Increased human activity
The Qinghai-Tibet Highway and Railway, which crosses Hoh Xil, connect the nature reserve to the outside world.
However, according to the IUCN's assessment, the two roads, while bringing convenience to locals, are among the biggest threats to local wildlife. "The busy Qinghai-Tibet Highway severely affects the migration route of the Tibetan antelope from the Sanjiangyuan Nature Reserve to their calving grounds and back, as well as the movement of wildlife in general …," according to the report.
The report advises the nature reserve to block traffic for up to two hours per day during the migration period at passing points to let the animals cross the highway.
Fences, set up for husbandry and anti-desertification purposes, are also a notable threat as they disrupt the migration route of Tibetan antelopes, according to the report.
For volunteers like Cairen, however, what is most alarming is the increasing amount of garbage that has piled up in the area as a result of the increased human activity along the highway and railway.
On the afternoon of July 13, Cairen and his fellow volunteers collected 67 large storage bags of garbage within 100 meters on the Qinghai-Tibet Highway. The biggest bag was stuffed with over 200 food packages, cans and plastic beverage bottles.
Some of that garbage can be swept into Hoh Xil's grassland. Two years ago, a herder found that one of his goats had died after choking on a plastic package of a popular snack.
"The goat likes the smell of oil on the package. As it licked the package, it accidentally swallowed it. Most of these packages are thrown here by tourists and drivers of long-distance trucks," Yang said.
The garbage doesn't just come from the tourists; locals also contribute to it. Cairen recalls that when he was young, villagers would dispose of their garbage right outside their village. Goats would search for food in the piles of garbage as high as two meters and spread over a stretch of 1 kilometer.
Each year, during the annual horse racing, herders would gather together, light up fire and cook in the open, celebrating the occasion with strong-flavored snacks and food. After the race was over, the crowd would disperse, but iron, glass and plastic containers and utensils would be left behind in the plateau, attracting curious animals who passed by.
Cairen started to collect garbage as a volunteer when he was in primary school.
In 2001, Yang organized a volunteer garbage-picking team in Tanggula Mountains Central Primary School. As a member of the first batch of volunteers, Cairen and 12 fellow members, wearing badges and holding flags, started to pick up garbage initially in their school and then in the town. Grown-ups, afraid of being "taught" by the kids, often collected their garbage when they saw the team coming.
Over the years, the volunteer team expanded from young students to adults and even celebrities. The garbage collection program also upgraded into an exchange program in which people could swap waste materials for food: 10 plastic water bottles, for example, could be exchanged for a new bottle of water; 10 instant noodle containers for a box of instant noodles; and 10 used batteries for four new ones.
Rising temperature
The rising temperature also poses a threat to the ecology of Hoh Xil.
Tudan Danba, a local herder, said he feels that winters have become warmer in recent years. In the past, herders would start slaughtering cows and goats in October to prepare for the chilly winter. Now, the time for the slaughter has been pushed back to late November because if they slaughtered the animals earlier, the meat will go bad quickly.
According to IUCN's report, from 1961 to 2014, the annual average temperature change in Hoh Xil was 0.34 C per decade. The recorded average annual precipitation increased by 20.7 millimeters per decade, the Xinhua News Agency reported, quoting Qinghai Province meteorological data.
Wen, the Peking University researcher, is also shocked by the rapid climate change which has resulted in a change in geographical features. "The speed of change is rapid, with striking effects," he said.
From 2005, Green River, together with glacier experts from the Chinese Academy of Sciences, started to monitor and study the source of the Yangtze River.
By comparing and analyzing aerial shots and satellite pictures of different periods, they found that the largest melting range of the Gangjiaquba glacier, the biggest glacier at the source of the Yangtze River, expanded to over four kilometers from 1969 to 2007.
The melting of snow and the rise in precipitation have increased the water volume of the river body and turned some rangeland into lakes and wetland. While this has increased biodiversity in the region, Wen is also worried that this could affect the habitat of ungulates. "The habitats for Tibetan antelopes and yaks in the summer could shrink," he said.
But he also admits that these issues haven't yet been systematically studied. Following Hoh Xil's designation as a UNESCO World Heritage site, the effect of global climate change on the area's water environment will be studied through long-term monitoring.
