What is the climax stage of an ecological succession?

The climax stage is the stage of the ecological succession in which the community of an ecosystem becomes stable and does not undergo important changes. In this stage the biomass, the photosynthesis rate and the cellular respiration reach their maximum levels and therefore the net primary production (NPP = organic material made by the producers - organic material consumed in the cellular respiration of the producers) tends to zero. At the climax the amount of oxygen released by photosynthesis is practically equivalent to the oxygen consumed by respiration. (This is one more reason why it is wrong to say that the Amazon Rainforest, an ecosystem at climax stage, is "the lung" of the earth. Other reasons are: lungs are not producers of oxygen; the algae and cyanobacteria of the phytoplankton are the major producers of the molecular oxygen of the planet.)