A Preliminary Study on the Relationship between Arthropod Diversity and Vegetation Diversity in Four Contrasting Ecosystems in Hanthana Mountain Range of Sri Lanka, during the Post-Monsoon Dry Season

Abstract

This study assesses the relationship between arthropod and vegetation diversity in four ecosystems with different types of vegetation, during a post-monsoonal season. We determined the arthropod diversity in vegetation surrounding an aquatic environment (AQ), a broad-leaved wet, evergreen forest ecosystem (BL), a Pinus caribaea monoculture plantation (PN), and a Pinus plantation artificially enriched with indigenous broad-leaved tree species (PNEN) located in the Hanthana mountain range, Sri Lanka. Arthropods randomly sampled from three randomly selected sites (5 m × 5 m) of each ecosystem were identified up to the highest possible taxa using standard identification keys. Woody and herbal vegetation was identified via a plant census. Arthropod and vegetation diversities were computed separately for each site using the Shannon–Wiener Index (H). Arthropods of 68 species and 43 families were found. AQ had the greatest arthropod diversity (H 2.642), dominated by Olios spp., followed by BL (H 2.444), dominated by a tettigonid species, Oxytate spp. and Psechrus spp. PN was third (H 1.411), dominated by Dicaldispa spp. PNEN had the lowest (H 1.3500), dominated by an ant species. Contrastingly, PNEN had the highest plant diversity (H 2.614) and PN, the lowest (H 0.879). In AQ, BL, and PN, the arthropod diversity was linearly dependent on plant diversity (R2 0.423, p≤ 0.001), whereas it was not so when PNEN was also included (R2 0.008, p≤ 0.001). This shows that higher plant diversity contributes to greater arthropod diversity in ecosystems where human intervention is minimal. But this pattern was not visible in PNEN, which is an artificially created ecosystem.