Seven pohutukawa about 15m, aged between 20-30 years old, and four 9m tarata aged 15 years old were felled. A branch was cut off an eighth pohutukawa and there was damage to the surrounding vegetation.
The value of the felled trees was almost $63,000.
During the disputed facts hearing, Environment Court Judge Jeff Smith heard evidence from Kent and Cutfield, the latter has also pleaded guilty to the same charges.
Kent claimed he never instructed Cutfield to fell the trees but acknowledged they had discussed pruning and thinning them, and also claimed not to know they had special ecological values despite receiving a letter about it from council in 2009.
Cutfield insisted he had acted under instructions from Kent to thin out and trim the trees so he could have a better visual view of the harbour while seated in his spa pool.
He said he did as instructed and got paid $900 for the job.
Kent's lawyer Michaela Milner unsuccessfully argued for a discharge without conviction, saying he was not the principal offender.
The council's lawyer Adam Hopkinson said the total cost of the prosecution was $50,000, which included investigation and legal costs.
The council had also allocated $9300 to try to preserve the felled tree stumps - but the chances of their survival was slim.
Mr Hopkinson said it would take 20-40 years for the canopy to recover to a similar state and asked for a sentence which sent a clear deterrent message to Kent and others.
Judge Jeff Smith told Kent he preferred the evidence of Cutfield, describing him as a "naive, truthful man" who had shown genuine remorse.
"I have absolutely no doubt that the work was carried out under your instigation Mr Kent, and in my view you were the principal actor in this matter," he said.
The judge said his offending was "very serious" and Kent's actions had been reckless as they resulted in significant loss not only in terms of the replacement cost of the trees but he had "imperilled" their chances of survival and damaged an outstanding ecological area.
Judge Smith fined Kent $45,800 plus $265.78 court costs and $226 solicitor's fees, and also ordered him to pay $5000 reparation. He fined Cutfield $1500 and sentenced him to 200 hours' community work after taking into account his lack of ability to pay a larger fine.