Table 1.
Explanatory variables analysed during the modelling process and their source. Variable names (second and forth columns), their codes (first and third columns) and factors grouping them (inserted sections). The resolution of the variables when coming from a raster are indicated in brackets next to the factor in which are grouped, in italics. The codes of the variables selected after the multicollinearity evaluation are shown in bold
| Code | Variables | Code | Variables |
|---|---|---|---|
| Spatial | |||
| YSp | Spatial logit (linear polynomial combination of Latitude (°N) and Longitude (°E) from the spatial logistic regression)(1) | ||
| Topography (1 km × 1 km of original resolution) | |||
| A | Average altitude (m)(2) | S | Slope (◦) (calculated from Altitude) |
| Ori-NS | Orientation; degrees of exposure NS (calculated from Slope) | Ori-EW | Orientation; degrees of exposure EW (calculated from Slope) |
| Climatic (1 km × 1 km of original resolution) | |||
| BIO1 | Average annual temperature (°C)(3) | BIO11 | Mean annual temperatures of the coldest quarter (°C)(3) |
| BIO2 | Mean diurnal range temperatures (°C)(3) | BIO12 | Annual precipitation (mm)(3) |
| BIO3 | Isothermality (BIO2/BIO17) (*100) (°C)(3) | BIO13 | Precipitation of the wettest month (mm)(3) |
| BIO4 | Seasonality of temperatures (°C)(3) | BIO14 | Precipitation of the driest month (mm)(3) |
| BIO5 | Maximum temperatures of the warmest month (°C)(3) | BIO15 | Seasonality of precipitation (mm)(3) |
| BIO6 | Minimum temperatures of the coldest month (°C)(3) | BIO16 | Precipitation of wettest quarter (mm)(3) |
| BIO7 | Annual temperature range (BIO5-BIO6)(3) | BIO17 | Precipitation of dry quarter(3) |
| BIO8 | Mean annual temperatures of the wetter quarter(3) | BIO18 | Precipitation of warmest quarter(3) |
| BIO9 | Mean annual temperatures of the dry quarter(3) | BIO19 | Precipitation of coldest quarter(3) |
| BIO10 | Mean annual temperatures of the warmest quarter(3) | PMax | Maximum average precipitation in 24 h (mm)(3) |
| BhPri | Spring water balance (mm)(3) | ETR | Monthly real evapotranspiration (mm)(3) |
| Vegetation (1 km × 1 km of original resolution) | |||
| NDVI | Index of greenness(4) | ||
| Geography | |||
| DistCost | Distance to coast (km)(5) | ||
| Hydrology | |||
| DistRiver | Minimum distance to rivers (km)(6) | LonRiver | Longitude of rivers (km)(6) |
| Land use | |||
| Forests | Forests (%)(7) | Reforests | Reforestation (%)(7) |
| NatField | Natural field (%)(7) | Crops | Crops (%)(7) |
| Wetland | Wetland (%)(7) | ||
| Lithology | |||
| DepthSoil | Depth of soil(8) | TextSoil | Soil texture(8) |
| RockySoil | Rocky soil(8) | FloodSoil | Flood soil(8) |
| Human activities (1 km × 1 km of original resolution) | |||
| PobDen | Population density(9) | DistUrban | Minimum distance to the main urban centers (Km)(10) |
| DistRoad | Minimum distance to paved roads (km)(11) | DistUnpavRoad | Distance to unpaved roads (km)(11) |
Sources:
(1) Spatial variables, latitude, and longitude, were generated using the vector geometry tools of QGIS (http://www.qgis.org) software: (a) "centroids of polygons" was used to calculate the centroid of each grid cell was calculated; and (b) "Export/Add columns of geometry" was used to express the length and latitude values (1984 World Geodetic System) assigned to each centroid (WGS84)
(2) United States Geological Survey (1996). GTOPO30. Land Processes Distributed Active Archive Center. EROS Data Center: https://lta.cr.usgs.gov/GTOPO30. (accessed April 2016)
(3) Ceroni (2008) from DNM-INIA. Monthly data series for 30 years for Uruguay (from 1980 to 2009). We calculated the bioclimatic variables (BIO1–BIO19) following the proposal used in WorldClim (Fick & Hijmans, 2017)
(4) https://www.vito-eodata.be: from SPOT-VEGETATION – S10 NDVI
(5) Generated using QGIS (http://www.qgis.org) software by calculating the average distance from the centroid of the grid cell to the coastline
(6) United States Geological Survey (2006). HydroShed. Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales. Available at: http://hydrosheds.cr.usgs.gov/index.php/ (accessed May 2016)
(7) GlobCover (2009). Global land cover map. Available at: http://due.esrin.esa.int/page_globcover.php (accessed April 2016)
(8) Panario & Gutiérrez (2011). Mapa de ambientes: Cartografía implementada en un SIG. In: Mapa de Ambientes de Uruguay y Distribución potencial de especies, Convenio MGAP/PPR-CIEDUR, Montevideo
(9) Gridded Population of the World (GPWv4) (2010). Socioeconomic Data and Applications Center (SEDAC). A Data Center in NASA's Earth Observing System Data and Information System (EOSDIS)—Hosted by CIESIN at Columbia University (accessed June 2016)
(10) Natural Earth Data. North American Cartographic Information Society (NACIS). Available at: http://www.naturalearthdata.com/ (accessed April 2016)
(11) Digital Chart of the World. Available at: https://worldmap.harvard.edu/data/geonode:Digital_Chart_of_the_World (accessed April 2016)