The plants in a woodland will all host a variety of animal life. Oak trees alone, will support an amazing 400+ different invertebrate species, although not of course, necessarily all on one tree!
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A tree's value for animal life does not end with the death of the tree. Even such a seemingly mundane habitat as rotting wood, hosts about 1,700 different kinds of invertebrates in Britain.
Fungi and bacteria are an often overlooked component of woodlands. They are vital for recycling dead material into reusable nutrients to fuel new plant growth.
http://www.countrysideinfo.co.uk/woodland_manage/intro.htm
Managing Woodlands for Biodiversity
Animal diversity is to a great degree controlled by plant diversity. This is because the plants generally provide the architecture and structure of a habitat, as well as being the basis of food chains.
Plant diversity in woodlands can be encouraged by making sure there are a variety of light levels within a woodland from deep shade to open glades. Planting a variety of native trees will also enhance animal diversity because native trees support many more invertebrate species.