Population dynamics of Moringa peregrina along altitudinal gradient in the northwestern sector of the Red Sea

Moringa peregrina (Forssk.) Fiori is a desert tree of economic and medicinal importance. Because of the severe drought and the over-exploitation of seeds and cutting of trees for firewood, the species is threatened. The survival, mortality and reproduction were studied for eight populations of M. peregrina distributed along the species altitudinal range (550–1000 m a.s.l.) in the northwestern sector of the Red Sea. Survivorship curves, life tables and fecundity schedules are constructed for the studied populations. Populations are dominated by adult individuals and the seedling recruitment is extremely limited. The survivorship curves approach Deevey type III in which the highest mortality occurs in the early life stages. The highest expectation for future life is exhibited by juveniles. The net reproductive rate (R0) ranges from 0.0023 to 0.0040. The intrinsic rate of increase per capita per year (r) varies between −0.121 and −0.081, suggesting that the populations are declining and their survival cannot be ensured without conservation measures. The plant density, seed output, average number of seeds per individual (bx), net reproductive rate (R0) and intrinsic rate of increase (r) of populations decrease significantly with elevation. The phenological development of M. peregrina is delayed with increasing altitude. The results indicated that the populations of M. peregrina in the northwestern sector of the Red Sea are threatened, in particular those located at the highest elevations of the species altitudinal range. Due to the very limited seedling recruitment, conservation efforts should be directed mainly to the established individuals. Efforts should be made to minimize the uncontrolled exploitation of the species by local people. In situ and ex situ conservation of Moringa populations are strongly recommended.