Sensitivity of peatland litter decomposition to changes in temperature and rainfall

Abstract

Changes to climate are projected over the next 50 years for many peatland areas. As decomposition of peat-forming vegetation is likely to be intrinsically linked to these changes in climate, a clear understanding of climate-peat dynamics is required. There is concern that increased temperature and decreased precipitation could increase the rate of decomposition and put the carbon sink status of many peatlands at risk, yet few studies have examined the impact of both climatic factors together. To better understand the sensitivity of peatland decomposition to changes in both temperature and precipitation and their interaction, we conducted a short-term laboratory experiment in which plant litters and peat soil were incubated, in isolation, in a factorial design. Treatments simulated baseline and projected climate averages derived from the latest UK climate change projections (UKCP09) for Exmoor, a climatically marginal peatland in SW England. Regular carbon dioxide flux measurements were made throughout the simulation, as well as total mass loss and total dissolved organic carbon (DOC) leached. The largest effect on carbon loss in this multifactor experiment was from substrate, with Sphagnum/peat releasing significantly less C in total during the experiment than dwarf shrubs/graminoids. Climate effects were substrate specific, with the drier rainfall treatment increasing the DOC leaching from Calluna, but decreasing it from Sphagnum. Partitioning between CO 2 and DOC was also affected by climate, but only for the peat and Sphagnum samples, where the future climate scenarios (warmer and drier) resulted in a greater proportion of C lost in gaseous form. These results suggest that indirect effects of climate through changes in species composition in peatlands could ultimately turn out to be more important for litter decomposition than direct effects of climate change from increased temperatures and decreased rainfall.

Differential responses of litter decomposition to warming, elevated CO2, and changed precipitation regime

“…In this study, the effect size of warming was the most robust in peatland, which was related to the response of peatland to warming. Recent studies have indicated that warming in peatlands could cause changes in the species composition (Bell et al 2018;Ward et al 2015), soil enzymatic activities (Bragazza et al 2013), and microbial functional groups (Jassey et al 2013), thus affecting the litter decomposition rate. Our study also showed that the process of litter decomposition was significantly inhibited when the warming was greater than 5°C (Fig.…”

Prescribed burning impacts on ecosystem services in the British uplands: A methodological critique of the EMBER project

“…Many of these variables are known to affect the ecohydrology of upland river basins (e.g. Simmons, 2003; Durance & Ormerod, 2007; Yallop, Clutterbuck, & Thacker, 2010; Armstrong, Holden, Luxton, & Quinton, 2012; Ritson et al, 2014; Armstrong, Waldron, Ostle, Richardson, & Whitaker, 2015; Parry et al, 2015; Bell et al, 2018). For example, Armstrong et al (2012) found that peatland vegetation type effects dissolved organic carbon (DOC) levels within soil and drain water samples.…”

The Multiscale Monitoring of Peatland Ecosystem Carbon Cycling in the Middle Taiga Zone of Western Siberia: The Mukhrino Bog Case Study

“…The expenditure part of the carbon cycle, due to peat decomposition, is highly dependent on rapid changes in peat surface temperature and on the slower changes in temperature and moisture content of the deeper peat [72]. Mass loss of plant remains through decomposition gives a valuable measurement of net carbon loss, which can be useful for comparing ecosystem or litter substrates.…”