Potential for large losses of carbon from non-native conifer plantations on deep peat over decadal timescales

TY - JOUR

T1 - Potential for large losses of carbon from non-native conifer plantations on deep peat over decadal timescales

AU - Sloan, Thomas J.

AU - Ratcliffe, Joshua

AU - Anderson, Russell

AU - Gehrels, W. Roland

AU - Gilbert, Peter

AU - Mauquoy, Dmitri

AU - Newton, Anthony J.

AU - Payne, Richard J.

AU - Serafin, Justyna

AU - Andersen, Roxane

N1 - Publisher Copyright: © 2024 The Authors

PY - 2024/11/25

Y1 - 2024/11/25

N2 - Peatland drainage is a large source of anthropogenic CO2 emissions. While conversion to agriculture is widely acknowledged to lead to “irrecoverable” carbon (C) losses, in contrast the C impacts of peatland forestry are poorly understood, especially in intensively managed plantations. Losses of C from peat oxidation are highly variable and can be compensated for by gains of C in trees, depending on the lifecycle of the timber and timescale considered. Here, we used ITRAX scanning to enable rapid detection of the Hekla 4 cryptotephra layer as a reliable chronological marker above which peat properties and C stocks could be compared between open and afforested blanket bog cores in the Flow Country of Northern Scotland. At one site, Bad a’ Cheò, we combine replicated core pair comparisons (n = 19) with timber extraction data to derive net ecosystem C balance over the lifetime of the plantation. Here the reduction in peat C carbon storage above Hekla 4 in afforested samples (67 t C ha−1) is only partially compensated by tree C sequestration (47 t C ha−1), leading to a net ecosystem C balance indicating a loss of 20 t C ha−1 over the 50 years since the plantation was established. At that site, ∼65 % of tree C rapidly returned to the atmosphere, as it was primarily used for heat and power generation. Across the wider Flow country region, a simplified paired sampling method was adopted at eight further sites, finding a either a loss or negligible change in peat C storage above Hekla 4 in afforested samples with a mean loss of 86 t C ha−1 and median loss of 50 t C ha−1. This study suggests that potentially substantial C losses have been an unintended consequence of non-native conifer afforestation over deep blanket bogs.

AB - Peatland drainage is a large source of anthropogenic CO2 emissions. While conversion to agriculture is widely acknowledged to lead to “irrecoverable” carbon (C) losses, in contrast the C impacts of peatland forestry are poorly understood, especially in intensively managed plantations. Losses of C from peat oxidation are highly variable and can be compensated for by gains of C in trees, depending on the lifecycle of the timber and timescale considered. Here, we used ITRAX scanning to enable rapid detection of the Hekla 4 cryptotephra layer as a reliable chronological marker above which peat properties and C stocks could be compared between open and afforested blanket bog cores in the Flow Country of Northern Scotland. At one site, Bad a’ Cheò, we combine replicated core pair comparisons (n = 19) with timber extraction data to derive net ecosystem C balance over the lifetime of the plantation. Here the reduction in peat C carbon storage above Hekla 4 in afforested samples (67 t C ha−1) is only partially compensated by tree C sequestration (47 t C ha−1), leading to a net ecosystem C balance indicating a loss of 20 t C ha−1 over the 50 years since the plantation was established. At that site, ∼65 % of tree C rapidly returned to the atmosphere, as it was primarily used for heat and power generation. Across the wider Flow country region, a simplified paired sampling method was adopted at eight further sites, finding a either a loss or negligible change in peat C storage above Hekla 4 in afforested samples with a mean loss of 86 t C ha−1 and median loss of 50 t C ha−1. This study suggests that potentially substantial C losses have been an unintended consequence of non-native conifer afforestation over deep blanket bogs.

KW - Blanket bog

KW - Bulk density

KW - C stocks

KW - Drainage

KW - Forestry

KW - Tephrochronology

UR - http://www.scopus.com/inward/record.url?scp=85203850175&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2024.175964

DO - 10.1016/j.scitotenv.2024.175964

M3 - Article

C2 - 39222806

AN - SCOPUS:85203850175

SN - 0048-9697

VL - 953

JO - Science of the Total Environment

JF - Science of the Total Environment

M1 - 175964

ER -