Associations between soil macroinvertebrate assemblages and physicochemical properties of tropical pasture soils in coastal Ecuador

Abstract

Soil macroinvertebrates mediate key soil processes, but field evidence is scarce in coastal Neotropical pastures. This study evaluated how soil physicochemical properties covary with macroinvertebrate abundance and diversity in tropical pastures of Manabí, Ecuador. Thirty-five cattle farms, seven per locality, were sampled by convenience between April and July 2022. Eleven physicochemical variables (0–20 cm) and macroinvertebrates from four 50×50 cm monoliths per farm (30 cm depth) were analyzed at taxonomic group level. Diversity indices and principal component analysis were applied. Of 19,358 individuals in seven groups, Oligochaeta reached 64.20% of abundance, with a mean density of 553 individuals m-2. Cation exchange capacity and clay content contributed most to physicochemical variation; diversity was lowest where physical conditions were most restrictive. Although the measured properties were adequate for pasture production, macroinvertebrate density was less than half the worldwide reference, indicating that physicochemical characterization alone did not capture soil biological condition.