Parts of South Auckland have lost nearly 10 per cent of their trees in just a few years due to development in areas already well under minimum standards for canopy cover.
Over the same period, many of Auckland's more-established suburbs saw substantial increases, such as Devonport with a 14 per cent boost in tree cover.
The data is contained in a report released Thursday by Auckland Council, which analysed LiDar (Light Detection and Ranging) surveys between the years 2016-2018, and compared it to a similar survey taken back in 2013.
It will be presented to the Environment and Climate Change Committee today.
While it appeared to put to bed fears Auckland had lost as much as a third of its trees since changes to the Resource Management Act in 2012 took away blanket protections on private land, the growth in cover was particularly uneven.
The report also found the vast majority of increases were on public land, and losses on private land.
There was also a substantial decrease in the overall height of trees, indicating many mature trees had been felled, with younger trees taking their place.
Overall it found canopy cover - measuring growth above 3m - across the region's 16 central wards had increased by a net 0.5 per cent, or 60ha, to 18.4 per cent.
This was well below the 30 per cent long-term goal set out in the Urban Ngahere Strategy.
The data did not include the Waitākere Ranges, Waiheke, Aotea/Great Barrier, Rodney and Franklin, all of which had seen substantial development.
Devonport saw the biggest percentage growth, gaining 46ha to take canopy cover from 16 to 18 per cent of the ward. Again, well below the 30 per cent target, but above the minimum 15 per cent.
Meanwhile, Ōtara-Papatoetoe lost 26ha or 8 per cent over the same period, but while it was already the second-most-bare ward it remained on 9 per cent cover overall.
Māngere-Ōtāhuhu has the least canopy cover overall, with just 8 per cent, and still lost a further 28ha or 6 per cent.
The largest loss by area was in Hibiscus Bays with 125ha, or 5 per cent of canopy compared to 2013. Howick lost 82ha, or 7 per cent.
Only one ward, Kaipātiki, met the council target, with 31 per cent cover.
Eleven met the 15 per cent minimum, while the five South Auckland wards all fell below.
Tree Council chairman Sean Freeman said the loss of taller trees was particularly concerning.
The proportion of trees less than 10m high had increased by 11 per cent since 2013 to 75 per cent of the urban forest canopy.
By 2016 only 17 per cent of trees were higher than 10m, 6 per cent over 20m, and 1 per cent 30m.
The report also did not provide detailed information about exactly where the losses were occurring. So while work on public land was clearly having an impact, there were fears for the 61 per cent on private land.
"We are extremely concerned that without incentives and regulations to encourage private landowners to retain existing mature trees as well as plant new ones this trend will continue until there are very few large trees left in Auckland."
Freeman said this needed to be addressed in the RMA, with blanket tree protections reinstated.
Auckland Council head of parks Mark Bowater said the report showed Auckland was "holding our own" when it came to tree loss.
Previously there had been fears as much as a third of canopy cover could have been lost in recent years, but Bowater said this proved that was not the case.
The biggest areas of growth were on public land, which showed the council's planting and protection plans were working.
As most of the data was collected over 2016 to 2017, and only measured trees above 3m, it also would not have yet captured the full benefits of the council's Million Trees programme.
But it also meant full impacts of the RMA changes which meant trees without any formal protection on private land could be legally removed, which came into force in Auckland in 2015, would not have been captured.
Bowater acknowledged the "geographical disparities", which he said correlated with areas of high housing development.
"It is part of the nature of growth," Bowater said.
Across Auckland, urban areas expanded 8 per cent between 1996 and 2012 and a further four per cent between 2012 and 2018/19.
While the council could do little to prevent tree loss on private land, it advocated for developers to retain the urban forest, and looked to increase planting in public spaces and urban design.
One example was at Totara Park, where the council and volunteers were turning retired farmland into an "ecological area of high value for communities and the environment".
The report now also provided the council with the data to address inequities.
"This is the most accurate picture of tree canopy cover we have ever had," Bowater said.
Report authors raised concerns that "no ongoing [nor long-term] data collection programme existed", but Bowater said this current report would be the start of a regular monitoring programme.
Environment and Climate Change committee chairman Richard Hills said addressing inequality would be a "real priority".
"I want children across Auckland, no matter the suburb, to be able to walk home from school sheltered from the sun. What we prioritise now will have an impact well into the future."
It is unclear at this stage how the council's planting programmes will be affected by the announced budget cuts.