Identifying tree groups for ongoing protection in Upper Hutt.

Like many councils around the country, the Upper Hutt City Council had been grappling with the question of how to provide for urban tree protection after the Resource Management Act was amended in 2013. Under the amended Act, tree protection in urban areas was restricted to individual trees and tree groups, clearly described together with the location of the affected allotment. In Upper Hutt, this meant that the existing blanket tree protection rule, which applied to trees over a certain size in certain residential areas, was lifted in August 2015. The council wanted to continue with some form of tree protection in the affected neighbourhoods and decided to seek assistance from Boffa Miskell in identifying tree groups which qualified for ongoing protection.

Boffa Miskell was already familiar with Upper Hutt, having previously undertaken landscape and tree assessment work for the council but the new legislative framework presented some challenges.

“The new RMA provisions require a greater level of certainty as to the specific values of identified tree groups and the precise location of the trees within them. That brings more complexity and potential cost,” says Boffa Miskell project leader and landscape planner, Rhys Girvan. “Our challenge was to devise a sufficiently robust yet cost-effective methodology.”

To begin with, the Boffa Miskell team worked closely with council officers and councillors to develop evaluation and ranking criteria. According to Rhys, scale was crucial in the evaluation: each tree group was considered within the wider context so that landowners would understand the values of their individual trees in terms of both their own property and their neighbourhood.

To streamline this assessment, our GIS specialist Pen Moore mapped indicative tree groups by analysing canopy cover and estimated tree heights to provide a portable online database which could be updated in the field. With this head start, Rhys and ecologist Tessa Roberts carried out the evaluations and ground-truthing in just two weeks, inputting new or revised data directly into the database using iPads. Pen then developed a semi-automated process for summarising the data of the 261 tree groups that were eventually identified. The summaries were given to landowners during the consultation phase that preceded the Plan Change notification in December 2015.

There were no appeals after the council hearing and the Plan Change is now operative, giving both Council and landowners more certainty about what will need to be considered when processing tree removal applications.

Rhys says the Upper Hutt City Council was very supportive in developing a workable and robust methodology.

“Together, we’ve established that the tools are available to coherently assess tree group values and save on time and cost involved in tree group assessments.”