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

Abstract

To date the field of ecological stoichiometry has focused mainly on aquatic systems concentrating on macro-elements. We investigated terrestrial systems and included microelements to study the elemental transfer in the detritivorous food web. We compared 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 litter, herbivores, detritivores, predators and omnivores. Based on elemental concentrations of elements differences between trophic groups were visualized using PCA. At all sites litter C:N, C:P, C:K and C:Na ratios were higher than in animals. Invertebrate trophic groups were significantly different from each other in C:Cu, C:Zn and C:Ca ratios. The calculated resource:consumer N:P ratio suggests that invertebrates in studied forests are N limited and not P limited. Similar patterns at all sites suggests that metal pollution at the studied intensity slightly affects the transfer of elements in the terrestrial macro-invertebrate food web.