Microbial diversity-ecosystem function relationships across environmental gradients
Microbial Ecology and Applied Microbiology
Final Report Abstract
Soils are central for terrestrial ecosystem functions including nutrient cycling, sustaining plant growth, water purification, litter decomposition, and carbon storage and these functions are carried by microbial communities, which are among the most diverse in the world. Research into spatial variability in the distribution of bacteria, archaea, fungi and protists has revealed major drivers of soil biodiversity across biomes, but this limited data has rarely been linked to ecosystem functions. This project aimed to explore the relationship between microbial diversity and decomposition, as a major ecosystem function carried out by soil microbes, in variable environmental contexts. It builds on the engagement of iDiv with the TeaComposition network (teacomposition.org) who performs measurements of decomposition and organic matter turnover. Data on physicochemical parameters, climate, and decomposition rates from 319 sites in 34 countries in six continents were combined with NGS-based microbial diversity data (bacteria, archaea, eukaryotes, and specifically fungi, arbuscular mycorrhizal fungi, and nematodes). Such integrative and comprehensive information is critical to better understand the drivers of soil microbial communities, risks to their biodiversity and potential functional consequences, for parametrizing global to local models of biodiversity and function distribution and to predict potential future changes. The project was strongly delayed by the COVID-19 pandemic, which occurred at the start of the project. However, interaction with the NCCT overall went smoothly and the NCCT offered very professional service, also in times when their processes were disrupted by COVID-19. 3,003 sets of amplicon sequencing data for metabarcoding by six different targets (2,843 unique sample x target combinations) and 344 sets of shotgun metagenome data were analysed, yielding information on more than 100,000 amplicon sequence variants and 400 million genes. Our data reflect that most taxa are observed in only a few of the samples. α-diversity of bacteria, most fungi and nematodes decreased with increasing latitude in temperate and boreal/arctic biomes, while archaea, other small eukaryotes and arbuscular mycorrhizal fungi showed less latitudinal structure. Further, significant correlations with observed α-diversity diversity could be identified for the elevation of the sampling location, soil texture, and pH, as well as climatic variables such as mean annual temperature and precipitation, with different directions and extents in the different soil organisms. These results underline the range of responses of the different parts of soil biodiversity to factors that are well known to influence the diversity of commonly studied groups such as bacteria and fungi. We found an overall positive relationship between the teabag index (k; a measure of degradation function) and observed α-diversity, in particular for fungi and generally eukaryotes and, to a lesser extent, bacteria. Nematodes, arbuscular mycorrhizal fungi and archaea did not show the same trends. Interestingly, the relationship of remaining green tea was positive for nematodes and arbuscular mycorrhizal fungi, while there was a negative relationship between the diversity of other fungi and general eukaryotes and the amount of roiboos left after a given time. No relationship between bacterial diversity and the amount of left-over rooibos was observed. We can speculate that the greater diversity in the mostly saprotrophic fungi and some eukaryotic taxa actually contributes to the degradation potential of the soils. Due to the delays, the analysis of the soil biodiversity and functional data is still on-going. Integration of the different metabarcoding datasets is another direction that we are working on. With the shotgun metagenomics, our focus lies on the more detailed analysis of the genes which may play a role in the soil functions of interest, but also on the description of genomes that are not yet well represented by metagenomics sequencing projects. While new research on soil microbial biodiversity and function has been published in the recent years, we still consider this dataset as a valuable resource which can be published with a large impact because of the number of target taxa, collected functional data and global scope. It is also an important data source for on-going follow-up research.
Publications
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Microbial diversity-ecosystem function relationships across environmental gradients. Research Ideas and Outcomes, 6.
Heintz-Buschart, Anna; Guerra, Carlos; Djukic, Ika; Cesarz, Simone; Chatzinotas, Antonis; Patoine, Guillaume; Sikorski, Johannes; Buscot, Francois; Küsel, Kirsten; Wegner, Carl-Eric & Eisenhauer, Nico
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Large‐scale drivers of relationships between soil microbial properties and organic carbon across Europe. Global Ecology and Biogeography, 30(10), 2070-2083.
Smith, Linnea C.; Orgiazzi, Alberto; Eisenhauer, Nico; Cesarz, Simone; Lochner, Alfred; Jones, Arwyn; Bastida, Felipe; Patoine, Guillaume; Reitz, Thomas; Buscot, François; Rillig, Matthias C.; Heintz‐Buschart, Anna; Lehmann, Anika & Guerra, Carlos A.
