In reply to Dave Cumberland:
it's rhizominous- technically an area is one big plant with lots of genetically identical shoots. This limits the effectiveness of cutting and its variants, like rolling, and means that small scale interventions have no real impact, as the plant just regrow with no long term impact. It was thought repeated rolling would deplete the nutrient store, certainly in sherwood it was widely practiced, but I think that idea was wishful thinking and an incomplete understanding of the plant. These days spraying is preferred.
A physical barrier, like plastic piling can limit the spread by blocking the roots, but the only partially effective technique is spraying with Azusulam / azulox which has an environmental cost. Decades of overgrazing, together with draining and burning have caused a dramatic increase in bracken in the Peak District and other areas managed for grouse, as it rapidly colonises the burned areas, aspecially on steep slopes where the burn has been very hot and led to local soil losses.
The bracken will then spread out into adjacent areas, particularly those areas which had high sheep densities ( this situation is improving, if slowly, with changed to subsidy regimes and a greater awareness of overgrazing). It's also a problem on commons in the lakes and places like the Shropshire hills where the graziers have less incentive to support long term sustainable land management ( a literal example of the tragedy of the commons!)
The toxicity is a constant problem when looking at management alternatives. Whilst some animals will flatten or even eat it, the toxins will harm even resistant animals in the long term and there are also concerns about bioaccumulation ,both in the animal and the environment. It is of course dangerous to walkers when spores are being release later in the summer from breathing them in, which makes manual management by volunteers recommended in the op potentially risky, which means it's tricky for landowners and official bodies like the NT to officially sanction the practice.
And of course it is supremely well adapted to take advantage of a changing climate
Post edited at 08:57