Music Plays (Dust by Tyler Fruik)

Gabe Nyen: Hey, welcome back to ASCCing the experts – a
podcast where I speak with natural resource scientists and managers about where
their work intersects with climate adaptation and applied ecosystem management.
If you’re tuning back in, welcome to the first episode of season 2, I’m your
host, Gabe Nyen. And here’s the episode.

Gabe Nyen: We’re here today with Dr. Steven Brantley. He’s
an associate scientist at the Jones Center at Ichauway. He’s been at the center
since 2014. Thank you for joining for a second take today. I always find it
both interesting and enjoyable to get to talk with you.

Dr. Steven Brantley: Thank you.

Gabe Nyen: So, I’m curious, and I’m sure other folks are
too, how did you get to this point? Where were you at in your career and tell
me about the history of your story as a researcher and how you got involved in
the research you do right now?

Dr. Steven Brantley: So, I started off as a biology major at
Virginia Commonwealth University. Kind of wanted as an undergraduate to go into
ornithology, but had an epiphany at some point my senior year that I really
liked plants and plant physiology, and pursued that at VCU through my PhD and
even a short postdoc there. I then spent four years as a postdoc at Coweeta
Hydrologic Lab, where I really shifted gears into thinking more and more and more
about water, and how water moves through ecosystems. And then, after some time
there, I came to the Jones Center as an assistant scientist, and I’ve been here
now almost 12 years.

Gabe Nyen: So you started off ornithology and ended up in
this. What did that feel like as a pivot?

Dr. Steven Brantley: It felt good because, honestly, a lot
of the ornithology research that was going on in my school at the time I just
found incredibly boring.

Gabe Nyen: Like what?

Dr. Steven Brantley: A lot of demographic work and data that
it takes 30 years to see sort of the, you know, the outcome of, and being able
to go out in the field with a gas exchange system and put it on the plant and
know what the plant’s doing in about 10 minutes is a lot more fun to me.

Gabe Nyen: And that’s what you get to do right now?

Dr. Steven Brantley: And I still, yeah, and I still get to
see the birds.

Gabe Nyen: Well, that’s good.

Gabe Nyen: So, what’s been the like coolest or most fun
moments of your scientific career so far?

Dr. Steven Brantley: I’m kind of going to go back a ways.

Gabe Nyen: Back to ornithology?

Dr. Steven Brantley: No, not that far back, but back to
Coweeta. So I did spend four years there, and I really got to explore long-term
data sets there. And it was just really rewarding to me that someone had put
that much effort in for almost 80 years at the point I was there. So I got to
personally work with data from the 1930s all the way up through the 2010s. And
that was, that was cool. And so there were things about Coweeta that I liked,
things about it there that I wanted to keep doing, things about what I was
doing there that I was able to transfer to the Jones Center, certainly, but
just being able to work with that long-term data, it really has driven how I
see my job here. I want to build a similar legacy here at the Jones Center.

Gabe Nyen: And for folks that don’t know about the legacy of
Coweeta, can you take a second and describe what that experimental site is?

Dr. Steven Brantley: Sure. It’s in Western North Carolina,
and it’s a watershed-based experimental forest, and it’s actually a natural
laboratory, as designation. And the basin, Coweeta Basin, is about 5,000 acres,
and it’s split into about 14 experimental watersheds where over time they did
different treatments, different types of logging treatments or farming
treatments, species conversions, and measured the response at stream scales.
So, how much water is coming off the landscape, what the quality of it is. So
it’s got a real legacy in the forest hydrology community.

Gabe Nyen: Cool. I took a forest hydrology course, and the
word Coweeta came up, I swear, every other sentence. And I just see so many
parallels being drawn back to it.

Dr. Steven Brantley: Yeah, and there’s a lot of linkages
between Coweeta and the Jones Center in terms of people moving back and forth,
and the director, the first director that was here for 25 years was a scientist
at Coweeta, and some of our other scientists have also worked there. So there
are a lot of historical linkages between the two places.

Gabe Nyen: Yeah, cool.

Gabe Nyen: So I’m also curious about the coolest or most
exciting experiment that you’ve gotten to be a part of. Can you tell me about
that? Does any come to mind?

Dr. Steven Brantley: Uh, you know, I’m going to have a
little bit of recency bias here. We published a paper a couple of years ago in
Ecological Monographs where we looked in detail at the entire water budget of
longleaf pine, and we did a little bit of everything. We did ground cover
physiology, tree-level sap flux, we did throughfall and interception in the
canopy and sub-canopy, and we even did some modeling of litter and how much water
that consumes. So a lot of things that I learned at Coweeta, but I’ve
translated here, and that was a long project. We had six years worth of data, a
lot of different data sets, and we finally got it published.

Gabe Nyen: Cool. I have read that paper, and I did like it.

Dr. Steven Brantley: It’s a there’s a lot to digest in it.
So just the methods alone I think should make it last.

Gabe Nyen: So it sounds like you have an expansive research
interest within the ecosystem, and things that you feel comfortable or are
excited to look into. What keeps you excited to continue research in this
field?

Dr. Steven Brantley: Uh, what keeps me excited is that the
need for water is not going to go away, and the demands on water are not
getting any smaller. We just heard about locally, some local issues that have
come to light recently about data centers and water usage. Um, you know, water
is one of the keys to life, and that’s not going to change anytime soon, and
the way we manage land affects the water supply. So, um, that’s really the
angle of all my research, that’s where I’m coming at it from.

Gabe Nyen: Is water supply?

Dr. Steven Brantley: Water supply, yeah.

Gabe Nyen: So, to talk about water supply, full
transparency, this is our second take of recording this, and the entire time
that we were having our initial conversation, I was just shocked at the scale of
things that you were talking about. I would ask a question about the forest,
and I’d hear a response about a landscape, including agriculture and
surrounding areas. So, when we talk about water, when we talk about water use,
forest water use, what scale do you automatically go to thinking of?

Dr. Steven Brantley: Wow. Um, I mean, the watershed is sort
of the default because that’s where, uh, that’s the ultimate scale that
produces the water for, for people or for ecosystems. Um, but because of my, my
training in graduate school, you know, I, I start off often times thinking
about the leaf scale, and everything at the leaf scale scales up to the
watershed. Things that are happening at the, the interface between the leaf
surface, the stomates, and the atmosphere, and how that leaf of that particular
species is responding to the weather that day is going to eventually scale up
to the whole watershed. And it gets complex, but, um, that’s kind of how my mind
works is making the linkages between those two scales.

Gabe Nyen: Okay, so when, when someone asks a question about
a tree or a landscape, do you traverse all of the different scales in your head
and like link them all together to answer that question? How do you jump to
talking about a scale?

Dr. Steven Brantley: It depends on where the variations are.
So, are the variations amongst, you know, a forest versus an ag field, or
different types of ag fields, you know, corn versus peanuts, or are the
differences more subtle than that? Are they at a smaller scale? Is it a C4
ground cover grass, or is it a shrub that’s come in because you haven’t had
fire on the landscape recently? So, it just depends on where I think the
variation is that’s going to affect that outcome at the watershed.

Gabe Nyen: Yeah. So I’m stuttering because that’s super
complex, and I think it’s so cool that you’re answering all these questions
thinking about all of those different interactions from big to small across a
landscape.

Dr. Steven Brantley: Yeah, the complexity is a big part of
it. Um, I actually took a great course in graduate school called Biological
Complexity, where we talked about complex systems, what they are, how they
evolve, and, uh, I think that really set, uh, set me on this course to, to try
to look at complexity, see how it scales from small to large. Of course, it
gets exponentially larger as you go up in scale, but it’s pretty complex even
at the leaf scale. Um, but it makes it fun, it keeps me in business, and, um,
yeah, it’s, it’s really rewarding to be able to, to think about all these
things working simultaneously. Now, you know, with all that said, there’s some,
some solace in the fact that all that complexity, you know, it has bounds. So a
leaf’s only going to use so much water a day or so little water a day, and, and
so you can normalize things, and everything, it fits within distributions, and
analytically, you learn how to kind of deal with that complexity in that way.

Gabe Nyen: Yeah. Wow. The, what’s coming up for me is that
during my comprehensive exams, I was assigned a couple papers on pattern
process, scale, complex systems, and that really felt like a new exploration
that I hadn’t ever taken a class in or been guided through thought. And so I
really read into that and the pattern process complex systems, and organizing
groups of other PhD students and candidates to read papers and discuss those
things, just constantly felt like my brain was being twisted in a direction it
doesn’t go frequently, and I really enjoyed it.

Dr. Steven Brantley: That’s good, that’s a good exercise. We
need to challenge ourselves. We really need to challenge ourselves. Um, I’m,
I’m sort of an anti-silo scientist. Okay. I mean, I, I still look at things
from that leaf-level physiology mindset, but I’m open to considering that
that’s not the whole world.

Gabe Nyen: Anti-silo scientist. Does it say that on your
door?

Dr. Steven Brantley: No, but it should.

Gabe Nyen: So if we were to zoom out onto the, the, the
person scale, what are some ways that you think that everyday folks interested
in forestry can become more, more invested and more knowledgeable about water
use interactions on the landscape and forests and things like that?

Dr. Steven Brantley: Yeah, I think it’s even broader than
the water use question, although I think the water tradeoff, I think that’s the
key term. Everything is a tradeoff. And so if you’re coming into forestry
thinking about nothing but production, realize that that production, you know,
producing more fiber or producing, sequestering more carbon is going to come
with a tradeoff of some, some type. And oftentimes, you know, if you’re talking
about just product, production forestry, that tradeoff might be water. Often
times it is water. That might be okay in some ecosystems. In some ecosystems,
that might cause a little bit more stress. Forests can use a tremendous amount
of water. So I think just more generally though, we need to realize that there
are tradeoffs to everything in life, you know, in science, in the different
silos that you find yourself in, and, and one of the, one of the sort of key
figures that I’ve interacted with since I’ve been at Jones Center was, was
Jerry Franklin, famous forester from Washington State, and he, he said, you
know, anytime you try to maximize one thing, you’re going to lose something
else. And so the idea that I like from the longleaf ecosystem is that we can
optimize multiple things without losing out on any one thing. And so, that’s,
that’s where that sort of framework of understanding tradeoffs comes into my
science.

Gabe Nyen: Yeah. So meandering more into longleaf, and some
tradeoffs into the future, what are some tradeoffs that you see about having
longleaf on the landscape as opposed to other forest species? How could it
benefit the landscape?

Dr. Steven Brantley: Sure, I mean, I’ll start off with sort
of the downside of longleaf. Is one, it’s it’s not a super fast growing,
productive forest like say a loblolly plantation. Those are all over the
Southeast, they’re important for fiber production, they’re important for building
materials. Longleaf, you get something different. You get a higher quality
wood, but it takes a long time to get there. And, and I think that’s where a
lot of people struggle, and I think that’s why longleaf is not more common. You
know, you might not get a usable tree for 80 years. Well, that’s beyond the
lifespan of a lot of people, whereas, you know, if you’re an investment
forester, you can get a loblolly to grow in then 25 or 30 years. So I think
that’s probably the biggest limitation of longleaf. But what you get in return
is more water on the landscape, you get amazing wildlife habitat, you get
amazing biodiversity, you get a very resilient ecosystem in terms of being
naturally resistant to fire and insects and storms, and so, so it’s, it’s a,
again, it’s a tradeoff. You’re trading off an immediate or at least somewhat
short-term return perceived for something that’s long term. Yeah, and I can see
that you don’t totally agree with that perception, but that’s okay, I’d love to
hear more about that.

Gabe Nyen: And that’s okay. With all of these tradeoffs, we
have these long-term perceptions of what we’re expecting to happen into the
future. And if we’re thinking about all these different balancing acts going
into the long term, we’re also thinking about all the short-term balancing acts
that would happen if we were to manage a quicker rotational species. And so
that was just the the 80 years versus 30 years cut and dry just kind of made me
made me think about all the huge amount of tradeoffs that we have in the
landscape, which you spoke about. And I think that remembering all those tradeoffs,
like you said, is the really important part.

Dr. Steven Brantley: Right.

Gabe Nyen: And so, you know, I love longleaf. Obviously, you
work in the longleaf ecosystem, and there’s something beautiful and charismatic
about it. It’s not right for every piece of property in the Southeast.

Dr. Steven Brantley: For sure. And it can be expensive to
maintain. You know, there’s a lot of effort that goes into it. That’s probably
the other the other thing that you have to consider. But, you know, for a
motivated landowner, it’s it’s the right call a lot of times.

Dr. Steven Brantley: Not everyone wants that, but, you know,
we we want to we want to promote it as much as we can.

Gabe Nyen: So let me pivot for one second and talk about
different local climate change projections into the Southeast. What are these
projections, and how has your work looked into some things over the past
period, and what are some thoughts moving forward?

Dr. Steven Brantley: Yeah, I think the projections, I don’t
know if I would call them projections anymore because they seem to be coming
true every year. Longer growing seasons, we definitely see more hotter temperatures
on the shoulder seasons, so late growing season, November, December, early
growing season, so growing season’s getting longer. It’s not necessarily
getting hotter every day, but there are there are some complexities going on
there, too. But probably the biggest thing is that droughts are getting more
severe, even the shorter droughts. You know, we went in 2016 or 17, I forget,
we went 72 days with no rainfall on on Jones Center.

Dr. Steven Brantley: That certainly had an effect on ecosystems.
And then when we do get rain, it’s it comes all at once. You know, in this past
May, we were coming out of a drought from August where we we were pushing, you
know, we thought we were pushing into a long-term drought, and then in May, we
got 20 inches of rainfall out of an annual average of 50 inches. So, it’s the
swings are getting wilder in the weather, and that’s not a projection. That’s
it was a projection 5 years ago, it’s reality now. And so those are the kind of
things that that the ecosystems are dealing with. I mean, the trees are stuck
out there, right? They have to deal with the conditions that they get, and so
it’s either going to be really dry, or then it’s going to be really wet. And I
think that’s that’s that’s the big thing that we have to think about the next
50 years.

Gabe Nyen: Yeah, and what are your research questions
surrounding that change?

Dr. Steven Brantley: Uh, so one one really cool experiment
that we did,

Gabe Nyen: I’m excited to hear about it.

Dr. Steven Brantley: And we in some ways we failed at it. We
wanted to see how long it would take to kill longleaf pine seedlings from
drought. And these are naturally regenerated seedlings, so a little bit
different than seedlings that are put in during a reforestation restoration
project.

Dr. Steven Brantley: And so we covered them with shelters to
exclude not just like 30% or 50% of rainfall, but we excluded 100% of rainfall.
And basically, what we wanted to do was monitor the physiology biweekly until
they died.

Dr. Steven Brantley: Okay, and so we went through the the
growing season, we started in June, we went through October, all the longleaf
were still alive.

Dr. Steven Brantley: All the seedlings were still alive.

Dr. Steven Brantley: And then we we uh stopped doing the
physiology. Um, there was a little bit of a change in the sheltered seedlings
versus our control seedlings that were right nearby, but but receiving normal
rainfall. And then we let the shelters sit just to see how long it would take
to kill those seedlings. Well, then we had to go back and and remove those
shelters before the next prescribe fire. Seedlings were all still alive.

Dr. Steven Brantley: And we went back out a few years later,
actually this last year, and they’re all still still alive, and they’ve all
rocketed. So these are seedlings, longleaf seedlings, that went a year without
receiving precipitation. And, uh, uh, I lost what the original question was,
but those are the kind of things that I want to know how these species are
responding. And the way these longleaf survived is they have very deep
taproots. So, um, to me what this means is that yeah, these, these trees are susceptible
to drought , they are not going to grow that year. Um like the control
seedlings did, but those are the potentially the kind of droughts were going to
see, like months without precipitation in the summer. And longleaf persevere,
at least in that case, which is really cool to see. So some other things were
doing: were monitoring sap flux on larger trees to see how they respond to
these long periods of no rain. But that seedling experiment was really one were
proud of and one were still trying to get published.

Gabe Nyen: Cool, well I’m still interested in hearing more
about it. I have one more question that is still coming up for me and it’s on hydraulic
redistribution. The ecosystem is complex, and you’re talking about a tap root,
and I also know about the roots that go outward near the base of the tree near
the topsoil. How might the dynamics of hydraulic redistribution happen within
this ecosystem and how might they affect the seedlings that we’re talking about
right now?

Dr. Steven Brantley: So that’s a really timely question
because we just published a paper on root exclusion. In the rainfall exclusion
paper, we did trench around half the plots so there was no hydraulic redistribution
helping out the sheltered seedlings, so they were all getting water from at
least a meter deep or deeper. In certain circumstances hydraulic redistribution,
again that’s water that’s coming up from deeper, wetter soil layers to shallow soil
layers through tree roots, and being released through the soil. Under very dry conditions,
it can help seedlings and grasses and forbs that are coexisting with longleaf
get through a drought. So it’s a facilitative effect. The paper that we
published yesterday showed that under wetter conditions, excluding longleaf roots
actually helped the groundcover species be more productive. So there’s this shift
from competition to facilitation depending on climate which is really cool. So under
wet conditions, yeah longleaf is competing for surface water. Under dry
conditions it goes deep and it helps the species on the surface survive a little
better. But you know, one thing that we have to get away from is that thinking
about all these species in human terms. They are all just out there just trying
to survive. Some of these patterns that we see are definitely not intentional.
I don’t think that longleaf is trying to help the groundcover survive. It’s
just trying to be the most efficient in the way its using water. But under
severe drought, it can definitely have a positive facilitate effect on the groundcover.

Gabe Nyen: Is this an osmotic gradient? What do you think
the underlying distribution factor is?

Dr. Steven Brantley: It’s a water potential gradient. From deeper
soil that never goes below a certain threshold of water and if a patch of
surface soil gets really dry. We haven’t really determined what that threshold
is yet. Its highly dependent on the soil. In the soils were working in, its
really sandy. The volumetric water content would get down to about 3%, and that
seemed to be when the hydrologic redistribution would kick in. That water
subsidy from redistribution would help alleviate some of the water stress in
some of those groundcover species at least during the first experiment. I will
just clarify for folks out there that these trees are rooted down to 11 or 12 meters.
At least that is the theory, we have never dug one of them up. But our isotopic
data shows that they are using groundwater, and we know how deep the groundwater
is so yeah. A lot of dynamics in the ecosystem. Every time you think you have
your story strait something changes. You get new data.

Gabe Nyen: Well Dr. Steven Brantley, I have so very much appreciated
our conversation today. I thought it was super enjoyable and I’m really excited
for a lot of folks to be able to listen and interact with this.

Steven Brantley: Well thank you very much for inviting me. I
hope folks got something out of this. And feel free to reach out.

Music Plays (Dust by Tyler Fruik)

Gabe Nyen: “Thanks again for joining for the start of season
two. The previous host, Rylee, passed this project on to me upon starting a new
position as an ORISE Fellow with the Forest Service and the NIACS team. In
leaving, she wants you all to know that she really enjoyed putting together the
season one content, and thanks you for all your engagement! She’s super excited
to see how the podcast evolves with me (Gabe) as the host and is looking
forward to being a first-time listener. This podcast is rooted within the
Adaptive Silviculture for climate change study – a collaborative effort to
establish a series of experimental silvicultural trials across different forest
ecosystems in the United States and Canada. Until next time, cheers y’all.”

Music Plays (Dust by Tyler Fruik)

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