Work with textures on meshes from blender or studio?

This may help:
https://www.youtube.com/watch?v=U3J-oYFdyqQ

well yeah it selects everything after going to edit more, so you press A to deselect, then press Select in the Materials tab then P

Problem I had before with this was it selects part of the trunk as we;;

You may need to go into Face Select mode and manually deselect the trunk faces you do not want/need.

So, to give a bit of direction: there are three option boxes to the right of Global drop down menu, if you mouse over them you should find one that says “Face Select”, click it and then you can easily select with a more forgiving outcome (if you misclick). Hold LShift to select multiple faces consecutively.