Increased coniferous needle inputs accelerate decomposition of soil carbon in an old-growth forest
Persistent URL
Author(s)
Crow, Susan E.
Lajtha, Kate
Bowden, Richard D.
Yano, Yuriko
Brant, Justin B.
Caldwell, Bruce E.
Sulzman, Elizabeth W.
Date Issued
January 8, 2009
Abstract
Changes in temperature, precipitation, and atmospheric carbon dioxide (CO2) concentration that are expected in the coming decades will have profound impacts on terrestrial ecosystem net primary production (NPP). Nearly all models linking forest NPP with soil carbon (C) predict that increased NPP will result in either unchanged or increased soil C storage, and that decreased NPP will result in decreased soil C storage. However, linkages between forest productivity and soil C storage may not be so simple and direct. In an old-growth coniferous forest located in the H.J. Andrews Experimental Forest, OR, USA, we experimentally doubled needle litter inputs, and found that actual soil respiration rates exceeded those expected due to the C added by the extra needles. Here, we estimated that this ‘priming effect’ accounted for 11.5–21.6% of annual CO2 efflux from litter-amended plots, or an additional 137–256 g C m 2 yr 1 loss of stored C to the atmosphere. Soil priming has seasonal, with greatest amounts occurring in June–August coincident with peaks in temperature and dry summer conditions. As a result of priming,mineral soil was more resistant to further mineralization during laboratory incubations. Soil lignin-derived phenols in the Double Litter plots were more oxidized than in the control, suggesting that the soil residue was more degraded. Our hypothesis that excess dissolved organic C produced from the added litter provided the link between the forest floor and mineral soil and a substrate for soil priming was not supported. Instead, the rhizosphere, and associated mycorrhizal fungi, likely responded directly to the added aboveground litter inputs. Our results revealed that enhanced NPP may lead to accelerated processing of some stored soil C, but that the effects of increased NPP on ecosystem C storage will be based on a net balance among all ecosystem C pools and are likely to be ecosystem-dependant. Forest C models need to include these complex linkages between forest productivity and soil C storage.
Journal
Forest Ecology and Management
Department
Biology
Citation
Crow, S.E., Lajtha K., Bowden, R.D., et al. (2009). Increased coniferous needle inputs accelerate decomposition of soil carbon in an old-growth forest. Forest Ecology and Management, 258: 2224-2232. doi: 10.1016/j.foreco.2009.01.014.
Publisher
Elsevier
Version of Article
Published article
Embargo
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DOI
10.1016/j.foreco.2009.01.014.
ISSN
0378-1127
Rights
This article is published by Elsevier in Forest Ecology and Management (2009) by Crow, et al. All rights reserved.
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