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 on the onset and duration of different phenophases is examined. The study, which lasted 3 years, shows that the onset and duration of growth and flowering are correlated with the timing and abundance of precipitation. Whereas variation in total rain does not affect the onset of flowering in phanerophytes and chameaphytes, therophytes and geophytes are affected. Late rain delays the onset of all phenological phases in all life-forms. Peak growth occurs from December to January and flowering from February to April depending on rain. Phanerophytes are least affected in their growth phenophase with less rain. Flowering in phanerophytes and chamaephytes occurs from 4 to 6 weeks after rain and in therophytes from 2 to 8 weeks after rain. The sequence of flowering for the majority of species is more or less constant despite differences in the timing and amount of rain. An assessment of climatic variability for the area suggests that at least 10 years of study would be required to encompass the full range of plant phenological patterns in a gravel desert wadi in Oman.