Imperial College London
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DrGarethRoberts

Faculty of Engineering, Department of Earth Science & Engineering

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 7363gareth.roberts

 
 
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Location

 

2.50Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Hilton:2013:10.5194/bgd-9-12593-2012,
author = {Hilton, RG and Galy, A and West, AJ and Hovius, N and Roberts, GG},
doi = {10.5194/bgd-9-12593-2012},
journal = {Biogeosciences Discussions},
pages = {1693--1705},
title = {Geomorphic control on the δ<sup>15</sup>N of mountain forest},
url = {http://dx.doi.org/10.5194/bgd-9-12593-2012},
volume = {10},
year = {2013}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Mountain forests are subject to high rates ofphysical erosion which can export particulate nitrogen fromecosystems. However, the impact of geomorphic processeson nitrogen budgets remains poorly constrained. We haveused the elemental and isotopic composition of soil and plantorganic matter to investigate nitrogen cycling in the mountainforest of Taiwan, from 24 sites with distinct geomorphic(topographic slope) and climatic (precipitation, temperature)characteristics. The organic carbon to nitrogen ratio of soilorganic matter decreased with soil 14C age, providing constrainton average rates of nitrogen loss using a mass balancemodel. Model predictions suggest that present day estimatesof nitrogen deposition exceed contemporary and historic nitrogenlosses. We found ∼ 6 ‰ variability in the stable isotopiccomposition (δ15N) of soil and plants which was not relatedto soil 14C age or climatic conditions. Instead, δ15N wassignificantly, negatively correlated with topographic slope.Using the mass balance model, we demonstrate that the correlationcan be explained by an increase in nitrogen loss bynon-fractioning pathways on steeper slopes, where physicalerosion most effectively removes particulate nitrogen. Publisheddata from forests on steep slopes are consistent withthe correlation. Based on our dataset and these observations,we hypothesise that variable physical erosion rates can significantlyinfluence soil δ15N, and suggest particulate nitrogenexport is a major, yet underappreciated, loss term in thenitrogen budget of mountain forests.
AU  - Hilton,RG
AU  - Galy,A
AU  - West,AJ
AU  - Hovius,N
AU  - Roberts,GG
DO  - 10.5194/bgd-9-12593-2012
EP  - 1705
PY  - 2013///
SN  - 1810-6277
SP  - 1693
TI  - Geomorphic control on the δ<sup>15</sup>N of mountain forest
T2  - Biogeosciences Discussions
UR  - http://dx.doi.org/10.5194/bgd-9-12593-2012
UR  - http://hdl.handle.net/10044/1/49552
VL  - 10
ER  -
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