Research Review: Rewiring Peatland Plant–Microbe Networks

The Question

How do peatland ecosystems—specifically the plants and microbes—respond to environmental changes?

Peatlands occupy roughly 3% of the global land area and are rich in stored carbon—containing roughly 25% of the world’s soil carbon^2-3, double the amount contained by the world’s forests!

Maintaining a positive carbon balance, where carbon uptake exceeds carbon release, in peatlands helps mitigate carbon–climate feedback. This balance largely depends on the rate of primary production and decomposition^4-5. In undisturbed peatlands, the rate of decomposition is low, however when peatlands get disturbed by environmental changes or human activity, the microbes within the ecosystem have an opportunity to process the organic matter, spiking the rate of decomposition and carbon release^6-7.

The Idea

Robroek et al. postulate that enviro–climatic changes will trigger both plant and microbial communities to turnover, leading to changes in ecosystem interactions.

The researchers explored this idea by sampling plant and microbial communities from three geographically distinct European peatlands and collecting climate and environmental data for the most important drivers for the turnover in peatland plant community composition from various databases, such as WorldClim.

After collecting the samples and environmental data, Robroek et al.

• Characterized plant and microbial communities;
• Assessed how enviro–climatic conditions relate to compositional differences in plant and 16S rRNA‐derived microbial communities; and 
• Assessed how changes in composition affects plant–microbial networks: the interactions between plants and microbial communities.

The Findings

Plant and Microbial Composition

• Plant andarchael community composition were highly distinctive between sites, whereas bacterial community composition was strikingly similar between sites
• Sulphur deposition and temperature seasonality are largely driving the differences in community structure and network for all three communities.

Plant-Microbial Networks

• The network size and complexity differed between the three sites, with > 70% fewer interactions in Cena Mire and Dosenmoor compared with Degerö Stormyr. In the vascular plant community, Rhynchospora alba played a major role in nearly all plant-prokaryote networks
• Prokaryote associations with plant species tend to be specific—attributed to the fact that species richness in the prokaryotic community massively exceeds plant species richness

Network Rewiring

• Network turnover is higher than species turnover and network compositions between sites were more dissimilar than species compositions between sites
• Network diversity was mostly driven by turnover in interactions between species that are common in the three sites, rather than by novel interactions driven by changes in the community composition

The Future

Previously, Morriën et al. showed that increased network complexity can enhance soil carbon uptake efficiency, without substantial changes in microbial biomass and without major changes in the composition of plant communities. This indicates that interaction turnover can have major implications on ecosystem processes.

The next step is to link changes in plant–microbe interactions to peatland carbon cycling and to identify specific plant and microbial organisms that drive the carbon uptake function.

Fully characterizing the key drivers and organisms in peatland carbon cycling will help build better ecosystem models, facilitating carbon release forecasting, and potentially regulation and peatland restoration.

Technical Highlight

The researchers used the FastRNA Pro Soil‐Direct Kit and FastPrep Instrument to extract Total RNA from 0.75 g of wet peat (7.8% ± 2.5 dry peat). The extracted RNA was reverse transcribed to complementary DNA (cDNA) and further processed for amplicon-based sequencing.

Researchers investigating complex microbial ecosystems or a variety of sample types—from tough plants to soil and sludge to bacteria—can utilize MP Bio’s wide range of sample preparation tools. Use our RNA extraction kits and FastPrep Instruments to homogenize samples and obtain high quality nucleic acids for downstream cell biology and molecular applications, such as metagenomic sequencing.

References

1. Robroek, Bjorn JM, et al. "Rewiring of peatland plant–microbe networks outpaces species turnover." Oikos 130.3 (2021): 339-353.
2. Nichols, Jonathan E., and Dorothy M. Peteet. "Rapid expansion of northern peatlands and doubled estimate of carbon storage." Nature Geoscience 12.11 (2019): 917-921.
3. Xu, Jiren, et al. "PEATMAP: Refining estimates of global peatland distribution based on a meta-analysis." Catena 160 (2018): 134-140.
4. Clymo, R. S. "Experiments on breakdown of Sphagnum in two bogs." The Journal of Ecology (1965): 747-758.
5. Dorrepaal, Ellen, et al. "Are growth forms consistent predictors of leaf litter quality and decomposability across peatlands along a latitudinal gradient?." Journal of Ecology 93.4 (2005): 817-828.
6. Jassey, Vincent EJ, et al. "Tipping point in plant–fungal interactions under severe drought causes abrupt rise in peatland ecosystem respiration." Global Change Biology 24.3 (2018): 972-986.
7. Lamentowicz, Mariusz, et al. "Unveiling tipping points in long-term ecological records from Sphagnum-dominated peatlands." Biology letters 15.4 (2019): 20190043.
8. Morriën, Elly, et al. "Soil networks become more connected and take up more carbon as nature restoration progresses." Nature communications 8.1 (2017): 1-10.