That’s a good question and I’m sorry you had to experience the 2020 fires in Canberra. I hope you and your family are ok. I’m not a wildland firefighter, but I’m aware that the truly catastrophic fires that some areas have experienced in recent years have outpaced fire management organizations and capacity. Unfortunately, studies and models suggest that with a continually warming climate and decades of successful fire suppression in many areas, wildfires will continue to threaten many communities. Prescribed fire, mechanical fuel reduction, and limiting flammable vegetation close to buildings in wildland urban interface areas can help reduce the frequency and intensity of wildfires.

Other efforts to increase community and homeowner resilience are going to be important. Research has shown that in many cases structures ignite from wind blown embers. There are many resources that provide recommendations for home hardening, another activity that can help reduce the impact of risks like that: https://wildfirerisk.org/reduce-risk/home-hardening/

The longleaf pine ecosystem, for sure! In North America, it is known to have the highest natural fire frequency. This is supported by the fire-scar record along with other lines of evidence like its high lightning activity and flammable vegetation type. Ponderosa pine also comes to mind, although fires in that ecosystem type weren’t quite as frequent and varied a lot with elevation.

I had only planned to answer questions until 1:00PM ET but it's been so fun answering all of your great questions that I had to keep going! It is actually time to hop off of here for now, though. I might have time later to return to some questions that I missed.

Thank you to everyone that joined today, and for all your great questions about fire ecology, dendrochronology, and wildland fire! If this has sparked your curiosity, and you have more questions, visit my website, (https://sites.google.com/view/monicarother/home), the Southern Fire Exchange (https://southernfireexchange.org), or any of the Joint Fire Science Program supported nationwide Fire Science Exchange Networks (https://www.firescience.gov/JFSP_exchanges.cfm).

From the fire-scar perspective, the earliest evidence dates back over 200 million years ago! Check out this article about a fossilized chunk of wood with an obvious fire scar!

https://www.livescience.com/47316-oldest-forest-fire-scar-fossil.html

I am currently funded by various sources including the National Science Foundation and the North Carolina Collaboratory. I also sometimes go for small, internal awards (through my university) that support research. Additionally, I sometimes work with land management agencies to make agreements/contracts for work.

I’m not sure I understand your question in terms of what you mean by a pathway to independence…can you explain more?

There are many hardwood species in the South that could be considered fire tolerant. Some of them are considered pyrophytic, meaning that they have flammable characteristics (flammable leaf litter) and adaptive strategies for protection or recovery from fire (thick bark, ability to resprout). There are some fire-scar studies in oaks! Mike Stambaugh comes to mind as one researcher who has done some fire-scar work in oaks - see: https://treerings.missouri.edu/publications/ That said, some oaks have challenging tree rings to work with or do not scar as frequently as some of the pines we use for this research.

I'll copy my response from a similar question that was asked below!

>Great question! I think a recent study that I completed with colleagues in the Red Hills Region of Florida and Georgia was especially fascinating. Most tree-ring based fire history studies show almost no fire activity in the 1900s and later. This is because of the “Smokey Bear Effect” - people stopped allowing fires to burn in the U.S. through direct fire suppression. There were also changes in fuels related to development (e.g., roads that disrupted fire spread) and cattle and sheep grazing that inhibited fire occurrence and spread in much of the U.S. What was interesting about the Red Hills study is that we found TONS of fire activity through the 1900s and up to the present day. The Red Hills have long been known as a region where the burning never stopped, but we provided hard evidence of this claim through the fire scars.
>
>Here’s a link to that publication:
>
>https://www.sciencedirect.com/science/article/pii/S0378112720311750

Absolutely! There are so many so I can’t be comprehensive in my answer, but here are some suggestions of researchers who work with PhD students!

Rae Crandall, University of Florida

• Grant Harley, University of Idaho
• Scott Stephens, University of California Berkeley
• Don Falk, University of Arizona
• Rosemary Sherriff, Humboldt
• Max Moritz, UCSB
• Heather Alexander, Auburn University
• Mike Chamberlain, University of Georgia
• Marcus Lashley, University of Florida
• Mike Stambaugh, University of Missouri

Good question! There are many people who are trying to understand how to significantly increase the pace and scale of prescribed burning in the US. The National Association of State Foresters publishes a regularly updated report on the use of prescribed fire across the US. In the 2021 report that was just recently published (https://www.stateforesters.org/wp-content/uploads/2023/01/2021-National-Rx-Fire-Use-Report_FINAL.pdf) they identified nine impediments to the use of prescribed fire: capacity, weather, air quality / smoke management, resource/funding, public perceptions, liability/insurance, permitting/legal concerns, WUI/population growth and agency/landowner priorities. The report provides a bit more information about each of these categories, but it’s likely that limitations vary by region and locality.

Prescribed burning is extremely beneficial and there is no perfect replacement. The ecosystems we burn with prescribed fire evolved with fire and require frequent fire to maintain healthy conditions. Additionally, the prescribed fires can actually help protect people! First, the prescribed fires reduce fuels (living and dead plants) and decrease the likelihood of a much more dangerous, unplanned wildfire. Second, less smoke is produced by a prescribed fire than a wildfire and this smoke can be managed through strategic burning to minimize smoke to sensitive areas like surrounding communities. Alternatives to burning (like mowing down vegetation or using herbivores) can be beneficial in certain areas where prescribed fires aren’t feasible, but they do not perform the exact same roles as fire performs on the landscape.

Good question! Fire severity is a great way of attempting to quantify the variable impacts of fire. From a remote sensing perspective (typically satellite), there are multiple techniques that have been developed to identify and map patterns of post-fire burn severity. Many of these techniques use multispectral satellite sensors. The normalized burn ratio (NBR) and its variations (dNBR) come to mind. There is even a national (US) archive of burn severity maps available for free online from the Monitoring Trends in Burn Severity (MTBS) project led by the USGS (https://www.mtbs.gov/). For assessing burn severity from the ground, you might consider looking into a technique called the Composite Burn Index (CBI). Link for more info here: https://burnseverity.cr.usgs.gov/products/cbi.

>Great question! Yes, there is some evidence that forests are recovering more slowly (or not at all) after fire. We see a lot of this research coming out of the western U.S. For example, for my dissertation work, my colleagues and I documented very limited tree regeneration after wildfires in ponderosa pine woodlands in the Colorado Front Range. I’ve also been involved in several larger studies (meta-analyses) that combine data from different areas to show that this problem isn’t isolated and is a major one across many western landscapes. This research has successfully shown that changes in climate are at least partly to blame - hotter, drier conditions after fire can make it much harder for tree seedlings to germinate and survive. Changes in fire severity (also related to climate change) can also create challenges for forest recovery. For example, ponderosa pine only disperses its seeds short distances, so if a large, severe fire kills all the mature pines in an area, recovery can be very slow.

We see a lot of variation in historical fire regimes in terms of the fire frequency and intensity. In some places, the fire history might show a fire frequency of every 1-5 years. In other landscapes, the natural fire regime might show fires occurring every 10-20 years. Longleaf pine ecosystems have the highest natural fire frequency. An important thing to remember with the fire scar research is that we can only use fire scars when fires are relatively low in intensity and the trees survive. Some forests in North America are meant to only burn at high severity very rarely (e.g., every century), but it’s much harder to use fire scars in these systems; only around the fire edges where some trees might have survived. If you’re interested in fire frequency in the US, check out the PC2FM model of predicted potential natural fire return intervals based on physical chemistry factors alone (https://oakfirescience.com/research-brief/predicting-fire-frequency-with-chemistry-and-climate/). It’s a fascinating model that uses only physical factors to predict how much fire our landscapes might sustain. This model doesn't even include anthropogenic ignitions, which we know are and have been truly significant in many landscapes!

I have a lot of experience with prescribed fire but no experience fighting wildfires! Of course the wildfire environment tends to be much more challenging and unpredictable. Fortunately for me, I haven’t experienced anything too sketchy/terrifying in my experience with prescribed fire. I have experienced spotting (on many burns!) where a bit of fire goes outside the boundaries of the prescribed fire. This is a bit nerve wracking but we are always prepared with water and tools (shovels, rakes, etc.) to put out these fires before they get out of hand. I have found that good communication and keeping calm are the two most important things to managing challenging situations like these - talk to the team, make a plan, and keep your head calm and collected! And make sure to be ready for changes in the weather/fire conditions!

Great question! As with many questions in ecology, it depends. The impact of fires on ecosystem soils tend to depend on the amount of soil heating that occurs, the amount and duration of vegetative cover lost, and the post-fire events that follow. Soils tend to be remarkably good insulators, and in many cases, elevated temperatures due to fire may only go a few inches underground. Because of that, low intensity fires often have minimal impacts on soils. On the other hand, high intensity fires or fires with heavy fuels concentrated on the surface and with long residence times, can have more significant impacts to the soils. In some cases directly volatilizing soil organic matter and soil nitrogen. As we see in more arid places in the western US, post-fire erosion can be a huge issue due to pre-fire heavy fuel loads and post-burn soil exposure due to delayed vegetative response. In the southeastern US, ecosystem vegetation can respond within days of a fire, protecting the soils from erosion. In more arid places, vegetation may not recover for months, leaving the soils exposed to erosion.

In my own research, I do not sample live trees for fire history. Because fire scars can occur on any side of a tree, we generally need a full cross section (sometimes called a tree cookie) for the fire-history work. We focus on collecting these cross sections from snags (standing dead trees) and stumps. There is a tree-ring method of sampling live trees without them - a pencil thin core is extracted using a tool known as an increment borer. However, this method is not useful for fire history; it’s used in studies that examine things like tree age and climate-growth relationships. You can check out cool photographs of working with stumps and live trees on my research website:

https://sites.google.com/view/monicarother/photo-gallery

Thanks for the question! Fire in California is very different from fire in the Southeastern U.S. (where I am based). It’s a combination of many factors that makes the wildfire situation so challenging out there. First, the climate (including the winds but also the hot, dry summers) is very conducive to fire. Second, the topography is complex and the mountainous landscapes also create a more challenging situation for controlling fire. And yes, human ignitions are a huge problem in California and across the globe - not just by ‘miscreants’ but also through accidental ignition related to vehicles, power lines, and other issues. Another thought is that we also have a ‘fire deficit’ in many landscapes - fires have been suppressed for decades or longer in many areas which creates a more flammable situation that is more vulnerable to burning at higher intensity. Finally, it’s also important to remember that fires are indeed natural in many Californian landscapes - so just because it’s a wildfire that may create challenges/hazards for people doesn’t mean it is totally unnatural and isn’t providing any ecological benefits.

So far in my research, I have focused on two different pine species. First, in the Southeast, I have worked with longleaf pine (Pinus palustris). This species used to be widely distributed across the North American Coastal Plain, from eastern Texas up to southeastern Virginia. Longleaf pine and its associated ecosystems are fire maintained - they need very frequent fire (about every 1-4 years) to stay healthy! In the West, I have worked with ponderosa pine (Pinus ponderosa). Like longleaf, ponderosa is known to require frequent fire to maintain healthy forest composition and structure. I’m in love with these two fire-adapted pines!

That’s a great question! With the understanding that in many places there is a fire deficit on the landscape, there is quite a bit of interest right now in cultural burning across the US / globe. Tree rings and fire scars don’t specifically provide information about how the fires were started, but inferences can be made in some cases. My work into understanding the seasonal aspects of fire scars can help to provide clues about the origins of fires. When we see fire scars that indicate the tree scarring occurred outside of typical wildfire season(s), we can often make assumptions that those fires were anthropogenic in origin. We consider burning by indigenous people to be an important part of the historical fire regime in many locations.

Great question! I think a recent study that I completed with colleagues in the Red Hills Region of Florida and Georgia was especially fascinating. Most tree-ring based fire history studies show almost no fire activity in the 1900s and later. This is because of the “Smokey Bear Effect” - people stopped allowing fires to burn in the U.S. through direct fire suppression. There were also changes in fuels related to development (e.g., roads that disrupted fire spread) and cattle and sheep grazing that inhibited fire occurrence and spread in much of the U.S. What was interesting about the Red Hills study is that we found TONS of fire activity through the 1900s and up to the present day. The Red Hills have long been known as a region where the burning never stopped, but we provided hard evidence of this claim through the fire scars.

Here’s a link to that publication:

https://www.sciencedirect.com/science/article/pii/S0378112720311750

That’s exciting that you have initiated a PhD on wildfire! Congrats! This is a tough question because it just depends on where you look! In longleaf pine ecosystems of the Southeast, for example, our tree-ring records show us that we need more fire on the landscape. We need to continue our prescribed burning and increase it in many areas. There are some locations where fire activity has changed in recent years, related to climate change and the history of fire exclusion (including fire suppression). In some places, fires are happening more frequently than historically, based on comparisons to the tree rings and other proxy records.

Yes, we do have some general rules in terms of the number of trees needed for a fire history study using tree rings. For each site, we tend to want at least 10-15 trees. However, there is some wiggle room there since it depends on whether the trees we sample have picked up on a lot of fire activity or not. Some trees are better than others at documenting the fires that occur around their bases. In some studies, I’ve seen 20-40 trees included per site.

I’m not sure about faking tree rings, but there have been studies that have intentionally created fire scars (damaged tree tissue caused by fire). These studies have looked to understand the mechanisms and conditions under which fire scars can be formed and thus under what circumstances trees record the occurrences of fire on the landscape.

Yes! Many plants that have evolved with fire have traits that make them more flammable! For example, the long needles of longleaf pine are very flammable - their chemistry makes them more likely to ignite and burn. And the way they land on the understory creates a nice continuous layer of fuel that also allows oxygen to get in (a needed ingredient of fire). There are also fire-loving oaks that have flammability traits that encourage fire. The Mutch Hypothesis captures a lot of these ideas. We are still learning about the many fire traits that plants can have but we definitely see that our fire loving plants tend to encourage fire!

Sure! You can get my email address from my website here: https://sites.google.com/view/monicarother/home