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  • 1
    Digitale Medien
    Digitale Medien
    Experimental manipulations of water and nutrient input to a Norway spruce plantation at Klosterhede, Denmark (1995)
    Springer
    Plant and soil 168-169 (1995), S. 601-611 
    Details
    ISSN: 1573-5036
    Schlagwort(e): drought ; nutrient cycling ; potassium ; soil solution ; spatial variability ; throughfall
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract At Klosterhede, Denmark experimental manipulations of water and nutrient inputs to a forest stand were carried out under a 1200 m2 roof simulating i) summer drought, ii) removal of N and S input, and iii) optimal nutrition and water availability. In practise, manipulation of element fluxes in a complex system like a forest may cause unintended changes such as climatic effects from the roof which may interfere with the results of the intended manipulation. This paper illustrates the extent and effects of such unintended changes. The most important climatic change under the roof was a 50% reduction of photosynthetic light which caused a decrease in moss cover on the ground floor. Soil temperatures under the roof were decreased 0.3°C during summer and increased 0.2°C during winter. Air humidity was not changed. Throughfall water amount decreased close to the stems whereas element concentrations in throughfall increased close to the stems and with tree size on the ambient plots. This distinct spatial pattern was changed under the roof to a more variable water distribution from the sprinkling system and to constant element concentrations in the sprinkling water. This loss/change of spatial variability in the input was reflected in the soil solution. The concentration patterns found in soil water (increasing close to the stem and with tree size) in the ambient plots were no longer observed under the roof. Exclusion of throughfall by the roof disturbed the internal cycle of nutrients leached from the canopy. The removal of canopy leached Ca and K by the roof caused a decline in soil water concentrations, even on the drought plot where natural throughfall was only cut off during two summer months. The internal cycle of Ca and K had to be restored by addition of Ca and K under the roof. Further, leachable elements and soluble compounds may be washed out from litterfall during the collection period on the roof, and thus lost from the internal cycle by by exclusion of throughfall. It is important to consider these problems in the design of new manipulation experiments and in the interpretation of the results. Some recommendations are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029374
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  • 2
    Digitale Medien
    Digitale Medien
    Experimental manipulations of water and nutrient input to a Norway spruce plantation at Klosterhede, Denmark (1995)
    Springer
    Plant and soil 168-169 (1995), S. 623-632 
    Details
    ISSN: 1573-5036
    Schlagwort(e): atmospheric deposition ; biogeochemical cycling ; decomposition ; experimental manipulations ; soil water chemistry ; throughfall
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract At Klosterhede, Denmark experimental manipulations of the input of water and nutrients to a Norway spruce forest stand have been performed. The manipulations included fertilizer application, irrigation and creation of artificial dry periods. Further, the acidic input was excluded from the soil by a 1200 m2 roof. The aim of this study was to quantify the effects of air pollutants on the internal cycling of nutrients in the forest ecosystem and to assess the influence of the manipulations on the canopy interacting processes, the soil water composition and the turnover of organic matter. The improved nutrient availability and the increased soil water content in the fertigation (fertilizer application + irrigation) and the irrigation plots under the roof resulted in an increased decomposition of cotton strips compared to the uncovered control plot. However, the decomposition of needle material (litterbags) in the roof covered plots was reduced probably due to altered humidity conditions in the humic layer as a result of the irrigation system. Significant changes to the manipulations were seen in the soil water concentrations of SO4 2- in the irrigated and the fertigated plots and of K+ in the irrigated plot which show that the internal cycling and dynamics of sulphur and potassium are very sensitive to interference in the input. The effect of reduced acid input on soil water concentrations of Al and H+ was not evident before the 5th year of treatment where Al concentration was reduced almost 50% at 55 cm depth on the “clean rain” (irrigated) plot. It was not possible to detect any enlarged throughfall deposition on the fertigated and irrigated plots despite an observed rise in the canopy surface area on these plots or to detect any changes in canopy leaching reflecting changes in nutrient status.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029376
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  • 3
    Digitale Medien
    Digitale Medien
    Female-to-male sex pheromones of low volatility in the Asian elephant,Elephas maximus (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 2115-2128 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Elephas maximus ; Asian elephant ; preovulatory pheromone ; tryptanthrine indolo[2,1-b]-quinazoline-6,12-dione ; novel substance response ; estrus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract In their natural ecosystems, the sexes of Asian elephants,Elephas maximus, live separately. For several weeks prior to ovulation, the urine and cervical mucus of female Asian elephants contain extractable chemical agents of low volatility that elicit a high frequency of flehmen responses from bull elephants as an integral part of mating. Subsequent to flehmen responses, male sexual arousal occurs and, if the female is available, mating results. During the course of our project to determine the agent(s) and describe the responses associated with female to male sexual communication, we have identified an unusual compound. This compound, apparently the sole component of the active fraction, was identified by mass, proton nuclear magnetic resonance, ultraviolet/visible, and infrared spectrometries as indolo-[2,1-b] quinazoline-6,12-dione (tryptanthrine). Exhaustive and repetitive bioassays established that pure authentic (synthetic) tryptanthrine was not the compound responsible for the bioresponse. Rather a coeluting minor component, also of low volatility, elicited the male bioresponse.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00979651
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  • 4
    Digitale Medien
    Digitale Medien
    A method for collection, long-term storage, and bioassay of labile volatile chemosignals (1996)
    Springer
    Journal of chemical ecology 22 (1996), S. 207-221 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Chemosignal ; pheromone ; Asian elephant ; Elephas maximus ; temporal gland secretion ; musth ; avoiding reactions ; headspace analysis ; 2-hexanone ; 3-pentanone ; 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract A procedure for headspace sampling and long-term storage of organic volatiles coupled with gas chromatographic-mass spectrometric (GC-MS) analysis was used to study the volatile chemosignals in a biological secretion prior to bioassay. The approach involved collecting the volatiles in evacuated canisters from an apparatus in which 1 ml of secretion was dispersed for headspace sampling. These canisters, stainless steel, 850 ml, and 100% internally electropolished, have been demonstrated to store volatile compounds, in chemically stable form, for several weeks. The GC-MS analyses provided the quantitation and identification of compounds from C3 through C14 at concentrations as low as 0.10 parts per billion volume. The approach was used to study chemosignals of musth temporal gland secretions (TGS) from a male Asian elephant (Elephas maximus). Fresh TGS material loses its biological activity within 1 hr. TGS material stored at −20°C usually looses its activity within 30 days. The usefulness of this method for long-term storage of the volatile chemosignals was demonstrated by the retention of biologically active TGS headspace compounds, as determined through bioassays, stored in these canisters for one year.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02055093
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