The interactions between the species forming a biocoenosis consist of their mutual relationships. Those existing between a biocoenosis and the abiotic factors of its environment are, to a certain extent, shared by all the species of the biocoenosis (e.g. oxygen, water, mineral salts, or standard interval of physical variables like temperature, humidity or pH for example) at disposal in the environment. Last but not least, the interactions between the abiotic factors supporting the ecosystem significantly affect the taxonomic composition of the biocoenosis. We will now specifically focus on the interactions between the species forming a biocoenosis.