The local environment of a tree strongly determine its productivity, meaning that tree individuals growing in a species-rich neighbourhood produce more wood than those surrounded by neighbours of the same species. Particularly impressive is the finding that the interrelations of a tree with its immediate neighbours induce higher productivity of the entire tree community (i.e. the forest stand), and that such local neighbourhood interactions explain more than 50% of the total forest stand productivity.
competition is less prevalent in species-rich neighbourhoods and that species-rich neighbourhoods can even lead to facilitation by e.g. an improvement of the microclimatic conditions or by positive interactions with soil fungi.
— source tu-dresden.de