Vegetation ecology and ethnobotany of Cyphostemma digitatum in the Western Highlands in Yemen
The project was motivated by the problem of overexploitation of the plant species Cyphostemma digitatum (Vitaceae), traditionally used in Yemen for culinary and medical purposes. It is aimed to restore this plant and the culture of its use. First the antioxidant capacity and the total phenolics of the processed form and the raw material were examined. No or very weak correlations were found between these. This led to investigate other functional food ingredients standing behind the antioxidant capacity. Rather high contents of vitamin C, vitamin E, and carotenoids were found. Some of the carotenoids along with vitamin C were reduced by processing, while vitamin E was enhanced. This implied that carotenoids give the characteristic aroma. A descriptive analysis of the volatiles was done and remarkable ones were described according to their retention times. The results underline that C. digitatum will become an important source of nutrition for general and specific health purposes. The ecological situation of C. digitatum was assessed based on Braun-Blanquet approach coupled with multivariate statistical tools, which ended with seven distinct communities harbouring that species. Two of them are frost tolerant vegetation; four are frost free vegetation, while one is a transition community. With respect to the holistic concept a predictive habitat model for these community types were constructed by a nonparametric multiplicative regression approach. Mathematical evaluation based on resubstitution method classified the resulting models as rather good. The predictive vegetation model led to find and record the species far away from the overexploited areas, sometimes with different ecological conditions. Consequently a higher accuracy individualistic prediction map for C. digitatum could be constructeded afterwards because of the iteration between species and vegetation modelling. Hence, areas of high suitability can now be detected and used for species restoration.