Post-mine succession and short term effects of coal mining in a Guinea savanna ecosystem

Abstract

This research aimed to determine the impact of coal mining on the variety of plants and their successional dynamism in the Guinea savanna. Five sites in Nasarawa State, Nigeria, were sampled: abandoned sites (36 years post-mining), actively mined sites C and D (for two years), and one control site, E. To evaluate its diversity and species composition, alpha diversity (species richness, Shannon and Simpson diversity indices), beta diversity, and indicator species studies were employed. There were 74 plant species observed throughout the study, but 55 showed a significant connection with the locations. Control site E contained the most significant proportion of native, perennial, and nitrogen-fixing plants, indicating a high level of alpha diversity. Due to the high OC and accessible N at abandoned site A, it possesses the most significant number of tree species (75%) in the Fabaceae family, indicating ongoing natural succession. Thus, succession in abandoned site A was created based on the microhabitat's interaction with the plant species' eco-functionality. Although extrinsic factors such as grazing and farming delayed successional processes in abandoned site B, the greatest observed beta diversity was linked with the eco-morphological characteristics of rare plant species Boerhavia erecta and Kallstroemia pubescens. Active mining sites C and D had reduced soil nutrients and a greater abundance of invasive annual forb species such as Ageratum conyzoides, Asystasia gangetica, Urena lobata, Sida linifolia, and Mimosa pudica. Therefore, artificial restoration of abandoned coal site B is recommended to expedite the reclamation process.