Stipa tenacissima L. (Alpha grass) steppes cover 32,000 km2 in the western Mediterranean basin. These are the remains of an estimated 86,500 km2 area covered by this species some decades ago (Le Houérou 1995).
Alpha steppes are mostly distributed in a thin latitudinal fringe in North Africa, from Libya to Morocco, and in the southeastern portion of the Iberian peninsula, where they cover ca. 6,000 km2.
Stipa tenacissima is of Asiatic origin, and it probably arrived in the SE Mediterranean during the Messinian crisis, 6.5 to 5.0 million years ago (Blanco et al. 1997), when large parts of the current Mediterranean basin dried out. Later, expansion was favoured by humans, as they removed accompanying woody vegetation (Barber et al. 1997, Buxó 1997). There is evidence of deforestation occurring in the area as early as the Copper Age (prior to 4,000 years BP), and artifacts made from S. tenacissima leaves, such as baskets, strings and shoes, dating back 3,000 years BP have been found in archaeological sites (Díaz-Ordoñez 2006).
Alpha steppes occupied vast extensions in southeastern Spain during Roman times (1st century): a dry area estimated at 50 x 150 km close to Carthago Nova (currently Cartagena) was named ‘campus spartarius’ (literarily meaning ‘esparto grass field’) by Pliny the Elder (Blanco et al. 1997). The importance of S. tenacissima for weaving and high quality paper paste increased up to the early 20th century, and there are records of local shortage of S. tenacissima fiber as early as 1879 (Hernández 1997). Several government agencies were created in the mid 20th century to foster this crop, such as the National Esparto Grass Service (Servicio Nacional del Esparto; 1948), launched by the Ministry of Industry and Commerce and the Ministry of Agriculture. However, the use of plastic fibers and rural exodus forced a sharp decline in S. tenacissima cropping, that almost disappeared by the end of the century.
Stipa tenacissima is still used in North Africa, where it provides pastures and fiber for paper mills (e.g., as much as 250,000 Mg of raw cellulose and high quality paper paste in Kasserine factory in Tunisia, and Baba Ali and Mostaganen in Algeria; El Hamrouni 1989), and its cropping and marketing may be fostered in SE Europe due to renewed interest in natural resources and traditional handcrafts which employ them.
Ibero-North African steppes are rich in endemic species. For example, close to 20% of the vascular plants in Spanish and North African steppes are endemic. But suppression of woody vegetation has probably had a strong impact on the abundance of vascular plants in S. tenacissima steppes (Maestre and Cortina 2004a). It is worth noting that biological crusts formed by mosses, lichens and cyanobacteria, are common in these steppes. These may also show high diversity (e.g. >15 taxa of cyanobacteria in 22 cm2; Maestre et al. 2006a).
Stipa tenacissima steppes constitute an excellent model ecosystem to expand our knowledge of ecosystem dynamics in semi-arid lands because of their broad geographical distribution and their strong and long-term links with human activities. In addition, the wide variety of conditions characterising S. tenacissima steppes make this ecosystem particularly suitable to test the theoretical background of restoration ecology, and explore new approaches for the restoration of semi-arid areas.