Diagenetic processes in the plant-soil system and their implications for palaeo-reconstruction
Abstract
Plant-derived organic matter in soils and peats comprises mixtures of biomolecular components that can act as 'biomarkers' for their vegetative provenance. Different plant communities are adapted to specific environmental conditions, so this approach can be used to investigate a variety of questions about land-use and climate change over a range of timescales. For example, the abundance and distribution of long-chain aliphatic compounds, that are relatively hydrophobic and resistant to microbial decomposition, are widely used as evidence of colonisation by different groups of plants in either natural or managed contemporary environments [1]. Natural abundance or artificial 13C-labelling of plants is used to provide additional evidence for plant inputs, and to determine rates of turnover of soil C pools using compound-specific stable isotope ratio mass spectrometry [2]. However, the application of molecular approaches to palaeovegetation reconstruction is still relatively rare. Biomarkers for different vegetation types are particularly important when diagenetic processes result in the loss of plant macrofossils. Lipid biomarkers are the most commonly used [3], and their δ13C values can be used to determine shifts in palaeoclimate using changes in the contribution of C3 and C4 plant-derived compounds [4]. Carbohydrates are the major components of plant biomass, but their potential as biomarkers is usually disregarded due to their perceived rapid decomposition. However, recently, we showed that carbohydrate compositional parameters of modern bog-forming plants showed strong correspondence with fossil plant abundances in a peat core from Kontolanrahka Bog, Finland [5]. Subsequent application of the carbohydrate proxy to similar cores from Bissendorfer Moor, Germany, and Butterburn Flow, UK, has shown its potential to explore plant inputs in anaerobic terrestrial environments. [1] Dungait JAJ, Docherty G, Straker V, Evershed RP, 2010a. Phytochem 71:415. [2] Dungait JAJ, Bol R, Lopez-Capel E, Bull ID, Chadwick D, Amelung W, Granger SJ, Manning DAC, Evershed RP, 2010b. Rapid Comms Mass Spectrom 24:495. [3] Bingham EM, McClymont EL, Väliranta M, Mauquoy D, Roberts Z, Chambers FM, Pancost RD, Evershed RP, 2010. Org Geochem 41:214. [4] Wurster CM, Bird MI, Bull ID, Creed F, Bryant C, Dungait JAJ, Paz V, 2010. Proc Nat Acad Sci 107:15508. [5] Jia GD, Dungait JAJ, Bingham EM, Väliranta M, Korhola A, Evershed RP, 2008. Org Geochem 39:1790.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.B13K..05D
- Keywords:
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- 0400 BIOGEOSCIENCES;
- 0420 BIOGEOSCIENCES / Biomolecular and chemical tracers;
- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0454 BIOGEOSCIENCES / Isotopic composition and chemistry