Monitoring arthropods diversity in the “Costières de Nîmes” viticulture landscape

Biodiversity loss in agrosystems is partly due to landscape simplification (field enlargement, hedgerows removal…) that led to a loss of heterogeneity of the overall landscape. The aim of this study is to compare biodiversity of different habitats and landscape configurations in order to target strategic conservation actions and their locations in viticulture landscapes to improve biodiversity. The arthropods taxon has been used to evaluate biodiversity dynamics because of its high diversity and supposed ability to rapidly react to landscape dynamics. Arthropods are identified through the RBA method (Rapid Biodiversity Assessment). Arthropod diversity is evaluated in five different habitats and measured by species richness and Shannon index. Within four different radii (50, 100, 150 and 200 meters) around each arthropod sampling site, landscape composition (relative percentage of each land cover type), structure (variability and heterogeneity indexes) and diversity (Shannon index applied to landscape) were analyzed through a Geographic Information System of land cover based on aerial photographs.

The results show significant differences in arthropod diversity among habitats. Cultivated habitats show lower values of diversity than semi natural ones. The landscape approach highlighted negative correlations between arthropod richness and proportion of fruit orchards at all radii. At the smallest scale (50m radius) a positive correlation is found between arthropod diversity and interstitial spaces (plot edges, headlands, roadsides…). Hence, semi natural habitats and non cultivated areas appear to play a major role in the preservation of arthropod diversity in agricultural landscapes. According to these results, landscape and biodiversity actions will be performed at the “Appellation” scale focusing on improving the ecologic connectivity between semi natural habitats supporting biodiversity.