Foundational cushion plants sustain a prominent proportion of alpine
biodiversity, but they are quite sensitive to climate warming hence
their population dynamics have important implications for biodiversity.
The potential biodiversity changes with the population dynamics of
cushion plants in alpine ecosystems remain, however, unclear. Using
eight communities along a climatic and community successional gradient,
we assessed ecological drivers of population dynamics and associated
plant diversity changes in alpine communities dominated by the
foundational cushion plant Arenaria polytrichoides. The population
degeneration of Arenaria is attributed to ecological constraints,
including temperature, water and light availability, extreme climate
events, and interspecific competition, at a series of life history
stages. Once Arenaria populations completely degenerate, previously
cushion-dominated communities shift to climax communities that are
overwhelmingly dominated by sedges. Future degeneration of foundational
cushion populations induced by climate warming will therefore induce a
biodiversity collapse in alpine ecosystems.