Root litter decomposition is suppressed in species mixtures and in the presence of living roots

Abstract

Plant species diversity and identity can significantly modify litter decomposition, but the underlying mechanisms remain elusive, particularly for root litter. Here, we aimed to disentangle the mechanisms by which plant species diversity alters root litter decomposition. We hypothesised that (1) interactions between species in mixed communities result in litter that decomposes faster than litter produced in monocultures; (2) litter decomposition is accelerated in the presence of living plants, especially when the litter and living plant identities are matched (known as home‐field advantage). Monocultures and a mixture of four common grassland species were established to obtain individual litter and a ‘natural’ root litter mixture. An ‘artificial’ mixed litter was created using litter from monocultures, mixed in the same proportions as the species composition in the natural litter mixtures based on qPCR measurements. These six root litter types were incubated in four monocultures, a four‐species mixture and an unplanted soil. Root decomposition was strongly affected by root litter identity and the presence, but not diversity, of living roots. Mixed‐species litter decomposed slower than expected based on the decomposition of single‐species litters. In addition, the presence of living roots suppressed decomposition independent of the match between litter and living plant identities. Decomposition was not significantly different between the ‘natural’ and ‘artificial’ root litter mixtures, indicating that root‐root interactions in species mixtures did not affect root chemical quality. Synthesis. Suppressed decomposition in the presence of living roots indicates that interactions between microbial communities associated with living roots and root litter control root litter decomposition. As we found no support for the importance of home‐field advantage or interspecific root interactions in modifying decomposition, suppressed decomposition of mixed‐species litter seems to be primarily driven by chemical rather than biotic interactions.

Nitrogen Application and Rhizosphere Effect Exert Opposite Effects on Key Straw-Decomposing Microorganisms in Straw-Amended Soil

“…In addition, the rhizosphere effect led to an enrichment of the Fusarium genus, which is a primary pathogen responsible for causing root rot in wheat [ 63 ]. The above root-indued changes in KSDMs indicate that the presence of plant roots has a negative effect on straw decomposition [ 19 , 64 , 65 ] and that straw return may also cause some plant root diseases [ 66 ].…”

“…Therefore, biogeochemical cycling mediated by microbes within this interface is distinctive [ 18 ]. Heredia-Acuña et al [ 19 ] found that the presence of living roots decreased the cumulative decomposition rate of root litter in a greenhouse simulation experiment. However, previous studies of straw decomposition in agricultural ecosystems have paid little attention to this interface.…”

Plant Diversity Response to Environmental Factors in Yellow River Delta, China

“…Through correlation analysis, a noteworthy negative correlation between soil organic carbon and vegetation biomass carbon was identified in the Yellow River Delta. This observation could be attributed to a complex interplay of factors in the Yellow River Delta [66], including poor soil retention, prolonged exposure to flowing water, and human disturbance [20,31]. These factors collectively influence soil organism activity and the decomposition rate of litter, resulting in decreased stability and accumulation of litter carbon in the soil [67].…”