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| Titel |
Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration |
| VerfasserIn |
E. M. Stacy, S. C. Hart, C. T. Hunsaker, D. W. Johnson, A. A. Berhe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 16 ; Nr. 12, no. 16 (2015-08-17), S.4861-4874 |
| Datensatznummer |
250118063
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| Publikation (Nr.) |
 copernicus.org/bg-12-4861-2015.pdf |
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| Zusammenfassung |
| Lateral movement of organic matter (OM) due to erosion is now considered an
important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet
most published studies on the role of erosion focus on agricultural or
grassland ecosystems. To date, little information is available on the rate
and nature of OM eroded from forest ecosystems. We present annual sediment
composition and yield, for water years 2005–2011, from eight catchments in
the southern part of the Sierra Nevada, California. Sediment was compared to
soil at three different landform positions from the source slopes to
determine if there is selective transport of organic matter or different
mineral particle size classes. Sediment export varied from 0.4 to 177 kg ha−1,
while export of C in sediment was between 0.025 and 4.2 kg C ha−1 and
export of N in sediment was between 0.001 and 0.04 kg N ha−1. Sediment
yield and composition showed high interannual variation.
In our study catchments, erosion laterally mobilized OM-rich litter material
and topsoil, some of which enters streams owing to the catchment topography
where steep slopes border stream channels. Annual lateral sediment export
was positively and strongly correlated with stream discharge, while C and N
concentrations were both negatively correlated with stream discharge; hence,
C : N ratios were not strongly correlated to sediment yield. Our results
suggest that stream discharge, more than sediment source, is a primary
factor controlling the magnitude of C and N export from upland forest
catchments. The OM-rich nature of eroded sediment raises important questions
about the fate of the eroded OM. If a large fraction of the soil organic
matter (SOM) eroded from
forest ecosystems is lost during transport or after deposition, the
contribution of forest ecosystems to the erosion-induced C sink is likely to
be small (compared to croplands and grasslands). |
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