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The modern floristic composition of the principal raised bogs of Wales is significantly altered compared with their histories of development from the early to mid Holocene. This paper uses pollen and plant macrofossil records from two raised bogs together with previously published data from a further two sites to explore the key factors contributing to the present condition of Welsh ombrotrophic plant communities. Results show Betula and Molinia invasion is a recent feature of bog development in Wales. Previous Holocene ‘dry-phases’ were characterized by Ericaceae and Pinus establishment, supporting recent experimental evidence that Betula and Molinia encroachment is primarily a response to nitrogen (N) loading rather than desiccation on intact bogs. Several of the bogs featured in this study also show severe signs of structural damage, not only from peat cutting but, in the case of Cors Caron, from channel processes in the adjacent River Teifi. Radiocarbon dating and inter-site comparisons of peat accumulation rates show that Rhos Goch Common in particular has been heavily impacted by peripheral peat cutting, leading to dewatering, significant subsidence of its peat dome and the spread of hummock and high dry ridge communities. Finally, the decline and local extinction of Sphagnum austinii in bogs across Europe represents one of the most significant changes in ombrotrophic community composition in the late Holocene. Co-registered pollen and macrofossil evidence from Cors Caron demonstrates that increases in landuse intensity over the last 2000 years are temporally associated with reductions in the abundance of S. austinii and ultimately its local disappearance from the palaeoecological record. [ABSTRACT FROM AUTHOR]

This paper presents a multiproxy high-resolution study of the past 2600 years for Seebergsee, a small Swiss lake with varved sediments at the present tree-line ecotone. The laminae were identified as varves by a numerical analysis of diatom counts in the thin-sections. The hypothesis of two diatom blooms per year was corroborated by the [sup 210]Pb and [sup 137]Cs chronology. A period of intensive pasturing during the 'Little Ice Age' between AD 1346 and AD 1595 is suggested by coprophilous fungal spores, as well as by pollen indicators of grazing, by the diatom-inferred total phosphorus, by geochemistry and by documentary data. The subsequent re-oligotrophication of the lake took about 88 years, as determined by the timelag between the decline of coprophile fungal spores and the restoration of pre-eutrophic nutrient conditions. According to previous studies of latewood densities from the same region, cold summers around AD 1600 limited the pasturing at this altitude. This demonstrated the socio-economic impact of a single climatic event. However, the variance partitioning between the effects of land use and climate, which was applied for the whole core, revealed that climate independent of land use and time explained only 1.32% of the diatom data, while land use independent of climate and time explained 15.7%. Clearly land use influenced the lake, but land use was not always driven by climate. Other factors beside climate, such as politics or the introduction of fertilizers in the seventeenth and eighteenth centuries also influenced the development of Alpine pasturing. [ABSTRACT FROM AUTHOR]

The late Holocene environmental history of two karstic uplands in the Burren, western Ireland is reconstructed. The palaeoecological investigations focus on species-rich, upland plant communities of high biogeographic interest that include Sesleria-dominated grasslands and heath communities with Dryas octopetala, Arctostaphylos uva-ursi and Empetrum nigrum. Short monoliths taken from shallow peats were pollen analytically investigated. Particular attention was paid to non-pollen palynomorphs, and especially coprophilous fungal spores as indicators of environmental change and pastoral activity at local level. The exposed north-west Burren uplands carried Pinus sylvestris-dominated woodland during the mid and late Bronze Age. The demise of pine on these uplands at ca. 600 B.C. is ascribed to human impact. Evidence is presented for increased pastoral activity in the uplands from early medieval times (ca. sixth century A.D.) onwards. Farming, involving intensive grazing of the uplands, attained greatest intensity during the late 18th and early 19th century, and resulted in more or less total clearance of Corylus scrub which, prior to that, was common in both the upland and lowland Burren. The potential of non-pollen palynomorphs and especially the coprophilous fungal spore record for elucidating traditional Burren farming practices, including winterage (a type of transhumance), is highlighted. [ABSTRACT FROM AUTHOR]

Apeat profile from a small raised bog, situated in SW Sweden, was studied for insect, pollen and charcoal analyses in order to reconstruct the late-Holocene forest history of the area. The palaeoecological records cover the last 3700 cal. years. The results were compared with archaeological data, historical documents and palaeoclimate reconstructions from the region. From 1650 cal. yr BC to AD 1310 cal. yr, the study area was characterized by deciduous woodland with a diverse invertebrate fauna. The recorded insects indicate a relatively open or mosaic forest environment with abundance of dead wood. This forest environment was probably maintained by disturbances such as cattle grazing, fire, wood coppicing and small-scale cultivation. At around AD 1310, a major and rapid change in the forest ecosystem occurred, ie, species-rich deciduous woodland was replaced by a species-poor beech forest. The data indicate that a change in land use was the likely reason for the shift in forest type. Grazing and fire ceased, while tree cutting increased. The shift in land use correlates well with political-societal changes in the region during Mediaeval time. Climate changes seem to have influenced the wetland environment, but there is no obvious correlation between major or minor shifts in forest ecosystem and reconstructed climate changes. Today, nature conservationists regard the beech forests of Halland as remains of primeval forests hosting a unique flora and fauna. Our results give new insights and challenge that view. [ABSTRACT FROM AUTHOR]

The decline of S. austinii Sull. Ex Aust. (formerly S. imbricatum Hornsch. Ex Russ. ssp. austinii Sull. Ex Aust.), in most cases to local extinction, represents one of the most striking vegetation changes on the raised bogs of Britain and Northwest Europe during the last 2000 years. This study uses plant macrofossil, pollen and geochemical analyses to explore the record of human impact and land-use intensification at the S. austinii decline. There is a clear temporal association between anthropogenic woodland clearance, cereal cultivation, soil erosion and contemporary climatic change, with the decline of S. austinii. These findings suggest that S. austinii is sensitive not only to rapid climate changes but also to the aerial deposition of soil dust and/or accompanying pollutants. A modern comparison of atmospherically derived nitrogen (N) loadings with the present presence/absence of S. austinii on 16 raised bogs shows that the species is only present where the loading lies below a critical threshold for N of 10 kg/ha per yr. The palaeoecological record also shows that S. austinii has re-established itself during phases of reduced human activity but in contemporary Europe it is difficult to see this happening in the near future. [ABSTRACT FROM AUTHOR]

For the first time, a high-resolution pollen/Coleoptera joint analysis is performed on a late Holocene sedimentary sequence located in the Lower Rhône Valley. 14 C dates validated by pollen data show that the bottom of the sequence is contemporaneous with the Greco-Roman period whereas the top is attributed to the present. This sequence yielded very rich pollen and insect assemblages, enabling a detailed reconstruction of the palaeoenvironment succession during the two last millennia around the site itself and more widely in the Arles plain. The very low pollen representation of trees and the near absence of tree-dependent Coleoptera suggest a marked deforestation of the area. The abundance of dung-beetles and nitrophytes is also in keeping with a strong grazing impact throughout the sequence. Three agricultural phases reflecting a growing level of human activities are identified. Phase 1 is contemporaneous with Celto-ligurian, Greek and Roman civilizations in Provence. At this time the forest cover was already largely destroyed, and pastoralism, cultivation of cereals, olives, vines and walnuts, was practised. Phase 2 is contemporaneous with a period spanning the Merovingian time and the Upper Middle Ages. It is characterized by increased agro-pastoral activities, probably related to the establishment of a monastic community at the Montmajour Abbey and to the settlement of farmers on the nearby Castellet hill. The major characteristic of agricultural phase 3 is the very high pollen percentages of Dipsacus fullonum or teasel, which was formerly extensively cultivated for cloth teasing. This early cultivation of an industrial plant, dated at La Calade to the twelfth century, is recorded for the first time in Provence. It may be connected with craft industries performed by monks at Montmajour Abbey. The sedimentological data suggest a succession of two stability phases interrupted by three flood phases. This interpretation agrees both with insect data, the fluctuating abundances of which are certainly connected with the alternation of ground submersion and dry periods, and with pollen data, marked by the impact of the floods upon the marshy vegetation. However, no clear climatic signal is recorded. [ABSTRACT FROM AUTHOR]