Jutta Lechterbeck

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° × 1° 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.

Is Neolithic land use correlated with demography? An evaluation of pollen-derived land cover and radiocarbon-inferred demographic change from Central Europe

The transformation of natural landscapes in Middle Europe began in the Neolithic as a result of the introduction of food-producing economies. This paper examines the relation between land-cover and demographic change in a regionally restricted case study. The study area is the Western Lake Constance area which has very detailed palynological as well as archaeological records. We compare land-cover change derived from nine pollen records using a pseudo-biomisation approach with 14C date probability density functions from archaeological sites which serve as a demographic proxy. We chose the Lake Constance area as a regional example where the pollen signal integrates a larger spatial pattern. The land-cover reconstructions for this region show first notable impacts at the Middle to Young Neolithic transition. The beginning of the Bronze Age is characterised by increases of arable land and pasture/meadow, whereas the deciduous woodland decreases dramatically. Changes in the land-cover classes show a correlation with the 14C density curve: the correlation is best with secondary woodland in the Young Neolithic which reflects the lake shore settlement dynamics. In the Early Bronze Age, the radiocarbon density correlates with open land-cover classes, such as pasture, meadow and arable land, reflecting a change in the land-use strategy. The close overall correspondence between the two archives implies that population dynamics and land-cover change were intrinsically linked. We therefore see human impact as a key driver for vegetation change in the Neolithic. Climate might have an influence on vegetation development, but the changes caused by human land use are clearly detectable from Neolithic times, at least in these densely settled, mid-altitude landscapes.

Botanical off-site and on-site data as indicators of different land use systems: a discussion with examples from Southwest Germany

Off-site pollen data as well as onsite plant macrofossil data from Southwest Germany enable the distinguishing of three main phases of agricultural land use history. The last phase, here simplified called the “Extensive ard phase”, had already started in the Bronze Age and ends in the 19th century a.d. It is characterized by extensive land management, permanent fields with short fallow phases, ploughing, the use of animal dung as fertilizer, and grazed woodlands. The first phase, comprising the Old and Middle Neolithic, is characterized by hoe-farming only on very fertile soils and a very restricted set of crops. For the second phase, comprising the Young, Late and Final Neolithic, a slash-and-burn-like agricultural system is most probable. During the Late and Final Neolithic, this cultivation system with fire use and shifting fields was gradually practised on permanent fields and was modified, leading finally to the “Extensive ard” land use system with fertilizer and ploughing instead of burning.

How was Bell Beaker economy related to Corded Ware and Early Bronze Age lifestyles? Archaeological, botanical and palynological evidence from the Hegau, Western Lake Constance region

Abstract The Europe wide spread of what has been called the Bell Beaker phenomenon remains an enigma of European prehistory. While most of the recent research stresses the ideological aspects of using Bell Beaker material culture, here we take a regional and economical perspective. We look for the chronological relationships and the economic choices of the Bell Beaker phase and of its closest neighbours in time and space: the Late Neolithic Corded Ware and the Early Bronze Age. We focus on the regional archaeological settlement history and present the hitherto richest European Bell Beaker-associated collection of palaeobotanical macro-remains, together with our high-resolution palynological work on annually laminated lake sediments. These different lines of evidence are tied together by an absolute chronology derived from new radiocarbon accelerated mass spectrometry (AMS) dates (now more than 200) and from the dendrodates from the World Heritage wet preserved pile dwellings. We show the preceding Late Neolithic, the actual Bell Beaker, and the following Early Bronze age economies each relying on different agricultural strategies that focus on distinct parts of the landscape. There is no link obvious between Late Neolithic and Bell Beaker, but there is between Bell Beaker and Early Bronze Age. Related to different modes of production, differences in ideology become visible in food preferences as well as in other parts of the material culture. We conclude that the Bell Beaker economy represents a re-orientation of the mode of production focusing on single, rather small farmsteads which often do not leave a distinct signal in the archaeological record.

A methodology for combined palynological and molecular geochemical high-resolution analysis of lake sediments

Abstract Continuous lake sediment records are increasingly important for a detailed reconstruction of Holocene paleoenvironmental and paleoclimatic conditions. Currently a variety of biotic, isotopic and biochemical proxies are routinely applied in multidisciplinary reconstructions, to compensate for deficits of individual analytical approaches. High-resolution records that can show evidence for environmental change on centennial or decadal scales require the analysis of small-sized samples of only a few grams or less, which often limits the application of multiple techniques on one discrete sample. Here, we describe a novel procedure for sequential analysis of molecular biomarkers and subsequent determination of pollen distribution on a single, small sediment sample. Lipids were efficiently recovered from freeze-dried sediment using organic solvent mixtures of dichloromethane in hexane (1:5, v/v) or a mixture of dichloromethane/methanol (l:l, v/v) via accelerated solvent extraction at 100°C and 75 bar pressure. Solvent extraction was shown to have no effect on pollen preservation, including surface microstructure study by scanning electron microscopy analysis, or pollen distribution. Sample amounts of 5.1, 3.6 and 1.1 g that were processed in triplicate gave identical results for pollen and molecular biomarker distribution. The analytical approach is applicable to high-resolution studies where very small amounts of only 1 g of sample material are available.