N2-fixing tropical legume evolution: A contributor to enhanced weathering through the Cenozoic?

Dimitar Z. Epihov, Sarah A. Batterman, Lars O. Hedin, Jonathan R. Leake, Lisa M. Smith, David J. Beerling

Research output: Contribution to journalReview article

5 Scopus citations

Abstract

Fossil and phylogenetic evidence indicates legume-rich modern tropical forests replaced Late Cretaceous palm-dominated tropical forests across four continents during the early Cenozoic (58-42 Ma). Tropical legume trees can transform ecosystems via their ability to fix dinitrogen (N2) and higher leaf N compared with non-legumes (35-65%), but it is unclear howtheir evolutionary rise contributed to silicateweathering, the long-term sink for atmospheric carbon dioxide (CO2). Herewe hypothesize that the increasing abundance of N2-fixing legumes in tropical forests amplified silicate weathering rates by increased input of fixed nitrogen (N) to terrestrial ecosystems via interrelated mechanisms including increasing microbial respiration and soil acidification, and stimulating forest net primary productivity.We suggest the high CO2 early Cenozoic atmosphere further amplified legume weathering. Evolution of legumes with high weathering rates was probably driven by their high demand for phosphorus and micronutrients required for N2-fixation and nodule formation.

Original languageEnglish (US)
Article number20170370
JournalProceedings of the Royal Society B: Biological Sciences
Volume284
Issue number1860
DOIs
StatePublished - Aug 16 2017

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

Keywords

  • CO sequestration
  • Cenozoic
  • Legume trees
  • N-fixation
  • Rock weathering
  • Tropical forests

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