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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 52 (2001), S. 0 
    ISSN: 1365-2389
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Soil solution was collected to identify seasonal trends in its chemistry and to examine relationships between the concentrations of ions and variables that may control them. Samples were collected fortnightly at 10 cm and 50 cm depth in a blanket peat soil at Moor House–Upper Teesdale National Nature Reserve in the northern Pennine uplands of England. Dissolved organic carbon at 10 cm peaked each summer and correlated most strongly with temperature. At both depths Na+ and Cl– were the dominant ions, reflecting the oceanic climate. Over the 3-year sampling period, concentrations of the principal anions and cations at 10 cm varied little except during the autumns of 1994 and 1995 following unusually dry summers. At these times concentrations of SO42–-S increased from 〈 3 μmol to a maximum of 430 μmol and were balanced by smaller increases in Na+, Mg2+, Ca2+ and H+. The SO42– concentration at 10 cm was most strongly correlated with depth to the water 〈link href="#t3"〉Table 3 weeks prior to sampling. At 50 cm depth in the peat a small increase in SO42– occurred only during the autumn of 1995, and the concentration of SO42– at this depth correlated most strongly with that at 10 cm. At neither depth were there any strong correlations with deposition. The increase in H+ concentration associated with the peak in SO42– at 10 cm depth represents a fall in pH from usual values around 4.2 to 3.5.〈tabular xml:id="t3"〉3〈title type="main"〉 Deposition flux of ions in bulk precipitation at Moor House from weekly samplings 1994 to 1996 in kg ha−1 year−1. The UK flux is derived from 32 sites of the United Kingdom Precipitation Composition Monitoring Network 1992 to 1994 and the standard deviation (SD) relates to the variation between these sites (Review Group on Acid Rain, 1997) 〈table frame="topbot"〉〈tgroup cols="4" align="left"〉〈colspec colnum="1" colname="col1"/〉〈colspec colnum="2" colname="col2" align="char" char="."/〉〈colspec colnum="3" colname="col3" align="char" char="."/〉〈colspec colnum="4" colname="col4" align="char" char="."/〉〈thead valign="bottom"〉〈row rowsep="1"〉Moor House fluxUK fluxUK SD〈tbody valign="top"〉H+0.310.260.10Ca2+4.073.581.86Mg2+3.373.622.62K+1.54Fe2+0.73Al3+0.44Na+29.3225.7719.27Cl–51.1445.9632.39NO3–-N4.013.201.05NH4+-N4.853.631.74SO42–-S8.987.983.09PO43–-P0.01
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1939
    Schlagwort(e): Key words Deciduous ; Evergreen ; Nitrogen ; Potassium ; Specific leaf area
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract This study aimed to identify functional correlates of seedling leaf nutrient content among woody species and to characterise functional species groups with respect to leaf nutrient attributes. Seedlings of 81 woody species from the temperate zone of western Europe were grown in a standard laboratory environment with standard, near-optimal nutrient availability. Weight-based leaf N content (Nwght) was positively correlated with mean relative growth rate (RGR), but the correlation with mean RGR was tighter when leaf N was expressed on a whole-plant weight basis: leaf nitrogen weight ratio (LNWR). Area-based leaf N content (Narea) was not associated with mean RGR, but was closely correlated with the quotient of saturated leaf weight and leaf area. Weight-based leaf K content (Kwght) was a close correlate of the saturated/dry weight ratio of the foliage. Within the lower range, Kwght corresponded with growth-related nutrient attributes, but higher values appeared to indicate succulence or remobilisable stored water. Functional groups of species and genera could be distinguished with respect to seedling leaf nutrient attributes. Deciduous woody climbers and scramblers had consistently higher leaf Nwght, LNWR and (apparently) leaf Kwght than other deciduous species or genera, and shrubs had higher values than trees. These differences seemed due partly to variation in specific leaf area. Evergreens had consistently higher leaf Narea than deciduous plants, but there were no significant differences in weight-based leaf nutrient attributes between these two groups, possibly because of `luxury nutrient consumption' by the slow-growing evergreens. Another functional group was that of the nitrogen-fixing species, which had consistently high innate leaf Nwght compared to non-N-fixers. The ecological significance of the leaf nutrient attributes in this study is discussed by comparing the seedling data with those from field-collected material, and by brief reference to the natural habitats of the species.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 163 (1994), S. 121-130 
    ISSN: 1573-5036
    Schlagwort(e): decomposition rates ; enriched CO2 ; lignin ; litter respiration ; microcosms ; nitrogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Ash (Fraxinus excelsior L.), birch (Betula pubescens Ehrh.), sycamore (Acer pseudoplatanus L.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) leaf litters were monitored for decomposition rates and nutrient release in a laboratory microcosm experiment. Litters were derived from solar domes where plants had been exposed to two different CO2 regimes: ambient (350 μL L-1 CO2) and enriched (600 μL L-1 CO2). Elevated CO2 significantly affected some of the major litter quality parameters, with lower N, higher lignin concentrations and higher ratios of C/N and lignin/N for litters derived from enriched CO2. Respiration rates of the deciduous species were significantly decreased for litters grown under elevated CO2, and reductions in mass loss at the end of the experiment were generally observed in litters derived from the 600 ppm CO2 treatment. Nutrient mineralization, dissolved organic carbon, and pH in microcosm leachates did not differ significantly between the two CO2 treatments for any of the species studied. Litter quality parameters were examined for correlations with cumulative respiration and decomposition rates: N concentration, C/N and lignin/N ratios showed the highest correlations, with differences between litter types. The results indicate that higher C storage will occur in soil as a consequence of litter quality changes resulting from higher atmospheric concentrations of CO2.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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