Table 1. Indicator species of the three types of ecosystem engineers and of bare soil identified by indicator species analysis performed on the “relevés x species individuals (number)” matrix, with the observed indicator value and significance level.

Group with maximum IV	Species	IV	Pa
Cushion	Calamagrostis sp.	0.595	***
	Parastrephia lucida	0.416	***
	Belloa kunthiana	0.401	***
	Poa aequigluma	0.383	***
	Nototriche turritella	0.355	**
	Festuca orthophylla	0.355	***
	Luzula racemosa	0.316	***
	Calamagrostis breviaristata	0.306	*
	Werneria aretioides	0.276	*
Shrub	Calamagrostis rigida	0.500	***
	Pycnophyllum molle	0.281	**
	Calamagrostis heterophylla	0.222	**
Tussock	Belloa longifolia	0.677	***
	Perezia ciliosa	0.365	***
	Perezia sp.	0.306	***
Bare soil	Viola granulosa	0.335	*

IV, observed indicator value.

^a P is the probability of type I error, namely the proportion of times that the maximum IV_i from the randomized data set (4,999 iterations) equals or exceeds the maximum IV_i from the actual data set, under the null hypothesis that the maximum IV_i is no larger than would be expected by chance

(*P < 0.05

**P < 0.01

***P < 0.001).

Only significant indicator values (P < 0.05) higher than 0.20 are shown.

Potential nurse species are in bold.