Holocene changes in forest composition in northern Patagonia responded to climate with little impact of disturbance

Postglacial climate change and changing disturbance regimes have shaped the vegetation composition in the forest-steppe ecotone in northern Patagonia (Argentina and Chile; lat. 40°‒lat. 43°S). Several investigations between 41° and 43°S document shifts in the position of the forest-steppe ecotone and the population expansion of the cypress Austrocedrus chilensis, while little is known about the vegetation dynamic of Nothofagus alpina and Nothofagus obliqua within the Lácar basin. With the aim to contribute to this respect, the sediments of a small lake within a dense Nothofagus forest, in the Lanín National Park were collected and analysed in high resolution for pollen charcoal and sediment composition. Additionally, this work assessed the role of natural disturbance on vegetation composition. Results document the environmental history for the last 11,600 years. The record indicates high fire activity during the early Holocene, associated with dry conditions and the presence of a diverse Nothofagus shrubland. The middle Holocene starts with increased percentage of Cupressaceae pollen (up to 15%) which drops following the dominance of Nothofagus associated with wet conditions and low fire frequency. The late Holocene is marked by the rise in the abundance of N. obliqua and N. alpina, documenting the spread and increased importance of these trees within the Lácar basin during the last two millennia. A statistically significant effect of ash deposition on overall vegetation composition could not be detected, while Hydrangea and Lomatia hirsuta seem to benefit from ash fall. Fire affected stands of A. chilensis and N. obliqua/N. alpina, but climate was likely the dominant factor controlling average vegetation composition. Recent anthropogenic disturbance is noticeable by the presence of introduced taxa Rumex, Plantago and Pinus, and by the decrease in the percentage of Nothofagus obliqua-type, associated to extensive timber activities around the Lácar basin

Late-Holocene vegetation dynamics and disturbance regimes in north Patagonia Argentina (40°S)

Natural disturbance processes such as volcanic eruptions, fire and human activities are important vegetation drivers in north Patagonia. Here, we tested the impact of volcanic ash fall and fire on vegetation composition analysing two sediment records, Lake Avutarda and Lake Bruja, located in the forest-steppe transition at 40°S. In addition, our analysis provides the first account on the history of Nothofagus alpina at its eastern distribution limits. Our results comprise the last 3000 years, indicating the persistence of the vegetation despite evident volcanic activity documented by numerous tephra layers in both records. Eleven fire episodes were identified, while redundancy analysis indicates a non-significant influence of fire activity on the vegetation. The population increase of Nothofagus alpina represents the most important change in vegetation composition in the last three millennia. We speculate that the presumed change in climate, which led to the expansion of Austrocedrus chilensis south of the study area, also caused the increase of Nothofagus alpina populations in the region

Holocene changes in forest composition in northern Patagonia responded to climate with little impact of disturbance

Here we present pollen and charcoal counts from a small lake located within the Lanín National Park, Argentina (40°12'S; 71°30'W; 1095 m a.s.l). The lacustrine sediment core was retrieved in January 2017. Pollen samples of 0.5 cm^3 were taken every 2 cm, avoiding tephra sections. Before and after major tephra layers the sampling was carried out at an interval of 1 cm. Processing of samples for pollen analysis was conducted following Bennett and Willis (2001; doi:10.1007/0-306-47668-1), including hydrofluoric acid and acetolysis. Samples with coarse particles were sieved at 120 µm. To reconstruct the past fire regime, macroscopic charcoal particles were counted in 1 cm^3 samples contiguously along the core at 1 cm intervals avoiding tephra layers wider than 1 cm. The samples were processed according to the methodology by Stevenson and Haberle (2005; hdl:1885/144170). Particles > 125 µm were counted under a binocular dissecting microscope (Whitlock and Anderson, 2003; doi:10.1007/0-387-21710-X_1)

Le tourisme basé sur la Science - Une approche Géographique

International audienceThis paper presents empirical research that supports territorial approaches to tourism product development that ground tourism in science, as a mechanism to support sustainable tourism heritage conservation goals. Scientific Tourism (ST), in this context, builds on the scientific heritage of a geography, matching researchers with local actors and tourists, through a five-stage iterative process that leads to new scientific knowledge, advancing theory and building relevance for communities through socio-cultural and economic development. This article focuses on the initial stage of the ST product development process, documenting empirical research conducted within the geographies surrounding the Palena River watershed in the Aysén Region of Chilean Patagonia. Both geo-structured literature review methods and results are presented and discussed to illustrate how the outcomes, including a series of maps, can inform and ground actors’ processes of heritage resource identification, justification, conservation, and exhibition, through the development of pilot ST initiatives within the territory. Similar research approaches may prove valuable for other low-density and peripheral geographies that share an interest in grounding tourism on the science taking place within their geography.Cet article présente une recherche empirique qui permet de renforcer une approche territorialisée du développement de produits touristiques. En ancrant le tourisme sur les connaissances scientifiques, cette démarche peut aider à la mise en valeur et conservation du patrimoine pour un tourisme durable. Le tourisme scientifique (TS) s'appuie sur le patrimoine scientifique d'une région géographique, en mettant en relation les chercheurs avec les acteurs locaux et les touristes. Par le biais d'un processus en cinq étapes qui débouche sur la création de nouvelles connaissances scientifiques, il permet de faire progresser les connaissances théoriques et renforce la pertinence des savoirs scientifiques pour les communautés locales et aide son développement socioculturel et économique. Cet article se concentre sur l'étape initiale du processus de développement de produits de TS en identifiant les recherches menées sur l'aire du bassin hydrographique de la rivière Palena, dans la région d'Aysén en Patagonie chilienne. Les résultats de l'analyse des publications scientifique sont géoréférencés et leur répartition spatiale analysée. Ce procédé illustre comment les données peuvent utilement informer les acteurs du territoire et aider à l'identification, la justification, la conservation et l'exposition de connaissances pouvant être intégrées dans la création d'initiatives pilotes de TS. Cette approche peut s'avérer précieuse pour d'autres territoires à faible densité, périphériques et naturels, qui partagent un intérêt à ancrer le développement du tourisme sur des connaissances scientifiques

Holocene changes in forest composition in northern Patagonia responded to climate with little impact of disturbance

Postglacial climate change and changing disturbance regimes have shaped the vegetation composition in the forest-steppe ecotone in northern Patagonia (Argentina and Chile; lat. 40°‒lat. 43°S). Several investigations between 41° and 43°S document shifts in the position of the forest-steppe ecotone and the population expansion of the cypress Austrocedrus chilensis, while little is known about the vegetation dynamic of Nothofagus alpina and Nothofagus obliqua within the Lácar basin. With the aim to contribute to this respect, the sediments of a small lake within a dense Nothofagus forest, in the Lanín National Park were collected and analysed in high resolution for pollen charcoal and sediment composition. Additionally, this work assessed the role of natural disturbance on vegetation composition. Results document the environmental history for the last 11,600 years. The record indicates high fire activity during the early Holocene, associated with dry conditions and the presence of a diverse Nothofagus shrubland. The middle Holocene starts with increased percentage of Cupressaceae pollen (up to 15%) which drops following the dominance of Nothofagus associated with wet conditions and low fire frequency. The late Holocene is marked by the rise in the abundance of N. obliqua and N. alpina, documenting the spread and increased importance of these trees within the Lácar basin during the last two millennia. A statistically significant effect of ash deposition on overall vegetation composition could not be detected, while Hydrangea and Lomatia hirsuta seem to benefit from ash fall. Fire affected stands of A. chilensis and N. obliqua/N. alpina, but climate was likely the dominant factor controlling average vegetation composition. Recent anthropogenic disturbance is noticeable by the presence of introduced taxa Rumex, Plantago and Pinus, and by the decrease in the percentage of Nothofagus obliqua-type, associated to extensive timber activities around the Lácar basin

Late-Holocene vegetation dynamics and disturbance regimes in north Patagonia Argentina (40°S)

Natural disturbance processes such as volcanic eruptions, fire and human activities are important vegetation drivers in north Patagonia. Here, we tested the impact of volcanic ash fall and fire on vegetation composition analysing two sediment records, Lake Avutarda and Lake Bruja, located in the forest-steppe transition at 40°S. In addition, our analysis provides the first account on the history of Nothofagus alpina at its eastern distribution limits. Our results comprise the last 3000 years, indicating the persistence of the vegetation despite evident volcanic activity documented by numerous tephra layers in both records. Eleven fire episodes were identified, while redundancy analysis indicates a non-significant influence of fire activity on the vegetation. The population increase of Nothofagus alpina represents the most important change in vegetation composition in the last three millennia. We speculate that the presumed change in climate, which led to the expansion of Austrocedrus chilensis south of the study area, also caused the increase of Nothofagus alpina populations in the region