Wistmans Wood itself is one of the last, and oldest, remaining stunted oak forests in the UK. There is some evidence that the woodland once covered the whole of Dartmoor, cleared by hunter gatherers around 5000BC.
The trees, stunted and twisted as they are, are taller than they were 500 or so years ago when they were described to be no taller than a man.
If you enter the woodland, do so with caution so as not to damage any habitat or greenery. If you have a dog with you it is best not enter at all as the woodland is home to a large population of adders.
The woodland is part of several preservation schemes (SSSI, NCR, & Wistmans Wood National Nature Reserve), none of which expressly forbid entry but in order to preserve the woodland and keep access for future generations please act responsibly.