Effect of a desert planted forest on the understory plant diversity: implication to conservation

The present study aimed to assess the potential role of desert tree plantations for biodiversity conservation of native vegetation. For this purpose, we compared diversity and composition of understory vegetation in a managed desert plantation in Egypt with adjacent natural vegetation. In 126 stands, we estimated the diversity indices of the understory vegetation associated with five tree plantations inside and outside the forest. The results showed that therophytes had the highest contribution to the total flora of the study area (45.7 %), followed by chamaephytes (21.7 %). The weed species were the main components inside the forest (37 species). In the stands of Eucalyptus camaldulensis and Khaya senegalensis, the agricultural weeds were the most abundant followed by natural weeds. Spring season was the main flourishing season for weeds followed by autumn. Dalbergia sissoo had the highest values for species richness (8.8) and the lowest for species turnover (2.5). On the contrary, Casuarina spp. had the lowest values of species richness (3.0) and the highest of species turnover (7.3) and Simpson index (12.3). Establishment of the forest leads to remarkable loss and changes in the biodiversity of natural desert vegetation and vegetation composition, respectively. Many ruderal weeds colonized the adjacent desert habitats. From this study, we concluded that forest managers should pay attention for the conservation and retention of existing native vegetation during their design for the desert plantations.