There is disclosed a system and methods of use for quickly and efficiently excavating, cross-cutting, splitting, and loading or stockpiling tree stumpage and other tree or organic materials, as well as for performing ground cleanup operations. One embodiment provides a stump harvester for attachment to a distal end of an excavator arm. The stump harvester may include front and back jaw assemblies configured to pivot between open and closed positions. The back jaw assembly may include a knife arm having a cutting blade that extends along a majority of a front side of the knife arm. A centerline plane may bisect a cutting edge of the blade. The front jaw assembly may include a planar-aligned dual anvil configured to sheath the cutting edge of the blade when the front and the back jaw assemblies move into the closed position. Other embodiments are disclosed.