Objectives  To explore the response degree of spatial distribution of grassland biohazard to terrain factors in the Yili River Valley, and provide theoretical support for grassland biohazard prevention and control and grassland healthy development.

  Methods  Based on field investigation and geographic information technology, the spatial distributions of rodent, pest, and poisonous grass damage in Yili Valley grassland were analyzed from the perspective of terrain, and the driving mechanism of terrain to grassland biohazard was analyzed based on the geographic detector.

  Results  1) In the Yili Valley, grassland rodent infestation occurred in a large area between 900−1 200 m and 1 600−2 100 m above sea level. The pest infestation was mainly concentrated in the area between 800−1 900 m above sea level. The regularity of poison and grass infestation was obvious in vertical space, mainly concentrated in the area between 1 800−2 500 m above sea level. After reaching the peak at the altitude of 2 000−2 100 m, the area began to decrease, and almost no poison and grass damage occurred at the higher and lower levels. In slope space, grassland biohazards mainly focused on gentle slopes with gradients ranging from 6° to 15°. Most of the biohazards occurred in the spaces with small gradients such as flat slopes, gentle slopes, and slopes, and a small part of biohazards occur on steep slopes. Grassland biohazards occurred in all slope directions, and the difference of disaster areas in different slope directions was not obvious. 2) Slope had significant effects on rodent and insect pests, while slope aspect had no significant effects on the three biological hazards. 3) Grassland biohazard was affected by multiple topographic factors, and the interaction between elevation and slope was significant, while the interaction between elevation and slope aspect was not significant. 4) There were significant differences in the effects of elevation and slope, slope direction, and slopeslope direction on the distribution of rodent damage and poison weed damage in grassland. There was no significant difference between elevation and slope on pest distribution in grassland. Biohazards in the Yili River Valley grassland were significantly affected by topography, and different types of biohazards had different response degrees to topography. The interaction between elevation and slope showed a nonlinear enhancement effect on the distribution of biohazards in the grassland.

  Conclusions  The research on the topographic driving mechanism of biohazard in Yili Valley grassland could provide scientific guidance and a theoretical basis for the formulation and implementation of a grassland protection plan in Yili Valley in the future.