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Stable carbon isotope as a signal index for monitoring grassland degradation.

ABSTRACT: Grassland degradation due to overgrazing is common in many areas of the world. This study analyzed the potential of the stable carbon isotope (?(13)C) value as a structural microcosmic index to monitor processes of grassland degradation. The ?(13)C values of plant leaves, roots and soils in non-grazed (NG) and over-grazed (OG) grassland were measured from samples collected from the seven types of grassland in China. We found that the leaf ?(13)C values of palatable species (?(13)Cleaf) and root ?(13)C values (?(13)Croot) in OG grasslands were reduced compared with those from NG grasslands. Furthermore, the ?(13)Cleaf and ?(13)Csoil were positive correlation with elevation and latitude, ?(13)Croot was negative correlation with them at high altitude (3000~5000m), and ?(13)Croot and ?(13)Csoil were negative correlation with them at low altitude (0~2000m), respectively. Consequently, tracing of the ?(13)C variations in grassland ecosystem can provide a powerful tool to evaluate the degree of grassland degradation.

SUBMITTER: Yao H

PROVIDER: S-EPMC4985657 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Stable carbon isotope as a signal index for monitoring grassland degradation.

Yao Hongyun H Wilkes Andreas A Zhu Guodong G Zhang Hongdan H Liu Xiaojuan X Dan Ding Zhai Xiajie X Tang Shiming S Chen Qing Q Zhang Yujuan Y Huang Ding D Wang Chengjie C

Scientific reports 20160816

Grassland degradation due to overgrazing is common in many areas of the world. This study analyzed the potential of the stable carbon isotope (δ(13)C) value as a structural microcosmic index to monitor processes of grassland degradation. The δ(13)C values of plant leaves, roots and soils in non-grazed (NG) and over-grazed (OG) grassland were measured from samples collected from the seven types of grassland in China. We found that the leaf δ(13)C values of palatable species (δ(13)Cleaf) and root ...[more]

PMID: 27527910

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Project description:BackgroundAn objective measure of added sugar (AS) and sugar-sweetened beverage (SSB) intake is needed. The δ(13)C value of finger-stick blood is a novel validated biomarker of AS/SSB intake; however, nonsweetener corn products and animal protein also carry a δ(13)C value similar to AS sources, which may affect blood δ(13)C values. The δ(15)N value of blood has been proposed as a "correction factor" for animal protein intake.ObjectivesThe objectives were to 1) identify foods associated with δ(13)C and δ(15)N blood values, 2) determine the contribution of nonsweetener corn to the diet relative to AS intake, and 3) determine if the dual-isotope model (δ(13)C and δ(15)N) is a better predictor of AS/SSB intake than δ(13)C alone.MethodsA cross-sectional sample of southwest Virginian adults (n = 257; aged 42 ± 15 y; 74% overweight/obese) underwent dietary intake assessments and provided finger-stick blood samples, which were analyzed for δ(13)C and δ(15)N values by using natural abundance stable isotope mass spectrometry. Statistical analyses included ANOVAs, paired-samples t tests, and multiple linear regressions.ResultsThe mean ± SD daily AS intake was 88 ± 59 g and nonsweetener corn intake was 13 ± 13 g. The mean δ(13)C value was -19.1 ± 0.9‰, which was significantly correlated with AS and SSB intakes (r = 0.32 and 0.39, respectively; P ≤ 0.01). The δ(13)C value and nonsweetener corn intake and the δ(15)N value and animal protein intake were not correlated. AS intake was significantly greater than nonsweetener corn intake (mean difference = 76.2 ± 57.2 g; P ≤ 0.001). The δ(13)C value was predictive of AS/SSB intake (β range: 0.28-0.35; P ≤ 0.01); however, δ(15)N was not predictive and minimal increases in R(2) values were observed when the δ(15)N value was added to the model.ConclusionsThe data do not provide evidence that the dual-isotope method is superior for predicting AS/SSB intakes within a southwest Virginian population. Our results support the potential of the δ(13)C value of finger-stick blood to serve as an objective measure of AS/SSB intake. This trial was registered at clinicaltrials.gov as NCT02193009.

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Stable carbon isotope as a signal index for monitoring grassland degradation.

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Stable carbon isotope as a signal index for monitoring grassland degradation.

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