Plant functional type indirectly affects peatland carbon fluxes and their sensitivity to environmental change. (2nd October 2020)

• Record Type: Journal Article
• Authors: Whitaker, Jeanette; Richardson, Harriett R.; Ostle, Nicholas J.; Armstrong, Alona; Waldron, Susan
• Is Part Of: European journal of soil science. Volume 72:Number 2(2021)
• Page Start: 1042
• Page End: 1053
• Publication Date: 2020-10-02
• Subjects: carbon cycling -- climate change -- greenhouse gas emissions -- methane -- peat -- plant functional type; Soil science -- Periodicals; 631.4
• DOI: 10.1111/ejss.13048
• Languages: English
• ISSNs: 1351-0754

Abstract

Abstract: The sensitivity of peatland carbon (C) fluxes to changes in climate and hydrology are uncertain due to the complex interactions between plants and peat properties. In this study we examine how peat cores taken from under three plant functional types (PFT) (bryophyte, graminoid and ericoid) differ in their biotic and abiotic properties and how this indirectly modulates the response of C fluxes to environmental change. Peat cores taken from under three PFTs had their aboveground vegetation removed to exclude direct plant‐mediated effects, and were incubated in a temperature × water table factorial experiment at 12, 14 and 16°C (air temperature) with the water table level −25, −15 or −5 cm below the peat surface. Carbon dioxide (CO2 ) and methane (CH4 ) fluxes were measured over 11 months. Emissions of CO2 and CH4 increased with temperature, with strong positive (CH4 ) and negative (CO2 ) interactions with increasing water table level. There were significant effects of removed PFT on the environmental sensitivity of CH4, but not CO2 fluxes. CH4 emissions were greatest in peat with graminoid PFT removed at the warmest temperature but these indirect effects were not explained by peat abiotic or biotic properties, which did not differ between PFTs. These results show that climate change‐induced expansion of graminoids in northern peatlands will have direct and indirect effects on C fluxes and the stability of peatland C stores. These responses will be determined by the interactive effects of vegetation composition, hydrology and warming on methane‐cycling microbial communities. Highlights: Peatland carbon flux strength under a changing climate is influenced by PFT. Peat from under graminoid PFT emits more methane than peat from under bryophyte or ericoid PFT. Prior PFT cover influenced methane emissions, but did not affect peat abiotic or biotic properties. Increases in graminoid cover with climate change could indirectly increase peatland methane fluxes.