Microbial responses to physico-chemical alterations during peatland restoration

Abstract

Peatlands are critical carbon stores, yet many have been degraded by human
activities, turning them into a net source of carbon to the atmosphere and freshwater environments. Efforts to restore the carbon sink capacity of peatlands have been accelerating in recent years. The fate of stored carbon is largely governed by microorganisms, who act as the primary control on carbon and nutrient cycling. Understanding how restoration measures impact microbial communities and their function is therefore central to determining their success. This project examines prokaryote community responses to restoration in severely degraded temperate contexts. It aims to determine key physico-chemical variables which control the composition of microbial communities and shape their function. By coupling detailed characterisation of geochemistry and the microbiome, the consequences of microbial community shifts for the peatland carbon store are considered.
In upland ombrotrophic peat, where recovery has proceeded from eroded
surfaces, organic matter quality is determined as a stronger predictor of community composition than water table position. Distinct microbial communities are identified under degraded and re-vegetated surfaces, and functional profiling reveals contrasting life-strategies reflecting the availability of organic substrates. Revegetated areas support higher microbial biomass, with elevated dissolved organic carbon and CO2 concentrations evidencing altered carbon cycling following recovery.
Rewetting in a lowland context is also considered, given the broadening
emphasis on restoration of agricultural peatlands. Microbial characterisation methods reveal limited recovery in the first year after restoration and highlight the role of deep drainage and nitrogen-enrichment as drivers of community dynamics. Depth trends are clearly linked to oxygen penetration in these peat profiles, and marker taxa for the position of the redox boundary are identified, which can be used as highly relevant proxies in ongoing monitoring.
The findings further our knowledge of microbial responses to restoration and
can inform management decisions and our understanding of restoration outcomes.

Date of Award	4 Feb 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Casey C Bryce (Supervisor), Rich D Pancost (Supervisor), Angela Gallego-Sala (Supervisor), Robert I. Griffiths (Supervisor), Bradley Welch (Supervisor) & Penny J Johnes (Supervisor)