Environmental drivers of the distribution of nitrogen functional genes at a watershed scaleEnvironmental drivers of the distribution of nitrogen functional genes at a watershed scale Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2015-11-062015enTo date only few studies have dealt with the biogeography of microbial communities at large spatial scales, despite the importance of such information to understand and simulate ecosystem functioning. Herein, we describe the biogeographic patterns of microorganisms involved in nitrogen (N)-cycling (diazotrophs, ammonia oxidizers, denitrifiers) as well as the environmental factors shaping these patterns across the Koiliaris Critical Zone Observatory, a typical Mediterranean watershed. Our findings revealed that a proportion of variance ranging from 40 to 80% of functional genes abundance could be explained by the environmental variables monitored, with pH, soil texture, total organic carbon and potential nitrification rate being identified as the most important drivers. The spatial autocorrelation of N-functional genes ranged from 0.2 to 6.2 km and prediction maps, generated by cokriging, revealed distinct patterns of functional genes. The inclusion of functional genes in statistical modeling substantially improved the proportion of variance explained by the models, a result possibly due to the strong relationships that were identified among microbial groups. Significant relationships were set between functional groups, which were further mediated by land use (natural versus agricultural lands). These relationships, in combination with the environmental variables, allow us to provide insights regarding the ecological preferences of N-functional groups and among them the recently identified clade II of nitrous oxide reducers.Δημοσίευση σε επιστημονικό περιοδικόhttp://creativecommons.org/licenses/by/4.0/FEMS Microbiology Ecology916 Tsiknia Myrto Τσικνια Μυρτω Paranychianakis Nikolaos Παρανυχιανακης Νικολαος Varouchakis Emmanouil Βαρουχακης Εμμανουηλ Nikolaidis Nikolaos Νικολαιδης Νικολαος Federation of European Microbiological Societies Biogeography--Effect of climate on Biogeography--Effect of climatic changes on biogeography climatic factors biogeography effect of climate on biogeography effect of climatic changes on Balance of nature Biology--Ecology Bionomics Ecological processes Ecological science Ecological sciences Environment Environmental biology Oecology ecology balance of nature biology ecology bionomics ecological processes ecological science ecological sciences environment environmental biology oecology