Nutrient uptake of Archidium acanthophyllum and Cyanotis lanata from Savanna Microsites on Baasi Inselberg in Southwestern Nigeria

Nutrient concentrations and their mobility between soil and two dominant plants, moss (Archidium acanthophyllum Snider. (Archidiaceae) and succulent monocot (Cyanotis lanata Benth. Commelinaceae) growing on Baasi -Inselberg was investigated over a period of 36 months. The surface of the inselberg was divided into four microsites (Ms). Ms-1, bare soil; Ms-2, A. acanthophyllum only; Ms-3, C. lanata only; Ms-4, both Ms-2 and Ms-3. Samples of soil and plants were taken from one quadrat (0.5 m x 0.5 m) in each microsite for analysis of their ion contents. Plant debris, dust and rain water formed the primary sources of nutrients on the inselberg. Early rainfall (in April) triggered the growth of A. acanthophyllum which peaked in May and sharply decreased in June. Thereafter growth rate increased gradually from June to December (early dry season) and remained constant between January and March. In the early rainy season and early dry season, nutrient 2+ -1 + -1 2+ -1 + -1concentrations were higher (Ca , 1500 µgg ; K , 150 µg g ;Mg , 100 µg g ;Na , 30 µg g ) than other months of the seasons. In Ms-4 there was a higher resultant sequestration of ions in the plant tissues + -1 2+ -1 2+ -1 + -1 + (K , 800 µgg ;Ca , 600 µgg ; Mg , 160 µgg ;Na , 28 µgg ). The Ms-1 was the source of Na + 2+ 2+concentration in Ms-4, for K Ms-2 and Ms-3, for Mg Ms-2 only and for Ca Ms-1, 2 and 3.