Interacción entre clima y ocupación humana en la configuración del paisaje vegetal del Parque Nacional de Aigüestortes i Estany de Sant Maurici a lo largo de los últimos 15.000 años

The vegetation of the National Park of Aigüestortes i Estany de St Maurici is the result of an interaction between climate, plant community dynamics and the human occupation of the territory. The OCUPAproject aimed to reconstruct this interaction across the last millennia combining methods from palaeoecology and archaeology. The study focused primarily on the Sant Nicolau valley and built on the multidisciplinary analysis of the sedimentary archive of two lakes (Llebreta and Redó) and a number of archaeological sites located in shelters and outdoors. There is archaeological evidence of human presencesince 9000 yr cal BP, and a continuous record since 7500 yr cal BP. At early stages, humans transformed the surroundings of the shelters occupied and lithic tools indicate contacts with locations far away (i.e.,the Ebro plains). Since more than 3000 years ago, there has been human impact on the vegetation withoutinterruption until present. Initially, the impacts were mostly related to livestock: use of fire to open grazing lands, soil erosion and, during the medieval period, forestry and eutrophication of lakes. The agriculture impact in the lower part of the valley (e.g., Llebreta) occurred about 2100 yr ago, although some cereal grains and tools for harvesting have been found for the Neolithic. In the medieval period, the impact was higher than during the last centuries. In general, the changes in the human land use approximately follow the major changes in climate, but the specific causal link is likely related to the social and cultural dynamics of a broader territory since the Neolithic

The impact of mining and hydropower in alpine lakes: The sedimentary record of Lake La Cueva (Asturias, NW Spain)

Past Global Changes. Open Science Meeting (5º. 2017. Zaragoza)La Cueva is a 21 m deep lake of glacial origin located at 1550 m.a.s.l in the western area of the Cantabrian Range (Asturias, NW Spain). Iron ore within the carbonatic bedrock outcropping in the catchment has been mined since the early 19th century until 1978. The area was recently subjected to an environmental restoration (2006) involving the re-deposition of large tailings in the lake watershed. Additionally, the construction of a hydropower plant downstream (1917), motivated the damming and hydraulic connection of La Cueva with this plant and two other lakes located upstream, leading to seasonal, human-controlled water level oscillations (<5 m). The multidisciplinary analysis of a 66 cm-long sediment core (sedimentology, geochemistry and diatoms), dated by 210Pb and radiocarbon, allows reconstructing the evolution of this lake from its natural, pristine status in the 12th century AD to the present. The oldest, recovered sediments (12th-19th centuries) are banded, siliciclastic silts and detrital carbonates, with predominantly benthic diatoms. The drastic change in sedimentation at the 19th century, marked by the deposition of reddish, massive hematite-rich silts and planktonic diatom species represents the input of mining wastes and the effects of major oscillations on the lake water level. An increase in sedimentation rates (from 0.5 to ca. 1.4 mm/year) was recorded during the mid-20th century, coinciding with the start of underground mining. A higher concentration of hematite and sedimentation rates (ca. 7 mm/yr) characterize the 21st century, after the end of mining activities and restoration. Smaller planktonic diatom species during this period might indicate lower nutrient availability and/or a more stable water column. The sedimentary record of La Cueva illustrates the complex interaction of climate variability and human impact in the recent evolution of alpine lakes and the importance of paleolimnological research on the evaluation of restoration measurements in natural protected areas.Instituto Geológico y Minero de España, EspañaUniversidad Complutense de Madrid, EspañaConsejo Superior de Investigaciones Científicas, EspañaCentre de Recerca Ecològica i Aplicacions Forestals, Universitat de Barcelona, EspañaPeer reviewe

Interacció entre clima i ocupació humana en la configuració del paisatge vegetal del Parc Nacional d'Aigüestortes i Estany de Sant Maurici

[EN] The vegetation of the National Park of Aigüestortes and Lake of Sant Maurici is the result of an interaction process between climate, plant community dynamics and the human occupation of the territory. The OCUPA project aims to reconstruct this interaction ovar the last millennia using methods of palaeoecolagy and archaeology. Here, we describe the main features of the project and summarize the results obtained so far. The study focuses primarily on the Sant Nicolau valley and bases on the multidisciplinary analysis of the sedimentary archive of two lakes (LLebreta and Redó) and a number of archaeological sites located in shelters and outdoors. There is archaaological evidence of human presence since 9.000 yr cal BP. and a continuous record since 7.500 yr cal BP. At early stages, they transformad the surroundings of the shelters occupied and lithic tools indicate contacts with areas as lar as the Ebro plains. Since the Bronze Age (ca. 4,300 yr cal BP) there has been human impact on the vegetation without interruption until present. Initialty, the impacts were mostly related to livestock: use of fire to open grassing areas, soil erosion and, during the medieval period, forestry and water eutrophication of lakes. The agricultura impact in lhe lower part of the valley (e.g., Llebreta) occurred about 2,100 yr ago, although some cereal grains and tools for harvesting have been found from the Neolithic. In the medieval period, the impact was much higher than during the last centurias. In general, it can be concluded that changes in the human land use approximately follow the major changes in climate, but the specific causal link is likely to be related to the social and cultural dynamics of a broader territory since the Neoliihic.[CA] El paísatge vegetal del Parc Nacional d'Aigüestortes i Estany do Sant Mauríci és el resultat d'un procés d'interacció entre el clima, els components de la mateixa vegetació i l'ocupació humana del territori. El projecte OCUPA té per objectiu reconstruir aquesta interacció al llarg deis darrers mil·lennis fent ús de métodes de la paleoecologia i l'arqueologia. Presentem aquí les característiques del projecte i fem un resum dels principals resultats obtinguts fins ara. L'estudi se centra sobretot en la vall de Sant Nicolau i es basa en l'análisi multidisciplinària del registre sedimentari de dos estanys (Llebreta i Rodó) i d'un bon nombre de jaciments arqueològics situats tant en abrics i balmes com a l'aire lliure. Hi ha evidències arqueològiques de presència humana des de 9.000 anys cal BP, i més continuadament des de 7.000 anys cal BP. Hi ha indicis que aquesta presència modifica l'entorn deis abrics, i de l'estudi de les eines lítiques es poden deduir contactes habituals amb zones tan allunyades com les planes de l'Ebre. Des de l'edat del bronze (ca. 4.300 anys cal BP) hi ha ocupació i impacte sobre el paisatge sense interrupció fins a l'actualitat. La influéncia va lligada sobrotot a lo ramaderia: utilització del foc per obrir espais de pastura; erosió del sòl, i, en periode medieval, explotació forestal i eutrofització de l'aigua dels estanys. L'impacte en el paisatge de l'agrlcultura de fons de vall (p. e., Llebreta) es produeix des de fa uns 2.100 anvs. encara que en els jaciments arqueològics es troben alguns grans de cereals i eines per segar tiges seques des del neolític. Durant el periode medieval l'impacte és molt superior al dels darrers segles i l'actualitat. En general, es pot concloure que el canvis en la forma de l'ocupació coincideixen a grans trets amb els principals canvis en el clima, però el lligam causal precís és probable que, ja des del neolític, estigui relacional amb la dinàmica cultural i social d'un territorl força més ampli, que també es veu condicionada pel clima.Peer reviewe

An ecological analysis of the high-mountain landscape acculturation since the neolithic: Mountain national parks as a model

[EN] The initial presence of humans in the high mountains almost since 8000 years ago shows more elements of domestication than initially estimated. Although the geographic extent of archaeological explorations is still limited, there is evidence of domestic livestock use and, in some cases, likely mixed-cereal agriculture at intermediate altitudes. It has not been possible to verify an impact of this activity on the landscape yet. In the Pyrenees, the distribution of archaeological sites in the high mountain changes associated with climate in the middle of the Holocene. The occupation of shelters and the number of archaeological sites decline. However, the human impact on the landscape is evident in some palaeoecological registers during the Bronze Age and involves the forest opening for grazing, probably using fire, on many occasions. The Middle Ages constitute the definitive transformation of the landscape and an organization of the use of the territory that has remained largely to present. A greater variety of land use, such as mining and metallurgy, added to livestock also with strong impact on forests. In the Sierra Nevada, the development of the irrigation ditch system by the Andalusians modified the hydrology to the present, with other implications on the landscape yet to be determined. Likely, the medieval imprint is still present in the current distribution of the species and the edaphic processes that occur in the high mountain. From the initial mosaic of incipient transformations to the forcefulness and diversity of the Middle Ages, the spatial projection and temporal continuity on how the landscape acculturation of the high-mountain took place still require a deeper exploration throughout the territory.[ES] La presencia inicial de los humanos en la alta montaña desde hace poco menos de 8000 años presenta más elementos de domesticación de lo que inicialmente se había estimado. Aunque la extensión geográfica de las exploraciones arqueológicas es todavía limitada, hay evidencias de uso de ganado doméstico y, en algunos casos, una probable agricultura utilizando mezcla de cereales a cotas intermedias. Por el momento, no se ha podido constatar impacto en el paisaje de esta actividad. En los Pirineos, hay una variación en la distribución de yacimientos ar-queológicos en la alta montaña asociada con el cambio climático de mitad del Holoceno. Decrece la ocupación de abrigos y el número de yacimientos en su conjunto. Sin embargo, el impacto humano sobre el paisaje es evidente durante la Edad del Bronce y supone la apertura de espacios para el pastoreo, probablemente, en muchas ocasiones utilizando fuego. La Edad Media supone la transformación definitiva del paisaje y una organización del uso del territorio que se ha mantenido en buena medida hasta la actualidad. Al uso ganadero se añade una mayor variedad de explotaciones, como la minería y metalurgia, que inciden también en una fuerte presión sobre los bos-ques. En Sierra Nevada, el desarrollo del sistema de acequias por los andalusíes condiciona la hidrología hasta la actualidad, seguramente con otras implicaciones sobre el paisaje todavía por especificar. Es probable que la huella medieval esté todavía presente en la distribución actual de las especies y en los procesos edáficos que se dan en la alta montaña. La proyección espacial y continuidad temporal sobre cómo se dio la culturización del paisaje de la alta montaña, desde el mosaico inicial de incipientes transformaciones hasta la contundencia y diversidad de la Edad Media, todavía requiere de una exploración más profunda a lo largo del territorio.Peer reviewe