Agroforestry for Reclamation of Imperata Grassland: Earthworm as indicator for soil health

This conference paper assesses agroforestry as a reclamation strategy for Imperata cylindrica grasslands in Solok Regency, West Sumatra (Andisols, ~1200–1500 m a.s.l.), using earthworm density and biomass as a soil health indicator. Thirty-two plots across eight land-use systems — intensive and extensive agriculture, unreclaimed grassland, coffee-based agroforestry aged 1-3, 4-6 and >7 years, old multistrata agroforestry (AFMT) and remnant secondary forest — were sampled in July–August 2024 for microclimate, canopy cover, basal area, standing litter, and earthworms (TSBF monolith method, three depths). Earthworm numbers peaked in AFMT (370 ind./m² at 0-10 cm; 130.52 g/m² biomass) and were near zero under cropped land; conversion of grassland initially depressed populations before partial recovery. Neither basal area nor canopy cover predicted earthworm abundance (R²=0.05–0.09), whereas standing litter explained roughly 28-30% of the variation, identifying organic matter input rather than tree structure as the operative driver. The authors conclude that agroforestry reclamation improves soil health via land cover, litter inputs and earthworm habitat, while noting that short sampling windows may not capture seasonal population dynamics.