Survey of Soil Seed Bank in Three Watersheds across Nnamdi Azikiwe University, Awka Campus, Nigeria

Abstract

Soil seed banks survey of three watersheds located across the Awka campus of Nnamdi Azikiwe University was carried out using standard field procedures. Soil samples were collected from two points (P1 and P2) in each of the watersheds at depths of 0-5cm, 5-10cm and 10-15cm. The soil samples collected were spread and watered daily to allow sprouting of seeds. After germination, plants were allowed to grow for an additional 2 weeks; taxonomic identification and classification of all the plant species in every soil sample collected was carried out. The plant species were identified and classified considering observable morphological features with the aid of a flora. The abundance measures analyzed includes: density, frequency, relative density, relative frequency, importance value, species diversity using Shannon-Wiener index. A total of one hundred and eighty-seven (187) plants germinated from the total of eighteen soil samples collected from different points at the study sites. Twenty five (25) species of plants were identified within 13 families. The study revealed that the families Fabaceae, Amaranthaceae and Solanaceae had 2 species each; Euphorbiaceae, Mimosaceae, Malvaceae, Portulacaceae, Cucurbitaceae, Urticaceae and Commelinaceae all had 1 species each. A total of five families were recorded for grasses while Asteraceae family had four species. The family Poaceae had the highest number, 5 species and the family Cyperaceae had 3 species. From the above results, the families that had the most common herb species were Poaceae, Asteraceae and Cyperaceae. The results also revealed that a good number of plant species showed very high Importance Value Index (IVI) of above 50%. The results of Shannon- Weiner index of Diversity for the study area was higher in site A point 1 at 0-5 cm depth (1.196), site B point 1 at 0-5 cm depth (2.136) and site C point 1 at 0-5 cm depth (2.314). The results of this study portray significant soil seed bank potentials of the study area because it showed a wide range of species diversity and abundance.