Premise of the Study: With biodiversity and rates of climate change among the highest, the eastern Himalaya are critical for understanding the interaction of these two variables. However, there is a dearth of longitudinal data sets that address the effects of climate change on the exceptional alpine biodiversity of the Himalaya.
Methods: We established permanent alpine vegetation monitoring plots in three mountain chains of the Hengduan Mountains, the easternmost Himalaya, which have warmed 0.03-0.05°C yr⁻¹ since 1985. Recently, we resampled plots (176 1-m² quadrat plots and 88 sections of 11 summits in three Hengduan mountain chains) to measure changes in vegetation after 7 years.
Key Results: Over 7 years, Tibetan alpine vegetation increased in number of species (+8 species/summit; +2.3 species/m²), in frequency (+47.8 plants/m²), and in diversity (+1.6 effective species/m²). Stepwise regressions indicated that warmer temperatures, southerly aspects, and higher elevations were associated with greater increases in these vegetation metrics. Unexpectedly, Himalayan endemic species increased (+1.4 species/m²; +8.5 plants/m²), especially on higher-elevation summits. In contrast, the increase in relative abundance of non-alpine species was greater at lower-elevation summits. Plants used by local Tibetans also increased (+1.3 species/m²; +32 plants/m²).
Conclusions: As in other alpine areas, biodiversity is increasing with climate change in the Himalaya. Unlike other areas, endemic species are proliferating at the highest summits and are indicators of change.