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Bryan Vejar

Bryan Vejar

Caltech Arborist

By David Zierler
September 7, 2022

DAVID ZIERLER: Ok, this is David Zierler, Director of the Caltech Heritage Project. It's Wednesday, September 7th, 2022. I'm delighted to be here with Bryan Vejar. Bryan, it's great to be with you. Thank you for joining me today.

BRYAN VEJAR: Thanks for having me, David.

ZIERLER: Bryan, to start, would you tell me your title here at Caltech?

VEJAR: I am the Campus Arborist here at Caltech.

ZIERLER: Now, do you have a sense, does that title precede you? Have there been arborists in the past or are you the first?

VEJAR: The job title when I was hired was tree care specialist, and so that didn't necessarily mean that there were certified arborists in my position before. In fact, as far as I know, there were certified tree workers and just very experienced tree workers in my role before I joined Caltech. But, currently, I am an ISA Certified Arborist and a Tree Risk Assessor and, to my knowledge, I'm the first one in my role to have both of those titles.

ZIERLER: Bryan, tell me a little bit about the education, what it takes to get certified in this field?

VEJAR: Well, I'm certified through the ISA, which is the International Society of Arboriculture. That organization is an international organization that certifies arborists worldwide. In order to become an ISA certified arborist, you need to demonstrate a comprehensive knowledge of all manners of the industry, whether it's planting, tree diagnosis, tree healthcare, climbing, appraisal, soil science, and soil hydrology. Basically, everything having to do with trees, you have to demonstrate a comprehensive knowledge on. You also have to meet a minimum amount of years to even qualify to apply for the exam. Once you take the exam, and pass the exam, in order to remain certified, you have to continuously take CEUs, which are Continuing Education Units, in order to remain certified.

ZIERLER: Bryan, I'll ask a general question about Southern California, and then a specific one to campus. I'm from the East Coast. It rains at the East Coast. Our trees need rain. I come here. Pasadena, Los Angeles generally, it's green and, yet, there's no rain. I don't get it. What's going on? Can you please explain this for me?

VEJAR: What's going on is a tremendous amount of effort and planning in order to support our urban forest. Something you'll notice on campus, and perhaps you'll notice more broadly in more, let's say, affluent neighborhoods is that they have a robust and developed tree canopy. This is for a variety of reasons, and we can get into that later. But we on campus have allocated a lot of resources to developing healthy and large trees, and some communities that have the resources to support and fund an urban forestry department can do the same. Unfortunately, there is historically a lot of communities and cities and neighborhoods that don't have as robust a set of resources in order to support an urban forest. Circling back to your question, it takes a lot of work, it takes a lot of planning, and it certainly takes a lot of water [laugh] too. It's something that is growing more and more precious every year.

ZIERLER: Now, I'll ask that question specific to campus. Here we are in the middle of what seems like a record-breaking drought. What's important to you both in terms of keeping our campus green but also operating within the spirit of sustainability?

VEJAR: That is a tightrope that we are continuously trying to walk. First I'll say—and perhaps I might be biased—but our trees are critical infrastructure. Trees are generally overlooked. They're ornamental. They're cosmetic. Often, when budget cuts happen, they're sometimes the first things to be cut out of the budget because, again, they're not seen as essential. I would contend quite the opposite. In fact, in order to create a both physically and also socially and mentally healthy environment, we need to have a well-developed canopy. Trees do so much for us, not just physically but also mentally, as I said. They cool us down, especially in the heat of the summer. They transpire water, further cooling the immediate air around us. They are super important for us to allocate resources toward. The issue right now with sustainability is that having faced these water restrictions on campus because of the drought, we're having to shut off or limit severely our landscape watering. The problem is that many of our trees are located in those turf areas, and are either in part or directly watered by that turf water, that turf irrigation, I should say. When you cut off the water to what's deemed as nonessential turf, you're also severely limiting the resources for the trees that are planted in that turf. Trees, as you know, they take generations to accumulate in value to create larger—in fact, they're probably the only piece of infrastructure that does gain in value as it ages. [laugh] Again, circling back to your question, it is a bit of a tightrope to try and conserve water as much as possible while still trying to retain that value that we have in our ecosystem, our little mini biome here on campus.

ZIERLER: I'll ask a question in the way of, if you had a blank canvas that you were working with, there were no trees on campus, would you go all native at this point? Would that make your life easier? Would that make the most sense, or is there something to be said for having non-native species for all of the benefits that they confer?

VEJAR: [laugh] I absolutely love this question. This is actually a very contentious issue in our industry right now. I started off my career as a native landscaper, taking out turf, taking out non-natives, and planting California natives. Doing that and volunteering at the California Botanic Garden, which was once called the Rancho Santa Ana Botanic Garden, which specialize in California natives, I sort of became radicalized, and I was like a bit of a zealot for California native plantings. Since developing my career, and gaining experience in the field, and getting experience in working in urban environments, I've come around completely on this issue. The truth is there are a lot of purists in our industry who have their heart in the right place and say, like, we only need to plant natives here in our neighborhoods, in our communities. The problem is that, well, there's a number of problems, and I'll go through them. Number one, our environment isn't native any longer. Our urban environment is filled with structures, utility lines, impermeable surfaces. Our neighborhoods are not the same kind of microclimate that trees that preceded us here were growing in. Furthermore, we don't live in a natural forested area. There's only a small handful of native shade trees that existed here before we were here.

As an urban planner, as a city forester, as an urban forester, actually, I should say, it's really critically important that you maintain a certain amount of biodiversity in your urban forest. This is because if you only planted five or so native species here—which would, in effect, be a monoculture—you'd essentially be inviting infestations of pests, both native and non-native, to completely wipe out your ecosystem. We observe what's called a 10, 20, 30 rule in our urban forest, which is no more than 10% of one species, no more than 20% of one genus, and no more than 30% of one family in any given urban forest. I think that native plantings should—and need, actually—to play a critical if not central role in our urban forests to be something of little oases for our native pollinators and our native plants and our native insects and other wildlife, but they can't be the only answer in our urban forest.

ZIERLER: Are you dealing with water restrictions on campus? Is there a certain amount of cubic meters, or whatever the measurement is, that you have to stay within?

VEJAR: Oh, boy, are we. I couldn't give you the hard numbers of the certain amount of foot acres of water that we're allotted weekly, but it's fairly draconian. At this point, we're only allowed to water once per week, and we're permitted to hand water our trees throughout the week. But, having said that, we run a very small crew, and there's a mountain of work for us, and so we simply don't have the resources or time to go around watering thousands of trees that we have on campus. We're trying to focus our effort on our most valuable and our more vulnerable trees, hand watering, and also putting in lots of mulch to sort of retain some of that soil moisture around the trees. But it has been an uphill battle since the beginning of the summer. Actually, it's been an uphill battle these last few years, and it's only getting harder and harder. Some of our most valuable oldest species are on the verge of decline, if not already in irreversible decline.

ZIERLER: Who sets those limitations? Obviously, we want to save those trees. It's very important to give them the water that they need. Who is making those decisions about essentially life or death for some of our precious trees on campus?

VEJAR: That's a little above my pay grade. I've been handed down these restrictions from above, from our directors. Certainly, there is a lot of negotiation, a lot of compromise that went into it. We, of course, do need to conserve water as much as possible. All of us have to play our role in saving this precious resource that we have that's dwindling year after year. I understand that this is a critical venture in conserving water, and I'm working within the confines that I'm handed down. I don't have any direct say in who is actually making these decisions. I think a lot of these decisions are passed down from the city, from municipalities, from the Department of Water and Power, and from inside our own campus from our sustainability department to our facility operations. There's a lot of people who are contributing and making compromises in that way.

ZIERLER: Are you going off of the assumption that because of climate change, because of the things that we're dealing with in Southern California that these challenges are only going to become more critical over time?

VEJAR: One hundred per cent. Any time you work within a historic institution like this one, there's a lot of pride and there's a certain aesthetic, I should say, that we need to preserve. Being a historic institution, there's an ongoing transformative process, let's say. We certainly want to be in an appealing place for people to visit, for people to work, and a lot of that has to do with preserving a lot of our green. But, at the same time, we have to plan for the future. If this is literally the coolest summer that we'll ever have again in our lifetimes, then we need to plan for the future. That's planting species that are more climate adaptive. That's augmenting our old irrigation infrastructure, which is a whole nother mountain that we have to climb too because we certainly a lot of it. It's planning for the future. It's making repairs where you can. It's putting out fires [laugh], let's say, honestly.

ZIERLER: Well, Bryan, let's go back to childhood. Were you always interested in trees, and did you know that there was such a thing as an arborist, a career like this to pursue?

VEJAR: Well, like many kids, I certainly climbed my share of trees. I was always playing outside, and loving to be in nature. But, honestly, I didn't know very much about trees. I didn't know what an arborist was. I didn't know that there was a role for people like me in the industry, or that there was an industry at all, and so definitely not. Growing up, honestly, I think that a big issue for me personally was I wasn't a particularly good student. I was maybe a straight-C student going through high school. Went into college. Messed it up. Changed my major half a dozen times. I dropped out of college, and I was just working in the service industry. It wasn't until I decided to go back and try a couple new things in my junior college at the time that I took my first botany class. That was really where it all started for me. Botanical science is incredibly fascinating, and so that's where it all started for me.

ZIERLER: Where did you grow up?

VEJAR: I grew up in Southern California all around—La Puente, Baldwin Park, Glendora, Chino Hills—just kind of bouncing around but within the same 50-mile radius.

ZIERLER: Bryan, in the way that you, as you alluded to earlier, connect trees with broader social justice issues about wealthy areas and not-so-wealthy areas, and some of the obvious differences in terms of canopy cover, did your own background or the kind of places you saw growing up influence this perspective?

VEJAR: Absolutely. My grandparents were immigrants. They worked really difficult, long, laborious jobs. I grew up in a primarily Hispanic community. There wasn't a lot of infrastructure set in place to develop a nice urban canopy, and so the few trees we had in our neighborhood growing up were small. They were stressed. We had to go to the nicer area. We had to take our bikes and go to the nicer areas to really enjoy the outdoors. That's a shame because there's not really that much difference in the actual land and area as far as climate wise between certain neighborhoods and certain other neighborhoods that have a lot more resources.

ZIERLER: What does that mean exactly to have more resources at the infrastructure level? Rain goes where it goes. It doesn't care what the zip code is. What are the infrastructure differences that make wealthy areas greener than poorer areas?

VEJAR: Well, historically, there is a process called redlining, and that's where city planners would sort of segregate certain areas that were primarily made up of minority communities or low-income areas. These communities historically were underserved. There was a lot of circumstances that made investment in these communities difficult if not impossible. Whereas affluent areas and communities had the resources and urban planning to allot for a more green space. There was a lot more room for them in between structures, in between houses. The acreage per house was significantly larger. When you have a lot more space, you can afford and to both plan and maintain, for years, green spaces. These green spaces, when cared for and meticulously maintained, will develop into what we see today: large urban trees that have tremendous amounts of positive effects and add to property values as well; sort of a self-feeding cycle. In poorer communities, you would have a lot less space, or space is at a premium. Buildings and structures and hard space are more tightly clustered together. That doesn't leave a lot of room for trees to develop. When there is any money to allot towards infrastructure in these poorer neighborhoods, urban trees [laugh] are probably the last thing on the list that receive the attention that they so need.

ZIERLER: Bryan, from that botany class that you took, and you got the bug, you wanted to do something in this field, from that one class and discovering this interest, what did you do next?

VEJAR: Well, at the same time I was going back to college and taking botany, I just so happened to be a recreational rock climber. I was really into climbing. I remember one day, it was one day, and it changed everything. I had volunteered on a farm to do some veg management, some brush clearing. They had a team of volunteer tree climbers come out to work a number of trees that had been neglected for many years. When I saw those guys gearing up, getting their harnesses on, getting the ropes up, and getting into the trees, swinging around with chainsaws, and shouting, it was just an eye-opening moment for me. I knew then and there, I knew that very moment, this is what I want to be. This is what I want to do. I was into my mid-20s at that point. A lot of people are forced to decide their career paths early on in their lives or right out of high school. I was fortunate enough to be able to not lock myself into a certain career path too early. Now, I'm doing a job that I just absolutely love, and I'm well-tailored to. It was that moment that, really, the light went off. It was the rational union between the thing I was studying and the thing I was doing in my free time.

ZIERLER: Were there mentors, professors, older people in your life that gave you some advice about the best path to take, both in terms of education and certification, but also becoming an apprentice, getting experience out in the field?

VEJAR: Absolutely. I owe so much of my career path to just a handful of individuals, teachers, other arborists, other industry professionals that have helped guide me toward the career path I have today. I, myself, I try to take that energy and that time and that effort that they put into my life, guiding me, into our new hires here at Caltech. As a member of the FED Council—that's the Facility Engagement and Development Council—I'm trying to guide our new hires back into certification programs and collegiate programs that help them further their education in the horticultural industry. Hopefully, I'm kind of trying to pay it forward a little bit in the way it was paid to me when I was still asking my questions, and I was kind of clueless coming out of my botany and horticulture classes.

ZIERLER: What did you do next, both in terms of getting the experience and getting the education?

VEJAR: I went on to get a degree in horticultural science, and I got a job at Disneyland Resort in California Adventure as a tree climber. The reason I was able to do that was one of my old professors back at my junior college happened to be on the staff there—was an adjunct professor at the college, and happened to have a position at Disneyland, and she offered me the job. I happily took it, and I became a tree climber at Disneyland, something that [laugh] was absolutely surreal to do. If I had told myself as a child that I would be climbing trees in the middle of Disneyland, the same trees I walked underneath as a kid, I would just be like, wow, I've made all the right choices. [laugh]

ZIERLER: Bryan, from that experience, what did you learn about native and non-native species, because Disneyland wants to create an atmosphere where you could be anywhere, right? What did you learn in that regard?

VEJAR: Well, it takes a tremendous amount of effort. That's the biggest lesson I took from Disneyland is the magic of Disneyland is all the work that goes in from all the workers, everyone from landscapers, gardeners, arborists, to custodians and food workers. That's the real magic of Disneyland. To answer your question about natives versus non-natives in a place like Disneyland, there's certainly a push to sort of embrace the California aesthetic, to take pride in our native landscape. But that also has to be weighed against trees that grow lushly, that provide tons of shade. Those are generally tropical trees, and trees that don't do well naturally in our climate. They similarly require a great deal of planning, effort, and maintenance to preserve. It's difficult. I presume that the landscape of Disneyland will be completely changed in the next 50 years because even some of our most lush species that we like to plant in areas like Disneyland just won't be able to withstand the climate as it changes.

ZIERLER: What was Disney's approach both to irrigation and hand watering? What was manual, and what was automated because the infrastructure was there?

VEJAR: Well, I should say, Disneyland has a tremendous amount of resources at their disposal. When I worked there, which was about, gosh, 12–13 years ago now, water restrictions weren't so draconian. Though we were in effect a drought, the restrictions weren't really as in place. The industry is still evolving. We're trying to retrofit a lot of our overhead sprinklers to drip irrigation. There's a lot of reclaimed water going on in both Disneyland and in our communities as well. We're having to cope piecemeal with the realities of a changing climate. Within Disneyland, I would expect that they're continuously innovating. They're continuously flush with resources to preserve their landscape and their trees. Unlike a lot of places, I think that Disneyland can make do. [laugh]

ZIERLER: What did you learn about safety considerations? Obviously, Disneyland is teeming with people. How do you care for the trees in a way that you can maximally avoid any unfortunate mishaps like limbs falling and things like that?

VEJAR: Well, that's a concern everywhere: Disneyland; Caltech; when I was working commercially as well. That's another one of those tightropes I was talking about. On one hand, you do want a robust, capacious canopy that gives a lot of shade and a lot of value to an area. But you also have to be somewhat conservative with how large you can allow a tree to get. You have to have a keen eye for branching ends defects, cavities, infestations of different kinds of pests that might contribute to any mechanical weakness of trees. There's also a factor of the unknown. Sometimes, limbs that are perfectly well-attached and robust and large, and don't have a lot of wind shear, even those can fail. That's nature. That's biology. To answer your question, it's impossible to predict a failure in a tree that otherwise doesn't show any signs or symptoms. But that doesn't mean that the failure is at zero. There's always an associated risk with trees because they are living dynamic structures.

ZIERLER: I wonder in that vein if you can walk me through looking at a tree, both at a distance, and then both up close. What are the things that you've been trained to see to understand here's an area of concern, this is something we're not concerned about, both from looking at a tree from a distance of, let's say, 50 feet, and then right up to right in front of your nose where you're really getting in there and seeing what's going on? What's that process like?

VEJAR: I'll start by saying it takes a tremendous amount of field experience, and also it takes an ongoing acknowledgement and refresher in the best management practices of our industry. We have to continuously allocate our attention, our time, our resources to learning more about how trees function, and how they fail. If I'm walking up to said tree, and I'm 50 feet away, I'm immediately noticing, like, first of all, I'm identifying the tree. Nothing can be done until you identify the species of a tree, and have some comprehensive understanding of its biology, its tendencies. Certain trees will look certain ways in certain times of the year. Certain trees won't look certain ways in certain times of the year, a tree's deciduous or it has dead wood, that you would not necessarily know until you get closer up. You're looking at the quality of the canopy, its leaf coverage, its canopy distribution. You're looking at overall limb structure, how large it is, if there's any apparent lean. You're also taking into consideration all kinds of other site conditions. Is it on a slope? Is it in a confined tree well? Is it next to a building? Is it being shaded out? Is there reflected light off of some building window that might create hotspots on the tree? Is there any dieback in the tree? Are there any apparent broken limbs from when you're first looking up? What is the traffic like around that tree? Is it in a nice open area or is it surrounded by hardscape where people and vehicles are emitting exhaust all the time? These are the conditions you're looking at immediately from afar.

As you're getting closer to the tree, your eye is trained more towards individual things like what is the bark looking like? Is it flaking off? Is it exfoliating in a way that would point to some stress, some amount of stress for a certain species? Are there cracks in the bark? Are they vertical or longitudinal? Are they longitudinal or are they parallel with the ground? Are the leaves chlorotic, that is to say, are they yellowing or do they have spots on them? Are there any apparent pests that you can see on the tree as you're walking into it? If so, are they regular native pests that are normally on these trees or are they something else that might trigger a deeper more advanced risk assessment of this tree? Are there any fruiting bodies, any funguses at the base of the tree or along the trunk? Are there any cankers, any sap coming out from old wounds or from non-apparent wounds and sunken areas along the tree—along the trunk, rather? [laugh] I think I covered a lot of them, and I'm sure there is even more.

ZIERLER: Now, at this point in your career, have you built up a visual database in your head? Do you basically have the ability to identify most any tree species just on sight?

VEJAR: Oh, yeah [laugh], in fact, this has become a sort of running joke with my friends, and my fiancée as well.

ZIERLER: Stump Bryan, right?

VEJAR: [laugh] I cannot keep my eyes out of the tree.

ZIERLER: [laugh]

VEJAR: I can't pass a tree without doing a cursory visual inspection of the tree. Sometimes [laugh] even while driving, I have to remind myself to keep my eyes on the road, and not—

ZIERLER: [laugh]

VEJAR: —pay attention to that leaning tree on the freeway embankment. This goes probably for any discipline. The more you experience and look at it, the more you all of a sudden build up this internal database where you can immediately key into some defect, something that's just off about it. It takes a little more investigation to really come to an educated conclusion about the condition of this tree.

ZIERLER: Bryan, let's move now to the arborist's toolbox. Once you've identified all of these potential areas of concern, what are both the tools and the medicines that you're working with to keep trees healthy?

VEJAR: Well, a lot of our tools in preserving trees go towards preventative maintenance of these trees. The number one thing that you can do to preserve the health of the tree is to improve site conditions for these trees. A lot of times, you won't really know if a tree is stressed until it's well into its infestation or well into its malady, so to speak. A lot of the tools that I use are like, for instance, I'm a tree climber. I get up in the tree. I get a very close, intimate look at the inside and outside of a tree on a daily basis. This usually happens while I'm pruning trees. A lot of people say, "Oh, you're going up there. You're cutting branches. You're clearing it out." But being an arborist, you really understand that you need a light touch up there. Trees have an economy of resources inside them, in their branches, in their leaves. If you take too much off at any given moment, or annually, you really limit a tree's ability to keep itself healthy. Worldwide, arborists are sometimes called tree surgeons. I really like this title—a tree surgeon—because you're essentially doing surgery in there. Surgery on people could be a lifesaving, really beneficial thing. But if you do it too much, and only for cosmetic reasons, then you can perhaps have some health complications. It's the same with trees as well. Since I've been here on campus, we've kind of shifted towards a less clean and open aesthetic, and more of a natural aesthetic as well. That's my physical tools, basically, my cutting instruments, my own efforts physically as well. As far as medicants, the industry always evolving. We have fungicides and insecticides and other chemical compounds, both organic and synthetic, that we use on our trees to stave off the worst symptoms of some of these infestations or some of these maladies. Having said that, chemical use is usually the last line of defense in a tree. You want to first improve the site conditions to aid a tree in responding naturally on its own over time rather than continuously use expensive chemicals to preserve a tree, which might only be a temporary fix.

ZIERLER: Bryan, to go back to the chronology at Disney, what was the reporting structure? What was the group that you were in? Was there an arbor division of Disneyland? How did that work?

VEJAR: In fact, there was about a dozen or so tree climbers. A few of them were certified arborists as well. They also had a tree risk assessment department specifically walking around on the ground, flagging trees for further investigation. Then, some of the tree climbers would get in, and report back. Is this tree looking like it's ailing? Is this tree looking like it is stressed out? They will build a comprehensive profile of each specimen, take inventory of that specimen, and make recommendations based on those findings, those observations. There was never anything less than a few different individuals looking at every specimen to confirm the health of each tree that we were looking at.

ZIERLER: Is there a chief arborist who ultimately makes decisions based on those recommendations?

VEJAR: Yeah, absolutely, there was the lead of our arborist crew, another certified arborist, and a very accomplished climber as well. He dictated what our goals were for the day and for the week, set out our work hours, and reserved work orders as well as handed down from the tree risk assessment department as well. There was always meetings about what to do in certain scenarios, what our objectives were with certain preservations. Sometimes there was construction that we needed to do risk mitigation or damage mitigation for certain trees. I remember when I was working in the Jungle Cruise, for instance, there were helicopters flying in new animatronic animals, and we had to pull trees apart from one another and cable them apart in order to get in with the helicopters and drop off these things. It was a whole process, and so it's a lot of moving parts at any given moment.

ZIERLER: Was there a favorite area of the park for you, a place where there were the most interesting trees so the most interesting problems to work on?

VEJAR: That's a tough one. The Jungle Cruise was awesome to work on, but it was tough too. It was really wet and muddy in there. [laugh] I'm not sure if I've mentioned this but everything was done overnight, and so it was all in the dark. We only had our tower lights and our headlamps to guide us through these trees. We're climbing in the dark. We're working in the dark in times where most people are asleep. That added a certain dimension of difficulty and challenge to the job, but also it was nice to not [laugh] work around pedestrian foot traffic and other people. As opposed to here at Caltech [laugh], all our work is done while classes are in session, while meetings happen, while research is getting done. It's a challenge to sort of navigate these schedules in order to essentially operate a tree service within the campus as it's running.

ZIERLER: Bryan, what did you learn first at Disney and then coming to Caltech about making that ultimate decision, when a tree needed to come down?

VEJAR: This decision's a really tough one to make. Obviously, our preference is to retain and monitor any species—any specimen, I should say. Trees are tremendously valuable, and they take a tremendous amount of time, generations of time in order to mature and provide all the value that we know trees give us. Ultimately, it comes down almost always to a matter of safety. Safety is our number one concern—it was at Disneyland, and it is at Caltech—with all the tree work. We have to preserve the safety of both our crews, our workers, and also either our park-goers or our Caltech community as well. It's the same everywhere. When you look at a tree, or when we're investigating a tree and doing a risk assessment, we will basically pull out all the stops in order to preserve it. But, ultimately, trees are living things too, and they have their own natural lifespan, and they will go into decline, and they'll die off. When they die off, certain species are more likely to fail than others. Certain species like oaks, they'll probably stay up for hundreds of years, even after they're dead. Certain other species like liquid ambers or some of our imported species from other places in the world will develop a cavity at the base, and will then become unstable, and will fall over. This is something that we simply don't allow. In fact, in the years I've been working at both Disneyland and at Caltech, I've only observed a few small catastrophic failures. Given the fact that we worked on—and I personally worked on—thousands and thousands and thousands of trees, that's saying something.

ZIERLER: Now, did you get your certification during your time at Disney, or you came in with the certification?

VEJAR: I came in with the certification. Actually, no, I'm sorry, I didn't have my certification when I was working at Disneyland. I started off as a grounds worker there, and then I had to prove my ability and my know-how in the department as a climber, as a risk assessor, as a safe worker. They didn't let me up in the ropes for quite a while. Once I did demonstrate my proficiency with climbing, then I was able to contribute to the crew in a more meaningful way. I left Disney, and started my own tree care company for about five years out in my community in Claremont. It was during that time that I studied for and applied for and passed the ISA certified arborist exam.

ZIERLER: What were some of your inspirations for striking off on your own, becoming an entrepreneur?

VEJAR: Well [laugh], for one, I didn't want to work overnight anymore. [laugh]

ZIERLER: [laugh]

VEJAR: That was a tough go. Anybody who's worked the graveyard shift will tell you. It messes with your life in a lot of ways that you won't anticipate. Even working a dream job, like the one I had at Disney, had a lot of challenges and a lot of obstacles, and I simply couldn't. I'm a morning guy. I like to be up early in the morning, and I like to be out in the sun, and be out in the day. I simply couldn't do that at Disney. I left Disney, and I went back with my old native landscaping crew, who didn't have a tree care company at the time, and I pitched this idea that I would come back as the arborist for the company and, eventually, start my own service under their banner. To their credit, they were super supportive of that idea. They knew my passion. They knew my proficiency. Instead of outsourcing their tree work to other tree companies, they wanted to do it in house. They gave me free rein to run the tree service under that name. I did so for about five and a half years. That was great. But, also, the commercial tree care industry is absolutely fraught with non-professionals. Anyone can get a rope and a chainsaw, and call themselves a tree worker, with little to no legal ramifications. Certainly, you have to be a certified arborist in order to call yourself a certified arborist. But many people don't look for certified arborists when they're having people work on their trees. They just want somebody to come out and do it quickly, do it safely, and do it cheaply. I can't tell you how many times I was outbid on jobs that I was well-researched and well-prepared and ready to do by someone who is doing it for basically nothing. They'd come in, and they'd do a hack job on the tree. They would injure the tree, and leave, and they wouldn't come back. I struggle to think of very many other industries—trade industries—where a huge, significant proportion of the workforce are untrained professionals. But that's the reality in the tree care industry right now.

ZIERLER: I wonder how much of this is tied up with larger immigration issues, and the lack of regulation.

VEJAR: One hundred per cent, it's tied into that. I think, traditionally, tree care has been sort of framed as a low-skill or no-skill job. It's a tough job; very difficult physically to get up there, and a very potentially hazardous and injurious job as well. But because it's a dangerous job, it's not as appealing perhaps to educated professionals, and so you have to sort of have the right balance of fitness and physical capability to be a climbing arborist while being well-versed, well-educated in order to really apply that knowledge, that technical knowledge toward tree preservation. That's especially critical in Southern California, where trees take a lot of care and maintenance to help them thrive.

ZIERLER: Bryan, tell me about some of the communities you served in Claremont.

VEJAR: Well, I lived in Claremont for about 14 years. My job took me as far east as Riverside all the way down to Santa Monica. I took jobs wherever I could, honestly, because I had to. When I'm running the service, I even had to take a second job in the evening as a server, just to pay for my first job, to keep my guys employed and to keep them paid, and keep myself afloat as well. It's super cutthroat, so I took jobs that would barely pay off, and under tight schedules too. But I never wanted to compromise the quality because I felt like that was what I offered my clients. I could speak to them articulately about what I was going to do, and what I planned to do. I made myself available to them afterwards as well so, that way, I would build a relationship. In a way, I was sort of selling myself; not the actual tree work. Then, I would follow up, of course, with the good tree work, and they gained trust in me. I had built up a fairly sizable client base by the end of those five years.

ZIERLER: Let's go through some of the ins and outs of tree climbing. First, in terms of worker safety, what are the basics? What do you need to do in order to be safe?

VEJAR: Well, first of all, safety is absolutely paramount. We have to use all our PPE, our helmets, our safety glasses. We have to do visual and routine inspections of all of our climbing gear in order to make sure that it still meets American National Safety Institute Standards—ANSI Standards. We also have to retire a lot of our equipment after a certain number of years. I have gone through many ropes that were in pristine condition after meticulously taking care of them for years, just because you can't continue climbing on the same ropes for too long or else, like, that - the best management practices. You have to replace and renew and maintain all of your equipment in order to climb safety—and that's as a climber. But also as a climber, you have an obligation to those underneath you as well to communicate effectively with your grounds members to make sure that they're wearing their own personal protective equipment, and to make sure that you're working in a safe manner, and not to compromise the safety of anyone else. If I make a mistake up there, if I am shortsighted and I do something wrong up there, maybe I'm stuck up there, and if my ground crew put themselves in danger to come and rescue me, then I'm essentially putting other people in danger as well—or first responders as well. I'm really looking after myself up there, and I have to maintain a high level of safety-mindedness in order to make sure that I'm coming down safely, day in and day out.

ZIERLER: Bryan, what about the tree itself? What are some of the dos and don'ts about not harming the tree when you have to climb it?

VEJAR: Well, we were talking about untrained professionals climbing trees earlier, and something that is killing me when I see it is tree services and tree climbers using spikes in trees that they don't intend to fill. Spikes, of course, should be relegated only towards working trees and spars, that is, trunks that are delimbed, or removing trees or in rescue operations when the health of the tree takes a back seat to rescuing something or a utility—somebody who's hit a utility line, and needs to be rescued out of there. Then, of course, you have to take every tool you have out of the bag, and make sure to solve the situation. But it kills me when I see climbers climbing trees with spikes, making bad cuts, making flush cuts, that is, making cuts on branches that are up against the trunk. Trees have internal physical chemical barriers in the canopy that if you cut a certain area, they won't be able to withstand any infestation or any new pathogen, or halt the spread of decay. You have to have a working knowledge of how best to prune and work a tree to prevent the introduction of pathogens and also decay in a tree. Also, routine sterilization of your tools, maintaining your tools well, not taking too much out of a tree at once because then you can lead to a chronic stress of the tree as well.

ZIERLER: What were some of your proudest moments in terms of making homeowners happy? They were very scared that they would lose their tree, and you came in and saved the day.

VEJAR: Well, I'll say, I wish though I had a lot more instances in which I saved trees. But the reality in a commercial industry is that people usually won't call you to come in and evaluate their tree until it's been dead for maybe some time, or it's well into its mortality spiral. This is the reality of trees is that they will be communicating their stresses and symptoms to you for many years, and you might be blind to it until your tree is almost dead. Having said that, I have had a number of really great successes with clients where I introduced a healthcare program, a long-term healthcare program for trees, or I've done some restorative pruning when they had a non-professional or poor tree service come out and hack the tree or top the tree. For all that harm that was done so quickly to that tree, it takes many, many years of planning and pruning to restore the natural shape and natural vitality of the tree. It's a difficult thing to do to help a tree, but it's probably one of the most rewarding parts of my job is to see something that is struggling, and help it to thrive.

ZIERLER: Bryan, given the large geographic area, the very diverse communities that you served during this period, is that where in your career you started thinking about ways where you could use your area of expertise for social justice, for balancing out poorer communities so that they could have better tree cover?

VEJAR: Absolutely. I gave the same quality of care to my more affluent clients than I did to ones whose resources were a lot more limited because, in my view, while I might have some financial stake in helping more affluent clients with their trees, I had a vital social role where I could help preserve the value of somebody's property, or help assuage any fears that the tree might fall and harm them, do some preventative maintenance to put their mind at ease, and treat them and their trees like they're pristine specimens, like they're historic specimens or something. I'm not just working for the people too. I see my role as speaking for the trees, for helping the trees, being the lawyer for trees, negotiating on their behalf on their health, and then helping them thrive. In that way, I feel that I am trying to improve my environment, improve my social surroundings, and there's a little bit of kind of karma to it. You're helping people. You're helping your colleagues. You're helping your coworkers and your community, and you improve the things around you, and it comes back to you in a way that may be ephemeral. It might be nebulous in your brain. But it makes me happy. It makes me happy to apply my efforts towards improving my world.

ZIERLER: Bryan, is there a continuing education component? Do you need to take refresher courses for your certification?

VEJAR: One hundred per cent. In the ISA, it's mandated that you recertify every three years. You have a certain number of what are called Continuing Education Units, CEUs, that you must satisfy in that three-year timespan. Every time you attend a seminar, every time you attend a workshop, or you submit an exam test, any time you participate in a voluntary event where you're contributing your skills and know-how, these qualify for Continuing Education Units. You have to be a continuously engaged professional, and you need to stay aloft of the latest research and industry knowledge in order to maintain that certification. I absolutely love that. I love that about certification because if you were simply to study your butt off, and maybe you study all the textbooks, and you luck out on that exam, and you just barely pass, and you never think about it again, are you really truly qualified to represent us at the higher tier in our industry? I would say no. If it wasn't for this Continuing Education Unit requirement, I would say the title of certified arborist wouldn't carry as much professional weight as it does now. There are other certifications. For instance, I told you earlier that I'm a Tree Risk Assessor as well. That also requires recertification and Continuing Education Units. Finally, the final top tier of our industry is the board-certified master arborist certification. This is something I'm currently working toward right now. That will require an increased amount of Continuing Education Units year after year in order to satisfy those requirements.

ZIERLER: What will you be able to do at that level that's not possible now?

VEJAR: Good question. I've always seen it as a personal endeavor. I have always wanted to be the best arborist I can. I want to be able to speak with some authority in my field to convey these ideas to the public, to represent my trade in a way that is articulate but also accessible as well. I see my path toward becoming a board-certified master arborist in that light. That'll help me gain some authoritative weight behind my word. But, honestly, it's a lifelong learning experience, being an arborist, in my opinion at least. In another 50 years, I will still be thinking about trees, and learning more new things about trees that I had no idea about, or refreshing old knowledge that maybe I might have left back in junior college. I love refresher courses. I love diving back into like first-year kind of tree and plant biology too because it reaffirms and it kinds of strengthens that grasp on your expertise, those neural networks. [laugh]

ZIERLER: Bryan, what about conferences and conventions? Are there opportunities to learn from peers in the field and to interact with commercial companies, suppliers, and get a sense of the latest products that are out there?

VEJAR: Absolutely. Other than the educational aspect of these symposiums and conferences, I think right up there is being able to communicate and build relationships within your professional community. It's critically important that we do that because perhaps I'm running into an issue that I have very little experience in, or I need a second opinion on something. It helps me to be able to draw on not only my own body of experience but also those of my peers and colleagues as well. I have many, many colleagues that work in the arboretum, at the Huntington Library, in municipalities around Pasadena and San Marino, in Claremont and Upland. I've built these relationships, and they're so important to me, and I try to make myself available to those people as well as they need some help with something, some know-how, or maybe just they need another planting supervisor for a tree-planting event or something. I feel like the more time I spend in my industry, the more people I get to know, the more it becomes a little bit of a small world, honestly. I recognize people from back in college. I recognize people from old jobs, old colleagues, old coworkers, old employees in other positions. It's wonderful to see people developing in their own career paths, and it is extremely useful to build those relationships in this industry to improve my own body of knowledge.

ZIERLER: Bryan, when the opportunity at Caltech came available, were you looking for a change of scenery at that point, or this just came out of the blue, and it looked too good to pass up?

VEJAR: A little bit of both, honestly. I loved so much about the tree service: the flexibility, the fact that I was building my own name, and I was putting myself out there. I could choose to work for a week. I could choose to not work for a week at certain times. I was putting my all into it. It was my face, my name, everything. But, having said that, like I said earlier, it's a cutthroat industry. Some months were great. I was making a lot of money. I felt like I was getting the value that I had put into my company and my tree service. Then some months were completely destitute. I had little work. I was scrounging by. I was losing sleep on jobs that had to be done in a certain time by a certain date, or else I wouldn't make any money. That was a tremendous stressor on my life. While I'm thankful for that experience, I had started opening myself up to the possibility that there was another role for me out there. Something about me is when I'm in a position in a career or in a job, I'm all in. I need to be all in because I feel like my success and my value is a function of my effort that I put in. I think it was probably in a stretch of tough times that I'd gone online, and said like, yeah, what kind of jobs are around here? What can I fetch out there? What kind of opportunities can I find?

I stumbled upon the job application for the tree care specialist here at Caltech. It wasn't known as campus arborist at the time. It was just called tree care specialist. I had always had a reverence for Caltech, what Caltech represented in our community, what it stood for. As an arborist, as a horticultural scientist, I wanted to approach my position like a scientist, using the scientific method, and adhering to the honest assessments and self-assessments and peer review that science kind of champion. I saw Caltech as this incredible institution in this beautiful area, and I thought, oh, my gosh, I have to. I have to give it a shot. Even if it's a long shot, I have to try. I applied. I applied to Caltech, and I heard nothing back. I even followed up a week later, and then two weeks later—"just following up on my application, my cover letter, seeing what else I can offer, if you need any more, if you have any other questions"—and I got nothing. [laugh] I said, OK, back to work. Back to planning my weekly schedule. Back to everything. It wasn't for a couple of months that I finally got called in for an interview at Caltech, and I was elated. I was like, OK, I have a chance. I have an opportunity. I had tree brain. I couldn't sleep that night—

ZIERLER: [laugh]

VEJAR: —because I was so excited about interviewing. I had my first interview, and it went so great. I was so happy to be talking about trees. This is the one thing I do probably too much [laugh] is talk about trees. I was thrilled to be interviewed by Delmy Emerson and Ryan Robitaille, both of whom have a tremendous amount of working knowledge of trees, being arborists as well. I felt like the interview went so great. I felt like I had built a good rapport, and I'd represented myself well. I left thrilled. I didn't hear back for months.

ZIERLER: Did you get a tour of the campus? Did you get a chance to look around at the trees on campus?

VEJAR: I did, and not from the interview. I had done my homework on the institution. I took my bike around every publicly accessible space around campus, building up sort of a mental map of the campus, and maybe kind of coming up with my own like assessments of the tree work that had been done up to that point, things that I loved about it, things that I had some critical assessment on, and trying to really kind of elevate my status coming into the interview. But after that first interview, not having heard back for a couple of months, I had slowly slipped into the like, well, the interview was a good experience. I'm glad I had this experience. I still love Caltech. Then several months later, I got my second interview, and that's where things started rolling. [laugh]

ZIERLER: Bryan, from that first informal bike tour around campus, what were your takeaways? What was campus doing well, and in what areas did the trees really need work?

VEJAR: Well, one needs to only walk through the campus to see that we have a very robust, well-maintained, well-preserved canopy. We have old specimen trees, rare specimen trees on campus as well, a well-developed canopy. Cosmetically, absolutely immaculate in a lot of ways. There was a lot to admire about the landscape coming in. They had done a tremendous job up until I came in. I think my criticisms of the landscaping coming in were in line with sort of how the industry more broadly was shifting from less of a cosmetic and a clean appearance to more of a natural shaping, and allowing trees to kind of fill out, and allowing trees to gain in capaciousness and in canopy size. Also, as I mentioned before, we have a lot of trees planted in turf. But now the industry is shifting away from turf and more towards mulch and ground covers and perennial herbaceous plants as well. I think that my criticisms were limited but there were important distinctions from where the campus had been before, and where it had to go when taking in climate change and our water restriction into account.

ZIERLER: As part of that second interview, were the people you were talking with, were they receptive to your ideas? Did they welcome the idea that you were proactive, that you saw things in areas for improvement?

VEJAR: I can't jump into their brains, but I feel like that was one thing that kind of set me apart as a candidate in that position was that I had developed my own opinions about campus about where I wanted it to go or what direction we want to head to. Something that always from that day until day stuck with me, I remember my ground supervisor Ryan Robitaille, he told me that he wanted someone who would take ownership of the trees. Ever since then, from applying for the job to working the job, and being here right now in this instant, I feel that these are my trees. I take care of them because they're mine. They're my own. When we lose one, it hurts. When we plant new ones, I'm excited, and I'm excited for what they will become. I come on my days when I'm not working. I come to campus just to look at the trees, to enjoy the shade of those trees that, just days before, had kept me aloft from falling on the ground. [laugh]

ZIERLER: [laugh] Bryan, as you mentioned, you were a long-time admirer of Caltech and what it represented? Being an institution that takes the science and engineering so seriously, in what ways is that a built-in advantage for success in what you do?

VEJAR: I'm sorry, can you repeat that question?

ZIERLER: Science and engineering are taken very seriously at Caltech. Your work is dependent on science. Is there something about just the culture of Caltech that makes your job more fulfilling or easier or more impactful because of your reliance on the science to do the job correctly?

VEJAR: One hundred per cent. I feel like all of us in facilities could sort of take up that banner of the spirit of inquiry, of peer reviewing, of all the scientific methodology. If we approach our jobs scientifically, we position ourselves to be able to not only effectively address issues and obstacles and challenges but also to learn from our mistakes, to move forward, to learn new innovative ways, and to implement those innovations into practice. That's a big part of science, and that's a big part of what we do here, even in the grounds shop. I remember our incoming director, David Kang, was telling us about this anecdote from NASA where John F. Kennedy had come into NASA, and he asked the custodian, "What are you doing here?" He says, "I'm helping put a man on the moon." I feel like that way, all of us in facilities, from custodians to plumbers, electricians, groundskeepers, painters, we're all helping to propel the institution of Caltech forward. Now, as for the community, it's been so welcoming. Some of my closest friends are students and postdocs here. Others are faculty, staff. It's been such a welcoming, warm community, and I'm so fortunate to work here. Because I took ownership of those trees, because I know the importance of a robust canopy on our mental health, I think that in some small way, I'm helping to add prestige, my little bit of prestige, a small amount prestige to this institution.

ZIERLER: Bryan, if we walk around campus today, where might we appreciate your fingerprints, all of your skills, all of your experience that we can see, that we can say this tree is here as a result of your efforts?

VEJAR: Everywhere. I know [laugh] what you'll say. You want specific areas but, honestly, I find I work every single tree on and around campus. Like any industry endeavor, there are failures and there are successes. A lot of people know about the founder's tree in 2016. That was before my time. But you have a tree that was probably of the utmost importance on campus, and we had a variety of experts from in house and from outside come and evaluate this tree, worked to preserve this tree, because it was our founder's tree. It was a tree that existed as a symbol of the institution. That tree died but that's nature. Trees are not eternal ornaments. They're living, and they get stressed, and they die as well. I have many trees on campus that I'm super proud of that we've been able to preserve and bring back from stressful times. But, I got to tell you, it's getting harder and harder. We have so many species on campus that were planted in a time before we really took climate change and water restrictions seriously. Maybe they weren't even thought of at the time. A classic example: we have about 130 redwoods on campus. Coast redwoods are California icons. They're our state tree. They're magnificent specimens. They're very distinctive and unique and dynamic, and we love them. Out of those 100-so trees that are on campus, maybe only a handful are truly healthy right now. They're getting scorched year after year. Even if we were to water them intensively more than we're allotted, we still wouldn't be able to preserve them because they don't belong down here. Part of my job—

ZIERLER: It's about the heat is what you're saying?

VEJAR: It's the heat. It's the heat. It's the lack of water. It's the certain pests that we have that are more common down here than they are up there. It's a combination. It's a confluence of forces that usually leads to a tree's decline. We have a lot of different specimens and species on campus that are not climate adaptive that we'll have to move away from in the future. As much as it pains me, we're going to have to fell a lot more trees in the future. That's just part of it. We have to replace them with trees that will thrive and/or at least will be more adaptive in the future. Where you see my fingerprint is everywhere. The whole campus canopy is a big urban fingerprint. [laugh] But heavily forested areas like or, I mean, I'm sorry, what I mean to say is particularly dense areas around Throop Pond, around Caltech Hall, behind many of our faculty housing areas, these are trees that have taken a lot of work to preserve, to maintain, and to beautify over the years, and I'm really proud of it.

ZIERLER: Bryan, what do you have to say about all of the olives that we see falling on the ground in the fall? Would you like to see them harvested? Is there a better use that we could have, other than them dotting the sidewalks and the lawns?

VEJAR: This is a tremendous part of our maintenance, year after year, and we're trying all kinds of different remedies to eliminate what is essentially a nuisance fruit. Before, I think it was in 2015, we had a program to harvest the olives, to press them, and create our own olive oil as well. I wasn't around during that time, but I have learned a great deal about it. The truth is that it was a very resource-intensive process full of a lot of really enthusiastic volunteers, but that volunteership declined over time, and the resources were reallocated. Any olives that are planted these days are a particular variety of fruitless olives. Olives are a great tree. They grow, they're very resilient to drought, they take a hard prune when they need, and they bounce back very well. They have their pests and their diseases as well but not a ton. They're really great California trees. They're Mediterranean climate but they're a dry climate so, once again, they're drought-resistant, and we love them.

But our old olives, we've been treating them with different what are called plant growth regulators, PGRs. This process, there's a very tight window to treat these trees. We have hundreds of olives—not just on Olive Walk but all around campus and faculty housing as well—all of them producing that nuisance fruit which stains the sidewalk. It comes down to all hands on deck. We're putting all our guys out there, and trying to treat these trees. Even in the best-case scenario, our most expensive products that we use are about 75% effective. It's an expensive process, and we don't have limitless resources here on campus too. We try to treat the ones that are the most highly traffic area. We try to time our pruning cycles to eliminate some of the flowering as well, to prevent some of the fruiting. For as much of those olives as you see on the ground, if we didn't put any effort into them, we'd be knee-deep in olives otherwise.

ZIERLER: Now, does this chemical treatment render the olives unsafe to eat? Are there warnings that people should be concerned about?

VEJAR: Not at all. What the synthetic PGR—the plant growth regulator—does is it mimics the natural chemicals inside a tree that triggers fruit senescence, that is, fruit drop. If you can get those fertilized ovaries of the flowers, the tiny little olive flowers to drop before the fruit actually set, then you will have effectively eliminated the fruit. The remaining fruit on there don't have any pesticide or, in this case, herbicidal residue or anything like that that would render them unsafe. Once again, safety is our absolute paramount concern on campus. We don't take any chances with anything that could potentially cause harm to anybody passing by or even our squirrels and wildlife. We don't want them dying, eating toxic fruit or anything. That would not fly on campus, and we have way too many red-tape safeguards in order to prevent us from doing that—and rightfully so.

ZIERLER: Bryan, for the last part of our talk, I'd like to ask two questions that look to the future. Going back to this example of the redwoods, and you thinking generations out where, ultimately, all of them will be replaced, what are the kinds of trees that are your go-to that will do much better in this new climate reality that we all face?

VEJAR: That's a really great question, and we are finding out still. Of course, I would love to incorporate more native trees. We do have a host of native trees that do well in our climate, but these trees are not particularly good shade trees, honestly, and shade is something we really need to bring into campus in order to keep our pedestrian walkways habitable and nice. We want to keep the cool and inviting environment for not just our students and faculty but for visitors to campus as well. We need to use a combination of native trees that we haven't planted before, like California buckeyes and desert willows, increasing the amount of mesquite trees, that are going to be doing well in our climate with little resources. But, also, we want to take more seriously our introduction and import of non-native species, especially from places like South Africa, Australia, Southeast Asia, areas that have really intense weather extremes or otherwise have very dry summers. I think when people think about importing non-native plants and trees, rightfully so, some alarm bells will go off in their head. Some red flags will be raised. We have learned so much in just even the last couple of decades, let alone the last 50–100 years about what trees are invasive; which trees will thrive; how to cultivate varieties that are not threatening to local ecosystems. I think that we talked earlier about this contentious issue within our own industry, and more broadly in the community. We certainly don't want to cause catastrophic invasive species to come in and disrupt our local ecosystems. A big example with the blue gum, the eucalyptus, which was imported heavily in the 18 and early 1900s into California. For a timber tree, it grew really quickly but, also, it made terrible timber products. The wood wasn't really good for burning, for cooking purposes or eating purposes. They were prone to limb failures, and introduced all kinds of non-native pests into our environment. That was a bit of a catastrophe. But we've learned so much more, and now we can import species that we know would do great in our communities, even certain species of eucalyptus. There's 750 different varieties of eucalyptus, and they're not all bad. They're not all destructive to our habitat.

ZIERLER: Finally, Bryan, last question. Is there an area on campus that you view as a blank canvas or an area where you have dreams of creating something really special? Do you define your work ambitions in a way that there's something that the campus community might get excited about in the future for what you might be able to create?

VEJAR: Every empty plot of land, every bit of turf that's been let dry out, every piece of parking lot that is a little too extensive, every walkway or parkway that could be expanded a little bit more, I have my eye on it.

ZIERLER: [laugh]

VEJAR: I'm making mental notes. I'm taking pictures. If I had my way, I'd turn the campus into the black forests. [laugh]

ZIERLER: [laugh]

VEJAR: It would be so heavily forested, you could barely see the sunlight.

ZIERLER: [laugh]

VEJAR: [laugh] No, not really but, honestly, I want to put trees wherever I can, anywhere I can: big trees, small trees, expansive trees, trees that are deciduous, trees that are drought-resistant. I want to increase diversity. I want to put, honestly, everywhere. But that's tough because Caltech, there's limited space in Caltech, and a lot of that is earmarked for construction purposes, for utility purposes. It's not as simple as putting a tree in the ground. You need to build infrastructure around that tree in order to help ensure that it thrives, or else all that energy, time, and resources that went into putting those trees in will be for naught if the tree fails or if it declines rapidly.

ZIERLER: Bryan, this has been a fantastic conversation. I'm so glad we were able to do this and, in our own small way, transmit that appreciation for what a beautiful campus we have, and all the benefits that confers. I'd like to thank you so much.

VEJAR: Thank you. This was such a pleasure to do.