Air New Zealand's making changes to two of its routes impacting South Island connectively from tomorrow

It's scrapping direct services between Wellington and Invercargill, forcing travellers to lay-over in Christchurch from now on.

The national carrier's also ending early morning flights between the garden city and Queenstown, and evening departures from Christchurch.

The changes will make it unlikely for people to travel and return from each city in a day.

Air New Zealand says the changes are down to a smaller aircraft taking over the route due to market demands, which cannot operate in the dark.