Losing the lollipop look

Lush trees are universally seen as a desirable part of any streetscape but increasingly, space restrictions mean canopies often end up lollipop-shaped.

Fraser Miller, from Rough and Milne Landscape Architects in Christchurch, didn’t want that for the work he’s doing on the Avon River Precinct in the central city.

“I really dislike that look,” he told Landscape Architecture Aotearoa. “But it’s hard when you’re growing trees in concrete so we had to find a way round that problem.”

His solution was to use an underground modular unit made from recycled post industrial waste.

Stratavault soil cells fit together like Lego blocks, bearing the load of everything above ground while allowing roots to flourish underneath. It’s design means planting can be done using ninety percent topsoil, instead of say ten percent with the rest being made up of rock.

“You end up with large, healthy trees that grow to their mature size,” Miller says. “Whereas before you saw a tree in a paved area where space was restricted end up with the lollipop look.

“Often canopies are reflected in tree roots. For me it’s a no-brainer.”

Miller had used the product previously when he worked in Tauranga six years ago.

It’s also increasingly popular in Auckland. And Miller’s keen to see it used more in Christchurch.

System importer Paul Malcolm, of Metrogreen, says the product’s constantly being refined and developed, which has reduced the cost of it considerably in the last ten years.

It used to work out at around $700 per cubic metre; it’s now down to $250.

“In the past people have developed buildings and streets, then all of a sudden they think ‘actually we must have some trees’,” Malcolm says. “So they’ve been planted right on the edge of the road where they either grow and ruin the infrastructure, or they don’t grow at all.

“The system allows us to provide uncompacted soil for the tree beneath the asphalt or concrete.”

He says it’s also allowed landscape architects and arborists to work happily with engineers, each being able to design or plan the streetscape they want to without hindering the other’s project requirements.

“Joe Public has no idea what’s involved with growing a treescape in a street without causing a lot of infrastructure damage. It’s really a lot of work.”