Determinants and Congruence of Species Richness Patterns across Multiple Taxonomic Groups on a Regional Scale

Table 1

Variables used for the multiple regression modelling and multiple regression models established for species richness of different taxa. Listed are the beta coefficients and significance levels for the parameters in the final models established for five taxonomic groups. The explained variance in species richness for each taxonomic group is also shown. For spatial validation of models, the Spearman rank correlation coefficients 𝑟 of predicted and observed species richness values and the respective significance level are shown. *𝑃<0.05, **𝑃<0.01, ***𝑃<0.001, n.s.: nonsignificant parameters in the final model that improve the explanatory power of the model (AIC).

Variables (units)	Abbreviation	Amphibians	Reptiles	Grasshoppers	Plants	Mosses
Maximum observed number of species/grid cell	—	16	8	48	1180	400
CORINE 2000 land-cover classes
Deciduous forests (%)	DEW	—	—	—	—	—
Coniferous forests (%)	COW	—	—	—	−1.406*	—
Mixed forests (%)	MIX	—	—	—	—	—
Nonirrigated arable land (%)	NIA	—	—	—	−0.909*	−0.237**
Vineyards (%)	VIY	—	—	—	—	—
Orchards (%)	ORC	—	—	—	—	—
Meadows and pastures (%)	MEP	—	—	—	—	—
Natural grasslands (%)	NAG	—	—	—	—	—
Heathlands (%)	HEA	—	—	—	—	—
Shrublands (%)	SHR	—	—	—	—	—
Marshes (%)	MAR	—	—	4.061*	—	—
Flowing water bodies (%)	FLW	—	—	—	3.052*	—
Standing water bodies (%)	STW	—	—	—	—	—
Topography
Minimum elevation within grid cell (m)	HTMIN	—	—	—	—	−0.001**
Maximum elevation within grid cell (m)	HTMAX	—	—	0.075**	—	—
Landscape heterogeneity
Habitat heterogeneity^b	SIMPSON	0.374^n.s.	—	—	—	—
Range of elevation within grid cell (m)	HTDIFF	—	—	—	—	—
Climatic parameters 1961–1990 [27]
Mean annual temperature (°C)	TMPYEAR	0.065*	—	—	—	—
Mean sum of annual precipitation (mm)	PRECYEARSUM	—	—	—	—	—
Index of aridity^a	IOA	—	—	—	—	—
Mean temperature of the coldest month (January) (°C)	TMPJAN	—	—	1.269**	—	−0.064^n.s.
Spatial autocorrelation	SAC	0.053**	0.159***	0.409***	0.078***	0.005***
Number of plant species		not tested	not tested	0.071***	—	not tested
Model accuracy and validation
Goodness of fit (deviance change)		38.36%	33.76%	72.73%	62.34%	72.6%
Deviance change explained by environment		44.34%	—	45.42%	17.45%	7.05%
Deviance change explained by SAC		55.66%	100%	54.48%	82.55%	92.95%
ANOVA (versus Null model)		𝐹=11.826 ***	𝐹=14.145 ***	𝐹=69.621 ***	𝐹=79.886 ***	𝐹=124.61 ***
Spatial validation of the SAC model		0.758***	0.646***	0.752***	0.648***	0.721***
Spatial validation of the model without the SAC term)		0.606***	—	0.494***	0.326***	0.600***

^a mean temperature in July/mean annual sum of precipitation.
^bSimpson’s index of diversity using the relative proportion of the land-cover classes in grid cells.