Artificial forests as conservation sites for the native flora of the UAE

The results showed insignificant variation in species richness and species diversity index among the six studied forests. The effects of type and size of trees grown in the forest trees were significant on all the studied community attributes. All the attributes were significantly greater inside than outside forests cultivated with the native Prosopis cineraria (L.) Druce and Acacia arabica (Lam.) Willd. trees. The reverse was true in forests cultivated with exotic Eucalyptus sp. and Prosopis juliflora trees. It is recommended, therefore, that exotic trees be replaced with native ones, in order to promote species richness and diversity. Species richness, diversity and density were higher under medium than under large size P. cineraria trees. This suggests the importance of reducing forest crowns to promote species growth. The palatable Panicum turgidum and Pennisetum divisum grasses attained significantly high frequencies and densities inside the forests, but were not recorded at all outside. The reverse was true for other non-palatable species. Afforestation significantly reduced soil pH under and between the tree crowns, compared to outside them. Organic matter content, salinity, total sodium ions, total sulfate, total soluble nitrogen, total chromium and copper attained significantly greater values under the crowns of the trees than both between the crowns and outside the forests. The great increase in soil salinity, especially Na ions, is an indicator of the high salinity in irrigation waters. Afforestation in the UAE can be an effective tool to promote diversity and improve soil quality, provided afforestation programs are carefully planned and well executed, because any miscalculations could lead to serious environmental damages.