Video
A Thousand Years of Landscape Change in the Bandelier Wilderness
Transcript
Karen:Good afternoon everyone. Welcome to ArcheoThursday. My name is Karen Mudar and I'm an archeologist in the NPS Washington Archeology Program, which is hosting this series. This Fall and Winter, we're exploring the Anthropocene and Climate Change in Archeology.
Today, Craig Allen is going to continue to examine some of these climate change and fire related issues. He's going to talk to us about a research program that he's been carrying out at and around Bandelier Wilderness. He's been elusive about the details of his talk. His title, “1,000 Years of Landscape Change in the Bandelier Wilderness” will have to suffice.
I can, however, tell you a bit more about his background and credentials. Craig Allen is a research ecologist with the US Geological Survey. He is station leader at the Jemez Mountain field station based at Bandelier National Monument. He's worked in the Jemez Mountains since 1986. He's one of the principal investigators of the USGS Western Mountain Initiative, an integration of research programs that study global change and mountain ecosystems of the western US.
As I mentioned last week, I attended a lecture that Craig gave a couple of years ago, in which he talked about the ways in which land use practices had contributed to soil erosion in Bandelier. His experiments to devise simple ways to stop erosion and stabilize the soil had much in it for archeologists. It was an excellent presentation and I anticipate that his talk today will be just as good. Thanks for being with us today, Craig. Thanks very much for your patience while I got organized.
Craig:No worries. Thank you for the invitation. Elusive, is that how you would define it? By the way, if people have questions along the way, feel free to unmute your phone, I guess, and ask. I have a fair number of slides and I'll move through them otherwise, quickly enough. Sometimes it's better to stop when it's up on the screen and the thought is fresh. I don't mind that.
We'll talk about landscape change in this particular landscape of Bandelier. Oops, that's not what I want. What I want is ... You may have to bear with me about navigating this thing first until I get it working. The title slide, just adding ... It's a lot of people have contributed to ideas and some of the work that's presented here.
Just the map, the Jemez Mountains. Bandelier National Monument is an old Park Service unit from 1916 established to protect cultural resources. It's located in the southeast flank to the Jemez Mountains. That's where the red arrow is pointing to there. Sort of at the south end of the Rockies, the margins of the Colorado Plateau and Desert Basin Range.
Zooming in on the Jemez, you can see it's a big volcanic landmass with a central Caldera that's about 15 miles across, which is called the Valles Caldera. Bandelier's outlined in the yellow. By the way, it seems likely within hours to days, there will be a new Park Service unit. There's a 90,000 acre National Preserve called Valles Caldera National Preserve, which encompasses that ... Let's see if I can make this little pointer work.
This is the caldera. There's the unit. It touches Bandelier in the northwest corner. It looks like it's part of the defense appropriation bill, it looks like it will probably pass. There's been an effort to make a Park Service unit there since the late 1800s. Anyway, it's a little bit exciting here in this landscape.
The landscape involved here ranges from elevations up to 11,000 feet here along the rim of the caldera, down to just a little over 5,000 feet where this is the Rio Grande crossing across, from north to south. Bandelier has that whole elevational transect. We're going to focus on these lower elevation mesa tops, which are dominated by piñon and juniper trees, a woodland system. Let me get back to the clicker.
Zooming into a vegetation map of the park, the main part of Bandelier. It's these orange mesa tops that are this woodland vegetation. This is the primary settlement zone, and agricultural zone, for Ancestral Puebloan people, which are what the cultural resources at Bandelier primarily was established for.
This is what that area looks like from an airplane, over the Rio Grande, at the bottom of the field of view, looking back to the west over the mesas. I took this about 20 something years ago. We're going to focus, in particular, this is a block diagram showing that elevation gradient and vegetation gradient. We're going to focus on a one- hectare watershed for part of this, called the Frijolito Watershed, which is at the upper boundary of that woodland type, where it interfaces the bottom edge of the ponderosa pine forest type, which is a much taller pine.
This is zooming into that. Actually, I'll just back up and say just a small bit more. I've been working here continuously since the fall of '86. I actually did my Master's thesis research here earlier than that. Coming here will be the 34th year in a row that I've been doing field work here in the Jemez, in and around Bandelier. It's been really a great privilege to be able to be in a place so long. I'm one of the 100 or so ex-Park Service scientists that in 1993, the biological ecological scientists and the Park Service were transferred over to a short-lived agency called the National Biological Survey. By '95, we ended up in USGS as part of ... Which is why there are a large number of biologists and ecologists in the USGS. Then working here, based here at the park this whole time, co-located with land managers in this particular way of trying to support conducting research but doing it in a way to try to be supportive of land managers, not just Park Service land managers, but more broadly in the area.
In the '80s, I did both my Master’s and PhD studying various aspects of landscape change. Many of the studies I'm reporting on here really evolved organically, I guess, out of that work from the beginning. From the beginning, my perspective, my training was as a geographer early on, then as an ecologist. I've always viewed humans and nature, these have always been interactive where we're linked increasingly so, especially with the theme of your talks this fall and the Anthropocene. It's pretty clear human influence is ... Natural doesn't mean much without people on this planet anymore. As ecologists, it's been painful for ecologists to get to that point in the last 30 years, but they're pretty much there, I think.
Anyway, here is this watershed. The ridge line is here. That's the top of the watershed. This is 2 and a half acres, Frijolito Watershed, so called because there's 100 room archeological site, Classic Pueblo Period, from the 1400s to the mid-1500s, here just above it. In '93, we began quite a bit of work trying to understand run off and erosion processes here, which we'll talk about a little bit.
Erosion is a big issue at Bandelier, identified concurrently - well it's actually historically - was identified from the '30s on in various little documents you could see in the park. In the '70s, feral burros were considered to be the cause. The Park Service, after the first natural resource research done, was looked trying to understand what was causing the erosion and basically implicating the burros to justify in the end, shooting them.
In the '80s, when I started working here, it was clear there was an immense amount of erosion in these woodlands, these so-called PJ woodlands - piñon- juniper woodlands. At the same time there was a very large archeological survey effort going, underway, led by Bob Powers with many Park Service archeologists involved, that was a decade in length. They, similarly, were observing the impact of erosion on culture resources.
From that point forward, there was this linked thread from both the cultural and the natural resource perspective at Bandelier about we need to better understand what's going on with history of erosion, the magnitude of it.
You could see that huge areas were basically desertified. This shouldn't be a desert. These are places with 14 to 16 inches of precipitation annually on average, highly variable through time, but huge areas that looked like this in the heart of the wilderness. By the way, Bandelier is about 33,000 acres. The majority of it, 2/3 of it, or so, is congressionally designated wilderness. Essentially, all of this piñon juniper woodland landscape is in the designated wilderness.
The soils are old. They primarily formed during the last Ice Age during completely different vegetation types on these mesas. Again, this is a showcase archeology site [inaudible 00:16:13] down near the visitor's center in Frijoles Canyon. It's actually rather atypical of the archeological sites in Bandelier. Most of them are on the upland mesa top surfaces. The perennial stream in the background was the big attraction here.
Of course, you folks all know this, but it's important to recognize these people didn't go away. The descendants of the people who lived in Bandelier are, for sure, in direct linage with the folks from what we call San Ildefonso Pueblo and Cochiti Pueblo. Bandelier was on the straddles, the historic boundary between these 2 groups, who actually represent different language groups. The ethnographic history, their oral histories, and the archeological record are consistent. Basically, for those of you that have been here, the Frijoles Canyon was essentially the dividing line between the Keres speaking people to the south - Cochiti Pueblo. The Tewa folks to the north - San Ildefonso. This is modern Taos Pueblo.
Little bit of Bandelier actually has about 3,000 ... Actually it is literally right at 3,000 archeological sites that have been surveyed to date. Pretty much everything except some of the really steep terrain has been inventoried by this point. It has site densities that essentially equal those of any Park Service unit, including places like Chaco and Mesa Verde. This is the woodland zone, roughly, circled in green. This is an outline unit of the park, that's actually spatially in the correct location. You see the high density of sites. This is where people were living and working and farming for many centuries.
When the archeological survey was starting, the big survey, there in the '80s, after their first field season, we had a sit down meeting. They were asking if there was anything else that was worth collecting at the sites, in terms of site data. We shared notes about the magnitude of erosion, so they started to collect erosion data. The map you see on the left is from the last few years of the survey of the sites where they did collect erosion impact data. The red sites are the sites that were being affected by erosion of one sort or another. The green ones were the ones that were not. The main point here is that just the vast majority, well over 90% of the archeology sites, particularly down in the woodland, were being damaged in one way or another by erosion processes, primarily sheet erosion, significant levels of sheet erosion. There's some pedestal building stones there.
In the Frijolito Watershed we had all kinds of sediment traps. We literally just this year so ... For 20 years we were running this runoff and erosion work. In this field, in the photo here, you can see this is a 1 cubic meter. It's just a wooden half box sunk into the ground that captures the run off and the sediment. When we installed that for, I think for four years, we sieved the sediment coming out of this and similar sediment traps. Up here in the top are some of the over 1,000 artifacts that one rain storm event, this June 29, '95 event, put more than 1,000 artifacts into this sediment trap from 1 thunderstorm, draining a tenth of a hectare. This is a big part of what the archeological, or cultural resource issue with erosion was, is that it was literally smearing the archeological record across the landscape in a really profound way.
One question is, is we could see that this was how the landscape was behaving. We were measuring the rates of soil erosion at that point in time. Maybe they've always been like that. Was there something new? Was there something that Park Service management needed to be concerned with?
A couple different ways to approach that. I've done an immense amount of work with dendrochronologists, mostly folks from the Tree Ring Lab. In this case, this is Peter Brown, who has his own little tree ring lab out of Fort Collins, Colorado. In that watershed ... You can, of course, precisely date to the year. We dated every live and dead tree in that watershed. The junipers are not precisely datable. Those we actually had to estimate by size, age regression. The tree ring dating pattern, their cross dating doesn't work on that particular species, the dominant there. What we see here are the timelines of the logs, the dead logs that Peter Brown and I, we sampled basically every scrap of dead wood in that 2 and a half acre piece of hill slope. These are the timelines. This is calendar years here on the left, back to 1600.
The bark date is designated by a little vertical bar at the end of the line of the timeline for that tree. These would be the inner dates. These would be the last dates. 2 different species, the small pine, piñon pine, pinus edulis, the large pine ponderosa pine. This little grey shaded zone is the 1950s drought. You see this big mortality pulse. Most of that dead wood we were looking at that time, was from the 1950s drought event, which is the last severe drought before the current drought we've been in. We've been in droughts since the late '90s here in this region, driven presumably, it's thought at this point, these decadal scale droughts are driven by decadal scale sloshing of the Pacific Ocean.
There's a phenomenon called the Pacific decadal oscillation that basically drives the frequency of El Nino versus La Nina events. El Nino episodes, when the eastern Pacific is warm brings wet weather to us, well, wet winters. The jet stream comes farther south in el Nino conditions and the winter storm tracks cross over us. During la Nina conditions, the jet is farther north and the winter storm tracks miss us. We can have almost no precipitation in some winters.
The '50s - we can see with tree ring reconstructions going back for 2,000 years - that on the order of a 30 year oscillation, we oscillate in and out of these dry and wet periods. About twice a century these happen. The '50s was the last severe drought episode and at this locality, it killed essentially all the ponderosa pine on that site that had been alive. More on that in a minute.
Because we dated ... Those were just the dead wood on the landscape. We also cored all the live piñon trees. There were just literally just 3 live ponderosas available in and adjoining that watershed. We're able to actually show you in map form what this landscape looked like through time back to 1600 when the earliest trees started. I'm going to go through a series of these maps that look like this. The different symbols represent different tree species. ponderosa pine is green. piñon is the orange. juniper is the green triangles. When they die, they change to a different color. When they die, we have also mapped where the logs are on the landscape laying on the ground precisely. Those ponderosas, they'll be mapped as green and piñon is orange.
We don't know when the log hit the ground in the past. We're showing what the map position of it is today. The important point here is, you see in 1600, there are essentially no trees on this landscape. We believe, actually, in the big archeological site of Frijolito, which was occupied until the mid-1500s, a 100 room pueblo was sitting right here, just adjoining this. They left for reasons of their own. It wasn't related to Hispanic settlements of the area. They were already off these mesas at that point. They had abandoned this part of the world just before this. We actually believe that we have the demography, the demographic history of tree recolonization of this site after it had essentially been deforested. One of the leading hypotheses about why the Puebloan people left these mesa tops was that after 300 years of intensive occupation, they had deforested it.
Anyway, we have some evidence of that. These trees can live quite a bit longer than 400 years. Mesa Verde, you find, or you did until all the recent fires, 600 or even 800 year old piñons and the Utah juniper there is date-able. You can date back that look like they colonized after the Puebloans left circa 1280. We don't have anything anywhere near that old in our woodlands. We believe that part of that is because the occupation and the subsequent abandonment was several hundred years later in this landscape.
We're toggling through. This is now 1650. What you're seeing is ponderosa pine establishing at this point. We're in the Little Ice Age. These conditions were favorable for ponderosa pine, probably to push a little bit farther down slope then is comfortable for them today. You see down there's a little rocky area at the bottom and a little spot up here. These are rocky spots on the landscape that had piñon and juniper establishment. Those are the first places.
The heart of this watershed was actually ponderosa pine forest. Here's 1750. 1800. You see this pattern in the whole middle, mostly the whole upper part is ponderosa pine. Then 1850, probably the junipers ... Again we can't precisely date them. I think we're giving them a few too many years because I think they should have tracked with the piñon. Now watch what happens. At this point is when the surface fire patterns, you heard from Chris Roos last week, stopped. The piñon and the juniper are very sensitive to fire. During the surface fire period, they were growing in these rocky places that were not supporting the surface fire, but in the middle of that watershed, no.
By 1900, they're starting to show up all over. By 1940, you see that there are piñons and junipers established widely through the whole watershed. There are still some live ponderosa pine. By 1960, at the end of the 1950s drought though, every ponderosa pine in that watershed had died. They are present only as logs. This system that, for a couple of centuries was ponderosa pine dominated had become dominated subsequently by piñon and juniper, who are now the dominants by 1960s.
Jumping ahead another 40 years to 2001, which is picked for a particular reason, you see that the density of ... I'll just toggle back and forth between 1960 and 2001, just continued to go up. There was a wet period from the late '70s through '95. Subsequent to that we started to go into drought. 2002 was the worst year for tree growth in the last 1,000 years in the Southwest, definitively, by a region-wide tree growth assessment that's been done. In 2002 and 2003, all these piñon that used to be alive, basically every mature piñon died. Again, just to toggle back. That actually, if I mapped it in 2003 it would have looked the same in terms of that. They died literally within a 6 month window, a big transformation in the landscape.
Today, the landscape looks like this. Yet, we know that for a couple centuries much of that water should actually look something like this, an open stand of ponderosa pine with enough grass coverage to support surface fires, because there were fire scars in that record on many of the trees.
Again, people had a huge role in this history because it seems that the woody plants had to start from ground zero there in the late 1500s. What do we know about the density about human occupation of the landscape? To push this back a little farther. Regional scale patterns of population density in the Southwest. By the way, we're here. This is the Jemez. Bandelier sits right about there in this spot. In the north. This was just after the evacuation of the Four Corners by the farming peoples. Bandelier's there.
Zeroing into the, we'll now go to the archeological survey data for this part of the world, and all of this has been surveyed. Here is that one hectare watershed of Frijolito that we call the Frijolito watershed. We're going to look at the archeological evidence through time around that. Here is 2,000 years ago. A little bit of Archaic lithic scatter stuff.
Here is 1200. AD 1200, before the influx of immigrants from the Four Corners. Again, you see the different sizes of the symbols represent the size classes of the different types of features. By 1350, originally, the people who lived in these scattered, smaller room blocks structures, probably family, extended families. Then the aggregation occurred through the 1400s and into the 1500s. These red squares are communal pueblos of one to several hundred rooms. Here is Frijolito the pueblo that… which we named the watershed after.
You can see, though, that this landscape's had a lot of people in it for several hundred years. Estimates of how much of that landscape on the uplands they would have had to utilize for farming to support the populations that were estimated. What is now the Bandelier wilderness is estimated to have had between 1500 and 3500 people living in it, essentially continuously from the late 1200s through the mid-1500s. On the order of 300 years, there were 1 to several hundred thousand people living in the untrammeled pristine Bandelier wilderness.
I think we can skip that. That's just a little detail. Here's piñon. This is, if you look at the decade in which the trees established, you see there's this tidal wave of piñon establishment after the surface fires stopped in this time period. I forgot to show you the fire scars when I showed the timelines of the individual old woody trees.
The point of this is simply, this is from Henry Gracino Meyer’s dissertation work at El Malpais National Monument where they have a longer than 2,000 year tree ring chronology from four different species, actually. It's probably still the single best precipitation climate reconstruction in the region. When you see on all time scales is that drought is a natural feature of this landscape. The precipitation is variable on all time scales, essentially, is the only point I would make here.
You see the '50s drought. The '50s drought is shown here. The current drought, because Henry's work stopped right when the current drought kicked in. We are now in a drought that's similar in magnitude to what happened in 1950s. These are some of the trees that have died recently. Actually, these are remnant ponderosa pine from the '50s drought on the ground. These are piñon that died in '02, '03. These are, similarly, ponderosa pine that died in '03 as well up on that mesa top surface.
Basically the bottom margin of the ponderosa pine zone has been dying back through these drought episodes in the 20th century. This is from a paper that actually with a colleague we published in '98, in, actually, the Proceedings of the National Academy of Sciences because what was the big story? It was about a rapid ups slope shift of the boundary of the ponderosa pine zone. The bottom edge of the ponderosa pine zone retreated up slope by a mile and a half in less than 5 years during the '50s drought. Basically, the bottom fringe of the ponderosa pine died back.
During the current ongoing drought, ponderosa pine, the bottom portion of that distribution, has continued to retreat up slope. It's another whole topic. Most of my work in recent, in the last 15 years, really has been climate change related, supported by a USGS climate change set of projects. That's projected to continue. This was interesting because this remains till today the largest rapid shift of an ecotone, of a vegetation boundary that's been documented in the literature.
Here's 2002. Here's the drought- instrumental observations of drought- in the US. You can see centered on the Four Corners and Bandelier is there. This is what it did to those trees. I showed it to you in this obtuse ... Maybe I should have started it this way. I'm showing how the piñons died. This is how it looked likes when you're standing there in 2002, 2003. Here's fall 2002. This is part of Bandelier. All of the orange canopies you see are ... These trees are already dead. These are the piñons, the small pine trees.
The next slide is 18 months later after the needles have dropped. You see the grey skeletons of the piñon. The trees that are still green are the junipers that survived on this site, that drought. Again, just to toggle that. This is pretty extraordinary big, fast change in a system. For reasons that again I won't talk about much here, because I'm focusing on this older history for this talk and the erosion and what we did about it. Well…suffice it to say that the Jemez in general, and the Bandelier in particular have been ... We have been on the leading edge of seeing how big, fast changes can occur on landscapes with climate change-type drought. This has become a bit of a poster child landscape for research by a number of folks about how these landscapes, they get these nonlinear tipping points that can really drive big, fast ecological and hydrological change.
We're hearing somebody in the background. I don't know if that ... Here is actually the fire scar chronology from the Frijolito Watershed.
Karen:Craig, just a minute. Excuse me. If you're talking and carrying on another conversation could you please mute your phone. Thank you. Go ahead, Craig.
Craig:This is a fire scar. You probably saw a bunch of these from Chris Roos last week. Again, timelines of individual tree samples calendar years on the bottom. Each vertical tick mark, in this case, represents a fire scar recorded in the tree rings. You'll see they tend to be synchronized. Here, this is 1842 and almost every tree up there recorded fire. We know that there was enough herbaceous ground cover to be able to support spreading fires into at least the mid-1800s. Then you see it. It ceases and there has been no fire on this site since, I think, 1858, looks like was the last significant year on this site, which is early.
Here you can see it spatially. Here's a scale. This is 600 meters, the -spatial scale here. This is on an air photo. Here, the yellow outline is the Frijolito Watershed. The red trees are trees that showed a fire scar, sampled trees that had a fire scar dating to 1842. The green ones are trees that were sampled at the same time that potentially could have recorded that and did not. What you see is that this mesa - that fire spread widely across this woodland mesa top. Indeed, 1842 was a watershed wide fire year in which this is the canyon bottom. The headquarters of the park is actually right here, for those of you who know it. 1842, there was fire across from these elevations all the way up to the caldera rim, 13 miles up gradient. Fire was very widespread in that period, which requires some kind of surface fuels to carry it.
This is what that world looks like today. It's inconceivable that you could sustain surface fires. This is one strong line of evidence just about the magnitude of ecosystem change in this site.
What drove this? The fires actually stopped several decades before active fire suppression became a policy. Fire suppression did not become a policy until, subsequent to 1910, right after 1910 there was a very bad fire year. Prior to that there was debate about whether fire was a good or a bad thing in western forests. What happened prior to that, though, in the year 1880, literally that year, railroads extended down out of Colorado into New Mexico. They reached Santa Fe and Albuquerque and the foot of the Jemez in the year 1880. By the 1890s census, there were 5 million sheep and 2 and a half million cattle and hundreds of thousands of horses and burros and what not grazing in open range condition, meaning, there were no permits on the extensive public lands. Literally, they ate the grassy fields that sustained the surface fires. Fires collapsed, these surface fire patterns collapsed all across the whole region in the 1880s and 1890s. By 1900, these surface fire patterns no longer existed in this region, even though we have many hundreds of years of record.
They Jemez, actually, we've done many, many fire history studies in the higher elevation forest, perhaps the best sampled landscape on the planet, intensity-wise. Anyway, this story is quite robust. Livestock grazing, when you remove that herbaceous cover, it also has major hydrological affects. In this part of the world, the sheet erosion that we've been observing for the last number of decades here, appears to have been also triggered by that same episode of landscape-wide livestock grazing, which by the way coincided with another one of these severe drought episodes that was centered on 1900.
Basically, just as the livestock numbers peaked in the late 1800s, there was one of these multi-year drought episodes, the decadal scale drought that continued into the very earliest 1900s. Animals were starving across the landscape and numerous documentation of just how bad the range conditions had gotten. Basically, if you decrease the surface cover of plants and measure how much erosion occurs, you cross, literally, a threshold where at some point instead of the vegetation covered patches being connected, if you pull out a few too many grass plants, the bare patches coalesce. It's called a percolating network. Basically, the concept's pretty simple. Once the bare soil starts to connect when raindrops fall during our intense summer thunderstorm monsoon period, the water aggregates. If it doesn't run into anything to impede it and cause it to infiltrate, it just gathers energy as it aggregates down the slope on these connected bare patches. That appears to have happened broadly across these landscapes.
The overgrazing drove these two huge changes. It stopped the surface fires, which were regulating the vegetation, and it also triggered these episodes of erosion at a landscape scale.
This is the erosion and run off monitoring infrastructure that we had for almost 20 years in that watershed. I won't go into the details of it except to say we had 2 flumes down at the mouth. We had a remote weather station. We had sediment traps at multiple spatial scales. We were measuring vegetation cover. We measured surface erosion in multiple ways through changes in micro-topography. We did an immense amount of work on this watershed. This was the dominant thing in our summer season.
Every single precipitation event, we'd go out and re-measure ... We'd collect from the sediment traps at 3 different scales, 1 square meter, a tenth hectare and the whole watershed. We'd dig out those sediment traps and measure it. The run off was also collected. These are those 3 spatial scales. The 1 square meter, the tenth hectare ... What did I do, Karen?
Karen:What's wrong?
Craig:On my screen it's not full screen anymore. Here we go.
Karen:He just touched something.
Craig:Yeah I did, sorry.
Karen:Are you back?
Craig:Yeah. I'm back there. Anyway, point is only ... This is the same little chunk of hill slope where some of these dead pieces of wood like this, we sampled six times trying to get the best death date and the best germination date that we could. We have soil carbon measurements all across this watershed. We measured wind erosion in this watershed. Here's one of the wind samplers. The only point I'm trying to make, this one little 2 and a half acre hill slope, we had tried to understand it's current patterning process and historically as best we could using as many different methods and lines of evidence that we could. The bottom line we were seeing, these soils are not that deep here. We're talking like 15, 18 inches in most places. We're losing on the order of a centimeter a decade in the '90s when we had these measurements.
This is just some of the data. A lot of variability between years reflecting the variability in precipitation. I won't talk about this, other than to say that after ... I'll just foreshadow to you that when you standardize the erosion rate as a function of both the magnitude of each precipitation event, but also the intensity by which I mean the amount of the precipitation that arrived in either a 15 minute or a 30 minute window, because that intensity, if you get 1 inch over a 10 hour period, that's way different then if you get 1 inch in 5 minutes. Our storms tend to be closer to the 1 inch in 20 minute kind of variety. Those are the ones that do the work.
Anyway, this is standardized for that precipitation intensity of an event. What it showed is that actually ... Don't worry about the axes. This is time from the beginning of the study to the end. Notice here, that in the 2000s, the actual erosion rate started to go down. This was after the piñon trees died in '02-‘03. Particularly when they started to fall on the ground, which was surprisingly quickly, within 18 months. I'll show you why we think that.
Also, we know that this erosion hasn't been going on for another ... You couldn't have these kind of erosion rates for hundreds, much less thousands of years or this would have been stripped, would have just been a bare rocky hill slope already. Another line of evidence is that we literally have watched the channel network emerge before our eyes. Here was the channel network early in the study in '96. There was the channel network 7 years later. We're literally watching these channels, with individual rainfall events, emerge on the landscape, which is an indication that it's a new phenomenon to have that happen. There it is a couple years even after that, further proliferation.
We also could, where the big ponderosa pine trees from the 1950s drought had died and fallen, there are now in places created these log sediment dams. We figured that once that log fell and started to accumulate sediment up slope, it buried the soil profile that existed at the time the log started to do that. We had I think, like 4 or 5 places where we trenched above and below the log to look at the soil profile. You, indeed, see that below the log the topsoil had been much more removed then above the soil [log]. Again, reflecting that these high rates of erosion we were measuring were relatively recent phenomena. This is not something that's been going on for a super long time.
Then here's what these landscapes looked like. Again, these trees died in 2002, 2003. Here's what it looked like in 2004. The standard response was you got this herbaceous response in the litter mounds right underneath the tree. 2005 we finally got a wetter winter. The drought had persisted through ‘04. 2005 was near normal winter. We got pretty good herbaceous response across large areas that previously had been bare with less tree competition. Then the trees are already falling on the ground. What these things did, is they interrupted again the continuity of the bare soil. We started to see a decline in the erosion rate.
These are just measurements of that. Here was the decline in the percent of the bare soil and the corresponding increase in litter of various sorts. I think we're going to see logs emerge in this. The brown are the logs. These are the logs that had died pre-1993 that were on the landscape mostly in the 1950s. These are the channel networks as of 2006. Those are, I believe, the piñon logs as of 2006. There's more now.
I won't go into this. That's some detail and connectivity. This is an important summary slide to just visually think about this. In the last -since 1600 -we've gone through a landscape that had no trees, to a landscape that then developed an open ponderosa pine system with surface fire for 200 plus years. That then, through land use change, the surface fires stopped and it becomes a highly erosive landscape. The ponderosa pine that dominated the middle all died in the '50s drought and did not regenerate. We were left with piñon and juniper, that then all the piñon died in the early 2000s and we were left with just juniper. Now we're starting to see recovery to more herbaceous conditions again in some places.
Meanwhile, at the same time, starting in the late ‘80s, once we determined that this erosion was A.) a big deal; B.) recent enough to be tied to Euroamerican settlement patterns and this overgrazing history and the changes that brought, we started to say, “Well, is there anything we can do about it?” We worked - this is a master student, Geneva Chong, who we supported in '92 to do this work - testing in multiple kinds of treatments. Basically, we were seeing what can you do. We tested seeding, mulching, raking in the seed. We girdled trees to simulate herbicide, maybe because there might have been just too much woody competition. That's one of the issues. Mulching - here you see the straw we were testing - multiple things.
That morphed into a larger study once we had some initial results where we worked in two adjoining 100 acre watersheds, what we called the paired watershed experiment. This was a Ph.D. project for a man named Richard Gatewood. The vegetation specialist at Bandelier, Brian Jacobs, was central to all of this work. Brian's actually retiring at the end of the month. The big summary write up of this has just been accepted in, I forget what journal. Anyway, Brian has summarized all of this. Richard actually didn't get as much of it published as we would have liked. This was Brian's big summary project.
Anyway, this is much of the various kinds of measurements of the erosion and vegetation cover. What we did - these two adjoining watersheds - there was the control watershed on the west. This second watershed was treated in 1997, after 1 year of baseline studies.
The basic treatment that we had converged on was to go in and cut smaller piñons and originally, mostly, junipers and lop and scatter the branches across the bare inner spaces between the trees. When we tested that method, here is the boundaries. This is a helicopter view. This is the control watershed. This is the treatment watershed. This is, literally - looks like it was June - this would have been three months post-treatment. There it is looking down on it on the boundary between the watershed. They're standing on that boundary.
This is two growing seasons post-treatment. It's like walking from the moon to a meadow walking across that boundary, even yet today. The treatments that you see, the dead branches. You see the immense herbaceous response that occurred from that changing. What it basically does is by putting those branches down, they act as zillions of little check dams. They create the surface roughness that the water - instead of aggregating and running off - leaving a easily drying soil behind and eroding, the water infiltrates when it hits the surface roughness, and now the new live vegetation, which leaves more plant available water. More of the water is retained on site. Also, then you start getting more shading. You get changes in the micro-environment that the soil surface, where a seed, a little tiny seed - you got to think what is the environment that that experiences. You basically change the microenvironment.
Literally, with this simple treatment, no exotic ... In the end we didn't seed, our experimentation determined that the more conservative treatment of just modifying with this slash, the dynamics of water on the system, take systems that look like this into systems that look like that within 2 to 3 growing seasons.
However, at the same time that we did this work, we were right at the end of the wet period. We were starting to go into that dry period. The year after treatment of this was - we caught a nice wet year of '97. Since that we've been in drought.
Here's zooming in this nice little quadrate is an award frame, for the scale. Basically, it [inaudible 00:57:23] ramped up, existing plants got larger and many new plants established. This is what 6 years after treatment the treated watershed looked like. It was astounding. We put it on a public trail because we were pretty confident it would respond this way by that point. It made it an easy place to interpret, to bring people in.
We also supported a Master's project that looked at 6 pairs of basins, ten hectares each where we put these little silk pan stands to measure the sediment yield in the treated and the untreated. What you find is after treatment sediment accumulation dropped 100 fold at that spatial scale. It works.
The diversity and productivity of every biotic group we looked at from butterflies to grasses, birds, surface-dwelling arthropods, those all increased in both diversity and abundance. This system's not surprising, the base of the food web. The herbaceous part of the system greatly increased the productivity.
The whole process, the Park Service was close to ready to go, about 2000 to do this and then the Cerro Grande fire happened. That truncated the leadership of the park for some time. It was a success on the part of some of us who survived that transition to just keep this project alive and on the burner of the incoming superintendents. In 10 years, the park had 8 superintendents from the period from 2000 to 2010. You all can imagine what that would be like a little bit.
Anyway, by about 2005 it was back on the radar screen. There was a multi-year Environmental Impact Statement done to consider treating up to 5,000 acres in Bandelier. Most of that is in congressionally-designated wilderness, again, to remind you. In August, that EIS went through and we began the full scale treatments.
Just a comment about that, I would say that ... This was, and remains, a quite unprecedented project because the minimum tool that was determined necessary to implement this project was a chainsaw. This cutting, involved cutting small juniper stems and lopping them into pieces, then hand scattering them in congressionally designated wilderness in a National Park unit. It was about 4,800 acres treated, most of that in wilderness.
Here you see that vegetation map of the park and it's immediate joining areas. This will show the ... Sorry, to back up again. Again, just to remind you, these orange areas are the mesa top woodlands at the lower elevation mesa tops where the treatments are ... That's where the issue was. That's where this project was about.
Here you see the years, I'll just toggle through where the treatments occurred. This was that treatment watershed. That's 100 acres right there. That was done in '97. A decade later, we started the actual treatments for the project. There's '08. Actually '09 happened. These all happened, too. These are old slides, sorry. I recycled part of an old show. In the end, it was close to 5,000 acres were treated and it was done as of September 2010, the project was implemented.
When you go into these areas, not every acre is treated within this. If you zoomed in there would be another whole mosaic - areas that where the soils were too far gone, or the soils were skeletal, or they were too much rock exposed. It was too late. Pumice soils were not treated with a few exceptions. There's two different substrates, these old alfisols of the tuff that were these 100,000 year old soils. Then there's a really porous, coarse-textured soil layer of air fall pumice. The erosion was not a big issue in those. Those already such high infiltration rates.
A whole array of monitoring in there to determine the success of these things. This work is ongoing and continued. It doesn't get done every year but we have baseline and all these places. There have been some re-measurements, enough to have some indication of the success. Quite a few archeological sites that have been monitored within there as well.
From pre-and post-treatment, there's many more archeology sites then this within the treatment zones, but these are the ones where there's been formal monitoring of the change in erosion on the cultural resource sites.
Again, nearing the end here, just as a reminder, this is the Bandelier Wilderness boundary. There are some areas of woodland here outside that boundary. Then in the outlying unit, the Tsankawi Unit, that's not wilderness. It was that combination, I'm quite confident this project would not have, at least it's much less likely it would have been improved and there would have been the energy to see it through if it was just a natural resource issue, if it was just about accelerated erosion. The fact that it was both a cultural and a natural resource issue, and that it was impacting the cultural resources for which the monument was designated. This is actually within the Wilderness Act, this was the part that supports the intervention in an untrammeled wilderness, in an area. We were not trying to restore a particular structure of vegetation. It's not like we're not trying to get it to 32 stems per acre of a certain size class. What we were trying to restore is the process, the natural processes that had been interrupted. The balance between surface cover and run off and erosion processes, and the feedbacks to the vegetation that come from that and, ultimately, the feedbacks with surface fire, again, in the system.
It was done with some discomfort on our part. Brian Jacobs and I, in particular, were the two drivers of this thing. Yeah, we're fully aware, we've left fingerprints, hand prints at some level on that wilderness landscape. juniper stumps - we're only cutting small stems out there - but they don't decay rapidly at all. They're quite persistent. People use them as fence posts for that reason. There are a number of uncertainties in terms of how this system will respond. It was framed in a restoration framework. We called it an ecological restoration project. You can't go back to where it was. The best part of those soils had already been lost from those affected areas. The system, just from that alone, couldn't go back. Of course, climatically we're moving into no analog terrain fairly rapidly. We're pretty much there in the Southwest in recent years.
We may get a reprieve, by the way, in the Southwest because sometime in the next decade, the Pacific should slosh back to the warm phase in which el Nino conditions would be more prevalent again. We may actually get a wetter and thus a bit cooler window again for a bit. By mid-century it'll go back again. At that point it will be pretty difficult, probably, for a lot of the current vegetation in this landscape. We've seen a foreshadowing of what that can look like. If it's another degree Celcius or two warmer, by the next big drought episode, we'll see another round of this.
In the meantime, I'm thinking there's going to be a good window to do treatments of this sort and it gets things in the higher forest types, the kinds of things it seems like Chris talked about last week.
Anyway, it's amazing. The most negative ... We went through an EIS process with public meetings, multiple public meetings in the cities of Los Alamos and Santa Fe. The most two negative comments received on this project were from Brian Jacobs' daughter, a grade school student who sent him a drawing that said, "Please save the trees, Dad."
And from a Park Service regional wilderness manager who just, philosophically, didn't like the idea of intervention, deliberate intervention, in a wilderness area, even though our bases for that were that the system was far from natural. It had been intervened in, deliberately and inadvertently, many times previous and thus it was out of whack, in a sense.
We brought in the three... The Bandelier Wilderness was congressionally-designated in 1976. We put that paired watershed study in a place where it would be easily accessible. It was in the wilderness, in the edge of the wilderness. We brought the three godparents of the Bandelier Wilderness in actually on the same field trip. We spent the day, along with others. We had the Park Service Wilderness Steering Committee in there on the ground, at least once, maybe twice, given the delay in the project.
We go through our best understanding of how this landscape had changed through time, what our evidence for it was. Some of these uncertainties, we were very clear about what we did and didn't know, at least our best understanding of it. At the end we would ask people and then you would go out and look at the treatment. It's such a dramatic treatment effect. The end question was, what would you do if it was your responsibility to manage this with a Park Service mission, or a mandate, to maintain these resources "unimpaired"? How to best balance those things? We had that conversation up front before the EIS process. We brought in the people most likely to object, the Wilderness Society. We brought in various wilderness people, the New Mexico Wilderness Alliance and the Wilderness Society, and various other environmental groups. We brought in many of the locals who loved and love still, Bandelier and its wilderness.
In the end, people thought we were taking the responsible course of action. Nonetheless, there are these uncertainties and, thus, the monitoring should continue. This is just some of the new work by the Southern Colorado Plateau INM program at putting a new set of plots in the last half dozen years that are part of it.
The last slide I have is just a little bit of a shout out, actually, to the crew members. Here actually is Rory Gautier who just retired last summer. Archeologist extraordinaire. He grew up in this landscape. Rory was great, directly overseeing the treatments, sure there weren't impacts from treatments on the archeology sites that we didn't want. We did treat over most of the archeology sites in the sense of cutting out trees we didn't want, that would not have been there, except for the absence of fire, and spreading some slash around, particularly the margins of the sites.
These crews, I want to just mention, it was contracted out. This is a guy named Noel Aquino from the state of Oaxaca in southern Mexico. All the crew members were mostly, probably, illiterate. Certainly I speak Spanish well enough to really enjoy interacting with them out there. Noel so understood the prescription of what we were trying to achieve. He moved faster than we could. Anyway, I just wanted to recognize just how hard, and how fast, and how well the quality of the work that they did. It wouldn't have happened without that.
I think that's enough. I think I'll stop. One more thing I'll just say is that ... I didn't think about that until it was just a little too late today, but that was through 2010 this treatment was implemented. We been in severe drought since 2000 onward with, literally, since 2000 there have only been 3 years where we had close to average long term mean winter precipitation. The ‘11, ‘12, and ‘13 have all been very dry. ‘14 we've been close to average again. In 2011 there was extraordinary fire. The Las Conchas fire that burned 156,000 acres in the landscape including 2/3 of Bandelier's area. It did burn over, I think it's 23% of the treated area, so there's another variable in the mix. The intention has been to keep fire out of the treatment areas for at least a decade to allow the perennial herbaceous vegetation to increase enough. We don't want to burn up the woody slash too soon because that's really a form of biological capital. We only get one shot at that on these fairly low productivity sites.
Anyway, on a little over 20% of the treated areas, it did burn. We've been monitoring the effects of that as well. The story will continue. We're clearly in this era, the Anthropocene. We're on a trajectory. We're not going back to that historic range of variability any time soon it doesn't look like if the climate models are at all right.
Anyway, let me stop there. If people have questions or whatever, glad to discuss further.
Karen:Craig, thanks for a great talk! Do people have questions and comments?
Jim:Craig, this is Jim Kendrick. I'm up in the Northeast Region now, but I was out at El Malpais during the time frame that you're talking about there. You've done a remarkable study and the team at Bandelier's done a fantastic job there. It's just remarkable to see. I remember traveling back to Bandelier during one of those years right around the piñon die off. It was so dramatic, it was difficult to recognize the landscape from what I had known in the past. Now to see it graphically, and with all the data you have, is just tremendous. Great job.
Craig:Thank you. Again, there were a lot of players involved. Thanks.
Jim:I’ve gone up with Rory to see some of these areas. We did something writ small and certainly not as scientifically rigorous out in some portions of El Malpais off the lava that were pretty successful, too. It was good.
Karen:Go ahead.
Speaker 4:Hi Craig, this is Chris Roos.
Craig:Hey, Chris!
Speaker 4:How are you?
Craig:Good.
Speaker 4:I wanted to ask you about the conditions before the 17th century germination and regrowth in Frijolito. How much, particularly in light of the absence of major erosion after the Ancestral Pueblo occupation do you think that the human use and deforestation and agricultural use of that landscape interfaced with the 16th century mega-droughts? I guess, contracted with the grazing impacts, what those two different, fairly intensive, use scenarios meant for the erosion and hydrological history?
Craig:It gets a bit speculative. If you want to come out and investigate on small basins, Chris, we would love it. Try to get some, see what resolution might be attainable. What might have been happening in terms of sediment dynamics in little basins or things there. The way I envision what happened there in the 1500s, is that the Ancestral Puebloan folks had ... The weighted component of that system was squeezed pretty low by that point, by the mid -500s. I don't know about exhaustion of the soils. Bob Powers is still trying to sort some of that out, trying to finish off a dissertation. I don't think he's quite finished it yet.
I think that what was holding the soils together was not trees. It was the herbaceous cover, the things that were providing the fuel connectivity for surface fires, which, admittedly, were lower frequency down in that zone then they were just a little bit further up-mesa when you get into the ponderosa pine, more into the heart of the ponderosa pine zone. The fire frequencies are substantially greater in the tree ring record.
We're getting down to this zone where fuels probably were limiting. That's climate mediated in part of course down there. The way they conducted agriculture with digging sticks, I don't see them ... I don't know, tell me if I'm thinking wrong about this. In terms of interrupting, I don't see them creating big sloughs of bare soil, connected bare soil, in a way that would have promoted a big pulse of erosion. I'm sure there were localized patches of it. That's my sense. Then the 1580s mega-drought there. The thought around here is that was the last straw that pushed people off. You don't see tree ring cutting dates in the few that we have from the Pajarito Plateau, from the Bandelier part of the world. There's very few after 1550; there’s a couple. There's nothing after 1580. That seemed to be the last thing, the last straw in it. Then, of course, the Spanish arriving, and missionized and colonized that part of the world right then in 1598. The whole sequence is altered after that.
Was there something else? I'm not quite sure what you were fishing for there.
Speaker 4:I've got a lot on my mind. I don't want to take up everybody else's time. Maybe you and I can chat again at some point.
Craig:Yeah, be pleased, of course.
Speaker 4:Thanks for a great talk too.
Craig:Thank you.
Speaker 5:Craig, this is Helen Farely I had a question. I guess it might have been related to Chris's but you'd mentioned early on ... This was the main question. I'm curious about it that it was speculation that it was deforestation that had reset the landscape in the 1600s. It would sound to me like what you just said a moment ago, suggests that there really isn't direct evidence for that. That might be more speculation then actually based on evidence for extensive cutting of beams or whatever during that period.
Craig:That's true! For sure, that's true. The other thing, and I didn't say that, but the 1580s, that's been the index mega-drought for the last millennium. The late 1200s, the 1280s, and the 1580s are thought to been the 2 worst droughts regionally, more or less, until perhaps the one we're in now, which is being amplified in severity, from a plant perspective, by the warmer temperatures.
In any case, the 1580s drought was severe enough, almost certainly, to have killed lots of trees as well, in systems. There's some, again, indirect evidence of that when you look at tree ... Peter Brown and Tom Swetnum 20 something years ago just looked at all the tree ring samples from the Southwest region that were in the tree ring lab archives at that time, in their databases, and looked at how old trees were. What you find is, you can find lots of trees, many trees, 400 years old. There's lots of trees that old in the Southwest. Pushing back right to that late 1500s drought window. Then the number of trees that people find to sample drops precipitously. Then there's a really long tail that goes back for hundreds of years.
These trees can live many hundreds of years more than 400 years old. It looks like a lot of things didn't get through the late 1500s drought. Like a lot of these things, it could have been interactive. If you think about how much wood people would have needed to use, again high densities, high numbers of people, for centuries doing swidden agriculture, probably using fire as a tool to clear the canopies. They're not growing. Their staple foods are all a very light-loving. They need it to be open. They're all things you cook, corn, beans, and squash. You need fuel wood. They're living in stone structures on mesa tops that are quite cold in the winter time. You're heating.
It's actually hard to imagine how they could NOT have deforested those mesa tops over that time period. These trees don't grow that fast. Again, the age structure, and it's not just in that one hectare. We don't find old piñons anywhere on these mesa tops that go past that window. Again, there's some confounding effect there. I think of that late 1500s mega-drought. Maybe that took out ... There should have been young trees that got through that, that would be 500 years old today. Whereas at the Mesa Verde you can find 600-700 year old piñon. You find piñons that established in the century after that landscape was abandoned, which in there there is some better archeological evidence like changes in fuel wood found in hearths and things through time indicated that fuel wood scarcity was emerging in that part of the world up there in the Cortez and Mesa Verde kind of regions.
Yeah, we don't have some perfect smoking gun for that.
Speaker 5:Can I ask one other real quick question. You mentioned that in follow-up to doing all this treatment you have a sample of archeological sites that are being monitored for erosion control.
Craig:Correct.
Speaker 5:Can you just very, very briefly because I know people have other questions but, one, either give me an overview of what's involved in that, or two point me to where I might be able to find more information about-
Craig:Can you send me an email and I will send you the report that was completed recently.
Speaker 5:Okay, that'd be great.
Craig:On that work. That would be, by far, the best way to do it.
Speaker 5:Thank you so much. I really appreciate it. Excellent talk. It was fascinating. Thank you.
Karen:Craig, do you have a link or a URL for that report? I can also post it along with the webinar.
Craig:I don't have a URL for it, but I could send you a copy of the PDF and you could post it easy enough.
Karen:That’s true. I can scan it and post it. If you want to do that I'd be happy to post it for you. I think that these are topics that are going to be a wide interest as we grapple with some of these same issues.
Description
Craig Allen, 12/23/2014, ArcheoThursday
Duration
1 hour, 28 minutes, 11 seconds
Credit
NPS
Date Created
12/23/2014
Copyright and Usage Info