Informal Trust, Formal Collective Participation, and Herders’ Willingness to Share Grassland Commons on the Qinghai–Tibet Plateau

Following China’s Household Responsibility System, grassland commons-sharing has been proposed as a pathway toward sustainable rangeland management, but the drivers of herders’ cooperation remain unclear. Using village-clustered survey data from 375 herder households in Zoige County on the Qinghai–Tibet Plateau, this study applies Probit models to examine how informal trust, formal participation, ecological perception, and anticipated migration relate to willingness to share grassland. Formal participation is significantly negatively associated with willingness (−5.9%), consistent with, though not sufficient to establish, motivational crowding-out; trust in fellow villagers is positive but only marginally significant (+6.9%, p ≈ 0.05), while informal interaction is not robustly associated with willingness. Ecological perception shows a directional divergence: greater perceived degradation and shorter grass on a household’s own pasture raise willingness, while declining regional rainfall lowers it. Anticipated migration shows a robust positive association (+15.1%, p < 0.05), consistent with an exit-driven mechanism. Among already-unwilling households, dense neighborly ties are associated with entrenched refusal. Only 34.1% of households operate non-independently, versus 43% expressing willingness, indicating stated willingness and realized practice are distinct. For governance actors, findings suggest evaluating and improving the design of formal collective activities, their voluntariness, transparency, and perceived usefulness, alongside building exit-friendly institutions, while cultivating trust networks should be treated more tentatively.