Biodiversity at the plant–soil interface: microbial abundance and community structure respond to litter mixing

Abstract

The interactive eVects of diversity in plants and microbial communities at the litter interface are not well understood. Mixtures of plant litter from diVerent species often decompose diVerently than when individual species decompose alone. Previously, we found that litter mixtures of multiple conifers decomposed more rapidly than expected, but litter mixtures that included conifer and aspen litter did not. Understanding the mechanisms underlying these diversity eVects may help explain existing anomalous decay dynamics and provide a glimpse into the elusive linkage between plant diversity and the fungi and bacteria that carry out decomposition. We examined the microbial communities on litter from individual plant species decomposing both in mixture and alone. We assessed two main hypotheses to explain how the decomposer community could stimulate mixed-litter decomposition above predicted rates: either by being more abundant, or having a diVerent or more diverse community structure than when microbes decompose a single species of litter. Fungal, bacterial and total phospholipid fatty acid microbial biomass increased by over 40% on both conifer and aspen litter types in mixture, and microbial community composition changed signiWcantly when plant litter types were mixed. Microbial diversity also increased with increasing plant litter diversity. While our data provide support for both the increased abundance hypothesis and the altered microbial community hypothesis, microbial changes do not translate to predictably altered litter decomposition and may only produce synergisms when mixed litters are functionally similar.

Changes in soil microbial substrate utilization in response to altered litter diversity and precipitation in a Mediterranean shrubland

“…However, the understanding of how these two drivers of global change interact and affect ecosystem functioning is limited. In particular, the consequences for the functioning of the soil microbial communities, known to exhibit a strong control over the carbon (C) and nutrient cycles, have been little explored (Rodríguez-Loinaz et al 2008;Chapman and Newman 2009). …”

Positive effects of plant diversity on soil microbial biomass and activity are associated with more root biomass production

“…The PLFAs identified in samples of the study were as follows: 12:1 3OH, 13:0 2OH, 14:0, 14:0a, 15:0 iso, 15:0a, 15:0i, 16:0, 16:0a, 16:0 N alcohol, 16:1w7c, 17:0, 17:0a, 17:1 iso, 18:0, 18:1w7c, 18:1w9c, 18:2w6, 9c, 18:3w6, 9, 12c, 19:1 iso and 19:0 10-methyl. Total PLFAs were used as an index of total living microbial biomass (Chapman and Newman 2010).…”

Litter Supply as a Driver of Microbial Activity and Community Structure on Decomposing Leaves: a Test in Experimental Streams

“…Much less is known about effects of litter mixing on microbial diversity and activity. Greater diversity of microbes was found in a forest in mixed-species litter compared to singlespecies litter (22), whereas fungal diversity in streams was unaffected by litter mixing (23).…”