People, Fire and Global Biome Divergence in the 21st Century

Rheinhardt Scholtz, Department of Agronomy and Horticulture, University of Nebraska-Lincoln Author

02/24/2021 Added

7 Plays

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In the 21st century, we find ourselves faced with uncertainty in managing our terrestrial ecosystems. In fact, our planet faces major anthropogenic threats to the functioning of many ecosystems. This talk covers how society and the age of information can better conserve our landscapes.

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[00:00:00.800]The following presentation is part
[00:00:02.720]of the Agronomy and Horticulture Seminar Series,
[00:00:05.870]at the University of Nebraska-Lincoln.
[00:00:08.632]Rheinhardt Scholtz is a Post-Doc
[00:00:10.700]in the department.
[00:00:11.830]He is originally from South Africa.
[00:00:14.070]Got his first degrees from there
[00:00:18.130]and then now he is been here for,
[00:00:22.500]I don't even know how long.
[00:00:23.333]You were at Oklahoma State for a while,
[00:00:24.850]where were you before then?
[00:00:26.270]Yeah, before Oklahoma State,
[00:00:29.240]I was sitting in South Africa.
[00:00:30.700]I was working at South African National Parks
[00:00:32.500]while doing PhD, yeah.
[00:00:33.950]So his first foray into the North America
[00:00:37.400]was in the Great Plains, so.
[00:00:39.560]And he has done work and published
[00:00:41.050]in biological conservation landscape ecology
[00:00:43.870]with breeding birds, with fire,
[00:00:45.560]with landscape use and change,
[00:00:46.940]so he's quite the landscape ecologist as well.
[00:00:49.490]So, I'll go ahead and let Reinhardt start talking.
[00:00:54.100]Thanks, Caleb.
[00:00:55.620]Well, thanks again.
[00:00:57.380]So I'd like to start off with acknowledging
[00:00:58.800]some of the important components that have enabled
[00:01:01.300]some of this research that I'll share with you today
[00:01:04.050]such as the Holland Computing Center.
[00:01:06.240]Sam Fuhlendorf and Steve Archer who have been instrumental
[00:01:08.340]in some of the initial conversations
[00:01:09.970]and the National Science Foundation that funds my research.
[00:01:14.210]So this talk will kind of segue between these four points.
[00:01:21.410]There might be here in there me sneaking off
[00:01:24.130]and going on a little bit of a tangent here and there,
[00:01:26.360]but I guess we were allowed to
[00:01:28.710]it's a kind of a weird period of time nowadays, yeah.
[00:01:32.090]But what's brought us a little bit closer nowadays
[00:01:36.620]I think is this we in middle of a pandemic
[00:01:38.680]we find ourselves in now.
[00:01:40.320]We've been instructed to go out to nature
[00:01:42.550]and go an experience, go for a walk.
[00:01:45.110]And I think of that as someone that's,
[00:01:49.710]well, speaking to the choir here for sure
[00:01:51.830]but we all conservation minded
[00:01:53.380]and we have those connections.
[00:01:55.090]But more often than not when I think about keeping those,
[00:01:59.340]separating people from nature,
[00:02:01.600]I often think about natural landscapes
[00:02:03.760]that are being turned down to become sort of monocultures.
[00:02:05.810]So we had this heterogeneous landscape
[00:02:08.170]that had some sort of biodiversity attached to it.
[00:02:11.650]We convert it to something else that is generally ups
[00:02:15.540]to what it was before.
[00:02:16.760]And often, most times we don't really know
[00:02:19.280]what that means for biodiversity but such is life.
[00:02:22.840]But what we really wanna think about is this,
[00:02:24.383]what is this?
[00:02:25.216]This is what I'm thinking about
[00:02:26.250]when I'm thinking about enjoying these landscapes.
[00:02:29.760]Not thinking about what it means for biodiversity
[00:02:31.900]when we destroy them but more how can I enjoy it?
[00:02:34.910]And I know we all have these experiences
[00:02:36.620]and that's really what I should be thinking about
[00:02:39.530]when I think about how it's becoming difficult
[00:02:42.220]to separate people from nature.
[00:02:44.970]But we are approaching seven, eight billion people
[00:02:48.410]on this planet, never been seen before.
[00:02:50.830]Our society has grown in pretty much every aspect of life.
[00:02:55.210]Enormous Ag farms of course, replacing natural areas.
[00:02:58.070]Medicines better, we live longer,
[00:02:59.770]we need to feed longer.
[00:03:01.740]We need places to live.
[00:03:03.050]Urban areas are expanding and they generally don't expand
[00:03:06.390]at the cost of other areas.
[00:03:08.980]They expand at the cost of natural landscapes
[00:03:10.900]that are deemed unused.
[00:03:13.050]We influence fire of course,
[00:03:14.360]and this would be a recurring theme
[00:03:18.260]that will come across.
[00:03:19.540]They are a number of processes
[00:03:21.760]that we're doing while we expand and grow and develop.
[00:03:26.540]Our climate is of course changing.
[00:03:28.250]And it's not just that it's changing,
[00:03:30.100]it's changed a number of times before
[00:03:31.440]in the geological timeline
[00:03:32.570]but it's changing faster than it has before.
[00:03:35.000]We are are able to track wild weather
[00:03:37.586]a little bit better now
[00:03:38.500]because of our advancements in technological society.
[00:03:42.440]So there's a lot going on.
[00:03:43.770]We find ourselves in this fast-paced world,
[00:03:45.750]time flies and we often struggle
[00:03:47.820]to just take a moment to breathe in.
[00:03:49.610]But this pandemic really connected us.
[00:03:52.690]Well, it certainly connected me back
[00:03:54.190]to my feet on the ground,
[00:03:55.950]the society take it in what I've got.
[00:03:58.890]And think of it, there aren't many things that connect us
[00:04:01.840]or connect the globe.
[00:04:03.840]Too often together we all often live in our own world
[00:04:06.390]and that's okay, that's what it is.
[00:04:08.790]But these are those moments where you
[00:04:11.870]just gotta take it in for the second
[00:04:13.200]and see what is going on around me.
[00:04:16.020]So what my talk will really focus on is open biomes
[00:04:19.970]and rangelands, of course.
[00:04:21.680]One of them grasslands,
[00:04:23.030]they're called a number of things depending
[00:04:25.710]on where you are in the world.
[00:04:27.070]South America, they're called pampas.
[00:04:30.440]In Asia you maybe find a lot of steppes,
[00:04:33.550]there also rangelands.
[00:04:34.650]And in Africa bunch of savannas as well as there
[00:04:38.040]which can be considered open biomes.
[00:04:40.990]But really what I wanna focus on are grasslands
[00:04:44.030]and what I have displayed out here are two simple boxes,
[00:04:47.730]taken from a Pausas and Bond's paper in 2020,
[00:04:50.570]looking at the dynamics of open biome versus closed biome
[00:04:53.330]and how they can switch between the two.
[00:04:56.280]And really what it boils down to for a open biome
[00:04:58.590]to switch to a closed biome.
[00:05:00.250]We go from open biome exceptional wet years,
[00:05:04.030]accompanied by long fire intervals
[00:05:05.420]which can become a closed biome and vice versa.
[00:05:08.050]A closed biome accompanied by exceptional dry years,
[00:05:11.410]followed by one to two fires can become a open biome.
[00:05:14.960]And the reason why this is important is because
[00:05:18.010]of a simple Whitaker model that was developed in 1975.
[00:05:21.380]Where he pretty much mapped out
[00:05:22.950]the entire world on two axes,
[00:05:27.070]temperature and precipitation.
[00:05:29.180]And rangelands or open biomes will find themselves
[00:05:32.670]in an envelope that's shared with a number
[00:05:34.270]of other ecosystems but each of them are unique.
[00:05:36.540]Each of them are unique systems.
[00:05:38.220]So this area that I kind of highlighted in red,
[00:05:41.540]ranges between minus five degrees celsius
[00:05:46.407]and about 25, 30 degrees celsius,
[00:05:49.150]and anywhere between 500 mils to 1500 mils of rainfall,
[00:05:52.380]which can sustain a number of ecosystems.
[00:05:55.140]Now, that might be pretty cool, you know more better.
[00:05:59.190]But the truth is that's not necessarily super cool
[00:06:01.990]when you think of a grassland system
[00:06:04.260]that becomes something else.
[00:06:05.950]You generally lose that grassland system
[00:06:08.130]and you lose the services that comes along with it.
[00:06:11.650]So as Tony mentioned, we know that fire matters
[00:06:13.957]in the rangelands and we know that woodland expansion
[00:06:18.200]is a bit of a problem right now.
[00:06:19.570]And it's a problem in the Great Plains,
[00:06:23.090]it's a problem in the South and South America.
[00:06:26.590]It's a problem in Asia, it's a problem in Africa.
[00:06:29.300]It's a problem in Australia.
[00:06:30.810]Everywhere we have these temperate zones
[00:06:33.120]and sometimes the subtropical zones,
[00:06:35.600]woodland expansion is a problem.
[00:06:37.157]We did a simple little study here to show
[00:06:39.240]how can we mitigate that?
[00:06:40.400]And what we found was when we looked
[00:06:42.160]at expansion over height classes,
[00:06:45.370]we realized that the only time when we actually saw
[00:06:47.920]an effect of expansion was when fire was combined
[00:06:51.940]with a herbicide application.
[00:06:53.880]And this was a little small study area down
[00:06:56.590]in Stillwater, Oklahoma.
[00:06:58.150]But most of the problem was that when you got to tall tees
[00:07:01.600]your herbicide didn't really do anything,
[00:07:03.680]and you really needed fire
[00:07:04.960]and you kinda needed higher intensity fire.
[00:07:07.370]And I know that Tony and Dirac knows a little bit more
[00:07:09.700]about that than I do.
[00:07:11.760]But as we scale this up,
[00:07:13.010]this idea of how can we manage our tree cover
[00:07:15.900]over the Southern Great Plains
[00:07:17.240]or any encroached rangeland,
[00:07:19.940]our current efforts are falling a little short.
[00:07:22.080]I've split three panels out of Kansas, Oklahoma and Texas,
[00:07:26.220]ranging from the year 2000 to 2018
[00:07:27.880]where we looked at tree cover on the y-axis.
[00:07:30.700]And this general trend where Kansas
[00:07:33.060]has as an increasing trend,
[00:07:34.940]whereas Oklahoma and Texas kind of starts where they are
[00:07:38.787]and they don't really go too much higher
[00:07:40.330]but the generally don't decrease.
[00:07:42.610]And we proved this actually looking at
[00:07:45.170]even though we had 10 years of brush management data
[00:07:48.550]during our time period of information
[00:07:53.040]on functional group cover.
[00:07:55.850]You'll notice the pink bars are just looking
[00:07:57.560]at the change between the year 2000 and 2017
[00:08:01.370]of each functional group.
[00:08:02.480]And the pink bars represent tree cover
[00:08:04.430]and all of them are positive.
[00:08:06.100]And that really means that all the time
[00:08:08.140]and money and effort that's been spent right now
[00:08:10.390]in the Southern Great Plains on brush management,
[00:08:12.470]it's not really working.
[00:08:14.250]So what's going on.
[00:08:16.360]We find that, well A,
[00:08:18.840]we need to really get better at mapping fires for example.
[00:08:22.550]We did a simple study looking at this in conjunction
[00:08:25.580]with the Kansas Department of Health and Environment.
[00:08:29.170]Where these guys have, I think in recent years,
[00:08:32.833]over the last 10 or 15 years, don't quote me on that,
[00:08:35.780]but they've been really concerned about smoke.
[00:08:38.400]And as fire generally occurs in the Flint Hills
[00:08:41.980]mostly in the spring and most there's a certainly
[00:08:45.900]a culture of burning.
[00:08:47.810]So smoke has become a huge concern.
[00:08:50.100]But in order to manage smoke,
[00:08:51.800]we actually need to know how much fire
[00:08:52.980]you have in the landscape.
[00:08:54.190]And what you're seeing on the left panel
[00:08:55.900]is a simple remotely-sensed map taken
[00:08:58.250]from a MODIS fire sensor.
[00:09:00.310]And on the right is a Kansas customized map
[00:09:03.440]on that same center.
[00:09:04.840]And what the customized map does is,
[00:09:06.750]well, if a fire was predicted by the MODIS algorithm,
[00:09:10.240]Kansas folks will send someone out
[00:09:11.760]to actually go and check exactly where the fire was
[00:09:13.730]and map that barometer.
[00:09:15.324]But what we find is that when they did that
[00:09:16.960]they actually improved almost 30%
[00:09:18.720]of the parameters detected, that's big.
[00:09:22.510]And what we took away from this message was,
[00:09:25.300]while we're really terrible at mapping fires in open biomes,
[00:09:28.177]there's a number of reasons for that.
[00:09:30.230]And the most obvious one is that open biomes
[00:09:32.470]such as rangelands recover quickly.
[00:09:34.420]And it might not be detected
[00:09:36.300]by simple reflectance techniques.
[00:09:38.430]And most of these remotely-sensed sensors
[00:09:40.640]that are out there today in fact,
[00:09:42.440]were developed to map forests.
[00:09:45.180]And what we also find out, well, we didn't it like this
[00:09:47.850]but there is really no substitute for ground-truthing
[00:09:49.780]or there's no substitute for field work.
[00:09:51.630]You gotta go out there and see what's going on.
[00:09:54.920]So we took this one step further
[00:09:57.310]and using some of Dan Uden's work from spatial imaging
[00:10:00.830]and we wanted to know,
[00:10:02.740]well, we've got the most frequently burnt tall grass prairie
[00:10:06.840]in the world.
[00:10:07.673]There is none other like the Flint Hills, it burns.
[00:10:10.690]And we wanted to know, well, just how much fire
[00:10:14.630]is required to sort of maintain this undesired transition
[00:10:18.690]which is woodland expansion.
[00:10:20.540]How do we keep it at bay?
[00:10:22.490]And what we did was...
[00:10:24.065]So on the right you're seeing a little animation
[00:10:26.010]that's just ticking through from the year,
[00:10:27.930]I think it's 2000 to 2017 or 2018.
[00:10:31.520]And everywhere you see these orange and red areas pop up
[00:10:36.660]it just shows the severity of the undesired transition
[00:10:39.330]which is the grassland becoming a woodland.
[00:10:42.760]And what we've actually quantified is that
[00:10:45.460]if we experience a fire between every...
[00:10:47.970]Any pixel that experiences a fire
[00:10:49.970]between two to three years,
[00:10:51.300]we can actually move away from that time decision.
[00:10:54.700]We can curb it, we can stop it.
[00:10:56.540]So if it is in the middle, for example,
[00:10:58.780]you kind of see it stayed green.
[00:11:00.690]And those are those acres that tend burn every year.
[00:11:03.370]There is no opportunity for woodies to come in.
[00:11:06.060]But on the edges, on the South is generally wetter
[00:11:08.370]and the East is the generally wetter.
[00:11:09.440]And of course the riparian zones,
[00:11:11.450]there's opportunities for woody plants to go in
[00:11:13.770]and its opportunities where fire generally
[00:11:15.860]doesn't carry as often because
[00:11:17.240]of the underground herbaceous layer.
[00:11:19.250]So it's really cool that now we have this information
[00:11:22.250]coming from the rangeland analysis platform
[00:11:24.510]to actually quantify exactly what's the
[00:11:26.300]desired fire return interval.
[00:11:30.130]And that brings me to my next slide
[00:11:32.440]that really talks about fire return interval.
[00:11:34.830]and it's perhaps, I guess.
[00:11:38.780]Maybe Tony would know better but fire return interval
[00:11:40.710]tends to be the most commonly talked about component
[00:11:43.750]of the fire regime.
[00:11:45.420]And early in 2020 Dirac and a bunch of us as well.
[00:11:50.010]We worked on this idea where,
[00:11:53.400]the fire regime actually is made up of
[00:11:55.760]a number of components and the return interval
[00:11:57.984]is just the one.
[00:11:59.030]And what we have on the left pie charts
[00:12:01.910]ranging from colors of orange to red
[00:12:04.290]are what we consider sort of eras of society operating
[00:12:10.340]on the world and on the landscape using fire.
[00:12:13.730]We kind of this is all theoretical
[00:12:15.880]and we call this the orange fire for example,
[00:12:19.810]the coexistence era where we have natives
[00:12:23.160]all over the world generally utilizing landscapes however,
[00:12:27.750]in terms of fire burning throughout the year, for example.
[00:12:30.720]So that would be the seasonality pie.
[00:12:32.750]So you could think of the seasonality pie broken up
[00:12:34.920]into 12 months and you could highlight exactly
[00:12:37.050]how many months do we detect fire.
[00:12:38.887]And we suspect that during the coexistence era
[00:12:42.220]people would burn as needed and that didn't change.
[00:12:45.062]It didn't really matter what time of the year,
[00:12:47.300]it was just perhaps more based on the conditions.
[00:12:49.930]We'll never know for sure but that's what we suspect.
[00:12:52.780]But if we take their seasonality pie
[00:12:54.430]and move it through each year,
[00:12:55.900]we can actually see how it's changed
[00:12:57.600]based on how society has behaved.
[00:13:00.510]So suppression era, we pretty much eliminated fire
[00:13:03.520]off that landscape.
[00:13:04.810]The shadow which we currently see green,
[00:13:07.490]we've reduced seasonality.
[00:13:09.050]So for example, as I mentioned,
[00:13:10.630]most fires in the Flint Hills occurred in the spring,
[00:13:13.350]sort of March, April.
[00:13:15.010]And now we're kind of approaching this wildfire
[00:13:17.580]that Tony mentioned that perhaps we are now getting back
[00:13:21.100]to the coexistence era in some of these components
[00:13:24.980]where we can find wildfires any time throughout the year
[00:13:28.890]and et cetera, for example.
[00:13:31.100]So what we now wanted to see was,
[00:13:33.810]well, how could we really studied
[00:13:35.230]this components of fire in rangelands?
[00:13:38.190]And the truth is it looks a lot like the shadow era,
[00:13:40.690]'cause we haven't really studied fire in rangelands.
[00:13:43.010]Because they are just many other concerns
[00:13:45.450]that we have to deal with.
[00:13:46.700]Tony brought this up.
[00:13:47.650]Safety, for example.
[00:13:49.690]So why this all matters is because
[00:13:53.390]we know fire as a global herbivore.
[00:13:56.200]And William Bond and John Keely did this cool study
[00:13:58.820]back in 2005 where they plotted tree biomass on the y-axis,
[00:14:02.700]plant moisture on the x-axis and the solid line
[00:14:05.610]sort of increasing linearly with plant moisture
[00:14:08.170]that pretty much showed the more water you have,
[00:14:11.410]the more rainfall you have the higher the kind of potential
[00:14:14.330]you can have for tree biomass or woody cover,
[00:14:16.820]or you can change it to something whichever you feel like.
[00:14:20.140]Number of plants, et cetera.
[00:14:21.430]It doesn't really matter at this point.
[00:14:23.230]But what they realized was we actually don't see that
[00:14:27.460]when we go out in the field.
[00:14:28.450]Most times we don't see that.
[00:14:29.940]What you actually get is something much less
[00:14:32.000]than the climate potential just because of our landscapes.
[00:14:35.560]We think of biomes, biomes are some sort of association
[00:14:38.900]of climate vegetation and fire.
[00:14:41.020]Fire is an integral component in developing these biomes.
[00:14:45.760]So consumer control really matters,
[00:14:47.930]and we can include fire in that
[00:14:49.490]but we can also include humans in there.
[00:14:51.620]We can include anything that influences the landscape
[00:14:55.700]to manipulate fire regime, that's what the consumer is.
[00:15:00.890]Some recent work has actually shown
[00:15:02.460]that over the last I don't know what is that 12 years or so,
[00:15:06.220]we've generally just seen a decline of fire activity
[00:15:09.330]at a global scale.
[00:15:10.950]And this is really in contrast to what we see
[00:15:14.640]when we're focusing to little areas such as what Tony
[00:15:17.030]was mentioning in the Great Plains
[00:15:18.280]where we start seeing these spikes in wildfires, et cetera.
[00:15:21.260]But from a global perspective,
[00:15:23.460]it's just generally decreasing that's...
[00:15:26.900]And data it's all that actually pointed that out,
[00:15:30.170]directly linked to agricultural expansion.
[00:15:32.710]And that might be in certain areas
[00:15:34.510]that once had huge fire components
[00:15:38.170]whether it be burned area or number of fires
[00:15:40.940]and no longer contributing that amount
[00:15:43.440]to the global signals.
[00:15:46.690]But also some previous work has shown
[00:15:49.810]that we know that fire is so important
[00:15:52.150]that it's actually the determining factor
[00:15:54.380]for these open biomes.
[00:15:55.550]And that's very clear in African savannas,
[00:15:57.820]for example if we think of passability
[00:16:00.070]between alternate states.
[00:16:01.890]And there's no substitute for fighting these landscapes.
[00:16:07.260]If we think of some places like tropical
[00:16:09.610]and subtropical Africa and Australia for that matter,
[00:16:12.160]fire is the reason why we have those landscapes,
[00:16:15.520]those savannas.
[00:16:16.540]Without fire, we really don't know what we're gonna get.
[00:16:20.170]And this brings me to some of my next ideas
[00:16:24.040]of conceptualizing this I suppose grand idea.
[00:16:29.150]But it's to think about how we've studied biomes
[00:16:32.170]over the past century?
[00:16:33.420]So we can sort of agree that the biome
[00:16:37.240]is the largest unit in our vegetation classification.
[00:16:40.770]But the truth is it's not just vegetation,
[00:16:42.540]it's climate and we know for a fact that it's also fire.
[00:16:47.460]If we think back to Clemens days,
[00:16:50.020]we know that climate was the idea,
[00:16:52.860]the sort of the one exogenous
[00:16:55.210]sort of factor driving vegetation.
[00:16:57.010]What we saw on the landscape was because of climate.
[00:17:00.320]And for several years, several decades,
[00:17:03.090]that was how this holy grail and that's just the way it is.
[00:17:07.040]And strangely enough, nobody will ever disagree with that.
[00:17:10.400]That climate really will determine vegetation
[00:17:13.010]but we now know that as we start diving into deeper details,
[00:17:16.680]there's other things that really matter.
[00:17:17.960]So we move from this climatic climate concept,
[00:17:20.900]all the way to the ecosystem landscape concept
[00:17:23.120]to national fire regimes.
[00:17:24.180]Where we see soil and water and elevation start
[00:17:26.810]to really influence the vegetation patterns we see.
[00:17:29.750]But as we move to this fire idea,
[00:17:32.140]we realize, well, actually if we have vegetation
[00:17:35.900]as a result of rainfall or climate,
[00:17:38.640]we can actually burn that
[00:17:40.130]and it can look like something else.
[00:17:42.870]But in today's time,
[00:17:44.310]we realize that who's really controlling fire.
[00:17:47.460]Why do we see declines of fire over the world,
[00:17:50.240]what's happening?
[00:17:51.340]We think that, well, we know that most of the fire today
[00:17:55.563]is ignited by humans by some way or another.
[00:17:58.940]Yes, there are exceptions.
[00:18:01.100]Lightning fires certainly happen,
[00:18:03.240]but the incidences of those are not as high
[00:18:05.260]as the ones that are ignited by humans.
[00:18:08.564]I don't remember exactly what caused the fires in Australia,
[00:18:13.483]but I know that most of the indigenous groups down there
[00:18:16.800]were not very happy with the kind of practices
[00:18:19.700]of prescribed fire.
[00:18:21.000]There was a huge suppression treaty happening
[00:18:24.240]over recent years and then accompanied
[00:18:28.010]by a number of years of drought
[00:18:29.380]which actually led to the Australia fires.
[00:18:33.040]But if we dive deep into this idea
[00:18:34.950]of biomes changing over time,
[00:18:39.500]we can jump into areas that used to burn a lot.
[00:18:42.970]So we know if we look at temperate grassland savannas
[00:18:45.980]and shrub lands all over the world,
[00:18:47.760]we know these areas used to burn a lot.
[00:18:50.050]That's what maintained,
[00:18:52.980]open biomes stayed that way because of fire,
[00:18:56.750]thinking of the people that live there.
[00:18:58.810]So when we compare that now.
[00:19:00.440]If we consider the amount of contribution
[00:19:02.830]of each continent on earth,
[00:19:05.570]contributing to temperate glass and fire signal,
[00:19:07.900]it's pretty low, it's very low.
[00:19:09.780]In fact, there's like a tiny slither
[00:19:11.650]of red showing out there and that might be the Flint Hills
[00:19:13.960]but it's not that high.
[00:19:16.240]If we switch over to the tropical and subtropical grasslands
[00:19:19.180]what we actually see is only Africa and Australia
[00:19:21.290]is really contributing to an annual fire signal
[00:19:24.780]for this entire biome.
[00:19:26.010]You could even think of it as it's getting the biome signal.
[00:19:29.320]So this again, there's this mismatch between
[00:19:32.130]what we know set these biomes up in the way they are,
[00:19:36.540]but now people are controlling it.
[00:19:38.890]We don't really know what that means for the future.
[00:19:41.560]So if we can focus a little bit further
[00:19:43.430]into this temperate grasslands for example,
[00:19:45.880]we wanted to dive a little deeper and see what's going on.
[00:19:48.050]Why do we see these varying signals?
[00:19:50.140]So one little thing that has popped up for us
[00:19:53.240]is that we notice a difference in fire season
[00:19:56.490]throughout the temperate biome.
[00:19:58.290]So in North America as we know,
[00:20:00.210]most burns happen in the spring.
[00:20:01.980]But when we switch over to Asia,
[00:20:03.450]most burns are happening later in the year.
[00:20:05.510]There's no right or wrong
[00:20:07.090]but that influences the fire regime,
[00:20:10.090]that actually influences the fire intensity for that matter
[00:20:13.020]when you decide to burn.
[00:20:14.310]And fire intensity is a large component or the fire regime
[00:20:17.407]and we don't know what that means for changing
[00:20:21.050]at least at the biome scale.
[00:20:23.890]And when we take the step further,
[00:20:25.630]we developed some theoretical ideas.
[00:20:28.200]We like to do that if you haven't noticed by now
[00:20:30.720]but what we have is each biome listed from top to bottom.
[00:20:35.230]There's no real order.
[00:20:36.450]I think it's in fact alphabetical.
[00:20:38.570]And we have the mean burned area over a 17 year period.
[00:20:43.460]The gray, the darker gray bars are actual MODIS fire
[00:20:46.043]that we calculated for the percent mean burn area
[00:20:48.620]for a particular biome.
[00:20:50.100]And the gray bars are what we think
[00:20:52.930]is a sort of a pre-settlement signal.
[00:20:55.650]We don't really have data for this.
[00:20:57.050]We would probably never really get data
[00:20:59.600]but they are global scale papers written
[00:21:02.480]by David Bowman et centra, Stephen Pyne
[00:21:04.890]who talk about these patterns.
[00:21:07.150]So for example, we could see something
[00:21:09.410]like the temperate grasslands had a generally
[00:21:12.410]a fire signal similar to the tropical grasslands.
[00:21:15.730]But where do we see the biggest changes nowadays,
[00:21:19.090]it's out there.
[00:21:19.923]So we know that temperate grasslands do not burn as much
[00:21:22.880]as they used to.
[00:21:23.980]But all of a sudden we seen tropical forests burn
[00:21:26.820]a lot more than they used to.
[00:21:28.680]We don't really know what that means for the longterm.
[00:21:31.530]And we actually wanted to find out exactly
[00:21:33.570]why temperate grasslands are doing what they're doing.
[00:21:36.500]And we looked at this from a land cover perspective.
[00:21:38.980]So the top spatial map is just showing you the amount of...
[00:21:45.730]We looked at grassland fire activity over time.
[00:21:49.570]So what we got from each pixel was a slope.
[00:21:53.160]So we know, well, unfortunately what we see
[00:21:56.160]is decreasing slope for every pixel in this biome
[00:22:00.900]and each pixel refers to a particular land cover type.
[00:22:05.630]And the one that shows the biggest decrease over time
[00:22:09.210]is the grassland pixel.
[00:22:10.600]And almost all of the other pixels align somewhere negative
[00:22:14.440]which generally just shows a decrease
[00:22:15.880]in fire activity over time.
[00:22:17.650]But the most pixel that's representative in this biome
[00:22:20.820]is in fact grassland pixel.
[00:22:21.990]So it's carrying the signal essentially
[00:22:24.370]of showing a general decrease over time.
[00:22:27.460]That's a concern 'cause we don't know
[00:22:29.520]what that means for our systems.
[00:22:31.170]We don't know what that means at a biome scale.
[00:22:34.250]So and I'm approaching the end of my talk,
[00:22:37.290]but I wanted to just bring this slide back up
[00:22:39.680]about why it's important to think about our open systems
[00:22:44.280]in a more holistic view that they are able
[00:22:48.870]to become something else.
[00:22:50.550]And it's really essential that we keep processes
[00:22:52.740]that are in the yellow box,
[00:22:54.810]keep them the way they are if we want to maintain them.
[00:22:57.770]And we are building a case
[00:22:59.630]about why we should maintain them the way they are.
[00:23:01.800]So we've isolated most of the grasslands in the world.
[00:23:04.990]We actually refining this but these are,
[00:23:07.570]if you just focus on the temperate regions
[00:23:09.950]which are on the top section and mostly on the bottom.
[00:23:13.410]We wanted to see how many of these eco regions
[00:23:16.490]in parts of the world meet this criteria.
[00:23:19.010]And all we did was we took little grassland pixels
[00:23:21.890]and we wanted to just quantify how many of them meet
[00:23:24.380]this queens case criteria?
[00:23:26.550]How many of these pixels are surrounded
[00:23:28.250]by eight other grassland pixels essentially?
[00:23:31.050]And we find some really cool results.
[00:23:34.300]Well, cool for North America,
[00:23:36.100]because they are two in that region.
[00:23:39.110]The Wyoming Basins Steppe and Nebraska Sandhills
[00:23:42.020]in fact have a very intact grassland system.
[00:23:45.930]But they are many others that don't.
[00:23:48.950]We think that when we wanna consider
[00:23:51.630]what it means to be intact,
[00:23:53.120]we know that it's more than just how many pixels
[00:23:55.380]are next to one another and that's for sure.
[00:23:57.680]But if we can identify regions such as these,
[00:24:00.920]we might be able to prioritize where we wanna go.
[00:24:03.920]So I know I'm preaching to the choir here on this talk
[00:24:07.610]but I think it's really important why we need
[00:24:10.130]to be predicting these major last grasslands.
[00:24:12.980]And other than these open systems
[00:24:15.950]there are several world heritage sites out there.
[00:24:17.940]They are home to many endangered species.
[00:24:20.730]And the cultural hidden teach that actually exists
[00:24:23.150]on these landscapes are, it's invaluable.
[00:24:26.530]We really can't replace that.
[00:24:28.660]And what's very cool about them is that
[00:24:30.990]no matter where they are in the world,
[00:24:32.710]they are all linked by this lifestyle dependent livelihood.
[00:24:35.560]And that's something really cool that we don't wanna lose.
[00:24:38.740]However, we cannot talk about why
[00:24:41.790]they are these last grasslands
[00:24:43.020]without thinking about the threats.
[00:24:44.580]And in 2017, we published a paper looking at
[00:24:48.070]number of land use changes using crop scape data
[00:24:50.410]which is high-res, I think it's 3 meter resolution data.
[00:24:54.000]Just we wanted to know how many
[00:24:55.210]of those grassland pixels became something else
[00:24:57.150]over a 10 year period.
[00:24:58.780]Initially, we thought it was a small period of time.
[00:25:00.900]But when we looked at the results,
[00:25:02.030]we realized there were enough of them
[00:25:03.710]that turned about eight times over the time period.
[00:25:07.130]So between Oklahoma and North Dakota,
[00:25:09.140]we found that places like the Sandhills and the Flint Hills
[00:25:12.090]actually remained relatively stable.
[00:25:14.000]And some of our latest papers are actually
[00:25:16.740]confirming some of that result.
[00:25:18.600]But we do realize that where they did change,
[00:25:21.400]most of the grasslands became either croplands
[00:25:24.000]or became encroached by woodlands.
[00:25:27.180]And the one other threat I wanna add to that
[00:25:30.160]is energy development.
[00:25:31.460]And perhaps in North America,
[00:25:33.460]most of the energy development is,
[00:25:36.140]well, at least from a development perspective
[00:25:38.040]it could be mostly wind.
[00:25:39.950]But if you move to Asia,
[00:25:42.230]most of the threats in the Asian grasslands are mining,
[00:25:45.500]and it's oil mining and mineral mining.
[00:25:48.840]So the giant elephant in the room,
[00:25:52.090]we control most of the world's fire.
[00:25:53.890]It's really up to us to maintain these biomes.
[00:25:56.400]And especially if we don't wanna lose
[00:25:59.300]our temperate grasslands.
[00:26:01.180]So some concluding remarks is that
[00:26:04.120]the world is changing of course,
[00:26:05.850]but it's really changing at a faster rate than we think.
[00:26:08.420]And I have to remind myself every day
[00:26:11.140]that the small-scale changes that we make
[00:26:12.750]can really make a big global ecological impact.
[00:26:17.060]And something that really stood out for me
[00:26:19.360]when I was looking into these regions of the world,
[00:26:22.980]these temperate grasslands
[00:26:24.030]when I compared North America to Australia,
[00:26:27.140]both regions have a shared vision.
[00:26:29.160]But in Asia, a shared region meant protected area
[00:26:32.530]that was federally mandated.
[00:26:34.140]In North America didn't necessarily mean a protected area.
[00:26:37.110]In fact, most of the landscape is privately owned
[00:26:39.110]and I know you know that.
[00:26:40.770]The point is it doesn't matter.
[00:26:42.080]It doesn't have to be protected area.
[00:26:44.140]As long as there is a shared vision, that's all.
[00:26:46.900]As long as it's shared vision,
[00:26:49.030]we all have the same common goal.
[00:26:52.580]We don't really know what reorganization
[00:26:54.520]of biomes will look like.
[00:26:56.130]We don't know what it would lead to,
[00:26:58.020]and we might have to rethink what we think we know.
[00:27:02.256]And that might be something for the future
[00:27:04.560]or for future generations or it might creep up on us
[00:27:08.280]a lot faster than we are prepared for I suppose.
[00:27:11.590]And another thing that it's really important
[00:27:14.050]as we've come into this age of information
[00:27:16.180]where a platform such as the Rangeland Analysis Platform
[00:27:19.600]are becoming really available and easy to use
[00:27:21.840]for real-time monitoring.
[00:27:23.620]And they've used remotely-sensed information combined
[00:27:26.970]with some epic long-term ground-truthed data points
[00:27:31.140]to develop those products.
[00:27:34.320]I really think that that combination
[00:27:35.900]between field data and the remotely-sensed products
[00:27:39.300]is really where we headed for some global scale
[00:27:41.944]so it's where are we gonna keep our toes on it.
[00:27:44.610]And with that, I say thank you very much.
[00:27:50.820]Thanks Rheinhardt.
[00:27:51.653]We actually have a question lined up right now
[00:27:54.892]from Andrew Hopkins.
[00:27:56.450]I'll unmute you Andrew and let you ask it.
[00:28:01.810]Just curious how much of the woody encroachment,
[00:28:07.370]what's that doing to aquifers
[00:28:11.280]and water supplies and so forth?
[00:28:14.740]Is it having a pretty negative effect?
[00:28:17.370]A very interesting question.
[00:28:20.310]So I don't know exactly what the woody encroachment
[00:28:24.150]is doing at least from a global perspective.
[00:28:26.190]But I know that during my time in Oklahoma state,
[00:28:29.610]there were a number of eco hydrological sort of problems
[00:28:37.110]that they found when as Juniper increase
[00:28:39.810]the amount of water that was available
[00:28:42.950]to the herbaceous layer most certainly dropped drastically,
[00:28:45.700]even more so than just being out completely.
[00:28:48.400]But I know for a fact, so the Sandhills
[00:28:50.830]and I think it sits under the Ogallala aquifer sits there
[00:28:57.180]and it touches about eight States.
[00:28:58.810]We don't really know what that means
[00:29:00.170]if we start expanding more woods start to come in.
[00:29:04.010]We don't know what that means in terms
[00:29:05.800]of how much water they will actually take,
[00:29:07.550]which would really affect that ecosystem service.
[00:29:10.990]So quantifiably, we don't know what that means
[00:29:13.000]at bigger scales but we know that generally woody plants
[00:29:17.270]tend to out-compete herbaceous layers for water.
[00:29:24.620]All right Rheinhardt,
[00:29:25.510]so what do you think as far as the doom and gloom
[00:29:32.130]versus bright side of this?
[00:29:33.370]How can you speculate a little bit
[00:29:36.270]and see what we would have to do
[00:29:38.830]or what the future is looking like here
[00:29:40.960]for grasslands and steppes.
[00:29:43.570]Good question, Caleb.
[00:29:46.110]Well, I thought of it before and I thought of it as,
[00:29:52.320]I think it might be a two-step process.
[00:29:54.450]One, we need to increase awareness of our grasslands
[00:29:59.300]that are in peril.
[00:30:00.760]We know publications but publications can only get us so far
[00:30:04.707]and most times it only reaches the scientific community.
[00:30:08.130]What we really need is we need to have politicians involved.
[00:30:12.820]And I think of the Paris Agreement,
[00:30:14.290]I don't know at what point did climate emissions
[00:30:17.000]or did carbon emissions become a talking point
[00:30:19.611]for the politicians?
[00:30:21.200]I don't really know exactly
[00:30:22.470]but there has to be that sort of breakthrough
[00:30:26.360]where we need a list of what is happening to our world
[00:30:29.830]and we are changing it,
[00:30:31.190]and what does that mean for the longterm?
[00:30:33.330]So I tend to equate it to a Paris Agreement type thing
[00:30:37.570]from a globe perspective.
[00:30:38.730]But at a smaller scale, if it's from the NRCS
[00:30:42.370]that are sort of focused on the Great Plains
[00:30:44.573]that are looking at ways to increase funding,
[00:30:48.090]to increase research, more stakeholder engagement.
[00:30:52.290]And that's sort of way we got ahead on
[00:30:54.990]perhaps the small scale stuff
[00:30:56.470]which would eventually tend to move
[00:30:58.810]towards the global scale ideas.
[00:31:01.640]And if I think of something like Asia
[00:31:04.310]where Mongolia sort of mandated,
[00:31:06.770]they wanted each about 50 or 35%
[00:31:09.429]of the entire country protected by 2030.
[00:31:14.254]That's really cool to have that sort of mandated
[00:31:18.960]but they've got all the,
[00:31:20.520]they're controlling all that land
[00:31:22.160]and that's just the way they're doing it
[00:31:24.420]and that's fine.
[00:31:25.600]So I think there might be a number of ways
[00:31:28.280]of which we can get to it but I just hope we do get to it.
[00:31:31.690]Thanks everybody for coming.

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People, Fire and Global Biome Divergence in the 21st Century

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