Holocene paleoecological changes and agro-pastoral impact on the La Narce du Béage mire (Massif Central, France)

Abstract

A paleoecological study (macrofossils, pollen, cryptogam spores, non-pollen palynomorphs) was performed to investigate environmental changes recorded on the peat deposits of the La Narce du Béage mire (Massif Central, France). We reconstructed the development of a limnogenous mire ecosystem during the Holocene, consequently to the infilling of a small Late Glacial lake. Successions from aquatic flora ( Isoëtes, Nitella opaca/ syncarpa, Botryococcus, Alisma plantago-aquatica, Potamogeton, Sparganium) to mire plant species ( Alnus glutinosa, Betula nana, Betula pubescens, Cyperaceae, Ericaceae, Sphagnum) underlined a gradual eutrophication and acidification during the lowering of the water table. We demonstrated a clear link between these local hydro-ecological changes and the early Holocene climatic warming. Also dealing with archeology, we provided key issues for the identification of human-induced environmental changes. Three phases of ecological disturbances with clearings of the mixed-oak forest and agro-pastoral activities were evidenced at 7700–7300, 6800–6420, and 5500–4250 cal. BP. Our results confirmed early Neolithic (Cardial influences), middle Neolithic (Chassean), and late Neolithic (Ferrières group) frequentations of the Béage Plateau, probably included in large-scale socio-cultural changes (SE France, NW Mediterranean Basin). Later, forest clearings (beech and fir), cultivation, and pastoralism were outlined since the Iron Age (after 2300 cal. BP, that is, 350 BC). Increasing human pressure was especially recorded during the last 1700 years, with rye ( Secale cereale) cultivation and extensive livestock grazing around and on the mire, which is nowadays a protected ‘Natura 2000’ area.

From natural to cultural mires during the last 15 ka years: An integrated approach comparing 14C ages on basal peat layers with geomorphological, palaeoecological and archaeological data (Eastern Massif Central, France)

“…La Narce du B eage, and Gourddes-Aill eres fens). Furthermore, on these sites, pioneering mire phases, sometimes known as "transiting mires", also offer a very high biodiversity including underwater, floating, emergent and typical mire plants (for a case study, see Dendievel et al, 2019).…”

“…Giving an overview of past occupations and site densities over time is not easy especially because regions and periods are not documented with the same accuracy in the EFMC. Here, we compiled information from recent syntheses (Cubizolle et al, 2012;Dendievel, 2017;Dendievel et al, 2019;Jouffroy-Bapicot et al, 2013; Scholt es, PhD in preparation).…”

“…M ezenc Massif, around 7.5e6.8 ka cal. BP (Daugas and Raynal, 1989;Dendievel et al, 2019). In the northern zone, human impacts occurred most certainly during the Early Neolithic, but dwellings are mainly known since the Middle Neolithic (6.8e5.8 ka cal.…”

“…In spite of few archaeological evidence, early water management is highlighted by the catchment of water from the Pilat to the Monts d'Or to supply the city of Lyon (Lugdunum) and by small reservoirs devoted to agro-pastoral purposes on the uplands. During the Late Antiquity and the Early Middle Ages, a lower population density is deduced from fewer archaeological sites, but small towns and some large domains persisted while land use certainly changed (Catteddu, 2009;Dendievel et al, 2019;Phalip, 2002). From 1.3 to 0.5 ka cal.…”

“…95 %) (Reimer et al, 2013;Stuiver and Reimer, 1993). On some sites, the best interval for peat initiation was calculated by integrated Lithological and Palaeoecological Syntheses (LPS) implying a detailed pollen, macrofossil, diatoms, geomorphological and radiocarbon study at: La Narce du B eage (Dendievel et al, 2019), La Sauvetat, Le P echay, and Marais de Limagne (Beaulieu et al, 1984); Ribains, Collanges, Freycenet, and La Gimberte (Serieyssol et al, 2012;Tourman, 2007). Information was also obtained from textual archives (ARCH) for very recent mires (75e15 years cal.…”