Compositional stability of peat in ecosystem-scale warming mesocosms.

Area of Science:

• Environmental Science
• Soil Science
• Climate Change Research

Background:

• Peatlands act as significant carbon sinks due to high carbon fixation exceeding decomposition.
• Projected climate warming may increase heterotrophic respiration, potentially turning peatlands into carbon sources.
• The Spruce and Peatlands Response Under Changing Environments (SPRUCE) experiment investigates peatland responses to climate forcing.

Purpose of the Study:

• To assess the chemical changes in peatland soils after five years of experimental warming.
• To quantify the relative abundance of carbohydrate and aromatic compounds using Fourier Transform Infrared Spectroscopy (FT--IR).

Main Methods:

• Experimental warming using enclosures and deep peat heating (0–+9°C above ambient).
• Analysis of peat samples from the uppermost 2 meters.
• Fourier Transform Infrared Spectroscopy (FT-IR) for chemical compound analysis.

Main Results:

• No significant changes were observed in the relative amounts of labile and recalcitrant chemical compounds after five years of warming.
• Peat chemistry remained compositionally stable despite observed net carbon losses and peat mass reduction.
• The ratio of chemical moieties in peat showed no significant alteration over the four-year experimental period.

Conclusions:

• Peatland carbon stores appear compositionally stable in the short term (four years) under experimental warming.
• Despite potential mass loss, the chemical structure of peat resists significant change from warming.
• Further research is needed to understand long-term carbon stability and release mechanisms.