Ce projet porte sur la reconstitution paléo-écologique d'un environnement forestier fossile retrouvé sur un plateau au sud-ouest de l'île Bylot. Il a comme objectifs 1) de préciser la chrono-stratigraphie du site; 2) d’établir une liste et une succession des différents taxons polliniques retrouvés dans les différentes unités stratigraphiques du site; 3) d’estimer leur âge et 4) d’en inférer des conditions climatiques (température et précipitations). Plusieurs coupes stratigraphiques ont été excavées puis échantillonnées afin de réaliser des analyses stratigraphiques, paléomagnétiques et polliniques. Un GPS différentiel fut également utilisé afin de caractériser à petite et grande échelle les unités stratigraphiques associées aux unités organiques fossiles. Les résultats des analyses granulométriques indiquent la séquence de dépôt suivante au sein d’une dépression dans la roche en place (schiste tertiaire) : 1) un diamicton glaciaire local ; 2) un sédiment limoneux d’origine glacio-lacustre ; 3) une unité organique tourbeuse; 4) une unité de type alluvial ; 5) un sédiment fluvio-glaciaire et 6) un diamicton glaciaire d’origine allochtone. Les analyses polliniques suggèrent une végétation similaire à celle présente près de la limite des arbres actuelle, environ 2000 km plus au sud. Les conditions climatiques plus humides et plus chaudes permettaient notamment la croissance du pin (Pinus type strobus et banksiana), de l’épinette (Picea cf. mariana), de l’aulne (type crispa et incana) et du mélèze (Larix, indifférencié). Enfin, les études paléomagnétiques et la présence d’espèces éteintes suggèrent un âge pour les dépôts organiques fossiles situé entre 2,14 et 2,15 Ma ou entre 2,581 et 3,040 Ma. / The project focuses on the paleo-ecological reconstitution of a fossil forest environment found on a plateau on the southwest part of Bylot Island, in the Canadian Arctic. The objectives were 1) to describe the chrono-stratigraphy of the site; 2) to establish a list and the succession of different pollen taxa found in organic and inorganic fossil units of the site; 3) to estimate their age and 4) to infer the past climatic conditions of the site. Several stratigraphic cuts were excavated and sampled for stratigraphic, paleomagnetic and pollen analyses. Also, a differential GPS was used to characterise the stratigraphic units associated with the organic fossil units at a small and large scale. Results of the granulometric analysis suggest the following deposition sequence starting from a depression in the bedrock (tertiary shale): 1) a glacial diamicton with local clasts; 2) a silty sediment of glacio-lacustrine origin; 3) an organic peat unit; 4) an alluvial type unit; 5) a fluvio-glacial sediment and 6) a glacial diamicton of allochtone origin. The pollen analyses suggest vegetation similar to that of the current tree-line limit, situated about 2000 km south of the site. The climatic conditions were warmer and more humid, allowing the local growth of pines (Pinus type strobus and banksiana), spruce (Picea cf. mariana), alder (Alnus type crispa and incana) and larch (Larix, undifferentiated). Paleomagnetic analyses and the presence of extinct species finally suggest an age for the organic fossil deposits of between 2,14 and 2,15 My or most likely between 2,581 and 3,040 My.

A two-year analysis of pollen rain was conducted in the Pretoria-Witwatersrand-Vereeniging district of the Transvaal, South Africa. Poaceae WaS the major component of the pollen assemblage, comprising 52% regionally. Of the total pollen count, 58.8% was non-seasonal and present throughout the year. During the analysis it became apparent that fungal spores dominated the atmospheric content, accounting for 94% of total airspora, considered here to incl ude pollen and fUngal spores.[Abbreviated Abstract. Open document to view full version]. / AC2017

Análises palinológicas desenvolvidas com depósitos do Estado do Rio Grande do Sul estiveram, em sua maioria, relacionadas ao estudo das jazidas de carvão da Formação Rio Bonito, que resultaram na identificação de associações palinológicas vinculadas a formação de paleoturfeiras. O consequente reconhecimento das demais associações palinológicas da passagem entre o Grupo Itararé e a Formação Rio Bonito é menos detalhado, necessitando-se aprimorar os limites da paleovegetação e das palinozonas estabelecidas. Esta dissertação compreende a análise palinológica de níveis do poço ST-01-RS, localizado na região de Cachoeira do Sul, centro do Rio Grande do Sul. Um total de 25 (vinte e cinco) amostras de subsuperfície foi coletado, envolvendo o intervalo entre o Grupo Itararé e a Formação Rio Bonito. A análise palinológica permitiu a identificação de 28 gêneros de palinomorfos, dentre os quais 08 (oito) são relativos a esporos triletes acavados, 04 (quatro) a esporos triletes cavados cingulizonados, 05 (cinco) relativos a grãos de pólen monossacados, 01 (um) a grão de pólen bissacado liso e 09 (nove) a grãos de pólen estriados e pré-colpados, enquanto 04 (quatro) formas são relacionadas a elementos constituintes do microplâncton (algas clorofíceas), 01 (um) gênero de esporo de fungo 01 (um) acritarco não determinado. As características quantitativas dos conjuntos palinológicos recuperados permitiram a proposição de 02 (duas) fases palinoflorísticas, designadas como Fase I, ocorrente entre as porções inferior e média do testemunho (Grupo Itararé) e Fase II, que abrange o topo do Grupo Itararé e a Formação Rio Bonito. As distribuições dos táxons nas duas unidades revelaram que a Fase I representa uma paleovegetação herbácea composta predominantemente de Pteridospermopsida (esporos) em um ambiente com condições climáticas úmidas; espécimes de Gimnospermopsida (grãos de pólen) são subordinados. Durante a Fase II, a vegetação caracteriza-se por alterações parciais do contexto da Fase I, ainda com Pteridospermopsida dominantes, porém com maior participação da vegetação arborescente (Gimnospermopsida) em paleoambiente de clima úmido nas áreas mais baixas relacionadas aos corpos d’água provavelmente circundado por áreas mais elevadas cobertas por representante de Gimnospermopsida. Em ambas as fases, algas e esporos de fungos são escassos. O Grupo Itararé e a Formação Rio Bonito apresentam 7 conjuntos palinológicos semelhantes, com variações nas proporções entre gêneros de uma unidade para a outra, bem como registrado em outros trabalhos realizados em depósitos do Rio Grande do Sul, o que demonstra a existência de discretas e locais variações paleoclimáticas e paleoambientais. / Palynological analysis developed with deposits in the State of Rio Grande do Sul were mostly related to the study of the coal deposits of the Rio Bonito Formation, which resulted in the identification of palynological associations related to paleo peat-forming. The consequent recognition of the other palinological associations of the passage between the Itararé Group and the Rio Bonito Formation is less detailed and it is necessary to improve the limits of the palaeovegetation and palinozones established. This dissertation comprises the palynological study of levels of well ST-01-RS, located in the region of Cachoeira do Sul, central Rio Grande do Sul state. A total of 25 (twenty-five) subsurface samples were collected, involving the interval between the Itararé Group and the Rio Bonito Formation. The palynological analysis allowed the identification of 29 (twenty-nine) genera of palynomorphs, of which 08 (eight) were related to trilete spores, 05 (five) related to monosacted pollen grains, 01 (one) the grain of laevigati pollen grains and 09 (nine) pollen grains are praecolpati, while 04 (four) forms are related to constituent elements of the microplankton (algae), 01 (one) genus of fungi spore and 01 (one) acritarch not determined. The quantitative characteristics of the recovered palynological assemblages allowed the proposition of 02 (two) palinofloristic phases, designated as Phase I, occurring between the lower and middle portions of the well (Itararé Group) and Phase II, which covers the top of the Itararé Group and Rio Bonito Formation. The distributions of the taxa in the two units revealed that Phase I presents an herbaceous paleovegegation composed predominantly of Pteridospermopsida (spores) in an environment with humid climatic conditions; specimens of Gimnospermopsida (pollen grains) are subordinate. During Phase II, vegetation is characterized by partial alterations of the Phase I context, still with dominant Pteridospermopsida, but with an increase of the arborescent vegetation (Gimnospermopsida) in a humid climate paleoenvironment in the lower areas related to probably circled water bodies by higher areas covered by representative of Gymnospermopsida. In both phases, algae and fungi spores are scarce. The Itararé Group and the Rio Bonito Formation have similar palynological assemblages, with variations in the proportions between genera from one unit to the other, as well as recorded in other studies carried out in Rio Grande do Sul deposits, which demonstrates the existence of discrete and localy paleoclimatic and paleoenvironmental changes.

Le Bergsee offre une séquence sédimentaire terrestre et continue sur l’histoire environnementale de l’Europe de l’Ouest entre 50 ka BP et aujourd’hui.Un enregistrement pollinique continu et séculaire permet la construction de l’évolution de la végétation et du climat sur la dernière période glaciaire.Outre l’opposition entre le Stade Isotopique Marin 3 et 2 (le second étant plus steppique), la succession de stades et d’interstades courts nord-atlantiques est reflétée par l’alternance de steppes (i.e. climat froid/sec) et de courts épisodes forestiers (i.e. réchauffements). Des phases glaciaires plus prononcées attestent de Stades de Heinrich en Europe de l’Ouest.Ces résultats sont validés par : 1) la confrontation avec des études européennes et 2) l’approche multi-proxy (chironomes, alkanes, géochimie) appliquée à des épisodes clés.Une comparaison avec les données archéologiques montre finalement le potentiel de contribution du contexte climato-environnemental du Bergsee à la compréhension des changements sociétaux du Paléolithique Supérieur. / Bergsee Lake provides a terrestrial and continuous sediment record of environmental changes in Western Europe for the last 50 ka.A continuous pollen record established at secular resolution allow to reconstruct the vegetation and climate variability of the Last Glacial period.Contrasted climate/vegetation is recorded between Marine Isotope Stages 3 and 2 (more steppic for the second one), and the north-Atlantic stadial/interstadial succession is also reflected by alternating steppe (i.e. cold/dry climate) and short forested episodes (i.e. warming). Moreover, Heinrich Stadials are evidenced as pronounced glacial phases by the Bergsee record.These results are supported by 1) comparison with other European records and 2) the multi-proxy approach (chironomids, alkanes, sedimentary data) applied on key climatic periods.Finally, comparison with archaeological data highlights the great potential contribution of the Bergsee record to the understanding of society changes of the Late Palaeolithic.

En esta tesis se presenta un estudio sobre la evolución de paisajes mediterráneos continentales a partir de varios registros polínicos procedentes de sectores meridionales de Guadalajara y del Llano Occidental Catalán. El término paisaje es entendido en este trabajo como el resultado de las interacciones entre sociedad humana y medio. Los cambios reflejados en el paisaje a partir del registro polínico ponen de manifiesto, por tanto, las prácticas humanas, la historia ambiental, los usos del suelo y la variabilidad climática. El uso de datos paleoambientales de dos sectores geográficos diferentes permite su intercomparación. Esta estrategia de investigación permite la identificación de tendencias comunes y divergencias, lo que permite determinar el papel humano en el cambio paisajístico a lo largo del tiempo. Tres registros polínicos fueron obtenidos en Guadalajara: Somolinos α (174 cm comprendiendo desde 1600 cal aC. hasta época actual), Somolinos PAS (380 cm cubriendo desde 800 cal aC hasta 700 cal dC) y Cañamares (250 cm depth cubriendo desde 450 cal aC hasta época actual). En el Llano Occidental Catalán se obtuvieron dos registros polínicos: Ivars (415 cm cubriendo desde 800 cal aC hasta 1500 cal dC) y Els Vilars d’Arbeca (yacimiento arqueológico con algunas muestras datadas en el s. IV cal aC). El análisis de los registros de Guadalajara ha permitido determinar que el Macizo de Pela estuvo forestado durante el I milenio aC. Este sector experimentó una transformación paisajística importante en el s. I cal aC, resultado de la administración romana del territorio y de la extensión de las actividades agropecuarias. Durante el período visigótico y andalusí (s. V a XI dC) las actividades antrópicas se desintensificaron, aunque el medio permaneció abierto. Posteriormente, durante la expansión cristiana, las actividades humanas y el bosque experimentaron un avance. Entre los s. XVI y XIX dC, el sector asiste a una extensión de los pastizales vinculados al desarrollo de una importante actividad transhumante. En el Llano Occidental Catalán los registros polínicos evidencian la existencia de un paisaje abierto y la presencia de vegetación adaptada a condiciones de semiaridez desde el s. IX cal aC. En este momento se constatan evidencias de actividades antrópicas, especialmente de ganadería. Episodios puntuales de aridez parecen incidir en el sector en torno a ca. 700 cal aC. No obstante, desde ca. 450 cal aC estos episodios podrían haberse acentuado, pudiendo haber ocasionado una desecación parcial de la laguna e impidiendo la conservación polínica. Este período seco pudo estar vinculado al abandono del asentamiento de Els Vilars d’Arbeca. No obstante, otros asentamientos ibéricos continuaron ocupados entre el s. V aC y el II aC, lo cual podría sugerir la existencia de diferentes estrategias adaptativas a la variabilidad ambiental por parte de estas comunidades de la Edad del Hierro. Las actividades antrópicas fueron escasas durante época romana bajoimperial. En este momento, el bosque experimentó un avance. No obstante, en s. V cal dC, durante el período visigótico, se detectan importantes deforestaciones. Bajo el desarrollo de la administración andalusí en el sector se constata la extensión de las actividades agrícolas. Posteriormente, el área se establece como una región fronteriza entre los condados cristianos septentrionales y los reinos musulmanes meridionales, ofreciendo escasas evidencias de explotación territorial. Posteriormente, el sector experimentó un desarrollo importante de la agricultura durante la Baja Edad Media. En este momento se constata, además, el desarrollo de la actividad ganadera, probablemente vinculada al desarrollo de rutas trashumantes establecidas entre las llanuras leridanas y las cordilleras montañosas septentrionales. Este trabajo ha permitido documentar diferentes respuestas al cambio ambiental en la Península Ibérica, vinculadas a los diferentes factores políticos, económicos y sociales que predominaron en los diferentes territorios. Por otra parte, los datos paleoambientales ponen de manifiesto la relevancia del papel humano en el cambio paisajístico de los sectores de media montaña peninsular durante época romana. / "Evolution of Mediterranean continental landscapes in Lleida and Guadalajara during the last 3000 years on the basis of Ivars, Somolinos and Cañamares pollen sequences." Abstract: The evolution of landscapes through time has been studied in this work by the analysis of several pollen records from two Mediterranean continental areas of the Iberian Peninsula: the Northern Guadalajara area and the Western Plain of Catalonia. Landscapes are understood in this work as a result of the relationship between human societies and the environment. Subsequently, the changes in landscape reported by pollen record reflect the evolution of the human practices, environmental history, land-use, climate variability. The use of palaenvironmental data from two areas enables a comparison between sites. !is approach has allowed to identify convergence/divergence trends and, in consequence, to assess the role of human agency in the evolution of landscape through time. Three pollen records were obtained in Guadalajara area: Somolinos α (174 cm depth covering from 1600 cal AD to present time), Somolinos PAS (380 cm depth covering from 9th century cal BC to 8th century cal AD) and Cañamares (250 cm depth covering from 5th century cal AD to present time). Two pollen records were obtained in the Western Plain of Catalonia: Ivars (415 cm depth covering from 9th cal century BC to 15th century cal AD) and Els Vilars d’Arbeca archaeological site, of which some sedimentary samples were dated at 4th century cal BC). The analysis of the Guadalajara records has allowed to clarify that the Pela Massif was formerly forested during the 1st millennium BC. !is sector experienced a major landscape transformation in the 1st century cal BC, as a result of the onset of Roman administration at Tiermes and the widespread of extensive farming and grazing through the land. During the Visigothic and Andalusian periods (5th to 11th century AD) human activities reduced, but the area still remained as an open landscape. Later on, after the expansion of the northern Christian kingdoms towards the South, both the forest and the human activities recovered in this area. Between the 16th and 19th centuries the area transformed into pastures linked to the development of transhumance activities. In the Western Plain of Catalonia the pollen records has evidenced an open landscape and the presence of semi-arid vegetation since 9th century cal BC. At this time, evidences of human activities, specially of grazing, are reported. Episodes of droughts seemed to be recurrent in ca. 700 cal BC, however, a major dry period started in ca. 450 cal BC and involved the interruption of the pollen preservation, resulting from a possible dissecation of the Ivars lake. !is dry period could be linked to the abandonment of Els Vilars archaeological site. However, other Iberian villages still remained occupied between 5th and 2nd century BC, which may suggest different adaptative strategies to environmental variability of these Iron Age societies. Human activities were reduced in late roman times, the period when the pollen record is resumed. At this point, the forest had recovered, however, major deforestations occurred during the Visigothic times in 5th century cal AD. With the development of Andalusian administration, a slight development of agriculture is witnessed. Later on, the area remained as a boundary between northern Christian and southern Muslim kingdoms, with no evidences of land exploitation. Nevertheless, in late medieval times the area experienced a major spread of farming and also grazing, which was probably linked to the establishment of transhumace routes between the Lleida Plains and the high mountain ranges in the North. This work has documented diverse responses to climate change in the Iberian Peninsula, which are linked to the different economic, social and political factors prevailing in several territories. At this respect, alaeoenvironmental data highlights the strong capacitiy to modify the landscape by Roman people in entral areas of Iberia.

No description available.

No description available.

The upper Bay of Fundy's Cumberland Basin contains an estimated 16,500 hectares of salt marsh, nearly all of which have been diked and converted to agricultural lands since the arrival of the Acadians in the late 17 th century. John Lusby Marsh is a 600 ha salt marsh that was diked and farmed for approximately 250 years, until dikes breached in the late 1940s and the marsh was restored to tidal conditions. A sediment core that contained the reclamation surface was extracted in John Lusby Marsh, and a trial set of eight fossil pollen spectra was compared to the modern analogues. Discriminant analysis classified the fossil samples into a plausible sequence of historic land uses which included phases when the marsh was diked and farmed. A comparison of the soil characteristics and pollen spectra from this study to those in a previously published study of a nearby salt marsh at Amherst N.S. suggest that flooding of a dikeland was misinterpreted as a sudden increase in the rate of sea level rise. Historical air photos support this conclusion by showing that the sampling location was indeed diked and farmed before the 1940s.

Ce projet porte sur la reconstitution paléo-écologique d'un environnement forestier fossile retrouvé sur un plateau au sud-ouest de l'île Bylot. Il a comme objectifs 1) de préciser la chrono-stratigraphie du site; 2) d’établir une liste et une succession des différents taxons polliniques retrouvés dans les différentes unités stratigraphiques du site; 3) d’estimer leur âge et 4) d’en inférer des conditions climatiques (température et précipitations). Plusieurs coupes stratigraphiques ont été excavées puis échantillonnées afin de réaliser des analyses stratigraphiques, paléomagnétiques et polliniques. Un GPS différentiel fut également utilisé afin de caractériser à petite et grande échelle les unités stratigraphiques associées aux unités organiques fossiles. Les résultats des analyses granulométriques indiquent la séquence de dépôt suivante au sein d’une dépression dans la roche en place (schiste tertiaire) : 1) un diamicton glaciaire local ; 2) un sédiment limoneux d’origine glacio-lacustre ; 3) une unité organique tourbeuse; 4) une unité de type alluvial ; 5) un sédiment fluvio-glaciaire et 6) un diamicton glaciaire d’origine allochtone. Les analyses polliniques suggèrent une végétation similaire à celle présente près de la limite des arbres actuelle, environ 2000 km plus au sud. Les conditions climatiques plus humides et plus chaudes permettaient notamment la croissance du pin (Pinus type strobus et banksiana), de l’épinette (Picea cf. mariana), de l’aulne (type crispa et incana) et du mélèze (Larix, indifférencié). Enfin, les études paléomagnétiques et la présence d’espèces éteintes suggèrent un âge pour les dépôts organiques fossiles situé entre 2,14 et 2,15 Ma ou entre 2,581 et 3,040 Ma. / The project focuses on the paleo-ecological reconstitution of a fossil forest environment found on a plateau on the southwest part of Bylot Island, in the Canadian Arctic. The objectives were 1) to describe the chrono-stratigraphy of the site; 2) to establish a list and the succession of different pollen taxa found in organic and inorganic fossil units of the site; 3) to estimate their age and 4) to infer the past climatic conditions of the site. Several stratigraphic cuts were excavated and sampled for stratigraphic, paleomagnetic and pollen analyses. Also, a differential GPS was used to characterise the stratigraphic units associated with the organic fossil units at a small and large scale. Results of the granulometric analysis suggest the following deposition sequence starting from a depression in the bedrock (tertiary shale): 1) a glacial diamicton with local clasts; 2) a silty sediment of glacio-lacustrine origin; 3) an organic peat unit; 4) an alluvial type unit; 5) a fluvio-glacial sediment and 6) a glacial diamicton of allochtone origin. The pollen analyses suggest vegetation similar to that of the current tree-line limit, situated about 2000 km south of the site. The climatic conditions were warmer and more humid, allowing the local growth of pines (Pinus type strobus and banksiana), spruce (Picea cf. mariana), alder (Alnus type crispa and incana) and larch (Larix, undifferentiated). Paleomagnetic analyses and the presence of extinct species finally suggest an age for the organic fossil deposits of between 2,14 and 2,15 My or most likely between 2,581 and 3,040 My.

Pollen records from southeastern Vancouver Island, British Columbia, show changes in vegetation and climate from the late Olympia Interstade through the Fraser Glaciation. This study provides important insights into phytogeographic patterns of Pacific Northwest flora, leads to an enhanced understanding of processes affecting present-day ranges of several plant taxa, and provides a historical perspective on the origin of coastal alpine ecosystems. Evidence for a previously unrecognized glacial advance in the region at ~21,000 14C yr BP, herein called the Saanich glacier, is provided. The results reveal widespread habitat and food sources suitable for the mega fauna that lived on southern Vancouver Island during the last glaciation. Vegetation during the Fraser Glaciation represented a mosaic of plant communities across a heterogeneous and productive landscape. Pollen spectra indicate that plant assemblages, dominated by Poaceae and Cyperaceae, were widespread. Similarities to tundra in northern Alaska and high elevation sites in British Columbia were detected. Vegetation varied geographically in the late Olympia (ca. 33,500-29,000 14C yr BP). Grassy uplands with scattered trees and local moist meadows occurred at Qualicum Beach under mesic and cool conditions, while cold and dry grass tundra prevailed at Skutz Falls. Increased non-arboreal pollen percentages at Qualicum Beach, 29,000 14C yr BP, reflect expansion of grassy meadows with diverse herbs under a cool and dry climate at the onset of the Fraser Glaciation. At Qualicum Beach between 25,160-24,190 14C yr BP, sedge wetlands were surrounded by open, dry uplands. Concurrently at Osborne Bay, Pinus-Picea-Abies-Poaceae parkland occurred. Dry and cold climate intensified as the Fraser Glaciation progressed after 24,000 14C yr BP and non-arboreal communities expanded. At Cordova Bay, cold and dry tundra or parkland in upland sites, and sedge wetlands on an aggrading floodplain are recorded. Sparse tree cover and grass-tundra surrounded a floodplain at Skutz Falls around 21,000 14C yr BP under cool and dry climate. Subalpine-like Picea-Abies-Pinus parkland and moist, species-rich grassland meadows occurred at McKenzie Bight at the same time. A sedge wetland occupied the site of deposition, and was periodically inundated as lake levels fluctuated. Upland grasslands at Cordova Bay are recorded between 21,600–19,400 14C yr BP, while local ponded areas developed on an aggrading floodplain at sea level. From 19,400-19,300 14C yr BP, parkland at Cordova Bay developed as climate moistened and warmed at the time of the Port Moody Interstade known from the Fraser Lowland. Abundant marine dinoflagellate cysts between 21,600–19,400 14C yr BP, reveal a high sea level stand and strong marine influence at Cordova Bay. Glacioisostatic depression of the crust on the east side of Vancouver Island is the most probable explanation. The presence of pollen-bearing glacio-lacustrine sediments at McKenzie Bight around 21,000 14C yr BP at ~93 m and contemporaneous isostatic crustal depression at Cordova Bay strongly suggest a major glacial body in the region at the same time as the Coquitlam advance in the Lower Mainland. Ice-free landscapes may have occurred on southern Vancouver Island through the Fraser glaciation beyond the Saanich glacier ice limits. / Graduate