Leaf-litter decomposition of pioneer plants and detritivore macrofaunal assemblages on coal ash disposals in southern Brazil

We studied the leaf-litter decomposition of three pioneer plants (Cynodon dactylon – grass; Ricinus communis – shrub and Schinus terebinthifolius – tree), and the diversity of the associated detritivore macrofaunal assemblages in a system affected by two coal ash disposals (fly ash and boiler slag) in southern Brazil. We conducted a litter bag experiment in the area during a period of 140 days. We found that the decomposition rate of R. communis was more than 80% faster (k-value 20.7) than the other species. This result agrees with its low C:N ratio, high N (%), and increased abundance of detritivores in the first days of its decomposition. On the other hand, this leaf-litter supported the lowest invertebrate species richness. C. dactylon and S. terebinthifolius leaf-litters were similar in decomposition rates and macrofauna diversity. The type of ash disposal system did not affect leaf-litter decomposition and detritivore densities; on the other hand, the morphospecies composition was distinct in the different sites.

Research highlights
► In coal ash disposals at southern Brazil, the decomposition of Ricinus communis was 80% faster than Cynodon dactylon and Schinus terebinthifolius leaf-litter.
► R. communis leaf-litter supported increased abundance but decreased species richness of detritivores.
► C. dactylon and S. terebinthifolius leaf-litters were similar in decomposition rates and colonizing macrofauna diversity.
► Detritivore morphospecies composition was distinct in the fly ash and boiler slag disposal sites.