Table 1.
Variables used in the modeling.
| Variable | Description | Date | Resolution | Source |
|---|---|---|---|---|
| Bio1 | Annual mean temperature | 1970–2000 | 30 arc sec | WorldClim a |
| Bio2 | Mean diurnal range | 1970–2000 | 30 arc sec | WorldClim a |
| Bio3 | Isothermality | 1970–2000 | 30 arc sec | WorldClim a |
| Bio4 | Temperature seasonality | 1970–2000 | 30 arc sec | WorldClim a |
| Bio5 | Maximum temperature of the warmest month | 1970–2000 | 30 arc sec | WorldClim a |
| Bio6 | Minimum temperature of the coldest month | 1970–2000 | 30 arc sec | WorldClim a |
| Bio7 | Temperature annual range | 1970–2000 | 30 arc sec | WorldClim a |
| Bio8 | Mean temperature of the wettest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio9 | Mean temperature of the driest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio10 | Mean temperature of the warmest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio11 | Mean temperature of the coldest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio12 | Annual precipitation | 1970–2000 | 30 arc sec | WorldClim a |
| Bio13 | Precipitation of the wettest month | 1970–2000 | 30 arc sec | WorldClim a |
| Bio14 | Precipitation of the driest month | 1970–2000 | 30 arc sec | WorldClim a |
| Bio15 | Precipitation seasonality | 1970–2000 | 30 arc sec | WorldClim a |
| Bio16 | Precipitation of the wettest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio17 | Precipitation of the driest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio18 | Precipitation of the warmest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| Bio19 | Precipitation of the coldest quarter | 1970–2000 | 30 arc sec | WorldClim a |
| NDVIMAX | Maximum NDVI | 2010 | 250 m | MODIS b |
| NDVIMIN | Minimum NDVI | 2010 | 250 m | MODIS b |
| NDVIMEAN | Average NDVI | 2010 | 250 m | MODIS b |
| Elevation | Elevation above sea level | 2017 | 250 m | STRM c |
| Slope | Slope | 2017 | 250 m | STRM c |
| Aspect | Aspect ratio | 2017 | 250 m | STRM c |
| Human | Human population density | 2010 | 1 km | CAS d |
| Pig | Pig density | 2006 | 1 km | Geo-Wiki e |
a WorldClim Global Climate database version 2, available at: http://worldclim.org/version2; b Moderate Resolution Imaging Spectrometer (MODIS), available at: https://lpdaac.usgs.gov/; c Shuttle Radar Topography Mission (SRTM) 250 m digital elevation data version 4.1, available at: http://srtm.csi.cgiar.org//; d Human population density grid data of China, obtained from the Chinese Academy of Sciences (CAS); e Global Pig density grid data, available at: http://www.livestock.geo-wiki.org.