Greed is a word that represents a key theme in this story. Ulrich's family owns a piece of land and has kept an ongoing feud with George's family about staying off of this land. But George inherits this two-family conflict and neither man does anything to end the feud. So, George continues hunting on the land in spite of Ulrich's disapproval. And the men are sworn enemies as a result of their mutually declared right to this piece of land.
Their greed to use the land for their own purposes is what fuels the feud. But that greed is supplemented by a habitual anger or enmity for one another. In other words, greed for the land and anger for one another are two supplemental feelings that feed into each other.
Greed connects this theme of anger/enmity and the notion of arrogance. The two men arrogantly feel they have a right to "own" or control this land. Given social laws about legal property, Ulrich has a written right to own the land, but George feels a practical right to it. In the end, in the grand scheme of nature itself, neither man really owns the land. And to be sure, neither man "controls" the land. In fact, the land itself (nature) is what destroys the men. The wind, the fallen tree, and the wolves have the last say. In their arrogance, the men think they control nature. This arrogance stems from their anger and from their greed to control land/nature. So, anger and arrogance are prominent themes in the story, but you can show how greed connects these themes.