What is formed by all th ecosystems of earth ?

It is the biosphere, which is all the ecosystems of the earth

 In biosphere, it is the total organismic life and their entire species on which how they interact with the co-organisms. While biodiversity, is the different and varied living organisms and creatures across the ecosystem or the biosphere, on which is the composed the biotic environment. This may include now the hierarchy and organization among the species of the autotrophs and heterotrophs.

The correct answer would be they occur when the sun, moon, and earth are aligned. in spite of their name, these tides occur all year long.