Strong correspondence between nitrogen isotope composition of foliage and chlorin across a rainfall gradient: Implications for paleo-reconstruction of the nitrogen cycle

Sara K.E. Goulden, Naohiko Ohkouchi, Katherine H. Freeman, Yoshito Chikaraishi, Nanako O. Ogawa, Hisami Suga, Oliver Chadwick, Benjamin Z. Houlton

Research output: Contribution to journalArticlepeer-review

Abstract

Nitrogen (N) availability influences patterns of terrestrial productivity and global carbon cycling, imparting strong but poorly resolved feedbacks on Earth's climate system. Central questions concern the timescale of N cycle response to elevated CO2 concentration in the atmosphere and whether availability of this limiting nutrient increases or decreases with climate change. Nitrogen isotopic composition of bulk plant leaves provides information on large-scale patterns of N availability in the modern environment. Here we examine the utility of chlorins, degradation products of chlorophyll, hypothesized to persist in soil subsequent to plant decay, as proxies for reconstructing past plant δ15N. Specifically, we test the hypothesis that δ15N of plant leaves (δ15Nleaf) is recorded in δ15N of pheophytin a (δ15Npheo) along the leaf-litter-soil continuum across an array of ecosystem climate conditions and plant functional types (C3, C4, legumes, and woody plants). The δ15N of live foliage and bulk soil display marked declines with increasing rainfall, consistent with past studies in Hawaii and patterns worldwide.We find measurable chlorin concentrations along soil-depth profiles at all sites, with pheophytin a present in amounts required for isotopic analysis (> 10 nmol). δ15Npheo in leaves, litter, and soil track δ15Nleaf of plant leaves. We find potential for δ15Npheo records from soil to provide proxy information on δ15Nleaf

Original languageEnglish (US)
Article numberbg-16-3869-2019
Pages (from-to)3869-3882
Number of pages14
JournalBiogeosciences
Volume16
Issue number19
DOIs
StatePublished - Oct 8 2019

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes

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