Species occurrence data for 30 tree species in Switzerland (SWI, a country in Europe) and associated environmental data. Full details of the dataset are provided in the reference below. There are four data sets with training (po and bg) and test (pa, env) data:
po (training data) includes site names, species names, coordinates, occurrence ("1" for all, since all are presence records), group (tree), and site values for 13 environmental variables (below).
bg (training data) has 10000 sites selected at random across the study region. It is structured identically to po, with "0" for occurrence (not implying absence, but denoting background in a way suited to most modelling methods) and NA for group.
env (testing data) includes group, site names, coordinates, and site values for 13 environmental variables (below), at 10103 sites. This file is suited to making predictions.
pa (testing data) includes group, site names, coordinates, and presence-absence records, one column per species. The sites are identical to the sites in env. This file is suited to evaluating the predictions made to env.
Raster (gridded) data for all environmental variables are available - see the reference below for details.
The reference system of the x and y coordinates is Transverse, spheroid Bessel (EPSG:21781) (note all SWI data has a constant shift applied).
The vignette provided with this package provides an example of how to fit and evaluate a model with these data.
Environmental variables:
| Code | Description | Units | Type |
| bcc | Broadleaved continuous cover (based on Landsat images) | percentage | Continuous |
| calc | Bedrock is strictly calcareous | 1 (yes) or 0 (no) | Categorical |
| ccc | Coniferous continuous cover (based on Landsat images) | percentage | Continuous |
| ddeg | Growing degree-days above a threshold of 0 degrees C | degrees C * days | Continuous |
| nutri | Soil nutrients index between 0-45 | D mval/cm2 | Continuous |
| pdsum | Number of days with rainfall higher than 1 mm | ndays | Continuous |
| precyy | Average yearly precipitation sum | mm | Continuous |
| sfro | Summer Frost Frequency | days | Continuous |
| slope | Slope | degrees x 10 | Continuous |
| sradyy | Potential yearly global radiation (daily average) | (kJ/m2)/day | Continuous |
| swb | Site water balance | mm | Continuous |
| tavecc | Average temperature of the coldest month | degrees C | Continuous |
| topo | Topographic position | dimensionless | Continuous |
Elith, J., Graham, C.H., Valavi, R., Abegg, M., Bruce, C., Ferrier, S., Ford, A., Guisan, A., Hijmans, R.J., Huettmann, F., Lohmann, L.G., Loiselle, B.A., Moritz, C., Overton, J.McC., Peterson, A.T., Phillips, S., Richardson, K., Williams, S., Wiser, S.K., Wohlgemuth, T. & Zimmermann, N.E., (2020). Presence-only and presence-absence data for comparing species distribution modeling methods. Biodiversity Informatics 15:69-80.
swi_po <- disPo("SWI")
swi_bg <- disBg("SWI")
swi_pa <- disPa("SWI")
swi_env <- disEnv("SWI")
x <- disData("SWI")
sapply(x, head)
disCRS("SWI")
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