Spatial and temporal plant phenological niche differentiation in the Wadi Degla desert ecosystem (Egypt)

Abstract

AbstractTwenty dominant plant species representing different life forms were investigated phenologically over a period of 36 months (January 2004 to December 2006). Plant populations were sampled at down-, mid-, and upstream sites in a desert wadi ecosystem. The results were analyzed using TWINSPAN, DCA and CCA techniques. Five phenological niches were apparent: (1) species flowering all year round, with peaks in spring and autumn such asOchradenus baccatus; (2) species flowering during winter includingLycium shawiiandTamarix nilotica; (3) species flowering during spring, e.g.,Zillaspinosa, Zygophyllum coccineumandCapparis spinosa; (4) species flowering during summer includingIphiona mucronataandDeverra triradiata; and (5) species flowering during autumn that includeAtriplex halimusand twoAnabasisspecies. The climatic variables, including temperature, rainfall and relative humidity, affect the phenological niches and between-species differences. Within-species variations occurred between years and there were no between-site variations for most study species. The different plant species exhibited phenological diversity along the course of the wadi ecosystem. The phenological niches are species-specific and environmentally dependent rather than local selective pressures.