THE PHENOLOGY OF DESERT PLANTS - A 3-YEAR STUDY IN A GRAVEL DESERT WADI IN NORTHERN OMAN

The phenology of annual and perennial species in a gravel desert wadi in northern Oman and the effect of precipitation and air temperature o n the onset and duration of different phenophases is examined. The stu dy, which lasted 3 years, shows that the onset and duration of growth and flowering are correlated with the timing and abundance of precipit ation. Whereas variation in total rain does not affect the onset of fl owering in phanerophytes and chameaphytes, therophytes and geophytes a re affected. Late rain delays the onset of all phenological phases in all life-forms. Peak growth occurs fi om December to January and flowe ring from February to April depending on rain. Phanerophytes are least affected in their growth phenophase with less rain. Flowering in phan erophytes and chamaephytes occurs from 4 to 6 weeks after rain and in therophytes from 2 to 8 weeks after rain. The sequence of flowering fo r the majority of species is more or less constant despite differences in the timing and amount of rain. An assessment of climatic variabili ty for the area suggests that at least 10 years of study would be requ ired to encompass the full range of plant phenological patterns in a g ravel desert wadi in Oman. (C) 1997 Academic Press Limited.