To determine the most cost-effective way to balance urban tree canopy and infill outcomes, this study tested two policy options for the new Planning and Design Code:
# Option 1: Draft Planning and Design Code policy for one onsite tree per allotment
# Option 2: Offsite tree planting, via an offset scheme.
The ‘One Tree Policy’ proposed in the new Planning and Design Code is expected to deliver economic, amenity and liveability gains to the Greater Adelaide community valued at $26.4 million (Benefit Cost Ratio 1.7), and is therefore a worthwhile initiative for government to consider.
In the General Neighbourhood and Suburban Neighbourhood Zones, the majority of households can meet the proposed tree requirements without incurring any new costs to their house footings.
Consideration could be given to implementing more nuanced policy options to minimise upfront costs in the cases when a homeowner will incur a net cost as a result of tree policies i.e. in locations with highly reactive soils and small minimum set-backs. This may include introducing an optional offset scheme which, as formulated in this study, would deliver estimated gains to the Greater Adelaide community of $187.2 million.