Isabelle Jouffroy-Bapicot

Optimal counting limit for fungal spore abundance estimation using Sporormiella as a case study

The use of non-pollen palynomorphs, and among them spores of coprophilous fungi, has become greatly important in palaeoecological studies. Particularly, the genus Sporormiella has been demonstrated to be the most valuable proxy for the presence of wild and domestic herbivores. This genus could also be used to determine livestock density and reconstruct pastoral pressure during the Holocene. Non-standard counting methods have been established to determine coprophilous fungal spore abundance in sediments. Moreover, these analyses are faced with the recurrent problem of setting the minimum counting sum as small as possible to save time. We researched the reliability of Sporormiella concentration estimates based on different counting sums, using low to high count samples. Box-plots indicate that the variability of inferred Sporormiella concentrations decreases progressively with increasing sums. Statistical comparisons show that the means of box-plots became stabilised after the counts have reached 300–350 exotic marker grains. Moreover, a count of 300–350 exotic marker grains is sufficient to produce a Sporormiella concentration estimate, whatever the amount. Finally, we propose that this counting limit is valid for other fungal spores as well.

2000 Years of Grazing History and the Making of the Cretan Mountain Landscape, Greece

Understanding the processes that led to the recent evolution of Mediterranean landscapes is a challenging question that can be addressed with paleoecological data. Located in the White Mountains of Crete, Asi Gonia peat bog constitutes an exceptional 2000-years-long sedimentary archive of environmental change. In this study, we document the making of the White Mountains landscape and assess human impact on ecosystem trajectories. The paleoenvironmental reconstruction is based on high-resolution analyses of sediment, pollen, dung fungal spores and charcoal obtained from a 6-m core collected from the bog. Multiproxy analyses and a robust chronological control have shed light on anthropogenic and natural processes that have driven ecological changes, giving rise to the present-day Mediterranean ecosystem. Our results suggest that sediment accumulation began during the transition from the Hellenistic to the Roman period, likely due to watershed management. The evolution of the peat bog as well as vegetation dynamics in the surrounding area were linked to past climate changes but were driven by human activities, among which breeding was of great importance. Charcoal analysis reveals that fire was largely used for the construction and maintenance of sylvo-agropastoral areas. Pollen data allow the identification of three main vegetation assemblages: 1) evergreen oak forest (before ca. 850 AD), 2) heather maquis (ca. 850 to 1870 AD), 3) phrygana/steppe landscape. Rapid changes between phases in vegetation development are associated with tipping-points in ecosystem dynamics resulting from anthropogenic impact. The modern ecosystem did not get established until the 20th century, and it is characterized by biodiversity loss along with a dramatic drying of the peat bog.

7000 years of vegetation history and land-use changes in the Morvan Mountains (France): a regional synthesis.

This paper aims to reconstruct the vegetation history of a middle mountain – the Morvan (Burgundy, France) – since the Neolithic (i.e. 7000 years). The results of palynological and non-pollen palynomorphs (NPPs) analysis performed on 10 peat cores document the main phases of human agro-pastoral practices and natural resources management which drove the formation of the cultural landscape of the Morvan Massif over time. To document the history of human activities at a regional scale, particular attention was given to the determination, the characterization and the graphical depiction of phrases of human impact. Both the quantification of the impact of human pressure and the chronological uncertainty of the different phases identified by pollen and NPP analysis were taken into account. This study reveals a clear human presence during periods that were formerly poorly documented, such as the onset of the Neolithic period, the Bronze Age, the early Iron Age and the early Middle Ages. It also sheds new light over periods for which there is better archaeological and historical knowledge, such as the widespread occupation of the massif in the late Iron Age, the cultivation of chestnut from the 11th to the 16th century and the impact of modern firewood exploitation on the forest.