In a country with nearly 1.4 billion people, finding untouched natural beauty can be difficult. Yunnan has more wild places than most of the rest of China and that is a major reason why so many travelers come here, and why many of them stay. It is then more than a bit disconcerting when reports surface that climate change is drastically altering some of the province's most beautiful places.
China Daily recently compared photos of Yulong Xueshan (玉龙雪山), or Jade Dragon Snow Mountain, that show its once mighty glaciers are disappearing rapidly. Although this is not particularly new news, it is a stark reminder that natural beauty, even on mountaintops, is not permanent.
Disappearing glaciers are more than just the loss of a good photo opportunity. When temperatures change and water becomes more scarce, plants and animals are affected. Eventually the effects on an area's flora and fauna impact people as well.
In an effort to better understand those changes, Robbie Hart has been conducting field research on the rhododendron populations of Yulong Mountain outside of Lijiang. He has been observing the plants since 2009 for his doctoral dissertation and is comparing his findings with those of other, older botanists — particularly Dr Joseph Rock, George Forrest and Baron Heinrich Handel Mazzetti.
Hart is a PhD student at the University of Missouri — St. Louis and the William L. Brown Center of the Missouri Botanic Garden. His goal is to compare data he collects with that of preceding botanists and tease out the effects climate change is having on some of Yunnan's most famous flowering plants.
GoKunming recently spoke with Hart to find out what he has been up to, what the rhododendrons are telling him and what he shares in common with the plant hunters of the early 20th century.
GoKunming: How are you funding your research and what institutions are you working with?
Robbie Hart: I'm working very closely with Dr Xu Jianchu at the Center for Mountain Ecosystems Studies. He and Dr Sailesh Ranjitkar are doing similar monitoring projects and historical comparisons in the Gaoligong Mountains (高黎贡山) and Nepal.
And, of course, the researchers and staff at the Lijiang Alpine Botanic Garden are good friends and their help has been indispensable in my work. The field station in Lijiang is actually co-run by the Kunming Institute of Botany [KIB] and by the Royal Botanic Garden Edinburgh, which has had a relation with the area ever since Forrest began collecting here 100 years ago.
GK: Is there anything specific about rhododendrons that make them the focus of your work?
Hart: Pretty much everything about rhododendrons makes them work for this study – the excellent herbarium record, their diversity and cultural and ecological importance to the region, and their spectacular flowering. All of these make it possible to not only do the research, but to communicate about it to people who may not be terribly interested in climate change, but do enjoy beautiful plants.
GK: Are you focusing on one specific geographic area or mountain, or checking on rhododendron populations in multiple places?
Hart: I'm focusing on Yulong Mountain, because it really is the best for historical collections, and because of the proximity of the field station. My transects extend from the villages on the Lijiang side of the mountain to the south summit of Yulong at around 4,200 meters, and then down the Jinsha River side.
GK: How much time do you spend in Yunnan each year?
Hart: I'm at the mercy of the rhododendrons, which, between all the species, have a very long flowering span. The earliest species begin flowering in February and the latest don't finish until August. So I'm usually here at least eight months out of every year.
GK: This seems like a long process involving painstaking research. You began coming to Yunnan in 2009, how long do you think you will continue this field study?
Hart: I certainly think about the pains involved during the thunder-hail storms on top of Yulong! Just my luck to pick a species that flowers through the monsoon. But I realize that I'm incredibly lucky to work in such a beautiful and biologically rich place. I'll be finished with my PhD research after 2013. Then I'll go back to St Louis to write up my PhD.
Rhododendron flowering is proving to be an excellent barometer of climate change, and I hope the monitoring project will continue after I leave Yunnan. KIB has been a valuable partner throughout my research, and they are perfectly positioned to continue the monitoring that I've begun.
GK: What does your research indicate about climate change?
Hart: Well, my research is more about the impacts of climate change on plants and people, rather than about the dynamics of the climate itself. However, the weather station data from Yunnan show a dramatic increase in temperatures, especially in the last 30 years.
An individual drought or storm can't be linked to CO2 emissions, but it's clear that climate change is directly linked to increases in variability and extreme weather, which we've certainly had our share of the last few years in Yunnan.
My research makes it clear that even gradual change can have a big effect on the plant diversity that is such an important part of this area's natural heritage, forcing plants up mountains, and disrupting flowering phonology.
Rhododendrons are just one example of this, but they are also one of the main food sources for bumblebees and other pollinators in the springtime. Even subtle climate change affects them and has the potential to ripple out to other species.
GK: What is your general methodology?
Hart: Essentially, it is many different ways of getting at the same thing — long-term climate driven change in the rhododendrons of Yulong. So this can be just looking at the herbarium record, and comparing elevations and times that rhododendrons were flowering in 1911 versus 1981.
It can also involve comparing the herbarium data to the data I'm collecting on their flowering times and elevations in 2012 or to local peoples' perceptions of change in the last fifty years.
I try to specifically address the way climate is driving this change through working with Chinese weather station data, which goes back to 1955. I also use a tree-ring chronology I'm building, which will extend back to the turn of the 20th century. To simulate future climatic warming I also conduct elevated-temperature experiments in greenhouses.
GK: What are some general conclusions you can draw from your research up to this point?
Hart: I'm still gathering data and during the winters working furiously on analysis. It is clear that rhododendrons in the greenhouse, and those lower down on the mountain, do begin blooming earlier than they used to — exactly what we'd expect from warmer temperatures.
However, when looking at the long-term data, the mean peak flowering time is actually getting later, even though the climate change driven rate of increase in temperatures here is greater than the global mean! We still don't know exactly why this is.
It's certainly connected with, but not entirely explained by, an upslope movement which we can also see from the herbarium data. That is to say, rhododendrons are now growing on average several hundred meters higher than they were in Joseph Rock's day.
All of this might also have to do with plant physiology: some rhododendron species need to reach certain temperatures in the winter before their biological clocks 'know' to start expecting spring. However, this isn't an isolated effect. The jury is still out, but I'm excited to see the results when I finish my data gathering and analysis.
GK: How many species of rhododendron did Rock collect and which species are you focusing on?
Hart: Rock and the other early collectors like Forrest and Mazzetti, gathered literally hundreds of species of rhododendron from Yunnan alone. They also explored Sichuan, Tibet and Burma for rhododendrons and other plants, of which they collected in huge quantities. By the time Rock left China, his collection numbers were in the tens of thousands.
I'm focusing only on the 30-some rhododendron species that are found on Yulong Mountain. That is plenty! It means that I have hundreds of plants on Yulong that I hike to every two weeks, and more than 12,000 historical herbarium sheets that I photographed.
GK: Where are Rock's plant collections stored and where are yours kept?
Hart: Rock was chronically short of funding and constantly looking for other sources — actually this doesn't sound unfamiliar. Anyway, Rock would send his specimens primarily to whoever was currently footing his bill.
This means that his specimens are spread in herbaria across the world – from Kunming and Beijing to Vienna, Edinburgh and Cambridge, Massachusetts. My first task was visiting a great number of herbaria to find and take pictures of all the rhododendron specimens that exist on Yulong Mountain.
It was not always an easy task – organizational systems can differ or be lacking, access is not always easy (somehow, I ended up locking myself out on the roof of the British Museum), and herbaria can be massive. The Missouri Botanic Herbarium, where my plants are primarily kept, has more than six million specimens.
Luckily for me, all these specimens have labels, and Rock, like other responsible botanic collectors, gave every specimen he collected a sequential number. So if a label or specimen is incomplete, I can match the number with entries from Rock's field book and with then find duplicates of the specimen that might have more complete labels.
GK: What led you to Joseph Rock's plant collections?
Hart: I've had a life-long interest in the environment and in the ways humans preserve knowledge, and in the connections between the two. At the moment, my PhD work allows me to divide my time between Yunnan mountaintops, interviews in local villages, and paging through century-old plant collections in the British Museum.
I came to my PhD project knowing that I wanted to address climate change in a novel way, work in northwest Yunnan, and incorporate indigenous knowledge.
Other researchers at the Missouri Botanic Garden, including my advisor Dr Jan Salick, had previously done work on long-term dwarfing of Yunnan's medicinal Snow Lotus using herbarium specimens.
Because almost all herbarium specimens are taken while the plant is flowering, I realized that I could take a similar tack in addressing long-term change in phenology and distribution of mountain plants in Yunnan. I knew that to do this, I would need a very large record of collections The choice of rhododendrons, and of Rock, was obvious.
GK: Did Rock note elevation, latitude and longitude and was his data detailed enough to make exact comparisons with what you observe today?
Hart: This is a reasonable concern. Because Rock and other plant collectors weren't ecologists trying specifically to address the questions I'm addressing, their data is idiosyncratic and statistically untrustworthy.
It's true that they certainly weren't systematically randomizing their collections. However, for my purposes, they also weren't systematically biasing their collections. What they were doing was collecting hundreds and hundreds of specimens, with precise notes on date, elevation, and location of collection. Although the statistics have to take into account the non-random nature of the data, the sheer bulk of information makes it usable.
In fact, the specimens have some advantages over ecological information, the most important of which is that they still exist as physical objects, rather than just as data. So even though the original collectors may not have thought a specimen's flowering state was important, I can extract that information simply by looking at the specimen.
Hart: You've hit directly on my insecurities here! I wish I'd had more time to really master each of the Naxi and Yi dialects spoken here. One component of my research is ethnobotanical in nature — trying to take a look at the knowledge systems that people build up around seasonality, and how these knowledge systems can reflect long-term change.
For me, this means lots of interviews with mountain villagers about rhododendrons and climate change. Although my Naxi has improved to the level of a few terms — all botanical — I've become a firm believer in working with Naxi and Yi interpreters.
The interpreters are usually young men and women who speak great English and Chinese. In general they're as interested in the ethnobotanical knowledge of the older villagers as I am. That is why we hope to make some of that knowledge more widely available with a Naxi ethnobotanical audio dictionary that we hope to put online next year.
GK: When Joseph Rock worked for the National Geographic Society he traveled in style and kept requesting larger and larger grants for his research. Are there any similarities between your field work and his?
Hart: I've read that Rock traveled with a collapsible bathtub. Sometimes when I'm up on the mountain for a long time, that sounds quite nice. But, in fact, I'm able to take advantage of the field station and do most of my work light and fast.
I work alone or with my wife, and working mostly in day trips. This is one of the great things about the natural-history type of ecology I'm doing – the biggest budget item is replacing worn out boots!
Editor's note: Robbie Hart would like to express his thanks to the National Science Foundation, the Whitney Harris World Ecology Center, and the Explorer's Club, which have all provided grants and material assistance for his research. He would also like to thank the staff at the Lijiang Alpine Botanic Garden and the interdisciplinary ecologists, geographers, political scientists, anthropologists, and public health scholars working in northwest Yunnan.
Rhododendron adenogynum image: Dr Jan Salick
All other images: Robbie Hart