In thinking about the plan Leiningen created for his plantation, what does the water-filled ditch show about him?

He shows that Leiningen is a defensive minded strategist willing to do all in his power to protect his plantation from the invading ants.

Explanation:

'Leiningen And The Ants' is the story of a coffee plantation owner called Leiningen who upon hearing that an army of invading ants was coming to invade and destroy his coffee plantation, refused to chicken out and run, but rather chose to employ several defence mechanisms to defend his investment in the plantation.

The water filled ditch (also called Moats) around the plantation was the first line of defense employed by Leiningen to ward off the ants.

The ditch which was built 12 feet across the plantation was filled with water to act as a barrier to the ants reaching the plantation.

The ants, however, used their bodies to construct a bridge over the ditch on which they were able to invade the plantation

It shows that he has to evolve in order to struggle against nature to survive.

Explanation:

He believed he could defeat the elements of nature through his high intelligence by building a ditch that he could channel water with high pressure thereby forcing the ants to retreat.