Abbey Leigh Marcotte

Wageningen University

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Publication date: 26 mei 2025

University: Wageningen University

From the ashes: Hydrological and biogeochemical responses to wildfire in temperate peatlands

Summary

This thesis investigates the hydrological and biogeochemical responses to wildfire in temperate peatlands, ecosystems historically less prone to fire but increasingly vulnerable due to climate change. Through field observations and laboratory experiments in the Netherlands and the UK, the research examines the impact of smoldering fires and drought on peat chemistry and water quality. Key findings include that ash produced during smoldering generally causes only transient increases in soil pH because alkaline components are quickly leached or neutralized by the acidic peat. However, the combined effects of wildfire and drought significantly alter solute dynamics; while nutrients and base cations are flushed rapidly following initial post-fire storms, the mobilization of legacy pollutants—specifically heavy metals like lead, copper, and zinc—is often delayed, peaking with seasonal re-wetting and increased hydrological connectivity. The study also highlights the role of erosion in transporting metal-rich ash and peat into receiving reservoirs, posing potential chronic risks to potable water sources. These findings underscore the need for long-term monitoring and adaptive management to protect the ecosystem services provided by contaminated temperate peatlands.