Table 2.
Main geological and climatic characteristics of study sites
| Study site | Substrate | pH | SOM (%) | N (%) | CaCO3 (%) | Gypsum (%) | P (mm) | T (ºC) | Altitude (m a.s.l.) | UTM |
|---|---|---|---|---|---|---|---|---|---|---|
| Ayerbe (Hu) | Miocene clays intermingled with marls | 8·2 | 1·2 | 0·11 | 31·1 | – | 630·2 | 13·2 | 580 | XM9280 |
| Huesca (Hu) | Miocene clays intermingled with marls | 8·3 | 0·4 | 0·04 | 37·8 | – | 587 | 13·4 | 488 | YM0560, YM0359 |
| Bernués (Hu) | Dominant sandstones intermingled with marls and conglomerates | 8·5 | 0·4 | 0·04 | 48·8 | – | 693·2 | 12·0 | 810–1020 | XN9704, YN0108 |
| Jaca (Hu) | Badlands on Eocene marls. | 8·2 | 0·6 | 0·05 | 39·0 | – | 824 | 11·4 | 920 | XN9913 |
| Las Peñas de Riglos (Hu) | Massive calcareous conglomerates | 7·9 | 6·7 | 0·36 | 2·4 | – | 1246·6* | 8·0* | 1380 | XN8908 |
| Lasieso (Hu) | Calcareous alluviums | 8·7 | 0·6 | 0·03 | 54·1 | – | 653·2 | 12·1 | 675 | YM1099 |
| Villamayor 1 (Z) | Gypsum sediments intermingled with marls and clays | 7·8 | 4·7 | 0·25 | 44·8 | 2·0 | 402·9 | 14·1 | 340 | XM8920 |
| Villamayor 2 (Z) | Powdery gypsum outcrops | 7·7 | 1·9 | 0·14 | 15·6 | 55·5 | 402·9 | 14·1 | 320 | XM8820 |
P = precipitation (mm) and T = temperature (°C): values were obtained from the closest weather station to the study population of each species (always located less than 10 km away from the study site). No weather information was available for the population of Echinospartum horridum (Las Peñas de Riglos, Huesca). Therefore, mean annual rainfall and temperature values for this site (*) were extrapolated from values recorded at the meteorological station of Jaca located 25 km away (31 years of record, 840 m a.s.l.), following the vertical gradients proposed for the Pyrenees by López-Moreno (2005) and García-Ruíz et al. (1985). Soil organic matter content (SOM, %) was analysed by the method of Walkley and Black (1934). Total N concentrations (N, %) were measured with an elementar analyser (Elementar VarioMAX N/CM, Hanau, Germany). Carbonate content (CaCO3, %) was assessed by Bernard's calcimetry (Porta-Casanellas et al., 1986) and gypsum content (%) was determined with a C/S elementar analyser (ISC144DR, Leco, St Joseph, Michigan).