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Terrestrial pyrogenic carbon export to fluvial ecosystems: lessons learned from the White Nile watershed of East Africa

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Title Terrestrial pyrogenic carbon export to fluvial ecosystems: lessons learned from the White Nile watershed of East Africa
 
Creator Guerena DT
Lehmann J
Walter T
Enders A
Neufeldt, Henry
Odiwuor H
Biwott H
Recha, John W.M.
Shepherd K
Barrios, E.
Wurster C
 
Subject agriculture
natural resource management
carbon loss
carbon cycling
 
Description Pyrogenic carbon (PyC) is important because of its role in the global organic C (OC) cycle and in modifying soil properties. However, our understanding of PyC movement from terrestrial to fluvial ecosystems is not robust. This study examined (i)whether erosion or subsurface transport wasmore important for PyC export from headwaters, (ii) whether PyC was exported preferentially to total OC (TOC), and (iii) whether themovement of PyC from terrestrial to aquatic ecosystems provides an explanation for the coupling of PyC and non-PyC observed in rivers at a global scale. In the Guineo-Congolian highland forest region of western Kenya, duplicate catchments with sizes of 1–12 ha were equipped with stream gauges in primary forest and adjacent mixed agricultural landscapes that were cleared by fire 10, 16, or 62 years before. Stream water samples were taken weekly throughout 1 year and compared with runoff to assess PyC movement. Additional stream samples were taken fromall major tributaries of theWhite Nile watershed of Lake Victoria. PyC was not found to be preferentially eroded relative to TOC or non-PyC, as topsoil (0–0.15m) PyC concentrations (6.3 ± 0.3% of TOC; means and standard errors) were greater than runoff sediment (1.9 ± 0.4%) and dissolved PyC concentrations (2.0 ± 0.4%, n= 252). In addition, PyC proportions in eroded sediment were lower than and uncorrelated (r2=0.04; P= 0.14) with topsoil PyC. An enrichment of PyC was found with depth in the soil, from 6.3 ± 0.3% of TOC in the topsoil (0–0.15 m) to 12.3 ± 0.3% of TOC at 1–2m. Base flow PyC proportions of TOC correlated well with subsoil PyC (r2=0.57; P0.05). Similar PyC proportions were found in the studied headwater streams (2.7 ± 0.2%), their downstream inflow into Lake Victoria (3.7%), the other ninemajor rivers into Lake Victoria (4.9 ± 0.8%), and its outflow into the White Nile (1.1%). A strong positive correlation between dissolved PyC and non-PyC (r2 = 0.91; P
 
Date 2015-11
2015-11-12T12:10:19Z
2015-11-12T12:10:19Z
 
Type Journal Article
 
Identifier Guerena DT, Lehmann J, Walter T, Enders A, Neufeldt H, Odiwuor H, Biwott H, Recha J, Shepherd K, Barrios E, Wurster C. 2015. Terrestrial pyrogenic carbon export to fluvial ecosystems: lessons learned from the White Nile watershed of East Africa. Global Biogeochemical Cycles 29.
0886-6236
https://hdl.handle.net/10568/68920
EA_CSV
https://doi.org/10.1002/2015GB005095
 
Language en
 
Rights Copyrighted; all rights reserved
Open Access
 
Publisher Wiley
 
Source Global Biogeochemical Cycles