01291.x/pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31544 [article]

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Mapping vegetated wetlands of Alaska using L-band radar satellite imagery / Jane Whitcomb in Canadian journal of remote sensing, vol 35 n° 1 (February 2009)

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DEM control in Arctic Alaska with Icesat laser altimetry / D.K. Atwood in IEEE Transactions on geoscience and remote sensing, vol 45 n° 11 Tome 2 (November 2007)

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InSAR imaging of volcanic deformation over cloud-prone areas: Aleutian islands / Zhong Lu in Photogrammetric Engineering & Remote Sensing, PERS, vol 73 n° 3 (March 2007)

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March2003 EOS aqua AMSR-E sea ice field campaign / D.J. Cavalieri in IEEE Transactions on geoscience and remote sensing, vol 44 n° 11 Tome 1 (November 2006)

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Bases de données ethnographiques / Françoise de Blomac in SIG la lettre, n° 76 (avril 2006)

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Derivation of a threshold function for the advanced very high resolution radiometer 3, 75um channel and its application in automatic cloud discrimination over snow/ice surfaces / X. Xiong in International Journal of Remote Sensing IJRS, vol 25 n° 15 (August 2004)

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Geodetic Activities, Juneau Icefield, Alaska, 1981-1996 / W.M. Welsch (1997)

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Contributions of space geodesy to geodynamics / D.E. Smith (1993)

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An automated system for mosaicking spaceborne SAR imagery / R. Kwok in International Journal of Remote Sensing IJRS, vol 11 n° 2 (February 1990)

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Mapping arctic tundra vegetation types using digital Spot HRV-XS / D. Stow in International Journal of Remote Sensing IJRS, vol 10 n° 8 (August 1989)

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