ABSTRACT

A 7x 9 factorial experiment in randomized complete block design with three replications was used to study the effect ol time (January — July, 2005) on the mineral contents (%) leaves and twigs of the following nine forest tree species, Nauclea diderrichii, Pentaclethra macrophylla, Pterocarpus santalinioides, Trectdia africana, Piptadiniastrum africanum, Brachystegia eurycoma, Leucaena leucocephala, Dactyladenia barteri and Milicia excelsa, within the relict forest at Michael Okpara University ol Agriculture, Umudike Nigeria. Nauclea diderrichii 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 leucocephala's leaves gave significantly the highest N contents. Leaves of P. macrophylla 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 santalinioides 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. africanium 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. macrophylla 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. santalinioides 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. macrophylla gave the highest Ca contents while in April, N. diderrichii had the least Ca result. Leaves ofM. excelsa and T. africana had similar Mg contents that were higher (P< 0.05) than those of the other species. The 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. eurycoma, with similar results, had statistically the highest N contents in their twigs. In April 2005, the N contents in the twigs ot the nine species were significantly higher than those ofJanuary, 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 ofthe 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. Icucoccphala and T. africana, were statistically higher than those of the other species. Twigs ofJanuary 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 ncreased from January - 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. Icucoccphala had significantly the highest Na contents. Twigs ofP. 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. eurycoma 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 ofthe other study periods