The Role of Millipedes in Tropical Ecosystems
Millipedes, which look like centipedes with an extra pair of legs on most of their body segments, are an essential part of tropical ecosystems for their role in decomposing vegetation and cycling nutrients back into the soil. Diplopods can influence decomposition directly by fragmenting leaf litter and indirectly by affecting microbial biomass. Forest Service scientists investigated the direct and indirect effects of millipedes on decomposition in a subtropical wet forest in Puerto Rico.
They studied the influence of the substrate by using three leaf species with varying leaf mass and leaf area ratios and the effect millipede density has on the previously mentioned direct and indirect effects. The scientists found that the remaining leaf mass and leaf area were lowest in the species (Dacryodes excelsa) with the lowest leaf mass-to-leaf area ratio. Significantly less leaf mass was remaining from microcosms with the highest density of millipedes.
Soil microbial biomass was significantly higher under D. excelsa leaves than for the other litter species, but microbial biomass did not significantly differ among the different millipede densities. They found that the effect of millipedes differed, depending on the lignin content of the litter species when the litter species were looked at separately, with the highest lignin-content leaf species (Rourea surinamensis) having significantly less leaf mass remaining with millipedes than without at the last collection.
Litter species and the density of millipedes significantly affected soil pH. The research results show that millipedes have a direct effect on decomposition by fragmenting litter, and this effect depends on litter quality. The results also suggest that millipedes have little or no indirect effect in terms of influencing microbial biomass.
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