Background:Evaluation of carbon(C),nitrogen(N),and phosphorus(P)ratios in aquatic and terrestrial ecosystems can advance our understanding of biological processes,nutrient cycling,and the fate of organic matter(OM)in ...Background:Evaluation of carbon(C),nitrogen(N),and phosphorus(P)ratios in aquatic and terrestrial ecosystems can advance our understanding of biological processes,nutrient cycling,and the fate of organic matter(OM)in these ecosystems.Eutrophication of aquatic ecosystems can change the accumulation and decomposition of OM which can alter biogeochemical cycling and alter the base of the aquatic food web.This study investigated nutrient stoichiometry within and among wetland ecosystem compartments(i.e.,water column,flocculent,soil,and aboveground vegetation biomass)of two subtropical treatment wetlands with distinct vegetation communities.Two flow-ways(FWs)within the network of Everglades Stormwater Treatment Areas in south Florida(USA)were selected for this study.We evaluated nutrient stoichiometry of these to understand biogeochemical cycling and controls of nutrient removal in a treatment wetland within an ecological stoichiometry context.Results:This study demonstrates that C,N,and P stoichiometry can be highly variable among ecosystem compartments and between FWs.Power law slopes of C,N,and P within surface water floc,soil,and vegetation were significantly different between and along FWs.Conclusions:Assessment of wetland nutrient stoichiometry between and within ecosystem compartments suggests unconstrained stoichiometry related to P that conforms with the notion of P limitation in the ecosystem.Differences in N:P ratios between floc and soil suggest different pathways of organic nutrient accumulation and retention between FWs.Surface nutrient stoichiometry was highly variable and decoupled(or close to decoupled as indicated by<25%explained variation between parameters),in particular with respect to P.We hypothesize that decoupling may be the imprint of variability in inflow nutrient stoichiometry.However,despite active biogeochemical cycles that could act to restore nutrient stoichiometry along the FW,there was little evidence that such balancing occurred,as the degree of stochiometric decoupling in the water column did change with distance downstream.This information is only the beginning of a larger journey to understand stoichiometric processes within wetland ecosystems and how they relate to ecosystem function.展开更多
Introduction:The Florida Everglades has undergone significant ecological change spanning the continuum of disturbance to restoration.While the restoration effort is not complete and the ecosystem continues to experien...Introduction:The Florida Everglades has undergone significant ecological change spanning the continuum of disturbance to restoration.While the restoration effort is not complete and the ecosystem continues to experience short duration perturbations,a better understanding of long-term C dynamics of the Everglades is needed to facilitate new restoration efforts.This study evaluated temporal trends of different aquatic carbon(C)pools of the northern Everglades Protection Area over a 20-year period to gauge historic C cycling patterns.Dissolved inorganic C(DIC),dissolved organic C(DOC),particulate organic C(POC),and surface water carbon dioxide(pCO2(aq))were investigated between May 1,1994 and April 30,2015.Results:Annual mean concentrations of DIC,DOC,POC,and pCO2(aq)significantly decreased through time or remained constant across the Water Conservation Areas(WCAs).Overall,the magnitude of the different C pools in the water column significantly differed between regions.Outgassing of CO2 was dynamic across the Everglades ranging from 420 to 2001 kg CO2 year−1.Overall,the historic trend in CO2 flux from the marsh declined across our study area while pCO2(aq)largely remained somewhat constant with the exception of Water Conservation Area 2 which experienced significant declines in pCO2(aq).Particulate OC concentrations were consistent between WCAs,but a significantly decreasing trend in annual POC concentrations was observed.Conclusions:Hydrologic condition and nutrient inputs significantly influenced the balance,speciation,and flux of C pools across WCAs suggesting a subsidy-stress response in C dynamics relative to landscape scale responses in nutrient availability.The interplay between nutrient inputs and hydrologic condition exert a driving force on the balance between DIC and DOC production via the metabolism of organic matter which forms the base of the aquatic food web.Along the restoration trajectory as water quality and hydrology continues to improve,it is expected that C pools will respond accordingly.展开更多
基金sample collection and analysis was provided by the South Florida Water Management District(Contract#4600003031).
文摘Background:Evaluation of carbon(C),nitrogen(N),and phosphorus(P)ratios in aquatic and terrestrial ecosystems can advance our understanding of biological processes,nutrient cycling,and the fate of organic matter(OM)in these ecosystems.Eutrophication of aquatic ecosystems can change the accumulation and decomposition of OM which can alter biogeochemical cycling and alter the base of the aquatic food web.This study investigated nutrient stoichiometry within and among wetland ecosystem compartments(i.e.,water column,flocculent,soil,and aboveground vegetation biomass)of two subtropical treatment wetlands with distinct vegetation communities.Two flow-ways(FWs)within the network of Everglades Stormwater Treatment Areas in south Florida(USA)were selected for this study.We evaluated nutrient stoichiometry of these to understand biogeochemical cycling and controls of nutrient removal in a treatment wetland within an ecological stoichiometry context.Results:This study demonstrates that C,N,and P stoichiometry can be highly variable among ecosystem compartments and between FWs.Power law slopes of C,N,and P within surface water floc,soil,and vegetation were significantly different between and along FWs.Conclusions:Assessment of wetland nutrient stoichiometry between and within ecosystem compartments suggests unconstrained stoichiometry related to P that conforms with the notion of P limitation in the ecosystem.Differences in N:P ratios between floc and soil suggest different pathways of organic nutrient accumulation and retention between FWs.Surface nutrient stoichiometry was highly variable and decoupled(or close to decoupled as indicated by<25%explained variation between parameters),in particular with respect to P.We hypothesize that decoupling may be the imprint of variability in inflow nutrient stoichiometry.However,despite active biogeochemical cycles that could act to restore nutrient stoichiometry along the FW,there was little evidence that such balancing occurred,as the degree of stochiometric decoupling in the water column did change with distance downstream.This information is only the beginning of a larger journey to understand stoichiometric processes within wetland ecosystems and how they relate to ecosystem function.
文摘Introduction:The Florida Everglades has undergone significant ecological change spanning the continuum of disturbance to restoration.While the restoration effort is not complete and the ecosystem continues to experience short duration perturbations,a better understanding of long-term C dynamics of the Everglades is needed to facilitate new restoration efforts.This study evaluated temporal trends of different aquatic carbon(C)pools of the northern Everglades Protection Area over a 20-year period to gauge historic C cycling patterns.Dissolved inorganic C(DIC),dissolved organic C(DOC),particulate organic C(POC),and surface water carbon dioxide(pCO2(aq))were investigated between May 1,1994 and April 30,2015.Results:Annual mean concentrations of DIC,DOC,POC,and pCO2(aq)significantly decreased through time or remained constant across the Water Conservation Areas(WCAs).Overall,the magnitude of the different C pools in the water column significantly differed between regions.Outgassing of CO2 was dynamic across the Everglades ranging from 420 to 2001 kg CO2 year−1.Overall,the historic trend in CO2 flux from the marsh declined across our study area while pCO2(aq)largely remained somewhat constant with the exception of Water Conservation Area 2 which experienced significant declines in pCO2(aq).Particulate OC concentrations were consistent between WCAs,but a significantly decreasing trend in annual POC concentrations was observed.Conclusions:Hydrologic condition and nutrient inputs significantly influenced the balance,speciation,and flux of C pools across WCAs suggesting a subsidy-stress response in C dynamics relative to landscape scale responses in nutrient availability.The interplay between nutrient inputs and hydrologic condition exert a driving force on the balance between DIC and DOC production via the metabolism of organic matter which forms the base of the aquatic food web.Along the restoration trajectory as water quality and hydrology continues to improve,it is expected that C pools will respond accordingly.
