This study was carried out to examine the efficacy of Strict Nature Reserves (SNR) as a means of biodiversity conservation. This was achieved by assessing the status of the forest in terms of tree species diversity, abundance and growth yield. Data were collected from four plots of one hectare size each, randomly located in the forest. In each plot, all tree species (dbh ≥ 10 cm) were identified and their height, diameter at breast height (dbh) and diameters at the top, middle and base were measured. There were 387 stems ha-1, belonging to 94 tropical hardwood species, 80 genera and 30 families in the SNR. The most abundant species and family were Celtis zenkeri of Ulmaceae family (41 stems ha-1) and Sterculiaceae (10 species), respectively. The Shannon-Wiener index (3.75) and evenness (0.82) and other diversity indices were very high, indicating that the forest is a potential biodiversity hotspot. The indices compared favourably with several protected areas that are biodiversity hotspots. In addition, the total basal area and volume of 674.33 m2 and 4,646.93 m3 and the vertical and horizontal structure confirm that the SNR is a mature natural forest. This study provides a baseline for the management of protected areas in developing countries and it shows the potential of in situ method in nature conservation.
Wood anatomy of five Cola species was investigated to identify and describe anatomical features in search of distinctive characters that could possibly be used in the resolution of their taxonomy. Transverse, tangential and radial longitudinal sections and macerated samples were prepared into microscopic slides. Characteristic similarity and disparity in the tissues arrangement as well as cell inclusions were noted for description and delimitation. All the five Cola species studied had essentially the same anatomical features, but the difficulty posed by the identification of Cola acuminata and Cola nitida when not in fruit could be resolved using anatomical features. Cola acuminata have extensive fibre and numerous crystals relative to Cola nitida, while Cola hispida and Cola millenii are the only species having monohydric crystals. Cola gigantea is the only species that have few xylem fibres while other species have extensive xylem fibre. These features have proved very functional and strongly of diagnostic value in the classification and delimitation of the studied Cola species.
This study examined logging damage to non-targeted neighbouring plant species and the forest ecosystem in a tropical forest in Ondo State, southwest Nigeria. Tree growth variables were recorded before and after felling, as was the number of crosscut logs. All plant species damaged during harvesting were enumerated and identified and the nature and level of the damage was also determined. Data providing demographic information, causes of damage to residual plants and measures to reduce the damage were obtained from the loggers using questionnaires. Data were collected on selective logging of 41 tree species. Despite selective logging practices, during felling, plants were damaged, soil compacted and the ecosystem disturbed. The observed damage to residual trees and seedlings ranged from 5% to 70% and it is therefore concluded that reduced impact logging and training of loggers is necessary to minimise the impacts.
Understorey (plant, insect and mesofauna) and bird biodiversity conservation was assessed for three forest plantation types in rainforest ecological zone of Nigeria. Young and old stands of the exotic, indigenous and mixed tree species were selected from each two plantation sites. Eight sample plots of 20m x 20m (with 2m x 2m quadrant at the centre) were randomly laid within each plantation. All understorey plants within the quadrants were identified and recorded. For insect species, four pitfall traps (8cm x 10cm) were placed at least 5 m apart within each plot. Insects that fell into the trap were captured and preserved with 1.5L of 0.2% formalin. Flying insects were captured with sweep net and light net. Bird count was conducted using line transect and indirect methods. Understorey plant richness varied across the plantations. Species richness did not follow any clear trend with plantation age for exotic species but old indigenous species plantations had more species richness than young ones while the reverse was the case in mixed stands. Insect species richness followed the order: exotic species > indigenous species > mixed species plantations. There were significant differences in all the biodiversity indices of the various plantations. Identified bird species totalled 38. Bird species richness followed the order: old G. arborea > old growth N. diderrichii > young G. arborea plantations. The biodiversity indices of the plantations compared favourably with that of natural forests, thus indicating that forest plantations establishment has not led to understorey biodiversity loss but rather to their conservation.
This study assessed the effects of exploitations in natural forest ecosystems on tree species diversity and environmental conservation. This was achieved by comparing tree species diversity and yield in an unlogged forest (Strict Nature Reserve) and a forest reserve where active logging is in progress in Ondo State, Nigeria. Eight plots (20 m x 20 m) were assessed in each site using systematic sampling techniques. All living trees with dbh >10 cm were identified, categorized into families with their diameter at breast height (dbh) measured in each plot. Shannon-Weiner and species evenness indices were used to assess and compare tree species diversity and abundance. The results show that the tropical humid forest is very rich in tree species, as a total of 54 different tropical hardwood species from 23 families were encountered in both forest types. There were 46 species distributed among 21 families in the unlogged forest and 24 species in 14 families in the logged forest. Shannon-Weiner diversity index of 3.16 and 3.03 and evenness index of 0.83 and 0.81 were also obtained for the unlogged and logged forest, respectively. Every variable computed had a higher value in the unlogged forest relative to the logged forest. In the unlogged forest, the species with the highest number of occurrence was Mansonia altissima A. Chev. (80 stems/ha). Caesalpinoidae and Sterculiaceae families had the highest number of species (6).
Timber harvesting data are very essential for sustainable management of forest resources. These data are very scarce in developing countries. Therefore, we collected and analyzed data on the rate of timber production of the free areas and the forest reserves in Ondo State, Nigeria. The data collected from the State Department of Forestry’s official records, annual reports and files were on the species, volume and number of different economic timbers exploited on monthly basis between 2003 and 2005. Analyses were done with the student t-test and one-way analysis of variance. Results reveal that the highest numbers of species, families and stems were exploited in the free areas when compared with what was exploited from the reserves for the three-year period. However, the total volume of trees removed from the reserves was significantly higher (p<0.05) than what was removed from the free areas. A total 60 different indigenous hardwood species in 25 families were exploited from the free areas, and 57 in 23 families from the reserves. The total number of stems exploited from the forest ecosystem of Ondo state during the three-year period stood at 111,377 with an estimated volume of 295,089.67 m3. While the mean number of stems and volume exploited per annum is 37,125 and 98,363.22 m3, respectively. The monthly average number of stems and volume is 3 094 and 8 196 m3, respectively. The t-test results show that there were significant differences (p<0.05) in number of stems and volume removed from the free areas and the reserves. The ANOVA results reveal a significant increase (p<0.05) in logging activities between the years of 2003 and 2004 but there was a decline in year 2005. This trend reveals that economic timber species were disappearing from the forests and the ecosystem was seriously disturbed during logging activities. Principles for achieving the goals of sustainable forest management (SFM) and urgent conservation measures to mitigate the consequences of forest degradation were suggested.
The efficacies of some indigenous herbal dyes for use in staining plant materials were examined to obtain non-toxic, eco-friendly and cheap stains for use in plant histology. Dye extracts from Bixa orellana, Curcuma domestica, Lonchocarpus cyanescens and Pterocarpus osun were used to stain wood sections using the existing standard staining procedures with little modification. All the extracts had affinity for the fibre and vessel elements except the extract from L. cyanescens. The extracts from C. domestica and B. orellana had higher selectivity than those of P. osun for fibre. From the results of the absorbance curves, each of the dye extracts from all speciese had minimum of two peaks, indicating that they had two or more colour imparting chromophores except dye extract from C. domestica. All the dye extracts were acidic with pH range of 3.77 to 6.77. Therefore, this study shows that dye extracts from B. orellana, C. domestica and P. osun could be solitarily or in combination with artificial dyes for plant histological staining.
Tree adaptation to climatic change and carbon stocks dynamics were investigated in the Permanent Sample Plot (PSP 29) in Akure Forest Reserve, Ondo State Nigeria. 6 sample plots of 50 x 50 m in size were systematically laid in cluster to collect data on tree species in the sample plots. All tree species with dbh ≥ 10cm encountered on each plot were identified and the dbh were measured. The dbh of all tagged tree species, whose measurement has been repeatedly measured from the period of 1934 to 2001, were recorded. Data on Climatic Variables were obtained from the Nigeria Metrological Agency. Tree biomass and carbon stocks were calculated using equations. Correlation analysis was done to determine relationship between the forest data and climatic variables. The results showed a change in climatic conditions across the study period. 61 tree species in 24 families were encountered. The dbh increment and general increase in mean biomass and carbon stocks were noticeable in the period of observation. Apart from rainfall, the impact of other variables is not significant. Temperature had a weak negative but not significant correlation with tree variables. A better understanding of our forests adaptive capacity to climate change is highly imperative.
A detailed morphological study of the leaf epidermis of the tropical genera of some species of some species Acalypha, Bridelia, Euphorbia, Hura, Jatropha, Manihot and Ricinus in Nigeria is presented. the study revealed several interesting epidermal features some of which have not been previously reported in the genera. Leaf epidermal characters such as pattern of epidermal cells, types of stomata and presence of trichomes are constant in some species and variable in others and thus of great significance in understanding the relationships between and within species. Leaves are amphistomatic in all species except in Bridelia ferruginea, Euphorbia heterophylla, Euphorbia pulcherrima and Jatropha gossypifolia which are hypostomatic. the syomata lenght, width, density and index also vary in different species.
Tree species diversity, biovolume and forest stand structure were investigated in natural forest ecosystem located around some selected communities in the bitumen producing area of Ondo state, Nigeria. Two forest reserves and four free areas distributed in 4 Local Government Areas (LGA) of the state were selected for data collection, out of the total 6 LGAs in the bitumen belt of the state. The two forest reserves are Oluwa FR at Legge in Odigbo LGA and Eba Island FR in Ese-Odo LGA while the four free areas are located close to each of Omotoso community (Odigbo LGA), Ode-Aye community (Okitipupa), Igbo-Egunrin community (Ilaje) and Igbotako community (Okitipupa). Eight plots of equal size (20 x 20 m) were located in each of the selected location, using systematic line transect sampling design. In each plot, all living trees with dbh ≥10 cm were identified with their botanical names and their dbhs were also measured. The results of the study reveal that there were ninety nine (99) tropical hardwood timber species (range: 21 to 48 species per selected forest). These species were distributed among twenty nine (29) families. While Funtumia elastica has the highest population distribution across the selected communities’ forest, Euphorbiaceae was the dominant family in the entire area. Although there was a moderate variation in the biodiversity indices among the selected communities’ forest, the Shannon-Weiner diversity index of H1 = 4.02 and species evenness of E = 0.88 were obtained for the entire study area. Tree density summing up to 2,740 trees/6 ha varied moderately, with a range of 361–609 tree/ha, among the communities. Though most of the trees encountered belonged to the lowest diameter size class, the mean basal area and biovolume were 26.69 m2/ha and 262.36 m3/ha respectively. Recommendations guiding the decision on the allocation of the communities’ forest to the bitumen exploratory industries are made and the need for good forest management of the prospective area of bitumen exploration of Ondo state is emphasized. This is to prevent the imminent loss of biological diversity that would eventually accompany the exploration.