Rapid changes in eastern Himalayan alpine flora with climate change

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.

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.

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 ).

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.