No abstract

A survey was carried out to determine the type of mycorrhizal association formed by trees within the different habitat types of the disturbed and undisturbed sites of the Takamanda rainforest. Forty-eight tree species of commercial and cultural importance were selected from the two sites for this study. Root samples were collected from a total of 327 individual trees belonging to the 48 species; they were cleared, stained and examined microscopically for mycorrhizal colonization and type. All the forty-eight species examined harbored one or more mycorrhizal structures, which ranged from arbuscules, intercellular hyphae, intracellular hyphae, vesicles, and Hartig net. Thirty-nine species formed exclusively arbuscular mycorrhiza (81.25%), two species; Uapaca guineensis and Angylocalyx oligophyllus formed ectomycorrhiza only (4.17%), while seven species Afzelia bipindensis, Baphia nitida, Anglylocalyx pynaertii, Cieba pentandra, Cylicodiscus gabunensis, Pterocarpus soyauxii and Terminalia ivorensis formed both ecto-and arbuscular mycorrhiza (14.58%). In both forest sites and habitat types, arbuscular mycorrhiza was the most represented among the tree species. In the undisturbed site and in the plain 68% of tree species sampled formed arbuscular mycorrhiza, 12% formed ectomycorrhiza, 16% formed dual mycorrhiza and 4% were non-mycorrhiza. On ridge top, 81.8% of the tree species formed arbuscular mycorrhiza, 13.6% formed ectomycorrhiza with 4.6% being dual mycorrhiza. On hilly slopes, 82.8% of the tree species formed arbuscular mycorrhiza, 13.8% formed ectomycorrhiza and 3.5% were dual mycorrhiza. In the disturbed site, 100% of the tree species sampled on the plain, formed arbuscular mycorrhiza. On the ridge top, 73.3% of the tree species sampled formed arbuscular mycorrhiza, 13.3% formed ectomycorrhiza and 13.3% were non mycorrhizal. On hilly slopes, 83.3% formed arbuscular mycorrhiza, 8.3% formed ectomycorrhiza and 8.3% were non-mycorrhizal. Mycorrhizas are important factors in Takamanda and must be taken into consideration, when designing management strategies for this forest.

This study explores the effects of different levels of urea and folivert (composite fertilizer) on seedlings growth and chlorophyll concentration of Albizia zygia, Blighia welwitschii, Lophira alata and Pterocarpus soyauxii. The rate of fertilizer application per 5.87kg pot with topsoil was 3, 6, and 9g of both urea and composite fertilizer and a control (top soil only) and it was a complete randomized design. Results indicated that plants treated with 3g of urea produced the highest number of leaves in Albizia zygia seedlings only while 9g of composite fertilizer had the best growth performance in all the other growth variables.  Albizia zygia and Blighia welwitschii, seedlings had the best results in soil treated with 6g of composite fertilizer, while Lophira alata and Pterocarpus soyauxii seedlings showed best growth in soils treated with 9g of composite fertilizers for all other parameters. Seedlings of species supplied with 9g of urea gave poorest growth performance.  Low root/shoot ratios were obtained for all seedlings except for those of Albizia zygia treated with 6 and 9g of urea that had root/shoot ratios greater than 1.0. The effect of fertilizers on chlorophyll concentration was significantly different only for L. alata (P=0.05). This study therefore brings to light the need to fertilize timber tree seedlings in order to improve on their early growth performances in the field and high doses of nitrogen should be discourage.

Tropical montane forests are considered to be one of the most species diverse ecosystems. These areas pose specific edaphic and environmental characteristics which enable these areas to harbour wide varieties of organisms. Some of these organisms are threatened and others are endemic to the area. The quest for food and other resources has resulted to indiscriminate exploitation of these montane forest. This study aimed to investigate the stand structure, distribution patterns and regeneration status of six tree species (Nuxia congesta, Pittosporum mannii, Podocarpu slatifolius, Prunus africana, Schefflera abyssinica and Syzygium guineense) along altitudinal gradients in the Kilum-Ijim Forest Reserve, Cameroon. A total of six study plots of one hectare (100 x100 m) each were laid across a 120 m elevation gradient. Two plots were established at each altitudinal gradient with elevations 2377 m, 2437 m and 2497 m. Measurements were taken for tree height, diameter at breast height (DBH 1.3 m) for the tree and poles. The digital Vernier callipers were used to measure collar diameters of seedlings and saplings. The highest tree density of 385 stems/ha was recorded for N. congesta at altitude 2497 m while the least was 20 stems/ha for S. abyssinica at altitude 2377m. The highest seedling density was 1563 stems/ha recorded for P. mannii at altitude 2377m and the least was noted for S. abyssinica at all the three altitudinal gradients.  Nuxia congesta had the highest basal area of 8809.23m2/ha at altitude 2437 m and the least of 74.82m2/ha for P. latifolius at altitude 2437 m.  The highest IVI occurred in N. congesta (131.91) was recorded at altitude 2377 m and the least (24.91) occurred in P. latifolius at altitude 2437 m. The spatial distributions of studied tree species were generally clumped and irregular. The regenerations of species were generally poor, though fair regenerations were noticed for N. congesta and P. mannii. The results showed that the six tree species were highly disturbed by anthropogenic activities. It is therefore imperative to develop and implement effective conservation measures to sustain the biodiversity of this reserve.