Environmental stress and eutrophication in freshwater wetlands: evidence from carbon and nitrogen stable isotopes in cattail (Typha domingensis Pers.)  

作　　者：Ziye Zheng Yahong Xu Jianzhu Wang Yuncong Li Binhe Gu 

机构地区：[1]Engineering Research Center of Eco-environment in Three Gorges Reservoir Region,Ministry of Education,China Three Gorges University,Yichang 443002,China [2]Tropical Research and Education Center,University of Florida,18905 SW 280th St.Homestead,Gainesville,FL 33031,USA [3]Soil and Water Science Department,University of Florida,106 Newell Hall,Gainesville,FL 32611,USA

出　　处：《Ecological Processes》2019年第1期383-390,共8页生态过程（英文）

基　　金：from an Overseas Research collaboration grant(2018AHB020)funded by Hubei Province,China.

摘　　要：Background: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 andδ15N)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)<10μg L−1,transition sites with TP≥10μg L−1<20μg L−1 and impacted sites with TP≥20μg L−1 which differed in hydrology or habitats(marsh and canal).Results:Cattailδ13C 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.Conclusions:The different patterns for the changes inδ13C andδ15N 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 higherδ13C and lowerδ15N values.Findings from this study suggested thatδ13C in emerged macrophytes such as cattail can be used as an indicator for environmental stress whileδ15N is a robust indicator for wetland eutrophication.

关 键 词：CATTAIL EUTROPHICATION EVERGLADES Nutrient gradient Phosphorus enrichment Stable isotopes WETLANDS 

分 类 号：O57[理学—粒子物理与原子核物理]