When you’re working on a PhD, you spend a lot of time focused on one topic. I’ve managed to broaden my work a bit to suit my interests–some of my research is plant-focused evolutionary ecology, some is a foray into social science, but for the most part all of the projects are about wildfire. Grad students are encouraged to keep their eyes on the prize: completing the dissertation and the PhD and building a career. So when the opportunity came up to take Lichenology this past quarter, I was conflicted. I knew little of lichens, other than that they were symbiotic arrangement between a fungus and a photosynthetic partner and that they grew on trees and rocks. But I’m a sucker for learning something cool that few people know much about. The instructor was a new postdoc friend with infectious enthusiasm. On the other hand, I also want to graduate next year, and I’m trying to be better at saying “no” to things–even the cool things.
But I had a very smart professor in college, who taught mammalogy and conservation biology. He taught ecology via the Socratic method, made us get up and move our limbs around to understand how mammals and reptiles moved differently, took us on camping trips, and peppered his lectures with life lessons about science. One day he told us a story–here’s how I remember it: Anthropologists working in a museum were puzzled by some primate skulls in a pit, with two holes on each skull. Was this some kind of strange burial ritual? Two floors up, mammalogists were studying big cats, but the two departments didn’t interact often. Finally, they happened to discuss their work, leading to the hypothesis that a large cat was biting the heads off the primates and due to the topography of the area, the skulls dropped and rolled into the pit. Now, I’ve tried to figure out where this story came from in the years since. Maybe I have the details wrong, maybe it was just an allegory. But the moral of the story stuck with me: talk to people outside of your study area, your department, your field–venture out and you may get some new insight into what you’ve been studying all along.
So now, five years into my PhD, with an ever growing to-do list, I said to hell with it and took Lichenology. And it was fantastic. Each week this spring, I learned things that were completely new. I learned the parts of a lichen, the different growth forms, the messiness of lichen taxonomy, the improbability of lichen sexual reproduction, how birds and insects and humans use lichens, how to collect a lichen, key it out, take a slice of an apothecium to reveal its tiny spores under the microscope. It was refreshing. I became part of a special new club of the enlichened.
Of course, I was still on a day to day basis part of the fire ecology club. So it was natural that I do a final project for lichenology related to wildfire in chaparral. There’s not a lot of research out there about lichens and wildfire or lichens in chaparral, but relative to something like plants, there’s just not a lot of lichen stuff at all. That can be frustrating–but it’s also exciting. Working on a PhD means trying to come up with an original idea, and most of us find at one point or another, years into the process, that someone is doing or has done something strikingly close to what we are doing, and somehow you missed that paper. With lichens, there is so much uncharted territory.
But the thing about lichens is that they’ve been there all along, even when we don’t think to notice them. They tell new stories and the same stories about our home ecosystems all at once. Hanging out on trees or rocks or shrubs or soils–they can reveal hidden truths about our environments or reflect the patterns that we’ve long seen.
And so it went with the lichens of chaparral. My reading on chaparral lichens brought me quite quickly to familiar systems: The Santa Monica Mountains and Santa Cruz Island. Though lichens have been collected from a variety of places that include chaparral vegetation, the most complete survey of a chaparral-dominated region and discussion of lichen diversity in this particular system comes from work in the Santa Monicas. A lichenologist by the name of Hasse built an extensive lichen collection in the region in the late 1800s. A century later, Kerry Knudsen, coming to lichenology as a second career, took on the task of cataloging the modern state of lichens of this region–the Santa Monicas, the Channel Islands, and other parts of Southern California (see a terrific article on Knudsen and his explorations of Santa Cruz Island here).
In these writings about lichens there is a familiar story to fire ecologists, especially those who have studied chaparral. Here’s the argument: lichen diversity has declined significantly in the SMMs due to shortening fire return intervals over the past century, a change driven almost exclusively by human population growth and one that stands in contrast to Sierra forests, where fire intervals have lengthened due to fire suppression. The Santa Monica Mountains, just north of Los Angeles, have exemplified this change and perhaps experienced some of the greatest shifts in fire frequencies (the SMMs are also where research focused on the grass-fire cycle, where frequent fires drive a shift from chaparral to non-native grassland, in turn further reducing fire intervals). In contrast, lichen diversity on isolated Santa Cruz Island is excellent–fires are rare out there.
In my own research, I have used this very comparison–I have spent long hours of fieldwork in the Santa Monicas and on Santa Cruz Island studying big pod ceanothus (Ceanothus megacarpus) and its response to the island-mainland contrast in fire intervals. The lichens living the same dynamic had never caught my eye before.
Given my background reading, I set out to see if I could provide any insight at all to this discussion by searching for lichens in the chaparral at Stebbins Cold Canyon Reserve, our local reserve that burned at high severity in 2015 (link to other blog posts). My survey was quick and casual–less than a pilot study, even–but I had novelty on my side (and, perhaps, against me). Because, you see, not only is there little work on lichens and fire and chaparral–there’s relatively little research about chaparral in Northern California at all. Most of the time, chaparral is synonymous with Southern California. It’s true that chaparral covers more area in the South. Further north, the attention goes to the forests, and the huge stretches of chaparral that cover the Coast Ranges and the Sierra foothills get less attention, even though some of the largest fires in the northern part of the state burned through chaparral, such as the 70,000 acre Rocky Fire of 2015 in Lake County. As in Southern California, fires in the chaparral here are almost exclusively human-caused and appear to be more frequent than they once were, though the data on this are not as good as in Southern California.
So there I was, off to study lichens in the chaparral of Northern California. My survey took me up to the top of the ridge at Stebbins Cold Canyon, first through a section where the ridge top path was burned severely on both sides and then where the path served as a boundary between burned and unburned. For the first part of the trail, the number of lichens was approximately zero. Expanses of chamise skeletons, nearly all perfectly black and devoid of lichens, survivors or colonizers. In a 5 mile walk (not all of it chaparral-dominated), I found one tiny yellow Candelaria on a charred skeleton. Any other lichens in the burn perimeter were shrubs that burned at lower severity or not at all (sometimes in rocky fire refuges) or on rocks. It was easy to see how too much fire could threaten lichen diversity.
But across the path, so close to the fire but unburned for 28 years, I found hints of the high lichen diversity of so-called old-growth chaparral. These shrubs, mostly chamise but also toyon, manzanita, ceanothus, and scrub oak, were not quite so old to be dubbed “old-growth,” but many had at least 10 species of macrolichens easily identifiable to my eye on two months of lichen training. How long did it take them to grow there? Would there be many more yet if that patch survived another decade or two? What even were the odds that it would remain unburned another decade or two? There have been fires very close by every year for the past four years, bordering one another, burning some patches of land twice over.
The land here is adapted to dramatic change, we say. Chaparral is a fire-prone landscape, and always has been, we say. This is true. But just as the climate is changing faster than ever, the fire clock in chaparral moves more quickly now, as more and more of us live and play in this land, and as our hottest days become hotter. And the lichens that make up the background of our most loved places, whether we see them or not, are shaped by accelerating change alongside the tall trees and furry felines. Don’t forget to shift your focus every now and then.