They aren't defending land though, they are really defending access to resources contained in that land. If you drop a plant on empty land with no relevant reso

They aren't defending land though, they are really defending access to resources contained in that land. If you drop a plant on empty land with no relevant resources for it, the plant will die. It will not become a landowner. Land ownership is a very recent concept in our history. Most of human history on this planet happened with no concept of owning land.