Corsican Palaeoclimate, Palaeoenvironments & Anthropization (COPPA)

Corsican Palaeoclimate, Palaeoenvironments & Anthropization (COPPA)

The collaborative program CoP²A, “Corsican Palaeoclimate, Palaeoenvironments and Anthropization” aims at reconstructing and evaluating past interactions between continental ecosystems, climate variability and land-use in Corsica for the last 15 millennia. The issue of this program has been defined around the following paradox: Corsica is the sole island still characterized by diversity of old and mature forests (with 29 % of forested area) in spite of: 
- A long history of human occupation (since the Mesolithic) with strong man pressure (agropastoralism, fires) 
- A high vulnerability of habitats due to the insularity 
- An overall Mediterranean hydrological deficit (promoting fires)

Therefore, compared to landscapes in Malta, Cyprus, Sardinia and even in the northern part of Mediterranean area, Corsican ecosystems are particularly well-preserved. It must be noticed that pioneer palaeoecological studies improved knowledge on past vegetation and climate changes but insufficiently for understanding potential factors which triggered the original trajectory of these insular ecosystems through the Lateglacial/Holocene because of the absence of relevant chronological framework together with a mono-disciplinary approach.

The goal of CoP²A program is to document with accuracy (and through a multidisciplinary approach) past dynamics of forests and woodlands and to reconstruct (with high resolution) holocene climate variability and human impact in the island by analyzing two series of palaeoenvironmental archives: 
- lacustrine and palustrine records, 
- long tree-ring series sampled in old populations of Pinus nigra sbsp. laricioFagus silvatica and Quercus pubescens.

The study of these archives was designed in “three work packages”:

Palaeoecological approach (coordinator F. Guiter, IMBE) 
This approach will be performed on sedimentary archives by studying both beetle/pollen fossil assemblages for reconstructing in detail past ecosystems dynamics during the Lateglacial and the Holocene. This will also allow to identify potential impact of past climatic episodes and to estimate the onset of agro-pastoral activities from lower altitudes to the upper part of mountains.

Sedimentological and geochemical approach (coordinator K. Tachikawa, CEREGE) 
The aim of this work package is to estimate and to quantify erosion processes recorded in the palaeolacustrine records (studied by palaeoecology): sedimentological and geochemical variability will be studied via chemical composition, color and density of sediments by using a multi-function XRF core scanner ITRAX. The high-resolution analysis will be combined with ICP-MS quantitative measurements.

Dendrological approach (coordinator: F. Guibal, IMBE) 
This independent approach aims at reconstructing past variability of palaeotemperatures and palaeoprecipitations at the annual resolution provided by long tree ring series. 
Particular attention will be paid on old populations of Corsican pines (Pinus nigra laricio) at high elevation, beeches (Fagus silvatica) and deciduous oaks (Quercus pubescens) at lower altitudes, which will be investigated for reconstructing hydroclimatic variations in Corsica from the medieval period to present day.

Finally, by coupling sedimentological, geochemical, palaeoecological investigations and tree-ring analysis, the program intends to characterize erosion episodes linked with changes in land-use, vegetation and past climate. The project duration is 3 years (financial support for the first year) and is complementary to a starting multidisciplinary paleoenvironmental thesis (on wetland sites in Corsica, Y. Poher, IMBE).