The PC Chair is entitled to express an opinion about the tree being too costly and provide costs whatever that means. Gifting of land by the developer should not incur a cost but what in respect of the tree would be too costly? Relocating it, getting the Principal Authority to confer a TPO on it? If the PC has barely enough money to pay for whatever the Tree cost is, the Council might decide it is worth using reserves or making an increase to the precept. What is certain is that the Chair is not empowered and cannot unilaterally decide that the cost, whatever it actually relates to, can or cannot be paid, whatever he personally thinks about it.