Indeed. Where I live, it is used to rejuvenate the heather, not to
eradicate it.


Indded, that's why it's important to know how and when to use fire. I suspect ( with no data ) that if a heather moor was burned just as new growth was starting it would have the opposite effect. It probably behaves in the same way as grass, i.e stimulated if burnt when long but knocked back if burned as new growth. It' not something anyone's going to try though unless they outlaw shooting and give planning permission to build on heather moors ( I hope John Prescott doesn't see that suggestion ).