To cut a tree 3D model without high poly, use low-poly techniques like Boolean operations, edge loops, or texture maps.
Boolean tools let you subtract simple shapes (e.g., a cube for a saw cut) from the tree without adding extra polygons. Edge loops help define clean cut boundaries, and texture maps (like normal or displacement) simulate rough cut wood—no more geometry needed.
For beginners, try Blender’s Boolean modifier: Create a basic shape for the cut, apply it to subtract from the tree. It’s easy to use and keeps poly count low.