Nitrogen cycle microbial communities in rhizosphere soils of Alnus glutinosa and Alnus cordata

The Dombes region is a French continental wetland in which rainfall decrease has been observed in recent years. Among the species emblematic of this continental wetland, the temperate alder tree species Alnus glutinosa is dependent on water supply and contributes to atmospheric nitrogen entry in the N-cycle via its symbiosis with the actinobacteria Frankia. If A. glutinosa populations were to decrease due to rainfall decrease, using another tree species as replacement could be considered, provided it could fulfil the same N-cycling functions. Alnus cordata, a Mediterranean alder species known to be more drought resistant, lives sympatrically with Alnus glutinosa in The Dombes region. In the present study, we aimed to assess whether the Mediterranean species A. cordata performs the N-cycle ecological function in the same way as the temperate species A. glutinosa in The Dombes wetland ecosystem. To do so, rhizosphere soils of both alder species were sampled and their microbial communities (16S and N-cycling functional communities) were sequenced.