Jurassic and the Great Tree

We come to Pavonis Minor, invited by the Burul'chasi, descendants of the first wave of human settlement. They have successfully resisted intrusion into their territories for many years, yet now they want someone to come, now they want someone to see. "Only one man," they said, through their intermediary. "Only one man may come." And so we three are here, riding in the body of one. Which is all very well until the three begin to disagree...