An artist's impression of what the Mangaone Stream pathway could look like upstream of Pioneer Highway with some selective planting.

Gaps are appearing in Palmerston North's canopy of trees, and residents are being asked to tell the council what they think of plans to plug them.

Its vegetation plan is out for consultation, with a focus on public spaces where the council can control what happens.

Council policy planner Michael Duindam said as private properties were carved up for infill, the pressure was on the council to make up for the trees that were lost.

Warwick Smith/Fairfax NZ How the Mangaone Stream pathway currently looks.

"We have seen quite a lot of change in the last five to seven years. We've moved from a 70-30 ratio of greenfields development to infill, to where infill is almost taking over as the most popular choice."

There was often also pressure from developers to remove street trees to form new driveways.

Duindam said living in well-treed areas made people feel better, and contributed to a healthy, attractive environment.

Some streets had been identified as character streets for their outstanding plantings, such as Batt St and the student precinct between Ferguson St and College St.

Duindam wanted to know whether residents put high value on the plantings in other streets, that with a little extra care, could become outstanding.

"But we find that often the less affluent areas tend to miss out, and that's one of the challenges."

The council has voted to spend $30,000 a year over its $60,000-a-year maintenance budget to increase street tree plantings.

The plan looks at reserves and walkways for opportunities to have better planting, both of trees and understorey plants.

Duindam said some of the city's waterways looked like "drains first and streams second", and there was scope to make them much more attractive.

One of the important functions the plan would play would be identifying appropriate plants for particular areas.

The city's silver birches, for example, would need to be gradually replaced, because of the problems they caused for allergy sufferers.

Only 17 per cent of the city's trees were natives, and that would be boosted.

The plan would help avoid repeats of problems such as the now-felled plane trees in Broadway, which as well as contributing to the bird dropping issue, had deep roots threatening underground services.

"They were the wrong type of sub-species for the location."

Feedback on planting of berms was also welcome.

Consultation will be largely informal and online, through social media and council staff appearances at public events.