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Hanna Makowski

[00:00:00] Michael Hawk: Have you ever wondered how biologists figure out how plants respond to drought, heat, cold, and other environmental factors? Well, one of the ways they do it is to study phenology. That’s a fancy word that accounts for seasonal and cyclical growth patterns of plants and animals. Researchers can look at various attributes, like when a plant flowers, when it leafs out, drops its leaves, and much more.

[00:00:21] And then they can see how that correlates to other factors like the environment, weather, climate, and even genetics.

[00:00:28] Today, our guest is Dr. Hanna Makowski, and she tells us all about her research at Black Rock Forest in New York, and surprisingly, why she’s had to become proficient with a shotgun to help with her research.

[00:00:40] Dr. Makowski shares her work on understanding the variations in leaf out and leaf drop phases among trees, the genetic and environmental factors driving these changes and the broader implications for biodiversity and climate change adaptation. Blackrock forest is a special place for this kind of research because it’s in a transition zone where some Southern species and Northern species meet.

[00:01:02] I know that if I ever find myself in New York, I’m going to want to visit. Dr. Makowski’s findings could be helpful for tree conservation efforts and predicting forest resilience in the face of global climate shifts. You can find Dr. Makowski on her website at http://www.hannamakowski.com, on Twitter at @hannamakowski and on LinkedIn.

[00:01:22] And of course the spelling and links are in the show notes. So without further delay, Dr. Hanna Makowski.

[00:01:30] Dr. Makowski, thank you so much for joining me today.

[00:01:33] Hanna Makowski: Yeah, thank you for having me. I’m excited to be here.

[00:01:36] Michael Hawk: , we were just chatting a little bit before I hit record. And this is one of those topics where I know just enough to be dangerous, but I also don’t know what I don’t know. So, I’ll probably ask some silly questions as we go. and hopefully you’ll bear with me as I struggle through and learn alongwith what you have to say today.

[00:01:52] Hanna Makowski: Yeah, and I’m a postdoc and I’m venturing into a new field as well. So sometimes I feel like I don’t know what I don’t know, butwe’ll get through this together.

[00:02:01] Michael Hawk: All right. You know, we’re going to talk about some of your research and what you’ve been working on, specific to the Black Rock Forest. But before we jump into that, I think there’s some background that will be important to cover. And first of all, I’d like to understand a little bit about you and how you got into the field that you’re in.

[00:02:19] What is the field? And maybe even going way back, how did you get interested in nature in the first place?

[00:02:25] Hanna Makowski: So I grew up in a suburb of Chicago very classic suburbia, you know. We had a little bit of a lawn, but not much exposure to nature. But I was always kind of drawn to flipping over rocks in my backyard. Looking for insects like around, when we’d do an Easter egg hunt and I would keep the eggs and put different foods in there and try to keep insects and I ended up killing them all, but I was running these like mini experiments in my backyard. So I always had this interest in being outside, ripping apart flowers and, you know, grass and just always felt connected to nature. And then I went on, through school went to college, was interested in biology and thought I was going to be a pre med, go into medical school. And then just decided med school wasn’t for me, as a lot of people do.

[00:03:22] You know, you have that interest in biology and everybody is like, Oh, you should be a doctor. And I did some study abroad experiences and got to see you know, more of the world and thought like, okay, there’s a lot of cool. types of plants out there. There’s so many different animals and I’m interested in like, what drives this variation that we see.

[00:03:45] I did a undergrad thesis in floral scent where I studied the floral scent differences between male and female flowers of this plant down in Florida, Canella winterana. And then I really liked doing research and wanted to keep doing it. So, that’s how I ended up in grad school and I went to the University of Virginia and worked with Laura Galloway to study plant mating system evolution.

[00:04:13] Michael Hawk: I have to ask you the floral scent research that you did, what did you find?

[00:04:18] Hanna Makowski: Yeah. so how did we get interested in floral scent in this random plant? there was a grad student who was studying this plant and he noted it started off in female phase and it switched to male phase.

[00:04:31] And he was studying the sexual phase transitions and had noted that there were different pollinators visiting the female versus the male phase. So, floral scent is used to attract pollinators and we were wondering if there were differences between the floral scent in the male and the female phase that was potentially driving the differences for the pollinator visitation differences.

[00:04:56] And we found that the male and female floral scent profiles differed within individuals. So, The males and females smelled different within a plant, but there was no consistent male or female scent across individuals which,It’s a little, speculative, but it’s probably good that there’s not a consistent male or female scent, because you want pollinators to move between the male and the female individuals of different plants and transfer that pollen.

[00:05:28] Michael Hawk: I guess the question I would havehow do you measure the scent?

[00:05:32] Hanna Makowski: it’s a technique called dynamic headspace extraction. And what you do is you have this it’s like a oven bag that people would like put turkeys in and put them in the oven. And it doesn’t have any scent to it. So you take an oven bag and you put it around the flower or whatever you’re trying to extract a scent from.

[00:05:54] And you have this little device that pulls air through it. And you capture the compounds in some neutral like, they’re these beads. I would have to pull it up from the paper for the exact methods, but basically you capture the compounds in this medium and then you can put them into a liquid media and then you run gas chromatography to identify the chemical compounds.

[00:06:22] Michael Hawk: So yeah, ultimately, okay. You’re getting to the chemical compounds that would comprise the scent. Um,I had this kind of humorous. vision of a bunch of grad students all giving subjective reviews. Yeah, which I knew that wouldn’t be the case. Like there’s no science in that, but

[00:06:40] It’s, I mean, I think it’s interesting. We just kind of a peek behind the scenes of how, you know, how do we get to understanding these relationships that exist between insects and flowers? So for digging back into Presumably several years ago, research. So anyway, I had interrupted you and you were discussing I think how that, how that led you to your next steps,

[00:07:01] , Right, I really liked research. I liked planning the experiments, and I wanted to keep doing that, and I joined Laura’s lab, Laura Galloway, where I was at UVA. University of Virginia . And I came in, had, you know, very little background and ended up kind of switching away from floral scent. In Laura’s lab, I studied plant mating system evolution, I was interested in the geographic distribution that we see of mating systems across species ranges and I studied the evolution of self fertilization, and I also studied some morphological aspects of the flowers that allowed them to self fertilize.

[00:07:43] Michael Hawk: I want to back up because you mentioned that the plants transition from a male phase to a female phase. So is this, the same plant and like for a duration of time it’s producing male flowers and then it switches over to produce female flowers later?

[00:07:58] Hanna Makowski: So this is a really cool presentations of sexual phases and sexual systems. Plants can do every and anything in terms of sex phase presentation. So the plant I’m talking about, Campanula americana, each flower is male and then female. So it has a male phase and female phase.

[00:08:22] the plant that I studied in undergrad, it had also each flower was male and then female. But it was coordinated across the whole plant, so all of the flowers were female first, and then all of the flowers were male.

[00:08:38] Michael Hawk: Wow. I have so many questions, but that’s probably for another podcast episode.

[00:08:42] Hanna Makowski: yeah, I mean, mating systems are,are I mean, there’s a reason I studied them for my dissertation, they are really cool, They’re cool to study in plants because plants have flowers, which you can manipulate pretty easily, so you can do a lot of different crosses and, like, the direct consequence of mating is the transfer of genes into the next generation.

[00:09:04] So it, it’s a really cool, a lot of biologists study sex, right? Like, we’re interested in what happens for genes getting into the next generation. So, yeah.

[00:09:16] Michael Hawk: yeah, yeah. And I admit that, yeah, a lot of my interests have progressed from non plants to now, you know, my, my plant interest is growing. so much of this is new frontiers for me. You know, I think where we’re going in this conversation is we’re going to talk about phenology and in particular you know, some work that you’ve been doing, buttell me first of all, like, how would you even define phenology?

[00:09:42] Hanna Makowski: Yeah, so can I throw a question back at you to try to do this? Okay, so. what are two things that plants, animals, they all have in common?

[00:09:55] Michael Hawk: how high level,

[00:09:57] Hanna Makowski: Yeah, well, maybe, so not like cell types or anything like that, like nothing, I don’t want to know what makes the animal kingdom and plant kingdom, like, similar, but In an organism’s life, what are two things that are common between all plants and all animals?

[00:10:16] Michael Hawk: Well, there’s definitely a process of maturing that happens over time. and I think they both eventually die. Those,those would be two things that come to mind.

[00:10:26] Hanna Makowski: Yeah, so that’s what I was getting at. they’re born, there’s a birth, a seed germinates, an egg hatches, and then there’s death, right? And hopefully, for that organism, the ideal goal is to reach reproductive maturity have offspring and contribute to next generation.

[00:10:46] But we typically have a non reproductive, immature, growing stage, and then a reproductive mature adult. And, I mean, there’s a ton of variation in what that, timeline looks like. Some organisms reproduce once in their life, some live really long times and reproduce a ton, but all organisms, go from birth until death and things happen along the way.

[00:11:15] And what phenology is, is the study of those periodic events that happen along the way Of biological life cycles, and then understanding how those events are influenced by things like seasonal changes or inter annual variations in temperature or even elevation differences. So understanding, what time period does an individual become reproductively mature?

[00:11:46] For me, I’m interested in when trees drop their leaves and when trees grow their leaves again because there are influences for carbon sequestration. in that hibernate, they mostly hibernate in the winter. And flowering happens generally when conditions are good, But yeah, so basically phenology is the study of the life cycle and how that cycle is influenced by outside factors,

[00:12:12] Michael Hawk: as you were kind of laying out that framework for what phenology is, I was thinking, you know, like, in some ways people are simplerthan plants because plants, as you point out, at least in mid latitude regions, they have to deal with freezing and snow and, you know, all these other factors.

[00:12:29] So they don’t just haveone pathway of maturing, like they mature, but then there’s periods of dormancy. And then there’s periods of drought reactivity or like other things that could totally change the process they follow. So Ican see how this is a uh, fertile, area of study to uh,really get into.

[00:12:50] Hanna Makowski: Yeah, and it’s the reason why I love studying plants. They’re stuck where they are, right? So they have to deal with what is thrown at them. they don’t have the behavioral changes that they can’t go avoid drought stress or physically move away to Florida for the winter and go back up in the spring.

[00:13:10] So, they, have unique adaptations to deal with the fact that they can’t move and I think that makes them really interesting.

[00:13:21] Michael Hawk: Very often when I think of phenology, I think of in terms of like when does a plant flower? But as you alluded to, there’s a lot of other aspects to phenology.

[00:13:30] So what are a few of the other things that biologists might look at or measure that relate to plant phenology?

[00:13:37] Hanna Makowski: Yeah, so really any part of the growth life cycle. So in a tree trees put on more bark tissue, so you can measure how much bigger the tree grows, like the diameter over a season. You could also look at the roots. Some people put these bands around the roots and see how they grow over time.

[00:13:58] Or like, you know, you could dig up roots of something and weigh the dry mass at different points and see how much it’s grown. So, leaves, leaf out, leaf fall flowers, basically, yeah, any part of the tree that’s growing you could assess when, where, and how

[00:14:19] Michael Hawk: Makes sense. And you were starting to tell me a little bit ago about a dendrometer and, you know, I think the engineering that, you know, side of my brain is, is kind of fascinated by these kind of simple tools. So can you describe for me again, how a dendrometer works?

[00:14:34] Hanna Makowski: Yeah, so a dendrometer measures tree growth. And the kind I’m using, I’m going to use two kinds. I’ve deployed one so far it’s called the point dendrometer. And what a point dendrometer does is it has a, like a plunger thing on it that is pressed up against the tree as the tree grows, it pushes the plunger back into the unit and there’s a spring on it.

[00:15:01] So, it measures how far back the plunger moved over a period of time. and that’s how much the tree grew. There are band dendrometers, which are exactly what they sound like, they are a band around the tree that as tree grows, it pushes out. So you can mark where it started and then where it ended.

[00:15:21] Michael Hawk: Kind of like a circumference

[00:15:22] differential or something?

[00:15:24] Hanna Makowski: You measure a tree with at diameter of breast height and you use DBH tapes, which just account for you know, you’re taking the circumference, but it accounts for pi, so you can get the diameter. And. Those are good, but, a slight fluctuation of where you place the tape even in the general area, it can change the accuracy.

[00:15:46] So the band endometers are a good way to get a really accurate measure of how much the tree has grown.

[00:15:52] Michael Hawk: Gotcha. And as I think about this,

[00:15:54] what do we need to understand about leaf phenology or the structure of a leaf or anything else about the leaves to kind of set us up to understand your work?

[00:16:05] Hanna Makowski: Yeah, so, leaves are like the lungs of the tree, right? That is where is happening. And they’re also where energy is being created. So, trees are large carbon stores. they hold a lot of carbon and they acquire that carbon. They sequester it through photosynthesis, which happens in the leaves.

[00:16:29]

[00:16:29] Hanna Makowski: trees are always sequestering carbon, in their bark and their roots, but they’re actively uptaking it when they have leaves on the tree. there is variation in how long leaves are on the tree, and that’s sort of what I’m interested in figuring out, what drives that variation, because that variation has implications then for tree growth and carbon sequestration.

[00:16:53] Yeah, and there’s lots of different ways that people measure phenology and think about tree leaves. So there’s global scales where you could look at satellite images and see how green an area is to determine when A season starts or a season ends.

[00:17:10] Michael Hawk: So I’m sure like, you know, everything in biology and ecology there’s just so much variance and there’s always a lot of nuance, but in general. Can you tell me a bit about what actually triggers a tree to leaf out and maybe drop its leaves later in the year?

[00:17:25] Hanna Makowski: yeah, so I don’t know if you’ve ever gone on one of those websites where you can, like, track fall and find, like, when peak fall is going to be in your area, which is nice if, you know, you’re planning to go leaf peeping or something like that. And those models take into account day length and temperature so the amount of light the tree is receiving, and then its temperature environment.

[00:17:50] And they’re pretty strong indicators of these large geographic patterns And people are working to tease them apart, because oftentimes, right, they’re, they’re connected

[00:18:01] Michael Hawk: gotcha. and I’m guessing that would, you know, some species, maybe it’s the photo period or day length is more important in that and other species, perhaps temperature is more important. There’s probably different combinations for different species.

[00:18:15] Hanna Makowski: Yes, that’s true. So there are different combinations and then There is even variation within a species. So I recently came across this cool study that was done in Fremont Cottonwood. it was Hillary Cooper, I think she’s at Northern Arizona University at the time. they did a common garden experiment where they had Individuals from populations of this Fremont cottonwood plant, or tree, from a latitudinal gradient, they grew them in the south and in the north, so you had populations from the north and the south, and then the same thing up in the north.

[00:18:59] what they found was that the southern populations seemed to be insensitive to photo period. they progressed phenologically with temperature cues, whereas the northern populationswent based off of day length their interpretation of that was that these northern populations They’ve been in an environment where they’re subject to harsher frosts that could damage them.

[00:19:27] temperature, can fluctuate a lot and change a lotday length is a pretty consistent cue. It changes, but not on a perceptible scale across years or decades even. in the south where there’s not as much frost pressure, having a cue like temperature if it’s warmer for longer, those trees can take advantage of that.

[00:19:48] Versus in the north, if it’s warmer for longer those trees won’t take advantage of that, but they also won’t get hit by an unexpected frost.

[00:19:58] Michael Hawk: kind of like a built in risk assessment that the trees have. And so in the South, it’s like, all right, the moment it warms up, I’m going to leaf out and take advantage because my risk is low. My risk of a frost and losing all these leaves is low. And in the North, it’s kind of the opposite of that.

[00:20:15] Hanna Makowski: Exactly.

[00:20:16] Yeah.

[00:20:16] Michael Hawk: that’s really fascinating.

[00:20:17] And I’ve heard of some similar sorts of, and I don’t know how, scientific these studies were, or if it’s just more kind of anecdote. But you know, certain plants and shrubs here in where I live in California will have different phenologies based on if they grew, say, on a north slope versus a south facing slope, and now, I’m curious and I want to look into this a little bit more because it sort of makes sense.

[00:20:44] Hanna Makowski: Yeah. There could be temperature differences or even like the amount of light they receive.

[00:20:49] Michael Hawk:

[00:20:49] Yeah, definitely. I guess it would probably be both in, in this case. Very interesting. So even within a single species, there’s a lot of variance and I guess that should not come as a surprise, but not something I think about very frequently. In the Fremont Cottonwood example, you mentioned it was a common garden approach. Can you explain what that is?

[00:21:06] Hanna Makowski: a common garden approach is when you take individuals from different locations and you grow them together in a garden, a common garden. And so what you can do typically is you can get Individuals from population across some sort of gradient.

[00:21:23] So this could be elevation. It could be latitude and you grow them all in a common environment and oftentimes you have multiple of these common gardens. So, if you have high mid low. Elevation, you have a low common garden that has high, mid, and low individuals, and then so on and so forth. And what this does is it allows you to separate out the effects of genetics from the environment because in those cases you’re holding the environment constant.

[00:21:51] So you can see the genetic effects of the populations from that high, mid, and low elevation and see how they respond in that common environment. A big, guiding equation that we think about when thinking about phenotypes is G by E equals P, and that’s genetics by environment equals your phenotype.

[00:22:18] So you’re varying the genetic composition of the individuals in the garden, but you’re holding that environment constant. And then that lets you see how G affects the phenotype, that genetics affects the phenotype.

[00:22:34] Michael Hawk: Okay. That makes sense. And it sounds like this is a fairly common approach to studying this.

[00:22:39] Hanna Makowski: Yeah, common gardens are common,

[00:22:41] Michael Hawk: Nice.

[00:22:43] Hanna Makowski: and they are really powerful,

[00:22:46] Michael Hawk: can you tell me a little bit about some of the applications of this type of research? Like what, you know, why would this be important, scientifically or otherwise for people to know about?

[00:22:56] Hanna Makowski: yeah, why do we care about when things happen? Besides, you know, planning our fall leaf peeping trips and fall festivals and that sort of thing. So climates are shifting we’re having earlier springs and later falls, and it’s important to know how species are going to respond to these shifts.

[00:23:19] to know whether, you know, they’re going to be able to respond or they’re going to have negative effects that impact their ability to persist. And I think this can, you know, there can be impacts that affect the individual’s ability to persist. Like, you know, if there’s a frost that kills that individual, there’s that effect that individual dies, but then that individual also is not existing in this silo.

[00:23:48] It has interactions. So understanding how these mismatches in you know, the, the life cycle timeline how shifts in seasons are going to impact that. have implications beyond just that individual and it, you can have mismatches between pollinators and the timing that the flowers come out.

[00:24:13] So if, for example, flowers are driven by day length and they don’t shift when they’re flowering, but you have an insect that is a pollinator it’s hatching is driven by temperature, you could have An early spring where that insect comes out way before that flower even flowers, and then that insect doesn’t have its food source or home, and then that flower doesn’t get its pollinator services.

[00:24:42] So there can be wide ranging effects to these mismatches Between individuals that experience, like, the effects of these shifts.

[00:24:51] Michael Hawk: Right. When you think about the system as a whole, there’s so many things dependent on each other with, you know, some sort of relationship. And I think the pollinator example is really an important one, and I imagine that there’s probably even say like, annual flowers or seasonal flowers that grow in the understory that need that early overstory to grow before the trees do leaf out.

[00:25:16] And there could be some mismatches that occur there with climate change too,

[00:25:21] Hanna Makowski: Right, yeah, like if the trees leaf out earlier and it’s now a dark canopy floor, those flowers might not do so well.

[00:25:30] Michael Hawk: right? the other thing that came to mind is how, weather fluctuates a lot. So having, you know, a season or two where there’s a mismatch, things can persist, but if it becomes year after year due to broader climate change, then yeah, that’s a different story. Maybe this is a good point to now get into the core of your work.

[00:25:52] So you’re at a place called Black Rock Forest. Can you tell me what Black Rock Forest is? Where is it? What’s it like?

[00:26:00] Hanna Makowski: Black Rock Forest is a non profit organization in the Hudson Valley. It’s in Cornwall, New York, which is about an hour north of New York City. And the goal is to The goal of Black Rock Forest is to promote research, education, and conservation. So we get a lot of school groups that come up.

[00:26:21] We have a lodge where school groups stay overnight and they go on research visits. the Black Rock Forest is a little under 4, 000 acres, so we manageinvasive species and conserve the area. the research arm of Black Rock Forest is kind of where I’m at.

[00:26:38] What’s really cool about Black Rock Forest is thatas a field station, it’s unique in that it’s not owned by a single university like most field stations are. It is managed by a consortium of over 17 institutions in New York that make decisions about how the forest is going to move forward.

[00:27:02] members from those institutions can come and do research here. We have a lot of visitors especially throughout the summer to set up their experiments. more recently BlackRock has created my position, the postdoc position. I’m the second postdoc that they’ve had. The goal for them is to start expanding their own in house research.

[00:27:25] So that’s where I come in.

[00:27:27] Michael Hawk: And then the forest itself, you mentioned it’s 4, 000 acres. Can you tell me a little bit about what the habitat looks like? What’s growing there?

[00:27:35] Hanna Makowski: Okay so Blackrock Forest is you know, a small forest, but there’s a lot of biodiversity. So we have some swampy areas it’s like a mixed eastern hardwood forest there’s a ton of red oaks, chestnut oaks and What’s unique too about this location is that we are kind of at the point where a lot of southern species were at the kind of northern most part of the southern species ranges.

[00:28:02] And then we’re at the southern part of the northern species ranges so we get an interesting mix of north and south species kind of meeting

[00:28:11] Michael Hawk: of a transition zone.

[00:28:13] Hanna Makowski: Transition zone, yeah.

[00:28:14] Michael Hawk: What specifically are you studying? What are you measuring in the forest?

[00:28:19] Hanna Makowski: Yeah, so I am interested in what underlies variation in tree leaf phenology. As I mentioned, right, we know across large landscapes that things like temperature and photo period are influencing the start of fall, the start of spring, that sort of thing, but you could be walking through a forest and see two sugar maples side by side and one has started to turn orange and the other one is still green, or one has totally leafed out and the other one has just started.

[00:28:51] And we don’t know what drives that variation. And variation at the level of a population, or intraspecific variation, is important to understand because individual organisms are what is real, right? Populations, species, these are all concepts that we put on to individuals. And individuals are the level at which natural selection acts.

[00:29:20] Individuals either live or die. So, understanding how much variation you have in individuals within a population is important for understanding if that population can persist. Like, do you have enough genetic diversity in a population for it to be able to respond to harsh selective events? Or ,

[00:29:42] Michael Hawk: so, having a lot of variation within a species. is sort of a proxy for the resilience of that species.

[00:29:49] Hanna Makowski: I think it can be, right? So if you have a population that is all the same, and there is something, that is negative, and so it affects all of those individuals in the same way, and they all die. Right, that’s bad, but if you have 50 percent of your individuals doing one thing, and 50 percent doing another, you know, if half of them die, the other half can live.

[00:30:15] So, yes, I think it can be a proxy for, like, ecosystem resilience or that species ability to persist?

[00:30:23] Michael Hawk: I’m starting to see how this all connects when you’re talking about climate change andother factors that could put a forest at risk. I see the straight line connection now with the research that you’re doing. And what is the research though? Like how are you measuring this?

[00:30:39] Hanna Makowski: Yeah, so I have tagged 550 trees across four different species of trees and those are the species I listed earlier. Those are the ones I’m familiar with. I have red oak, chestnut oak, sugar maple, and red maple. And across fall I was tracking leaf color change and drop. And then in the spring I’ve been tracking leaf out.

[00:31:01] So what that means is I go out and my 550 trees I have tagged and they’re in three different loops. So I do a loop a day. So I visit each tree every three days and I have a scale, which I categorize how colorful they are, the percentage of leaves that are still on the tree in the fall and then the leaf out progression in the spring.

[00:31:26] And then for each of these trees, I have their location and how big they are and how tall they are. And then I am currently collecting leaf tissue. So II can do DNA extractions and have genetic information. And the goal is to determine whether the phenotypic distance I see between So that’s like, if one tree has totally lost its leaves and one still has all its leaves that’s like a big distance versus if they’re doing the same thing, they don’t have a distance.

[00:31:58] I’m trying to see whether that distance is correlated with genetic distance, or if there is an environmental component to this like local micro environmental variation that is causing the variation that we see.

[00:32:13] Michael Hawk: Do you have to restrict the individuals that you use in the study to like smaller ones that you can have, you know, get better visuals on or better access to? Or is it a variety of, ages and sizes of trees?

[00:32:25] Hanna Makowski: Yeah, so my constricting factors when I was selecting these trees was they had to be on a trail because I tried going off trail and it just took too long. I wasn’t going to get the sample size that I needed, so they had to be on a trail,

[00:32:39] Michael Hawk: Very practical restriction. Yeah.

[00:32:42] Hanna Makowski: and then I had to be able to reasonably, like, assess their canopy without spending an hour trying to, you know, visualize because I was seeing a couple hundred trees each day.

[00:32:54] So, was trying to get trees of generally the same size to control for that. I did measure them. So I have that. That I can include as like a correlate in my model. But yeah, I was trying to get also trees that were in the canopy. I didn’t want to have understory trees in my assessment.

[00:33:12] Michael Hawk: I could imagine an understory tree. There’d be another set of variables at play if those were included. Yeah. Maybe this is. Off topic. And if you don’t want to talk about it, you don’t have to, but you mentioned earlier that you had a bruised rib from shooting leaves, like what’s up with that?

[00:33:29] Hanna Makowski: Yeah. the thing about working with trees, right, is that you have to look up at them. So my neck hurts. And then if you want leaf tissue, you can’t just snip it off. Some of my trees I have been using a pole cutter, but to get leaf tissue for extractions I have had to use a method called shotgun sampling, which you use a shotgun to shoot down a branch

[00:33:52] of the tree so you can get leaves. And I went through training to, you know, learn all the safety protocols. And I have been going around Black Rock Forest for the past two weeks with a shotgun in tow and shooting down branches so I can collect leaf tissue. So my shoulder is feeling a little rough, but It will, all be worth it once I get the extractions going and get the data back.

[00:34:17]

[00:34:17] Michael Hawk: Yeah. Something that I think the average person wouldn’t think about when it comes to being A forest biologist or what would be the label that you would put on it?

[00:34:27] Hanna Makowski: you could call me a forest biologist. in all my job applications on my CV, I call myself an evolutionary ecologist. it’s not something you would typically expect. I mean, if you work with trees, you would maybe expect it. An alternative method is to use, like, a canopy lift which is possible if your trees are near the road, but, you know, I’m deep in the woods, so, the shotgun is the simplest way to do that.

[00:34:57] Michael Hawk: And I know that you’ve been hard at work. Uh, It’s been field season. So are all of your trees fully leafed out or you still have measurements you’re collecting right now? It’sfor reference, it’s May 20th when we’re having this discussion.

[00:35:09] Hanna Makowski: Yeah, so all of my trees have fully leafed out. I stopped about a week ago doing my loops. And all my trees were fully leafed out. Some of them hadn’t fully expanded to their summer condition yet but I caught peak variation and I had to prioritize getting the leaf tissue, so I figured it was time to call it on my eight mile a day loops.

[00:35:35] Yeah, so leaves are fully out and it looks like in fully summer condition. So, I do a scale of zero to four and I would say all my trees are a four right now.

[00:35:45] Michael Hawk: Gotcha. So, it’s a work in progress, I know, but do you have any preliminary insights based on the data that you have collected?

[00:35:54] Hanna Makowski: Yeah, I do. Definitely from the fall. So I have all that data entered and I’ve looked at it. I am waiting for genetic data, so I haven’t been able to answer my big genetic versus environment

[00:36:06] question.

[00:36:07] Michael Hawk: I can imagine that will take

[00:36:08] some time.

[00:36:08] Hanna Makowski: Yeah, yeah, so in the fall What was really interesting was, one, there is variation, so that is satisfying.

[00:36:16] You know, you have these moments where you walk through the woods and you see these things, but when you aren’t collecting data, it’s all anecdotal until it’s in my Excel file. And I think what was interesting was that there is variation within species and then when looking across species I see variation in the amount of variation.

[00:36:40] So, my red oaks, they had less variation. They were kind of all more similar to each other and doing things at the same time, versus my sugar maples. There were trees that were totally green while others had started to lose leaves. So the amount of variation that we’re seeing is variable across species.

[00:37:03] And I think, this could be a couple of things. It could be that the red oaks are maybe More photoperiod driven, if they’re all doing the same thing at the same time. They could have less genetic variation than the sugar maples. So I am excited to get those sequences and see sort of how much genetic variation is there in all of my species.

[00:37:27] And does amount of genetic variation correlate with amount of phenotypic variation. And then for the springall of my data still needs to be entered. But it looks like spring is shorter. it happened a lot faster and it seemed less variable.

[00:37:45] So trees were kind of leafing out at similar times. And that would be consistent with what’s in the literature. Generally, spring tends to be a little bit more consistent.

[00:37:55] Michael Hawk: so interesting to hear you say that because I’m also thinking about how that tracks like, say, totally different and probably unrelated, but it’s still interesting. And I feel like I need to say it like bird migration you know, spring migration is much more focused and, and similar periods of time.

[00:38:12] Fall migration is more diffuse and spread out and more variability in there. And I suppose that tracks with, I mean, the plants are, this is just me totally pontificating, but you know, plants are the foundation of the food web that say birds need. So, sorta makes sense if you kind of squint and, you know, think about it that way, but it’s, it’s an interesting correlation anyway.

[00:38:37] Hanna Makowski: yeah. And one thing I was wondering, too, is that, I don’t know if this connects with the birds but for the spring, these trees, they’re dormant, right? well, conditions can vary, You know, based off of their microenvironment, if you’re in a wetter area, it might be your roots are colder because there’s more water retaining cold, getting to lower temperatures or something, but the trees are dormant.

[00:39:05] So, like, springing out of dormancy. seems a little bit different than like the winding down, the summer and the fall, you’re accumulating so many differences while you’re actively growing like the effect of the differences in the environment might be, you know, stronger at the end of the season than at the start of the season after you’ve kind of like, maybe reset in the winter.

[00:39:31] I don’t know how valid that is. But I like wonder how variable winter conditions are for these trees if they are not actively

[00:39:41] growing.

[00:39:42] Michael Hawk: Yeah. Another level to consider altogether. you had mentioned at one point in time when we were talking about something I wrote down is the leaf economic spectrum. And I wasn’t exactly sure where the best place to wedge that into our conversation would be, but maybe now since I brought it up.

[00:40:00] Hanna Makowski: Yeah. So the leaf economic spectrum is this global pattern of leaf lifespan and photosynthetic rate. So the economic spectrum idea comes from the fact that, a leaf costs carbon to make. the tree has to produce this leaf, it has to grow it, so it has an energy investment that is put into And ideally, it will get at least that amount of carbon.

[00:40:32] back, hopefully more, so it can grow. So it needs to, net zero or have a benefit. the idea is that you have leaves that have short lifespans, they have to have a high level of respiration, they have to sequester or create carbon, photosynthesize a lot really fast to make up for the energy that it took to make that leaf versus a leaf that sits around for a really long time it probably had more investment.

[00:41:06] And like, if it’s a thicker leaf or something like that, it can respire at a lower rate because it sticks around for longer to make up for that carbon investment that went into the leaf. something that I’m wondering is, I have these early fall trees, and I have trees that, had their leaves for a really long time, and I’m wondering if this pattern that we see across global scales could also explain what’s going on at a local level.

[00:41:37] So, do my early senescent trees have a higher rate of photosynthesis? Did they sort of meet their carbon credits early enough where they could drop their leaves? Compared to a tree that holds on to its leaves for longer, maybe it has a lower photosynthetic rate. I don’t know if this operates at the level that I’m looking at here in like a population cause we’re thinking sometime in the scale of like a week or two.

[00:42:08] And I don’t know if we’ll see that, but that is one thing that I am piloting this upcoming summer. I’m going to be looking at my earliest trees versus my latest trees and assessing their photosynthetic rate. To see if there’s any differences and you know, the way in which they photosynthesize, the rate at which they do that.

[00:42:28] Michael Hawk: So is, is then the leaf economic spectrum example that you gave, is that most noticeable, like in an evergreen tree, for example, compared to a deciduous tree like a live oak versus a red oak or something like that.

[00:42:44] Hanna Makowski: Yeah, it takes, it’s likethousands of plants that they’ve analyzed kind of like the length of that they hold on to leaves versus their photosynthetic rate. So I think you’d see that in something that’s always green versus something that loses their leaves. Yeah, so I don’t know if that scale will hold.

[00:43:00] I think it’s interesting to see if these, larger patterns hold true at smaller scales. And I think connecting scales is really important. For our understanding of, how, you know, how things work, like, does what happens at the local level always translate up? And what we see as, these broad macro patterns, can we see that on a local level?

[00:43:24] Michael Hawk: Yeah, I can imagine that in the earlier context of say, you know, climate change as an example a couple of weeks difference then amplified by some of these other patterns that may be revealed from your research could really clue you in into some other things.

[00:43:40] It’s as I stumble over my words, but you know, we talked about some of the applications before generally with respect to like understanding how climate might affect, some of these trees and which ones might be better suited and things like that. But that could translate into things likeevolutionary rescue or assisted migration or other factors that I know you also have an interest in.

[00:44:01] So maybe you can tell me a little bit about some of these other applications to this research.

[00:44:06] Hanna Makowski: Yeah, so I’m working right now in a single population um, but, It’s important to understand the context of a species distribution and think about your population in the broader range of your species. So in Eastern North America, 000 years ago, there was a glaciation.

[00:44:28] So there’s a lot of ice covering the northern part of the Eastern U. S. and not a great place for plants to live. So where were plants? Plants were in the south in glacial refugia. And as those glaciers receded, we have expansion from that glacial refugia of seeds, acorns, right? They’re making their way more north and they’re establishing a new habitat and now we have what we would consider the modern species range.

[00:44:56] And With that expansion, you have serial bottlenecks happening. So an individual from a population makes it to a new place and establishes, and then that population expands, and then you get another expansion. And with that expansion, you have a decrease in genetic diversity. So generally, we expect higher genetic diversity in the south of species ranges, at least in the eastern United States compared to the north.

[00:45:26] what this means is thatpopulations at the northern range edge, where they’re expanding, they have potentially low genetic diversity, which means they may not be able to adapt to changes well. So, with climate change changing suitable habitat for species what we’re seeing in a lot of species is that the south is becoming uninhabitable, things are getting warmer in the north, the suitable conditions are shifting northwards.

[00:46:02] And the question remains whether those northern populations are going to be able to respond to this new warm habitat. Will they be able to continue to expand? So, evolutionary rescue assisted migration, these are all concepts moving individuals from higher genetically diverse populations, and on the eastern U.

[00:46:26] S. that would potentially be the south, and adding those individuals to populations or putting those individuals into new environments where. The habitat is becoming more suitable and seeing how, that impacts the species ability to persist and to continue expanding. Yeah, so I think, the first step is, you know, I’m doing this at the level of a population, and I have plans to work with collaborators to expand it, and the goal is to understand how genetic diversity is structured across

[00:46:58] a species range and understand what that means for a species ability to persist and respond to habitat changes because If we find out that low genetic diversity is bad and they can’t respond, then maybe we do need to facilitate, their expansion or use more Southern species to help out the Northern populations.

[00:47:24] Michael Hawk: This seems really interesting to me just simply from the fact that you can’t really do an experiment on a timescale of hundreds or thousands of years. You have to really extrapolate here to you know, to try to assess how things might play out.

[00:47:40] And that’s, that’s, I guess what you’re doing.

[00:47:43] Hanna Makowski: Yeah. And I, I mean, I think I’m a little bit, like, I don’t know, my research. Right now is like establishing those natural genetic diversity patterns. I do know there are people who are doing specifically evolutionary rescue experiments. Like, the work I’m familiar with is in a guppy population.

[00:48:05] In, I think it’s in Brazil. I’d have to read the paper again to check, but it’s by Sarah Fitzpatrick at Michigan State. She, there was this guppy population and she moved. individuals from upstream where, you know, there was a lot of genetic diversity where the native population was, to two different sites downstream that had small population sizes, weren’t doing too well, didn’t have a ton of genetic diversity.

[00:48:37] And they sequenced all those populations before they added individuals. They knew what they were adding in terms of Like the genotypes and then they tracked what happened after they added these individuals, I think, out for like eight generations or maybe longer, but they wanted to see what happens when you put in new individuals.

[00:49:00] Do they swamp out the natural population that’s there? How do they mix in? Are they like, causing harm? Are they bringing in bad, like, is there locally adapted genes there that we’re swamping out with the new gene flow? And I think that work is really cool. And when you work with something that reproduces on a shorter timescale than, like, a tree I think you can get that can apply to trees.

[00:49:32] So yeah, I think that there are people who are doing those experiments. And hopefully I’ll be, characterizing the variation that we do see and alongside of these other experiments. And then I’ll be able to, like, pull from some of those model systems and see, we can combine sort of these different, you know, Experiments and say, okay, now if we want to do

[00:49:53] These types of things in trees, if we want to restore a northern population, how should we do it? Let’s look at the guppies or let’s look at the fruit flies or something like that as good examples of actually tested evolutionary rescue.

[00:50:08] Michael Hawk: Interesting.

[00:50:09] Okay, Hannah, this has really been thought provoking and there’s a lot of things I’d like to follow up on some, threads to pull and look into. And I can only dream that I’ll have enough time to investigate all the fascinating things that you mentioned.

[00:50:22] But you know, it is wrap up time. So, I always like to ask from a small pool of questions you know, some standard questions anyway. And one of them is, what, what’s something, you know, practical. that say maybe listeners could do to help prevent or maybe that’s blocking them or hindering them from taking action to support biodiversity.

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