Climate warming undermines the benefits of grazing removal for alpine plant population maintenance on the Tibetan Plateau

A central question in restoring degraded grasslands is whether grazing removal can sustain viable plant populations under both current and future warming conditions. Addressing this question requires demographic studies integrating vital rates responses to grazing removal and climate warming throughout a species life cycle. However, studies of this nature are rare. Using stochastic Integral Projection Models parameterized with four years (2020-2023) of demographic data, we find that nine years of grazing removal increases the stochastic population growth rate (log{lambda}S) of two coexisting herbaceous plants, Carex atrofusca and Sibirotrisetum sibiricum at two altitudes (3,700 m and 4,000 m) in an alpine grassland on the Tibetan Plateau. Although individual survival declines following grazing removal, these negative effects are overcompensated by enhanced plant growth, ultimately promoting log{lambda}S in both species. However, the benefits of grazing removal are cancelled under nine years of in situ active warming (+2{square}), where no demographic compensation occurred (i.e., vital rates change in the opposite directions among populations), and log{lambda}S are even lower than those under grazing. Our findings suggest that while grazing removal is a sustainable management strategy under current climate conditions, it may not remain effective under projected warming, providing valuable information for sustainable population management under global change.