Does metal pollution affect the stoichiometry of soil-litter food webs?

Abstract

To date, the field of ecological stoichiometry has focused mainly on macro-elements in aquatic systems. We investigated terrestrial systems and included micro-elements in the study to assess the elemental transfer in a detritivorous food web. We compared the food webs of six sites differing in the type and degree of metal pollution along two forest transects contaminated with copper or zinc. We measured 11 elements in the litter, herbivores, detritivores, predators and omnivores. Based on the concentrations of the elements, the differences between the trophic groups were visualized using PCA. At all the sites, the litter C:N, C:P, C:K and C:Na ratios were higher than those in the animals. The C:Cu, C:Zn and C:Ca ratios of the invertebrate trophic groups were significantly different from each other. The calculated resource:consumer N:P ratio suggests that invertebrates in the studied forests are N limited but not P limited. The presence of similar patterns at all the sites suggests that metal pollution at the studied intensity somewhat affects the transfer of elements in terrestrial macro-invertebrate food webs.