Tree Density and Leaf Litter as Drivers of Ground-Active Arthropod Diversity in Zoological Garden, Southeastern Nigeria

Abstract

Ground-active arthropods are vital contributors to ecosystem functioning and serve as sensitive indicators of habitat quality. However, their diversity within managed wildlife environments such as zoological gardens remains poorly studied, particularly in tropical Africa. This study assessed the diversity and habitat drivers of ground-active arthropods in the Zoological Garden of the University of Nigeria, Nsukka. Arthropods were sampled using pitfall traps across four plots differing in vegetation structure, tree density, and leaf litter depth between June and September 2024. Specimens were identified to the lowest possible taxonomic level, and diversity indices including Menhinick’s Richness index (Dmg), Shannon–Wiener diversity (H′), and Pielou’s evenness (J′) were calculated. A total of 1,140 individuals representing nine arthropod orders, 16 families, and 21 species were recorded. Plots characterised by higher tree density and deeper leaf litter supported greater arthropod abundance. Exploratory regression analyses indicated positive relationships of arthropod abundance with tree density (R² = 0.90, p = 0.03) and leaf litter depth (R² = 0.96, p = 0.01). These findings highlight the importance of vegetation complexity and litter accumulation in sustaining arthropod biodiversity within zoological gardens.