It feels like everybody's Instagram feed is currently covered in springtime photos, especially in Southern California, where a wildflower bloom caused by record-breaking rainfall has caused blooms to sprout from seemingly every patch of dirt, from the neighborhood sidewalk to the desert. But in some areas the blooms have been further stimulated by last fall's wildfires, and I wanted to talk to some scientists about how those fires might be impacting the local plant life. Biologists Mark Mendelsohn and Richard Rachman were kind enough to let me join a media hike at the Santa Monica Mountains National Recreation Area to learn more about the recent wildfire blooms and find out how the National Park Service monitors the effects of the fires on the local ecosystem. The day started with a hike to take a look at the plants that had already started to regrow in the area around Paramount Ranch. This area was part of the area burned in the devastating Woolsey Fire in November of 2018. But both native and non-native plants and shrubs had already started to regrow. Some of these wildflowers are considered to be fire followers.

(Describer) Mark Mendelsohn.

A fire follower is a type of plant that is encouraged by fire, so it either increases in abundance or, in some cases, it only comes up following fire.

(describer) Flower names appear--

(Describer) Flower names appear. Title: Blue Dicks.

title: Blue Dicks.

(Mendelsohn) And so it usually has

(Describer) Title: Phacelia hubbyi.

characteristics to its seed where heat...

(describer) Title: Catalina Mariposa Lily.

(Describer) Title: Calochortus catalinae. Catalina Mariposa Lily

(Mendelsohn) ...or smoke or the chemical residue from the fire...

(describer) Title: Arroyo Lupin.

(Describer) Title: Arroyo Lupin.

(Mendelsohn) ...caused the seed to germinate. This is owl's clover, a lovely native fire-following species. At one point, the hike turned into a little bit of a treasure hunt as we noticed some rare plants growing along the trail, and there's little that I love more than scientists excited about the species that they work with.

(Describer) Subtitles: "Oh, there's a globe lily!" "Right here!" "Yeah, nice!"

(Mendelsohn) Oh, there's a globe lily.

(speaker) Right here. Yeah. Yeah, nice.

[woman claps, laughs]

(Describer) "Awesome!"

Awesome. This is another type of mariposa lily.

(speaker) A globe lily.

(Mendelsohn) But this we call fairy lantern or globe lily. And then this light-flowering phacelia

(Describer) Parry's phacelia.

is actually the same species as this Parry's phacelia here. It just happened to have a white morph here. Mark and Richard also showed us some other important native species that have started to regrow or resprout after the fire.

(Mendelsohn) This here, this is yucca, or also called Our Lord's candle-- our first species to resprout following the fire, and only about three weeks following the fire, before the rains even came. You look at this and, you know, the casual observer would say, "Okay, well, that's neat. "The fire scorched this leaf, you know, right here and it left the rest of these just like that." But what actually happened was that this--

(describer) Where the white part of the leaf meets the green--

(Describer) Where the white part of the leaf meets the green.

(Mendelsohn) --this point right here, this line was all the way down there at the base, and all of this growth has happened since the fire. So it's a quick-growing species. One of the main components of our chaparral here, chamise, also called greasewood, is very flammable. If you look down at the base of the plant, you can see many, many green sprouts that are about six inches coming up from the base. The energy is stored down in the base of the plant. While the flowers that we saw were beautiful, and while the fires played a role in their appearance, it's really not good for the local ecosystem that these fires are happening so frequently. One of the fears surrounding these fires is that if they happen too often, something known as type conversion could happen where two frequent fires disrupt the normal growth cycles of the local ecosystem, causing the type and diversity of plants in the landscape to change. The normal fire regime of this area is every 50 to 200 years, and we're getting fire way more frequently than that. And our native vegetation types didn't evolve with that. So you can have chaparral, for example, changing into coastal sage scrub and then coastal sage scrub turning into-- into non-native annual grassland. So that process is called type conversion, and that's a concern. In general, it's a concern ecologically, but for the National Park Service, part of our mission is to preserve-- preserve the natural resources in their state. So we are concerned with human-induced changes to the natural resources. It's too early to say whether we have type conversion following this fire. We need probably a couple of years of data to tell us for sure, but so far we see a strong resprouting and recruitment of our shrubs. We headed out to a vegetation monitoring plot where Mark and Richard collected data that will be used to see if these types of changes in species' diversity and richness are happening in response to the fires. So we have about 300 randomly located plots around the Santa Monica Mountains. And we are visiting-- we normally visit 100 a year, but because of the fire, we have to visit 215. So we have to visit all the plots that burned. So we have our work cut out for us.

(host) We navigated to the plot site where Mark and Richard established a 30-meter transect line along which they would monitor species' richness and diversity. This would also become the first side of a 300-square-meter rectangle that would be further surveyed.

(Mendelsohn) And we're going to lay out a 30-meter measuring tape and we're gonna record some data-- actually a lot of data alongside it. we're gonna record things like which species are present, how tall the vegetation is, what the burn severity of the plot is and whether any shrubs are coming up. We'll go for the first two years following the fire, and then plots get rested for four years. It means they get time to recover from us trampling a little bit in collecting our data. And then we go out for the-- in the two years in a row again, and then rest it for four years, then back for two years. So this is called our transect establishment/revisit form.

(host) Okay. And and this is basically the first time we come to a plot, we have to write down a bunch of information about it so that we know where it is, how to get there, and that's-- and what it looks like. We're gonna record-- We're gonna put a bunch of species' names here and their six-letter codes.

(host) Okay. And then wherever they exist along the tape-- this is from 0 to 30-- we're gonna do a little check. We break it into five-meter segments, and then, additionally, the first meter of each five-meter segments gets recorded separately, and that's so that we can compare our species' richness data to other studies around the world that measure species' richness within 1 square meter, 5 square meters, 30 square meters, 100 square meters, 300 square meters. Okay.

(Describer) Richard Rachman

We will get the species' diversity that's in there. So every single flowering plant species and sometimes flowering plant ally, like ferns... Okay. 'cause they're not flowering plants, but we would count them as well. Once the plot was established, Mark and Richard moved their way down the transect line tape meter by meter, carefully recording every species present. Phacelia hubbyi.

(Describer) Richard records Mark's observations.

Phacelia viscida. Acola mar. Lup suc. Yeah, there's Apiastrum angustifolium. All right, so eucrypta is here,

so that means that-- [indistinct]

Yeah, but I think it's also right here. Getting the distinct species correct while monitoring is important. And while they were easily able to identify a lot of plants, I also watched Mark and Richard examine tiny hairs on leaves or measure portions of grasses to make sure they were recording just the right species.

(Mendelsohn) The Southern Californian Mediterranean-type ecosystem is one of the most species-diverse areas on the planet. Our flora has, I think, some 700 or 800 plants here in the Santa Monica Mountains. Once finished with those measurements, they would move on to monitoring the larger plot, allowing them to gather data that would let them observe year after year what kinds of plants were returning after the fire, keeping an eye out for possible type conversion. The landscape of the Santa Monica Mountains is... can be resilient to fire. It can recover well from fire, but that depends on getting the right amount of rain and it depends on the fire return interval, which is that how frequently we get fire. So, yeah. This can be... naturally our landscapes are resilient to fire, and they can recover well and look as beautiful as, you know, this does and the landscapes we visited elsewhere today. But if we get too much fire, we are interrupting the natural succession. A huge thank you to Mark and Richard and the Santa Monica Mountains National Recreation Area for welcoming me into the field for a day. I really appreciated it. A thank you to my Patreon patrons for supporting this type of content, and a thank you to you for watching. And, as always, remember to go forth and do science.