scholarly journals Variations in Stable Carbon Isotope Composition and Leaf Traits ofPicea schrenkianavar.tianschanicaalong an Altitude Gradient in Tianshan Mountains, Northwest China

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Huiwen Zhang ◽  
Jianying Ma ◽  
Wei Sun ◽  
Fahu Chen
Keyword(s):  
Photosynthetic Capacity ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Leaf Traits ◽  
Northwest China ◽  
Tianshan Mountains ◽  
Stable Carbon ◽  
Altitude Gradient ◽  
Altitudinal Gradients ◽  
One Year

To understand the morphological and physiological responses of leaves to changes in altitudinal gradients, we examined ten morphological and physiological characteristics in one-year-old needles ofPicea schrenkianavar.tianschanicaat ten points along an altitudinal gradient from 1420 to 2300 m a.s.l. on the northern slopes of the Tianshan Mountains in northwest China. Our results indicated that LA, SD, LPC, and LKC increased linearly with increasing elevation, whereas leafδ13C, LNC, Chla + b, LDMC, LMA, and Nareavaried nonlinearly with changes in altitude. With elevation below 2100 m, LNC, Narea, and Chla + b increased, while LDMC and LMA decreased with increasing altitude. When altitude was above 2100 m, these properties showed the opposite patterns. Leafδ13C was positively correlated with Nareaand LNC and negatively correlated with SD and LA, suggesting that leafδ13C was indirectly controlled by physiological and morphological adjustments along altitudinal gradients. Based on the observed maximum values in LNC, Narea, Chla + b, and LA and the minimum values in LMA and LDMC at the elevation of 2100 m, suggesting higher photosynthetic capacity and greater potential for fast growth under superior optimum zone, we concluded that the best growing elevation forP. schrenkianavar.tianschanicain the Tianshan Mountains was approximately 2100 m.

When animals are not quite what they eat: diet digestibility influences 13C-incorporation rates and apparent discrimination in a mixed-feeding herbivore

2011 ◽  
Vol 89 (6) ◽  
pp. 453-465 ◽  
Author(s):  
Daryl Codron ◽  
Jacqui Codron ◽  
Matt Sponheimer ◽  
Stefano M. Bernasconi ◽  
Marcus Clauss
Keyword(s):  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Food Sources ◽  
Capra Hircus ◽  
Stable Carbon ◽  
Animal Tissues ◽  
Themeda Triandra ◽  
Low Protein ◽  
Medicago Sativa L ◽  
Discrimination Factors

The stable carbon isotope composition of animal tissues represents the weighted sum of the variety of food sources eaten. If sources differ in digestibility, tissues may overrepresent intake of more digestible items and faeces may overrepresent less digestible items. We tested this idea using whole blood and faeces of goats ( Capra hircus L., 1758) fed different food mixtures of C3 lucerne ( Medicago sativa L.) and C4 grass ( Themeda triandra Forssk.). Although blood and faecal δ13C values were broadly consistent with diet, results indicate mismatch between consumer and diet isotope compositions: both materials overrepresented the C3 (lucerne) component of diets. Lucerne had lower fibre digestibility than T. triandra, which explains the results for faeces, whereas underrepresentation of dietary C4 in blood is consistent with low protein content of the grass hay. A diet switch experiment revealed an important difference in 13C-incorporation rates across diets, which were slower for grass than lucerne diets, and in fact equilibrium states were not reached for all diets. Although more research is needed to link digestive kinetics with isotope incorporation, these results provide evidence for nonlinear relationships between consumers and their diets, invoking concerns about the conceptual value of “discrimination factors” as the prime currency for contemporary isotope ecology.

Factors affecting 13C/12C ratios of inland halophytes. I. Controlled studies on growth and isotopic composition of Puccinellia nuttalliana

1986 ◽  
Vol 64 (11) ◽  
pp. 2693-2699 ◽  
Author(s):  
Robert D. Guy ◽  
David M. Reid ◽  
H. Roy Krouse
Keyword(s):  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Isotope Analysis ◽  
Research Problem ◽  
Carbon Isotope Composition ◽  
Stable Carbon ◽  
Factors Affecting ◽  
Plant Parts ◽  
High Level ◽  
Puccinellia Nuttalliana

Studies on various factors affecting the growth and stable carbon isotope composition of the graminaceous C3 halophyte Puccinellia nuttalliana (Schultes) Hitch. were initiated as a step towards interpreting δ13C variations in nature. For isotope analysis, combustion at 900 °C resulted in higher CO2 yield than at 550 °C but did not affect δ13C values. Differences in δ13C between leaves of different insertion level were unimportant, but roots were about 1‰ more positive than shoots. Trends in δ13C with salinity were the same in all plant parts. Depressions of growth by NaCl or Na2SO4 were similar, but plants grown in Na2SO4 displayed a greater shift in δ13C relative to controls. Growth rates were affected more by salinity than were previously reported photosynthetic rates. At typical salinities, δ13C changed linearly with salinity. The supply of nitrate to stressed and unstressed plants had no important influence on δ13C. Growth in polyethylene glycol produced δ13C values consistent with a high level of stress. After a salinity step-up, changes in δ13C were complete within 10 days. During winter, data were found to be heavily influenced by unintentional, human-respired CO2 enrichment. This represents a potentially serious research problem in laboratories of temperate climes.

Tracing Carbon Isotope Variations in Lake Sediments Caused by Environmental Factors During the Past Century: A Case Study of Lake Tapeliai, Lithuania

Radiocarbon ◽  
2019 ◽  
Vol 61 (4) ◽  
pp. 885-903 ◽  
Author(s):  
Rūta Barisevičiūtė ◽  
Evaldas Maceika ◽  
Žilvinas Ežerinskis ◽  
Jonas Mažeika ◽  
Laurynas Butkus ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Humic Acids ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Hard Water ◽  
Lake Ecosystem ◽  
Past Century ◽  
Stable Carbon ◽  
Organic Fractions ◽  
Reservoir Age

ABSTRACTIn this study, we examined how land use and urbanization changes in adjacent areas affected biological productivity and carbon cycling in a lake ecosystem over 100 years and how these changes are reflected in carbon isotope variations. We performed radiocarbon (14C) activity and stable carbon isotope ratio analysis in two organic fractions: humin and humic acids of lake sediment. Additionally, we performed pigment and diatom analysis and determined the carbonate and organic matter (OM) content in sediments. Over the last century, the estimated 14C reservoir age in both sediment organic fractions varied from 1136 ± 112 yr to 5733 ± 122 yr. The increase in the reservoir age by 1175 ± 111 yr was related with higher inputs of pre-aged organic carbon and 14C depleted hard water due to the opening of the channel connecting two lakes. Nuclear weapons tests caused an increase in the reservoir age of up to 5421 ± 135 yr and 5733 ± 122 yr in humin and humic acids, respectively. 13C values in the humic acid fraction showed a tendency to decrease, depending on the content of autochthonous versus allochthonous OM in sediments, while changes in the sources of OM had a minor impact on the stable carbon isotope composition in the humin fraction.

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