ONYEKWELU JONATHAN C. picture
ONYEKWELU JONATHAN C.

Publication

Publisher:
 Environment And Ecology Research 4(4): 185-192,
Publication Type:
 Journal
Publication Title:
 Assessment Of Urban Forest Tree Species Population And Diversity In Ibadan, Nigeria.
Publication Authors:
 Agbelade, A.D., Onyekwelu, J.C. And Apogbona, O.
Year Published:
 2016
Abstract:
This research focuses on the urban tree species population and diversity within Ibadan metropolis as a means of creating biodiversity database for the urban centre in South west, Nigeria. This was determined by assessing urban forest tree abundance, species diversity and growth yield. All trees with diameter at breast height (dbh) ? 10 cm were identified, dbh measured and their frequencies taken in all the area enumerated within Ibadan. There are 155 tree stems belonging to 26 families and 54 tree species within Ibadan built-up areas and 101 tree stems belonging to 16 families and 19 tree species in peri-urban centre of Ibadan. The two most abundant species and families were Delonix regia of Fabaceae family and Terminalia ivorensis of Combretaceae family (18 and 17 stems) respectively while Fabaceae family has (7 species). The value of the Shannon’s max diversity index (Hmax) of (3.99 and 2.94), Shannon-Wiener diversity index (3.35 and 2.48) and species evenness 0.84 were the same for peri-urban centre, while the growth variable were basal area and volume of (22.8m2 and 18.5m2) and (284.8m3 and 275.3m3) respectively. This study provide information on the level of tree species biodiversity due to infrastructure development that has reduced forest cover within the built-up areas of Ibadan which can expose the city to lot of environmental hazard. 
Publisher:
 Journal Of Forestry Research, 26:417-424
Publication Type:
 Journal
Publication Title:
 Antioxidant, Nutritional And Anti-nutritional Composition Of Garcinia Kola And Chrysophyllum Albidum From Rainforest Ecosystem Of Ondo State, Nigeria
Publication Authors:
 Onyekwelu, J.C., Oyewale, O., Stimm, B. And Mosandl, R.
Year Published:
 2015
Abstract:
Tropical forests contain many tree species that have supplied edible fruits for centuries. These fruits have contributed to human diets due to their richness in nutrients, vitamins, minerals, antioxidants and their low antinutrients content. We investigated the antioxidant, nutritional and anti-nutritional composition of Garcinia kola and Chrysophyllum albidum fruit parts. The nutritional, anti-nutritional and antioxidant compositions differed depending on the fruit part. Irrespective of fruit part, moisture content was high (72–93 %). While the edible part (fruit pulp) of C. albidum proved a better source of protein (4), fibre (17 %) and fat (2 %), the seed kernel was a better source of ash (2 %) and carbohydrate (15 %). Carbohydrate (22 %), protein (2 %), fat (1 %) and fibre (3 %) were higher in G. kola seed kernel (edible part) than in the pulp and pod. Anti-nutrient content in G. kola and C. albidum fruits was low, indicating that their consumption would not pose nutritional or health problems. The antioxidant compositions (especially phenolic content (10–21 mgg-1) and DPPH (1,1-diphenyl–2 picrylhydrazyl) (26–55 %)) of C. albidum fruit pulp and G. kola seed kernel were high, implying that they could be good sources of natural antioxidants and could be used as supplements in food manufacturing. 
Publisher:
 Journal Of Tropical Forest Science, 26(1): 5–15
Publication Type:
 Journal
Publication Title:
 Role Of Sacred Grove In In-situ Biodiversity Conservation In Rainforest Zone Of South-western Nigeria
Publication Authors:
 Onyekwelu, J.C. And Olusola, J.A.
Year Published:
 2014
Abstract:
Though sacred groves were established for spiritual purposes, they are contributing to in-situ biodiversity conservation. The role of groves in biodiversity conservation in south-western Nigeria was investigated in Osun-Osogbo and Igbo-Olodumare sacred groves and compared with degraded and primary forests. All trees (diameter at breast height (dbh) ? 10 cm) were identified and their dbh values measured in each of the 48 temporary sample plots of 20 m × 40 m. Tree seedlings were assessed within 5 m × 10 m quadrat. Osun-Osogbo grove had the highest species abundance (61), diversity index (3.54), number of seedlings (66 species), species evenness (0.66) and percentage of endangered tree species (32.6%) which indicated its importance in in-situ biodiversity conservation. The lower diversity indices of Igbo-Olodumare grove is attributed to its rockiness and low-sacredness, which has led to encroachment. Sacred groves were preserved by fear of deity, cultural importance and place of worship. Benefits derived from groves by the community included healing, protection, tourism and employment. Tree felling within groves was regarded as abomination and sacrifices must be offered before any tree was felled. The rules and taboos used to preserve/protect the groves are crumbling, which must be addressed if they are to continue playing important role in in-situ biodiversity conservation. 
Publisher:
 Global Environmental Change 23: 1064–1072
Publication Type:
 Journal
Publication Title:
 Food Production And Climate Protection – What Abandoned Lands Can Do To Preserve Natural Forests
Publication Authors:
 Knoke, T., Calvas, B., Moreno, S.O., Onyekwelu, J.C. And Griess, V.C.
Year Published:
 2014
Abstract:
Approaches to reconciling food production with climatic and environmental protection often require agricultural intensification. The production of more food per unit of agricultural land through ‘‘sustainable intensification’’ is intended to enable the protection of natural ecosystems elsewhere (land sparing). However, there are problems associated with agricultural intensification; such as soil erosion, eutrophication or pollution of water bodies with chemicals, landscape homogenization and loss of biodiversity; for which solutions have not yet been found. Reuse of abandoned agricultural lands – which are abundant throughout the world – to address the rising demand for food is a potentially important alternative, which up to now has been widely ignored. To test the power of this alternative, equilibrium economic land allocation to various land-use practices by risk-avoiding tropical farmers in Ecuador was simulated. The reestablishment of pastures on abandoned cattle lands lowered prices for pasture products, and also triggered conversion of existing pasture into cropland. The resulting land-use change increased total annual food production in a moderate scenario from the current level of 17.8–23.1 petacalories (1015 calories), which amounted to a production increase of 30%. At the same time, there was a 19% reduction in the amount of payments to farmers required to preserve tropical forests – one of the world’s greatest terrestrial carbon stores. 
Publisher:
 Forests, Trees And Livelihoods; 24 (1): 27–42
Publication Type:
 Journal
Publication Title:
 Farm-level Tree Growth Characteristics, Fruit Phenotypic Variation And Market Potential Assessment Of Three Socioeconomically Important Forest Fruit Tree Species.
Publication Authors:
 Onyekwelu, J.C., Olusola, J.A., Stimm, B., Mosandl, R. And Agbelade, D.A.
Year Published:
 2014
Abstract:
Tropical forests contain many nutritionally and socio-economically important fruit tree species. Farm-level tree growth characteristics, fruit phenotype and market potentials of Chrysophyllum albidum, Irvingia gabonensis and Garcinia kola in rainforest and derived savanna ecosystems of Nigeria were assessed. Growth measurements were made on 100 trees of each species from 10 villages. Questionnaires were used to obtain information from farmers and marketers of the species at farm-gate, urban and rural markets. Mean tree age varied from 19.5 to 43.5 years, with trees in rainforest being older than those in derived savanna. Between 40% and 80% of the species in derived savanna were planted by farmers, whereas only 2–6% of the species were planted in rainforest. C. albidum and I. gabonensis trees in rainforest were significantly older, taller and larger with deeper crowns than those in derived savanna. Although farming of fruit trees is male dominated (76.2–92.3%), marketing of their products is female dominated (60–100%). Annual income from sale of the species ranged from 300 to 1300 US$, with income lowest and highest at farm-gate (farmers) and urban market (traders), respectively. The income contributes 20–60% to annual family income. The old age of most of the trees and the high income derived from their products underscores the necessity for domestication, which should be farmer driven. 
Publisher:
 Journal Of Forestry Research, 23: 253 – 260
Publication Type:
 Journal
Publication Title:
 Soil Microbial Biomass And Population In Response To Seasonal Variation And Age In Gmelina Arborea Plantations
Publication Authors:
 Onyekwelu, J.C.
Year Published:
 2012
Abstract:
We investigated the Effects of plantation development, seasons, and soil depth on soil microbial indices in Gmelina arborea plantations in south-western Nigeria. Soil samples were obtained from the soil depths of 0–15 and 15–30 cm from plantations of six different ages during the rainy season, dry seasons, and their transitions. We used plate count and fumigation-extraction methods to determine microbe population and microbial biomass carbon (MB-C) and nitrogen (MB-N), respectively. Plantation age did not affect microbial indices, implying a non-significant effect of plantation development on microbial communities. It could also imply that soil microbial indices had already stabilized in the sampled plantations. Seasonal variation and soil depth had significant effects on microbial indices. At 0–15 cm soil depth, mean MB-C increased from 50.74 ?g g?1 during the peak of the dry season (i.e. March) to 99.58 ?g g?1 during the peak of the rainy season (i.e. September), while it increased from 36.22 ?g g?1 to 75.31 ?g g?1 at 15–30 cm soil depth between the same seasonal periods. Bacteria populations and MB-N showed similar increasing trends. Correlations between MB-C, MB-N, microbe populations, and rainfall were positive and linear. Significantly higher microbial activities took place in the plantations during the rainy season, increased with soil wetness, and decreased at greater soil depth. 
Publisher:
 Applied Tropical Agriculture, 22 (2): 118-125
Publication Type:
 Journal
Publication Title:
 Biodiversity, Socio-Economic And Cultural Importance Of Trees In Emerging Nigerian Urban Centres: Case Study Of Akure City, Nigeria
Publication Authors:
 Onyekwelu, J.C.
Year Published:
 2017
Abstract:
Recent awareness of the importance of trees have led to their increasing integration in cities. The biodiversity, socioeconomic and cultural importance of trees in Akure city, Nigeria was investigated. Akure was stratified into modern (urban) and ancient (peri-urban); secondary and higher institution sections. The population of Akure is 387,087 inhabitants. A total of 66 tree species were identified in Akure; with 45 and 21 species occurring in modern and ancient sections, respectively. Within the modern section, species with high relative dominance were Caryota spp (28.7) and Polyathia longifolia (23.2) while Carica papaya (14.2) and Mangifera indica (12.9) dominated the ancient section of the city. Secondary schools were dominated by Gmelina arborea (21.4) and Elaeis guinensis (15.2). The dominant species in higher institutions were Terminalia catapa (19.2) and Cocos nucifera (18.1). The socio-economic importance of trees, which depended on the social and educational status of inhabitants, were: ornamental (38%), food/cash crop (36%), timber (11%), shade (9%), life-fence (3%), medicine (3%), cultural purposes (1%). In higher institutions, ornamental (52%) and shade (17%) were the most important uses of trees while in secondary schools, edible fruits (35%) and shade (19%) were important. In the ancient section, food/cash crop was the overwhelming (77%) use of trees while ornamental (90%) was the dominant use in modern section. Most inhabitants in the ancient section sold some of their tree products for income. Some trees served dual purposes depending on the social status of their owners. While T. catapa and M. indica were mostly used for food/cash crop by inhabitants of ancient section, they were used for shade in the modern section. Although medicinal purpose is not currently among the dominant uses of trees in Akure, there are indications that number of people using tree parts for this purpose is increasing. While the poor use trees for food and income in Nigerian emerging cities, the rich use them for ornamental purpose. 
Publisher:
 International Journal Of Forestry Research, Volume 2017, 12pp
Publication Type:
 Journal
Publication Title:
 Tree Species Richness, Diversity, And Vegetation Index For Federal Capital Territory, Abuja, Nigeria.
Publication Authors:
 Agbelade, A.D., Onyekwelu, J.C. And Oyun, M.B.
Year Published:
 2017
Abstract:
This study was conducted to investigate the tree species richness and diversity of urban and periurban areas of the Federal Capital Territory (FCT),Abuja,Nigeria, and produceNormalized DifferenceVegetation Index (NDVI) for the territory.Datawere collected from urban (Abuja city) and periurban (Lugbe) areas of the FCT using both semistructured questionnaire and inventory of tree species within green areas. In the study location, all trees with diameter at breast height (dbh) ? 10 cm were identified; their dbh was measured and frequency was taken.The NDVI was calculated in ArcGIS 10.3 environment using standard formula. A cumulative total of twenty-nine (29) families were encountered within the FCT, with 27 occurring in Abuja city (urban centre) and 12 in Lugbe (periurban centre) of the FCT. The results of Shannon-Wiener diversity index (????????) for the two centres are 3.56 and 2.24 while Shannon’s maximum diversity index (???? max ) is 6.54 (Abuja city) and 5.36 (Lugbe) for the urban (Abuja city) and periurban (Lugbe) areas of the Federal Capital Territory (FCT). The result of tree species evenness (Shannon’s equitability (???? ???? ) index) in urban and periurban centres was 0.54 and 0.42, respectively.The study provided baseline information on urban and periurban forests in the FCT of Nigeria, which can be used for the development of tree species database of the territory. 
Publisher:
 Journal Of Research In Forestry, Wildlife & Environment Vol. 8(4): 1 – 9
Publication Type:
 Journal
Publication Title:
 Predictive Models Of Forest Logging Residues Of Triplochiton Scleroxylon In Ondo Tropical Rainforest, Nigeria.
Publication Authors:
 Aigbe H. I., Adeyemo T.O., Onyekwelu J.C. And Amadi I.
Year Published:
 2016
Abstract:
In this study, biomass yield residue was quantified and equations developed for Triplochiton scleroxylon, in secondary forests, Ondo State, Nigeria. Plotless sampling technique was used for the study. A total of 31 Triplochiton scleroxylon were randomly selected. Tree identification and detailed growing stock of outside bark diameters at breast height (dbh), base, middle, top and total height were measured for selected trees. Each tree was felled as close to the ground as possible. The logging residues were categorized into stump, stem, branch and foliage. Fresh weights of representative samples from the various logging residues components were obtained and dry-weights to freshweights ratio of the various biomass components were calculated. The results showed that the mean biomass of the residues for Triplochiton scleroxylon was 66.40 kg, 312.98 kg, and 19.56 kg for stem, branches and foliage respectively which indicated that the branch components generated more logging residue than other components. The proportion of residues generated for Triplochiton scleroxylon ranged from 12.00% to 49.02%. The biomass models for logging residue were fitted using dbh predictor. The model developed indicated that logarithmic functions performed better than other form of equation. The findings of this study revealed that there is significant logging residues left to waste in the forest after timber harvest and quantifying this logging residue in terms of biomass model can serve as management tools in ensuring useful planning for economic utilization of the residues. 
Publisher:
 Ghana Journal Of Forestry, 30 (1): 1 – 15
Publication Type:
 Journal
Publication Title:
 Status Of Soil Under Different Forest Types In South-western Nigeria.
Publication Authors:
 Onyekwelu, J.C., El Kateb, H. And Felbermeier, B.,
Year Published:
 2014
Abstract:
Land-use change could be accompanied by changes in soil physical, chemical and/or biological properties. The conversion of degraded forests to plantations could have no effect, positive or negative on soil quality. This study investigated soil status under primary, degraded and Gmelina arborea plantation forests within Oluwa and Omo forest reserves in a rainforest ecosystem in south-western .igeria. Transects method was used in selecting sample plots (20 m x 20 m) in natural forests (primary and degraded) while in Gmelina plantations, simple random sampling was used to select 20 m x 20 m sample plots. Soil samples were collected at four fixed depths (0–15, 15–30, 30–45, 45–60 cm) within a 6 m x 6 m sub-plot. For the purpose of statistical analyses, soil parameters were grouped into: soil physical properties, soil texture, soil nutrition, mineralisation, acidification, and salinity. Bulk density was not significantly different among all forest sites. Forest type had varying effects on the soil physical properties. The hypotheses associated with the equality of the means of soil depths were rejected for all investigated soil parameter groups, implying that the soil parameter groups are dependent on soil depth. Soil properties varied with soil depth, with the values decreasing with decrease in soil depth, except clay, silt and .a, which increased with increasing soil depth. The degree of changes in pH and almost all chemical properties for the various soil depths were not dependent on forest type. The interaction forest site and soil depth was insignificant, indicating that the degree of change from one soil depth to another did not vary with forest site. However, forest site had significant effect on investigated soil parameter groups. Gmelina plantations had significantly lower sand and higher clay content than degraded and primary forests. There was no statistical evidence that soil texture is dissimilar for degraded and primary forests in Omo. There were significant effects of few soil properties, thus the hypothesis associated with equality of both reserves was rejected for nutrition, mineralisation, acidification and salinity. Also, plantations were significantly different from degraded and primary forests in nutrition, mineralisation, acidification and salinity due to significant effect of some soil properties.