Browsing by Author "Isichei, A. O"

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    Floristics and Structure of the Fallow Vegetation in the Ile-Ife Area of Southwestern Nigeria
    (1997) Oke, S. O.; Isichei, A. O
    A study was made of the vegetation of seven fallow plots in Ile-Ife Area of Southwestern Nigeria. The aim is to provide detailed information on the current state of the Secondary Low-land Forest Vegetation and on the various successional stages formed as a result of human activities. Results show that there are differences in species composition of the plots. Young plots (1-5 years old) had fewer woody species and individuals than the secondary forest plots. The secondary forest plot which is the oldest plot, had the highest mean basal area, mean crown area and greater number of trees in the height class ≥7m while the youngest plot had the lowest mean basal area, mean crown area and had no tree in the height class ≥7m. The woody basal and crown area of the plots depend entirely on the density and size of the woody species. The mean aerial cover of herbaceous plant was more than 100% in all the plots except the secondary forest plots where there was no herbaceous plant at all. The differences in species composition could be attributed to level of human activities on the plots. The knowledge of this species composition in the plots (Biological diversity) can be directed at and preserving the plants for both perceived and economic benefits and for their aesthetic value.
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    Fuel Characteristics and Emissions from Biomass Burning and Land-Use Change in Nigeria
    (Kluwer, 1995) Isichei, A. O; Muoghalu, J. I.; Akeredolu, F. A; Afolabi, O. A.
    Nigeria is one of the 13 low-latitude countries that have significant biomass burning activities. Biomass burning occurs in moist savanna, dry forests, and forest plantations. Fires in the forest zone are associated with slash-and-burn agriculture; the areal extent of burning is estimated to be 80% of the natural savanna. In forest plantations, close to 100% of litter is burned. Current estimates of emissions from land-use change are based on a 1976 national study and extrapolations from it. The following non-carbon dioxide (CO,) trace gas emissions were calculated from savanna burning: methane (CH,), 145 gigagrams (Gg); carbon monoxide (CO), 3831 Gg; nitrous oxide (N,O), 2 Gg; and nitrogen oxides (NO,), 49 Gg. Deforestation rates in forests and woodlands are 300 x 103 ha (kilohectare, or kha) and 200 x kha per year, respectively. Trace gas emissions from deforestation were estimated to be 300 Gg CH,. 2.4 Gg N,O. and 24 Gg NO,. CO, emissions from burning, decay of biomass, and long-term emissions from soil totaled 125 561 Gg. These estimates should be viewed as preliminary, because greenhouse gas emission inventories from burning, deforestation, and landuse change require two components: fuel load and emission factors. Fuel load is dependent on the areal extent of various land uses, and the biomass stocking and some of these data in Nigeria are highly uncertain.
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    Nitrogen and Potassium Leaching Off Inselberg Surface Lichens at the University of Ife.
    (Obafemi Awolowo University, 1986) Ekeleme, Friday; Isichei, A. O
    The leaching of nitrogen (nitrate-nitrogen and total nitrogen) and potassium off inselberg surface lichens by rainfall on Hill II, University of Ife campus was studied in the period between 11th March and 15th October, 1985. Rain free-fall, surface flow off lichen surfaces on the inselberg and run off from vegetation mats were collected from permanent collecting points after each shower. The nitrate-nitrogen, total-nitrogen and potassium amounts of free-fall were 1.74, 12.33 and 6.18 kgha-1yr-1 respectively. The inputs of these elements were highest in the early part of the rainy season. The concentrations of nitrate-nitrogen, total-nitrogen and potassium leached off the lichens fluctuated widely without any obvious pattern. This is discussed in relation to lichen physiology. Overall, 3.15 kgha-1yr-1 nitrate-nitrogen, 49.73kgha-1yr-1 total-nitrogen and 30.77kgha-1yr-1 potassium was leached off lichen surfaces. The highest concentration of potassium was leached in the first five showers. A comparison of both the concentrations and leaching patterns of total-nitrogen and nitrate-nitrogen off inselberg surface lichens with that leached off the vegetation mats showed that the amounts of these elements leached off the mats fluctuated as much as that leached off the lichens. The amounts of potassium leached off vegetation mats decreased as the season progressed. An estimated 2.3lkgha-1yr-1 nitrate-nitrogen, 32.73kgha-1yr-1 total-nitrogen and 25.l10kgha-1yr-1 potassium was leached off the vegetation mats. The amounts/quantities of these nutrient elements leached off the lichens were on the average higher than that leached off the mats. The estimated quantities (kgha-1yr-1) of nitrate-nitrogen, total-nitrogen and potassium charged to the environment surrounding the inselberg used for the study were 5.46, 82.46 and 55.87 respectively.