- Email: [email protected]
Impact of Holocene climate changes on tree-line vegetation in the Wallis, Switzerland
Abstracts / Quaternary International 279-280 (2012) 9–120
atmospheric circulation occurred at c. 4000 and c. 2000 yrs ago (cal. BP). Climate change of this amplitude and duration is, although mild in a Quaternary perspective, severe enough to have affected humans and other large mammals in mountainous areas in the Arctic region. Despite this, the timing and effects of these significant and rapid changes have not received much attention. In this study we aim to characterise the mid-late Holocene climate in more detail using both a temperature proxy (chironomids) and a precipitation/glacier proxy (geochemical signatures obtained from XRF scanning) in sediments from lakes located above the tree-line in northern Sweden. In this ecologically sensitive setting changes in climate are expected to have caused quick responses in lake ecosystems. Based on stratigraphic data on chironomid community composition, July air temperatures are quantitatively reconstructed through a transfer function approach, using a modern Norwegian training set. The relative amount and frequency of precipitation is reconstructed based on changes in catchment erosion and deposition. Catchment erosion (including possible glacier influence) is characterised using X-ray density, XRF elemental data, grain size analysis, total organic carbon and geomorphology mapping. PALAEOBOTANICAL EVIDENCES OF PRE-COLUMBIAN AGRICULTURE IN BLACK SOILS (TERRA PRETA DO INDIO) IN WESTERN AMAZONIA Juan Carlos Berrio. University of Leicester, United Kingdom E-mail address: [email protected]
Palaeoecological research from different archaeological sites (Maicura, Omé and Takana) from the Colombian and Brazilian Amazon, show evidences of pre-Columbian agricultural activities in this region. Based on palaoebotanical (pollen, phytoliths and charcoal), geochemistry and radiocarbon analyses it was possible to determine different stages of development of Amazonian black soils. Radiocarbon control showed that Omé site was the oldest site (135040 yrs BP) followed by Takana (123040 yrs BP) and Maicura (105060 yrs BP). Palaoebotanical remains from the three studied sites showed corn (Zea mays), cassava (Manihot esculenta), hot-chilli peppers (Capsicum sp.), and palms such chontaduro/pupunha (Bactris gasipaes) as main cultivars in the pre-Columbian agricultural plots. Other important palm species like asaí (Euterpe precatoria) and canangucha/burití (Mauritia flexuosa), formed part of a varied used of native plant species (Solanum sp. Cariocar, Passiflora and Myrtacea) which complemented to the protein-rich diet based on fishery and hunting activities. Analysis of the fossil pollen shows similar flora composition of the surrounding vegetation, but no evidences of typical cultivars such as Zea mays. Notwithstanding, useful palms such as Euterpe and Mauritia were also recorded. At Takana site, preliminary results from pyrolysis (GC/MS) shows evidences of double alkanes at 1 cm, while at 34 and 50 cm show little evidence of alkanes, pointing to a strong reduction of the organic matter at deeper levels. This feature is also confirmed by the absence of preserved fossil pollen in the record. LANDSCAPE TRASNFORMATION AND CROP CULTIVATION IN TWO CONTRASTING ENVIRONMENTS IN COLOMBIA: EVIDENCES OF ANCIENT AGRICULTURAL RAISED FIELDS Juan Carlos Berrio. University of Leicester, United Kingdom E-mail address: [email protected]
A comparison of pollen records from two different archaeological sites located at different altitudes is presented. The San Marcos archaeological site lies at the Mompox Depression (74o33’45” W; 9o7’25” N, 150 m) in northern Colombia near the Caribbean coast. The Filomena archaeological site is located in the High Plain of Bogotá (73o45’30” W; 4o30’15” N, 2540 m) at 10 km distance, north of Bogotá city. Both archaeological sites display an evident extended landscape modification by pre-Columbians which includes the construction of particular raised fields suitable for crop cultivation since Middle Holocene. The San Marcos site comprises an extensive area ca. 700.000 ha whilst in the High Plain of Bogotá’s raised field covers ca. 200 ha. Based on aerial photographs, it was possible to recognise similar forms of raised fields, canals, causeways, reservoirs, dikes and mound settlements at both regions. The San Marcos pollen record spans back in time since 101010 AD and show a dominant gallery forest with slight variation towards open vegetation. During the last 250 yrs the
49
open vegetation became abundant due to cattle introduction and extensive pasture development in the region. The Filomena pollen diagram (180 BC) clearly shows variations in local swamp forest (Alnusddominated) and natural vegetation due to the strong human impact since pre-Columbian times. Both pollen diagrams share similar cultivation plant species like Capsicum and Zea mays. However, the San Marcos site presents other important taxa from lowland environment like Cucubita mixta, Ipomoea batatas, Manihot esculenta, Passiflora cf. nitida and Erythorxilum-type for the last 500 yrs. This last taxon it was probably lately introduce from the Sierra Nevada de Santa Marta as trade product. The Filomena site showed typical cultivar Andean taxa like Chenopodiaceae (possibly Quinua) Phaseolus, Solanum and Vicia faba. IMPACT OF HOLOCENE CLIMATE CHANGES ON TREE-LINE VEGETATION IN THE WALLIS, SWITZERLAND Nadine Berthel. Universität Bern, Switzerland E-mail address: [email protected]
Vegetation changes during the Holocene in relation to climate changes during that time can be reconstructed precisely using paleoecological methods. Knowledge about past reactions of vegetation to climate fluctuations may be of great value, especially with regard to anthropogenic climate change. In this context, tree-line vegetation is a convenient proxy, because even small changes in temperature may cause a distinct change in tree-line altitude and species composition. This study analyses a sediment core taken from a small lake, which is located at 2288 m a.s.l. in the Wallis, Switzerland. Furthermore, to gather comprehensive information about the processes, a multi-site approach including charcoal, spore and pollen analysis, as well as the analysis of plant macrofossils is applied. The study is still in progress. However, the absence of Abies pollen in the oldest layers of the core indicates a minimum age of about 8500 years BP. Additional absolute radiocarbon dating will soon give precise information. Moreover, the very low occurrence of plant macrofossils indicates that during these past 8500 years the lake was constantly located above tree line. EARLY PLEISTOCENE LANDSCAPES AND THE COLONIZATION OF EUROPE Adele Bertini. Dipartimento di Scienze della Terra- University of, Italy E-mail address: adele.bertini@unifi.it
The pace and causes of the early human colonization, in one or several migratory waves from Africa in new environments of the Eurasian continent during the Early Pleistocene, are still a matter of debate. However, climate change is considered a major driving factor of hominin evolution and dispersal patterns. In fact directly or indirectly by its severe influence on vegetation, physiography of landscape, and animal distribution, climate modulates the availability of resources. In this talk we intend to discuss some of the aspects, which we consider fundamental for the assessment of Early Pleistocene environments and their influence on early human colonization of Europe. On a local scale early human habitats can be characterised by defining the ecological requirements of early humans (ecospace) at sites of known hominin presence. Furthermore, the environments at possible human expansion routes have to be quantified by multiproxy-data on regional scales, supported by global climate and vegetation modelling of the phases of early human dispersal into Europe, in order to validate the overall consistency of local and regional proxy-data, and to asses climate systems at boundary conditions different from today. Based on the correlation of those data with new stratigraphic records and GIS techniques, the results will enable the generation of continental-scale as well as regional-specific environmental maps suitable for identifying the most likely corridors and scenarios having permitted human expansions and occupation at different times. We will present some examples from a palaeobotanical perspective of how such goals can be achieved in the future by marine and continental pollen data and their quantification. An earlier modelling effort to find areas of favourable vegetation and climate for Early Pleistocene hominins in Europe indicates that southern Spain, the extreme south tip of Italy and most of Turkey would have been favourable for their earliest dispersal.
atmospheric circulation occurred at c. 4000 and c. 2000 yrs ago (cal. BP). Climate change of this amplitude and duration is, although mild in a Quaternary perspective, severe enough to have affected humans and other large mammals in mountainous areas in the Arctic region. Despite this, the timing and effects of these significant and rapid changes have not received much attention. In this study we aim to characterise the mid-late Holocene climate in more detail using both a temperature proxy (chironomids) and a precipitation/glacier proxy (geochemical signatures obtained from XRF scanning) in sediments from lakes located above the tree-line in northern Sweden. In this ecologically sensitive setting changes in climate are expected to have caused quick responses in lake ecosystems. Based on stratigraphic data on chironomid community composition, July air temperatures are quantitatively reconstructed through a transfer function approach, using a modern Norwegian training set. The relative amount and frequency of precipitation is reconstructed based on changes in catchment erosion and deposition. Catchment erosion (including possible glacier influence) is characterised using X-ray density, XRF elemental data, grain size analysis, total organic carbon and geomorphology mapping. PALAEOBOTANICAL EVIDENCES OF PRE-COLUMBIAN AGRICULTURE IN BLACK SOILS (TERRA PRETA DO INDIO) IN WESTERN AMAZONIA Juan Carlos Berrio. University of Leicester, United Kingdom E-mail address: [email protected]
Palaeoecological research from different archaeological sites (Maicura, Omé and Takana) from the Colombian and Brazilian Amazon, show evidences of pre-Columbian agricultural activities in this region. Based on palaoebotanical (pollen, phytoliths and charcoal), geochemistry and radiocarbon analyses it was possible to determine different stages of development of Amazonian black soils. Radiocarbon control showed that Omé site was the oldest site (135040 yrs BP) followed by Takana (123040 yrs BP) and Maicura (105060 yrs BP). Palaoebotanical remains from the three studied sites showed corn (Zea mays), cassava (Manihot esculenta), hot-chilli peppers (Capsicum sp.), and palms such chontaduro/pupunha (Bactris gasipaes) as main cultivars in the pre-Columbian agricultural plots. Other important palm species like asaí (Euterpe precatoria) and canangucha/burití (Mauritia flexuosa), formed part of a varied used of native plant species (Solanum sp. Cariocar, Passiflora and Myrtacea) which complemented to the protein-rich diet based on fishery and hunting activities. Analysis of the fossil pollen shows similar flora composition of the surrounding vegetation, but no evidences of typical cultivars such as Zea mays. Notwithstanding, useful palms such as Euterpe and Mauritia were also recorded. At Takana site, preliminary results from pyrolysis (GC/MS) shows evidences of double alkanes at 1 cm, while at 34 and 50 cm show little evidence of alkanes, pointing to a strong reduction of the organic matter at deeper levels. This feature is also confirmed by the absence of preserved fossil pollen in the record. LANDSCAPE TRASNFORMATION AND CROP CULTIVATION IN TWO CONTRASTING ENVIRONMENTS IN COLOMBIA: EVIDENCES OF ANCIENT AGRICULTURAL RAISED FIELDS Juan Carlos Berrio. University of Leicester, United Kingdom E-mail address: [email protected]
A comparison of pollen records from two different archaeological sites located at different altitudes is presented. The San Marcos archaeological site lies at the Mompox Depression (74o33’45” W; 9o7’25” N, 150 m) in northern Colombia near the Caribbean coast. The Filomena archaeological site is located in the High Plain of Bogotá (73o45’30” W; 4o30’15” N, 2540 m) at 10 km distance, north of Bogotá city. Both archaeological sites display an evident extended landscape modification by pre-Columbians which includes the construction of particular raised fields suitable for crop cultivation since Middle Holocene. The San Marcos site comprises an extensive area ca. 700.000 ha whilst in the High Plain of Bogotá’s raised field covers ca. 200 ha. Based on aerial photographs, it was possible to recognise similar forms of raised fields, canals, causeways, reservoirs, dikes and mound settlements at both regions. The San Marcos pollen record spans back in time since 101010 AD and show a dominant gallery forest with slight variation towards open vegetation. During the last 250 yrs the
49
open vegetation became abundant due to cattle introduction and extensive pasture development in the region. The Filomena pollen diagram (180 BC) clearly shows variations in local swamp forest (Alnusddominated) and natural vegetation due to the strong human impact since pre-Columbian times. Both pollen diagrams share similar cultivation plant species like Capsicum and Zea mays. However, the San Marcos site presents other important taxa from lowland environment like Cucubita mixta, Ipomoea batatas, Manihot esculenta, Passiflora cf. nitida and Erythorxilum-type for the last 500 yrs. This last taxon it was probably lately introduce from the Sierra Nevada de Santa Marta as trade product. The Filomena site showed typical cultivar Andean taxa like Chenopodiaceae (possibly Quinua) Phaseolus, Solanum and Vicia faba. IMPACT OF HOLOCENE CLIMATE CHANGES ON TREE-LINE VEGETATION IN THE WALLIS, SWITZERLAND Nadine Berthel. Universität Bern, Switzerland E-mail address: [email protected]
Vegetation changes during the Holocene in relation to climate changes during that time can be reconstructed precisely using paleoecological methods. Knowledge about past reactions of vegetation to climate fluctuations may be of great value, especially with regard to anthropogenic climate change. In this context, tree-line vegetation is a convenient proxy, because even small changes in temperature may cause a distinct change in tree-line altitude and species composition. This study analyses a sediment core taken from a small lake, which is located at 2288 m a.s.l. in the Wallis, Switzerland. Furthermore, to gather comprehensive information about the processes, a multi-site approach including charcoal, spore and pollen analysis, as well as the analysis of plant macrofossils is applied. The study is still in progress. However, the absence of Abies pollen in the oldest layers of the core indicates a minimum age of about 8500 years BP. Additional absolute radiocarbon dating will soon give precise information. Moreover, the very low occurrence of plant macrofossils indicates that during these past 8500 years the lake was constantly located above tree line. EARLY PLEISTOCENE LANDSCAPES AND THE COLONIZATION OF EUROPE Adele Bertini. Dipartimento di Scienze della Terra- University of, Italy E-mail address: adele.bertini@unifi.it
The pace and causes of the early human colonization, in one or several migratory waves from Africa in new environments of the Eurasian continent during the Early Pleistocene, are still a matter of debate. However, climate change is considered a major driving factor of hominin evolution and dispersal patterns. In fact directly or indirectly by its severe influence on vegetation, physiography of landscape, and animal distribution, climate modulates the availability of resources. In this talk we intend to discuss some of the aspects, which we consider fundamental for the assessment of Early Pleistocene environments and their influence on early human colonization of Europe. On a local scale early human habitats can be characterised by defining the ecological requirements of early humans (ecospace) at sites of known hominin presence. Furthermore, the environments at possible human expansion routes have to be quantified by multiproxy-data on regional scales, supported by global climate and vegetation modelling of the phases of early human dispersal into Europe, in order to validate the overall consistency of local and regional proxy-data, and to asses climate systems at boundary conditions different from today. Based on the correlation of those data with new stratigraphic records and GIS techniques, the results will enable the generation of continental-scale as well as regional-specific environmental maps suitable for identifying the most likely corridors and scenarios having permitted human expansions and occupation at different times. We will present some examples from a palaeobotanical perspective of how such goals can be achieved in the future by marine and continental pollen data and their quantification. An earlier modelling effort to find areas of favourable vegetation and climate for Early Pleistocene hominins in Europe indicates that southern Spain, the extreme south tip of Italy and most of Turkey would have been favourable for their earliest dispersal.