Later stage species can invade a site, become established, and grow to maturity in the presence of those predecing them. They can do so because these later species have a greater tolerance for a lower level of resources than the earlier ones. Such interactions lead to communities composed of those species most efficient at exploiting resources either by interference competition or by using sources unavailable to other species. The climax is the final or stable community in a sere. There are thre schools of thought with regards to climax.
Every region has only a single climax community towards which all communities are developing.
Climate is the determining factor of vegetation and therefore, the climax of any area is solely a function of the climate. This school holds that many diffeent climax communities can be recognized in a given area. This school is a variation of the polyclimax school. It emphasizes that a natural communityis adapted to a whole pattern of environmental factors. The Climax patterntheory holds that a community of climax types, varying gradually along environmental and are not neatly separable into descrete climax types.