wonder if it'd work to have the saw and a clamp on an arm. get rid of branches near the place you want to saw with a chain-naginata or a drone with sharp exposed metal propellers, then the saw-drone flies up, extends the arm and clamps it around the tree. then a rotary saw extends into the space within the clamp. because the saw is on the side of the drone, the tree will topple away from it.
orange: labels
white: thing
black =: because excess " " are removed
carrying arm=servo====arm
=\======== /______/_
=\=======/=0]=/==\==\
========[ = ]=0===} [=] -clamp on piston
======== \= ]=/\=_/ \
=========== /= \== \
=========motor=\==sawblade (extended, mounted below or above clamps).
=========on===fixed clamp
=========piston
Can't use metal propellers on living branches. Props tend to grind or bash living things rather than slice things. Don't think of living trees like the dead pieces of lumber you can buy at a hardware store, or firewood. Living wood versus dead wood acts differently.
I have seen a drone with clamp + saw. The problem is that branches or tree trunks tend to fall in unpredictable fashion the higher up in the air that you are cutting. It's the reason why people in the profession ties up the wood they are cutting so a guide on the ground can get it down in a predictable manner.
You also need a clamp to release extremely fast to make that work (There is bunch of high pressure valves that could help there but that increases the weight of the drone which decreases flight time.) You don't want the cut piece of wood to get caught in the clamp as it's opening which would be harmful to a drone's flight.
I was talking about this with a crew that was removing the trees at my workplace. They talked about a presentation where multiple drones were used to do the job. Problem was the time it took and the expense of each drone and it's upkeep cost make the idea ludicrous to them. The idea behind it is sound, it just impracticable at this point.