2.1. Site description
The quarries where the experimental restoration was carried out are at
the eastern border of Sierra de Gádor, 36o55´20´´N,
2o30´29´´W (Fig 1), 20 km NW of Almeria city, about
370 m a.s.l.
Climate is near the boundary between arid and semiarid, i.e, where the
aridity index (P/PET) is slightly below 0.2 (UNESCO, 1977). The data
from the Alhama de Almería station (AL003, Junta de Andalucía) show an
average annual precipitation, since the hydrological year 2002, of 241
mm, with a minimum annual of 106 mm and a maximum of 466 mm. The
hydrologic years just two years after the start of the experiment were
wetter than average (466 mm and 304 mm respectively), and the three
following years were much drier than average (167 mm, 202 mm and 165 mm,
respectively). Summers are particularly dry and temperatures are quite
high (averages 27°C in August with mean daily maximum above 35°C).
The natural soils around the quarries are either Calcaric Regosols or
Eutric Regosols (IUSS Working Group WRB 2015) which have formed over the
lithology of the area (marls and calcareous sandstones) and over mixed
slope deposits.
The vegetation around the quarries is essentially an alpha-grass
community, clearly dominated by Macrochloa tenacissima (L.)
Kunth, with some species of grasses, shrubs or dwarf shrubs such asDactylis hispanica Roth, Rhamnus lycioides L.,
Maytenus senegalensis Lam., Anthyllis cytisoides L.,
Anthyllis terniflora (Lag.) Pau, Thymus hyemalis Lange,Artemisia barrelieri Besser, Thymelaea hirsuta(L.) Endl., and Launaea
lanifera Pau. Some stands of Pinus halepensis Mill. are
found on favorable run-on locations and near a natural spring located
not far from the quarried area.