Assessment of climate change effects on alpine summit vegetation in the transition of tropical to subtropical humid climate
2021
Kuo, Chu-Chia | Su, Yu | Liu, Ho-Yih | Lin, Cheng-Tao
Mountain ecosystems are globally among the most vulnerable to the impacts of global warming. This study is carried out on high-mountain summits dominated by dwarf bamboo, Yushania niitakayamensis, in the alpine zone of subtropical Taiwan. A total of six summits were selected using a multi-summit approach, following the common protocol of the Global Observation Research Initiative in Alpine Environments (GLORIA). To assess the climate change effects, we used the soil temperature and statistical downscaling precipitation data to analyze the climatic changing patterns, also applied enhanced vegetation index (EVI) and vegetation diversity index to assess the vegetation responses among summits along the timeline. The results showed that the temperature has a significant increase in all summits, especially in winter. The annual chilling days have reduced around 50% from 2010 to 2019, which would imply the extension of plant growing season. The EVI values showed a tendency to increase over time. Furthermore, the long-term trend of EVI had an abnormal drop in 2018. This coincided with low precipitation and extremely high temperature in the early growing season, which may have caused water shortage and a decline in plant growth. Although the temperature was increasing significantly, the species diversity was slightly increasing in the first survey, but significantly decreased in the third survey. We suggest that the increase in temperature and the extension of the growing season might have led to the expansion of the bamboo species Y. niitakayamensis. Its expansion, combined with an extreme climate event could have caused the decline in species diversity.
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