Ancient engineers: The role of plateau pika in shaping ecological uniqueness and guiding plant diversity conservation in alpine grasslands.

Small burrowing herbivores play a crucial role in maintaining structure and function of grassland ecosystems. To date, our understanding of whether practicing ecological uniqueness can enhance plant diversity conservation under small herbivore disturbances remains limited. Here, we investigate the ecological uniqueness of plant communities, which include habitats disturbed and undisturbed by plateau pikas. In 30 geographic regions of alpine grasslands, plateau pikas lead to plant assemblages that differ from those in undisturbed habitats and reduce the ecological uniqueness. During this process, plant turnover dominate the changes in ecological uniqueness. In the presence of plateau pika, the influence of altitude is diminished, with plant relative abundance, species richness, and functional richness measurements emerging as core predictors of ecological uniqueness. Notably, the negative effect of relative abundance on ecological uniqueness shifts to a positive effect, supporting the status of the plateau pika as ecosystem engineers at larger spatial scales. A combined beta regression model incorporating bare patch areas and active burrow entrances explains 46% of the variation in the ecological uniqueness. Given the limited resources available for conservation, we propose prioritizing the protection of undisturbed and low-intensity plateau pika habitats, rather than pursuing eradication. Additionally, near-natural restoration (e.g., controlling pika populations, sustainable grazing) in highly disturbed habitats is crucial for maintaining ecological uniqueness. This study provides new insights into the roles of small burrowing herbivores at the regional scale, which can guide grassland conservation efforts.