Extent of forest depletion from 1986-2015 as a consequence of land use in Andoni Local Government Areas of Rivers State, Nigeria

Abstract

The study investigated the extent of forest depletion between 1986 and 2015 in Andoni LGA, Rivers State, Nigeria. Landsat images of 1986, 2000 and 2015 were employed for the study. Image classifications were done in Erdas Imagine using supervised classification with maximum likelihood module whereby six major classes of landuse were identified namely forest, built up area, waterbodies, mangrove, cultivated land, and bareground/sand. The area in square kilometers of each land use type in each year was computed in ArcGIS 10.0 and simple calculations were used to compute the change and percentage change of each landuse from one period to the other. Landuse probability of change to other landuse in 2025, 2035 and 2045 were done Idrisi Selva 17.0. Findings showed that forest coverage was 125.95 km² (39.56%) in 1986 and 74.14 km² (23.29%) in 2015. Forest, cultivated land, and waterbodies decreased by 41.14%, 80.8% and 76.52% while built up area, mangrove and bareground/sand increased by 303.64%, 18.67% and 3.64% from 1986 to 2015. Bareground/sand and built-up areas replaced forest with 21.23 km² (38.40%) and 20.26km² (3.64%) respectively. The study predicted that 3.68% of bareground/sand, 0.47% of mangrove and 3.51% of built up area had probability of replacing forest by 2025 while 5.09%, 2.1% and 7.32% of bareground/sand, mangrove and built up area had the probability of changing to forest by 2045. The study recommended that strict legislation, policies and strategies should be put in place to protect the forests from undue exploitation.

Keywords: Forest depletion; geo-information; supervised classification; Andoni LGA