XJTLU researchers uncover link between pikas and plateau soil erosion
18 Jul 2025
The alpine meadows of China’s western Qinghai-Tibet Plateau offer far more than meets the eye. They are vital stopovers for migrating Tibetan antelopes, grazing pastures for yaks, and a “carpet of life” for millions of nomadic herders who have survived here for generations.
However, this vast landscape faces an ecological crisis, with nearly 70% of its grasslands experiencing degradation.
A research team from Xi’an Jiaotong-Liverpool University recently completed a project that shed fresh light on the feedback mechanisms between disturbances caused by herbivores, such as yaks and pikas, and the formation of black soil patches on the plateau.
Building on earlier studies, the team used an interdisciplinary approach – combining geography, ecology, animal behaviour, and computer science – to develop a cellular automata model to simulate the degradation process, providing a scientific foundation for early warning and ecological restoration strategies.
“Grassland degradation is essentially a positive feedback process. Once bare patches begin to form, it’s important to watch for signs of a vicious cycle,” says Dr Li Li, an assistant professor in XJTLU’s School of Science, who led the project.
During a field trip to the 4,000-metre-high Nyenpo Yurtse region of Qinghai Province, her team discovered a divergence in views on the causes of this degradation: local authorities attribute the problem to overgrazing and the booming pika population, yet scholars are debating the interplay between climate change and human activity.
Dr Li Li (second right) with PhD students (from left) Dan Li, Zi’ao Liu, and Huxuan Dai
Dr Li says research has shown that excessive grazing and trampling by livestock create bare patches, which in turn attracts pikas, whose ideal habitats are environments where grass is mixed with exposed soil, with sparse, low vegetation.
“As their diet overlaps significantly with the yaks, a rising pika population reduces the availability of forage,” she explains. “This shortage pushes yak herds to congregate on the remaining healthy meadows, which accelerates the formation of new bare patches.”
As such, the presence of pikas is a symptom of the degradation, not the root cause.
“At the same time, climate change is bringing more extreme rainfall events to the eastern plateau,” says Dr Li. “This causes surface soil on slopes to be washed away repeatedly, slowing down vegetation recovery and further worsening the ecological condition of the grasslands.”
Researchers attach trackers to pikas and yaks
Prime pastures
In the Nyenpo Yurtse region, XJTLU PhD student Dan Li was tasked with placing acceleration and GPS sensors onto the horns of yaks, while her colleagues caught pikas as they darted in and out of their burrows to fit tracking devices.
Drones hummed overhead as they swept the meadow, capturing remote-sensing imagery. Together with data gathered from the ground, these images were fed into the cellular automata model to build a dynamic ecological map.
Using pasture data from 2014 and 2023 as anchor points, the team validated the model’s ability to precisely capture the positive feedback processes. With these efforts, researchers aim to simulate the evolution of individual grassland patches under the combined influences of grazing, pika activity, and other ecological factors.
“We’re delving deeper into the algorithms behind the cellular automata model,” says Dr Li. “We hope to generate simulations that clearly show how grasslands evolve under different grazing intensities. This way, herders will be able to intuitively understand the changing trends of their pastures, thus managing and protecting their grasslands more effectively.”
Grassland degradation simulation using a cellular automata model including (a) 2014 RGB imagery, (b) 2014 bare soil distribution map, (c) 2023 bare soil distribution based on UAV imagery, and (d) 2023 simulated bare soil distribution generated by the cellular automata model
Herders use homemade tools to compact the ground after seeding. Credit: Zhaqiongcang
Tools of change
In 2017, a visiting herder from Switzerland advised the community in Nyenpo Yurtse to plant grass, but in keeping with nomadic tradition – and a deep-rooted scepticism to anything new – the locals rejected the idea.
However, two years later, they had had a change of heart, and community leaders unexpectedly contacted Dr Li to ask about planting grass. Where grassland degradation was once seen as “heaven’s will”, researchers have helped villagers understand the ecological mechanisms behind these changes.
To enhance the effectiveness of grassland restoration, Li has also teamed up with industrial designers, leaders of grass planting initiatives, the director of a county grassland station, and the head of the Qinghai Grassland Conservation Centre to co-design tools for pasture restoration.
“Next month, we’ll field test the 3D-printed prototype tools on the plateau,” she says. “Vincente Estaban, our colleague in XJLTU’s Industrial Design Department, even came up with the idea of a ‘scripture-chanting seeding machine’. Each turn not only sows seeds but also offers a Buddhist blessing, turning the act of planting grass into a virtuous deed.”
Staff at the Design School discuss the tools with the team
In addition, Dr Li has been exchanging ideas with anthropologists, ecological artists, Buddhist monks, and experts in many other disciplines, to get their perspectives on protecting the meadows and the environment at large.
“These interdisciplinary and transdisciplinary dialogues have greatly broadened my understanding of the issues,” she says. “Ecology might advise reducing livestock numbers, while sociology reminds us that cattle and sheep are central to the livelihoods and cultural identity of herders.”
The researchers with members of the nomadic community
Despite the difficulty of the task ahead, Dr Li remains optimistic. “We’ve faced countless challenges, but we’ve always believed we could overcome them, because we’re working on real issues that truly matter to local communities,” she says. “I believe we’ll find solutions and that these grasslands will thrive once again.”
This project received support from the National Natural Science Foundation of China’s Young Scientists Fund.
By Research Management Office
Translated by Xiangyin Han
Edited by staff editor and Catherine Diamond
Images courtesy of Dr Li Li
18 Jul 2025