A Hastings District Council spokeswoman said the bark and branches falling off the tree indicated it was "showing signs of its age".
The council was engaging an independent consultant arborist to assess the tree and "help give direction on its future".
The poplar was planted in the 1870s and is one of the oldest and largest of its kind in the country. It is listed as a notable tree on the New Zealand Tree Register.
The tree once held the title of the tallest tree of its kind in the country before the top of its canopy was trimmed in 2018 "life-saving surgery" to extend its life as long as possible.
About 10 per cent of the tree canopy was removed under advice from independent arborists who were engaged when there were movements in its base.