Zur Nahrungswahl und Nagetätigkeit der Erdmaus Microtus agrestis L

Zusammenfassung Zur Erweiterung der Kenntnisse über die Ernährung der Erdmaus,Microtus agrestis L., wurden verschiedene Gräser und Kräuter zur Nahrungswahl sowie Fichten und-äste, letztere mit und ohne Zusatznahrung, zum Benagen geboten.Unter 20 vorgelegten Pflanzenarten entfiel aufTrifolium pratense die höchste Präferenz, gefolgt vonCalamagrostis epigeios, Urtica dioica undEpilobium angustifolium. Der Präferenzgrad war weder mit dem Wassergehalt noch mit dem Gehalt an Nährstoffen und Spurenelementen korreliert. Die Nageintensität an Fichtenaststücken hing nicht vom Wassergehalt der Äste ab, wohl aber vom Umfang des Grünfutters. Nur bei Mangel an Grünfutter kam es zu starken Nageschäden.Überraschend wurden im Terrarium mit relativ lockerem Boden fast nur die Wurzeln und nicht, wie im Freiland üblich, die Rinde am Stammgrund gefressen. Die Erdmaus scheint bei weichem Boden die Wurzeln, bei festem Boden die Stammrinde der Fichte zu bevorzugen. Falls die Rinde Verletzungen zeigte, lockte dies die Erdmaus an und stimulierte sie zum Rindenfraß.

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Studies on food choice and gnawing activity of the field vole, Microtus agrestis L

Studies made on encaged voles showedTrifolium pratense having the highest degree of food preference among 20 gramineous and herbaceous plant species followed byCalamagrostis epigeios, Urtica dioica andEpilobium angustifolium. The attractivity of plants depended neither on water content nor on nutritive substances. The intensiveness of gnawing the bark of spruce branches did'nt depend on water content, but depended on the quantity of herbaceous diet beeing available at the same time. Giving whole young spruces planted in cages the voles fed surprisingly almost only on the roots and not on the bark of stem basis as usual in the field.M. agrestis seems to be a root pest in weak soils (as given in the cages) and a bark pest on normal hard soils. This corresponds with some observations in the field (Bäumler verb.). Little damages of bark attracted the voles and stimulated their gnawing activity.

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Mit 5 Tabellen     

The water vapor sorption mechanism and its hysteresis in wood: the water/void mixture postulate

A new method of wood moisture sorption analysis is presented using sorption isotherms of a series of mildly heat-treated specimens with varied and known elemental composition. This method allows the determination of the occupancy of accessible sorption sites in wood as a function of relative humidity h, θ(h) ≈ h, found in agreement with the literature data on the non-freezing water occupancy of hydroxyl groups for h < 0.9. Complementary sorption isotherm shape analysis identifies an empirical power law occupancy function, θ(h) = h ^α , α ≈ 0.73, which is close to the former two determinations in the same humidity range. The validity of widely accepted surface sorption theories for wood with a strongly bound primary layer and loosely bound secondary layers is disproven. To explain the found occupancy function, θ(h) ≈ h, a near-ideal liquid mixture of moisture and polar dynamic microvoids in the cell wall substance is postulated. The power law occupancy function is used to calculate the humidity-dependent number of sorption sites in adsorption/desorption isotherms to show that (1) the number of sorption sites from the adsorption line monotonically increases with increasing humidity—argued to represent the equilibrium number of sorption sites at each humidity, and (2) the number of sorption sites from the desorption line fails to fully return to that of the (equilibrium) adsorption line. Hysteresis is quantitatively explained as the result of non-equilibrium excess sorption sites being occupied according to the occupancy law. The relaxation of non-equilibrium excess sorption sites is satisfactorily modeled by a first-order rate equation. Applying the analysis to study mild thermal modification of moisture sorption isotherms revealed that (1) moisture contents decrease directly linear to the removed amount of sorption sites at all humidity <0.95, and (2) the absolute hysteresis is nearly unaffected as a result of counter-acting effects of the reduced number of sorption sites and reduced amount of relaxation.     

Vergleichende Untersuchungen der Mineralstoffgehalte geschädigter und nicht geschädigter Rotbuchen (Fagus sylvatica) auf Muschelkalkstandorten im Saarland

Comperative study of the mineral content of damaged and visibly healthy red beeches (Fagus sylvatica) on limestone soils in the Saarland 50-80 years old red beeches from a limestone region in the Saarland, differentiated in apparently healthy and diseased trees, were investigated on their mineral content beginning with the roots over stem up to the leaves. Macro- and microelement contents were different between healthy and diseased trees. Magnesium content in the roots of the latter was markedly reduced. Also zinc and phosphorous were decreased in the damaged trees, while manganese was partially accumulated. On the other side, a high sulphur content was observed in the crown area of both types of trees.     

Resistenzeigenschaften im Gersten- und Weizensortiment Gatersleben 20. Prüfung des Verhaltens von Gersten gegen Flugbrand,Ustilago nuda (Jens.) Rostr.

Zusammenfassung In den Jahren 1964 bis 1974 wurden 362 Winter- und 738 Sommergersten mit einer lokalen Population vonUstilago nuda geprüft. Zur Kennzeichnung der Virulenz des Infektionsmaterials ist das Verhalten von Trägern bekannter Resistenzgene angegeben. Resistenz (0 ... 10% Befall) zeigten 197 oder 18% der 1100 Gersten. Mäßig resistent bis mäßig anfällig (>10 ... 30% Befall) waren 146 oder 13% dieses Sortiments. Als anfällig wurden 69% der Kollektion bewertet.Im Zusammenhang mit diesen Ergebnissen wird auf die Literatur zur Genetik der Flugbrandresistenz und auf Kombinationen mit anderen Resistenzmerkmalen eingegangen.

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Resistance in the Gatersleben barley and wheat collection. 20. Testing of barley for reaction to loose smut,Ustilago nuda (Jens.) Rostr.

Summary During the years 1964–74 362 winter and 738 spring barleys were inoculated with a local smut population. Its virulence is described by the reactions of varieties with identified resistance genes.Of the 1100 varieties tested 197 were resistant (0 ... 10% infection), 146 showed >10 ... 30% infection, and 69 per cent of this collection were classified as susceptible, with infection exceeding 30%.In connection with these results literature on smut resistance and the combination with resistance to other diseases are discussed.

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. 20. , Ustilago nuda (Jens.) Rostr.

1964 1974 . 362 738 Ustilago nuda. . ( 0 10%) 197 1100 (18%). ( 10 30%) 146 (13%). 69% . .

     

Energetics of load carrying in Nepalese porters

Nepalese porters routinely carry head-supported loads equal to 100 to 200% of their body weight (Mb) for many days up and down steep mountain footpaths at high altitudes. Previous studies have shown that African women carry head-supported loads of up to 60% of their Mb far more economically than army recruits carrying equivalent loads in backpacks. Here we show that Nepalese porters carry heavier loads even more economically than African women. Female Nepalese porters, for example, carry on average loads that are 10% of their Mb heavier than the maximum loads carried by the African women, yet do so at a 25% smaller metabolic cost.     

Does nectar reward affect rarity and extinction probabilities of orchid species? An assessment using historical records from Belgium and the Netherlands

The long-term persistence of plant populations may partly depend on pollination processes and seed production. The exact role of pollination in determining plant population viability still remains largely unclear. Orchid species have often been shown to be pollinator limited. Especially, non-rewarding species are characterized by infrequent pollinator visits and low seed set. Therefore, it can be hypothesized that, if overall population fitness of orchid species is influenced by seed production, non-rewarding species should be more prone to local extinction than rewarding species. To study the importance of nectar reward on orchid persistence, we collected historical records about the distribution of 32 orchid species in Flanders (Belgium) and 37 orchid species in the Netherlands. For both regions, present distribution patterns were compared with historical data. Between 1930 (Flanders) or 1950 (the Netherlands) and 2000, 26 (81%) species showed decreases in distribution range in Flanders, eight of which had gone extinct, whereas 29 (78%) species showed declines in distribution area in the Netherlands, five of which went extinct. Contrary to previously reported results, orchid distribution patterns were not related to nectar reward. There was also no significant relationship between nectar reward and extinction for both regions. Orchids typically occurring in wet grasslands and heathlands suffered greater losses than orchids typically confined to forest habitats or calcareous grasslands. We conclude that the production of nectar does not represent a safeguard for local extinction of orchid species. Habitat loss and other deterministic threats associated with habitat fragmentation and deterioration are more important determinants of orchid persistence.     

Comparative genetic characterization of Porcine Circovirus type 2 samples from German wild boar populations

PCV-2 is involved in "postweaning multisystemic wasting syndrome" (PMWS), "porcine dermatitis and nephropathy syndrome" (PDNS), respiratory and reproductive disorders, and thereby plays a crucial role in today's swine production world-wide. The virus is apparently ubiquitous in domestic pigs and has also been demonstrated in wild pigs. Up to now, a characterization of PCV-2 samples from wild pigs, which might help to estimate the possible role of wild pigs as sources of domestic pig infection, has not been carried out. Spleen samples from 16 PCV-2-positive wild pigs from hunting grounds of four regions in Germany were used for the analysis of the viral genome. In one sample, the complete sequence of the genome was determined. In the other, a 742 nucleotide fragment from the highly variable capsid sequence of the ORF2 was sequenced. Analysis of the sequences led to the identification of three PCV-2 strains. One strain, representing 14 of the 16 samples, was closely related with Chinese, but not with German strains. The genome of this strain was shortened by one nucleotide by a deletion close to the end of ORF2. The deletion led to a shift of the stop-codon and to the insertion of a further codon. Two further strains differed in up to 4.7% of nucleotides and up to 10.5% of amino acids (aa). These strains were aligned with clusters of PCV-2 samples from mainly French and German domestic origin.     

Die Scopolaminbildung in der ArtkreuzungDatura ferox L. ×Datura stramonium L.

Zusammenfassung Datura ferox enthält als Hauptalkaloid Scopolamin, da sie die Fähigkeit hat, während ihrer ganzen Lebensdauer in ihren oberirdischen Organen Hyoscyamin, das aus der Wurzel in den Sproß geleitet wird, in Scopolamin umzuwandeln. Diese Fähigkeit wird dominant vererbt, wennD. ferox mitDatura stramonium gekreuzt wird. Das Hauptalkaloid vonDatura stramonium ist Hyoscyamin, während Scopolamin nur in kleiner Menge enthalten ist. Die F₁-Bastarde sind ausgesprochene Scopolamin-Pflanzen; Hyoscyamin führen sie nur in geringer Menge. Die F₂-Generation besteht aus Individuen vom Scopolamin-Typ und solchen vom Hyoscyamin-Typ im Verhältnis 3:1.

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Summary The main alkaloid ofDatura ferox is hyoscine the plant being able to convert hyoscyamine into hyoscine in its overground organs. Hyoscyamine is formed in the roots and migrates to the aerial parts. The ability to convert hyoscyamine into hyoscine is dominant hereditary in hybrids betweenDatura ferox andDatura stramonium. The main alkaloid ofDatura stramonium is hyoscyamine,D. stramonium contains hyoscine only in a small amount. The F₁-hybrids are typical hyoscineplants, containing hyoscyamine in little amounts only. In the F₂-generation typical hyoscine plants and typical hyoscyamine plants are to be found at a rate 3:1.

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Datura ferox , ( ) . D. ferox c D. stramonium . D. stramonium , . F₁ . (F₂) ( 3:1) , , .