We're doing a pretty big landscaping project - putting in about 1200 sqft of pavers and a 70' x 3' rock retaining wall. Our landscaper ran into our 35 year old Japanese Maple with his tractor and broke off one of the larger branches. Part of the branch is still there, but we're afraid that the whole branch will need to be removed since there is about a 12" split in the remaining wood. If that branch needs to be removed, that half of the tree won't have any branches and I don't think it makes sense to keep the tree. So far they have apologized but haven't offered anything else. Is there any standard for compensating us for a mistake like this? OR, what is reasonable for us to ask?
Contractor responsibility and owner responsibility are always a difficult balance. The owner invites a contractor onto the property and by doing so must expect the unforeseen; there are generally a wide variety of contractors available for a work to be completed and it's the owner bears the responsibility of the choice.
Once committed to a contractor, the invitee must be made aware of what is important in the landscape. It is not possible to protect all the worms and frogs on a property, but particularly valuable trees can and should be pointed out to the guest on the property and part of the contract becomes "remove the bulbs and replace on completion of the work" or "erect a visual barrier around the tree and wrap the trunk before commencing work - use only small machinery close to the tree". In many cases this is termed due diligence; without it the complaint falls apart.
If the contractor is reputable you may find that getting a quote from an arborist to rectify the damage as much as possible without replacing the whole tree and inviting the contractor to share in the cost might lead to a successful outcome.
I'm assuming you're in USA. Did your project involve a contract? Was there any language about unintended damage to property?
Anyways, the landscaper should be insured against damage to customer property. I would have a certified arborist appraise the tree. I'd ask for the landscaper to compensate you for the value of tree plus costs to remove it. They can file this with insurance if they want.
At the very minimum, I would think they should pay to have the tree removed, and purchase and install a new one for you.
If not, I'd consider taking them to small claims court, or just not hiring them again.