Here’s How We can Defend LA’s Fire-Intercepting Line Backers
September 2024. By JT Wilkinson: Trees provide an outsized role in fire-defensive landscapes. When canopies catch embers en route to homes, they can delay or prevent home ignition and give firefighters needed moments to intervene.
We know of no more skilled ember-interceptor than our native Coast Live Oaks. Their small, leathery leaves retain hydration in high, dry, heat making them exceptionally difficult to ignite. Incredibly dense, their canopies keep embers from passing through them. Slow to ignite (even when chopped and cured as firewood!) Coast Live Oak’s dense trunks and branches are notoriously slow to ignite and burn.
These exceptional defenders can live well-upwards of 200 years, protecting generations of Angelenos. How can we return the favor? Happy you ask!
Help them hydrate.
Establish young Coast Live Oaks with regular hydration. Once established, Coast Live Oak will need supplemental water only once a month if there has been no rain. If you have enough space for an oak’s expansive root system and a bioswale, the feature can help Coast Live Oak maintain health on rainfall alone.
Tip: Support Coast Live Oak with deep water spikes or a separate hydrozoned irrigation system that recognizes their dislike for being water during high heat.
Keep soil airy and cool.
LA’s frequent droughts and water restrictions can render soil hot and hard. This can challenge even well-established, hearty oak trees. These challenges are further complicated by the trend of placing stone at the base of trees and application of synthetic turf.
Tip: Keep soils happy environments for Coast Live Oak by leaving their leaf litter to serve as mulch. This is the only fertilizer they need. Weed grasses from under their expansive canopies, and, where appropriate, consider planting shade loving native plants like Alumroot and Swordfern.
Trim with care.
A keystone species, Coast Live Oak are prime habitat often filled with nests from February through July. We avoid trimming in nesting season. Trimming large branches or during oak’s fall growth period can expose them to infestation and disease. This leaves a very limited timeframe for tree trimming.
Tip: Assess Coast Live Oak health and structure in early summer, and make trims in July or August. Note that California law protects oaks, and permits are required for their removal.