Annual temperature range
We use the annual temperature range (ATR) as the independent variable
for the climate variability hypothesis. To catch the precise
characteristics of climate, we set seven mini weather stations in Lebu
Valley (2,440, 2,822, 2,914, 3,311, 3,499, 4,219, 4,504 m a.s.l.). Each
mini weather station concluded two data loggers (HoBo Pro‐ RH/Temp and
HoBo Pro‐Precipitation/Temp) (Half a meter above the ground) and was
surrounded by fences to keep interference from wild animals. Annual
temperature maximum and annual
temperature minimum were recorded from 2018 to August 2019. ATR was
calculated as the annual temperature maximum minus annual temperature
minimum and then extrapolated to 26 elevational bands using the simple
ordinary least square (OLS) regression.