Soil Macrofauna Diversity as Indicators of Land Use Intensity Across a Gradient in Ondo State, South West Nigeria

Soil macrofauna, including earthworms, termites, beetles, and myriapods, perform essential ecosystem engineering functions and respond sensitively to land use intensification. This study assessed soil macrofauna diversity and abundance as indicators of land use intensity across a gradient from intact forest to intensively cultivated farmland in Ondo State. Six land use categories were selected: intact rainforest, secondary forest, cocoa agroforest, mixed food crop farm, cassava monoculture, and oil palm plantation. Five replicate sites per land use type were surveyed using monolith extraction methods at two depth intervals. Soil macrofauna were identified and counted, and functional group assignment was made based on feeding and burrowing ecology. Soil physicochemical properties including organic matter, moisture, pH, and bulk density were measured to characterise the macrofaunal habitat. Results showed a clear negative gradient in macrofaunal abundance and diversity from intact forest to intensive monoculture, with earthworm and termite abundance declining by 74 and 62 percent respectively between forest and cassava monoculture. Cocoa agroforest supported intermediate macrofaunal diversity, significantly higher than annual crop systems. Structural equation modelling showed soil organic matter and moisture as primary mediators of land use effects on macrofaunal communities. The study provides empirical benchmarks for macrofauna-based soil quality assessment in Ondo State and recommends adoption of macrofaunal monitoring in agricultural environmental impact assessments. Keywords: soil macrofauna, land use intensity, earthworms, Ondo State, soil ecology.