What's the minimum forestal mass required to generate land wildlife?

What’s the minimum forestal mass required to generate land wildlife? I don’t think a single tree can generate land wildlife.

Is it enough with seven contiguous trees? Seven like, in this picture, a contiguous mass:

  o   o

o   o   o

  o   o

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Also what would be the necessary forestal mass required to bring a single hunter hut to 100% productivity without generating any excess wildlife? In this case I understand this depends on the forestal mass exact form and the distance to the hunter hut, but I find interesting if only approximate or intuitive answers are given.