American Journal of Plant Sciences, 2014, 5, 899-906 Published Online March 2014 in SciRes. http://www.scirp.org/journal/ajps http://dx.doi.org/10.4236/ajps.2014.57102 How to cite this paper: Abdallah, F. and Chaieb, M. (2014) Changes in Vegetation Proprieties under Short- and Long-Term Protection in North African Arid Land. American Journal of Plant Sciences, 5, 899-906. http://dx.doi.org/10.4236/ajps.2014.57102 Changes in Vegetation Proprieties under Short- and Long-Term Protection in North African Arid Land Fathia Abdallah * , Mohamed Chaieb Department of Biology, Faculty of Sciences, University of Sfax, Sfax, Tunisia Email: * f.abdallah1@voila.fr Received 9 December 2013; revised 5 February 2014; accepted 26 February 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract The objective of this study was to quantify the effects of protection on herbaceous species compo- sition, total plant cover, dry matter, plant density, floristic richness and diversity. Characteristics of vegetation under continued grazing and protected area for 10 and 65 years were examined in a degraded arid environment in South Tunisia. Our results show that protection enhances signifi- cantly (two times) different vegetation parameters. However, long-term protection was found to reduce biomass production, plant density and floristic diversity. Some palatable species such as Stipagrostis ciliata, Helianthemum sessiliflorum, Eragrostis papposa, Echiochilon fruticosum and Cenchrus ciliaris were frequently found in the protected sites. In the grazed site, these species were being replaced by less desirable species: Astragalus armarus, Peganum harmala and Artemi- sia compestris. This emphasized the importance of conservation stocking rates and proper pasture management. Keywords Arid environment; Protection; Vegetation; Grazing 1. Introduction Livestock grazing is one of the main causes of degradation in arid and semi-arid ecosystems [1]-[3]. Grazing frequently operates through the reduction of plant cover and fragmentation followed by disappearance of vege- tation patches, reducing their size and/or numbers [4] and leading to soil erosion and losses of nutrients from the exposed soil [5]. Grazing increased, reduced or lacked consistent effect on plant diversity [6]. These contrasting * Corresponding author.