DIVERSITY AND DISTRIBUTION OF SOIL SEED BANKS AND PLANT LITTER IN AL WADI AL AKHDAR (THE GREEN VALLEY) OF TABUK REGION - SAUDI ARABIA

We explored the species composition, diversity, and spatial distribution of soil seed banks and plant litter at two sites within Al Wadi Al Akhdar 'the green valley' area of Tabuk region, KSA, the main valley, and an adjoining shallow stream which are in essence different in elevation, slope and amount of overflow. The objectives were to evaluate and detect the species diversity and spatial variability in soil seed banks and plant litter. We used the systematic sampling procedure to collect soil samples, and the flotation method to extract seeds and plant litter. We employed Paleontological Statistics (PAST) version 4.03 to achieve summary statistics, diversity indices, and graphs and drive appropriate statistical tests that are crucial to answering research questions. Seed banks and plant litter exhibited abnormal spatial distributions. Differences in the mean number of seeds and plant litter contents between sampling points and between the two sites were not significant (p <= 0.05). The shallow stream was more diverse in seed species with a high evenness of distribution between species compared to the valley. The valley possessed a higher number of seeds with a higher dominance _ D value. Species within the shallow site varied significantly (p <= 0.05) in their mean number of seeds, but the difference between the valley species was not significant. Senecio sp. seeds dominated the seed bank of the valley, while Brassica sp. seeds dominated the shallow stream seed bank. The seed banks of both sites were made of herbaceous species. The parent plants of seed banks do not belong to the standing vegetation. We concluded that elevation and slope influenced soil seed banks' spatial distribution, diversity, and plant litter.