Garden design can reduce wildfire risk and drive more sustainable co-existence with wildfire

Destructive wildfire disasters are escalating globally, challenging existing fire management paradigms. The establishment of defensible space around homes in wildland and rural urban interfaces can help to reduce the risk of house loss and provide a safe area for residents and firefighters to defend the property from wildfire. Although defensible space is a well-established concept in fire management, it has received surprisingly limited scientific discussion. Here we reviewed guidelines on the creation of defensible space from Africa, Europe, North America, South America, and Oceania. We developed a conceptual model of defensible space framed around the key recommended approaches to mitigate fire attack mechanisms, which address fuel types, amount, and spatial distribution. We found that zonation within the defensible space is commonly recommended; reduction (or removal) of all fuels, and particularly dead plant material, is usually suggested in close ( < 1.5 m; Fuel-free zone) proximity to a house. Conversely, in an intermediate space (1.5–10 m; Open zone), guidelines focus predominantly on minimizing fuel horizontal and vertical connectivity. Finally, in the outer part of the garden (10–30 m; Tree zone) trees can provide canopy shielding from ember attack and radiant energy, but management of on-ground fuel is still recommended. Evidence from the scientific literature broadly supported these defensible space design elements, although many studies were highly localised. Further empirical and modelling research is required to identify optimal zonation surrounding houses, and to better understand how garden structure, species composition and moisture status affects risk of ignition from embers, radiant heat, and flames.