The study evaluated the impact of crude oil pollution on natural regeneration of plant species in a major oil-producing community in the Niger Delta region of Nigeria. Three sites-unpolluted site (US), polluted and untreated site (PUS), and polluted and treated site (PTS)-were purposively chosen for the study. The seedling emergence method was used to evaluate soil seed banks in the various sites at two depths, 0 to 10 cm and 10 to 20 cm. Woody-plant species richness, abundance, and diversity were higher in the US seed bank than in the PUS and PTS seed banks. The highest number of non-woody plants was observed in the US, followed by the PTS, and then the PUS. Both species richness and diversity of non-woody plants were highest at the US, followed by the PUS, and lowest in the PTS. Woody species in the US seed bank were 87.5% and 80% dissimilar with those of the PUS and PTS at 0-10 cm and 10-20 cm respectively. No variation was observed between woody species in the PUS and PTS seed banks. Non-woody species at 0−10 cm US seed bank were 73.08% dissimilar with those of PUS at the two soil depths and 81.48/88.46% dissimilar with those of the 0-10/10-20 cm of the PTS respectively. At 10-20 cm, non-woody species of the US were 69.66% dissimilar with those from each of the two soil depths in PUS; and 73.91/81.82% dissimilar with those of 0-10/10-20 cm of the PTS respectively. Non-woody species variation between the PUS and PTS was higher at 10-20 cm than 0-10 cm. The poor seed bank attributes at the polluted sites demonstrates that crude oil pollution negatively affected the natural regeneration potential of the native flora because soil seed banks serve as the building blocks for plant succession. Thorough remediation and enrichment planting are recommended to support the recovery process of vegetation in the polluted areas.

A survey of the avifaunal resources was conducted in the three campuses (Choba, Abuja, and Delta) of the University of Port Harcourt, Nigeria to ascertain their bird species composition, abundance, diversity, and affinity for different tree species. Bird census was carried out on twelve focal trees in each of the three campuses for a period of six months. Shannon-Wiener (H) and Simpson (1-D) diversity indices were used to measure the diversity of bird species in each of the campuses, while similarity in bird species between campuses was ascertained using Sorensen's similarity index (SI).

The charcoal business is rapidly spreading in Nigeria without adequate knowledge of the soil impact. This study examined the impact of charcoal production on selected soil physico-chemical properties and the spatial extent of such impacts. Soil samples were collected at the core of charcoal production sites and at 5m and 10m intervals from the core in North, South, East and West directions, before and after charcoal production. Soil samples were analyzed for particle size distribution, pH, Ca, K, Na, Mg, total N, available P, organic C, Mn, Fe, Cu, Zn, and Bo, using standard analytical laboratory procedures. Student t-test was used to test for significant differences in soil properties before and after charcoal production at different locations. Change index (%) was computed for different locations to ascertain the extent of change in soil properties following charcoal production. There were no significant differences (p > 0.5) in percentage sand, silt and clay before and after charcoal production at the core and both 5m and 10m distances in the four directions. Mn, Fe, Cu, Zn, B, pH, exchangeable cations and percentage base saturation increased after charcoal production and varied significantly (p < 0.5) before and after production especially at the core. Organic C, total N and available P increased by 0.82%, 0.15% and 13.10mg/kg respectively at the core after charcoal production. Indices of change for soil properties were highest at the core and decreased with increasing distance from the core. The study showed that charcoal production increases the level of most soil chemical properties and that such increase diminish with an increasing distance from the centre of the production site. However, longer period of sampling at specific time intervals is recommended to ascertain the longevity or otherwise of such impacts.

This study was conducted to investigate the value perceptions of native tree species in urban landscape by three groups of environmental stakeholders -residents, estate developers and construction companies that reside in Abuja, the Nigeria's Federal Capital Territory. A Multi-Criteria Analysis (MCA) of landscape scale ecosystem functions and services valuation scenarios were used. A total of one hundred and eighty (180) sets of questionnaire were distributed equally among the three stakeholders (60 each) to ascertain their perceptions on the need to protect native tree species by asking them to rank eight reasons why the protection of native tree species is important in urban/city landscape. The reasons ranked were (i) Aesthetics and beautification of environment, (ii) Microclimatic and cooling effect, (iii) Windbreak, (iv) Erosion control, (v) Conservation of native Ihuma et al.; AJEE, 11(2): 1-10, 2019; Article no.AJEE.52829 2 tree species, (vi) Obstruction of view to enhance privacy (vii) Economic value of the species and, (viii) Any other reason. Results showed that Aesthetics and beautification of environment ranked first by a combination of all stakeholders, and also by Estate Developers alone, while Erosion control and Economic value of the species were ranked first by the Residents and the Construction Companies, respectively. Stakeholders' mean scores for Aesthetics & beautification of environment, Microclimatic & cooling effect, Conservation of native tree species, and Obstruction of view to enhance privacy, varied significantly (p < 0.05) while there was no significant differences in their mean scores for Windbreak, Erosion control, and Economic value of the species. The differences in the stakeholders' perception of the value of native trees as revealed by the rankings and significant differences in scores for some of the value criteria to a large extent underscore the values they place on them which in turn will influence their attitude towards the conservation and protection of the species. Therefore, the need for effective environmental education and enlightenment campaigns to sensitise all stakeholders on the overall values and roles of native trees in the city, is emphasized. Original Research Article

Impact of land use changes and varying levels of habitat disturbance on tree populations was evaluated using the spatial analogue technique of studying ecosystem dynamics. Three sites with low, moderate, and high levels of disturbance were purposively chosen from the Biodiversity Conservation Area (BCA), an Unprotected Secondary Regrowth (USR), and an Arable Farmland (AF) respectively, for the study. Tree density and alpha diversity were evaluated in each site. The level of tree species compositional similarity/variation was also ascertained for each pair of the sites, and the extent of change in populations of individual tree species measured for the unprotected sites -USR and AF. Total tree density was highest in BCA (466 trees/hectare) followed by USR (317 trees/hectare) and AF (73 trees/hectare). Tree diversity was highest and lowest in BCA and AF respectively. Tree species compositional variation was higher between BCA and each of USR & AF (66.7%), than between USR and AF (57.1). Harungana madagascariensis, Berlinia grandiflora, and Eleais guineensis were the most abundant tree species in BCA, USR, and AF, respectively. Although, populations of many tree species were found to be drastically reduced or completely lost in the unprotected sites, improvement was observed in populations of few species with Spondias mombin having the highest improvement index (314.29%) in USR while E. guineensis had the highest improvement index (72.7%) in AF. S. mombin is highly valued in the study area because of its edible fruits and diverse medicinal attributes while palm oil and palm kernel oil from E. guineensis contribute immensely to rural livelihoods. Hence, the rural dwellers tend to favour and encourage their growth.