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This photo taken on March 26, 2025 shows a view of the Nujiang River canyon in Lisu Autonomous Prefecture of Nujiang, southwest China's Yunnan Province. [Photo/Xinhua]
Li Yuhua, a 38-year-old woman of the Dulong ethnic group, lives beside the emerald-green Dulong River in China's remote southwest. The towering Gaoligong Mountains, draped in dense forests, are also located in this region and are home to rare plants and animals.
Li's hometown has a long name -- Dizhengdang Village, Dulongjiang Township, Gongshan Dulong and Nu Autonomous County, Nujiang Lisu Autonomous Prefecture, Yunnan Province, southwest China.
Notably, in Li's childhood memories, the mountains here were not this lush. Back then, villagers would slash and burn patches of mountainside to plant corn and potatoes, moving to a new patch the following year.
"This farming method not only harmed the forests but also didn't yield enough food to fill our stomachs. To survive, we had to forage for wild greens in the mountains and fish in the river," she recalled.
"Rainbow" forest ranger
Since China implemented the policy of returning farmland to forests over the past two decades, local farming and lifestyle patterns have undergone changes -- and the mountains have gradually turned greener.
In 2016, the local government established forest ranger positions. With her husband working away from home, Li applied for this job, earning an extra income of 800 yuan (about 111 U.S. dollars) each month.
As one of the few female rangers, Li trained hard to build her physical strength, learned rock-climbing techniques and gained fire prevention knowledge.
She and her team patrol the rugged mountains year-round, guarding 1,600 square kilometers of forest. The treacherous mountain paths are tough on her shoes, with Li wearing out over a dozen pairs each year.
Featuring deep valleys, steep ravines and slippery ground when it rains, patrol work is a daunting task in this area. When encountering impassable torrents without access to bridges, she has to tie ropes to zip-lines and glide over the rushing water.
"When we meet people in the mountains, we remind them -- no flames, no smoking and no digging up wild herbs. Some locals don't understand, saying this is everyone's home, and so why can't we dig? We patiently explain that precisely because it's our shared home -- we must all protect it together," she said.
"This forest is our lifeline. Now, the trees grow denser, the river water clearer, poaching and illegal logging have vanished, and wild animals are increasing," Li said.
While patrolling, Li loves wearing the unique, vibrantly striped clothing of the Dulong ethnic group, resembling a rainbow. The villagers call her the "rainbow ranger."
Vertical mountain kingdom
The Gaoligong Mountains protected by Li and her colleagues serve as the core area of the "Three Parallel Rivers" World Heritage site in Yunnan Province.
Stretching over 600 kilometers north to south, the highest peak pierces the clouds at 5,128 meters, while the lowest valley sits at 645 meters. This nearly 4,000-meter elevation drop creates a rare marvel -- the vertical distribution of tropical, subtropical, temperate and cold temperate forest ecosystems in the same mountain range.
Niu Yang, deputy director of the Kunming Institute of Botany (KIB) of the Chinese Academy of Sciences (CAS), explained that under the influence of warm, moist air currents from the Indian Ocean's Bay of Bengal, the Gaoligong Mountains region has developed unique climatic characteristics and exceptionally rich biodiversity.
Though the Gaoligong Mountains cover only 0.36 percent of China's land area, they shelter approximately 17 percent of China's higher plant species and 26 percent of its vertebrate species. This region is home to about 29 percent of China's mammal species and roughly 54 percent of China's bird species -- making it the "kingdom" with the richest mammalian and avian diversity within any single natural geographic unit in China.
The mountain area here harbors not only many of China's unique rare and endangered wildlife but also serves as the sole habitat and refuge for certain global species. Its unique geography and climate also make the Gaoligong Mountains a vital "life corridor" for migratory birds. In addition, it contains the world's largest and best-preserved expanse of mid-mountain humid evergreen broad-leaved forest, according to Niu.
Researchers from the Germplasm Bank of Wild Species at the KIB have ventured deep into the northern Gaoligong Mountains to conduct an investigation of wild plant germplasm resources. They trekked 420 kilometers into uninhabited areas.
Using drones and rope techniques, the researchers successfully collected precious seeds from a 1,000-year-old Taiwan Cypress standing 72 meters tall, a first-time achievement. They also discovered four new species and two species newly recorded in China.
"We have strengthened scientific research and monitoring in the Gaoligong Mountains, and deepened cooperation with the CAS and other research institutions -- concerning important species, extremely small population species, and rare and endangered species, and are fully committed to protecting this green treasure trove," said Zhang Ying'an, director of the Nujiang Management Bureau of the Gaoligong Mountain National Nature Reserve.
Lab in nature
Li Yingchun, a Dulong ethnic researcher born deep in the mountains, used to walk five days to reach his middle school. However, his deep love for his homeland led him to return to work at the Gaoligong Mountain National Nature Reserve after graduate school. Then he dedicated himself to building a forest ecosystem field observation and research station in the Gaoligong Mountains.
Li and his colleagues conduct long-term fixed-position observations of water, soil, air and biology within the primeval forest -- at an altitude of over 2,200 meters.
Leeches are very common in this area when it rains, ticks are rampant in sunny weather, and snakes are frequent visitors.
However, these annoyances and dangers have not succeeded in deterring the researchers. After every heavy bout of rain, Li climbs steep slopes to meticulously measure changes in surface and underground water within the observation plots.
Sun Jun, deputy director of the station, explained that since its establishment in 2022, the station has focused on monitoring the forest ecosystems of the Gaoligong Mountains.
Through long-term field observations and the accumulation and integration of massive datasets, the researchers aim to elucidate the structure, function and evolution of ecosystems, reveal their responses to global climate change, explore mechanisms of ecosystem degradation and restoration, and develop technologies and demonstration models for restoring degraded ecosystems.
Li Rong, executive director of the research station, highlighted the site's unique value: "Most areas at this latitude on Earth lack vegetation cover, yet only this region in China remains lush and green. The warm, moist air currents from the Bay of Bengal are blocked by the Gaoligong Mountains, transforming into abundant rainfall. Observation data show that the average annual rainfall here exceeds 3,000 millimeters -- making it one of the wettest areas in China."
"This area plays a pivotal role in biodiversity and the structure and function of ecosystems. Conducting monitoring and research here holds extraordinary significance for protecting biodiversity and understanding global ecosystems," Li Rong said.
He noted that the unique mid-mountain humid evergreen broad-leaved forest, thriving at elevations between 1,800 and 2,600 meters in the Gaoligong Mountains, is crucial for the structure and functioning of the other ecosystems in this mountain range. Some of the tallest trees on Earth grow in this region. Research indicates that only under specific precipitation and temperature conditions can trees attain such great height. This forest also plays a vital role in soil and water conservation.
Looking ahead, Li Rong said: "We hope to cooperate with scientists worldwide to conduct research at the station to jointly explore major scientific questions such as ecosystem structure and function, extreme climate events, carbon peak and carbon neutrality, allowing this 'natural laboratory' to benefit the world."
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