共查询到20条相似文献,搜索用时 93 毫秒
1.
The influence of different feeding levels below and slightly above maintenance on whole body δ13 C and δ15 N values of Nile tilapia Oreochromis niloticus was examined. The energy budget of each fish was determined by indirect calorimetry. The δ13 C values of the lipid-free material of Nile tilapia fed below and slightly above maintenance level did not differ between the feeding groups, but the δ13 C values in the lipids and the δ15 N values of the lipid-free material showed small but significant differences. Those fish with a negative lipid retention had significantly higher δ13 C values in the lipid fraction compared to fish that synthesized fatty acids. There was a significant negative correlation between the amount of energy metabolized by the fish and both the δ13 C values in the lipids and the δ15 N values of the lipid-free material. Fasting and feeding below the maintenance level may influence the isotopic composition of animals and should therefore be considered in ecological and nutritional studies. 相似文献
2.
A. KOHZU T. YOSHIOKA T. ANDO M. TAKAHASHI K. KOBA & E. WADA 《The New phytologist》1999,144(2):323-330
The natural abundance of 13 C and 15 N was measured in basidiocarps of at least 115 species in 88 genera of ectomycorrhizal, wood-decomposing and litter-decomposing fungi from Japan and Malaysia. The natural abundance of 13 C and 15 N was also measured in leaves, litter, soil and wood from three different sites. 15 N and 13 C were enriched in ectomycorrhizal and wood-decomposing fungi, respectively, relative to their substrates. Ectomycorrhizal and wood-decomposing fungi could be distinguished on the basis of their δ13 C and δ15 N signatures. Although there was high variability in the isotopic composition of fungi, the following isotope- enrichment factors (ε, mean±SD) of the fungi relative to substrates were observed:
εectomycorrhizal fungi/litter = 6.1±0.4‰15 N
εectomycorrhizal fungi/wood = 1.4±0.8‰13 C
εwood-decomposing fungi/wood = −0.6±0.7‰15 N
εwood-decomposing fungi/wood = 3.5±0.9‰13 C
The basis of isotope fractionation in C metabolism from wood to wood-decomposing fungus is discussed. 相似文献
ε
ε
ε
ε
The basis of isotope fractionation in C metabolism from wood to wood-decomposing fungus is discussed. 相似文献
3.
We report a novel use of the 15 N dilution technique to detail the translocation of amino compounds in the legume Sesbania rostrata . The conventional 15 N dilution technique follows the dilution of 15 N within a labelled plant, as 14 N2 is fixed by symbiotic bacteria. In our experiments, stem-nodulated Sesbania rostrata were enriched by feeding with 15 N ammonium nitrate for 2 weeks, followed by a 1 week period where the only N available to the plants was via nitrogen fixation of atmospheric N2 . We measured the composition, concentration and 15 N enrichment of amino compounds in various plant tissues, both above and below the stem nodules, using GC-MS and isotopic abundance mass spectrometry techniques. Approximately 28% of the total N in the stem nodules was derived from internal plant sources. The ureides allantoic acid and allantoin were not abundant in xylem, leaf or nodule tissues. The amides asparagine and glutamine were the major export products from stem nodules although a wide range of other amino compounds are also synthesized. Amino acids within the nodules had a low level of enrichment, demonstrating that a small fraction (≈ 11%) was derived from outside the nodules, and significant cycling of N (28% of xylem N) through the root system was revealed by measurements of 15 N distribution and amino acid concentrations. 相似文献
4.
5.
This study investigated the impact of lipid extraction, CaCO3 removal and of both treatments combined on fish tissue δ13 C, δ15 N and C:N ratio. Furthermore, the suitability of empirical δ13 C lipid normalization and correction models was examined. δ15 N was affected by lipid extraction (increase of up to 1·65‰) and by the combination of both treatments, while acidification alone showed no effect. The observed shift in δ15 N represents a significant bias in trophic level estimates, i.e. lipid-extracted samples are not suitable for δ15 N analysis. C:N and δ13 C were significantly affected by lipid extraction, proportional to initial tissue lipid content. For both variables, rates of change with lipid content (ΔC:N and Δδ13 C) were species specific. All tested lipid normalization and correction models produced biased estimates of fish tissue δ13 C, probably due to a non-representative database and incorrect assumptions and generalizations the models were based on. Improved models need a priori more extensive and detailed studies of the relationships between lipid content, C:N and δ13 C, as well as of the underlying biochemical processes. 相似文献
6.
Effects of temperature and fertilization on nitrogen cycling and community composition of an urban lawn 总被引:3,自引:0,他引:3
NEETA S. BIJOOR CLAUDIA I. CZIMCZIK DIANE E. PATAKI † SHARON A. BILLINGS‡ 《Global Change Biology》2008,14(9):2119-2131
We examined the influence of temperature and management practices on the nitrogen (N) cycling of turfgrass, the largest irrigated crop in the United States. We measured nitrous oxide (N2 O) fluxes, and plant and soil N content and isotopic composition with a manipulative experiment of temperature and fertilizer application. Infrared lamps were used to increase surface temperature by 3.5±1.3 °C on average and control and heated plots were split into high and low fertilizer treatments. The N2 O fluxes increased following fertilizer application and were also directly related to soil moisture. There was a positive effect of warming on N2 O fluxes. Soils in the heated plots were enriched in nitrogen isotope ratio ( δ 15 N) relative to control plots, consistent with greater gaseous losses of N. For all treatments, C4 plant C/N ratio was negatively correlated with plant δ 15 N, suggesting that low leaf N was associated with the use of isotopically depleted N sources such as mineralized organic matter. A significant and unexpected result was a large, rapid increase in the proportion of C4 plants in the heated plots relative to control plots, as measured by the carbon isotope ratio ( δ 13 C) of total harvested aboveground biomass. The C4 plant biomass was dominated by crabgrass, a common weed in C3 fescue lawns. Our results suggest that an increase in temperature caused by climate change as well as the urban heat island effect may result in increases in N2 O emissions from fertilized urban lawns. In addition, warming may exacerbate weed invasions, which may require more intensive management, e.g. herbicide application, to manage species composition. 相似文献
7.
《The New phytologist》1998,139(3):595-595
The following citations were erroneously omitted from the 'References':
Groffman PM, Zak DR, Christensen S, Mosier A, Tiedje JM. 1993. Early spring nitrogen dynamics in a temperate forest landscape. Ecology 74 : 1579–1585.
Handley LL, Brendel O, Scrimgeour CM, Schmidt S, Raven JA, Turnbull MH, Stewart GR. 1996. The15 N natural abundance patterns of field-collected fungi from three kinds of ecosystems. Rapid Communications in Mass Spectrometry 10 : 974–978.
Handley LL, Daft MJ, Wilson J, Scrimgeour CM, Ingleby K, Sattar, MA. 1993. Effects of the ecto- and VA-mycorrhizal fungi Hydnagium carneum and Glomus clarum on the δ15 N and δ13 C values of Eucalyptus globulus and Ricinus communis. Plant, Cell and Environment 16 : 375–382.
Handley LL, Odee D, Scrimgeour CM. 1994. δ15 N and δ13 C patterns in savanna vegetation: dependence on water availability and disturbance. Functional Ecology 8 : 306–314.
Handley LL, Raven JH. 1992. The use of natural abundance of nitrogen isotopes in plant physiology and ecology: commissioned review. Plant, Cell and Environment 15 : 965–985.
Handley LL, Scrimgeour CM. 1997. Terrestrial plant ecology and15 N natural abundance: the present limits to interpretation for uncultivated systems with original data from a Scottish old field. Advances in Ecological Research 27 : 133–212.
Hansen AP, Pate JS. 1987. Evaluation of the15 N natural abundance method and xylem sap analysis for assessing N2 fixation of understorey legumes in jarrah ( Eucalyptus marginata Donn ex Sm.) forest in S.W. Australia. Journal of Experimental Botany 38 : 1446–1458.
New Phytologist apologizes unreservedly to all authors of the above papers for this error. 相似文献
Groffman PM, Zak DR, Christensen S, Mosier A, Tiedje JM. 1993. Early spring nitrogen dynamics in a temperate forest landscape. Ecology 74 : 1579–1585.
Handley LL, Brendel O, Scrimgeour CM, Schmidt S, Raven JA, Turnbull MH, Stewart GR. 1996. The
Handley LL, Daft MJ, Wilson J, Scrimgeour CM, Ingleby K, Sattar, MA. 1993. Effects of the ecto- and VA-mycorrhizal fungi Hydnagium carneum and Glomus clarum on the δ
Handley LL, Odee D, Scrimgeour CM. 1994. δ
Handley LL, Raven JH. 1992. The use of natural abundance of nitrogen isotopes in plant physiology and ecology: commissioned review. Plant, Cell and Environment 15 : 965–985.
Handley LL, Scrimgeour CM. 1997. Terrestrial plant ecology and
Hansen AP, Pate JS. 1987. Evaluation of the
New Phytologist apologizes unreservedly to all authors of the above papers for this error. 相似文献
8.
Transfer of nitrogen from a tropical legume tree to an associated fodder grass via root exudation and common mycelial networks 总被引:1,自引:0,他引:1
Symbiotic dinitrogen fixation by legume trees represents a substantial N input in agroforestry systems, which may benefit the associated crops. Applying 15 N labelling, we studied N transfer via common mycelial networks (CMN) and root exudation from the legume tree Gliricidia sepium to the associated fodder grass Dichantium aristatum . The plants were grown in greenhouse in shared pots in full interaction (treatment FI) or with their root systems separated with a fine mesh that allowed N transfer via CMN only (treatment MY). Tree root exudation was measured separately with hydroponics. Nitrogen transfer estimates were based on the isotopic signature of N ( δ 15 N) transferred from the donor. We obtained a range for estimates by calculating transfer with δ 15 N of tree roots and exudates. Nitrogen transfer was 3.7–14.0 and 0.7–2.5% of grass total N in treatments FI and MY, respectively. Root δ 15 N gave the lower and exudate δ 15 N the higher estimates. Transfer in FI probably occurred mainly via root exudation. Transfer in MY correlated negatively with grass root N concentration, implying that it was driven by source-sink relationships between the plants. The range of transfer estimates, depending on source δ 15 N applied, indicates the need of understanding the transfer mechanisms as a basis for reliable estimates. 相似文献
9.
J. PEARSON D. M. WELLS K. J. SELLER A. BENNETT A. SOARES J. WOODALL & M. J. INGROUILLE 《The New phytologist》2000,147(2):317-326
Mosses have been used as biomonitors of atmospheric pollution for some years, but few studies have been carried out on the effect of NOx emissions from traffic on moss tissue N. Eight species of moss (102 samples) growing on walls or roofs next to roads exposed to different traffic densities were collected from urban and rural sites in the UK. The shoots were sampled for total N, their stable isotope 15 N/14 N content (δ15 N) and heavy metal content (Pb, Zn). There was a lack of correlation between tissue total N and traffic exposure, but a very good correlation between traffic exposure and tissue δ15 N. Plants collected near motorways or busy urban roads had δ15 N values ranging between +6 and −1‰, while in rural areas with hardly any traffic these ranged from −2 to −12‰. In a separate survey of mosses, the average δ15 N of shoots from busy roadsides in London was +3.66‰, whereas from samples collected from farm buildings near poultry or cattle pens it was −7.8‰. This indicates that the two main atmospheric N sources, NOx and NHx , have different δ15 N signatures, the former tending to be positive and the latter negative. Tissue concentrations of both Pb and Zn show a strong positive correlation with traffic exposure, with Zn in particular being greater than Pb. The results are discussed with regard to the use of moss tissue Zn as a means for monitoring or mapping pollution from vehicles, and of δ15 N as an aid to distinguish between urban (NOx ) and rural (NHx ) forms of N pollution. 相似文献
10.
The scales of whitefish Coregonus lavaretus were used in place of dorsal muscle, which necessitates killing the fish, to study food webs from the δ13 C and δ15 N isotopic ratios in the organic fraction. As scales are composed of both organic and calcified fractions, a protocol for scale decalcification was first devised. The δ13 C and δ15 N values of the decalcified scales were then shown to be closely correlated to those of the dorsal muscle, demonstrating that scales could be used in place of muscle to study food webs. Changes in the δ13 C of whitefish were determined from a scale collection that extended over the period during which the trophic state of Lake Geneva was recovering. 相似文献
11.
Mycorrhizal and saprotrophic (SAP) fungi are essential to terrestrial element cycling due to their uptake of mineral nutrients and decomposition of detritus. Linking these ecological roles to specific fungi is necessary to improve our understanding of global nutrient cycling, fungal ecophysiology, and forest ecology. Using discriminant analyses of nitrogen (δ15 N) and carbon (δ13 C) isotope values from 813 fungi across 23 sites, we verified collector-based categorizations as either ectomycorrhizal (ECM) or SAP in > 91% of the fungi, and provided probabilistic assignments for an additional 27 fungi of unknown ecological role. As sites ranged from boreal tundra to tropical rainforest, we were able to show that fungal δ13 C (26 sites) and δ15 N (32 sites) values could be predicted by climate or latitude as previously shown in plant and soil analyses. Fungal δ13 C values are likely reflecting differences in C-source between ECM and SAP fungi, whereas 15 N enrichment of ECM fungi relative to SAP fungi suggests that ECM fungi are consistently delivering 15 N depleted N to host trees across a range of ecosystem types. 相似文献
12.
Symbiotic N2 fixation in a high Alpine grassland: effects of four growing seasons of elevated CO2 总被引:1,自引:0,他引:1
J. A. Arnone Iii 《Functional ecology》1999,13(3):383-387
1. Increasing carbon dioxide concentration (E: 680 μl CO2 litre–1 vs ambient, A: 355 μl CO2 litre–1 ) around late-successional Alpine sedge communities of the Swiss Central Alps (2450 m) for four growing seasons (1992–1995) had no detectable effect on symbiotic N2 fixation in Trifolium alpinum —the sole N2 -fixing plant species in these communities (74 ± 30 mg N m–2 year–1 , A and E plots pooled).
2. This result is based on data collected in the fourth growing season showing that elevated CO2 had no effect on Trifolium above-ground biomass (4·4 ± 1·7 g m–2 , A and E plots pooled, n = 24) or N content per unit land area (124 ± 51 mg N m–2 , A and E pooled), or on the percentage of N Trifolium derived from the atmosphere through symbiotic N2 fixation (%Ndfa: 61·0 ± 4·1 across A and E plots) estimated using the 15 N dilution method.
3. Thus, it appears that N inputs to this ecosystem via symbiotic N2 fixation will not be dramatically affected in the foreseeable future even as atmospheric CO2 continues to rise. 相似文献
2. This result is based on data collected in the fourth growing season showing that elevated CO
3. Thus, it appears that N inputs to this ecosystem via symbiotic N
13.
1. The δ13 C and δ15 N signatures of zooplankton vary with dissolved organic carbon (DOC), but inconsistent and limited taxonomic resolution of previous studies have masked differences that may exist among orders, genera or species and are attributable to dietary and/or habitat differences. Here we investigate differences among the isotopic signatures of five zooplankton taxa ( Daphnia , Holopedium , large Calanoida, small Calanoida and Cyclopoida) in Precambrian shield lakes with a sixfold range of DOC concentration.
2. δ13 C signatures of Daphnia , small calanoids and large calanoids became more depleted with increasing lake DOC, whereas Holopedium and cyclopoid δ13 C became enriched with increasing DOC concentration.
3. The variability of δ13 C and δ15 N isotopic signatures among zooplankton groups was reduced in high-DOC, compared to low-DOC lakes, especially for δ13 C. Differences in δ13 C and POM-corrected δ15 N accounted for up to 33.7% and 19.5% of the variance, respectively, among lakes of varying DOC concentration.
4. The narrow range of signatures found in higher DOC lakes suggests that different taxa have similar food sources and/or habitats. In contrast, the wide range of signatures in low-DOC lakes suggests that different taxa are exploiting different food sources and/or habitats. Together with the variable trends in zooplankton isotopic signatures along our DOC gradient, these results suggest that food web dynamics within the zooplankton community of temperate lakes will change as climate and lake DOC concentrations change. 相似文献
2. δ
3. The variability of δ
4. The narrow range of signatures found in higher DOC lakes suggests that different taxa have similar food sources and/or habitats. In contrast, the wide range of signatures in low-DOC lakes suggests that different taxa are exploiting different food sources and/or habitats. Together with the variable trends in zooplankton isotopic signatures along our DOC gradient, these results suggest that food web dynamics within the zooplankton community of temperate lakes will change as climate and lake DOC concentrations change. 相似文献
14.
Red clover, Trifolium pratense L., is the dominant forage legume in Sweden and is usually harvested twice per year, once in June and once in August. Two 15 N-based methods –15 N isotopic dilution (ID) and 15 N natural abundance (NA) – were used to study N2 fixation from spring until first harvest in late June, from first to second harvest in late August, and from second harvest until first frost in autumn in Umeå, Sweden. The material studied comprized three neighbouring fields carrying a first year ley, a second year ley and a third year ley. For the 15 N ID method, small amounts of highly enriched 15 N-nitrate were added to experimental plots. The non-legumes in the plots, essentially Phleum pratense L. together with Festuca pratensis L., served as reference plants for both the ID and 15 N NA measurements. Dry matter, N and 15 N were separately analysed in leaves (laminae), stems (including petioles), stubble and roots. The proportion of N derived from air (pNdfa) was then calculated for each plant part and for whole plants. Estimates of the proportion of N derived from N2 fixation (pNdfa) were always very high, usually ≥0.8. Generally, estimates of pNdfa obtained by the ID and NA methods were similar, but the ID method gave higher estimates of pNdfa than the NA method when the highest N2 fixation levels were recorded, at the August harvest. Regression analyses suggest that estimates of pNdfa in leaves could provide useful indications of pNdfa in shoots and whole T. pratense plants, thus avoiding the need for time-consuming root analyses. 相似文献
15.
R. L. FRANCE 《Freshwater Biology》1996,36(1):1-6
1. Although marine research has indicated that metabolic fractionations of 13 C due to differences in organismal trophic position and proximal composition can complicate the isotopic interpretation of energy flow pathways, such potentially confounding problems have never been examined in freshwater benthic food webs.
2. The δ13 C values of animals comprising a littoral benthic food web composited from four Canadian Shield lakes showed no relationship with either individual trophic position (δ15 N) or lipid content (C/N ratios).
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ13 C and δ15 N values, thereby masking any possibility of observing 13 C trophic enrichment.
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ13 C for freshwater benthic organisms in order to accommodate trophic fractionations which are presumed to occur, based on data from marine offshore food webs, may also be inappropriate. 相似文献
2. The δ
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ
16.
1. Although marine research has indicated that metabolic fractionations of 13 C due to differences in organismal trophic position and proximal composition can complicate the isotopic interpretation of energy flow pathways, such potentially confounding problems have never been examined in freshwater benthic food webs.
2. The δ13 C values of animals comprising a littoral benthic food web composited from four Canadian Shield lakes showed no relationship with either individual trophic position (δ15 N) or lipid content (C/N ratios).
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ13 C and δ15 N values, thereby masking any possibility of observing 13 C trophic enrichment.
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ13 C for freshwater benthic organisms in order to accommodate trophic fractionations which are presumed to occur, based on data from marine offshore food webs, may also be inappropriate. 相似文献
2. The δ
3. Differences in the relative incorporation of autochthonous and allochthonous energy sources by freshwater benthic organisms will alter their δ
4. Removal of the possibly confounding influences of lipids through either empirical correction or by analytical extraction may be unnecessary in studies of freshwater benthic food webs. Likewise, a priori adjustments in δ
17.
Interactive effects of elevated atmospheric CO2 and arbuscular mycorrhizal (AM) fungi on biomass production and N2 fixation were investigated using black locust ( Robinia pseudoacacia ). Seedlings were grown in growth chambers maintained at either 350 μmol mol−1 or 710 μmol mol−1 CO2 . Seedlings were inoculated with Rhizobium spp. and were grown with or without AM fungi. The 15 N isotope dilution method was used to determine N source partitioning between N2 fixation and inorganic fertilizer uptake. Elevated atmospheric CO2 significantly increased the percentage of fine roots that were colonized by AM fungi. Mycorrhizal seedlings grown under elevated CO2 had the greatest overall plant biomass production, nodulation, N and P content, and root N absorption. Additionally, elevated CO2 levels enhanced nodule and root mass production, as well as N2 fixation rates, of non- mycorrhizal seedlings. However, the relative response of biomass production to CO2 enrichment was greater in non-mycorrhizal seedlings than in mycorrhizal seedlings. This study provides strong evidence that arbuscular mycorrhizal fungi play an important role in the extent to which plant nutrition of symbiotic N2 -fixing tree species is affected by enriched atmospheric CO2 . 相似文献
18.
Trophic position, and often the source of feeding of predators in food webs, can be estimated using measurements of stable isotope ratios of nitrogen and carbon in predators and their prey. Muscle samples from 60 harp seals ( Pagophilus groenlandicus ) collected during May 1995 in nearshore waters of New foundland, Canada, were analyzed for δ13 C and δ15 N values. These values were compared with those for 63 prey samples representing seven species generally collected near the same area. Using diet-tissue isotopic fractionation factors derived from previous studies using captive animals, we infer a greater dependence of harp seals on lower trophic-level prey during April compared with results expected from exclusive diets of Atlantic cod ( Gadus morhua ), Atlantic herring ( Clupea harengus ), Greenland halibut ( Reinhardtius hippoglossoides ), or northern shrimp ( Pandalus borealis ). Our mean δ15 N value for harp seals is lower than previous findings for seals collected on the winter whelping patch and may be a function of interannual or seasonal differences in diet. Subadult seals (aged 1-4 yr) had significantly lower δ15 N values than adults (5 + yr), suggesting that older seals were feeding at a slightly higher trophic level. 相似文献
19.
R. L. France 《Freshwater Biology》1999,41(1):101-105
1. Littoral biota in boreal lakes are known to assimilate epilithon. Being able to predict the stable isotopic composition of these alga will help to identify those systems in which δ13 C and δ15 N analysis can be used in foodweb investigations of allochthony and biomagnification.
2. In a survey of 15 boreal lakes, the concentration of dissolved organic carbon (DOC) explained 76% of the variation in epilithon δ13 C, and 86% of the variation in epilithon δ15 N.
3. Because both δ13 C and δ15 N values were depressed and similar to terrestrial values in humic (high DOC) lakes, it will be more difficult to successfully employ stable isotopic techniques for estimating allochthony in such systems. Lower δ15 N values in humic lakes also indicate that trophic positions estimated by stable isotopes are not directly comparable to those of similar biota inhabiting clearwater lakes, unless autochthonous baseline corrections are made. 相似文献
2. In a survey of 15 boreal lakes, the concentration of dissolved organic carbon (DOC) explained 76% of the variation in epilithon δ
3. Because both δ
20.
Feather stable-isotope profiles reveal stopover habitat selection and site fidelity in nine migratory species moving through sub-Saharan Africa 总被引:4,自引:0,他引:4
Stable nitrogen (δ15 N), carbon (δ13 C) and hydrogen (δD) isotope profiles in feathers of nine migratory bird species trapped in Kenya were examined to test the extent to which they were segregated, geographically or by habitat, during an earlier autumn migration stopover in northeast Africa. We examined whether isotopic differences between species varied between years, and whether the isotope profiles of individual species appeared to be consistent. The relationship between mean feather δ13 C, δ15 N and δD assorted the migrants into several clustered groups. Similar feather isotope values among successive years revealed that each species tended to return to the same or similar stopover areas and selected habitat and diet that generated similar isotopic signatures. Possible explanations are discussed for the existence of these isotopic groups. 相似文献