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posted to crn2076
by IAI
on 2013-04-30 20:17:47
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Revista Mexicana de Ciencias Forestales, Vol. 32, No. 1. (2007), pp. 9-37
posted to crn2047
by IAI
on 2013-04-30 20:11:17
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posted to crn2047
by IAI
on 2013-04-30 19:53:20
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posted to crn2047
by IAI
on 2013-04-30 19:51:42
Abstract
This paper presents absolute ages for flash floods and related sediment entrainment in headwater catchments to construct a spatiotemporal framework of process dynamics and locations of major areas of channel wall erosion. The most reliable method for dating erosion is through dendrogeomorphic studies of exposed tree roots. Based on the analysis of erosion signals in root-ring records we documented a time series of channel wall erosion and successfully dated 21 erosive flash flood events since A.D. 1870 in an ephemeral gully ...
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posted to crn2047
by IAI
on 2013-04-30 19:50:10
Abstract
A new tree-ring reconstruction of the Palmer Drought Severity Index (PDSI) for Mesoamerica from AD 771 to 2008 identifies megadroughts more severe and sustained than any witnessed during the twentieth century. Correlation analyses indicate strong forcing of instrumental and reconstructed June PDSI over Mesoamerica from the El Niño/Southern Oscillation (ENSO). Spectral analyses of the 1,238-year reconstruction indicate significant concentrations of variance at ENSO, sub-decadal, bi-decadal, and multidecadal timescales. Instrumental and model-based analyses indicate that the Atlantic Multidecadal Oscillation is important to ...
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posted to crn2047
by IAI
on 2013-04-30 19:48:45
Abstract
The lack of long-term records of productivity is a critical limitation to the study of ecosystem dynamics. Annual rings, a measure of growth in woody species, are a useful tool to document ecosystem dynamics. Time series of the Normalized Difference Vegetation Index (NDVI) provide estimates of ecosystem productivity through satellite-derived data on the fraction of photosynthetic active radiation absorbed by vegetation. In the Patagonian steppes, we relate changes in NDVI to interannual variations in the radial growth of the shrub Anarthrophyllum ...
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Revista Chilena de Historia Natural, Vol. 81 (2008), pp. 239-256
posted to crn2047
by IAI
on 2013-04-30 19:47:30
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Revista Española de Antropología Americana, Vol. 32 (2002), pp. 179-205
posted to crn2047
by IAI
on 2013-04-30 19:42:44
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posted to crn2047
by IAI
on 2013-04-30 19:38:41
Abstract
In most cases, gauged river flow records in southern South America extend for only a few decades, hampering the detection of long-term, decadal to centennial-scale cycles and trends. Long streamflow series can be reconstructed from tree-ring records, offering the opportunity of extending the limited hydrological instrumental data to several centuries. In northern Patagonia, Argentina, the Neuquén River has great importance for local and national socio-economic activities such as hydroelectric power generation, agriculture and tourism. In this study, new and updated tree-ring ...
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posted to crn2047
by IAI
on 2013-04-30 19:36:49
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Climate of the Past, Vol. 8 (2012), pp. 653-666
posted to crn2047
by IAI
on 2013-04-25 18:25:50
Abstract
Throughout the second half of the 20th century,the Central Andes has experienced significant climatic and environmental changes characterized by a persistent warming trend, an increase in elevation of the 0 C isotherm, and sustained glacier shrinkage. These changes have occurred in conjunction with a steadily growing demand for water resources. Given the short span of instrumental hydroclimatic records in this region, longer time span records are needed to understand the nature of climate variability and to improve the predictability of precipitation, a key ...
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posted to crn2047
by IAI
on 2013-04-25 18:19:31
along with 1 person
htwyw
Abstract
Castle Creek Glacier in the Cariboo Mountains of British Columbia remained close to its Little Ice Age limit for most of the past 1500 years, without significant recession until the 20th century. This conclusion is based on radiocarbon-dated detrital and in-situ plant material overrun by the glacier, and the sedimentary record from informally named On–off Lake, which received clastic sediments only when Castle Creek Glacier crossed a hydrologic divide 330 m upvalley of the Little Ice Age limit. Plant macrofossils recovered from ...
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posted to crn2047
by IAI
on 2013-04-25 18:17:14
Abstract
The Andean snowpack is the main source of freshwater and arguably the single most important natural resource for the populated, semi-arid regions of central Chile and central-western Argentina. However, apart from recent analyses of instrumental snowpack data, very little is known about the long term variability of this key natural resource. Here we present two complementary, annually-resolved reconstructions of winter snow accumulation in the southern Andes between 30°–37°S. The reconstructions cover the past 850 years and were developed using simple regression models ...
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Geographica Polonica, Vol. 81, No. 1. (2008), pp. 79-91
posted to crn2047
by IAI
on 2013-04-25 18:13:00
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Terra Glaciales, pp. 179-192
posted to crn2047
by IAI
on 2013-04-25 18:07:03
Abstract
The impact of climate change is affecting most Andean glaciers, that have lost ice mass and have visibly receded over the last hundred years. This retreat is generally diffused and has accelerated since the last decades. Some glaciers provide a very significant contribution (up to 70-80 % in years with scarce snowfall) to the annual flow of Argentinean rivers. In these regions, the reduced contribution of the glaciers will make the river flow more dependent upon seasonal snowfalls; years with scanty precipitation ...
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BOSQUE, Vol. 13, No. 23. (2012)
posted to crn2047
by IAI
on 2013-04-25 17:46:19
Abstract
The estimation of the forest and vegetation cover in the Valdivian Rainforest Eco-region (35º − 43º30´ S) of Chile in the Pre-European period emerges as a relevant scientific question due to its implications for forest conservation and for the improvement of the understanding of the patterns and dynamics of human settlement. This study uses a transdisciplinary approach integrating information from historical documents, archaeological evidence and the relationship of present vegetation with environmental variables. From this analysis we developed the first reconstruction of ...
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posted to crn2047
by IAI
on 2013-04-25 17:41:33
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BOSQUE, Vol. 32, No. 3. (2011), pp. 215-219
posted to crn2047
by IAI
on 2013-04-25 17:38:38
Abstract
Fire frequency and severity have increased in different regions of the world. The main causes explaining these new fire patterns would be associated with climate and land-use change. The present contribution briefly examines the recent changes of climate and predictions and their potential influence on fire activity in south-central Chile, along with the necessary adaptation measures to cope with this problem. Different studies coincide in that main effects of climate change in this area will be associated with lower precipitations which ...
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Surandino Monográfico, Vol. 1, No. 2. (2010)
posted to crn2047
by IAI
on 2013-04-25 17:34:43
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Trees, Vol. 23 (2009), pp. 1275-1284
posted to crn2047
by IAI
on 2013-04-24 19:20:52
Abstract
The lack of knowledge about species with well-delimited annual rings has hampered the development of dendrochronological records in the subtropical Chaco region of South America. In this contribution, we present the first tree-ring chronology of Schinopsis lorentzii Anacardiaceae), a dominant species in the semi-arid Chaco. Cross sections were collected near Las Lajitas, Salta, Argentina, and processed following the methods commonly used in dendrochronology. Annual growth variations between radii from a single individual and between radii from different trees were highly correlated. To determine the ...
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Vol. 2 (2008), pp. 27-52
posted to crn2047
by IAI
on 2013-04-24 19:13:26
Abstract
In the mid-20th Century, the Park and Front ranges of the Canadian Rocky Mountains contained approximately 1,500 individual glaciers whose melt water drains into the Nelson River system, which flows eastwards and empties into Hudson’s Bay. Using contemporary optical data obtained from space-based imaging sensors, we determined late 20th Century glacier volume changes and related them to river flow volumes. The results reveal significant small-glacier diminution during this period, and provide approximate ice wastage contributions relative to glacier extent.With reference to the results of companion ...
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posted to crn2047
by IAI
on 2013-04-24 19:05:16
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Agrofaz, Vol. 11, No. 4. (2011), pp. 95-100
posted to crn2047
by IAI
on 2013-04-24 18:55:47
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Revista Mexicana de Ciencias Agrícolas, No. 2. (2011), pp. 235-249
posted to crn2047
by IAI
on 2013-04-24 18:48:15
Abstract
The generation of paleoclimate series based on dendrochronological techniques, allows the historical analysis of climatic variability. Dendrochronology is an excellent alternative when the instrumental data bases of short extension are available, that limit to historically analyze its variability over time. The aim of this paper was to analyze the climatic variability over the past 600 years in northeastern Mexico, to determine the frequency of extreme hydroclimatic events (droughts)and their impact on society, using as proxy the growth rings of the species Pseudotsuga menziesi and ...
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Revista Mexicana de Ciencias Forestales, Vol. 2, No. 4. (2011), pp. 33-47
posted to crn2047
by IAI
on 2013-04-24 18:39:36
Abstract
In Sierra de Arteaga, Coahuila, Mexico, five Douglas-fir chronologies of earlywood, latewood and total ring width were developed from five mountain ranges (La Viga, El Coahuilón, El Tarillal, Los Pilares, and El Morro). To determine a common response for the chronologies a Principal Component Analysis was used. The first Eigenvalue (PC1) explained 72% (p<0.001) of the variance. The El Morro chronology showed the lowest correlation and was discarded from further analysis. A regional chronology was developed with the remaining chronologies, extending for the ...
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MAGALLANIA (Chile), 2011. Vol. 39(2):193-206, Vol. 39, No. 2. (2011), pp. 193-206
posted to crn2047
by IAI
on 2013-04-23 19:11:59
Abstract
Este trabajo presenta y caracteriza dos concentraciones de pilas de rocas identificadas en la margen sudoeste de la cuenca superior del río Santa Cruz (Argentina), en la Estancia Bon Accord. La edad mínima de estas estructuras es estimada a partir de análisis liquenométricos. Se recopila información sobre la existencia de este tipo de estructuras en la región patagónica. Por último, se discuten algunas de las funciones hipotéticas de estas acumulaciones utilizando casos arqueológicos locales y de otras partes del mundo. ...
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Ecología en Bolivia, Vol. 39, No. 1. (2004), pp. 5-24
posted to crn2047
by IAI
on 2013-04-23 19:05:04
Abstract
En este trabajo se analiza la potencialidad dendroclimatológica de Polylepis tarapacana (queñoa), pequeño arbolito que habita el Altiplano boliviano y zonas adyacentes de Perú, Chile y Argentina (16-22°S) entre los 4.000 y 5.200 m de altura. Muestras dendrocronológicas fueron colectadas sobre las laderas de cuatro volcanes: Sajama, Tunupa, Caquella y Soniquera. Hasta el presente, las cronologías varían entre 98 y 705 años de extensión y constituyen los registros dendrocronológicos más altos del mundo. Con el objeto de establecer los parámetros climáticos ...
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Lat. Am. J. Aquat. Research
posted to crn2076
by IAI
on 2013-04-17 16:23:27
Abstract
En este trabajo se presentan los resultados de un modelo hidrodinámico barotrópico de alta resolución no-lineal tridimensional para examinar la respuesta de los golfos norpatagónicos argentinos, San Matías (GSM), Nuevo (GN) y San José (GSJ), ante forzante de marea y patrones idealizados de viento superficial. La estructura de la circulación inducida por el viento predominante (Oeste) en los tres golfos consiste en dos giros independientes: uno anticiclónico en el Oeste con una corriente costera más intensa que fluye hacia el sur y un retorno más ...
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posted to crn2076
by IAI
on 2013-04-17 16:16:35
Abstract
Abstract In this study, observations and numerical simulations are used to investigate how different El Niño events affect the development of SST anomalies in the Atlantic and how this relates to the Brazilian northeast (NE) precipitation. The results show that different types of El Niño have different impacts on the SST anomalies of the equatorial and tropical South Atlantic but a similar SST response in the tropical North Atlantic. Strong and long (weak and short) El Niños with the main heating ...
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posted to crn2076
by IAI
on 2013-04-17 16:11:37
Abstract
In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume's waters and an offshore displacement of its salinity front. The interaction between tidal and wind-forcing reinforces ...
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posted to crn2076
by IAI
on 2013-04-17 16:09:03
Abstract
The trophic role of the hyperiid amphipod Themisto gaudichaudii in the southern Patagonian shelf food web was assessed from the analysis of stomach contents of the local fish assemblage. A total of 461 trawl samples were collected during seven seasonal cruises. A total of 17 out of 38 fish species were found to ingest T. gaudichaudii. This amphipod was a main prey item in five of these species, showing high values of alimentary index: Seriolella porosa (99.9%), Macruronus magellanicus (68.8%), Micromesistius ...
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Journal of Fluid Mechanics
posted to crn2076
by IAI
on 2013-04-17 16:06:12
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posted to crn2076
by IAI
on 2013-04-17 15:57:06
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posted to crn2076
by IAI
on 2013-04-17 15:53:48
Abstract
Marine benthic trophic relationships and food web structures may be influenced by benthic–pelagic coupling processes, which could also be intensified by the physical dynamics of marine fronts. In this work, we employed stable isotope (δ13C and δ15N) analysis to investigate the influence of the Southwest (SW) Atlantic shelf-break front (SBF; 38–39°S, 55–56°W; Argentina) on an epibenthic trophic web. Epibenthic organisms were sampled, at depths of ~ 100 m, with a non-selective dredge from a sandy bottom community located in frontal (F) and marginal ...
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GEOGACETA, Vol. 50, No. 2. (2011), pp. 145-148
posted to crn2076
by IAI
on 2013-04-16 19:49:45
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Marine Biology Research, Vol. 7 (2011), pp. 500-508
by V. González Carman, K. C. Álvarez, L. Prosdocimi, et al.M. C. Inchaurraga, R. F. Dellacasa, A. Faiella, C. Echenique, R. González, J. Andrejuk, H. W. Mianzan, C. Campagna, D. A. Albareda
posted to crn2076
by IAI
on 2013-04-16 19:24:38
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posted to crn2076
by IAI
on 2013-04-16 19:05:54
Abstract
Digenean are important endoparasites of fish with complex life cycles; some genera include medusae as secondary hosts. Their transmission to fish occurs when fish prey on these jelly hosts. Fish predation on jellyfish is a widespread phenomenon, even though predation by fish on jellyfish has not been determined through parasitism yet. We hypothesized that medusae with high prevalences of digeneans could be important for their transmission to fish. A total of 48,900 specimens of 50 medusa species were analyzed; 2,181 harbored ...
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Annals for Istrian and Mediterranean studies, series Historia Naturalis, Vol. 19(2, pp. 65-72
posted to crn2076
by IAI
on 2013-04-16 19:00:57
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Hydrobiologia, Vol. 616 (October 2009), pp. 99-111
posted to crn2076
by IAI
on 2013-04-16 15:34:29
Abstract
Acoustic techniques have been proposed as a new tool to assess jellyfish populations. However,the presence of mixed echoes from jellyfish and other organisms that share their distribution often prevent accurate estimates of their abundance and distribution being obtained. The isolated population of Aurelia inhabiting the Veliko Jezero (Big Lake-BL) of Mljet Island, in the South Adriatic Sea, offered a good opportunity to employ acoustic techniques to assess an entire jellyfish population. During October 2–5, 2006,combined video and acoustic methods were used in BL to determine ...
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posted to crn2076
by IAI
on 2013-04-16 15:23:43
Abstract
The seasonal cycle of the near-surface circulation off central Chile was analyzed using satellite altimetry and an oceanic model. To evaluate the role of the wind stress curl on the circulation we performed two identical simulations except for the wind-forcing: the “control run” used long-term monthly mean wind stress and the “no-curl run” used a similar wind stress field, but without curl. The observed and modeled (control run) surface currents showed a strong seasonal cycle and a well-defined equatorward flow with ...
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posted to crn2076
by IAI
on 2013-04-16 15:18:13
Abstract
The whitemouth croaker, Micropogonias furnieri, is exploited by coastal fisheries in the Plata estuary. Its age structure shows the predominance of certain year classes, which are indicative of recruitment variability. The estuary is affected by river discharge variations associated with climatic signals (El Niño Southern Oscillation and others). We hypothesize that recruitment may correlate: (i) negatively with runoff (low runoff would promote the stronger retention of ichthyoplankton); (ii) positively with temperature (higher temperatures should enhance larvae survivorship and/or expand the spawning ...
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Biogeochemistry (2012)
posted to crn2031
by IAI
on 2012-07-18 14:53:53
Abstract
Wetland ecosystems have a high carbon storage potential as a result of high primary productivity and low decomposition rates dictated by water ́ saturation. In the herbaceous wetlands of the Parana River Delta, drainage and afforestation with poplars represents one of the dominant land uses. We explored the effects of these interventions on the volume and carbon storage of the young sedimentary soils of the region. At three sites we identified paired stands occupying similar landscape positions and soil types but subject ...
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posted to crn2031
by IAI
on 2012-07-04 20:40:29
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posted to crn2031
by IAI
on 2012-07-04 20:33:29
Abstract
Dry subtropical regions, originally hosting xerophytic vegetation, are currently characterized by diverse land cover/use patterns. Using existing biophysical and socio-economic databases, we explored how human contexts influenced land cover, vegetation composition and agricultural production in five distant regions. On average, cultivated areas represented a minor proportion (<16%) of all the regions, except in Asia (74%). This proportion was positively associated with population density when considering all regions together (slope = 0.2 ha∗inh−1), but the association became weaker in low-population regions. While protected areas displayed ...
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International Journal of Remote Sensing (2011), pp. 1-25
posted to crn2031
by IAI
on 2012-07-04 20:30:19
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Ecosistemas, Vol. 17, No. 3. (2008), pp. 108-117
posted to crn2031
by IAI
on 2012-07-04 20:17:19
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posted to crn2017
by IAI
on 2012-07-04 19:54:39
Abstract
We use concurrent morning peak observations of carbon monoxide (CO) and nitrogen oxides (NOx) to evaluate mobile emissions estimates for CO and NOx at Bogotá (Colombia), Buenos Aires (Argentina), Santiago (Chile) and São Paulo (Brazil). In all cities, molar ratios of CO to NOx decrease over the last 10–15 years. These ratios are not captured by available inventories. Comparison among inventories suggests that major uncertainties are linked to inadequate emission factors for CO and inadequate activity data for NOx. These results, ...
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posted to crn2017
by IAI
on 2012-07-04 19:50:07
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posted to crn2014
by IAI
on 2012-06-01 18:35:36
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posted to crn2014
by IAI
on 2012-06-01 18:29:35
Abstract
A new ornamented species of the Glomeromycetes found in Pinar del Rio and Moa, western and east Cuba, respectively, is proposed here as Glomus crenatum. The fungus differs from previously described species by the darkly pigmented spore walls that possess a hemispherical dome-like surface ornamentation. ...
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