Peat deposits store more carbon than trees in forested peatlands of the boreal biome

Abstract

Peatlands are significant carbon (C) stores, playing a key role in nature-based climate change mitigation. While the effectiveness of non-forested peatlands as C reservoirs is increasingly recognized, the C sequestration function of forested peatlands remains poorly documented, despite their widespread distribution. Here, we evaluate the C sequestration potential of pristine boreal forested peatlands over both recent and millennial timescales. C stock estimates reveal that most of the carbon stored in these ecosystems is found in organic horizons (22.6–66.0 kg m−2), whereas tree C mass (2.8–5.7 kg m−2) decreases with thickening peat. For the first time, we compare the boreal C storage capacities of peat layers and tree biomass on the same timescale, showing that organic horizons (11.0–12.6 kg m−2) can store more carbon than tree aboveground and belowground biomass (2.8–5.7 kg m−2) even over a short time period (last 200 years). We also show that forested peatlands have similar recent rates of C accumulation to boreal non-forested peatlands but lower long-term rates, suggesting higher decay and more important peat layer combustion during fire events. Our findings highlight the significance of forested peatlands for C sequestration and suggest that greater consideration should be given to peat C stores in national greenhouse gas inventories and conservation policies.

BAWLD-CH<sub>4</sub>: a comprehensive dataset of methane fluxes from boreal and arctic ecosystems

“…Bogs have low pH (< 5), low concentrations of dissolved ions, and low nutrient availability, resulting from a lack of hydrological connectivity to surrounding mineral soils. Vegetation is commonly dominated by Sphagnum mosses, lichens, and woody shrubs and can be either treed or treeless (Beaulne et al, 2021). Our description of Bogs also includes what is commonly classified as treed swamps, which generally represent ecotonal transitions between peatlands and upland forests (Canada Committee on Ecological (Biophysical) Land Classification et al, 1997).…”

Maximizing the effectiveness of national commitments to protected area expansion for conserving biodiversity and ecosystem carbon under climate change

“…Proactive protection of above‐ and below‐ground carbon within intact ecosystems provides an important mitigation pathway distinct from that offered by improved intensive management or restoration of agricultural, grassland, and forested landscapes, such as widely publicized tree planting initiatives (Fargione et al, 2018; Griscom et al, 2017; Law et al, 2018; Seddon et al, 2021). An approach that focuses on avoided conversion of natural areas at meaningful scales is especially important in landscapes such as peatlands and old forests that hold large quantities of ecosystem carbon that, if lost due to disturbance, would be irrecoverable within a timescale meaningful to addressing climate change (Beaulne et al, 2021; Goldstein et al, 2020; Law et al, 2018). The large amount of land required, the convergence of biodiversity and climate change agendas (Roberts et al, 2020), and feedbacks between biodiversity loss and climate change (Arneth et al, 2020) should compel planners to seek to holistically align objectives for new protected areas that maximize co‐benefits (Díaz et al, 2020).…”

Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands

“…A total of 11 samples were submitted to A. E. Lalonde AMS Laboratory (University of Ottawa, Canada) for accelerator mass spectrometry radiocarbon dating ( 14 C). Plant macrofossil remains were carefully selected to date peat initiation, the last fire event, and main transitions in vegetation composition at each sampling site (Beaulne et al 2021). The 14 C dates were calibrated using the IntCal13 calibration curve (Reimer et al 2013).…”