Assigning life-history traits to plant species to better qualify arid land degradation in Presaharian Tunisia

Apart from a decrease in total perennial plant cover, degradation of North-African arid lands is not easy to qualify. Yet, simple and comprehensive yardsticks are necessary to assess degradation. We assigned components of competitive ability (C), stress tolerance (S) and ruderality (R) to 15 common perennials of Presaharian Tunisia. We used for that purpose phyto-ecological studies, data about life-form, grazing value and demography and circumstantial data. Assigning CRS-strategies to these species improves understanding of vegetation change under increased anthropic influence, helps to conceive experiments to confirm underlying hypotheses and sheds another light on the controversy about restoring arid lands.