Temporal and spatial changes of ungulate activity before and after the construction of the Qinghai-Tibet railway in Hoh Xil, China

The construction of the Qinghai-Tibet railway (QTR) parallel to the Qinghai-Tibet highway (QTH) has been associated with concerns about its impact on local wildlife. However, to date, most related research has been conducted after the QTR was built, and there is a lack of evidence of the effect of its construction on wildlife. By comparing ungulate survey data along the QTH between 2001 and 2020, an increase in the migration number of Tibetan antelope in the region from around 2000 to 4000 was observed, despite a rise in traffic on the highway from approximately 1000 to 2000 vehicles per day. The average number of kiangs in each survey along the QTH increased from 18 to 32, and the average number of Tibetan gazelle increased from 14 to 16. The herd sizes of Tibetan antelope, Tibetan gazelle, and kiangs during the construction of the QTR were significantly larger than those after the construction of the QTR. After the construction of the QTR, the number of ungulates along the QTH was negatively correlated with the traffic volume, but positively correlated with the distance between the QTH and the QTR. By comparing the distributions of ungulates before and after QTR construction, it was also found that the number of ungulates decreased in areas where the QTH and QTR were close, but increased where the QTH and QTR were further apart. This suggests that the close proximity of the two linear infrastructures can have a cumulative negative effect on ungulate numbers. These findings provide a reference for the future construction and planning of linear infrastructures on the Qinghai-Tibetan Plateau.