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Limitation of lignin derivatives as biomarkers of land derived organic matter in the coastal marine sediments

100%
Pempkowiak J.
Oceanologia
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2020
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tom 62
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nr 3
2

Stable carbon and nitrogen isotopes reveal the food diet of Tibetan antelope Pantholops hodgsonii (Abel 1826) in Kekexili Nature Reserve (China)

84%
Sun P., Yu H.-H., Zhao X.-Q., Wang D.-H.
Polish Journal of Ecology
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2013
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tom 61
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nr 2
The stable isotope technique has been widely used to infer the dietary ecology of a range of animal species. The δ¹³C technique provides a valuable tool for researchers when designing pastures for dual environmental and production purposes. Tibetan antelope, Pantholops hodgsoni (chiru), is endemic species to the high-altitude Qinghai-Tibet Plateau of western China – Kekexili Nature Reserve area. The aim of this study was to identify the food diet of Tibetan antelope among plants with C₃ and C₄ photosynthetic pathways. Faeces and plant samples were collected at the Kekexili Nature Reserve (KNR, 34°19’ ~ 36°16’N, 89°25’ ~94°05’E) in Qinghai Province, China. Stable isotope values of carbon and nitrogen of faeces and plant samples were measured under EAMS (element-analysis meter and spectrometer) conditions. Enrichment and food content ratio were calculated according to previous research methods to determine the relative importance of plant sources in the food diet of Tibetan antelopes. The results indicate that faecal samples provided the most convenient and uninjurious sources to predict the food diet and that C₃ plants were selected as the food by chiru. Dualisotope multiple-source mixing model suggested that the food content of antelope is including Gramineae, Cyperaceae, Compositae, Leguminosae, and Cruciferae. An understanding of what chiru selects allows for development of appropriate grazing and protecting strategies, especially in fragile ecosystem. According to our knowledge, this is the first essay to reveal the food diet of chiru with stable isotope analysis method.
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Ecophysiology of horse chestnut [Aesculus hippocastanum L.] in degraded and restored urban sites

84%
Oleksyn J., Kloeppel D. B., Lukasiewicz S., Karolewski P., Reich P. B.
Polish Journal of Ecology
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2007
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tom 55
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nr 2
We explored changes in growth, phenology, net CO₂ assimilation rate, water use efficiency, secondary defense compounds, substrate and foliage nutrient concentration of a degraded urban horse chestnut (Aesculus hippocastanum L.) site restored for three years using mulching (tree branches including foliage) and fertilization (primarily nitrogen addition). Prior to restoration, this site was characterized by high pH (ca. 8), low foliage and substrate N, and high Na and Cl concentration. Our data indicated that in untreated plots NaCl used for road deicing is the decisive factors that may be responsible for the decrease of foliar N concentration (via a reduction in NO₃⁻ uptake), for the decrease in photosynthesis (through high concentrations of Na and Cl in the leaves) and for increased senescence of the leaves. After three years of treatment, total nitrogen concentration in substrate increased by 3- to 4-fold and calcium concentration decreased by more than 50% in relation to pretreatment levels. Treatment significantly increased seed production (from less than 12 to more than 100 seeds per tree), individual leaf mass (from 1.8 to 3.3 g/leaf), CO₂ assimilation rate (by 21 to 30 %), improved leaf C:N ratio, and increased foliage life span by as much as six weeks. The beginning of leaf fall in untreated control trees started in midJuly and those of mulched and fertilized trees in late October. Applied treatment also eliminated visible symptoms of leaf damage due to high sodium and chlorine levels, indicating the possible role of other factors in the development of necroses. After three years of treatment, pH of most degraded plots declined from 8.2 to 7.8. That decline was accompanied by an increase in foliar Zn, Cu, and Pb concentration in the mulched and fertilized plants. In addition, treatment lowered foliage phenolics making these plants potentially more vulnerable to insect herbivory. Our study indicates that stable carbon isotope discrimination is of little value as an indicator of cumulative salinity and urban environment stress in A. hippocastanum due to pronounced differences in leaf phenology and ontogeny. The results of our study show that street tree recovery can take as little as two to three years after application of fertilization and mulching.
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