Holocene lake sediment core sequences from Lochnagar, Cairngorm Mts., Scotland - UK final report for CHILL-10,000

The CHILL 10,000 research objective at Lochnagar is to examine proxy data for temperature and climate conditions. Changes in lake sediment stratigraphical data can be used to reconstruct past conditions. These proxies include organic and minerogenic matter as a bulk proxy for catchment and within-lake productivity, chironomids as a proxy for air temperature, diatoms as an indicator for lake water pH, pollen as an indicator of catchment vegetation and finally biomarkers to help determine changes in proportions of organic source material within the lake mud

Temporal variations in English Populations of a forest insect pest, the green spruce aphid (Elatobium abietinum), associated with the North Atlantic Oscillation and global warming

Based on an exceptionally long modern ecological dataset (41 years), it has been possible to show that warm weather in England associated with a positive North Atlantic Oscillation (NAO) index causes the spring migration of the green spruce aphid (Elatobium abietinum), a pest species of spruce trees (Picea) to start earlier, continue for longer and contain more aphids. An upward trend in the NAO index during the period 1966-2006 is associated with an increasing population size of E. abietinum. It is important to understand the mechanisms behind the population fluctuations, because this aphid causes considerable damage to Picea plantations. Present day weather associated fluctuations in forest insect pests may be useful analogues in understanding past pest outbreaks in forests

People and climate: holocene sediment records of environmental change in Middle Egypt: fieldwork report and initial results

The aim of this project is to reveal more about the history of Lake Qarun through a multidisciplinary environmental study. This approach primarily concerns the examination of sediment records, but also includes collection of data from archaeological sites in the Faiyum. The sedimentary history of Lake Qarun will be compared with (i) independent palaeoclimate records for the East African Highlands and the eastern Mediterranean; (ii) local evidence (including Nile alluvial and palaeo-shoreline sequences and Holocene playa deposits); and (iii) the cultural history of the Faiyum. This report describes the fieldwork performed to obtain long sediment cores for palaeolimnological analysis and presents initial results from those cores. Results will be used to construct a Geographical Information System (GIS)

Pollen-based quantitative reconstructions of Holocene regional vegetation cover (plant-functional types and land-cover types) in Europe suitable for climate modelling

We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (bp)] at a 1 degrees x1 degrees spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources.Peer reviewe

Holocene land-cover reconstructions for studies on land cover-climate feedbacks

Peer reviewe

A multi-proxy study of lake-development in response to catchment changes during the Holocene at Lochnagar, north-east Scotland

This paper describes a multi-core lake sediment study using pollen, diatoms, and chironomids, together with magnetics and sediment biogeochemistry, as biotic and abiotic proxies to infer lake development in response to environmental change during the Holocene at Lochnagar in the eastern Highlands of Scotland. Diatoms are used to infer pH, chironomids to infer temperature, with pollen and plant megafossils acting as an independent proxy to validate these records and to provide insights into changes in catchment vegetation and soils. Lipid biomarkers are explored for their potential to provide additional information on lake productivity. The results indicate highly distinctive fluctuations in the loss-on-ignition (LOI) record, which are in phase with changes in some biotic (chironomid head-capsule concentration) and abiotic (coarse silt particle size fraction, and lipid and chlorine fractions) variables. Catchment-driven changes due to the development and degredation of soils, and the natural succession and human intervention on terrestrial catchment vegetation have the strongest influence on the diatom and chironomid assemblages. These catchment processes resulted in the natural acidification of the lake water. Post-industrial acidification of the lake was also influential on the lake biota. Climate-driven temperature change appears to have had only a weak influence on the biota with declines in cold stenothermic chironomid taxa in response to Early Holocene warming and declines in thermophilic chironomids in response to cooling at about 2600 cal. yr BP. © 2005 Published by Elsevier B.V