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Thermal remote sensing of ice-debris landforms using ASTER  [PDF]
A. Brenning,M. A. Pe?a,S. Long,A. Soliman
The Cryosphere Discussions , 2011, DOI: 10.5194/tcd-5-2895-2011
Abstract: Remote sensors face challenges in characterizing mountain permafrost and ground thermal conditions or mapping rock glaciers and debris-covered glaciers. We explore the potentials of thermal imaging and in particular thermal inertia mapping in mountain cryospheric research, focusing on the relationships between ground surface temperatures and the presence of ice-debris landforms on one side and land surface temperature (LST) and apparent thermal inertia (ATI) on the other. In our case study we utilize ASTER daytime and nighttime imagery and in-situ measurements of near-surface ground temperature (NSGT) in the Mediterranean Andes during a snow-free and dry observation period in late summer. Spatial patterns of LST and NSGT were mostly consistent with each other both at daytime and at nighttime. Daytime LST over ice-debris landforms was decreased and ATI consequently increased compared to other debris surfaces under otherwise equal conditions, but NSGT showed contradictory results, which underlines the complexity and possible scale dependence of ATI in heterogeneous substrates with the presence of a thermal mismatch and a heat sink at depth. While our results demonstrate the utility of thermal imaging and ATI mapping in a mountain cryospheric context, further research is needed for a better interpretation of ATI patterns in complex thermophysical conditions
Parasite loads and altitudinal distribution of Liolaemus lizards in the central Chilean Andes
CAROTHERS,JOHN H.; JAKSIC,FABIáN M.;
Revista chilena de historia natural , 2001, DOI: 10.4067/S0716-078X2001000300013
Abstract: this study compared the distributions of ten species of liolaemus lizards in the central chilean andes to the distributions of four types of parasites: malaria-causing plasmodium, gut nematodes, ticks, and mites. we wanted to see if parasite numbers might be a factor in determining distributional limits of the lizards. we found that there was no evidence of malarial infestation of the lizards, that ticks were almost absent, that more often than not mite numbers decreased at the distributional limits of the lizards, and that gut nematodes confined to the herbivorous lizards in our sample may well be beneficial rather than detrimental. rather than parasitism, other biotic interactions (e.g., predation or competition) are more likely candidates as factors influencing lizard elevational distributions, as are abiotic characteristics such as microhabitat availabilities and thermal factors
Residuos le osos de gran tama o en un torrente de la Cordillera de Los Andes, Chile: su funcionalidad e importancia Study on large woody debris in a stream from the Andes Mountains: functionality and importance  [cached]
Andrea Andreoli,Giovanni Carlig,Francesco Comiti,Andrés Iroumé
Bosque (Valdivia) , 2007,
Abstract: Se registraron la cantidad, características e impacto morfológico de los residuos le osos de gran tama o (large woody debris o LWD) en el torrente Tres Arroyos, situado en la Cordillera de Los Andes, Chile, cuya cuenca alta está cubierta por bosques primarios de los géneros Araucaria y Nothofagus. Se examinaron los residuos le osos de más de 10 centímetros de diámetro y 1 m de longitud, en un tramo de 1,5 km del cauce principal del torrente que presenta una morfología general de step-pool/cascade. La cantidad de LWD en el cauce y sus márgenes inundables fue de 1.500 m3/ha, valor comparable a los registrados en cuencas con bosques antiguos en la costa noroeste de América del Norte. Casi dos tercios del volumen de LWD formaban acumulaciones de troncos y la mitad de ellos se encontraron en las márgenes inundables activas del torrente. El 83% del LWD presentaba se ales de haber sido movilizado por el torrente, el 13% se asociaba a caídas naturales de árboles y el resto a aportes por deslizamientos y erosión de laderas. Se observaron diversos tipos de acumulaciones de troncos que alteraban la morfología del canal y cubrían las márgenes del cauce. Se estimó que las acumulaciones de LWD en el tramo estudiado disipan el 27% de la energía potencial total de la corriente de agua. Finalmente, se estimó en 2.000 m3 el volumen de sedimentos depositados en el cauce principal aguas arriba de cúmulos de LWD, correspondiendo aproximadamente al 150% del aporte anual total de sedimentos sólidos de la cuenca. The study analyzed amounts, characteristics and morphological impact of large woody debris (LWD) in Tres Arroyos torrent of the Chilean Southern Andes draining an old-growth forested basin. All woody debris pieces greater than 10 cm in diameter and 1 m in length were surveyed along a 1.5 km-long stream section presenting a general step-pool/cascade morphology. The total amount of large woody debris within the fluvial corridor was on average 1,500 m3/ha, very high value comparable only to data from old-growth forested basins in the Pacific Northwest of North America. Around two thirds of LWD volume were found in accumulations while half of the LWD elements were located on the active floodplain. As much as 83% of the LWD pieces showed signs of in-stream transport, 13% were directly associated to natural tree falls, and the remaining to landslides and bank erosion. Different types of log-jams were observed, some heavily altering channel morphology (log-steps and valley jams), others just lining the channel edges (bankfull bench jams). The percentage of log-steps over the
Recent variation of the Las Vacas Glacier Mt. Aconcagua region, Central Andes, Argentina, based on ASTER stereoscopic images
M. G. Lenzano, J. C. Leiva,L. Lenzano
Advances in Geosciences (ADGEO) , 2009,
Abstract: This work presents the results of the ASTER stereoscopic image processing to calculate the volume changes of Las Vacas Glacier. The processing of medium resolution satellite images (ASTER level 1A – pixel 15 m) from February 2001 and 2007 was performed applying the satellite digital photogrammetry method (K b, 2005). The comparison of the two generated DTM returns results that are acceptable within the parameters and precisions that can be obtained with this kind of sensor and the processing methodology.
Compositional variations revealed by ASTER image analysis of the Viedma Volcano, southern Andes Volcanic Zone
Kobayashi,Chiaki; Orihashi,Yuji; Hiarata,Daiji; Naranjo,José A; Kobayashi,Makoto; Anma,Ryo;
Andean geology , 2010,
Abstract: we conducted a lithological mapping of the viedma volcano, one of five volcanoes in the andean austral volcanic zone (avz), using remote sensing techniques. we used data of the advanced spaceborne thermal emission and reflection radiometer (aster) sensor which is highly effective in geological research, to understand build-up processes and to deduce compositional variation of the viedma volcano emerging from the south patagonian ice field. the volcanic edifice was divided into bright parts that mainly compose the eastern flank of the volcano and dark parts at the central crater area based on the observation in visible and near infrared ranges. the sio2 concentration was cal-culated using the bands in the visible and thermal infrared regions. the dark part and the bright part have approximately 51 wt% and 63 wt% average sio2 content respectively, indicating that the exposures of the viedma volcano have a wide variation in sio2 concentration. although, according to other authors, ejecta from the viedma volcano have 64-66 wt% sio2 and other av z volcanoes are essentially monolithologic dacite/andesite volcanoes, the edifice of the viedma volcano appears to be composed mostly of basalts or older rocks/basement with low silica contents.
Environmental factors affect the spatial arrangement of survival and damage of outplanted nothofagus dombeyi seedlings in the chilean andes
Soto,Daniel P; Donoso,Pablo J; Uteau,Daniel; Zú?iga-Feest,Alejandra;
Interciencia , 2009,
Abstract: mortality patterns were analyzed in a one-year old nothofagus dombeyi plantation at mid-elevation in the chilean andes. ripley′s univariate function was used to detect spatial patterns of mortality and damage (as reflected in crown dieback) of seedlings by assigning them into four categories: no crown damage, 1/3 of the crown damaged, 2/3 of the crown damaged and dead. through correspondence analysis, variables (plant attributes, topography, weed competition, neighboring vegetation and fertilization) that could affect mortality were tested. at the end of the first growing season 67% of the seedlings survived, and by the end of the following dormant season only 37% were alive. mortality patterns were random for seedlings with 1/3 of the crown damaged, and clustered for all other categories. environmental variables with the greatest influence on mortality were increasing distance to a neighboring 10m tall plantation, absence of tall vegetation cover and convex micro-topography. results suggest that large temperature oscillations with events of freezing temperatures (defined as the reported lethal temperature for 50% of its leaves) during the growing season, and severe frost during the dormant season, were the main causes of mortality and damage. the convenience of providing seedlings with some shelter when outplanted, or with an appropriate cold-acclimation treatment to resist low freezing temperatures when outplanted in open fields in harsh cold regions of the south-central andes is discussed.
Compositional variations revealed by ASTER image analysis of the Viedma Volcano, southern Andes Volcanic Zone Variaciones composicionales reveladas mediante análisis de imágenes ASTER del volcán Viedma, Zona Volcánica Andina Austral  [cached]
Chiaki Kobayashi,Yuji Orihashi,Daiji Hiarata,José A Naranjo
Andean Geology , 2010,
Abstract: We conducted a lithological mapping of the Viedma volcano, one of five volcanoes in the Andean Austral Volcanic Zone (AVZ), using remote sensing techniques. We used data of the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) sensor which is highly effective in geological research, to understand build-up processes and to deduce compositional variation of the Viedma volcano emerging from the South Patagonian ice field. The volcanic edifice was divided into bright parts that mainly compose the eastern flank of the volcano and dark parts at the central crater area based on the observation in visible and near infrared ranges. The SiO2 concentration was cal-culated using the bands in the visible and thermal infrared regions. The dark part and the bright part have approximately 51 wt% and 63 wt% average SiO2 content respectively, indicating that the exposures of the Viedma volcano have a wide variation in SiO2 concentration. Although, according to other authors, ejecta from the Viedma volcano have 64-66 wt% SiO2 and other AV Z volcanoes are essentially monolithologic dacite/andesite volcanoes, the edifice of the Viedma volcano appears to be composed mostly of basalts or older rocks/basement with low silica contents. Mediante el uso de técnica de sensoría remota se ha desarrollado un mapeo litológico del volcán Viedma, uno de los cinco volcanes de la Zona Volcánica Andina Austral (ZVA). Para este efecto, se ha utilizado el radiómetro ‘Advanced Spaceborne Thermal Emission and Reflection’ (ASTER) que es muy efectivo en investigación geológica, para entender los procesos que han controlado la estructura y deducir las variaciones composi-cionales del volcán Viedma, que sobresale levemente de la superficie del campo de hielo Patagónico Sur. Sobre la base de la observación en el intervalo del espectro visible e infrarrojo cercano, en el edificio se distinguen partes brillantes que corresponden al flanco oriental del volcán y partes oscuras en el área del cráter central. La concentración de SiO2 se calculó a través del uso de las bandas en las regiones visibles e infrarrojo termal. Las partes oscura y brillante tienen un promedio aproximado de 51% y 63% de SiO2 en peso, respectivamente, lo que indica que el volcán Viedma expone una amplia diferenciación de las concentraciones de SiO2. Aunque, según otros autores, las muestras analizadas de material piroclástico del volcán Viedma tienen contenidos de 64-66% SiO2 y que otros aparatos de la ZVA son volcanes esencialmente monolitológicos dacíticos/andesíticos, el edificio del volcán Viedma estaría c
FLORA Y VEGETACION DEL SALAR DE ASCOTAN, ANDES DEL NORTE DE CHILE FLORA AND VEGETATION OF ASCOTAN SALTMARSH, NORTHERN CHILEAN ANDES  [cached]
Sebastián Teillier,Pablo Becerra
Gayana. Botanica , 2003,
Abstract: En este trabajo se caracterizan la flora y la vegetación del salar de Ascotán, ubicado en los Andes de la Región de Antofagasta (II), Chile. La flora del salar, compuesta por 21 especies, es completamente diferente de la flora aleda a a él. También difieren los espectros de formas de vida del salar, dominado por hemicriptófitas (hierbas perennes), con la vegetación que lo rodea, dominada por nanofanerófitas (arbustos). En el salar se encontraron dos unidades de vegetación diferenciadas a partir por la composición de especies. Ambas unidades difieren, tanto en su flora como en sus espectros biológicos. Una unidad está dominada por hemicriptófitas y caméfitas, mientras que en la otra dominan exclusivamente las hemicriptófitas; las caméfitas y las geófitas poseen menor importancia. Factores edáficos probablemente pueden explicar las diferencias vegetacionales entre el salar y sus alrededores, como la presencia de dos unidades vegetacionales dentro del salar In this paper we characterise the flora and vegetation of Ascotan saltmarsh, located in the Andes of northern Chile. The saltmarsh flora, comprising 21 species, is completely different from the flora of surrounding slopes, differing not only in species composition but also in lifeform spectrum. The saltmarsh is dominated by hemicryptophytes, whereas nanophanerophytes predominate on the slopes. A cluster analysis distinguished two vegetation types within the saltmarsh, differing in species composition and in representation of chamaephytes, geophytes and hemicriptophytes. Substrate variation probably accounts for differences between the saltmarsh vegetation and its surrounding sites, as well as the existence of two vegetation types within the salar
Symbolic landforms created by ancient earthworks near Lake Titicaca  [PDF]
Amelia Carolina Sparavigna
Physics , 2010,
Abstract: Interesting landforms created by an ancient network of earthworks are shown, using Google satellite imagery enhanced by an image processing. This network covers a large part of the land near the Titicaca Lake. Satellite images clearly display the slopes of hills criss-crossed with terrace walls and the surfaces of the plains covered with raised fields, indicating that this was once a highly productive agricultural place for the south central Andes. Some of the landforms are rather remarkable, having a clear symbolic function. Among them, there are structures which seem to represent birds, where ponds are their eyes.
Parasite loads and altitudinal distribution of Liolaemus lizards in the central Chilean Andes Cargas parasitarias y distribución de lagartijas Liolaemus en los Andes de Chile central
JOHN H. CAROTHERS,FABIáN M. JAKSIC
Revista chilena de historia natural , 2001,
Abstract: This study compared the distributions of ten species of Liolaemus lizards in the central Chilean Andes to the distributions of four types of parasites: malaria-causing Plasmodium, gut nematodes, ticks, and mites. We wanted to see if parasite numbers might be a factor in determining distributional limits of the lizards. We found that there was no evidence of malarial infestation of the lizards, that ticks were almost absent, that more often than not mite numbers decreased at the distributional limits of the lizards, and that gut nematodes confined to the herbivorous lizards in our sample may well be beneficial rather than detrimental. Rather than parasitism, other biotic interactions (e.g., predation or competition) are more likely candidates as factors influencing lizard elevational distributions, as are abiotic characteristics such as microhabitat availabilities and thermal factors Este estudio compara las distribuciones de diez especies de lagartijas Liolaemus en los Andes de Chile central, con las distribuciones de cuatro tipos de parásitos: Plasmodium causantes de malaria, nemátodos intestinales, garrapatas y ácaros. Quisimos verificar si los números de parásitos pudieran ser un factor determinante de los límites de distribución de las lagartijas. Encontramos que no había evidencia de infestación por malaria en las lagartijas; que las garrapatas estaban casi ausentes; que los números de ácaros más a menudo decrecían que aumentaban en los límites distribucionales de las lagartijas; y que los nemátodos intestinales confinados a las lagartijas herbívoras en nuestra muestra bien podían ser beneficiosos antes que da inos. Más bien que parasitismo, otras interacciones bióticas (e.g., depredación o competencia) son candidatos más probables como factores que influyen las distribuciones altitudinales de las lagartijas, además de características abióticas tales como la disponibilidad de microhábitats y los factores térmicos
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