The Santa Cruz Mountains are world-famous for their iconic redwood forests. Naturally, we want to ensure these magnificent trees stay healthy and strong. But as we near the fourth anniversary of the CZU Lightning Complex fire, it’s easy to lapse into dread. What if we face another devastating wildfire season with impacts nearby? People in our region have grown used to being anxious in summer and fall, and the prospect of another big blaze feels all too inevitable and real.  

Over the years, my colleagues have written of the collaborative methods POST and our partners are undertaking to restore habitat and practice sustainable forest management close to home. Knowing these complex efforts are underway is reassuring. Still, there are so many terms and concepts to grasp (especially if you, like me, studied poetry—and not science—in school). We thought a primer—replete with a glossary of terms—would be helpful for anyone eager to brush up on the basics. 


In mid-August 2020, lightning ignited fires across the Bay Area. The CZU Lightning Complex spread through the heart of our local redwoods, burning through almost all of the 9,000-acre San Vicente Redwoods (pictured here). 

What Does a Healthy Forest Look Like?

Imagine yourself in a vast old-growth redwood grove. As you stride through the landscape, the air is cool and moist. The natural spacing between the trees is expansive, and a broad canopy lends protective shade. The nearby forest floor is lush with ferns and other native plant life. Beneath your soles, the big trees’ roots intertwine, coursing with shared nutrients. Under such healthy conditions, the forest and its inhabitants live their best lives. 

It’s important to note that such groves are not — and have never been — flame-free. Fire has been a part of our landscape for millions of years and is crucial for many of our local ecosystems. Coast redwoods rely on lower-intensity fire and have adapted to take the heat. Their hearty bark and high tree crowns shield them well. What’s more, new saplings take root after a blaze. 

What Challenges Do Local Forests Face?

Back in the early 20th century, loggers cut down entire sections of our region’s forests. Many of these landscapes have yet to fully recover from these outmoded logging practices. To make matters worse, land managers have long tried to suppress fires, doing more harm than good. Without regular fire, dry vegetation builds up in our forests. When paired the frequent droughts and rising temperatures brought on by climate change, these conditions can lead to high-intensity wildfires. 

Despite these gloomy circumstances, POST and our partners are not losing hope. In POST-protected San Vicente Redwoods, we’re working alongside public agencies, other conservation nonprofits, universities, timber companies, tribal groups, water agencies, a Fire Safe Council, local governments, and a trained volunteer corps. Together, we’re exploring innovative and long-standing methods to protect communities in fire-prone areas and make forests more resilient to climate change. 

Managing Fuel Loads

Multiple problems occur when the landscape gets overcrowded with plant life. Redwoods must compete with each other for sunlight, water and nutrients, and as such they grow stressed and unhealthy.  When there’s too much vegetation in the understory, a ground fire can move into the trees’ canopy where it becomes much more dangerous and destructive.  For this reason, we employ multiple strategies to reduce dry matter (also known as “fuel loads”) and promote forest health.

Some of our fuel reduction strategies mimic the disturbances (like low-intensity fire) that once naturally pared vegetation. The hope is that, with less fuel to ignite, fires won’t reach into the canopy and zip through the treetops. (If you’re interested in delving deeper into this topic, our partners at Cal Fire, without whom this work would be impossible, have an extensive, user-friendly guide.)

Forest Thinning

Grounded in conservation science, this technique allows us to bring balance to the forest by removing thin, unhealthy trees. With fewer trees competing for resources like sunlight and water, heartier redwoods have a better chance to thrive and create old growth conditions that are naturally more resilient to fire.

Invasive Plant Management

Invasive species — that is, those non-native plants that cause harm to the environment — are troublesome for several reasons. They displace the native plants our local animals rely on to survive.  They may be toxic to wildlife when eaten. Some even change the soil’s chemistry, making it less hospitable to other plants.  Because they accumulate quickly, they increase the potential fuel in the forest. This can lead to more frequent, severe fires. Opting to remove these invasives makes the entire forest ecosystem more resilient.

Prescribed Fire

When weather conditions are optimal, we set an intentional, contained burn. First, we clear vegetation and construct a firebreak to control the blaze’s spread. Next, a “burn boss” — someone who is uniquely qualified to plan, organize and execute the burn — sets a fire within the contained area and carefully tracks its spread.  This efficient practice mimics natural processes, restores ecological functioning and clears the forest of flammable debris. It can benefit plant life, stimulating the seedbank and imbuing the soil with rich nutrients.  There are several methods of prescribed fire, including open fires, burn boxes and cultural burning.

Cultural Burning

A time-honored form of prescribed fire that occurs in the San Vicente Redwoods is cultural burning.  Calling upon deep ancestral knowledge and indigenous science, members of the Amah Mutsun Tribal Band employ traditional fire practices that nurture the environment. Among the benefits of these methods: They help culturally important plant species to grow.

Shaded Fuel Breaks

We create shaded fuel breaks by mechanically clearing excess brush while pruning or leaving the boughs above. This process leaves less combustible material or “ladder fuels” for flames to climb and burn through. Because fire naturally moves uphill, we place these shaded fuel breaks along ridgelines. When a blaze reaches these barer strips of land, it cools and slows down substantially. These clearings also provide a foothold where firefighters can work to contain a fire.

Processing Fuel Mass with Targeted Fire

Mechanical fuel reduction projects create plant-based waste, aka “biomass,” that needs to be disposed of. Here are some techniques we’ve employed at San Vicente Redwoods:

Air Curtain Burner

One method is to incinerate the debris in an Air Curtain Burner. Its emissions are nearly smokeless, consisting of water vapor and biogenic carbon dioxide. When the weather is unideal for prescribed burning, Air Curtain Burners are an efficient alternative.

Pile Burning

This strategy involves burning mounds of material that result from fuel management activities such as forest thinning, creating shaded fuel breaks or cutting down hazardous trees over roads. We clear a buffer around each mound to make sure the pile burns don’t spread into nearby vegetation. As added safety measure, we typically reserve this practice for wetter wintry months.

Maintenance to Support Activities

To support the aforementioned forest management strategies, ongoing monitoring and maintenance work is essential.

This includes:

  • Conducting roadwork to allow service and emergency vehicles onto the property while reducing erosion into creeks
  • Planting seedlings to help maintain redwood habitat by giving trees a head start to outcompete the faster growing scrubby and more flammable plants, such as ceanothus and tanoak, that tend to dominate the post-fire forest floor
  • Having water tanks ready to go on site


While wildfire season continues to be harrowing, it reassures me to know that my colleagues at POST  — alongside a regional network of partners  —  are working tirelessly to protect, enhance, and restore the forest. We’ve learned from the effects of the CZU fire, and years later, we’re adapting and still going strong.

About Post

Peninsula Open Space Trust (POST) protects open space on the Peninsula and in the South Bay for the benefit of all. Since its founding in 1977, POST has been responsible for saving more than 87,000 acres as permanently protected land in San Mateo, Santa Clara and Santa Cruz counties. Learn more

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