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Environmental stress and eutrophication in freshwater wetlands: evidence from carbon and nitrogen stable isotopes in cattail (Typha domingensis Pers.)
Ecological Processes ( IF 4.8 ) Pub Date : 2019-08-06 , DOI: 10.1186/s13717-019-0186-4
Ziye Zheng , Yahong Xu , Jianzhu Wang , Yuncong Li , Binhe Gu

Florida’s Everglades is a vast freshwater peatland that has been impacted by the alterations of hydrological pattern and water quality which led to changes in plant species composition and biodiversity. In this study, carbon and nitrogen stable isotopes (δ13C and δ15N) in cattail (Typha domingensis) are evaluated as indicators of environmental changes in the Everglades wetlands along nutrient and hydrological gradients represented by reference sites with total phosphorus (TP) < 10 μg L−1, transition sites with TP ≥ 10 μg L−1 < 20 μg L−1 and impacted sites with TP ≥ 20 μg L−1 which differed in hydrology or habitats (marsh and canal). Cattail δ13C values decreased significantly from reference (–24.1‰), transition (–26.8‰) to the impacted sites (–28.2‰). In contrast, δ15N values increased significantly from reference (–5.2‰), transition (2.4‰) to the impacted site (5.9‰). In response to a poor hydrological condition, cattail in marsh area displayed 13C enrichment (–26.0‰) and 15N depletion (0.2‰). By contrast, cattail grown in the canal sites with favorable hydropattern displayed 13C depletion (–27.6‰) and 15N enrichment (5.9‰) from the canal sites with more favorable hydrological condition. The different patterns for the changes in δ13C and δ15N in cattail suggested that increased nutrients led to increased stomatal conductance and 13C fractionation during carbon uptake and decreased 15N fractionation with increasing nitrogen demand while poor hydrological condition coupled with low nutrients led to reduced plant growth indicated by higher δ13C and lower δ15N values. Findings from this study suggested that δ13C in emerged macrophytes such as cattail can be used as an indicator for environmental stress while δ15N is a robust indicator for wetland eutrophication.

中文翻译:

淡水湿地的环境胁迫和富营养化:香蒲中碳和氮稳定同位素的证据(香蒲(Typha domingensis)人)

佛罗里达的大沼泽地是一个广阔的淡水泥炭地,受到水文模式和水质变化的影响,导致植物物种组成和生物多样性发生变化。在这项研究中,香蒲(香蒲(Typha domingensis))的碳和氮稳定同位素(δ13C和δ15N)被评估为大沼泽地湿地沿养分和水文梯度(以总磷(TP)<10μgL为参考点)表示的环境变化的环境指标-1,TP≥10μgL-1 <20μgL-1的过渡点和TP≥20μgL-1的受影响点,其水文或生境(沼泽和运河)不同。香蒲的δ13C值从参考值(–24.1‰),过渡区(–26.8‰)到受影响部位(–28.2‰)显着下降。相反,δ15N值相对于参考值(–5.2‰)和跃迁值显着增加(2。4‰)移至受影响的地点(5.9‰)。为了应对恶劣的水文条件,沼泽区的香蒲显示出13 C富集(–26.0‰)和15N耗尽(0.2‰)。相比之下,在具有良好水文模式的运河场中生长的香蒲从水文条件更为有利的运河场中表现出13C损耗(–27.6‰)和15N富集(5.9‰)。香蒲中δ13C和δ15N变化的不同模式表明,养分增加会导致碳吸收过程中气孔导度和13C分馏增加,氮素需求增加会导致15N分馏减少,而水文条件差加上养分含量低会导致植物生长减少,较高的δ13C和较低的δ15N值。
更新日期:2019-08-06
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