Responses of soil and plants to spatio-temporal changes in landscape under different land use in Imo watershed, southern Nigeria

Soil and plant compositions have been affected by human activities in Imo watershed, southern Nigeria. The study examined the responses of soil and plants to changes in landscape under different land use. It was hypothesized that though forest had higher soil organic carbon (OC) and organic matter (OM), it was the most altered land use with substantial loss of biodiversity. Data were collected covering soil properties and plant compositions. Arable land (AL), forestland (FL), grassland (GL), shrubland hills (SL), urban built-up green (UL), Freshwater swamp-mangrove wetland (WL) and water bodies (WB) were classified as the main land use by using ArcGIS 10.1 and Food and Agricultural Organization (FAO) land-use classification system. One-way analysis of variance followed by post-hoc test was used to determine the mean differences in years and land use for various soil properties and plant parameters. Results revealed that soil nutrient concentrations decreased by at least 50% across land use. Leucaena leucocephala, Vernonia amygdalina, Panicum maximum, Lablab purpreus, Vernonia nigritiana and Elaeis guineensis were dominant with high cover. Species diversity showed significantly negative correlations with species evenness and R-factor (p < 0.05), but positive correlations with total nitrogen and OM and OC (p < 0.001). To restore and increase soil and plant biodiversity, human activities need to be regulated by introducing sustainable agriculture and logging.