Key plant species and detritivores drive diversity effects on instream leaf litter decomposition more than functional diversity: A microcosm study

Anthropogenic impacts on freshwater ecosystems cause critical losses of biodiversity that can in turn impair key processes such as decomposition and nutrient cycling. Forest streams are mainly subsidized by terrestrial organic detritus, so their functioning conservation status be altered changes forest composition, particularly if these involve the replacement functional groups or loss species. We examined this issue using a microcosm experiment where we manipulated plant diversity (FD) (monocultures low-FD high-FD mixtures, resulting from different combinations deciduous evergreen Quercus species) presence species (Alnus glutinosa), all absence detritivores, assessed effects litter decomposition, cycling, fungal detritivore biomass. found (i) positive detritivore-mediated biomass exclusively when A. glutinosa was present; (ii) negative same microbially mediated Most trends could explained higher palatability trait variability obtained with inclusion alder leaves mixture. Our results support hypothesis consistent slowing down process result loss, hence stream ecosystem functioning, especially (N-fixing) is lost; underscore importance detritivores drivers studied processes.