Table 1. Results from a spatial autoregressive (SAR) modelling on species richness in grassland plant communities within the French Alps.

Only the environmental variables selected on a forward stepwise selection are shown at each resolution. Values in each column represent the estimated coefficient value for each variable, with the corresponding standard error and significance level (P-value). At each resolution we also show the number of grid cells in the analysis (n), the number of community plots per grid cell, and the total explained variance (R²).

	Estimate ± SE	P-value
1 km (n = 284, 3 plots per cell, R2 = 0.26)
Intercept	27.86 ± 0.34	<0.001
Temperature of coldest month	3.22 ± 0.33	<0.001
Slope	1.73 ± 0.23	<0.001
Elevation	−1.55 ± 0.27	<0.001
YSD temperature of coldest month	−1.63 ± 0.36	<0.001
5 km (n = 121, 5 plots per cell, R2 = 0.29)
Intercept	364.47 ± 13.85	<0.001
SSD growing degree-days	24.39 ± 8.96	0.006
Percentage calcareous soil	27.99 ± 10.77	0.009
Topographic wetness index	−33.45 ± 10.04	<0.001
YSD annual precipitation	−37.23 ± 12.42	0.003
10 km (n = 69, 10 plots per cell, R2 = 0.60)
Intercept	−239.65 ± 360.62	0.51
SSD growing degree-days	0.04 ± 0.01	0.001
YSD annual temperature	165.54 ± 56.14	0.003
SSD percentage calcareous soil	2.23 ± 0.59	<0.001
Elevation	0.20 ± 0.08	0.010
YSD annual precipitation	−0.87 ± 0.26	<0.001
Percentage calcareous soil	0.80 ± 0.27	0.003
SSD topographic wetness index	−96.18 ± 41.05	0.019
20 km (n = 37 grid cells, 20 plots per cell, R2 = 0.47)
Intercept	834.12 ± 45.18	<0.001
YSD annual temperature	74.38 ± 20.18	<0.001
SSD percentage calcareous soil	52.24 ± 18.30	0.004
30 km (n = 25 grid cells, 30 plots per cell, R2 = 0.63)
Intercept	962.39 ± 49.14	<0.001
SSD temperature of coldest month	55.60 ± 15.02	<0.001
SSD summer moisture index	−47.95 ± 17.93	0.007

SE, standard error; SSD, spatial standard deviation; YSD, yearly standard deviation.