The study looked at how plant diversity and aboveground biomass change with altitude in an alpine meadow in the Three-River source region. They found that higher altitudes had different types of grasslands with more diverse plant species and biomass. The distribution of species diversity and biomass followed a peak pattern at mid-altitude locations. The trends in species diversity, richness, and biomass also showed a peak pattern, with the highest species diversity occurring at moderate productivity levels. This research provides valuable insights for conserving grassland biodiversity and maintaining ecosystem functions in the Three-River source region.