Centre for the synthesis
and analysis of biodiversity

A centre created and developed by the FRB

Dans la série des Séminaires Scientifiques du CESAB

Salle de projection du Forum, Europôle de l’Arbois, Aix-en-Provence

Mardi 3 décembre, 11h—12h


«
Plant functional diversity of permanent grasslands in France: the search for environmental drivers. »
DIVGRASSsmallPix

 

Par Cyrille Violle, chercheur au CNRS-CEFE Montpellier, groupe de travail DIVGRASS : « Diversité végétale et fonctionnement des prairies permanentes ».

 

 

Résumé :
Permanent grasslands cover about 10 millions of hectares in France, but, like in most of Europe, they have been receding over the last decades due to the combined effect of urbanization and changes in agricultural practices. These grasslands are remarkable areas for biodiversity and serve a large number of functions and ecosystem services: food resources for animals, carbon sinks in the soil, water filter, erosion prevention, cultural value, etc. As part of the DIVGRASS project, we aim at combining and synthesizing a large amount of existing data on French grasslands (plant taxonomic and functional diversity) from different sources and to identify key drivers (i.e. topography, soil, climate, management) of the geographical distribution of grasslands as well as the spatial patterns of their taxonomic and functional diversity.

 

We assembled ca. 50 000 vegetation relevés comprising 3 800 species and covering the main beta-diversity gradient of French grasslands. These relevés were combined to the worldwide functional trait database, TRY. Main moments of functional diversity were calculated at the community level (Community Weighted Mean [CWM], Community Weighted Variance [CWV]) and the relationships with climatic and soil variables were examined. We showed that CWM of the Specific Leaf Area (SLA) was significantly dependent on annual sum of Growing Degree Day (GDD) and water availability. The magnitude of this relationship was highly sensitive to the combination of data availability and the width of the bioclimatic gradient. Despite these issues, this study provides a first comprehensive overview of the large-scale trait environment relationships and paves the way to the mapping of CWMs at a kilometric scale.

 

We offer a striking example of the relevance of an eco-informatics platform to assess bio-geographical (functional) diversity based on plant community and trait data. This quantitative analysis allows us to identify the main gaps in current biodiversity databases and provide guidelines for further sampling efforts. It also opens new avenues to refine the representation of the temperate C3 grasslands within climate and biogeochemical models.


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