Carbon isotopic composition of cypress trees from South Florida and changing hydrologic conditions

Anderson, William T.; Sternberg, L. O.; Pinzon, M. C.; Gann-Troxler, T.; Childers, Daniel L.; Duever, Michael J.

doi:10.1016/j.dendro.2005.07.006

Cited by 30 publications

(22 citation statements)

References 31 publications

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“…Though substantial, inter- and intra-specific differences in 13 C discrimination [3], [5], [7], [13] and variation across altitudinal and latitudinal gradients [9], [17], [18] have been overlooked in most iWUE studies. Global estimates of iWUE integrated over the past decades, without accounting for such variability, suggest that increases of the same magnitude with no significant differences occurred across biomes [8].…”

Section: Resultsmentioning

confidence: 99%

“…Conversely, if C i is low there is less discrimination against 13 C resulting in higher δ 13 C values. Regardless of growth rates or net changes in productivity, any change in carboxylation and/or stomatal conductance that alters C i /C a is recorded as a change in δ 13 C [12], which in the case of tree species that produce annual growth rings can be used to reconstruct physiological changes over long periods of time [11], [13]. Because atmospheric δ 13 C also varies over time, tree-rings must be analyzed in relation to atmospheric 13 C abundance at the moment of its assimilation.…”

Section: Methodsmentioning

confidence: 99%

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Explaining Global Increases in Water Use Efficiency: Why Have We Overestimated Responses to Rising Atmospheric CO2 in Natural Forest Ecosystems?

Silva

Horwáth

2013

PLoS ONE

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BackgroundThe analysis of tree-ring carbon isotope composition (δ13C) has been widely used to estimate spatio-temporal variations in intrinsic water use efficiency (iWUE) of tree species. Numerous studies have reported widespread increases in iWUE coinciding with rising atmospheric CO2 over the past century. While this could represent a coherent global response, the fact that increases of similar magnitude were observed across biomes with no apparent effect on tree growth raises the question of whether iWUE calculations reflect actual physiological responses to elevated CO2 levels.Methodology/ResultsHere we use Monte Carlo simulations to test if an artifact of calculation could explain observed increases in iWUE. We show that highly significant positive relationships between iWUE and CO2 occur even when simulated data (randomized δ13C values spanning the observed range) are used in place of actual tree-ring δ13C measurements. From simulated data sets we calculated non-physiological changes in iWUE from 1900 to present and across a 4000 m altitudinal range. This generated results strikingly similar to those reported in recent studies encompassing 22 species from tropical, subtropical, temperate, boreal and mediterranean ecosystems. Only 6 of 49 surveyed case studies showed increases in iWUE significantly higher than predicted from random values.Conclusions/SignificanceOur results reveal that increases in iWUE estimated from tree-ring δ13C occur independently of changes in 13C discrimination that characterize physiological responses to elevated CO2. Due to a correlation with CO2 concentration, which is used as an independent factor in the iWUE calculation, any tree-ring δ13C data set would inevitably generate increasing iWUE over time. Therefore, although consistent, previously reported trends in iWUE do not necessarily reflect a coherent global response to rising atmospheric CO2. We discuss the significance of these findings and suggest ways to distinguish real from artificial responses in future studies.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Explaining Global Increases in Water Use Efficiency: Why Have We Overestimated Responses to Rising Atmospheric CO2 in Natural Forest Ecosystems?

Silva

Horwáth

2013

PLoS ONE

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“…Among those, water‐tree relations are likely the factor with the highest impact (Zweifel et al ., ). In addition to tree ring size, δ 13 C isotope is a valid measure of the impact of climatic signals on tree physiology, as it is a measure of plants productivity and is correlated with the tree ring index (Anderson W. T. et al ., ), as well as with temperature, precipitation and plant's response to atmospheric CO 2 concentration (Treydte et al ., ).…”

Section: Resultsmentioning

confidence: 99%

“…Dendrochronological records were also analysed in order to investigate potential impacts of hydrological and climatic conditions on the ecosystem vegetative productivity and carbon assimilation. In particular, records for both tree rings sizes and δ 13 C isotope content were gathered for Pond Cypresses (Taxodium ascendens) in the C-111 basin in the Southeastern Everglades Marsh (Figure 1) for the period 1970-2000, using a database compiled by the Florida Coastal Everglades (Anderson et al, 2005).…”

Section: Flora and Fauna Datasetsmentioning

confidence: 99%

Demodulation of time series highlights impacts of hydrologic drivers on the Everglades ecosystem

et al. 2014

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In the context of climatic uncertainty and potential climatic change, incorporating climatic variability and change in eco‐hydrological analysis, as well as understanding the impact of such variability on ecosystems, is of crucial importance. The latter is particularly true for those complex ecosystems, such as wetlands, which cradle large varieties of species, many of which rare or endangered. Focusing on the Everglades wetlands, we investigate the presence of non‐stationary elements in the seasonal cycle of precipitation, temperature and stage level and examine their correlation and potential impact on the ecosystem's flora and fauna. To this aim, we revisit demodulation techniques and demonstrate their validity for the diagnosis of long‐term trends in the amplitude and phase of seasonal patterns of hydrologic series. We then analyse historical records of fauna and flora components of the Everglades in order to reveal potential relationships with hydrological trends. We observe that the seasonal patterns of all the time series analysed are non‐stationary. In addition, we observe that the amplitude of seasonal oscillations of all hydro‐climatic drivers is strongly correlated with anomalies in records of wading birds population and plant carbon assimilation. Copyright © 2014 John Wiley & Sons, Ltd.

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“…In this manner then, seasonal changes in precipitation and transitions through the drought cycle can be expected to significantly alter the isotopic composition of wetland macrophyte detritus entering the coastal zone. Anderson et al (2005) showed a positive correlation between precipitation and pond cypress isotopic composition in the freshwater Everglades, thus longer hydro-period in the upstream Everglades may lead to isotopic enrichment in particulate detritus. Salinity stress, though seeming to be the opposite of water stress associated with increases in freshwater hydro-period, may also induce decreases in stomatal conductance and ensuing isotopic enrichment ).…”

Section: Stable Isotopes Of Carbon and Nitrogenmentioning

confidence: 99%

Carbon and Nitrogen Stable Isotopic Patterns in South Florida Coastal Ecosystems: Modern and Paleoceanographic Perspectives

Evans¹

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Carbon isotopic composition of cypress trees from South Florida and changing hydrologic conditions

Cited by 30 publications

References 31 publications

Explaining Global Increases in Water Use Efficiency: Why Have We Overestimated Responses to Rising Atmospheric CO2 in Natural Forest Ecosystems?

Explaining Global Increases in Water Use Efficiency: Why Have We Overestimated Responses to Rising Atmospheric CO2 in Natural Forest Ecosystems?

Demodulation of time series highlights impacts of hydrologic drivers on the Everglades ecosystem

Carbon and Nitrogen Stable Isotopic Patterns in South Florida Coastal Ecosystems: Modern and Paleoceanographic Perspectives

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