Plant succession on abandoned fields after 25 years of shifting cultivation in Assuit, Egypt

摘要

The purpose of this study is to introduce the general trends in the various ecological characteristics of secondary succession occurring in abandoned fields after shifting cultivation in the Nile valley at Assuit, Egypt. The study examined, evaluated, and discussed the succession of the secondary growth of the plant communities in the abandoned fields inside Al-Azhar University campus at Assuit (constructed 25 years ago). It assessed the relationships between the environmental gradients, floristic composition, species richness, disturbance level, and size structures of woody plants. Seventy-eight species were recorded (46 annuals and 32 perennials). Four vegetation types were recognized after the application of TWINSPAN, DCA, and canonical correspondence analysis techniques and named after their dominant species as follows: Dichanthium annulatum-Pulicaria crispa, Pluchea dioscorides, Desmosta-chya bipinnata- Tamarix nilotica, and Desmostachya bipinnata- Ziziphus spina-christi. The notable environmental variables affecting the distribution of vegetation types in the study area were moisture content, disturbance level of stands, percentages of silt, clay, and K.