Clara PLANCHER

THESIS :

Biodiversity and history of land‑use changes, modelling and spatialisation of pollen signatures for a retrospective approach to mountain agro‑pastoral landscapes (Vicdessos – S. France).

• PhD Supervisor: Didier GALOP (Research Director, GEODE UMR 5602 CNRS)
• Co‑supervisor: Florence MAZIER (Research Scientist, GEODE UMR 5602 CNRS)

 

Context :

The various impacts that human activities may have on biodiversity are still poorly understood. While they may be responsible for biodiversity loss, some activities, such as mountain pastoralism, turn out to be generators of biodiversity. At the heart of scientific debates, the fight against the erosion of species and habitat diversity in mountain areas requires a better understanding of how our activities influence this biodiversity.
For this, it is necessary to take a step back and to examine the spatio‑temporal dynamics of biodiversity, and how it has responded to successive and diversified human activities in the past.

It is therefore essential to deepen, at different spatio‑temporal scales, the work aimed at highlighting the effects of past land use on landscape fragmentation, and on the structure and functioning of terrestrial plant ecosystems, and to analyse their capacity to respond to socio‑environmental changes.
However, scientific knowledge in this field is still scarce and often relies on data that do not go back beyond the last fifty years, which does not allow the full range of processes influencing biodiversity to be taken into account.

Faced with this issue, palynology, the study of pollen grains and spores contained in sedimentary archives, is legitimately positioned as one of the main methods for acquiring diachronic data over several centuries. It thus makes it possible to provide certain answers to conservation biology.The main criticisms directed at palynologists concern the lack of spatio‑temporal resolution of pollen data, as well as the difficulty of quantifying and spatialising pollen information to reconstruct the evolution of the spatial characteristics of vegetation.
Although new modelling approaches (Landscape Reconstruction Algorithm, LRA) make it possible to quantitatively reconstruct the evolution of vegetation cover for a spatial scale defined around sampling points, no method allows access to the spatial structure of vegetation from pollen. Thus remains the question of an appropriate method to reconstruct the spatial distribution of land‑use types over time, together with their dynamics and their spatial and temporal uncertainties quantified at all points in the studied landscape.
 

Goals :

In this context, the PhD focuses particularly on plant and landscape diversities. It is based on an interdisciplinary approach combining paleoecology, historical ecology and geography.
This resolutely methodological project aims to develop a method for studying long‑term (several centuries) landscape changes in a mountain workshop area, the valley of the Bassiès ponds, integrated into the Haut‑Vicdessos Human‑Environment Observatory.
This area, rich in biodiversity, is undergoing profound changes in land‑use systems and landscapes, notably with the rapid abandonment of agro‑pastoral activities, reflected in a reforestation dynamic, accompanied by a change in the floristic assemblage and a decrease in plant diversity.
 

EXPERIENCES :

• February – July 2018: Master 2 Internship at the GEODE laboratory, From pollen to landscapes: towards a spatialised reconstruction of present and past land‑use types. (Methodological development for the spatialisation of pollen information.)
• April – May 2017: Master 1 Internship at the Institute of Evolutionary Sciences of Montpellier (ISEM), Reconstruction of the palaeoenvironmental dynamics of the Lapsou peat bog (Cantal, France). (Traditional palynological study of a peat bog.)
• March – April 2016: Assistant at the Animal and Plant Ecology Laboratory of the University of Quebec at Chicoutimi (UQAC).

 

CURSUS UNIVERSITAIRE :

• 2016 - 2018 : Master in Biodiversity, Ecology and Evolution, Specialisation Chrono‑environments and Paleoecology (CEPAGE), University of Montpellier (34).
• 2015 - 2016 : Third year of Bachelor’s Degree in Ecology and Organismal Biology in an exchange programme at UQAC, Chicoutimi (Canada, QC).
• 2013 - 2015 : First and second years of Bachelor’s Degree in Ecology and Organismal Biology, University of Montpellier (34).