With boughs overhanging the hut, DoC had chopped it down and cut it up into firewood, rather than move the hut, Mr Lusk said.
People familiar with the area were grief-stricken: "It's like you've lost an old friend."
A small group of nine has been organising the April 6-7 wake, and he thinks at least 50 people will attend.
One man who visits Buller regularly from Austria, was horrified to discover "his" tree had gone. He plans to fly out for the wake.
"DoC's excuse was health and safety," Mr Lusk said. "But it's been there for 500 years and (survived) about 20 major earthquakes."
With the hut hidden from view as trampers approached, the kahikatea acted as a beacon.
"I wouldn't know where to take people now to see a tree of that size in Buller."
DoC Buller area manager Bob Dixon said the department had invested $75,000 transforming the 1960s ex-forestry hut.
Moving the hut would have been "phenomenally expensive" in a constrained site; "and we have plenty of trees". It was standard operating procedure when there was a risk to people.
"We are not interested in Mr Lusk grandstanding, particularly when the safety of people is uppermost."