If the population living within Portland's UGB grows more rapidly than the UGB around Portland expands, how would the per capita land consumption need to change to accommodate the new residents

The per capita land consumption needs to decrease.

Explanation:

The UGB in the question, short for Urban Growth Boundary, defines the boundaries that any city or urban area is planned to stay in.

If the UGB within grows faster than the UGB around the city expands, then the per capita land consumption ,which is the amount of actual space each person uses, needs to be decreased to adjust to the new residents.

I hope this answer helps.