A priori categorization of ponds and determinants of Odonates richness in a highly urbanized landscape: case of Paris city, France

Abstract

In the current development of urban ecology, few studies are interested of freshwaterecosystem. Taking ponds and Odonates as models, we investigated firstly changes in localvariables and species composition according to ponds localization in an urban context in theregion of Paris city, France. Secondly, we studied the relative importance of local andlandscape scale variables on α-diversity indices of Odonates using model averaging. Bothanalyses for adults and adults plus exuviae were carried out. We recorded 657 adults and 815exuviae belonging to 17 species that represent the entire pond assemblage of late seasonOdonata and 30% of the 57 species of the region. Three species (Sympetrum striolatum,Ishnura elegans, Lestes viridis) was common and abundant. Results show that environmentalcharacteristics of ponds are not very sensitive to their localization in an urban context. Sameresult is observed for species composition of Odonates. However, α-diversity analyses onglobal data highlight the importance of land use surroundings ponds. The increase ofurbanized landscape around ponds has a clear and negative impact on α-diversity indices.Different local scale variables are significant according to global or adults data. Theseanalyses also show that exuviae collections are crucial to fully understand the response ofOdonates. According to our results, we suggest that ponds in urban landscape are suitablefreshwater habitat for Odonates and we promote their creation in city