As a Bay Area urban designer for four decades, I’m often called to design homes that are hardened against fire, which includes thinking carefully about vegetation within its defensible space zones. I’ve observed roughly 10 to 35 percent of a yard’s vegetation is removed or thinned to protect property and human life. That removal’s impact on biodiversity has not yet been fully studied, but a 10 percent reduction in habitat is significant.
Many habitat-supporting practices run counter to best practices for defensible space. Retaining brush piles, mulching with organic material, leaving downed logs and fallen foliage, and creating vertical layers of canopy trees with understory planting can all contribute to a fire ladder—the exact conditions defensible space is intended to reduce. So what can we do in areas requiring vegetation management? All of this has brought me to a central question: How can we create defensible space and support the natural world as much as possible?
First, we are not creating moonscapes. Plants are allowed in zones 1 and 2, so consider shifting toward a palette of wildlife-supporting native species. Place a rock pile to provide homes for invertebrates, reptiles, and amphibians. If you have limited opportunity for plantings, try what I call “superhost” plants, offering food and shelter to animals and ornamental and structural beautification for a yard. These are often considered relatively fire-resistant species if kept watered and pruned of deadwood. Most of my suggestions work on properties across the geographic range and ecosystems of the Bay Area, but where possible, use local plant stock to preserve regional genetics, and purchase from nurseries sourcing from your watershed…