Joint Colonization

I wondered why human beings and Ythrians had to divide Avalonian territories between them. At first, they settle in the Hesperian Islands because islands are less likely to hold fatal surprises than an entire continent and they settle on different islands in order to avoid friction while learning about their new environment. However, they look forward to dwelling together on the mainland.

But, when Corona is settled, Parliament and Khruath divide the continent between their species and Jack Birnam is told that he will have to stop visiting the Andromeda Range. Poul Anderson explains:

"While men and Ythrians could eat many of the same things, each diet lacked certain essentials of the other. For that matter, native Avalonian life did not hold adequate nutrition for either colonizing race. The need to maintain separate ecologies was a major reason why they tended to live apart."
-Poul Anderson, "Rescue on Avalon" IN Anderson, Rise Of The Terran Empire (Riverdale, NY, 2011), pp. 307-322 AT pp. 318-319.

Flying Ythrians can dwell in the mountains that human beings can  use only for recreation - but Jack has used the Andromedas for that. The happy ending is that, in the wake of a turbulent Avalonian storm, Jack saves the life of the Wyvan of Stormgate. The choth pays for a cure to Jack's allergy to Ythrians and makes him and his guests always welcome in the Andromedas which they call the Weathermother.

This source of friction is resolved but what of others?