On July 2, a wildfire ignited along State Route 166 just east of Los Padres National Forest in San Luis Obispo County. The fire grew rapidly over the following hours and days and went on to burn nearly 81,000 acres—making it the largest in California so far this year. In fact, the fire is twice as large as the two biggest Los Angeles area fires in January, the Palisades and Eaton Fires, combined. Those fires destroyed 16,251 structures while the Madre Fire has destroyed one due to its remote location.
We decided to take a closer look at this incident, dubbed the Madre Fire, since it burned a small section of Los Padres National Forest, much of the Carrizo Plains Ecological Reserve, and a significant portion of the Carrizo Plain National Monument.
Quick Summary
- The fire started in a cattle-grazed area dominated by non-native grasses along State Route 166 and was human-caused.
- The general area has seen some large fires in the early twentieth century as well as in the late 1990s, but the Carrizo Plain National Monument portion of the burn area has seen few fires since record-keeping began. This is by far the largest fire to affect the national monument since it was established in 2001.
- The fire burned mostly through shrublands and grasslands as well as some blue oak woodlands and savannas closer to the La Panza Mountains.
- The majority of native shrubs in these areas can resprout after fire, with some relying on dormant fire-cued seed banks to repopulate burned areas. A notable exception is the California juniper, which is common in the Caliente Mountains. The fire left many patches of shrubland there unburned and these areas will serve as important seed sources for junipers and some other species to repopulate burned portions of the landscape.
- Blue oak woodlands in the northern portion of the fire appear to have experienced mostly lower-severity fire.
- We expect that the fire had relatively minimal direct impacts to wildlife due to the ability of birds to fly away and the fact that most small mammals (as well as other types of wildlife) are burrowers that can escape the fire by retreating underground.
- Despite being human-caused, the Madre Fire offers a good opportunity for researchers to study the impacts of fire on a variety of ecosystems and species.
- Damage to cultural and recreational sites is unknown at this time.
Ignition Location and Potential Causes
No cause for the fire has been officially determined, but it was certainly due to human activity. We confirmed the approximate ignition coordinates shown in public databases by comparing 3D imagery in Google Earth to footage from an ALERTCalifornia camera on Plowshare Peak, which caught the early minutes of the fire’s progression. The Madre Fire clearly started around 1 p.m. immediately adjacent to the highway and and rapidly spread east, propelled by the prevailing winds, according to the Watch Duty app that day.
While it is impossible to say from the footage exactly what caused the ignition, we definitely rule out lightning. The last significant lightning storm in the region was about a month prior, though all of the known lightning strikes during that event were farther southeast than the ignition location. In some ecosystems, under the right conditions, lightning strikes can ignite plant material that then smolders for days or weeks before being fanned by winds to become a full-fledged wildfire. But given the proximity to a highway and the ignition’s location in a grassland, the chances that a lightning strike from weeks or months earlier held over this long are virtually nonexistent.
It is much more likely that a driver passing by accidentally or deliberately started the fire by throwing out a lit cigarette or using other means to ignite the grasses along the road. A car idling in the grassy area along the shoulder of the highway could have also started the fire. Wildfire investigators may release an official determination about the cause, but it may be one of the countless fires that will forever have an undetermined cause due to a lack of evidence.
The fire also notably started on private land before moving into Los Padres National Forest and the Carrizo Plains Ecological Reserve. This is a typical pattern for the region, as Los Padres National Forest is affected by more wildfires starting on external lands than any other in the country. Most of the large fires that have affected Los Padres National Forest in recent memory started on private or state-owned lands: 2016 Soberanes Fire, 2017 Whittier Fire, 2017 Thomas Fire, 2024 Post Fire, and 2024 Lake Fire.
Role of Non-native Grasses
One aspect of the ignition is clear, however: it happened in a grassland area dominated by non-native grasses such as wild oats (Avena spp.). The combination of these flashy fuels and moderate winds made the fire’s rapid rate of spread in the early hours inevitable. In fact, the entire landscape in this area is particularly dry for even this time of year. Just look at the comparison of satellite imagery from late June 2023 and late June 2025 below:
We had significant rains in early 2023, and there was a staggering display of wildflowers at the Carrizo Plain National Monument that May and early June. In the satellite image from that year, you can see how much water was still left in Soda Lake, while the lake was bone dry at the same point this year. And more subtle differences can be seen in certain areas, including the Madre Fire’s approximate ignition location and most of the Cuyama River corridor that runs along the highway there.
Interestingly, this area has been grazed since at least the 1990s (that’s as far back as we can see with high resolution satellite imagery). You can even see cattle in the 2021 Google Maps Street View image of the spot where the fire started.
We bring this up not to blame the landowner but rather to highlight that even grasslands subject to routine cattle grazing are flammable under the right conditions. We often hear from anti-environmental groups the phrase “log it, graze it, or watch it burn.” Here we see that you can apparently graze it and watch it burn.
The bigger issue here is that grasslands across this entire region are completely dominated by non-native grasses. When we posted about the Madre Fire on social media the day after it started, we mentioned that it started in an area comprised mostly of non-native grasses. Someone commented, “Non native or native grass, it don’t matter.” But it does matter. These annual grasses dry out earlier in the year and are more ignitable compared to natives that tend to be perennial bunchgrasses. Most fires in this region start in areas dominated by non-native grasses like wild oats, ripgut brome, or cheatgrass and then spread into chaparral and other adjacent ecosystems.
Furthermore, non-native grasses have been shown in study after study to increase fire occurrence and frequency across the western U.S., especially in chaparral and sagebrush ecosystems. As fires become more frequent, especially in native shrublands, many native species that rely on the soil seed bank to repopulate an area cannot persist with short fire-free intervals as they need plenty of time to grow to maturity and produce enough seed before the next fire. The result is the slow erasure of chaparral and sagebrush systems over a period of decades or centuries, particularly at lower elevations and areas closer to cities, neighborhoods, and roads. And while this is largely due to an increase in human-caused ignitions, climate change and other factors compound the situation by reducing water availability in these ecosystems.
Area’s Fire History
The last major fire that occurred in this vicinity was the 1997 Logan Fire, which started in August of that year near Rock Front Ranch. The fire was caused by target shooting on private property, and it ended up stretching across a 50,000-acre area from Alamo Creek Road near Twitchell Reservoir on the coastal side of the mountains to the Carrizo Plains Ecological Reserve on the eastern side. The Logan Fire and Madre Fire ignition points are only about 3 miles apart, and the fires overlap across about 15,300 acres.
Before that, the western one-third of the Madre Fire area burned in a fire in 1922. That same week, a large 115,000-acre fire burned just south in the Sierra Madre Mountains. Newspapers at the time noted that the fires were burning ranch lands used for grazing, including the Chimineas Ranch that would later become part of the Carrizo Plains Ecological Reserve. Other large historical fires that burned in areas nearby include a 12,300-acre unnamed fire just west in 1921 and the 22,300-acre Spanish Fire in the Sierra Madres in 1999.
The eastern portion of the Madre Fire, in the Carrizo Plain National Monument, has seen little fire activity since record-keeping began. Being one of the most remote and unpopulated areas in the entire region, this area has probably experienced fewer human-caused ignitions compared to more populated areas closer to the coast or even more inland toward the Central Valley. The few, relatively small fires that have occurred in this part of the Madre Fire area were mostly in the grasslands across the inland foothills of the Caliente Mountains and along the Carrizo Plain itself. The fascinating juniper and oak shrublands and savannas in the higher elevations of the Calientes have probably gone well over a century without experiencing a major fire.
Impacts to Plants
The Madre Fire burned a large area, but simply stating the number of acres burned fails to tell the whole story. First, we need to consider what types of ecosystems actually burned. A quick GIS analysis shows that about 57% of the fire area is shrubland, 35% is grassland, 7% is oak savanna or woodland, and the remainder is sparsely vegetated (desert-like, barren, and roads). Of the 46,100 acres that are shrubland, over 12,000 acres can be characterized as some type of California chaparral—the same broad ecosystem category found across most of Los Padres National Forest. Chaparral comes in a variety of flavors, and the one you can find in the western portion of the Madre Fire is dominated by chamise (Adenostoma fasciculatum).
We see very typical fire patterns when looking at satellite imagery of the area from June 9. Areas dominated by chaparral have little to no green in the post-fire images. Fire tends to naturally burn intensely in mixed chaparral, killing most of the aboveground biomass. And as long as fires do not occur too frequently, most woody species can persist without much trouble. Chamise is a prime example. This very common shrub is what we call a “facultative seeder”—it can be top-killed by a fire but quickly resprout from an enlarged, partially buried woody mass called a burl. Many or even most of the mature individuals tend to survive the fire and resprout. In addition to this ability, chamise also has a large dormant seed bank stored in the soil, and these seeds are stimulated by chemicals found in charred wood. So not only will you see adult shrubs resprouting, but you will also see countless seedlings come up during the first rainy season after the fire.
Another 14,500 acres is some type of scrub, mostly coastal sage scrub dominated by California buckwheat (Eriogonum fasciculatum) as well as a desert scrub dominated by different species of saltbush (Atriplex). These ecosystems are quite open and relatively low growing, with substantial herbaceous plant cover.
The shrublands in the Caliente Mountains are dominated by California juniper (Juniperus californica) and Tucker’s oak (Quercus john-tuckeri), though other native shrubs such as desert almond, hollyleaf redberry, elderberry, purple sage, various types of saltbush, ephedra, California buckwheat, and even bigberry manzanita are scattered across the rugged area. Most of the plants listed above can resprout after being top-killed by fire, though bigberry manzanita is an excellent example of an “obligate seeder” that can only repopulate an area through fire-stimulation of a dormant seed bank. Tucker’s oak and California juniper are definitely the most abundant of the large native shrubs in the Caliente Mountains, however. While Tucker’s oak can easily resprout following fire, California juniper has no such ability. This conifer also does not build up a dormant seed bank in the soil like chamise or manzanitas, so the only way it repopulates an area is by seeds being brought in by birds and mammals.
The good news is that, based on post-fire satellite imagery, it looks like many large patches of the shrublands in the Caliente Mountains were either entirely unburned or burned at very low severity. This means that there will be plenty of sources of seeds for plants like California juniper to spread into nearby burned areas. This will definitely take some time—we will probably not see significant juniper seedling establishment until 10 – 15 years post-fire. And it will take much longer than that to fully replace the old individuals that were killed by the fire. In the meantime, less shade-tolerant native herbaceous plants will enjoy some of the new canopy openings between Tucker’s oaks and other resprouting shrubs.
Blue oak woodlands and savannas cover much of the northwestern portion of the Madre Fire area. Blue oak (Quercus douglasii) is capable of resprouting after being top-killed, though how much resprouting occurs across a burned woodland varies quite a bit. Regardless, we actually see that most of these blue oak woodlands and savannas do not seem to have burned intensely. It may be hard to tell because of the resolution of the satellite imagery (every pixel of the raw imagery represents nearly 1,100 square feet), but the canopy cover appears to be largely intact and still green after the fire. The understory of these woodlands certainly burned, which is why they look darker than the pre-fire imagery, but the green looks roughly the same as before upon close examination. You may notice white dots scattered across the post-fire image—these are actually where trees that were dead before the fire began were turned to bright ash.
Lastly, there are the grasslands that burned. These areas appear as the blackest spots in the post-fire satellite images due to the lack of ash produced there. Where shrubs and trees dominate, some amount of combustion of woody material happens and produces ash, which makes those areas look grayer. This is completely normal, but it does not tell us much about what to expect with plant regrowth in grassland areas. Most native herbaceous plants in these areas were dormant by the time the fire started. Many species likely did not even emerge over the winter and spring due to a lack of rain or other conditions. These grasslands will almost certainly look more like they did before the fire faster than the other ecosystems that burned. The real question is whether non-native plants will benefit from the fire, which is something that should be monitored and studied over the coming years.
Impacts to Wildlife
The Madre Fire area is home to several species of animals, including some endangered species. Fortunately, most animals have effective strategies for dealing with wildfire.
Birds are perhaps best suited for avoiding direct impacts as they can simply fly away as needed. It also helps that the fire started at the very end of bird nesting season for this area. How birds repopulate burned areas varies wildly between species and ecosystems, making it difficult to establish expectations for the coming years. Common shrubland species like California Quail will be back in the burned chaparral and juniper-oak shrublands much sooner than you might think. In the western portion of the fire, chamise and other chaparral species will resprout and quickly produce enough vegetation to provide cover. In the Caliente Mountains, the prevalence of unburned patches scattered across the juniper-oak shrublands will provide “refugia” for many bird species that will in turn help disperse the seeds of plants like California juniper into adjacent burned areas.
Some birds will likely increase in burned areas compared to unburned areas over the next couple of years due to an expected increase in fire-following herbaceous species (which themselves provide food and increase flying insect abundance), including birds like Lazuli Buntings and some types of hummingbirds. Other species will stick to the patches of unburned mature shrublands while woody vegetation regrows nearby. Mammals, particularly small mammals, have more difficulty escaping a fast-moving fire. But east of the Sierra Madre and La Panza Mountains, most of the common small mammals spend their time in burrows during this hot, dry part of the year. The different species of kangaroo rats can all easily avoid the direct effects of fire by retreating to (or simply staying put in) their burrows, and they may benefit from fire in interesting ways. These rodents also hoard seeds either in their burrows or in scattered caches, which may provide food while vegetation is temporarily depressed.
Other burrowing animals in this area include the San Joaquin kit fox, San Joaquin antelope squirrel, American badger, blunt-nosed leopard lizard, and various tarantula species. There is much less research on how fire impacts these different species, but we expect they can similarly avoid fire like kangaroo rats.
The largest animals in the area include black bear and mountain lion in the western portion of the fire, tule elk and pronghorn in the Carrizo Plain National Monument portion, mule deer, and coyote. The tule elk and pronghorn spend most of their time on the Carrizo Plain itself rather than in the mountains where the fire primarily burned—and both species can quickly and easily move long distances to escape the flames. The other species mentioned above are also generally able to flee from oncoming fires without much difficulty, especially in areas with less habitat fragmentation (e.g. roads, highways) like where the Madre Fire burned. However, it is important to understand that some animals will inevitably be killed by fire—the question is whether direct mortality significantly reduces population numbers over the long-term and how well individuals utilize the burned landscape in the following years. The Madre Fire may offer a good opportunity to conduct further research on population dynamics in burned and unburned areas over time.
Impacts to Cultural and Recreation Sites
The Madre Fire encompasses campgrounds, trailheads, and at least one prominent rock art site, most of which is in the Carrizo Plain National Monument. The entire monument remains closed to the public, so we still do not know exactly how some of these areas were impacted. The most up-to-date post-fire satellite imagery we have does not have a high enough resolution to give us much information either. However, it is likely that the rock art at Painted Rock—perhaps the most culturally significant location in the entire monument—escaped unscathed due to the protective shape of the rock itself. Even the satellite imagery suggests that some fire suppression efforts were focused there to ensure that fire did not get into the inner portion of the horseshoe-shaped formation where the rock art is located.
Selby Campground and KCL Campground are both within the fire’s perimeter, but it is unclear whether any tables or bathrooms were damaged. Selby Campground did not have much vegetation to begin with, so hopefully damage to facilities is minimal there.
Suppression Impacts
Our analysis of post-fire satellite imagery and incident management data indicates that about 83 miles of bulldozer lines were created across the national forest, ecological reserve, and national monument as part of suppression operations. A little more than half of the total bulldozer mileage was outside of the fire perimeter (not all of these lines are shown on the map below because they were outside of the map area). Most of these lines cut through grasslands, though a few miles of chaparral and coastal sage scrub were bulldozed in Los Padres National Forest.
We were also able to measure about 27 miles of fire retardant drops, largely on the western side of the fire. These were just the lines we could see in satellite imagery from July 9, but it is very likely that additional retardant was dropped in areas that eventually burned over.
There is good indication that “Minimum Impact Suppression Tactics” (MIST) were used in the Caliente Mountain Wilderness Study Area within the Carrizo Plain National Monument, with the exception of a couple of miles of fire retardant drops around the southeastern end of the fire. There was no bulldozer use within the wilderness study area as far as we can tell.
Post-fire operations will involve repairing bulldozer lines and areas impacted by suppression efforts. However, bulldozer lines can take many years to revegetate, often visually standing out much longer than the impacts of the fire itself. Interestingly, the fire moved across a little over 100 miles of existing roads without stopping. This is a good reminder that the presence of roads in a particular area in no way guarantees that fire suppression will be more effective, especially if the fire is wind-driven and spotting long distances. Combined with the fact that fires are more likely to start along roads—as was the case with the Madre Fire—protections for roadless areas are especially important.
Final Thoughts
The Madre Fire burned a variety of habitats across three pieces of public land: Los Padres National Forest, the Carrizo Plains Ecological Reserve, and the Carrizo Plain National Monument. Some of these areas have not experienced fire in many decades but are naturally adapted to fire regimes characterized by long fire-free intervals of up to a century or more. Regrowth across the burned area will be highly variable, with faster revegetation in the chaparral and blue oak woodland dominated areas on the western side of the fire compared to the more arid scrub and shrublands to the east. While regrowth of California juniper will be likely be painfully slow, we are glad to see that many patches of this ecosystem persisted through the fire unscathed. These areas will undoubtedly act as crucial nuclei for repopulation of less fire-adapted plant species over the coming decades. But how the ecosystem will fare under continued warming due to the climate crisis is unclear.
We will do additional assessments of the fire area after it reaches full containment—the fire is no longer growing, but firefighters are still working toward 100% containment—and some of these public lands are reopened to the public. The months and years ahead will offer good opportunities for post-fire research across this unique landscape.
The Madre Fire has also demonstrated once again that human-caused ignitions along roads, particularly in areas dominated by non-native grasses, is a pressing concern in our region. Federal funding is still mostly spent on fuel reduction in relatively intact native ecosystems away from homes and communities. ForestWatch will continue to push for more focus on ignition prevention as well as community-centered efforts such as structure hardening, defensible space, and alert/evacuation system improvement.
