Quantifying soil carbon accumulation in Alaskan terrestrial ecosystems during the last 15 000 years
Northern high latitudes contain large amounts of soil organic carbon (SOC), of which Alaskan terrestrial ecosystems account for a substantial proportion. In this study, the SOC accumulation in Alaskan terrestrial ecosystems over the last 15 000 years was simulated using a process-based biogeochem...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/13/6305/2016/bg-13-6305-2016.pdf |
| Summary: | Northern high latitudes contain large amounts of soil organic carbon (SOC),
of which Alaskan terrestrial ecosystems account for a substantial proportion.
In this study, the SOC accumulation in Alaskan terrestrial ecosystems over
the last 15 000 years was simulated using a process-based biogeochemistry
model for both peatland and non-peatland ecosystems. Comparable with the
previous estimates of 25–70 Pg C in peatland and 13–22 Pg C in
non-peatland soils within 1 m depth in Alaska using peat-core data, our
model estimated a total SOC of 36–63 Pg C at present, including
27–48 Pg C in peatland soils and 9–15 Pg C in non-peatland soils.
Current vegetation stored 2.5–3.7 Pg C in Alaska, with 0.3–0.6 Pg C in
peatlands and 2.2–3.1 Pg C in non-peatlands. The simulated average rate of
peat C accumulation was 2.3 Tg C yr<sup>−1</sup>, with a peak value of
5.1 Tg C yr<sup>−1</sup> during the Holocene Thermal Maximum (HTM) in the early
Holocene, 4-fold higher than the average rate of 1.4 Tg C yr<sup>−1</sup> over
the rest of the Holocene. The SOC accumulation slowed down, or even ceased,
during the neoglacial climate cooling after the mid-Holocene, but increased
again in the 20th century. The model-estimated peat depths ranged from 1.1 to
2.7 m, similar to the field-based estimate of 2.29 m for the region. We
found that the changes in vegetation and their distributions were the main
factors in determining the spatial variations of SOC accumulation during
different time periods. Warmer summer temperature and stronger radiation
seasonality, along with higher precipitation in the HTM and the 20th century,
might have resulted in the extensive peatland expansion and carbon
accumulation. |
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| ISSN: | 1726-4170 1726-4189 |