Introduction

The recent increase in destructive wildfires in California has stirred up fearful questions about climate change, drought, and management practices. There are many conflicting theories about how to mitigate deadly wildfires, and this study planned to show whether or not prescribed burining and fuel management may be a piece of the puzzle. Early into this study, it became clear that the state of California prefers to allocate their resources to mitigate the effect of wildfires thruogh supression and containment rather than prevention techniques. For example, fire ecologist Dave Kinateder said, “Cal Fire spends the bulk of its resources battling fires rather than practicing preventative measures” (Cart, 2018).

The objective for this reaserch originally was to answer whether or not fire prevention methods such as prescribed burns or fuel management techniques are proven to decrease the frequency and intensity of wildfires in California. As I carried out the methods for this reaserch, my objective became slightly different. First, I randomly selected 7 counties in California with a random number generator and began reviewing their 2018 California Strategic Wildfire Plans. After looking for correlations between comprehensive fire plans (or lack thereof), and frequency and intensity of wildfires, I examined location difference to explain the variability of these results. Many scientists have proposed that fuel management practices should be location-specific and built off of extensive local research regarding vegetation makeup. For example, the California Chapparal Institute said, “Prescribed fires do have a place in mixed conifer forests, but NOT in chaparral and sage scrub plant communities” (Halsey, 2013).This study hopes to show that utilizing location-specific fuel management practices can help return an ecosystem to its natural fire regiments.

Definitions

“Fuel” - Buildup of underbrush, that is highly flammable, and allows wildfires to spread and increase in intensity.

“Prescribed burns” - the controlled and monitored burning of certain areas to reduce fuel loads, and prevent susceptibility to larger wildfires. A tactic of fuel management.

Do prescribed fire acres have an effect on the amount of acres burned from wildfires?

I used a linear regression method to analyze how the acres of prescribed fire would affect total acres burned from wildfires from the data obtained in all 7 Strategic Wildfire Plans. The results show that an increase in prescribed fires exponentially decreases the total acres burned from wildfires. These reuslts validate our initial belief that prescribed fires decrease wildfire acres-proving part of null hypothesis 1 wrong. I removed an outlier from this graph–of 277,884 acres burned in Shasta County which was due to the horrific and vast Carr Fire which was 10 times larger than our next highest value of total acres of wildfires burned.

Statistical Results: The R-squared and adjusted R-squared value obtained from this regression is .8881 and .8508 respectively, showing that the data closely fit the exponential decay regression line. The standard error values for the Intercept and PF are .2843 and .0004 respectively, showing the precision of the regression line to the actual datapoints.

Acres Burned as a function of Fuel Management Acres:

Next, I examined how the acres of fuel management would affect total acres burned from wildfires. The right half of this figure shows that an increase in prescribed fires rapidly decreases the total acres burned from wildfires-invalidating the second part to Null Hypothesis 1. The leftmost point on the graph is inconsistent with the data because Santa Barbara county’s Strategic Wildfire Plan had no data record of acres of fuel management. It is unlikely that there were no fuel management operations in Santa Barbara.I also removed the same anomaly from the dataset: Shasta County’s 229,651 acre Carr Fire far exceeded the acres of wildfires in the other datapoints. Shasta’s datapoint can be considered unrelated to this study perhaps because a fire of this scale can not be prevented from prescribed burns and fuel management techniques.

Number of Wildfires as a function of Fuel Management Acres:

This figure compares how the acres of fuel management affects the number of fires burned from wildfires (instead of acres). There is no significant pattern between the acres of prescribed fires and number of fires across counties. This is likely due to several other factors and a lack of counties that we analyzed.

Number of Fires as a function of Prescribed Fire Acres:

In this figure, I analyzed how the acres of prescribed fire would affect the number of fires burned from wildfires. Contrary to my belief, this graph shows a positive correlation between the acres of prescribed fires and the number of wildfires. It is more likely that there are more prescribed fire acres in locations that are more prone to wildfire damage. This graph also does not show how big these fires are. For example, Riverside has the highest number of fires. But I noticed that all of Riverside’s fires were extremely small. I speculate that although fuel management may not decrease the number of fires, it may decrease the relative size of fires. It is possible that with an increase of fuel management, fires will less likely grow rapidly. On the other hand, Nevada-Yuba county had by far the most acres of fuel management and only had 4 fires, which was an anomaly in the trend.

Location Implications for Fuel Management

Santa Barbara

Chaparral

Chaparral

Santa Barbara lies in a chaparral biome–with flat plains, rocky hills, mountain slopes, and some grasslands. The fact that Santa Barbara had little information or data on fuel management and prescribed fires likely has to do with the fact that certain fuel management techniques such as fuel removal is much more difficult in a chaparral landscape. Because there are few trees, “removing the underbrush” does not seem practical because most vegetation in the area is underbrush. Some people argue that fuel reduction and prescribed fire should not be used in chaparral-covered hillsides in California in the same way that fuel reduction is used in forests. Riverside and Los Angeles

Riverside and Los Angeles

Chaparral Urban Area

Chaparral Urban Area

On the other hand, Riverside County, also an urban area within a chaparral biome, had the largest amount of documented prescribed fire and fuel management acreage and the fewest acres burned from wildfire within the 7 counties we looked at. Santa Barbara had over 14x more acreage burned than Riverside, indicating that despite the ecological controversy, it may have been successful. Los Angeles, also a largely urban area documented no prescribed fire acres, but documented 4,712 acres of fuel management. There were in fact far more acres burned by wildfire in LA County compared to Riverside despite their close proximity. This may be due to prescribed fires in Riverside, and the lack there of in LA.

Kern

Desert, Chaparral and Conifer Forest

Desert, Chaparral and Conifer Forest

Kern County is further east than the two previous counties. Within Kern County, there is the Mojave Desert, chaparral, and some conifer forests. The desert biome is particularly prone to fires caused by lightning. Because there is little vegetation in the eastern half, it is reasonable that Kern County didn’t have any documented acres of prescribed fire.

Nevada-Yuba

Grasslands, Oak Woodlands, and Conifer Forests

Grasslands, Oak Woodlands, and Conifer Forests

Nevada-Yuba, located in Northern California, is composed of much different vegetation than what is often found in the south. Some Scientists claim that ecosystems with grasslands, oak woodlands, and conifer forests can more effectively clear overgrown fuel in the underbrush compared to chaparral biomes. Nevada-Yuba documented the most prescribed fire acres (6,841 acres) and the fourth most fuel management acres (3,721 acres) in the 7 counties we compared. Our hypothesis expected Nevada-Yuba to have a comparatively small amount of acres burned from wildfires, however it had the 3rd highest amount. I would speculate that Nevada-Yuba may not focus so heavily on suppression and allows the natural fire regime to occur.

Tulare

Desert, Chaparral, Conifer and Juniper Forests

Desert, Chaparral, Conifer and Juniper Forests

Tulare County, located above Kern County, had a very small amount of prescribed fire acres and fuel management acres, at 292 and 176 respectively. Tulare has a very diverse vegetation with a small portion in the Mojave Desert, along with some chaparral, conifer and juniper forests. With the presence of juniper and chaparral, fuel management practices may be difficult due to the homogeneity in the height of the trees. People may be reluctant to invest resources into fuel management when prescribed burns or fuel removal might damage the natural ecosystem of the shorter shrubbery with little underbrush. Despite the lack of documented acreage of prescribed fire and fuel management, Tulare had the second smallest acreage of burns from wildfire.

Shasta

Conifer Forests

Conifer Forests

Shasta County, located in the uppermost section of California, is mainly dominated with Conifer forests. Shasta was the outlier in our data with a strikingly large amount of total acres burned by wildfire at 277,884 acres–over 55 times more acreage than the next highest at 5,017 in Kern County. This figure is from the massive Carr Fire that occurred in August, that spanned across both Shasta and Trinity Counties. Despite this being an anomaly in the data, Shasta County had less than 1,400 combined acres of prescribed fires and fuel management. Because this county is largely dominated with conifer forests, there is no reason why fuel management practices were sparse.

Conclusion

Wildfires are bound to happen in California. My original belief, that Southern California has used excessive suppression techniques, has now shifted after looking at the data in terms of location. Our original thought was that fire suppression was disrupting natural fire regimes. And while this very well may be true, we must separate many more factors out of the equation to validate this conclusion. This may be true in northern counties with large portions of conifer forests, but southern counties are limited in their ability to practice fuel management because of their vegetation makeup. The data presented in the R analysis shows to be inconclusive, however some anomalies in these graphs seem to explain these anomalies.

In the future, if this test were to be redone, scientists should compare data in counties in close proximity. The inconsistency in the cdf Strategic Fire Plans throughout counties shows that that fuel management practices are locally specific. I do believe however comparing these data would be made much easier if each county was accountable for updating data on fuel management techniques. A centralized website to find these data is a good way for researchers to understand what techniques are working and which aren’t. A centralized website also ensures that researchers are not accidentally double counting fires because he or she needed to reference multiple.

In looking again at the three null hypothesis, we can state with reasonable certainty that fuel management techniques and prescribed burning help to reduce total acreage burned. The total number of fires, in contrast, does not seem to have a correlation with total acreage burned. It may help, however, with reducing the duration, intensity, and heat of fires.

California’s wildfire epidemic is highly involved with location based policies. Understanding how and why fuel management should be utilized will help California restore natural fire regimes as well as improve safety for California residents.

References

References: “Biomes of California.” Home, civilizedape.weebly.com/biomes-of-california.html. California, State of. “California Statewide Maps.” CAL FIRE - Home, www.fire.ca.gov/current_incidents/?page=19. California, State of. “Fire Plans.” Fire Statistics, cdfdata.fire.ca.gov/fire_er/fpp_planning_plans. Cart, Julie. “California Fights Wildfires Aggressively-but Prevention Takes a Back Seat | CALmatters.” Google Search, Google, Mar. 2018, www.google.com/amp/s/calmatters.org/articles/california-fights-wildfires-aggressively-but-prevention-takes-a-back-seat/amp/. Halsey, Richard. Escaped Cal Fire Prescribed Burn San Felipe Valley Wildlife Area. 2013, Escaped Cal Fire Prescribed Burn San Felipe Valley Wildlife Area.