Edge effects on decomposition in Sphagnum bogs: Implications for carbon storage

Abstract

Peatlands provide multiple ecosystem services, including extensive carbon sequestration and storage, yet many peatlands have been degraded or destroyed. Peatlands' carbon storage capacity is connected to inherently low decomposition rates, causing the buildup of organic matter. This pattern could be explained by waterlogged conditions that reduce the amount of available oxygen for the decomposer community, a low pH that inhibits bacterial decomposition, or colder temperatures lowering metabolic rates. This study focused on edge effects on decomposition in the transition zone (lagg) between Sphagnum bogs and the surrounding forest, with the expectation that decomposition is lowest in the bog and highest in the forest but with a mix of factors causing intermediate decomposition rates near the bog edge. Transitional decomposition rates were measured across six bogs in central Sweden during the summer of 2021, following the Tea Bag Index. Three 20-m transects, each containing seven pairs of tea bags, were buried across the margins of each bog, centered at the edge of the Sphagnum moss. Soil moisture content, pH, and plant composition were also recorded at each burial site, and temperature loggers placed evenly among four of the bogs. Our results

Topography and Time Shape Mire Morphometry and Large‐Scale Mire Distribution Patterns in the Northern Boreal Landscape

“…For example, while small mire patches or laterally merged mires with more complex shapes might favor plant species richness through stronger edge effects (Howie & Meerveld, 2011), birds might be favored by open areas and low tree height, often associated with larger mires (Fraixedas et al., 2017). Furthermore, increased representation of edges in mires with more complex shapes might result in lower carbon accumulation due to better aeration and, hence, decomposition at the edges (Nordström et al., 2022). Even though it is well established that topography and landscape position regulates the water balance and flowpaths, the links between site‐specific mire area and shape distributions and the surrounding catchment areas have rarely been addressed at larger spatial scales and for different land surface ages.…”

Sphagnum mosses, the impact of disturbances and anthropogenic management actions on their ecological role in CO2 fluxes generated in peatland ecosystems

“…In addition, they exhibit a high cation exchange capacity and a proven efficiency in water retention, generating an acidic, humid, and anaerobic environment (Clymo, 1963; Clymo & Hayward, 1982; Kotska et al., 2016; Leroy et al., 2019; Li et al., 2021). These conditions inhibit the action of decomposer extracellular enzymes (Hájek et al., 2011; Kim et al., 2021; Li et al., 2021; Nordström et al., 2022), slowing the degradation of OM and favoring C sequestration in the long term, estimated to be responsible for ca. 50% of C accumulation in peatlands (Piatkowski et al., 2021; Rydin & Jeglum, 2006).…”