Ecosystems have been affected by series of activities that occurred on lands. The effects of land use change on the physical and chemical properties of the soil in Oba Hill Forest Reserve have been studied using standard instrumentation techniques. Results obtained showed that the texture of the soils ranged from loam to sandy loam while the pH of the soils from the four land use types ranged from 4.92 (acidic) to 7.80 (alkaline).The bulk densities in soils from the four land use types are natural forest (1.01 g/m3), teak plantation (1.21 g/m3), farmland (1.55 g/cm3) and residential (1.66 g/m3). Concentration of Mn in soils are higher than Zn, Cu and Fe from the all the studied land use types. Higher mean concentration values of Mn is recorded in soils from natural land (98.12±0.99 mg/kg) followed by plantation land with mean value of 74.32±0.52 while soils from residential land had lowest mean value of 19.59±0.13mg/kg. Soils from the natural land also have the highest mean concentrations value of Fe (69.04±0.26 mg/kg), Zn (21.48±0.11mg/kg) and Cu (15.43±0.04 mg/kg) while least mean concentration values of Fe (25.46±0.03 mg/kg), Zn (8.59±0.01mg/kg) and Cu (3.55±0.01mg/kg) are recorded in residential land. The results revealed that changing in land use types from natural forest to residential land decrease the organic matter, available nitrogen, soil moisture, porosity exchangeable cations, micronutrients and increased the bulk density in the soils. This study has shown that land use types can affect soil properties and existence of essential nutrients in the soils.

ABSTRACT:This study demonstrates the potentials of Geographic Information System (GIS) as a management tool for avenue trees (Street trees) populations in small communities (using Idi-Ishin community, Ibadan, Nigeria as a case study). GIS is a decision support system which integrate data or set of data from different sources, bringing them under the same referencing system in a computer system. An Ikonos Imagery (1m Spatial Resolution) of the study area was digitized to produce a digital map using ArcGIS 10.1 version. The avenue trees species ≥ 5cm diameter at breast height (DBH) was selected for enumeration. These trees were then measured and tagged. The Height, Girth and Geographic location (X &Y coordinate) of the trees were measured with Haga altimeter, Girthing tape and Hand held Global Positioning System (GPS) respectively. The species and families of the trees enumerated were also identified. Data were analysed for basal area (BA) and volume (V). A total number of 43 avenue trees were assessed in Idi-Ishin Community. Roystonea regia accounted for the majority of the avenue trees (25.58%), followed by Polyanthia longiflora (23.26%), Gliricida seprium (20.93%), Eucalyptus toreliana (13.95%), Delunix regea (6.98%). However Terminalia catapa, Terminalia radii, Azadrachita indica and Newbodia levis had the same abundance of 2.33%. It was also observed that the benefits derived from these avenue trees includes; Carbon sequestration, Beautification, Wind break and shade. A spatial relational database was created for the assessed avenue trees using ArcCatalog of ArcGIS 10.1 version. Based on the findings from the study (which serves as baseline information for the management of the avenue trees in the study area), it was therefore recommended that subsequent assessment should be carried out at 3-5 year interval in other to ensure proper and continuous monitoring and updating of the data.