Abstract
Abstract. Climate change can strongly alter soil microbial functioning via plant–microbe interactions, often with important consequences for ecosystem carbon and nutrient cycling. Given the high degree of intraspecific trait variability in plants, it has been hypothesized that genetic shifts within plant species yield a large potential to control the response of plant–microbe interactions to climate change. Here we examined if sea-level rise and plant genotype interact to affect soil microbial communities in an experimental coastal wetland system, using two known genotypes of the dominant salt-marsh grass Elymus athericus characterized by differences in their sensitivity to flooding stress – i.e., a tolerant genotype from low-marsh environments and an intolerant genotype from high-marsh environments. Plants were exposed to a large range of flooding frequencies in a factorial mesocosm experiment, and soil microbial activity parameters (exo-enzyme activity and litter breakdown) and microbial community structure were assessed. Plant genotype mediated the effect of flooding on soil microbial community structure and determined the presence of flooding effects on exo-enzyme activities and belowground litter breakdown. Larger variability in microbial community structure, enzyme activities, and litter breakdown in soils planted with the intolerant plant genotype supported our general hypothesis that effects of climate change on soil microbial activity and community structure can depend on plant intraspecific genetic variation. In conclusion, our data suggest that adaptive genetic variation in plants could suppress or facilitate the effects of sea-level rise on soil microbial communities. If this finding applies more generally to coastal wetlands, it yields important implications for our understanding of ecosystem–climate feedbacks in the coastal zone.
Highlights
Climate change strongly affects soil microbial decomposition, with important consequences for global carbon (C) and nutrient cycles (Davidson and Janssens, 2006; Dijkstra et al, 2010)
Enzyme activities were only affected by flooding frequency in soils planted with the intolerant genotype, whereas none of the four enzyme activity (EEA) were affected in soils planted with the tolerant genotype (Table 1)
Our data suggest genotype–sea-level rise (SLR) interaction effects on the soil microbial community structure (Fig. 5). This finding is in agreement with a recent observational study on genotype– environment interactions in terrestrial ecosystems, suggesting that climate-driven reduction of genetic variation in Populus angustifolia phenology affects soil fungi-to-bacteria ratios (Ware et al, 2019), and a laboratory experiment demonstrating interaction effects of drought and rapid evolution in Brassica rapa on soil microbial community structure
Summary
Climate change strongly affects soil microbial decomposition, with important consequences for global carbon (C) and nutrient cycles (Davidson and Janssens, 2006; Dijkstra et al, 2010). It is not sufficient to only study the direct effects of abiotic climate change drivers on soil microbial communities and resulting changes in ecosystem functioning. Plantmediated indirect effects of climate change on soil microbial communities need to be examined (Bardgett et al, 2008; Van der Putten et al, 2013). Prior work on a wide range of ecosystems indicated that changes in plant productivity and community composition control soil microbial functioning in response to climate change, often with marked effects on ecosystem C as well as greenhouse-gas and nutrient dynam-. Tang et al.: Plant genotype controls blue carbon ics (Fuchslueger et al, 2014; Mueller et al, 2020; Stagg et al, 2018; Ward et al, 2013)
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