Tree Rings, Ecology and Culture in Mongolia
Neil Pederson of Lamont-Doherty Earth Observatory is out there – that is, out beyond where human beings generally tread, in the remote forests of Mongolia. He and colleagues are collecting tree rings to recreate a 400-year history of climate and wildfires. They hope to better understand the influence of climate on fires and ecology. Pederson is blogging about the expedition and his impressions of Mongolia and its culture.
Kristen de Graauw and Cari Leland
Cari and Kristen here, checking in from Mongolia. This year we were invited to be instructors for the Third National Dendroecological Fieldweek, May 23-29 in Udleg, Mongolia. We arrived to Ulaanbaatar on May 20th so we were fortunate enough to have a few days to recover from some pretty terrible jetlag before beginning the fieldweek marathon. Anyone who has ever attended a fieldweek anywhere in the world knows how challenging (and rewarding!) these events can be. Our first few days of the fieldweek were spent at the NUM (National University of Mongolia) research station near Udleg, a few hours north of UB. We were so happy to see the beautiful countryside for a few days. We got to ride there in this awesome Russian vehicle, which Cari nicknamed Herbie.
The research station was a complex of buildings for housing, a kitchen, and lecture rooms. We shared a cozy room for two and enjoyed beautiful views of the valley and mountains surrounding us.
After everyone settled in, we met for the opening ceremony. Baatar gave a nice introduction of the project and the history of the CEME collaboration. There were 8 students in total, and 7 of them were female (girl power!). There was a good mix of participants; from first year undergraduates to PhD students.
After the opening ceremony we went out to the field. Baatar gave us a guided tour of all the current research projects at the station (there were many!) and the potential sites for the fieldweek. Then we gave a quick lecture on the basics of dendrochronology and headed back towards the research station to discuss potential fieldweek projects.
Day 2 at the research station was field sampling day. Unfortunately we woke up to a cold and rainy day but that didn’t stop our groups from heading out into the forest. After a long discussion we decided Cari would teach the Climate group and Kristen would teach the Ecology group. Cari’s group headed up the mountain in search of old larch and pine trees to core while Kristen’s group went to a portion of the forest that had been logged. The goal for the climate group was to find moisture-stressed trees and look at the relationship between tree rings and climate. The ecology group’s goal was to determine logging dates and the effects on surviving trees.
After one of the coldest and rainiest field days we’ve ever experienced we headed back to the field station to thaw and dry ourselves and the cores.
While we waited for the cores to dry, the students practiced skeleton plotting.
The next day we mounted the cores with glue and taught the students how to sand. They quickly learned that a well sanded core took time, patience, and persistence. At the end of the day we headed back to UB to begin laboratory methods.
Back at the university we had to hit the ground running with lab methods. The students skeleton plotted the samples from the research station one day, learned how to do the list method and measure the next day, and finally on the last day they learned how to run COFECHA and read the output files. It was challenging but everyone worked their hardest. The final day was very busy. The students were working on their presentations until the very last minute. The groups did an outstanding job presenting their projects, which made us feel so grateful for being able to teach such a bright and dedicated group of students. During the closing ceremony Baatar gave us both a really nice Mongolian tree and shrub guide book and then presented each student with a certificate of achievement. The students then gave us the most thoughtful gifts of Mongolian art and script.
Armin Van Buuren, Ancient Wood, and Ghengis Khan: This is not your father’s field research in Mongolia
We never expected this. Enkhbat had us hovering at warp speed along the Millennium Road in the northern shadows of the Khangai Mountains. Armin Van Buuren’s A State of Trance filling our rig. We were starting a new project to study the interaction between climate, fire, and forest history in the land of Chinggis Khaan and a silky voice was lifting us higher, “and if you only knew, just how much the Sun needs you, to help him light the sky, you’d be surprised. Do…do…do.do”. We were exhilarated. The Sun was shining. This was not exactly Chinggis’ steppe. But little did we know, we would eventually be chasing his ghost.
Byarbaatar & Amy in front of Khorgo, unknowingly about to meet Chinggis’s ghost. Photo credit: Enkhbat.
After about a day’s travel we started passing the Khorgo lava field. Amy asked, “What’s that?” Neil had forgotten about this landmark despite having walked upon it 10 years prior. It is a ~30 km2 lava field with old trees on it. Gordon Jacoby, Nicole Davi, Baatarbileg Nachin, and others had sampled in the early aughts and put together a ca 700 yr long drought record from Siberian larch. Neil relayed this information to Amy and she said that we should sample on it knowing that a 2,000 yr long record in the American Southwest had been produced on a similar landscape feature. We had a tight schedule, but as we drove out to the western edge of the Khangai’s, sampled sites, witnessed a sheep in the dying throes of a brain worm infection, got snowed on, and then sweated in much warmer temperatures, we decided it was worth the time to see what was out there. Little did we know.
By the time we arrived to start sampling, Neil was getting sick (we learned days later that Neil was coming down with tonsillitis) and we were on fumes from some bone-challenging swings in the weather. Amy pushed on during the first day with Byarbaatar and Balginnyam. The found a pile of dead horse bones and couldn’t get the chainsaw running stopping them from acquiring samples from downed, dead trees. It felt almost hopeless.
We summoned our strength the next day and explored a new section of the lava field. Soon after getting out there we starting seeing Siberian pine, a tree Neil hadn’t seen on his first visit and hadn’t been sampled previously at this site. We decided that after our fire history collection we would sample some pine trees just to see what They might have to say.
The Logo Tree: The Siberian pine that clued us into the possibility that there might be something extraordinary on the Khorgo lava field. Photo credit: Amy Hessl
As this collection wasn’t priority, these samples sat until late January of the following year. Here is the first email of the discovery (partially redacted for some sensitive language).
The sample “locked in and said the inner ring i measured was 1235…whoa! that was cool b/c i started a good bit from the pith…. i race back to me scope and measuring stage…..make mistakes. going too fast. fix the mistakes…..the PITH is 1142!!!!
yes, i can see the yr Chinggis was born. i can see the yr he died. i can see the yrs Mongolia rose to rule Asia!
this has been our Holy Chinggis during the entire Mongolian project.
this is totally hot
ps – i guess we are going back to Khorgo, huh?”
KLP0010a – the first sample of Siberian pine from the 2010 Khorgo lava collection to break the 1200s. The pith is 1142 CE (Common Era). Photo credit: Neil Pederson
We secured funding and we went back to Khorgo in 2012 with a bigger crew and one goal in mind – collect more wood.
We cannot believe what we have found.
For centuries, common wisdom held that the Mongols were driven to conquest because of harsh conditions – drought. Our new record, dating back with confidence to 900 CE (Common Era), indicates the opposite. After the unification of the Mongols, Chinggis Khan, you know him as Ghengis Khan, led his army from Northern China in 1211 to the Caspian Sea in 1224 CE. Our new record in PNAS indicates that it was consistently wet from 1211-1225, a period we are calling the Mongol Pluvial (look for an open access version of this paper here or contact Amy or me). No years during this period were below the long-term average, which is a singular rare run of moisture conditions in our 1,100 year long record. Independent tree-ring records over extra tropical Asia also indicate that this period was warm.
On the cool semi-arid steppe of Central Asia, water is life and in those days, water was energy. The Mongol diet is heavily based on the meat of grazers. Their mode of transportation was the short, but Pheidippidic horse. So, for food and for travel, grass is life. Grass is energy. An abundance of moisture would seem to provide the horsepower for the rapidly growing Mongol Empire. The Mongol soldier had five steed at their disposal. With a large army, that quickly translates into a huge herd and a huge need for grass.
Our tree-ring record suggests that the grasslands of central Mongolia were likely productive. They strongly agree with satellite estimates of grassland productivity. Going back in time, then, the trees would suggest the Mongol Empire during its rapid expansion was sitting in a sea of grass, a sea of energy, a potential abundance of life.
That is our hypothesis, anyhow, and something we will test in the coming years with historical documents, environmental records from lake sediments, more tree rings, and ecological modeling experiments.
While this record speaks to a rapid transformation of Eurasian culture during the 13th century, it also speaks about an abrupt transformation in Mongol culture today. Towards the end of our tree-ring record we see a prolonged drought from the end of the 20th century into the beginning of the 21st century. This drought followed the wettest century of the last 11 and occurred during the warmest period of the last 1,100 years in Asia. The abrupt transition in the environmental conditions, a transition that saw hundreds of lakes and wetlands disappear from the landscape, occurs during the transition from a more agriculturally-based economy to a more urban-based economy. These severe conditions, in combination with some harsh winters, killed millions of livestock and are thought to be one trigger of a mass migration of Mongols from the countryside into the capital of Ulaanbaatar.
Ulaanbaatar in 2006. The homes on the far hills likely reflect climatic and economic refugees moving from the countryside into the city. Photo credit: N. Pederson
Though we cannot connect this heat drought to climate change (though maybe we kind of can), warming temperatures have stacked the deck towards higher evaporative demand, so even if the amount of precipitation remains the same, high temperatures will generate a more intense drought. That’s what we observed in the early 21st century and based on past moisture variation in Mongolia and future predictions of warming, we would expect to see similar events in the future.
From Armin Van Buuren to Chinggis Khaan to Armin Van Buuren again. We had no clue of how Summer 2010 would light the sky.*
* this post was requested by a media outlet so they could have the ‘author’s voice’ on this discovery. That version was ultimately sanitized for your protection. Here it is unadultered.
It has been a while since we last updated this blog. The reasons are many. The primary reason for the delay is that we have had singular focus in launching our next project, a project that for many is a dream come true.
Before we launch into that and officially start the 2013 field season, let’s do a quick recap of our team’s efforts since last August.
Our academic year started with a bang: our new research project, which was an unexpected off shoot of our efforts to study climate, fire, and forest ecology, was funded by the National Science Foundation in September 2012.
Since then, our team has spent much time presenting prior results, new preliminary results and processing samples. Many, many samples.
First, kudos to Nicole Davi work improving a tree-ring based reconstruction of the Kherlen Gol in Mongolia (gol = river). Many of the chronologies used were collected between 2009 & 2011 as a part of the Climate, Fire, and Forest Ecology project. The new work, “Is eastern Mongolia drying? A long-term perspective of a multi-decadal trend” can be found here.
Second, we need to congratulate Cari Leland on persisting and publishing the first paper from her thesis: “A hydroclimatic regionalization of central Mongolia as inferred from tree rings “ – link
Cari’s effort set the stage for our second paper on the climate history of the Mongol Breadbasket: “Three centuries of shifting hydroclimatic regimes across the Mongolian Breadbasket“ – link
Finally, Tom Saladyga got a nice piece of his dissertation published with the article, “Privatization, Drought, and Fire Exclusion in the Tuul River Watershed, Mongolia“ – link
We have a few manuscripts in development from our Climate, Fire, and Forest history project, which ends in 2013. And, we are very happy that Byambaa is on the doorstep of completing her dissertation. This project is coming to a very nice completion and we are thrilled.
We are equally thrilled with the start of our new project, “Pluvials, Droughts, Energetics, and the Mongol Empire”. We’ve gotten a silly amount of press here, here, here, here, and here – it has been great. Both institutions have made nice videos and overviews of the project: here is an example of WVU‘s and here is LDEO‘s. Awareness of this project has been widespread. We meet new scholars from various parts of the world and it seems they are already familiar with the new study. Neil presented preliminary results at the PAGES meeting in Goa, India – that was hard work
Amy Hessl garnered two invites based upon our work. The first was a workshop primarily populated with historians on migration and empires across Eurasia. The setting and out-discipline experience was fantastic. The second was an archeology-based workshop on Chinggis Khaan in Jerusalem – sounds like that was equally hard work!
We are now gathering in Ulaanbaatar to launch the first season of ‘complete’ field work. By complete fieldwork, I mean that we will not only be collecting tree cores and cross-sections from dead trees, but Avery Shinneman Cook will be leading the effort in collecting lake sediments in central Mongolia to better understand long-term environmental history and the impact of the Mongol Empire on the landscape in and around the ancient capitol, Karakorum.
Prior to that, we will hold a 4-day workshop introducing ourselves to our wonderful and diverse team (a dream team? Besides Amy Hessl and Neil Pederson, team members include: Baatarbileg Nachin, Hanchin Tian, Nicola Di Cosmo, Avery Shinneman Cook, Kevin Anchukaitis, Oyunsanaa Byambasuren, and PhD students, Caroline Leland and John Quinn Burkhart) and their specific research. We will visit historical sites and lakes to begin the discussion on how to address some questions originally posed in our grant: did the rise of the Mongol Empire, driven literally by horsepower, benefit from an abundant climate and a surplus of ecosystem energy? Did the construction of the Mongol population, army, and herds of grazers significantly impact the landscape? Answers to the ful climatic context of the Mongol Empire has been a primary goal of the Mongolian-American Tree-RIng Project, (MATRIP) since the mid-1990s. We finally have the chance to address these questions. We do not know the answers yet, but stay tuned.
Brief Observations on an alternative approach to Mongolia:
This is my 9th trip to Mongolia. It is hard to believe that I have visited this far-away land so many times. But, when I smell the steppe as we enter the airport, I relax and hit a new mode that is akin to putting on old slippers. I go through customs with nary a concern knowing that Baatar will be waiting for me with a warm greeting and hug. The drive to UB is filled with the same conversation – “How are you? How is Mongolia? How are things going? How is your family? How are your students? My, Mongolia has changed“. It is wonderful.
What changed for me this year was how I got to Mongolia. I typically venture west and enter through eastern Asia. This time, I traveled east, stopping in Turkey, re-fueling in Bishkek, and then flying over western China and western Mongolia.
The sky was clear upon entering western China and the scenery was stunning. Really. I stopped my movie and just drooled out the window [akin to a dog?]. It adds a few hours of travel time at most, but I’d do it again.
Scenes of Going East to go East