ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

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Measurements of aerobic metabolism of a school of horse mackerel at different swimming speeds (1996)

Wardle, C. S. ; Soofiani, N. M. ; O'Neill, F. G. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 49 (1996), S. 0

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ISSN: 1095-8649

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Oxygen consumption rates were measured in a school of 56 horse mackerel Trachurus trachurus while at rest and while swimming at steady sustained speeds. Resting values of 38.76 and 42.10mg O2 kg−1 h−1 were measured in a sealed cylindrical tank (535 l) while observing that the fish school remained neutrally buoyant and inactive with only gentle pectoral fin movements and no swimming motion. The same school was trained to swim with projected light patterns within a 10-m diameter annular doughnut respirometer. The oxygen consumption increased from the resting level through 51 mg O2 kg−1 h−1 at the slowest swimming speeds of 0.29 m s−1 (0.95 L s−1) to around 259 mg O2 kg−1 h−1 at the higher measured swimming speed of 0.87 m s−1 (2.82 L s−1). The data fitted a curve where oxygen consumption rose in proportion to velocity to the power of 2.56 with the intercept at the resting level. The maximum sustained speed (80 min) of 1.12 m s−1 (3.63 Ls−1) was not achieved within the respirometer but corresponded to an estimated oxygen consumption of 458.33 mg O2 kg−1 h−1 giving a scope for aerobic activity of 419.02 mg O2 kg−1 h−1. At a speed of 0.87 m s−1, there was a lower bound on the aerobic efficiency of at least 38% and at 1.12 m s−1, the highest aerobic speed, of 40%. Sustained speeds swum in a curved path as here should be increased by 5% for a straight path giving a maximum sustained 80 min speed of 1.18 m s−1.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1095-8649.1996.tb00084.x

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2

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The charcoal effect in Boreal forests: mechanisms and ecological consequences (1998)

Wardle, D. A. ; Zackrisson, O. ; Nilsson, M.-C.

Springer

Oecologia 115 (1998), S. 419-426

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ISSN: 1432-1939

Keywords: Key words Activated carbon ; Boreal forest charcoal ; Ericaceous shrubs ; Wildfire

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Wildfire is the principal disturbance regime in northern Boreal forests, where it has important rejuvenating effects on soil properties and encourages tree seedling regeneration and growth. One possible agent of this rejuvenation is fire-produced charcoal, which adsorbs secondary metabolites such as humus phenolics produced by ericaceous vegetation in the absence of fire, which retard nutrient cycling and tree seedling growth. We investigated short-term ecological effects of charcoal on the Boreal forest plant-soil system in a glasshouse experiment by planting seedlings of Betula pendula and Pinus sylvestris in each of three humus substrates with and without charcoal, and with and without phenol-rich Vaccinium myrtillus litter. These three substrates were from: (1) a high-productivity site with herbaceous ground vegetation; (2) a site of intermediate productivity dominated by ericaceous ground vegetation; and (3) an unproductive site dominated by Cladina spp. Growth of B. pendula was stimulated by charcoal addition and retarded by litter addition in the ericaceous substrate (but not in the other two), presumably because of the high levels of phenolics present in that substrate. Growth of P. sylvestris, which was less sensitive to substrate origin than was B. pendula, was unresponsive to charcoal. Charcoal addition enhanced seedling shoot to root ratios of both tree species, but again only for the ericaceous substrate. This response is indicative of greater N uptake and greater efficiency of nutrient uptake (and presumably less binding of nutrients by phenolics) in the presence of charcoal. These effects were especially pronounced for B. pendula, which took up 6.22 times more nitrogen when charcoal was added. Charcoal had no effect on the competitive balance between B. pendula and P. sylvestris, probably due to the low intensity of competition present. Juvenile mosses and ferns growing in the pots were extremely responsive to charcoal for all sites; fern prothalli were entirely absent in the ericaceous substrate unless charcoal was also present. Charcoal stimulated active soil microbial biomass in some instances, and also exerted significant although idiosyncratic effects on decomposition of the added litter. Our results provide clear evidence that immediately after wildfire fresh charcoal can have important effects in Boreal forest ecosystems dominated by ericaceous dwarf shrubs, and this is likely to provide a major contribution to the rejuvenating effects of wildfire on forest ecosystems.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050536

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3

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Microbe-plant competition, allelopathy and arctic plants (1997)

Wardle, D. A. ; Nilsson, Marie-Charlotte

Springer

Oecologia 109 (1997), S. 291-293

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ISSN: 1432-1939

Keywords: Key words Allelopathy ; Arctic plants ; Empetrum hermaphroditum ; Microbial nutrient uptake ; Nutrient acquisition

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Michelsen et al. (1995) present results of an experiment in which aqueous leaf extracts of three arctic woody plant species were found to inhibit growth and nutrient acquisition of three graminoid species, and suggested that microbial nutrient immobilisation, rather than allelopathy, was responsible for the observed trends. In doing this they also question previous work proposing that the Arctic dwarf shrub Empetrum hermaphroditum is allelopathic. We suggest that their conclusions are not unequivocally supported by their data. Firstly we indicate that the approaches used for estimating microbial nutrient immobilisation are questionable. Secondly we indicate that most of the trends that they discussed are based on data in which the treatments and controls are not significantly different for the majority of cases. Finally we respond specifically to their criticisms of previous work on E. hermaphroditum. While the question of how arctic plants interact is an interesting one, we conclude that this question cannot be answered by their data.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050086

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4

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Interactions between 14C-labelled atrazine and the soil microbial biomass in relation to herbicide degradation (1996)

Ghani, G. ; Wardle, D. A. ; Rahman, A. ; [et al.]

Springer

Biology and fertility of soils 21 (1996), S. 17-22

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ISSN: 1432-0789

Keywords: Atrazine ; Microbial biomass ; Herbicide degradation ; Basal respiration

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract A laboratory incubation experiment was set up to determine the effects of atrazine herbicide on the size and activity of the soil microbial biomass. This experiment was of a factorial design (0, 5, and 50 μg g−1 soil of non-labelled atrazine and 6.6×103 Bq g−1 soil of 14C-labelled atrazine) x (0, 20, and 100 μg g−1 soil of urea-N) x (pasture or arable soil with a previous history of atrazine application). Microbial biomass, measured by substrate-induced respiration and the fumigation-incubation method, basal respiration, incorporation of 14C into the microbial biomass, degradation of atrazine, and 14C remaining in soil were monitored over 81 days. The amount of microbial biomass was unaffected by atrazine although atrazine caused a significant enhancement of CO2 release in the non-fumigated controls. Generally, the amounts of atrazine incorporated into the microbial biomass were negligible, indicating that microbial incorporation of C from atrazine is not an important mechanism of herbicide breakdown. Depending on the type of soil and the rate of atrazine application, 18–65% of atrazine was degraded by the end of the experiment. Although the pasture soil had twice the amount of microbial biomass as the arable soil, and the addition of urea approximately doubled the microbial biomass, this did not significantly enhance the degradation of atrazine. This suggests that degradation of atrazine is largely independent of the size of the microbial biomass and suggests that other factors (e.g., solubility, chemical hydrolysis) regulate atrazine breakdown. A separate experiment conducted to determine total amounts of 14C-labelled atrazine converted into CO2 by pasture and arable soils showed that less than 25% of the added 14C-labelled atrazine was oxidised to 14CO2 during a 15-week period. The rate of degradation was significantly greater in the arable soil at 24%, compared to 18% in the pasture soil. This indicates that soil microbes with previous exposure to atrazine can degrade the applied atrazine at a faster rate.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00335988

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5

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The detritus food-web and the diversity of soil fauna as indicators of disturbance regimes in agro-ecosystems (1995)

Wardle, D. A. ; Yeates, G. W. ; Watson, R. N. ; [et al.]

Springer

Plant and soil 170 (1995), S. 35-43

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ISSN: 1573-5036

Keywords: agro-ecosystem ; diversity ; food-web ; macrofauna ; nematode ; trophic interaction

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract An ongoing study initiated in August 1990 investigated the effects of disturbances (organic mulching, cultivation, herbicides) on the detritus food-web in annual (maize) and perennial (asparagus) cropping systems. In this paper we attempt to simultaneously assess the functional and taxonomic structure of various components of this food-web. Biota in the perennial system was the most responsive to disturbance. The microflora was strongly influenced by mulching, and through tritrophic effects caused increases in top predatory but not most microbe-feeding nematodes. These effects have become increasingly apparent as the study has progressed and, in the asparagus site, have worked their way down the soil profile over time. Cultivation in the asparagus site caused large increases in bacterial-feeding nematodes, probably due to the high weed levels which developed during the winter months under that treatment. Evidence appears to exist for a cascade effect operating due to top down effects of nematodes on lower trophic levels. Ordination analysis of the nematode data demonstrated that nematode populations were more closely related to the state of environmental factors at earlier samplings than at contemporary samplings, and that the linkages between the nematode and environmental data sets strengthened over time. For both the nematode and soil-associated beetle data distinct assemblages of organisms were found in the mulched plots; distinct assemblages of nematode genera also emerged in the cultivated asparagus plots after two years. The soil-associated macrofauna was usually linked to high weed and surface organic residue levels. Species diversity of soil associated nematodes was not particularly responsive to disturbance while that of the soil-associated beetles was strongly enhanced by mulching and (sometimes) high weed levels. Approaches based on either functional group or species composition data emerged in our study as reasonably sensitive indicators for assessing the response of the soil biota to disturbance.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02183053

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6

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The “equivalent” anisotropic properties of layered rock and soil masses (1972)

Wardle, L. J. ; Gerrard, C. M.

Springer

Rock mechanics and rock engineering 4 (1972), S. 155-175

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ISSN: 1434-453X

Keywords: Anisotropy ; Elastic Theory ; Elasticity Modulus ; Isotropy ; Poisson's Ratio ; Rock Mechanics ; Soil Mechanics ; Stratification ; anisotropie ; théorie élastique ; module d'élasticité ; isotropie ; coefficient de Poisson ; mécanique des roches ; mécanique des sols ; stratification ; Anisotropie ; Elastizitätstheorie ; Elastizitätsmodul ; Isotropie ; Poissonszahl ; Felsmechanik ; Erdbaumechanik ; Schichtung

Source: Springer Online Journal Archives 1860-2000

Topics: Architecture, Civil Engineering, Surveying , Geosciences

Description / Table of Contents: Résumé Les propriétés anisotropes “équivalentes” des massifs stratifiés de roches ou de sols On examine le matériau élastique à anisotropie transversale “équivalent” à une roche ou à un sol stratifié, en supposant que chaque strate individuelle est isotrope. Il est montré qu'il existe des restrictions du domaine des variations admissibles de certaines des cinq constantes caractéristiques élastiques du matériau à anisotropie transversale le plus général. On examine plus particulièrement les cas suivants: a) Les coefficients de Poisson sont égaux dans toutes les couches, b) toutes les couches sont incompressibles et c) les modules de cisaillement sont égaux dans toutes les couches. Des abaques permettent une évaluation rapide des propriétés du milieu “équivalent” d'un grand nombre de systèmes à deux couches, facilitant ainsi l'utilisation des solutions élastiques des corps à anisotropie transversale aux milieux stratifiés.

Abstract: Zusammenfassung Die „äquivalenten“ anisotropen Eigenschaften von geschichtetem Fels und Boden Untersucht wird ein orthotropes, elastisches Material, das zu geschichtetem Fels und Boden äquivalent ist, wobei angenommen wird, daß die einzelnen Lagen isotrop sind. Es wird gezeigt, daß im Vergleich zum „allgemeinen“ orthotropen Material die zulässigen Veränderungen von einigen der fünf charakteristischen Konstanten mehr beschränkt sind. Im besonderen sind Fälle untersucht, in denen a) die Poissonzahlen in allen Schichten gleich sind, b) alle Schichten inkompressibel sind und c) die Schubmoduli in allen Schichten gleich sind. Mittels der vorgelegten Tabellen ist eine rasche Einschätzung der Eigenschaften eines äquivalenten Materials für eine Reihe zweischichtiger Systeme möglich, wodurch der Anwendungsbereich der elastischen Lösungen von homogenen, orthotropen Körpern für geschichtete Medien erleichtert werden kann.

Notes: Summary The “Equivalent” Anisotropic Properties of Layered Pock and Soil Masses The cross-anisotropic elastic material “equivalent” to stratified rock or soil is examined, assuming the individual strata to be isotropic. It is shown that there are restrictions on the ranges of permissible variation of some of the five characteristic constants compared with those of a general cross-anisotropic material. Consideration is given to the special cases in which (a) the Poisson's ratios are equal in all layers, (b) all layers are incompressible, and (c) the shear moduli are equal in all layers. Charts are presented that allow rapid assessment of the properties of the “equivalent” medium for a range of two-material systems, thus facilitating the application of the elastic solutions for homogeneous, cross-anisotropic bodies to layered media.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01597000

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7

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The effects of triethyl lead on the development of hippocampal neurons in culture (1995)

Audesirk, T. ; Shugarts, D. ; Cabell-Kluch, L. ; [et al.]

Springer

Cell biology and toxicology 11 (1995), S. 1-10

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ISSN: 1573-6822

Keywords: calcium ; hippocampal neurons ; neuronal differentiation ; organic lead ; triethyl lead

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract Triethyl lead is the major metabolite of tetraethyl lead, which is used in industrial processes and as an antiknock additive to gasoline. We tested the hypothesis that low levels of triethyl lead (0.1 nmol/L to 5μmol/L) interfere with the normal development of cultured E18 rat hippocampal neurons, possibly through increases in intracellular free calcium ion concentration, [Ca2+]in. The study assessed survival and differentiation using morphometric analysis of individual neurons. We also looked at short-term (up to 3.75-h) changes in intracellular calcium using the calcium-sensitive dye fura-2. Survival of neurons was significantly reduced at 5 μmol/L, and overall production of neurites was reduced at ≥2 μmol/L. The length of axons and the number of axons and dendrites were reduced at ≥1 μmol/L. Neurite branching was inhibited at 10 nmol/L for dendrites and 100 nmol/L for axons. Increases in intracellular calcium were observed during a 3.75-h exposure of newly plated neurons to 5 μmol/L triethyl lead. These increases were prevented by BAPTA-AM; which clamps [Ca2+]in at about 100 nmol/L. Culturing neurons with BAPTA-AM and 5 μmol/L triethyl lead did not reverse the effects of triethyl lead, suggesting that elevation of [Ca2+]in is not responsible for decreases in survival and neurite production. Triethyl lead has been shown to disrupt cytoskeletal elements, particularly neurofilaments, at very low levels, suggesting a possible mechanism for its inhibition of neurite branching at nanomolar concentrations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00769987

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8

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Book reviews (1996)

Saunders, Richard L. ; Hart, Paul J B ; Magnan, Pierre ; [et al.]

Springer

Reviews in fish biology and fisheries 6 (1996), S. 463-477

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ISSN: 1573-5184

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00164326

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9

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Use of a comparative approach to identify allelopathic potential and relationship between allelopathy bioassays and “competition” experiments for ten grassland and plant species (1996)

Wardle, D. A. ; Nicholson, K. S. ; Rahman, A.

Springer

Journal of chemical ecology 22 (1996), S. 933-948

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ISSN: 1573-1561

Keywords: Allelopathy ; bioassay ; Carduus nutans L. ; comparative approach ; correlative evidence ; forage plant ; grassland ; phytometer

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Abstract Various allelopathy bioassays were used to evaluate the allelopathic potential of 10 grassland forage species against a common test (phytometer) species,Carduus nutans L. Aqueous extracts did not influenceC. nutans germination, although radicle elongation was often severely inhibited.C. nutans was strongly affected by shoot, but not root, leachates. Decomposing ground tissue had mixed effects, and often stimulated shoot production ofC. nutans. Calculation ofR 2 (coefficient of determination) values between these results, and the results of previous experiments investigating the effects of the same 10 species onC. nutans emergence and development in field plots and glasshouse competition experiments frequently revealed strong, statistically significant relationships. Our results therefore provide correlative evidence for the importance of allelopathy in field conditions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02029946

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