Table 2.

Groups of variables used to explain rooting parameters, including information on the type (V, vegetation variable; S, site variable; and LU, land-use variable), the number of variables of each group (no.) and examples (for details, see Appendices S1, S3 and S4).

Group of variables	Type	no	Examples
Richness	V	14	Total vascular plant species number, species numbers of different taxonomical groups and functional types
Community composition	V	7	Total vegetation cover, mean species cover, plant cover variance or dominance of individual species, Shannon–Wiener and Evenness index of species abundance
Cover of functional types	V	15	Relative abundance of functional types (lichen, mosses, ferns, true grasses/Poaceae, rush grasses/Juncaceae, sedges/Cyperaceae, legumes, non-legume forbs, dwarf shrubs, trees), Shannon–Wiener and Evenness index of functional types
Community-level traits	V	17	Traits (rooting density, rooting depth, leaf area, plant height), Shannon–Wiener and Evenness index of functional traits
Site characteristic	S	19	Climate (temperature and precipitation), elevation, soil depth, soil physical and chemical properties, geological basis
Land-use type and intensity	LU	6	Arable land, intensively used hay meadow, lightly managed hay meadow, pasture, agriculturally unused grasslands, forest