Adaptabilité des espèces du genre <i>Atriplex</i> aux conditions de salinité et d'aridité

Plants have had to cope with periodic, unpredictable environmental stresses during growth and development. Surviving such stresses over a long evolutionary scale led plants to acquire mechanisms allowing them to sensitively perceive stresses and regulate their physiology accordingly. In the arid and semi arid regions of the world, shrubs surviving in saline soils have been the subject of considerable research. They have been evaluated as alternative sources of forage for livestock. Thus, Rehabilitation of rangelands with shrubs can add to feed resources and stop land degradation. The genus Atriplex (Chenopodiaceae) is a perennial halophyte witch is distributed all over the world and widely used in rehabilitation programs. Atriplex spp are strong candidates for cultivation because of their adaptation to the climate and soil and mainly for their nutritive value for grazing animals during the hardest periods of the year. The aim of this study is to evaluate the adaptability of two species, A. nummularia et A. halimus to conditions of drought and salinity under controlled and field conditions. The effect of two irrigation regimes and of an increasing salinity were tested. Moreover, propagation, cutting intensities to simulate browsing, nutritive value, growth under rainfed conditions of 30 clones of A. halimus were studied to select some clones with both good nutritive value and abiotic stress resistance to act upon plant improvement programs for salinity and drought conditions

Approccio partecipativo per lo sviluppo integrato e la gestione delle zone marginali in Nord Africa: progetto dimostrativo di lotta alla desertificazione in Marocco e Tunisia

Nelle zone aride e semiaride, l’agricoltura e la pastorizia rappresentano fondamentali risorse per la sussistenza delle popolazioni locali. Nonostante la loro importanza strategica, in queste aree, le produzioni risultano sovente limitate e irregolari, manifestando un grosso limite allo sviluppo delle attività agropastorali. Gli ecosistemi dei territori interessati si presentano spesso fragili, a causa dell’azione combinata di fattori climatici e delle attività umane. L'aratura e la rimozione indiscriminata della vegetazione, insieme all’irregolarità e all’insufficienza delle piogge sono spesso responsabili di fenomeni di degrado dei suoli, distruzione su grande scala della copertura vegetale e desertificazione. La crescente domanda di foraggio per gli allevamenti, di gran lunga superiore alla produttività dei pascoli (Le Houerou, 1990; 2000), ha provocato un aumento della pressione sul pascolo e la messa in coltura ad orzo di terre tradizionalmente adibite esclusivamente a pascolo, causando una accelerazione dei fenomeni di degrado del suolo (Abu Zenat et al. 2004). Inoltre, si è evidenziato un impoverimento qualitativo dei pascoli, dove le specie di alto valore foraggero sono spesso sostituite da piante meno produttive, meno appetibili e meno nutrienti di quelle originali (Juneidi and Abu-Zanat, 1993). In questo contesto, l’impianto di arbusti foraggeri garantisce la copertura vegetale del suolo, offrendo protezione contro l’erosione e rappresenta una potenziale risorsa di foraggio e legna da ardere (Mulas e Mulas, 2004). Le specie Opuntia ficus indica, particolarmente tollerante all’erosione idrica ed eolica (Nefzaoui et al. 2000), e Atriplex nummularia, perfettamente adatta ai climi mediterranei aridi o semiaridi (Hyder ed Akil, 1987), sono le più impiegate nelle regioni del Nord Africa e Medio Oriente. In questo lavoro si riportano i risultati di un intervento di sviluppo integrato, basato sull’impianto di Opuntia ficus indica e Atriplex sp.pl., nell’ambito del progetto europeo SMAP II “Demonstration Project on Strategies to Combat Desertification in Arid Lands with Direct Involvement of Local Agropastoral Communities in North Africa ” coordinato da NRD-UNISS e realizzato in aree aride e semiaride degradate di Marocco e Tunisia

Participatory approach for integrated development and management of North African marginal zones: demonstrative plan to fight desertification in Morocco and Tunisia

A demonstrative and participatory development project on desertification mitigation and rural development has been launched in Northern Africa under SMAP Programme (Short and Medium-term priority environmental Action Programme) financed by the European Union. The project, which title is Demonstration Project on Strategies to Combat Desertification in Arid Lands with Direct Involvement of Local Agro-pastoral Communities in North Africa, is carried out in sensitive regions of Morocco and Tunisia with the coordination of the Nucleo Ricerca sulla Desertificazione (NRD, Desertification Research Center) of the University of Sassari (Italy) and the partnership of Morocco and Tunisia Agriculture Ministries. The areas concerned are located in regions characterised by rural poverty, food dependency and land abandoning where urgent measures are needed to promote optimisation of resource availability and management for a sustainable development. The project involves direct desertification mitigation by vegetation cover restoration, with drought resistant perennial forage species (Opuntia ficus-indica, Atriplex nummularia and Acacia saligna) in highly degraded rangelands in order to mitigate desertification processes while improving rangelands productivity; and adopts measures for local population technical capacities building through training sessions related to all project activities, and making it a concrete demonstration supported by the direct involvement of local communities. Successful actions already carried out in this field by the participants of the project as well as by other Mediterranean countries, has been taken into account, re-elaborated and exploited, thus promoting south/south co-operation and exchange of knowledge. Participation of all actors and especially of local communities is the key point in all phases of the project and is strengthened by means of dissemination and sensitisation campaigns and by training courses. At the end of the project, all actors own/share all choices made and the technology used participating thus to the intervention sustainability

The SWAT model to assess hydrological processes in arid environment (SE Tunisia), in the frame of WADIS-MAR project

Arid regions of Maghreb (North Africa) suffer scarce water conditions and the erratic behaviour of rainfall events over brief intervals often produce short and intense floods events which converge into ephemeral wadi beds. The watershed of wadi Oum Zessar, in South-East Tunisia, is characterized by a rainfall rate of about 200 mm/year, overexploitation of groundwater resources and is highly exposed to climate change risk and desertification processes (Ghiglieri et al., 2014). This region represents one of the two study areas in the framework of WADIS-MAR demonstration project (www.wadismar.eu), funded by the European Commission under the Regional Programme SWIM (www.swim-sm.eu). WADIS-MAR Project aims: (i) to improve the traditional water harvesting systems (i.e. jessour and tabias) by applying “soft” modern rehabilitation interventions; (ii) to increase groundwater availability through managed aquifer recharge (MAR) systems (i.e. gabions, recharge wells, recharge trenches). Jessour andtabias capture surface runoff coming from degraded and rocky rangelands for crop production (fruit trees, mainly olives, and cereals) in upstream subbasins. The objective of this study was to assess the main hydrological processes and the sediment loads in this arid environment, by using the Soil and Water Assessment Tool (SWAT) model. Sediment load is an important parameter to be considered in the MAR systems because it may causes the clogging of the infiltrating surface, resulting in the reduction of water infiltration rates. The watershed delineation used the newly 2014 released SRTM 1 Arc-Second digital elevation model, available at www.earthexplorer.usgs.gov. A land cover classification obtained by visual interpretation of Landsat data was used for the modelling. Conversion to land use was supported by ancillary and detailed ground truth data. The classic version of SWAT was adjusted to adapt the model to this dry Mediterranean environment (Ouessar et al., 2009). In SWAT, subbasin may be divided into Hydrologic Response Units (HRUs) which possess unique landuse/management/soil attribute. Normally, the runoff from all HRUs is added directly to the outlet of the subbasin. In this study runoff is routed between HRUs within the subbasin. The main adjustment consists of allowing the simulation of the runoff collection behind the water harvesting structures by bringing the surface runoff and lateral flow generated by different HRUs within the same subbasin. Moreover, existing gabions and recharge wells were considered in the model for a more accurate simulation of the hydrological processes. Possible coupling with MODFLOW will be considered. After calibration and validation, the model will be also used for evaluating the efficiency of the MAR systems which are being realized within the WADIS-MAR project