Nunc incrementa lente exeunt, festinatur in damnum

For Ramon Margalef, in the centenary of his birth. Why do not we find ecosystems in the atmosphere, as in oceans and continents? In the atmosphere, spores, pollen grains and micro-organisms float, most of them expelled from soils. But trophic networks are not established, nor are there large flows of energy and matter controlled by living beings.