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1.
We measured the carbon and oxygen isotopic composition of stem cellulose of Pinus sylvestris, Picea abies, Fagus sylvatica and Fraxinus excelsior. Several sites along a transect of a small valley in Switzerland were selected which differ in soil moisture conditions. At every site, six trees per species were sampled, and a sample representing a mean value for the period from 1940 to 1990 was analysed. For all species, the mean site δ13C and δ18O of stem cellulose are related to the soil moisture availability, whereby higher isotope ratios are found at drier sites. This result is consistent with isotope fractionation models when assuming enhanced stomatal resistance (thus higher δ13C of incorporated carbon) and increased oxygen isotope enrichment in the leaf water (thus higher δ18O) at the dry sites. δ18 O-δ13C plots reveal a linear relationship between the carbon and oxygen isotopes in cellulose. To interpret this relationship we developed an equation which combines the above-mentioned fractionation models. An important new parameter is the degree to which the leaf water enrichment is reflected in the stem cellulose. In the combined model the slope of the δ18O-δ13C plot is related to the sensitivity of the pi/pa of a plant to changing relative humidity. 相似文献
2.
Gut contents of sand goby Pomatoschistus minutus showed higher C and N isotope values than the food before consumption. This enrichment was more pronounced in the hindgut than in the foregut, probably because of preferential assimilation of 12 C and 14 N along the gastro-intestinal tract. The results indicated that the shift towards higher values in the alimentary canal occurs in the first 2 h after feeding. 相似文献
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Seasonal variation in δ13C and δ18O of cellulose (δ13Cc and δ18Oc) was measured within two annual rings of Pinus radiata growing at three sites in New Zealand. In general, both δ13Cc and δ18Oc increased to a peak over summer. The three sites differed markedly in annual water balance, and these differences were reflected in δ13Cc and δ18Oc. Average δ13Cc and δ18Oc from each site were positively related, so that the driest site had the most enriched cellulose. δ13Cc and δ18Oc were also related within each site, although both the slope and the closeness of fit of the relationship varied between sites. Supporting the theory, the site with the lowest average relative humidity also had the greatest change in δ18Oc‰ change in δ13Cc. Specific climatic events, such as drought or high rainfall, were recorded as a peak or a trough in enrichment, respectively. These results suggest that seasonal and between‐site variation in δ13Cc and δ18Oc are driven by the interaction between variation in climatic conditions and soil water availability, and plant response to this variation. 相似文献
5.
J.P. Ferrio M.A. Mateo J. Bort O. Abdalla J. Voltas & J.L. Araus 《The Annals of applied biology》2007,150(2):207-215
Stable carbon isotope composition (δ13 C) of dry matter has been widely investigated as a selection tool in cereal breeding programmes. However, reports on the possibilities of using stable oxygen isotope composition (δ18 O) as a yield predictor are very scarce and only in the absence of water stress. Indeed, it remains to be tested whether changes in phenology and stomatal conductance in response to water stress overrule the use of either δ13 C or δ18 O when water is limited. To answer this question, a set of 24 genotypes of bread wheat ( Triticum aestivum ) were assayed in two trials with different levels of deficit irrigation and a third trial under rainfed conditions in a Mediterranean climate (northwest Syria). Grain yield (GY) and phenology (duration from planting to anthesis and from anthesis to maturity) were recorded, and the δ13 C and δ18 O of grains were analysed to assess their suitability as GY predictors. Both δ13 C and δ18 O showed higher broad-sense heritabilities ( H 2 ) than GY. Genotype means of GY across trials were negatively correlated with δ13 C, as previously reported, but not with δ18 O. Both isotopes were correlated with grain filling duration, whereas δ18 O was also strongly affected by crop duration from planting to anthesis. We concluded that δ18 O of grains is not a proper physiological trait to breed for suboptimal water conditions, as its variability is almost entirely determined by crop phenology. In contrast, δ13 C of grains, despite being also affected by phenology, still provides complementary information associated with GY. 相似文献
6.
Stable isotopes of nitrogen (δ15 N) and carbon (δ13 C) were measured for Atlantic salmon Salmo salar and their intestinal cestode, Eubothrium crassum , sharing the same diet. Atlantic salmon muscle tissues were enriched in 15 N and depleted in 13 C compared to their prey (sprat Sprattus sprattus sprattus ) and their intestinal cestode. There was no significant difference in δ15 N or δ13 C between E. crassum and the sprat. Differences in nutrient uptake and intestine physiology between Atlantic salmon and E. crassum are discussed, as well as how these may give rise to different fractionations of stable isotopes between a host and its parasites. Furthermore, Atlantic salmon contained a significantly higher lipid content than their prey, which may partly explain differences in δ13 C values between the host and its cestode. In addition, cestodes inhabiting lipid-rich hosts were also lipid rich. Larger Atlantic salmon were enriched in 15 N compared to smaller fish. Cestodes inhabiting large hosts were also enriched in 15 N compared to parasites living in smaller hosts. The last two results were explained by larger fish possibly feeding from a higher trophic level, or from larger and older prey, that resulted in both a higher lipid content and an enrichment in 15 N. 相似文献
7.
We investigated the extent to which plant water and nutrient status are affected by intraspecific competition intensity and microsite quality in a monodominant tussock grassland. Leaf gas exchange and stable isotope measurements were used to assess the water relations of Stipa tenacissima tussocks growing along a gradient of plant cover and soil depth in a semi-arid catchment of Southeast Spain. Stomatal conductance and photosynthetic rate decreased with increasing intensity of competition during the wet growing season, leading to foliar δ 18 O and δ 13 C enrichment. A high potential for runoff interception by upslope neighbours exerted strong detrimental effects on the water and phosphorus status of downslope S. tenacissima tussocks. Foliar δ 15 N values became more enriched with increasing soil depth. Multiple stepwise regression showed that competition potential and/or rhizosphere soil depth accounted for large proportions of variance in foliar δ 13 C, δ 18 O and δ 15 N among target tussocks (57, 37 and 64%, respectively). The results presented here highlight the key role that spatial redistribution of resources (water and nutrients) by runoff plays in semi-arid ecosystems. It is concluded that combined measurement of δ 13 C, δ 18 O and nutrient concentrations in bulk leaf tissue can provide insight into the intensity of competitive interactions occurring in natural plant communities. 相似文献
8.
1. We investigated the spatial (longitudinal position and reach geomorphology) and seasonal (spring and autumn) influences on the variation of δ13C among organic matter sources and consumers in a forested Piedmont river, South Carolina, U.S.A. 2. Six sites were sampled along a continuum and varied in basin area from approximately 30 to 300 km2. Sites fell into two geomorphic categories (i) high‐gradient, rock bed (‘rock’) or (ii) low‐gradient, sand bed (‘sand’) sites. 3. Variation in δ13C was more strongly related to reach geomorphology than longitudinal position. δ13C of biofilm and consumers was consistently enriched at rock sites. Leaf litter (i.e. coarse particulate organic matter, CPOM) δ13C did not vary with bed type. There was significant δ13C enrichment at rock sites for biofilm, seston, fine benthic organic matter (FBOM), and eight of nine consumer trophic guilds (e.g. grazing invertebrates, insectivorous fishes). δ13C of biofilm and four trophic guilds was also positively correlated with drainage area, but the magnitude of enrichment was less than between bed types. 4. δ13C was generally enriched in spring, but this varied among organic matter types, consumers, and by bed type. CPOM and seston were enriched in spring, FBOM was enriched in autumn, and biofilm showed no trend. Five consumer guilds were enriched in spring, and only one fish guild, generalised carnivores, showed enrichment of muscle tissue in autumn. 5. Consumer δ13C enrichment at rock sites suggests greater reliance on algal carbon than for consumers at sand sites, but we also found δ13C enrichment of biofilm at rock sites. Thus, differences in consumer δ13C between bed types could be related to (i) increased consumption of biofilm at rock compared with sand sites, or (ii) consumption of biofilm at rock sites that is enriched relative to biofilm at sand sites or (iii) both mechanisms. 6. δ13C signatures in local food webs appear to respond to processes operating at multiple spatial scales. Overall downstream enrichment of biofilm and consumers was disrupted by strong local effects related to bed morphology. These results suggest that human alteration of channel habitat will have corresponding effects on stream food webs, as assessed by changes in δ13C. 相似文献
9.
1. The variability in the stable isotope signatures of carbon and nitrogen (δ13C and δ15N) in different phytoplankton taxa was studied in one mesotrophic and three eutrophic lakes in south‐west Finland. The lakes were sampled on nine to 16 occasions over 2–4 years and most of the time were dominated by cyanobacteria and diatoms. A total of 151 taxon‐specific subsamples covering 18 different phytoplankton taxa could be isolated by filtration through a series of sieves and by flotation/sedimentation, followed by microscopical identification and screening for purity. 2. Substantial and systematic differences between phytoplankton taxa, seasons and lakes were observed for both δ13C and δ15N. The values of δ13C ranged from ?34.4‰ to ?5.9‰ and were lowest in chrysophytes (?34.4‰ to ?31.3‰) and diatoms (?30.6‰ to ?26.6‰). Cyanobacteria were most variable (?32.4‰ to ?5.9‰), including particularly high values in the nostocalean cyanobacterium Gloeotrichia echinulata (?14.4‰ to ?5.9‰). For δ13C, the taxon‐specific amplitude of temporal changes within a lake was usually <1–8‰ (<1–4‰ for microalgae alone and <1–8‰ for cyanobacteria alone), whereas the amplitude among taxa within a water sample was up to 31‰. 3. The values of δ15N ranged from ?2.1‰ to 12.8‰ and were high in chrysophytes, dinophytes and diatoms, but low in the nitrogen‐fixing cyanobacteria Anabaena spp., Aphanizomenon spp. and G. echinulata (?2.1‰ to 1.6‰). Chroococcalean cyanobacteria ranged from ?1.4‰ to 8.9‰. For δ15N, the taxon‐specific amplitude of temporal changes within a lake was 2–6‰, (2–6‰ for microalgae alone and 2–4‰ for cyanobacteria alone) and the amplitude among taxa within a water sample was up to 11‰. 4. The isotopic signatures of phytoplankton changed systematically with their physical and chemical environment, most notably with the concentrations of nutrients, but correlations were non‐systematic and site‐specific. 5. The substantial variability in the isotopic signatures of phytoplankton among taxa, seasons and lakes complicates the interpretation of isotopic signatures in lacustrine food webs. However, taxon‐specific values and seasonal patterns showed some consistency among years and may eventually be predictable. 相似文献
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LUCAS A. CERNUSAK KLAUS WINTER & BENJAMIN L. TURNER 《Plant, cell & environment》2009,32(10):1441-1455
Water-use efficiency and stable isotope composition were studied in three tropical tree species. Seedlings of Tectona grandis , Swietenia macrophylla and Platymiscium pinnatum were grown at either high or low water supply, and with or without added fertilizer. These three species previously exhibited low, intermediate and high whole-plant water-use efficiency ( TE ) when grown at high water supply in unfertilized soil. Responses of TE to water and nutrient availability varied among species. The TE was calculated as experiment-long dry matter production divided by cumulative water use. Species-specific offsets were observed in relationships between TE and whole-plant 13 C discrimination (Δ13 Cp ). These offsets could be attributed to a breakdown in the relationship between Δ13 Cp and the ratio of intercellular to ambient CO2 partial pressures ( c i / c a ) in P. pinnatum , and to variation among species in the leaf-to-air vapour pressure difference ( v ). Thus, a plot of v · TE against c i / c a showed a general relationship among species. Relationships between δ 18 O of stem dry matter and stomatal conductance ranged from strongly negative for S. macrophylla to no relationship for T. grandis . Results suggest inter-specific variation among tropical tree species in relationships between stable isotope ratios ( δ 13 C and δ 18 O) and the gas exchange processes thought to affect them. 相似文献
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M. DURANCEAU J. GHASHGHAIE F. BADECK E. DELEENS & G. CORNIC 《Plant, cell & environment》1999,22(5):515-523
The variations in δ 13 C in both leaf carbohydrates (starch and sucrose) and CO2 respired in the dark from the cotyledonary leaves of Phaseolus vulgaris L. were investigated during a progressive drought. As expected, sucrose and starch became heavier (enriched in 13 C) with decreasing stomatal conductance and decreasing p i / p a during the first half (15 d) of the dehydration cycle. Thereafter, when stomata remained closed and leaf net photosynthesis was near zero, the tendency was reversed: the carbohydrates became lighter (depleted in 13 C). This may be explained by increased p i / p a but other possible explanations are also discussed. Interestingly, the variations in δ 13 C of CO2 respired in the dark were correlated with those of sucrose for both well-watered and dehydrated plants. A linear relationship was obtained between δ 13 C of CO2 respired in the dark and sucrose, respired CO2 always being enriched in 13 C compared with sucrose by ≈ 6‰. The whole leaf organic matter was depleted in 13 C compared with leaf carbohydrates by at least 1‰. These results suggest that: (i) a discrimination by ≈ 6‰ occurs during dark respiration processes releasing 13 C-enriched CO2 ; and that (ii) this leads to 13 C depletion in the remaining leaf material. 相似文献
14.
Terrestrial arthropods are important components of boreal ecosystems but relatively little is known about their trophic structure within communities. We measured δ13 C and δ15 N values in a broad range of arthropod taxa (Coleoptera, Diptera, Ephemeroptera, Homoptera, Hymenoptera, Lepidoptera, Odonata, Orthoptera, Araneae) from boreal forest in Prince Albert National Park, Saskatchewan, Canada. Isotopic measurements supported previous conventional investigations on foraging niches based on stomach content analysis and direct feeding observations but additional, new information was also obtained using the stable isotope approach. Significant differences were observed in both δ15 N and δ13 C values between various orders and families or superfamilies within orders. Higher variance in stable isotope values for scavengers (e.g. carrion beetles; Coleoptera, Silphidae) and generalists (e.g. ground beetles; Coleoptera, Carabidae) was found compared to specialists (e.g. grasshoppers; Orthoptera). Consistent isotopic differences between terrestrial and aquatic species were not found. However, aquatic insect δ13 C values tended to be lower than those of their terrestrial counterparts. We discuss the potential for using stable isotope methods to reconstruct trophic linkages and interaction involving arthropods. 相似文献
15.
The antiquity of the use of seaweed to feed domestic animals was investigated through carbon ( δ 13 C) and oxygen ( δ 18 O) isotope analysis of tooth enamel bioapatite. The analysis was performed on sheep and cattle teeth from two Neolithic sites in Orkney (Scotland). At the Knap of Howar, c . 3600 bc , carbon isotopes reflect grazing on terrestrial plants throughout the year for both sheep and cattle, with no contribution of seaweed to their diet. At the Holm of Papa Westray North (HPWN), c . 3000 bc , significant contribution of seaweed to the sheep diet during winter is indicated by bioapatite δ 13 C values as high as −5.7‰, far outside of the range of values expected for the feeding on terrestrial C3 plants, and δ 18 O values higher than expected during winter, possibly caused by ingestion of oceanic water with seaweed. Ingestion of seaweed by sheep at HPWN might have been necessitated by severe reduction of pastures during winter. Results suggest that sheep ingested fresh seaweed rather than dry fodder, perhaps directly on the shore as sheep do nowadays on North Ronaldsay. A significant difference between the two populations is the exclusive reliance on seaweed by the North Ronaldsay sheep, which have developed physiological adaptations to this diet. Contribution of seaweed to the sheep winter diet at HPWN might have been a first step towards this adaptation. 相似文献
16.
J. Ghashghaie M. Duranceau F.-W. Badeck G. Cornic M.-T. Adeline & E. Deleens 《Plant, cell & environment》2001,24(5):505-515
The variations of δ13C in leaf metabolites (lipids, organic acids, starch and soluble sugars), leaf organic matter and CO2 respired in the dark from leaves of Nicotiana sylvestris and Helianthus annuus were investigated during a progressive drought. Under well‐watered conditions, CO2 respired in the dark was 13C‐enriched compared to sucrose by about 4‰ in N. sylvestris and by about 3‰ and 6‰ in two different sets of experiments in H. annuus plants. In a previous work on cotyledonary leaves of Phaseolus vulgaris, we observed a constant 13C‐enrichment by about 6‰ in respired CO2 compared to sucrose, suggesting a constant fractionation during dark respiration, whatever the leaf age and relative water content. In contrast, the 13C‐enrichment in respired CO2 increased in dehydrated N. sylvestris and decreased in dehydrated H. annuus in comparison with control plants. We conclude that (i) carbon isotope fractionation during dark respiration is a widespread phenomenon occurring in C3 plants, but that (ii) this fractionation is not constant and varies among species and (iii) it also varies with environmental conditions (water deficit in the present work) but differently among species. We also conclude that (iv) a discrimination during dark respiration processes occurred, releasing CO2 enriched in 13C compared to several major leaf reserves (carbohydrates, lipids and organic acids) and whole leaf organic matter. 相似文献
17.
Carlos Alberto Niño-Torres Juan Pablo Gallo-Reynoso † Felipe Galván-Magaña ‡ Elva Escobar-Briones § Stephen A. Macko 《Marine Mammal Science》2006,22(4):831-846
Stable isotopic analyses of carbon, nitrogen, and sulfur were performed on teeth of different ages and sexes of the longbeaked common dolphin, Delphinus capensis, from the Gulf of California. Similarities in diet are suggested between the sexes, with no significant differences in isotopic compositions being observed. Differences in the δ13 C, δ15 N, and δ34 S signatures were found among the age groups (nursing calf, juvenile, subadult, and adult). These data suggest that this species is generally a coastal feeder, and that it changes its feeding habits with increasing age, drawing more nutrition from higher trophic level organisms later in life. 相似文献
18.
Deborah Hemming Dan Yakir Per Ambus Mika Aurela Cathy Besson Kevin Black Nina Buchmann Regis Burlett Alessandro Cescatti Robert Clement Patrick Gross Andr Granier Thomas Grünwald Katarina Havrankova Dalibor Janous Ivan A. Janssens Alexander Knohl Barbara K
stner Andrew Kowalski Tuomas Laurila Catarina Mata Barbara Marcolla Giorgio Matteucci John Moncrieff Eddy J. Moors Bruce Osborne Joo Santos Pereira Mari Pihlatie Kim Pilegaard Francesca Ponti Zuzana Rosova Federica Rossi Andrea Scartazza Timo Vesala 《Global Change Biology》2005,11(7):1065-1093
We present carbon stable isotope, δ13C, results from air and organic matter samples collected during 98 individual field campaigns across a network of Carboeuroflux forest sites in 2001 (14 sites) and 2002 (16 sites). Using these data, we tested the hypothesis that δ13C values derived from large‐scale atmospheric measurements and models, which are routinely used to partition carbon fluxes between land and ocean, and potentially between respiration and photosynthesis on land, are consistent with directly measured ecosystem‐scale δ13C values. In this framework, we also tested the potential of δ13C in canopy air and plant organic matter to record regional‐scale ecophysiological patterns. Our network estimates for the mean δ13C of ecosystem respired CO2 and the related ‘discrimination’ of ecosystem respiration, δer and Δer, respectively, were ?25.6±1.9‰ and 17.8 ±2.0‰ in 2001 and ?26.6±1.5‰ and 19.0±1.6‰ in 2002. The results were in close agreement with δ13C values derived from regional‐scale atmospheric measurement programs for 2001, but less so in 2002, which had an unusual precipitation pattern. This suggests that regional‐scale atmospheric sampling programs generally capture ecosystem δ13C signals over Europe, but may be limited in capturing some of the interannual variations. In 2001, but less so in 2002, there were discernable longitudinal and seasonal trends in δer. From west to east, across the network, there was a general enrichment in 13C (~3‰ and ~1‰ for the 2 years, respectively) consistent with increasing Gorczynski continentality index for warmer and drier conditions. In 2001 only, seasonal 13C enrichment between July and September, followed by depletion in November (from about ?26.0‰ to ?24.5‰ to ?30.0‰), was also observed. In 2001, July and August δer values across the network were significantly related to average daytime vapor pressure deficit (VPD), relative humidity (RH), and, to a lesser degree, air temperature (Ta), but not significantly with monthly average precipitation (Pm). In contrast, in 2002 (a much wetter peak season), δer was significantly related with Ta, but not significantly with VPD and RH. The important role of plant physiological processes on δer in 2001 was emphasized by a relatively rapid turnover (between 1 and 6 days) of assimilated carbon inferred from time‐lag analyses of δer vs. meteorological parameters. However, this was not evident in 2002. These analyses also noted corresponding diurnal cycles of δer and meteorological parameters in 2001, indicating a rapid transmission of daytime meteorology, via physiological responses, to the δer signal during this season. Organic matter δ13C results showed progressive 13C enrichment from leaves, through stems and roots to soil organic matter, which may be explained by 13C fractionation during respiration. This enrichment was species dependent and was prominent in angiosperms but not in gymnosperms. δ13C values of organic matter of any of the plant components did not well represent short‐term δer values during the seasonal cycle, and could not be used to partition ecosystem respiration into autotrophic and heterotrophic components. 相似文献
19.
R. N. Sinnatamby J. E. Bowman J. B. Dempson † M. Power ‡ 《Journal of fish biology》2007,70(5):1630-1635
The scales of three species of fishes, yellow perch Perca flavescens , walleye Sander vitreus and Atlantic salmon Salmo salar , were acidified and the isotopic signatures were compared to non-acidified scales from the same fishes. No significant acidification effects on either carbon or nitrogen isotope signatures were found. Results contrast with earlier literature findings noting significant acidification effects and suggest acidification tests be undertaken before scales are used for temporal reconstruction of fish food web positions. 相似文献
20.
Fernando T. Maestre Susana Bautista Jordi Cortina 《植物学报(英文版)》2006,48(8):897-905
Recent studies have shown that the tussock grass Stipa tenacissima L. facilitates the establishment of late-successional shrubs, in what constitutes the first documented case of facilitation of woody plants by grasses. With the aim of increasing our knowledge of this interaction, in the present study we investigated the effects of S. tenacissima on the foliar δ13C, δ15N, nitrogen concentration, and carbon : nitrogen ratio of introduced seedlings of Pistacia lentiscus L., Quercus coccifera L., and Medicago arborea L. in a semi-arid Mediterranean steppe. Six months after planting, the values of δ13C ranged between -26.9‰ and -29.6‰, whereas those of δ15N ranged between -1.9‰ and 2.7‰. The foliar C : N ratio ranged between 10.7 and 53.5, and the nitrogen concentration ranged between 1.0% and 4.4%. We found no significant effect of the microsite provided by S. tenacissima on these variables in any of the species evaluated. The values of δ13C were negatively correlated with predawn water potentials in M. arborea and were positively correlated with relative growth rate in Q. coccifera. The values of δ15N were positively correlated with the biomass allocation to roots in the latter species. The present results suggest that the modification of environmental conditions in the are surrounding S. tenacissima was not strong enough to modify the foliar isotopic and nitrogen concentration of shrubs during the early stages after planting. 相似文献