Jean-François Berger

Land-use changes and environmental dynamics in the upper Rhone valley since Neolithic times inferred from sediments in Lac Moras

Lac Moras is a small lake located on a low-elevation plateau in the upper Rhône Valley (304 m a.s.l.). The upper 5 m of accumulated sediment in the lake span 7500 years and offer a detailed record of environmental perturbations and land-use history at a local scale. A multiproxy analysis (pollen, charcoal and geochemical parameters) led to the establishment of four periods of landscape dynamics. The first evidence of human impacts was recorded during the Neolithic and Bronze Age (6000–2700 cal. BP). These impacts were temporary and most likely affected small areas. The second period, in the Iron Age/classical antiquity (2200–1900 cal. BP), appears to be a key period in which the intensification of anthropogenic pressure (primarily grazing with localised areas of cultivation) caused high-intensity erosion events and deeply affected soil stability. During the Middle Ages, wheat, rye and hemp cultures as well as tree farming (walnut, chestnut) were intensively developed. From 50 cal. BP (the 19th century) onward, crop cultivation declined and was gradually replaced by meadows and pastures. According to these transformations in agro-pastoral practices, the associated use of fire changed. Whereas fire was used intensively to clear wild areas from the Neolithic to the early Middle Ages, its use was restricted to cleaning agro-pastoral areas during the second part of the Middle Ages. These periods correspond to the different reconstructed types of land use. These changes correspond to population growth, the evolution of settlement patterns and the increase in agrarian productivity by technological advances. The present landscape is a result of this coupled agrarian and environmental history. It is notable that the first permanent alteration occurred as early as classical antiquity.

Characterization and quantification of Holocene colluvial and alluvial sediments in the Valdaine Region (southern France)

This study presents a Holocene sediment budget for the Valdaine Region, located at the edge of the southern French Pre-Alps. Holocene colluvial and alluvial deposition are quantified based on existing and new field data. Average sediment thickness values were calculated for different landscape units, and available chronological data were used to make a time-differentiated sediment budget. Total Holocene colluvial deposition in the Valdaine (334 km2) amounts 167 × 106 m3, while alluvial deposition in the Roubion and Jabron catchments (in total 610 km2, including their catchment upstream the Valdaine) amounts 177 × 106 m3. Especially, colluvial deposition is high (0.75 × 106 g/m2) compared with other catchments. Three major deposition periods (8500–2000 bc, 700 bc–ad 800 and ad 1200–2000) and two periods of relative hillslope stability with local fluvial incision (2000–700 bc and ad 800–1200) set the framework for a time-differentiated sediment budget. Results show that depositional phases relate to intense land use and hillslope stability and fluvial incision to land abandonment. Catchment averaged colluvial deposition increases from 13 × 10−6 m3/m2/yr for 8500–2000 bc to 355 × 10−6 m3/m2/yr for ad 1200–2000, while alluvial deposition increases from 16 to 147 × 10−6 m3/m2/yr between the same time periods. A relationship with climatic fluctuations was not found because of the limited temporal resolution of the sediment budget. The derived sediment cascade model shows how alluvial sediments change from fine (silt and clay) to coarse (sand and gravel) after ad 1200. This went along with the establishment of a braided river pattern, indicating that the main source of sediment shifted to the mountainous headwaters. Further research including fingerprinting and modeling would be necessary to further understand the sediment budget and to more accurately quantify the different source areas and the export from the catchment.

Vegetation history of chernozems in the Czech Republic

Chernozem is a soil type which can be characterised by a thick dark surface horizon, which consists of organic matter and tends to change into a carbonate horizon or more often into a loess horizon. Chernozem is defined as a zonal soil that has developed under steppe vegetation in a dry continental climate. Nevertheless, chernozems can also be found in central Europe, where there are no climatic conditions for the existence of any steppe. This study is focused on the vegetational aspect of the pedogenesis of chernozems. We have examined three sorts of chernozems for their charcoal and pedological characteristics: the functional chernozems, the chernozems buried in Holocene material and the chernozems buried in Pleistocene material. The charcoal examination has proved the presence of woodland taxa in the areas of chernozems at different periods of time. The results of this study reveal that the high stability of soil organic matter has caused the persistence of chernozems in the areas with prevalent woodland vegetation.

Evolution and management of humid landscapes in northern Dauphiné (Rhone valley, France): Contribution of charcoal and wood studies

Using various archaeological and geoarchaeological operations, charcoal and waterlogged wood assemblages have been sampled in the marshy areas from the lower Dauphiné (Rhone valley, France). Their identification allows reconstructing the evolution of the woody vegetation in relation to climatohydrological changes and with human practices in the plain since the mid Holocene. It appears that humid-land forests have experienced a shift from ash formations (dominating during Pre- and Protohistory) toward alder formations between the Bronze Age and Roman Period. That vegetation change seems to be linked with pastoral practices in which fire is used as a clearing and regeneration tool. The intense pastoral use of the plain, together with the humidity of the soils when not artificially drained, may also have prevented the development of dense and mature forests. Finally, we show that beech, which is currently absent from the plain, probably grew in the marshlands during the past.

Introduction to the special issue: Roman canals studies—main research aims

This special issue of Water History is the first of a set of two volumes dedicated to canals and their evolution through time. These two publications derive from a workshop organised at the Maison de l’Orient et de la Mediterranee in Lyon (France) under the sponsorship of the University of Lyon 2 and the CNRS, on the 23rd and 24th of May 2012, entitled ‘‘Diverting water... Canals through time: a technological answer to socio-environmental variability’’. The themes of the workshop focused on ‘‘canals’’ and addressed the question of long-term interactions between nature and society, as well as the organisation and regulation of hydrologic and anthropic systems through time. This first volume focuses on a socio-cultural context: the ancient Roman world, i.e. an archetypical hydraulic society. The case studies developed are related to canals in environments characterized by complex interactions at different spatial and temporal scales (deltaic area, alluvial plain or mountains). They do not include urban water systems as the latter are too specific (water supply of the cities by aqueducts or the drain of waste water by sewers). The second volume will be structured around the issue of water management in

Canal through time: towards a multidisciplinary and holistic study of water systems?

This special issue of Water History is the second of a set of two volumes dedicated to thetheme: ‘‘Canal through time: a technological answer to socio-environmental variability?’’.These two publications derive from a workshop entitled «Diverting waters» which wasorganised on the 23rd and 24th of May 2012 at the Maison de l’Orient et de laMe´diterranne´e in Lyon, France. This workshop was sponsored by the CNRS, theUniversity Lyon 2 and its Social Science Doctoral School, as well as the ANR researchfunding organisation.The workshop addressed the question of the organisation and regulation of water sys-tems in space and time. In order to provide for their food, energetic/industrial and com-mercial needs, societies have devoted major financial and human means to water diversionand channelling. Among the hydraulic structures built by communities, canals, at theinterface between nature and culture, are a rich but still weakly-explored research object.