Posted By Luke. Sorry to take up valuable posting space - just found it out. If anyone is interested then general rule of thumb is as follows: Fencing should be along a line 1m beyond the vegetation or tree crown spread, with 2.3m high steel mesh or panel fencing, mounted on scaffold framework set 600mm into the ground as anchoring, with backstays at 3m centres. A3 Signs should be fixed to each enclosure at 9 metre minimum intervals and should state: "Protected tree zone, no storage or operations within fenced off areas"