"Watch out for the reed thorns, they can prick your hands!" Xie Yonghong cautioned the students as he held up a reed stalk towering over half a meter taller than them.
"You need to dig out a soil sample first, determine the range of soil extraction, and then take samples according to the required size. Make sure to preserve the samples properly." Under Xie Yonghong's guidance, the students divided tasks such as digging soil, positioning, sampling, taking photos, etc.
Xie Yonghong (second from right) and team members conducting sampling. Photo by Wang Haohao.
The sampling location they visited was the Dongting Lake large plot monitoring point at the Dongting Lake Wetland Ecological System Observation and Research Station of the Chinese Academy of Sciences (referred to as the Dongting Lake Station), which is as large as 300 football fields.
In 2009, the Dongting Lake Station was established by the Subtropical Agroecology Institute of the Chinese Academy of Sciences (referred to as the Subtropical Institute). This is one of the long-term observation and research bases for lake wetland ecosystems in the middle and lower reaches of the Yangtze River established by the Chinese Academy of Sciences. Xie Yonghong is the deputy director of the Subtropical Institute and the director of the Dongting Lake Station.
"Dongting Sparrow" is the WeChat nickname specifically chosen by Xie Yonghong. Sparrows are migratory birds and not regular visitors to Dongting Lake. He hopes that this special group of "Dongting Sparrows" will guard the clear waters of Dongting Lake and attract and retain more migratory birds through research on wetland ecosystems and biodiversity restoration.
More than ten years have passed, what changes have occurred in the Dongting Lake wetland ecosystem and biodiversity? During the Spring Festival, reporters from the "Chinese Science Bulletin" followed the footsteps of the "Dongting Sparrows" for two days to find the answer.
Reed beds on Dongting Lake. Photo by Wang Haohao.
Exploring the "home ground" of Dongting Lake with footsteps
In the winter, Dongting Lake is vast and misty, with water and sky merging into one. The withered yellow reeds sway in the wind, while various migratory birds on the lake either forage or soar swiftly, creating a harmonious ecological picture of humans and birds.
Winter at Dongting Lake, migratory birds soar. Captured by Zou Ye.
"Look at those stretches of sandbars over there, each row of white dots represents swans. During this season, thousands of swans inhabit Dongting Lake; the highest numbers of migratory birds include bean geese, small white-fronted geese, and pochard ducks, among others. Those gray-brown ones are bean geese," said Xie Yonghong enthusiastically, standing dozens of meters away from the sandbars on the embankment of Dongting Lake, continually sharing insights with the journalist. "This is the scene that wetland researchers at Dongting Lake most want to see."
Subsequently, he led the journalist into the scientific monitoring point of the lake area, observing the new changes in the wetland. "We know everything about which water grasses are in this area and which areas the migratory birds prefer to stay in."
Fortunately, with every stop, Xie Yonghong made new discoveries: there are increasingly more insect eggs in the soil of a stretch of sandbars by the lake; water grasses previously unseen in the lake area have appeared; and migratory birds have visited areas they previously ignored, as indicated by the bird droppings on the sandbars...
Soil Bug Eggs. Photo by Wang Haohao.
"The decisive factor for whether migratory birds come or not is not just about the birds themselves, but more importantly, it's about what's on the ground, what's in the lake. That's the key to their habitat. Only when the water quality improves, when there are more water plants and abundant underwater life, can migratory birds survive here," said Xie Yonghong, looking as excited as a farmer seeing a bountiful harvest.
Seeing this picturesque ecological beauty, Xie Yonghong recalled the first time he saw Dongting Lake.
Dongting Lake, located in the northeast of Hunan Province, is the second largest freshwater lake in the Yangtze River basin in China. It is also one of the only two remaining natural through-flow lakes in China, known as the "kidney of the Yangtze River."
It was the end of 2006 when Xie Yonghong's colleagues from the subtropical eco-research institute took him to Dongting Lake for research. Although he is from Chenzhou, Hunan, he had never been to Dongting Lake before, "Back then, my family was poor and couldn't afford to travel."
After conducting research around the eight-hundred-li Dongting Lake, Xie Yonghong spent about five days, "Back then, there were no asphalt roads like now, just dirt roads full of bumps and pits. Every time we traveled, the tires would burst at least once; after the dirt roads, we had to take a boat, and when the boat couldn't go any further, we had to walk."
In the subtropical ecology institute, Xie Yonghong showcases the aquatic plants he keeps in his office.
Reflecting on his journey, Xie Yonghong was struck not by the difficulties along the way, but by what he saw and heard, marveling at how "Dongting Lake was basically the battleground for economic development back then."
"The entire lake area was all about making money," Xie Yonghong exemplified, mentioning how sand excavation was profitable with minimal costs, and fishing was lucrative with approximately 50,000 licensed fishermen in the area at the time. People were farming snails, raising shrimp in enclosures, growing rapeseed, planting poplar trees, and there were even iron foundries and plastic factories in some villages, severely polluting the ecological environment of Dongting Lake.
"The main ecosystem services of Dongting Lake are flood regulation and biodiversity conservation. But what I saw back then was complete destruction," Xie Yonghong remarked, firming his resolve to study the wetlands of Dongting Lake.
Today, the research focus of the Dongting Lake station includes long-term monitoring of wetland ecosystems, landscape patterns in the basin and ecological responses of lakes, wetland ecosystem evolution and restoration, biodiversity conservation and enhancement of functions, as well as wetland resource utilization and ecological agriculture.
Overlooking Dongting Lake Station. Photo by Zou Yelove.
Xie Yonghong said that in the past, everyone talked about the importance of Dongting Lake, but no one presented relevant original research data. Instead, they wrote opinion articles, citing articles based on hydrological data, with very little environmental monitoring.
Dongting Lake Scenery. Photo by Wang Haohao
Since 2009, Xie Yonghong has led a team to thoroughly understand the ins and outs of Dongting Lake over a period of more than five years. During these five years, without any project funding, the team managed to gather a large amount of first-hand data. "We conducted comprehensive surveys on the main vegetation, community types, and species situation of Dongting Lake, providing accurate data support for targeted research on ecological restoration of the lake," said Xie Yonghong.
A Group of Non-Migratory Birds at Dongting Lake
"Shh, let's walk slower and not disturb the migratory birds ahead," said Xie Yonghong as we approached a sampling site at Dongting Lake. Suddenly, he slowed down, crouched down, and his colleague, Dr. Zou Ye'ai, an associate researcher at the Subtropical Institute of Ecology, took out equipment to observe the flock of migratory birds in the distance. They were foraging next to a low levee about a dozen meters away.
Xie Yonghong (right 2) and other team members are sampling in the reeds. Photo by Wang Haohao.
Xiaosai Lake is located in the heart of Dongting Lake, with a total original area of 27,800 mu, spanning three counties and cities: Yuanjiang, Xiangyin, and Miluo. In 2001, Xiaosai Lake was contracted out to individuals who built embankments and enclosed the area to plant trees and raise fish. The Hunan Provincial Party Committee and Government have repeatedly ordered rectification. In May 2018, the Ministry of Ecology and Environment dispatched an inspection team to conduct a special inspection on this issue and later demolished all the embankments and regulating gates.
"Illegally enclosing lakes is indeed despicable, but through long-term monitoring, we have found that some naturally formed enclosures are beneficial for migratory birds to roost. After dismantling the enclosures, migratory birds no longer come to the core area of Dongting Lake but instead go to some small lakes outside Dongting Lake to roost," said Xie Yonghong. He and his team will turn their research results into recommendations, actively communicate with government departments, and hope to preserve some of the embankments.
After multiple surveys by relevant government departments, it was recognized that some embankments indeed need to be preserved. In the end, 14 embankments in the Dingtzi Dam and Xiaoxihu in the core area of East Dongting Lake were preserved. These embankments are now one of the most concentrated areas for migratory birds to roost in Dongting Lake.
Populus nigra, once popular in the Dongting Lake area, but its large-scale planting has damaged the natural ecology of Dongting Lake. In November 2017, the Hunan Provincial Party Committee and Government issued a mobilization order to fight for the ecological environment of Dongting Lake and start a new journey of ecological civilization construction, requiring all poplar trees in the core area of the Dongting Lake Nature Reserve to be cleared by December 31.
Why cut down poplar trees? What exactly is the harm of poplar trees to wetland ecology? Xie Yonghong's team provides answers with research results.
He cited examples, saying that the team found through research that under poplar trees, the proportion of xerophytic plants is much higher than that of hygrophytic plants, which is not conducive to wetland protection. Many herbaceous plants will gradually transform into woody vines or shrubs, causing changes in plant types, ultimately leading to surface dryness and groundwater decline, "Poplar trees act like pumps, draining away water."
Based on this, the team conducted a systematic study on the water migration mechanism of Dongting Lake wetlands and pioneered the study of vegetation belts in Dongting Lake, discovering the migration rate of vegetation belts in the Dongting Lake area, and transforming the qualitative research on the downward movement of Dongting Lake vegetation belts into quantitative research.
The team led by Xie Yonghong is conducting sampling activities at Dongting Lake. Photo by Wang Haohao.
During the interview, Xie Yonghong frequently used the term "Dongting sparrows" to describe himself and his colleagues who have been studying Dongting Lake for over a decade. Sparrows are resident birds, not migratory birds that frequent the habitat of Dongting Lake. So why are they called "Dongting sparrows"?
He shared a story with the reporter that is popular in places like Yueyang. Although it may sound a bit folkloric, to the locals, "Dongting sparrows" is a term of praise, indicating someone with rich experience, and many people like to use it as their online pseudonym. With Dongting Lake stretching over eight hundred li, young sparrows cannot fly across it. However, the older sparrows will pick up a twig and, when unable to fly, use it to rest on the water's surface.
"Everyone is called an old sparrow, but I still feel young, so I dropped the 'old' from the name," Xie Yonghong said. He chose this name with the hope of building a research team focused on Dongting Lake wetlands. Through the mentorship of the "old sparrows," he aims to encourage more young people to become "resident birds" at Dongting Lake and continue ecological research on wetlands.
Currently, Xie Yonghong has mentored over 30 master's and doctoral students, and there is now a dedicated research team at Dongting Lake Station. They have established multiple research platforms, including the Datong Lake Agricultural Green Transformation and Development Research Base.
The reeds sway in the wind. Photo by Wang Haohao.
The team of "Dongting Sparrows" has continuously produced batches of scientific research results. Their advisory suggestions on Dongting Lake wetland restoration, water quality improvement, and national park construction have been adopted by superior departments several times.
"In recent years, on one hand, we have been carrying out ecological protection and restoration work in Dongting Lake. On the other hand, we have established the Datong Lake research base for water environment governance. The technology of the four ponds and two dams system has also been comprehensively promoted in Hunan Province. In the future, we will continue to exert efforts in scientific research, contributing the scientific research strength that the Chinese Academy of Sciences should have to safeguard the clear waters of Dongting Lake," said Xie Yonghong.
