Habitat heterogeneity
We extracted the land-cover type from the GlobeLand30
(http://www.globallandcover.com;
date of the download: 2019/3/25). We calculated
the number of land-cover types in each 1-km2 grid
cell. Ten land-cover types were classified by GlobeLand30. We combined a
30-m DEM and the 30-m landcover data of the study area to obtain the
landcover type in each 100-m elevational band. We extracted the cells of
the landcover raster data that correspond to the areas defined by the
30-m DEM for each 100-m elevational band using the extract by mask tool
in ArcGIS 10.4. We set the cell size of the result as the input DEM
data. In Lebu Valley, five landcover types (Cropland, Forest, Grass,
Water, and Ice) were defined. We calculated the habitat heterogeneity
(HH) using the Shannon diversity index. We also tested the relationship
between HH and the area percentage of suitable habitat types (forest and
grass). We compared the elevational pattern of the area percentage of
suitable habitat types and HH to test whether the area percentage of
suitable habitat types is large when the value of HH is high.