Stable isotope characteristics across narrow savanna/woodland ecotones in Wolfe Creek Meteorite Crater, Western Australia

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• 作者：Matthew J. Wooller ; Beverly J. Johnson ; Andrew Wilkie and Marilyn L. Fogel
• 关键词：Carbon ; Nitrogen ; C3 ; C4 ; Plants
• 刊名：Oecologia
• 出版年：2005
• 出版时间：August 2005
• 年：2005
• 卷：145
• 期：1
• 页码：100-112
• 全文大小：704 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Ecology
  Plant Sciences
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1432-1939

文摘

The stable isotopic composition (δ13C) of sediments from lakes are frequently analyzed to reconstruct the proportion of the regional vegetation that used either the C₃ or C₄ photosynthetic pathways, often without conducting a detailed survey of the current local vegetation. We performed a study on the modern vegetation composition within the Wolfe Creek Meteorite Crater to complement our future paleoecological investigation of the crater. A bull’s-eye pattern exists where C₄ grasses dominate an outer ring and salt tolerant species, including shrubs, herbs, chenopods, and halophytic algae, dominate the inner pan of the crater. The ecotone between the inner and outer zones is narrow and occupied by tall (>7 m) Acacia ampliceps, with some C₄ grasses in the understory. Along with the highest water table and most saline soils the center of the crater has C₃ plants present with the highest δ13C and δ15N values. The range of δ13C and δ15N values from the analysis of surface soil organic matter (OM) was much smaller compared with the range of values from plant materials implying that either: (1) the current plant OM has not yet been integrated into the soils, or (2) processes within the soil have acted to homogenize isotopic variability within the crater. The application of a two end member mixing model to calculate %C₄ and %C₃ biomass from the δ13C of surface soil OM was complicated by: (1) the crater containing both a dry habitat with C₄ grasses and a central pan with C₄ halophytic plants and, (2) the large variation in the δ13C of the plants and soil OM.