ABSTRACT

 A 7x 9 factorial experiment iii randomized complete block design with three replications was used to study the effect of time (January July, 2005) on the mineral contents (%) leaves and twigs of the following nine forest tree species, Nauclea diderrichii, Pentaclethra macrophylla, Pterocarpus santalinioides, Trecuia africana, Piptadiniasiruin africanuin, Brachysiegia eunvco,na, Leucaena Ic ucocep ha/a, Daclyladenia barteni and Mi/ic/a excelsa, within the relict forest at Michael Okpara University of Agriculture, Umudike Nigeria. Nauclea diclennichii and L. leucocephala. had similar N contents in their leaves that were significantly higher than those of the other species. The similar N contents in leaves of the species in January and July, 2005 were higher (P< 0.05) than those in February — June, 2005. Leucaena IeucoephaIa 's leaves gave significantly the highest N contents. Leaves of P. rnacrophy//a and N. diderrichii had similar (P 0.05) P contents which were significantly greater than those of the other seven species. June, 2005 gave the highest (P< 0.05) P contents in the leaves of the nine tree species. Pterocarpus santa/mb/des had significantly higher K contents in its leaves than the other eight species. March and April, 2005 gave significantly the highest and least K contents in the leaves of the forest plant species. Leaves of P. african/urn in July, 2005 had the highest (P<0.05) K contents than those of the other tree species, over the study period. Leaves of M. excelsa and P. inacnophvl/a had statistically similar Na contents which were significantly higher than those of the other species. Dactyladenia barteri gave the least (P>< 0.05) Na contents. The Na contents of he tree species in March and April, 2005 were significantly lower than those of the other months. Leaves of P. macrophylla and P. santa/inioic/es had statistically similar Ca contents that were higher (P< 0.05) than those of the other species. In June and July, 2005, leaves of the nine species had higher (P< 0.05) Ca contents than in February — May, 2005. In June, 2005, leaves of P. macnophylla gave the highest Ca contents while in April, N. diderrichii had the least Ca result. Leaves of M. excelsa and T. african had similar Mg contents that were higher (P< 0.05) than those of the other species. The xii highest (P 0.05) Mg contents in the leaves of the nine species were obtained in May and July, 2005 while March 2005 had the least Mg value. Leaves of B. eurycoma gave significantly the highest Mg content in April, 2005. M .excelsa and B. eurycolna, with similar results, had statistically the highest N contents in their twigs. In April 2005, the N contents in the twigs of the nine species were significantly higher than those of January, February, March — July, 2005. In April, 2006, P. macrophylla had the highest (P< 0.05) N contents in its twigs. The statistically similar P contents in twigs of P. macrophylla and L. leucocephala were significantly higher than those of the other species. March and April, 2005 had similar P contents in twig of the nine species which were higher (P< 0.05) than those of the other study periods. The similar K contents of twigs of L. leucocephala and T africana, were statistically higher than those of the other species. Twigs of January and April, 2005 had similar K values which were significantly higher than those of the other study periods. The K contents of twigs of the nine species increased from Januaiy — May, 2005, decreased between May and June, 2005 and, increased again in July, 2005. Twigs of L. leucocephala and P. santalinioides gave significantly the highest and least Na contents. In January and July, 2005, twigs of L. leucocephala had significantly the highest Na contents. Twigs of P. macrophylla had the highest (P < 0.05) Ca contents. February and June, 2005 had significantly the highest and least Ca contents in the twigs of the tree species. Twigs of Leucaena leucocephala and B. eurycoina had statistically the highest and least Mg contents. The similar (P < 0.05) Mg contents in twigs of the nine species in February and July, 2005 were significantly higher than those of the other study periods.