Decline in Ecosystem δ13C and Mid-Successional Nitrogen Loss in a Two-Century Postglacial Chronosequence

• Main Authors: Malone, Edward, T., Abbott, Benjamin, W., Klaar, Megan, J., Kidd, Chris, Sebilo, Mathieu, Milner, Alexander, M., Pinay, Gilles
• Other Authors: University of Birmingham Birmingham, University of Exeter, Brigham Young University (BYU), University of Leeds, Earth Science System Interdisciplinary Center College Park (ESSIC), College of Computer, Mathematical, and Natural Sciences College Park, University of Maryland College Park, University of Maryland System-University of Maryland System-University of Maryland College Park, University of Maryland System-University of Maryland System, Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris), Institut National de la Recherche Agronomique (INRA)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), University of Alaska Fairbanks (UAF), RiverLy - Fonctionnement des hydrosystèmes, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: primary succession; nitrification; denitrification; soil; foliar; 13 C; 15 N; Glacier Bay; water use efficiency; nutrient retention theory; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SDV.EE.ECO]Life Sciences [q-bio]/Ecology; environment/Ecosystems; glacier; Alaska
• Online Access: https://hal.sorbonne-universite.fr/hal-01950026; https://hal.sorbonne-universite.fr/hal-01950026/document; https://hal.sorbonne-universite.fr/hal-01950026/file/Malone2018_Article_DeclineInEcosystem%CE%9413CAndMid-S.pdf

International audience Uncertainty about controls on long-term carbon (C) and nitrogen (N) balance, turnover, and isotopic composition currently limits our ability to predict ecosystem response to disturbance and landscape change. We used a two-century, postglacial chronosequence in Glacier Bay, Alaska, to explore the influence of C and N dynamics on soil and leaf stable isotopes. C dynamics were closely linked to soil hydrology, with increasing soil water retention during ecosystem development resulting in a linear decrease in foliar and soil δ13C, independent of shifts in vegetation cover and despite constant precipitation across sites. N dynamics responded to interactions among soil development, vegetation type, microbial activity, and topography. Contrary to the predictions of nutrient retention theory, potential nitrification and denitrification were high, relative to inorganic N stocks, from the beginning of the chronosequence, and gaseous and hydrological N losses were highest at mid-successional sites, 140–165 years since deglaciation. Though leaching of dissolved N is considered the predominant pathway of N loss at high latitudes, we found that gaseous N loss was more tightly correlated with δ15N enrichment. These results suggest that δ13C in leaves and soil can depend as much on soil development and associated water availability as on climate and that N availability and export depend on interactions between physical and biological state factors.