TY - JOUR
T1 - Altitude effect on leaf wax carbon isotopic composition in humid tropical forests
AU - Wu, Mong Sin
AU - Feakins, Sarah J.
AU - Martin, Roberta E.
AU - Shenkin, Alexander
AU - Bentley, Lisa Patrick
AU - Blonder, Benjamin
AU - Salinas, Norma
AU - Asner, Gregory P.
AU - Malhi, Yadvinder
N1 - Funding Information:
Contributing authors are part of the Andes Biodiversity and Ecosystems Research Group ABERG (andesresearch.org), the Global Ecosystems Monitoring (GEM) network (gem.tropicalforests.ox.ac.uk) and the Amazon Forest Inventory Network RAINFOR (www.rainfor.org) research consortia. Field sampling: The field campaign was funded by grants to Y.M. from the UK Natural Environment Research Council (Grants NE/D01025X/1, NE/D014174/1). The research leading to these results has received funding from the European Research Council (Belgium) under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n. 321131 and 291585 (GEM-TRAITS and T-FORCES) as well as the Jackson Foundation to Y.M. and a John D. and Catherine T. MacArthur Foundation (US) grant to GA. GA and the spectranomics team were supported by the endowment of the Carnegie Institution for Science, and by the US National Science Foundation (DEB-1146206), supporting the taxonomic contributions to the project. Carnegie Airborne Observatory data collection, processing and analyses were funded solely by the John D. and Catherine T. MacArthur Foundation. The Carnegie Airborne Observatory is supported by the Avatar Alliance Foundation, John D. and Catherine T. MacArthur Foundation, Andrew Mellon Foundation, David and Lucile Packard Foundation, Mary Anne Nyburg Baker and G. Leonard Baker Jr., and William R. Hearst III (all US). BB acknowledges a NSF doctoral dissertation improvement grant (EF-1209287) and a NERC independent research fellowship (NE/M019160/1). Laboratory work at USC: This material is based upon work supported by the US National Science Foundation under Grant No. EAR-1227192 to S.F. Acknowledgment is made to the donors of the American Chemical Society Petroleum Research Fund (US) for partial support of this research (53747-ND2) to S.F. In Perú, we thank the Servicio Nacional de Áreas Naturales Protegidas por el Estado (SERNANP) and personnel of Manu and Tambopata National Parks for logistical assistance and permission to work in the protected areas. We also thank the Explorers’ Inn and the Pontifical Catholic University of Perú (PUCP), as well as Amazon Conservation Association for use of the Tambopata and Wayqecha Research Stations, respectively. Many researchers were involved in the field, in particular we would like to thank E. Cosio, W. Huaraca-Huasca and J. Huaman for advising on field logistics; tree climbers: C. Costas, D. Chacón, H. Ninatay; field project supervision: T. Boza, M. Raurau; species identification and basal area: W. Farfan, F. Sinca; leaf areas R.M. Castro, G. Rayme, A. Robles, Y. Choque and Y. Valdez. We thank USC lab assistants: C. Hua, K. McPherson, E. Rosca, A. Figueroa, T. Peters and J. Sunwoo. We thank Kate Freeman, Aaron Diefendorf and Josh West for helpful discussions.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017/6/1
Y1 - 2017/6/1
N2 - The carbon isotopic composition of plant leaf wax biomarkers is commonly used to reconstruct paleoenvironmental conditions. Adding to the limited calibration information available for modern tropical forests, we analyzed plant leaf and leaf wax carbon isotopic compositions in forest canopy trees across a highly biodiverse, 3.3 km elevation gradient on the eastern flank of the Andes Mountains. We sampled the dominant tree species and assessed their relative abundance in each tree community. In total, 405 sunlit canopy leaves were sampled across 129 species and nine forest plots along the elevation profile for bulk leaf and leaf wax n-alkane (C27–C33) concentration and carbon isotopic analyses (δ13C); a subset (76 individuals, 29 species, five forest plots) were additionally analyzed for n-alkanoic acid (C22–C32) concentrations and δ13C. δ13C values display trends of +0.87 ± 0.16‰ km−1 (95% CI, r2 = 0.96, p < 0.01) for bulk leaves and +1.45 ± 0.33‰ km−1 (95% CI, r2 = 0.94, p < 0.01) for C29 n-alkane, the dominant chain length. These carbon isotopic gradients are defined in multi-species sample sets and corroborated in a widespread genus and several families, suggesting the biochemical response to environment is robust to taxonomic turnover. We calculate fractionations and compare to adiabatic gradients, environmental variables, leaf wax n-alkane concentrations, and sun/shade position to assess factors influencing foliar chemical response. For the 4 km forested elevation range of the Andes, 4–6‰ higher δ13C values are expected for upland versus lowland C3 plant bulk leaves and their n-alkyl lipids, and we expect this pattern to be a systematic feature of very wet tropical montane environments. This elevation dependency of δ13C values should inform interpretations of sedimentary archives, as 13C-enriched values may derive from C4 grasses, petrogenic inputs or upland C3 plants. Finally, we outline the potential for leaf wax carbon isotopes to trace biomarker sourcing within catchments and for paleoaltimetry.
AB - The carbon isotopic composition of plant leaf wax biomarkers is commonly used to reconstruct paleoenvironmental conditions. Adding to the limited calibration information available for modern tropical forests, we analyzed plant leaf and leaf wax carbon isotopic compositions in forest canopy trees across a highly biodiverse, 3.3 km elevation gradient on the eastern flank of the Andes Mountains. We sampled the dominant tree species and assessed their relative abundance in each tree community. In total, 405 sunlit canopy leaves were sampled across 129 species and nine forest plots along the elevation profile for bulk leaf and leaf wax n-alkane (C27–C33) concentration and carbon isotopic analyses (δ13C); a subset (76 individuals, 29 species, five forest plots) were additionally analyzed for n-alkanoic acid (C22–C32) concentrations and δ13C. δ13C values display trends of +0.87 ± 0.16‰ km−1 (95% CI, r2 = 0.96, p < 0.01) for bulk leaves and +1.45 ± 0.33‰ km−1 (95% CI, r2 = 0.94, p < 0.01) for C29 n-alkane, the dominant chain length. These carbon isotopic gradients are defined in multi-species sample sets and corroborated in a widespread genus and several families, suggesting the biochemical response to environment is robust to taxonomic turnover. We calculate fractionations and compare to adiabatic gradients, environmental variables, leaf wax n-alkane concentrations, and sun/shade position to assess factors influencing foliar chemical response. For the 4 km forested elevation range of the Andes, 4–6‰ higher δ13C values are expected for upland versus lowland C3 plant bulk leaves and their n-alkyl lipids, and we expect this pattern to be a systematic feature of very wet tropical montane environments. This elevation dependency of δ13C values should inform interpretations of sedimentary archives, as 13C-enriched values may derive from C4 grasses, petrogenic inputs or upland C3 plants. Finally, we outline the potential for leaf wax carbon isotopes to trace biomarker sourcing within catchments and for paleoaltimetry.
KW - Altitude effect
KW - Amazon
KW - Andes
KW - Biomarker
KW - Carbon isotopes
KW - Leaf wax
KW - Peru
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U2 - 10.1016/j.gca.2017.02.022
DO - 10.1016/j.gca.2017.02.022
M3 - Article
AN - SCOPUS:85015370876
SN - 0016-7037
VL - 206
SP - 1
EP - 17
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -