Without being thoroughly familiar with the legal issues nonetheless the following would be considered if such an issue occurred in my strata debacle.
1. The “very forceful chairman” could brusquely dismiss the question about his “reasoning” with – because it’s fair – while the only owner other than yourself who has turned up shows a slight waver in his bovine expression – which suggests agreement. (OC’s are more democratic than any other level of govt. and there is no rule I’m aware of that would not allow the tree owner to offer money, proxies or whatever as a success fee).
2. The square metre or less of land in which the tree trunk resides could be made common property which of course would be inaccessible to other owners except by trespassing on the surrounding land.
3. At least one council does not allow significant trimming of healthy trees overhanging footpaths or roads on safety grounds so in that case presumably the OC would be free from risk.
4. I’d start politely but assertively seeking proxies or better reasonable owners who are seriously willing to be active participants (get the proxy first, tell them it become invalid if they attend as participants) – partly on the “what next” principle and with only 8 units a chairman with a couple of proxies/followers can take control.
5. If it comes onto an agenda for a general meeting but is not clearly marked as a special resolution, do your best but knowing that if passed it should be rejected at the CTTT if someone is willing to pay $75/$150 for mediation /adjudication – but could be reversed if more than 25% of entitlements don’t vote against it later at a properly convened meeting.
6. I’d also start reading the Act, it’s searchable so reading the sections around words such as common, meetings, properly, special should be relevant.