The results of the 2013 LiDAR survey are to hand and not in dispute. It's the results of the latest survey, carried out in 2016, that are not yet available.
Meanwhile, the mayor has a programme underway to plant a million new trees during the current term of council, which finishes in late 2019.
Another activist, Wendy Gray, made the same "one third lost" claim to a council meeting in February this year. She noted that in 2013 there were 4,640,000 trees in Auckland, which meant the third we have supposedly lost would total 1.5 million.
Gray showed that meeting a photo of a freshly cut stump. It was a mature exotic tree in Walmsley Park in Mr Roskill, cut down to make room for new stormwater drains. She asked, couldn't those drains have gone around the tree?
Mayor Phil Goff answered her. He said the "stormwater" system was actually a stream that used to be channelled through pipes underground. Now the council had "daylighted" it: brought it back to life, creating a welcome environment for birds and other wildlife, and for people to enjoy. Yes, a few exotics had been cut down but, as part of his million trees programme, they were planting 50,000 new trees in the park.
This wasn't environmental vandalism, said Goff. Walmsley Park was being made an immeasurably richer and more appealing green space in the city.
So, trees are complicated. But how complicated?
Mels Barton was back with another submission for council this week. She's a short woman with a mohawky haircut who speaks with a bristling fierceness, and she said the mayor's million trees project "might be a panacea but it's not funded, so you're not planning to implement it".
Besides, she argued, the strategy is wrong. "If you remove 80-year-old trees and replace them with saplings you're not replacing like with like, you're not going to get any of the benefits of those 80-year-old trees for another 80 years."
That's true, but isn't it also a bit irrelevant? We need to preserve as well as plant, sometimes favouring one approach and sometimes the other. And sometimes, because of disruption to drains or for other reasons, we also need to remove.
Barton also took the opportunity to repeat her "one third lost" claim, but this time with a significant difference. She limited it to the city's urban boundaries. Even then it seemed hard to credit.
The 2013 data showed that 18 per cent of the city within the urban boundary was tree covered. If Barton is right, it's now something less than 12 per cent.
Cr Chris Darby, who chairs the council's planning committee, says he doesn't know if the figure is right but, told me "my own observation is we are experiencing a de-greening of urban Auckland".
But how is that possible? The council is nearly halfway through its term: where are those million new trees?
Meanwhile, officials took a report to council this week called "Managing and Protecting Trees in Auckland". It recommended, wait for it, that council change nothing about its current approach.
Even though it said that would result in "a potential minor reduction in Auckland's tree cover".
That means more significant trees will be cut down without their owners telling anyone first. Even when a consent is required, mostly it will be non-notified. Nobody gets to find out until too late.
The officials said there were two other options. One was to actively increase the size of the Schedule of Notable Trees. But that would cost money and none has been allocated. So they didn't recommend it.
In fact, council right now is sitting on requests from the public to add 40 trees to the schedule, but has no intention of doing anything about those requests.
The other option was to ask the new government to reinstate the provisions of the Resource Management Act for "general tree protection". It used to be that trees of various species were automatically protected if they were of a certain size. Note that "Protection" didn't, and still doesn't, imply no one can touch the tree. It simply means that if you own one you need a consent to chop it down.
The previous government removed that protection in 2015.
Not surprisingly, Barton called the officials report "a self justification for doing absolutely nothing" and wanted to know where the analysis of 2016 LiDAR data is. Why produce such a report without it? She had a point.
Goff was also sceptical. Why was there such a big gap between the report and the view of the Tree Council?
The council's planning manager, Phill Reid, said, "My professional view is the tree cover in Auckland is relatively stable." He said there had been a reduction in the Waitemata area, but a lot of new trees planted "in the greenfield areas".
To its credit, the council instructed officials to get that LiDAR analysis completed "by August", so it could decide what to do next. It also asked officials to start talking to central government officials about the RMA.
Two of my favourite trees in my street were cut down last year. One was a giant pohutukawa, the other a mature magnolia. The owners needed the space in their backyards.
They weren't my trees. But when you live in Auckland – most parts of it, at any rate – it's not quite that simple, is it? Neighbours don't share in the ownership of each other's trees, but you do enjoy a kind of collective pleasure in them.
How should the law deal with that? Why not have a full schedule of large and significant trees, on public and private land? And if an owner wants to chop one down, why not ask that they go through a publicly notified process first? Explain their purpose, answer any critics, look for a consensus solution, allow someone to adjudicate with an eye to both property rights and the greater good?
Meanwhile, are we losing our trees? It's absurd the council doesn't know and that tree protections are so weak. It's also very odd the essential facts are not in the public domain.