Document Type
Article
Publication Date
2017
Keywords
Permafrost soils, Carbon in global vegetation, Larch watershed, Siberian forests
Abstract
Permafrost soils store between 1330 and 1580Pg carbon (C), which is 3 times the amount of C in global vegetation, almost twice the amount of C in the atmosphere, and half of the global soil organic C pool. Despite the massive amount of C in permafrost, estimates of soil C storage in the high-latitude permafrost region are highly uncertain, primarily due to undersampling at all spatial scales; circumpolar soil C estimates lack sufficient continental spatial diversity, regional intensity, and replication at the field-site level. Siberian forests are particularly undersampled, yet the larch forests that dominate this region may store more than twice as much soil C as all other boreal forest types in the continuous permafrost zone combined. Here we present above- and belowground C stocks from 20 sites representing a gradient of stand age and structure in a larch watershed of the Kolyma River, near Chersky, Sakha Republic, Russia. We found that the majority of C stored in the top 1m of the watershed was stored belowground (92%), with 19% in the top 10cm of soil and 40% in the top 30cm. Carbon was more variable in surface soils (10cm; coefficient of variation (CV) = 0.35 between stands) than in the top 30cm (CV = 0.14) or soil profile to 1m (CV = 0.20). Combined active-layer and deep frozen deposits (surface – 15m) contained 205kgCm−2 (yedoma, non-ice wedge) and 331kgCm−2 (alas), which, even when accounting for landscape-level ice content, is an order of magnitude more C than that stored in the top meter of soil and 2 orders of magnitude more C than in aboveground biomass. Aboveground biomass was composed of primarily larch (53%) but also included understory vegetation (30%), woody debris (11%) and snag (6%) biomass. While aboveground biomass contained relatively little (8%) of the C stocks in the watershed, aboveground processes were linked to thaw depth and belowground C storage. Thaw depth was negatively related to stand age, and soil C density (top 10cm) was positively related to soil moisture and negatively related to moss and lichen cover. These results suggest that, as the climate warms, changes in stand age and structure may be as important as direct climate effects on belowground environmental conditions and permafrost C vulnerability.
Publication Title
biogeosciences
Volume
14
Issue
18
First Page
4279
Last Page
4294
DOI
https://doi.org/10.5194/bg-14-4279-2017
Required Publisher's Statement
An interactive open-access journal of the European Geosciences Union
Recommended Citation
Webb, E. E., Heard, K., Natali, S. M., Bunn, A. G., Alexander, H. D., Berner, L. T., Kholodov, A., Loranty, M. M., Schade, J. D., Spektor, V., and Zimov, N.: Variability in above- and belowground carbon stocks in a Siberian larch watershed, Biogeosciences, 14, 4279-4294, https://doi.org/10.5194/bg-14-4279-2017, 2017.
Subjects - Topical (LCSH)
Permafrost--Carbon content--Russia; Soils--Carbon content--Russia; Plants--Effects of carbon on; Larches--Carbon content--Russia
Geographic Coverage
Russia
Supplement
Genre/Form
articles
Type
Text
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.
Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.
Language
English
Format
application/pdf
