Interactions of soil properties and dominant tree canopy species with vegetation recruitment within a mine wasteland of the Zambian Copperbelt

Abstract

Mine wastelands can affect soil’s properties, leading to stunted plant growth. However, little is known about the effect of different categories of soil parameters on plant recruitment under harsh conditions such as mine wastelands. The study aimed to determine how various soil properties contribute to vegetation recruitment around dominant tree canopy species within a Cu mine wasteland of the Zambian Copperbelt province. Soil and understory tree vegetation were sampled from 8 m radius circular plots beneath the canopies of dominant tree species. Grass and herb samples were collected from smaller, nested plots with a 1 m radius. Soil properties were analysed and biodiversity metrics (i.e. species richness, abundance, Shannon-Wiener and Simpson indices) were calculated. Data analysis included Kruskal-Wallis tests to assess soil properties variations among canopy species, a Weighted Linear Mixed Model (W-LMM) to evaluate the fixed effects of dominant tree canopy species on the biodiversity metrics and Random Forest models to identify key soil variables influencing biodiversity metrics. Results showed minimal variation in soil properties among canopy species. Dominant tree canopy species significantly influenced biodiversity, with Ficus capensis and Ficus craterostoma enhancing richness and diversity in tree and herb layers, while grass layers showed minimal responses. Heavy metals (e.g. Zr, Sn, Pb) reduced diversity, whereas nutrients like Fe, Ca, and Mg positively affected recruitment, explaining up to 40.5 % of variance in tree richness. These results emphasize the importance of soil nutrient management and species selection in improving plant recruitment, offering key considerations for enhancing ecological restoration efforts in mine tailings dams.