Role of plant-microbe interaction for C dynamics in northern peat bogs

Abstract

Peatlands in the Northern Hemisphere serve as critical carbon sinks, having sequestered substantial amounts of carbon over millennia. Their long-term carbon storage capacity positions them as key contributors to nature-based solutions for climate change mitigation. Northern peatlands are thus of utmost importance from a global climate system perspective. However, these important C stores are at risk and are susceptible to the impact of enviro-climatic change, with cascading effects on ecosystem processes and functions. C sequestration in peatlands hinges on the delicate imbalance between primary production and decomposition. Microbial communities and associated metabolic processes are possibly fundamental in driving feedback between enviro-climatic change and the peatland C cycle. Microbial communities are important regulators of belowground nutrient cycling processes including C dynamics.

Peatlands are experiencing climate warming and drainage which leads to shifts in vegetation cover and alterations in water table depth, that may drastically effects decomposition rates through change in microbial community composition and metabolic activity. Moreover, other consequences of climate change – e.g. dramatic wildfire – directly affect peatland microbial communities, including the alteration in community composition and diversity, and consequently comprise their C sink function.

In this thesis, I investigated the effects of long-term plant functional type (PFT) removal, specifically ericoids and graminoids, on microbial communities across two microhabitats-lawns and hummocks, characterized by differing water table levels. I show that the fluctuation in water table level across contrasting microbiota modulate the taxonomic composition of prokaryotic communities, while distinct PFTs varying in litter inputs and rhizodeposits significantly influence the abundance of prokaryotes and were microhabitat dependent. I further highlight the potential of plant microbe interaction to examine the relative and interactive impact of plant functional types and microhabitats on peatland decomposition dynamics. The result implies an important role of distinct PFTs, through their impact on microbial mediated metabolic activity, along the lawn-hummock gradient in deriving the process of decomposition. Finally, I demonstrate the abrupt effect of wildfire and post-fire recovery of prokaryotic communities in northern peat bog at soil different depths, that can help us to reveal that how microbial dynamics contribute to resilience and recovery of these C rich peatland ecosystem following fire disturbance.

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Identifiers

ORCID for Marc Dumont: orcid.org/0000-0002-7347-8668

ORCID for Bjorn JM Robroek: orcid.org/0000-0002-6714-0652

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