DSpace Angular :: Browsing by Author "Isichei, A. O."

Browsing by Author "Isichei, A. O."

Now showing 1 - 20 of 28

Open Access
African Greenhouse Gas Emission Inventories and Mitigation Options: Forestry, Land-Use Change, and Agriculture
(Kluwer, 1995) Braatz, B. V.; Brown, S.; Isichei, A. O.; Odada, E. O.; Scholes, R. J.; Sokona, Y.; Drichi, P.; Gastonz, G.; Delmas, R.; Holmes, R.; Amous, S.; Muyungi, R. S.; De Jode, A.; Gibbs, M.
Human-induced change in the composition of the atmosphere seriously threatens the global climate. In an effort to address this threat, 161 nations signed the United Nations Framework Convention on Climate Change at the Earth Summit in Rio de Janeiro in June 1992. The ultimate objective of this international agreement is to achieve stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. As of the first session of the Conference of the Parties (March/April 1995), 128 nations had ratified the Convention. Parties to the Convention commit to numerous obligations, including commitments to: develop national inventories of anthropogenic emission using agreed, comparable methodologies; and to formulate and implement national programs containing measures to mitigate, and to facilitate adaptation to, climate change. Several bilateral and multilateral programs, including the United States Country Studies Program (U.S. CSP) and the United Nations Environment Programme/Global Environment Facility Country Case Studies Project (UNEP) have been established to provide technical and financial assistance to developing countries and countries with economies in transition in meeting their commitments under the Convention.
Open Access
Characterization of the Forest Types of the University of Ife Campus.
(Obafemi Awolowo University, 1986) Chukwuka, Kanayo Stephen; Isichei, A. O.
The rainforest in the University of Ife was characterized by species enumeration and girth measurements, and by attributes derived from these measurements in 17 sample plots. The seventeen plots were located around one of the three hills on the campus, Hill 1, a general uniformity in species composition was observed for all the plots studied with the exception of those on the hill top where Brachystegia eurycoma was found to be dominant and, at times slopes which differed in species composition. The Shannon-Weiner species diversity index for all the plots was in the range 1.88-3.36. Dominance by Manihot glaziovii and Funtumia elastics were, however, observed in two plots. Plots ordination based on species showed plots on the hill top and slopes to be floristically different from those on the flat and gentle surfaces, while the species attributes ordination based on the plots showed that species diversity index, and basal area of species were more important in characterizing the sample plots. The stem girth distribution was generally found in the 11-20cm girth class with the exception of three plots. Two of the plots have high number of big trees in the > 120cm girth class while one has the highest number of stems in the 21-30cm girth class. These observations were discussed in relation to past land use in the area. The nature of succession of these plots was assessed by a modification of Horn's (1975) Markovian change. The application of this model was, however, found not to be satisfactory in assessing the succession of the sampled plots because it showed that regrowth species such as Microdesmis puberula and Napoleons vogelii will form the next generation canopy.
Open Access
Ecology and Biology of Piliostigma Thonningii (Schum.) Milne-Redhead in the Guinea Savanna Zone of Nigeria.
(Obafemi Awolowo University, 1985) Mbaekwe, Ebenezer Ike; Isichei, A. O.; Sanford, W. W.
Eighteen plots in selected sites from the Mokwa, Kainji and Yelwa areas of the Nigerian Guinea savanna were sampled systematically for vegetation attributes. Four belt transects in each plot were sampled to estimate the density of all woody individuals greater than 1m high, density of Piliostigma thonningii, total basal area of woody species, and woody plant cover. Soil samples were randomly collected from the 0-15cm depth in the plots and analysed for texture organic matter and nitrogen. The vegetation and soil data and attributes derived from them were used for ordinations using principal components analysis. The ordinations show that soil factors namely sand: clay ratio organic matter and nitrogen content were, in association with some vegetation attributes, important in determining the distribution and density of P. thonningii in the areas studied. Some aspects of the biology of the plant were also studied. Best germination results were obtained after acid treatment. The phenology of the plant and its response to perturbations were observed and these observations gave an insight into its mode of propagation. Anatomical studies showed the leaf characters as being semi-xerophytes and the stem as having growth rings. The age of the plant could be estimated from ring counts. Examination of the plant for nodules did not yield positive results but nitrogen levels in the leaves compared favourably with those of other browse plants in the same area. This identifies the plant as an important browse species in the savanna. Overall, the study has highlighted the conditions under which the plant grows and its rich potential as a source of cover and browse in the Guinea savanna.
Open Access
Ecology of Piliostigma Thonningii in Early Successional Plot in Northwestern Nigeria
(1990) Mbaekwe, E. I.; Isichei, A. O.
In the Kainji Basin, Mokwa and Yelwa areas of northwestern Nigeria early successional plots are usually dominated in terms of number of stems by the Caesalpinioid shrub Piliostigma thonningii. An ecological study of 17 sample plots from the areas was carried out in order to define the niche of Piliostigma because of its potential in providing soil cover and rehabilitation of degraded lands. In the plots studied it was found that Piliostigma abundance was associated with a high soil sand: clay ratio, open vegetation canopy and low species diversity. These characteristics identify Piliostigma as an early successful species.
Open Access
Effect of Soil Texture, Nutrient Stress and Water Stress on Yield of Andropogon Gayanus Kunth and Schizachyrium Sanguineum (Retz.) Alston.
(Obafemi Awolowo University, 1985) Oke, Samson Olajide; Isichei, A. O.
Two grasses, Andropogon gayanus and Schizachyrium sanguineum grown to maturity in fine and coarse sand culture were subjected to nitrogen and water stresses to study how these stresses interact with soil texture in affecting growth and nitrogen accumulation in these grasses. Nutrient-stressing involved administering 200m1 of a nutrient solution containing. 35 parts per million nitrogen once in four days while for water-stressing the same volume of water was fed to the plants at the same frequency. These treatments, if administered once in two days, were considered adequate for the plants. There were two other intermediate treatments. Plants grown in fine sand produced more dry matter the highest yield was adequate nitrogen and water stressing while nutrient and water stressing gave the lowest. The biomass of the two grasses increased with increased nutrient addition to the growth medium. Nutrient stress had a more noticeable effect in reducing yield than water stress. Plants grown in coarse sand had a higher nitrogen concentration than those grown in fine sand. This is attributable to high organic matter content of fine sand the highest yield was adequate nitrogen and water stressing while nutrient and water stressing gave the lowest. The biomass of the two grasses increased with increased nutrient addition to the growth medium. Nutrient stress had a more noticeable effect in reducing yield than water stress. Plants grown in coarse sand had a higher nitrogen concentration than those grown in fine sand. This is attributable to high organic matter content of fine sand grown grasses which led to dilution of nitrogen concentration. In absolute terms, plants grown in fine sand had more nitrogen content. Increasing frequency of nitrogen addition resulted in higher nitrogen content of the grasses. As with yield, giving adequate nitrogen and water-stressing resulted in the highest nitrogen accumulation while water and nutrient stressing gave the lowest. Schizachyrium sanguineum accumulated more nitrogen than Andropogon gayanus because it is more efficient in utilizing nutrients in a low concentration medium. As for plant parts more nitrogen was accumulated in the roots than leaves or stems. The implications of these observations in relation to the natural conditions in which these grasses grow are discussed.
Open Access
Effect of tree canopy cover on the yield, crude protein and fibre content of forb species in Nigerian Guinea savanna
(Kluwer, 1991) Muoghalu, J. I.; Isichei, A. O.
The relationship between tree canopy cover and forb species in savanna was investigated by examining the effect of tree canopy cover on the yield, crude protein, fibre and lignin content of forb species. The yield of some forb species show a tendency of being higher under tree canopy than in the open though no statistical significance can be shown. A higher forb yield is obtained under high tree canopies than under lower ones. No significant differences in mean crude protein, fibre and lignin content were observed between forb species growing under tree canopy and those in the open.
Open Access
The Effects of Ground Fire on Tree Population in a Secondary Forest in South Western Nigeria
(1998) Kayode, J.; Isichei, A. O.
The changes in the tree population in a 50m x 50m rain forest plot on the campus of Obafemi Awolowo University, Ile-Ife, Nigeria, six years after it was burnt were assessed by comparing the results obtained in 1989 with those of January 1983, just before the plot was burnt and those of April 1984, a year after the plot was burnt. The number of tree species and the numbers of tree individuals had increased between 1984 and 1989 by 10%. Manihot glaziovii Mill-Arg the most abundant species in the plot in 1984 still maintain its status but its density decreased from 81% in 1984 to 61% in 1989 while Funtumia elastica (Preuss) stapf showed a remarkable increase from 8% in 1984 to 88% in 1989. Other species present in the plot showed a little net change in population over the same period. These observations demonstrated successional trend in gap replacement. It is considered that population dynamics is better studied by monitoring plot over time as the best was of studying plant succession.
Open Access
Effects of Oil Industry Operations on Vegetation in Nigeria
(Seems, 2014) Isichei, A. O.
The prospecting, exploration, development and production of oil and gas resources follow a sequence of steps that each affects vegetation in different ways. First, geological and geophysical studies are conducted over large areas to identify favourable exploration targets. This is followed by more intensive study, testing and drilling in selected areas to locate and evaluate the oil and gas resource. Production facilities include wells and pumps, gathering and transportation lines, storage tanks and some primary processing facilities.
Open Access
The Estimation of Age and Analyses of the Growth Rate Piliostigma thonningii (Schum.) Milne-Redhead in the Guinea Savanna Zone of Nigeria
(2007) Isichei, A. O.; Mbaekwe, E. I.
Estimates of age and analyses of growth rate of Piliostigma thonningii were made by counting rings and measuring ring widths in those plants that formed distinct rings. In the others, with indistinct rings or no rings, the regression method was used to estimate the ages, using known ages and girths to derive a regression equation. There was a high correlation coefficient between age and girth (r = 0.96), less so between age and mean annual growth increment (r = 0.71) and much less so between age and bark thickness (r = 0.54). The estimated mean annual growth increment (cm) for all the tress sampled was 1.07 ± 0.23 (at 95% confidence limit).
Open Access
Floristics and Structure of the Remnant Forests of the Obafemi Awolowo University Campus, Ile-Ife Nigeria and their Potential for Conservation
(1997) Chukwuka, K.; Isichei, A. O.
The floristic composition and the girth sizes of the woody plants in seventeen sample forest plots at the Obafemi Awolowo University, Ile-Ife, Nigeria were studied with a view to making recommendations on the conservation of the forest. The 120 species found are those typical of drier lowland forest of southern Nigeria. Twenty-six species occurred in 8 of the 17 plots while 28 occurred in one plot each and could be regarded as rare. About 70% of the stems are less than 30cm girth at breast height, an indication of recent disturbance. Brachystegia euryoma dominated the ≥120cm girth class and was found on hilly slopes that were unsuitable for farming. The benefits of conservation of the Campus forest include protection of an important watershed and teaching and research.
Open Access
Impact of Land Use on Biodiversity in the Savanna Zone of West Africa
(Unesco, 1995) Isichei, A. O.
Biodiversity is a very important aspect of the natural resources of West African savanna and it is affected by land use. Savanna has traditionally been used for animal husbandry but with the shortage of agricultural land in moist zones, large-scale crop agriculture is being intensified in all the savanna zones. Agricultural expansion and intensification have resulted in reduction of crop diversity and encroached on conservation areas. Conservation efforts through the system of reservation have not been vigorous and current trends of loss of biodiversity will continue unless alternatives to Reserves are found. The Biosphere Reserves Concept initiated by UNESCO offer means of utilizing natural resources in a sustainable manner. The Concept is discussed in relation to the problem of biodiversity conservation in West Africa.
Open Access
Impact of Overgrazing on Agricultural and Rangelands
(Unesco, 1993) Isichei, A. O.
Herbivory is the consumption of living plant tissues by herbivores and the term includes grazing, browsing, defloration, seed predation, parasitism and disease (Louda et a/., 1990). Grazing is used in the same sense as herbivory in popular literature but is usually restricted to consumption of living herbage by ruminant livestock. The present report deals with the relationship between the grazing animals and their environment. Practically all vegetation types have grazing animals in them but what matters is the concentration of animals and the corresponding intensity of grazing. The suitability of the vegetation type for providing readily accessible forage and climatic and other related constraints, including landuse economics and pests affect animal abundance. Generally, forest vegetation unless specially converted is not suitable as grazing land and could be more profitably used for cultivation. Most grazing lands are for the above reasons concentrated in subhumid, semi-arid and arid ecologies especially in the tropics. Such lands are also referred to as ragelands and at times in a restricted sense, pastures.
Open Access
Nitrogen Fixation by Blue-Green Algal Soil Crusts in Nigerian Savanna
(1980) Isichei, A. O.
Blue-green algae, many of which are known to be nitrogen fixers, occur on the surface of the soil as crusts. Crusts are masses of algal filaments that grow on top of each other. These blue-green algal crusts were collected from all of the savanna zones of Nigeria in order to estimate the quantitative role they may play in the nitrogen economy of savanna ecosystems. Algae of the genus Scytonema, which are nitrogen fixers, were dominant in all the crust samples collected. Using the acetylene reduction assay, it was found that the crust samples fixed nitrogen 24 h after rewetting and were affected by pH, temperature, light and moisture variations. If sufficient light were available for near maximum photosynthesis, with an algal cover of the soil surface of about 30 % and mean to maximum-fixation during 70 %of the rainy season of 180 days of 10-hour day-length, from 3.3 to 9.2 kg ha-' yr-' of nitrogen would be fixed. This amount would replace much of the nitrogen lost from the grass standing crop as a result of annual burning of the savanna.
Open Access
Nitrogen Fixation by Soil Algae of Temperate and Tropical Soils
(Plenum Press, 1977) Stewart, W. D. P; Sampaio, M. J.; Isichei, A. O.; Slvester-Bradley, R.
Blue-green algae are common components of the microbial flora of the soil in many parts of the world (7, 8, 18, 30). In the tropics most attention has been paid to their role in rice paddy soils where, free-living (26, 27) and in symbiotic association with the water-fern Azolla (3, 19, 21, 36) they contribute substantial amounts of nitrogen to the ecosystem. In this paper we present information on the occurrence, activity, and factors affecting soil algae from tropical savanna regions of Nigeria and from the Amazon region of Brazil. The findings are compared with observations made on algae from temperate soils in Scotland. These studies complement ones from tropical (e. g. 22, 26, 27, 37) and temperate (e.g. 6, 9, 12, 28) regions.
Open Access
Nitrogen Loss by Burning from Nigerian Grassland Ecosystems
(Royal Swedish Academy of Sciences, 1980) Isichei, A. O.; Sanford, W. W.; Rosswall, T.
Nitrogen loss by burning from natural grassland ecosystems in Western Nigeria was studied over a two-year period in three areas, including sites of Andropogon-Hyparrhenia - Schizachyrium-Brachiaria grassland in derived, Southern Guinea and Northern Guinea savanna. The production of aboveground herbaceous material and litter fall of leaves, wood and fruit/seed was estimated and the nitrogen content just prior to burning determined. Final estimates of from 12 to 15 kg ha-1 yr-1 of nitrogen lost by burning were obtained. it is suggested that such loss may be replaced to a considerable extent by rain and blue-green algal crust fixation.
Open Access
Nutrient Status of the Leaves of Piliostigma Thonningii (Schum.) Milne-Redhead in the Guinea Savanna Zone of Nigeria
(2006) Mbaekwe, E. I.; Isichei, A. O.
The value of Piliostigma Thonningii as a browse plant in the Guinea Savanna Zone of Nigeria was assessed by analysing its leaves for nitrogen, phosphorus, potassium and carbohydrate contents. Sampling of the leaves was done from five different plots, at two different growth periods, that is March/April and October/November, representing the beginning of flush and the peak of vegetative growth respectively, and on both the apex and base of the twigs. Higher values for % total nitrogen, extractable potassium and % soluble sugar and starch were obtained at the beginning of flush when the leaves were younger than at the end when they were much older, indicating a decline of these essential nutrient elements with the age of the leaves. This trend was found to be statistically significant. The % total phosphorus was low, probably reflecting the reported low values for this essential element in Savanna soils. The nitrogen content compares very well with those of other species in the Savanna and is even higher than those of grasses at equivalent sampling period (October - November), indicating the importance of the leaves of P. thonningii as a source of browse for both wildlife and livestock at a critical period in the Guinea Savanna.
Open Access
A population viability analysis of serendipity berry (Dioscoreophyllum cumminsii) in a semi-deciduous forest in Nigeria
(Elsevier B.V., 2006) Obioh (nee G.U. Ahuama), G. I. B.; Isichei, A. O.
The search for natural sweeteners has prompted intensive research on plants with sweetening properties. Dioscoreophyllum cumminsii (Stapf) Diels is a dioecious, semelparous annual liana found as a late successional, understorey species in West Ahican semi-deciduous forests. The fruits and subterranean tubers are intensely sweet and are both edible. The sweetening substance in D. cumminsii is a protein (monellin), which is 3000 times as sweet as sugar. Unfortunately, it is one of the threatened plant species in the country because of massive habitat loss and fragmentation. Conservation is now needed as a salvage programme. Population size is a major determinant of extinction risk. This has prompted the application of growth and population dynamics models to viability analysis of wild species. The aim of population viability analysis (WA) is to determine the minimum viable population size (MVP) or area (MVA) of a particular species. In this paper, MVP was estimated for D. cumminsii using genetic models. The models simulated minimum effective population size of 6040individualsha-I in the ratio of 5032 males to 1008 females. This suggests that to retain evolutionary potential, D. cumminsii requires an effective population size of more than the SOCL5000 range considered adequate for many other species.
Open Access
The Potential of Algae in Agriculture, Environmental Conservation and Industry in Nigeria
(1993) Isichei, A. O.; Okusami, V. B.
Algae occur as surface crusts, as free living organisms in water bodies and in symbiotic association with fungi in lichens. Algae occurring in these forms have potential roles in physical improvement and protection of soils, in nitrogen fixation in paddy rice cultivation and arid agriculture, in primary biomass production and in secondary production for industrial uses. They also play useful roles in reclamation and purification of polluted waters. These potentials are discussed with special reference to Nigeria. It is argued that algae as plants may not be 'lost' to Nigeria but that their yet unexploited potentials need to be fully investigated.
Open Access
The Reversibility of Changes in Species Composition, Production and Soil Properties Following Defoliation, Trampling and Application of Excreta
(RSSD Australia, 1988) Isichei, A. O.; Walker, Brian H.; Menaut, Jean-Claude
An important notion underlying the experimental hypotheses is that it is not the direct effects of herbivory on the vegetation, but rather the indirect effects on soil properties which increase the irreversibility of changes to vegetation properties.
Open Access
The Role of Plant Resources in Nigeria's Economic Recovery Agenda
(2005) Isichei, A. O.
Basically, it is the performance of plants and chemical composition that we exploit for economic and cultural purposes. Our human world has been so closely tied to plants that it is difficult to imagine human existence without them. In all life on earth, plants are the only producers and all consumers are dependent upon plants for food, fibre, wood, energy and oxygen. Knowledge of plants, their habitats. structure, metabolism and inheritance is thus the basic foundation for human survival. Plants form the bedrock of life, being the first generator of oxygen in a reducing atmosphere that characterized the early earth. Plants are thus the roots of life and human material culture depends on them. The way a people incorporate plants into their cultural traditions, religions and even cosmologies reveals much about the people themselves. People rely on plants for much more than food and shelter and people use plants in so many ways that there are a few areas of human endeavour in which they do not play an important role. Plants have determined the course of human civilization - America was discovered during the course of the search of spices. Few societies can ignore the pivotal role of agriculture and forestry, both based essentially on plants. Several environmental crises such as global warming and biodiversity loss at their core, involve plants. It could indeed be that we are so closely linked that humans often take plants for granted, something to be left to the background and not worthy of serious economic consideration. But we met plants on our planet and they have defined our 'life zones'. The late appearance of humans on the evolutionary scene laid open to us a large variety of natural resources to exploit for food and plants were the natural choice, being the only organisms that had the capability to convert solar energy to chemical energy. From them we have learnt about life and it now looks as if we still have to depend on them to sort out our environmental crisis.