Litter chemistry prevails over litter consumers in mediating effects of past steel industry activities on leaf litter decomposition

• Published in: The Science of the total environment 2015-12, Vol.537, p.213-224
• Main Authors: Lucisine, Pierre, Lecerf, Antoine, Danger, Michaël, Felten, Vincent, Aran, Delphine, Auclerc, Apolline, Gross, Elisabeth M., Huot, Hermine, Morel, Jean-Louis, Muller, Serge, Nahmani, Johanne, Maunoury-Danger, Florence
• Format: Article
• Language: English
• Subjects: Abundance; Animals; Biodiversity and Ecology; Consumers; Decomposition; Environmental Monitoring; Environmental Sciences; Exposure; Invertebrates; Leaf characteristics; Leaf litter decomposition; Litter; Litter bags; Plant Leaves - chemistry; Populus tremula; Soil (material); Soil - chemistry; Soil biota communities; Soil functioning; Soil Microbiology; Soil Pollutants - analysis; Soil pollution; Toxic; Trace metals
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.07.112

Soil pollution has adverse effects on the performance and life history traits of microorganisms, plants, and animals, yet evidence indicates that even the most polluted sites can support structurally-complex and dynamic ecosystems. The present study aims at determining whether and how litter decomposition, one of the most important soil ecological processes leaf, is affected in a highly trace-metal polluted site. We postulated that past steel mill activities resulting in soil pollution and associated changes in soil characteristics would influence the rate of litter decomposition through two non-exclusive pathways: altered litter chemistry and responses of decomposers to lethal and sub-lethal toxic stress. We carried out a litter-bag experiment using Populus tremula L. leaf litter collected at, and allowed to decompose in, a trace metal polluted site and in three unpolluted sites used as controls. We designed a fully-factorial transplant experimental design to assess effects of litter origin and exposure site on the rate of litter decomposition. We further determined initial litter chemistry, fungal biomass, mesofauna abundance in litter bags, and the soil macrofauna community. Irrespective of the site of litter exposure, litter originating from the polluted site had a two-fold faster decomposition than litter from the unpolluted sites. Litter chemistry, notably the lignin content, seemed most important in explaining the degradation rate of the leaf litter. Abundance of meso and macro-detritivores was higher at the polluted site than at the unpolluted sites. However, litter decomposition proceeded at similar rates in polluted and unpolluted sites. Our results show that trace metal pollution and associated soil and litter changes do not necessarily weaken consumer control on litter decomposition through lethal and sub-lethal toxic stress. [Display omitted] •We evaluated leaf litter decomposition on a Technosol polluted by trace metals.•Litter produced at the polluted site decomposed faster than unpolluted litter.•Detritivores were found in higher abundances in the polluted site.•Litter decomposition rate was similar in the polluted and unpolluted sites.•Contrary to expectations metal stress does not systematically impact soil functioning.