Restoration and Rehabilitation of Arid and Semiarid Mediterranean Ecosystems in North Africa and West Asia: A Review

background

This study systematically analyzes extensive literature on exclosures, afforestation, reafforestation, rehabilitation and other regeneration operations over several million hectares. It also includes 50 years of the author’s personal field experience in 17 of the 20 Mediterranean bioclimatic areas from the Atlantic Ocean to the Aral Sea.

Research Goals & Methods

This study reviews 46 range production experiments in West Asia and North Africa. In the study zone, the total area under temporary or permanent exclosure was 750,000 ha in Morocco, 450,000 ha in Tunisia, 850,000 ha in Algeria. These areas include National Parks and other protected zones.

Conclusions & Takeaways

The results show that productivity in exclosures averaged 2.8 times that of adjacent grazed areas while the variability of annual production decreased by 5% in exclosures versus the grazed areas. Exclosure permits the restoration and biological recovery of vegetation structure, composition and productivity over a period of 3-5 years in steppic ecosystems and 25-30 years in coniferous or sclerophyllic vegetation. In addition, controlled access and rationally managed utilization of land may achieve similar and sometimes better results than full exlcosure. Afforestation and reafforestation are usually more successful above the isohyet of 200mm mean annual rainfall, sometimes below as far as the selection of the species introduced or reintroduced is appropriate and degradation causes have been eliminated or minimized. Although rehabilitation operations may achieve quick success, these will be at a higher cost and may be subjected to constraints to techniques such as appropriate species and site selection and adequate subsequent management. The main constraints to ensuring the success of this National Regeneration Effort is the discontinuation of the situations that brought about degradation.