Papers by Fernando Torrejón
Revista de geografía Norte Grande, 2011
En este trabajo se estimó la pérdida y fragmentación de bosque nativo en la cuenca del río Aysén,... more En este trabajo se estimó la pérdida y fragmentación de bosque nativo en la cuenca del río Aysén, ocurrida entre los años 1900 y 1998, debido principalmente a incendios forestales producto de la colonización del territorio. En la reconstrucción de la cobertura boscosa fueron de gran utilidad distintos registros históricos y el sistema de información geográfica (SIG ArcView 3.2). Se aplicaron diferentes índices del paisaje (área, densidad y tamaño del fragmento, área núcleo total, distancia euclidiana, índices de forma y de agregación, y longitud de borde total), evaluándose los cambios en los patrones de distribución del bosque nativo entre 1900 y 1998. Se reconoció que el bosque perdido fue reemplazado mayormente por praderas, evidenciándose una pérdida aproximada del 23%, de bosque nativo, identificándose además un aumento de fragmentos menores a 100 ha, y la disección de estos debido a los incendios generados durante la colonización. Sin embargo, dichos fragmentos presentarían una alta conectividad, situación que fue corroborada a través de diferentes índices de paisaje.
Journal of South American Earth Sciences, 2012
Historical earthquakes of Chile's metropolitan region include a previously uncatalogued earthquak... more Historical earthquakes of Chile's metropolitan region include a previously uncatalogued earthquake that occurred on 7 August 1580 in the Julian calendar. We found an authoritative account of this earthquake in a letter written four days later in Santiago and now archived in Spain. The letter tells of a destructive earthquake that struck Santiago and its environs. In its reported effects it surpassed the one in the same city in 1575, until now presumed to be the only earthquake in the first century of central Chile's written history. It is not yet possible to identify the source of the 1580 earthquake but viable candidates include both the plate boundary and Andean faults at shallows depths around Santiago. By occurring just five years after another large earthquake, the 1580 earthquake casts doubt on the completeness of the region's historical earthquake catalog and the periodicity of its large earthquakes. That catalog, based on eyewitness accounts compiled mainly by Alexander Perrey and Fernand Montessus de Ballore, tells of large Chile's metropolitan region earthquakes in 1575, 1647, 1730, 1822, 1906 and 1985. The addition of a large earthquake in 1580 implies greater variability in recurrence intervals and may also mean greater variety in earthquake sources.
Environmental Pollution, 2006
The lake sediment record of SCPs shows the record of fossil-fuel derived pollution in Central Chile.
Revista de Geografia Norte Grande
Intervención Ambiental Temprana en una Localidad .ronteriza de la Araucanía (S. XVI-XIX) RESUMEN ... more Intervención Ambiental Temprana en una Localidad .ronteriza de la Araucanía (S. XVI-XIX) RESUMEN Mediante crónicas españolas y documentación de época se reconstituye la evolución del uso del suelo, el desarrollo de las actividades agropecuarias y la temprana intervención ambiental en una localidad fronteriza de La Araucanía (San Pedro, Chile central). Se reconoce el progresivo aumento en la presión de uso debido a la consolidación del poblamiento hispano-criollo del área: i) alteración del sistema productivo indígena; ii) instalación del .uerte de San Pedro; iii) explotación de los recursos naturales iv) actividades agro-ganaderas sustentadas en especies biológicas introducidas; v) instalación de las haciendas de Lagunillas y Palco. El enclave militar y las haciendas se reconocen como polos radiales de intervención ambiental temprana y promotores de cambio de uso del suelo.
This work estimates the loss and fragmentation of native forest in the watershed of the river Ays... more This work estimates the loss and fragmentation of native forest in the watershed of the river Aysén during the 20th century, as a result of clearance fires induced by land settlers. In order to generate the reconstruction of the native forest cover, several documentary records and GIS ArcView 3.2 were used. Different indexes of landscape changes were applied (area, density and size of the fragment, core area, euclidean distance, shape and aggregation index, and edge length) to estimate the distribution of the native forest between 1900 and 1998, which indicate that the main replacement of the forest was by prairies. A loss of approximately 23% of native forest was registered, also an increase in the number of forest fragments (<100 ha), as a result of the settlement process. Howerer, the increasing number of fragments has a high connectivity, wich was corroborated using different landscape indexes.
RESUMEN ki crctividud turística puede representar un recurso no explotado; sin embargo es preciso... more RESUMEN ki crctividud turística puede representar un recurso no explotado; sin embargo es preciso planificar el espacio por medio de ttrétodos que pernritan la identifícación, localización y evaluación de todos los atractivos e infraestructura que formen parte del patrimonio turístico de una determinada zona. Es así que en la búsqueda de metodologías que puedan ser utilizadas en nuestro país se
PloS one, 2014
Metallurgical activities have been undertaken in northern South America (NSA) for millennia. Howe... more Metallurgical activities have been undertaken in northern South America (NSA) for millennia. However, it is still unknown how far atmospheric emissions from these activities have been transported. Since the timing of metallurgical activities is currently estimated from scarce archaeological discoveries, the availability of reliable and continuous records to refine the timing of past metal deposition in South America is essential, as it provides an alternative to discontinuous archives, as well as evidence for global trace metal transport. We show in a peat record from Tierra del Fuego that anthropogenic metals likely have been emitted into the atmosphere and transported from NSA to southern South America (SSA) over the last 4200 yrs. These findings are supported by modern time back-trajectories from NSA to SSA. We further show that apparent anthropogenic Cu and Sb emissions predate any archaeological evidence for metallurgical activities. Lead and Sn were also emitted into the atmos...
Revista chilena de historia natural, 2004
Revista Chilena De Historia Natural, 2002
Las características biogeográficas de la América templada favorecieron la introducción y propagac... more Las características biogeográficas de la América templada favorecieron la introducción y propagación de especies animales y vegetales que sustentaron al modelo agroganadero hispano-mediterráneo. Los efectos de este fenómeno generaron alteraciones ecológicas, especialmente en los territorios habitados por aborígenes carentes de actividades productivas intensivas, como fue el caso de la Araucanía. Mediante un análisis histórico documental, la presente investigación reconoció las principales características del proceso de alteración del paisaje ecológico araucano entre los siglos XVI y XVII: (i) en el siglo XVI, la introducción de especies exóticas desarticuló el sistema económico mapuche, (ii) tanto la relativa pristinidad de la Araucanía como el proceso bélico de los siglos XVI y XVII, favorecieron la introducción y propagación de las nuevas especies, (iii) durante el siglo XVI coexistieron especies nativas e introducidas, sin embargo, durante el siglo XVII preponderaron las exóticas, y (iv) este predominio habría generado la extinción local de especies animales y vegetales nativas, alterando definitivamente el paisaje ecológico araucano.
Journal of South American Earth Sciences, 2012
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Hydrobiologia, 2010
A sediment core encompassing the last 2000 years was extracted from Lake Laja, Chile, (36°54 0 S,... more A sediment core encompassing the last 2000 years was extracted from Lake Laja, Chile, (36°54 0 S, 71°05 0 W) using an Uwitec drilling platform. The sediment was subsampled for loss on ignition, nutrients, biogenic silica, and biological proxies (diatoms, chironomids, pollen). The sedimentary profile was characterized by several coarse volcanic layers. Loss on ignition, nutrients, and biogenic silica showed an increasing trend that suggests a recent shift to a higher trophic status.
Environmental Pollution, 2006
The lake sediment record of SCPs shows the record of fossil-fuel derived pollution in Central Chile.
The Southern Hemisphere has a crucial, but still not well constrained, role in global climatic fl... more The Southern Hemisphere has a crucial, but still not well constrained, role in global climatic fluctuations. In order to improve our understanding of the past climate changes in southern South America, we investigated the sedimentary record of three small lakes located between 45 and 48°S in Northern Chilean Patagonia. Our aim is to evaluate the occurrence of decennial-centennial scale climate
Climate of the Past, 2012
Glaciers are frequently used as indicators of climate change. However, the link between past glac... more Glaciers are frequently used as indicators of climate change. However, the link between past glacier fluctuations and climate variability is still highly debated. Here, we investigate the mid-to late-Holocene fluctuations of Gualas Glacier, one of the northernmost outlet glaciers of the Northern Patagonian Icefield, using a multi-proxy sedimentological and geochemical analysis of a 15 m long fjord sediment core from Golfo Elefantes, Chile, and historical documents from early Spanish explorers. Our results show that the core can be sub-divided into three main lithological units that were deposited under very different hydrodynamic conditions. Between 5400 and 4180 cal yr BP and after 750 cal yr BP, sedimentation in Golfo Elefantes was characterized by the rapid deposition of fine silt, most likely transported by fluvio-glacial processes. By contrast, the sediment deposited between 4130 and 850 cal yr BP is composed of poorly sorted sand that is free of shells. This interval is particularly marked by high magnetic susceptibility values and Zr concentrations, and likely reflects a major advance of Gualas glacier towards Golfo Elefantes during the Neoglaciation. Several thin silt layers observed in the upper part of the core are interpreted as secondary fluctuations of Gualas glacier during the Little Ice Age, in agreement with historical and dendrochronological data. Our interpretation of the Golfo Elefantes glaciomarine sediment record in terms of fluctuations of Gualas glacier is in excellent agreement with the glacier chronology proposed for the Southern Patagonian Icefield, which is based on terrestrial (moraine) deposits. By comparing our results with independent proxy records of precipitation and sea surface temperature, we suggest that the fluctuations of Gualas glacier during the last 5400 yr were mainly driven by changes in precipitation in the North Patagonian Andes.
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Papers by Fernando Torrejón