Earthworms and soil properties in Tabasco, Mexico

Tabasco, in southeastern Mexico, is one of the states where deforestation has occurred as a result of the implementation of agricultural systems. Only 4% of its territory is tropical rainforest and areas used for forestry. For this reason, it is important to study the soil fauna in these natural relicts. Sixteen sites (4 natural and 12 managed systems) were studied in order to identify earthworm species communities, using the TSBF method. Nineteen species were found, 14 native and 5 exotic, belonging to the families Megascolecidae, Glossoscolecidae and Ocnerodrilidae. Sites that presented the highest species diversity were Tropical rain forest (9), which also contained high organic matter content (11.9 ± 5.7%), total nitrogen (0.66 ± 0.2%), and available phosphorus (18 ± 7.56 mg kg−1), and Traditional cacao cultures (13). The highest earthworm biomass was found in a tree plantation of Mangifera indica, and the highest density was observed in riparian vegetation. A significant relationship was observed between earthworm density and clay content (Spearman's rho 0.3, P = 0.01).