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Environmental assessment of vegetation and hydrological conditions in Everglades freshwater marshes using multiple geochemical proxies

机译：利用多种地球化学指标评价大沼泽地淡水沼泽中植被和水文条件的环境

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摘要

Paleoecological reconstructions of environmental changes provide important information for Everglades restoration targets. Traditionally this has been achieved using a combination of biological and physical indicators. However, as microfossils may be sporadically abundant in Everglades soils, organic geochemical methods can provide information at the molecular level. To reconstruct vegetation trends over the last century, soil cores from Shark to Taylor Sloughs, the primary flowpaths of the southern Everglades, were examined using several geochemical proxies. The n-alkane derived biomarker Paq effectively distinguished organic inputs from sawgrass and slough habitats. Other proxies examined include Kaurenes, cyclic diterpenoids unique to sawgrass roots; biomarkers of algae (highly branched isoprenoids (C_(20)HBIs) and Bot-ryococcenes); lignin phenols as vascular plant indicators; and macrofossils. At all sites, soil profiles from sawgrass marshes showed vegetation had shifted over the last 100 years, from sloughs to sawgrass-dominated marshes, reflecting decreased water levels (shorter hydroperiods) induced by water management. Paleo-assessments of modern sloughs, however, indicate these habitats remained deeper water habitats throughout the period of record, though shifts toward shorter hydroperiod vegetation were observed. In Taylor Slough, evidence of increasingly dry conditions in sloughs was confirmed by seed inputs from woody species. At 3 of the 5 sites, recent increases in C_(20)HBIs and Botryococcene concentrations indicated greater periphyton abundance, coincidental with increased mineral concentrations observed in surface waters during the mid-20th Century. Bulk proxies such as organic content and carbon:nitrogen ratios also supported findings of changes in relative contributions of microbial and higher plants in this ecosystem.
机译：环境变化的古生态重建为大沼泽地恢复目标提供了重要信息。传统上，这是通过结合生物学和物理指标来实现的。但是，由于大沼泽地土壤中的微化石可能是零星的，因此有机地球化学方法可以提供分子水平的信息。为了重建上个世纪的植被趋势，使用了几种地球化学代理对从鲨鱼到南部大沼泽地主要流动路径泰勒斯劳斯的土壤核心进行了研究。从正构烷烃衍生的生物标记Paq有效地区分了锯齿草和泥沼栖息地的有机物。检查的其他代理包括Kaurenes，锯齿草根特有的环状二萜；藻类的生物标志物（高度分支的类异戊二烯（C_（20）HBIs）和bot-ryococcenes）；木质素酚作为维管束的指标；和大型化石。在所有地点，锯草沼泽的土壤剖面表明，在过去的100年中，植被已经从低谷转变为以锯草为主的沼泽，这反映了水管理引起的水位下降（较短的水文期）。然而，对现代泥沼的古评估表明，尽管观察到向较短的水生周期植被转移，但这些生境在整个记录期间仍为较深的水生境。在泰勒泥沼中，来自木本物种的种子投入证实了泥沼中干燥状况日益严重的证据。在这5个地点中的3个，最近的C_（20）HBIs和Botryococcene浓度增加表明周围植物的丰度更高，这与20世纪中叶在地表水中观察到的矿物质浓度增加同时发生。诸如有机物含量和碳：氮比例之类的大量代理也支持了该生态系统中微生物和高等植物相对贡献的变化发现。

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  • 来源
    《Aquatic Sciences》 |2015年第2期|271-291|共21页
  • 作者

    Colin J. Saunders; Min Gao; Rudolf Jaffe;

  • 作者单位

    Everglades Systems Assessment, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, FL 33406, USA;

    Environmental Geochemistry Group, Southeast Environmental Research Center (SERC) and Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA;

    Environmental Geochemistry Group, Southeast Environmental Research Center (SERC) and Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA;

  • 收录信息 美国《科学引文索引》(SCI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Everglades; Molecular; Biomarkers; Macrofossils; Paleoecology; Hydrology;

    机译：大沼泽地分子;生物标志物;大化石;古生态学水文;

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