The aerial parts of plants –leaves, stems, flowers– are considered as the phyllosphere. This environment is oligotrophic and heterogeneous for microbes to live on. Resources are limited and unevenly distributed. Thus, different possibilities would explain : (1) competition is high and bacteria have low degree of resource overlap between them to allow coexistence (increased niche stabilisation); (2) competition is low and bacteria are metabolically dependent on each other or on certain taxa; (3) they associate randomly and can tolerate each other without impacting on each other’s population growth.
