Uptake and toxicity of copper and zinc for the African earthworm,Eudrilus eugeniae (Oligochaeta)

Growth rate change in earthworms is considered to be a suitable endpoint when determining sublethal effects. In this study we evaluated growth and maturation in the vermicomposting earthworm speciesEudrilus eugeniae as marker of sublethal toxicity of copper and zinc. We also compared routes of uptake. Apart from exposing worms experimentally for 73 days to contaminated food, a series of contact filter paper tests was also performed to determine LD₅₀ for copper and zinc. Both copper and zinc at sublethal concentrations affected growth and maturation in worms exposed to contaminated food. These worms had a copper content of 34.5 g g^–1 after 73 days and a zinc content of 184.9 g g^–1, showing a differential uptake. Copper was more toxic than zinc. Also in the contact test worms did take up more zinc than copper and the LD₅₀ (48 h) for copper was 0.011 mg cm^–2 and for zinc 0.066 mg cm^–2, which translated to body burdens of 6 g g^–1 for copper and 131 g g^–1 for zinc. Indications were that a regulatory mechanism existed for both metals. Both metals were taken up through the body wall at a relatively fast rate. This study indicated that the skin was the major route of metal uptake. This study also showed a poor relation between the two types of tests for purposes of evaluating lethality of zinc and copper.     

Competition among strains of Bradyrhizobium and vesicular-arbuscular mycorrhizae for groundnut (Arachis hypogaea L.) root infection and their effect on plant growth and yield

Summary Strains of Bradyrhizobium influenced root colonization by a species of vesicular-arbuscular mycorrhizae (VAM), and species of VAM influenced root nodulation by strains of Bradyrhizobium in pot experiments. In a field experiment, the effects of VAM on competition amongst inoculated bradyrhizobia were less evident, but inoculation with Bradyrhizobium strains increased root colonization by VAM. Certain VAM/Bradyrhizobium inoculum strain combinations produced higher nodule numbers. Plants grown without Bradyrhizobium and VAM, but supplied with ammonium nitrate (300 g ml^–1) and potassium phosphate (16 g ml^–1), produced higher dry-matter yields than those inoculated with both symbionts in the pot experiment. Inoculation with either symbiont in the field did not result in higher pod and haulm yields at harvest.ICRISAT Journal Article No. 886     

Influence of phenamiphos on the vesicular-arbuscular mycorrhizal symbiosis in Leucaena leucocephala

Summary Concentrations of phenamiphos ranging from 0 to 40 rg/g soil were established in a typical Oxisol (Tropeptic Eutrustox), inoculated or uninoculated with Glomus aggregatum. The effect of the nematicide on the development of vesicular-arbuscular mycorrhizal (VAM) symbiosis was evaluated in the greenhouse using Leucaena leucocephala as an indicator host plant. Treatment of soil with phenamiphos did not have a significant influence on the development of mycorrhizal activity measured in terms of subleaflet phosphorus concentrations. Similarly, the nematicide did not have an adverse effect on the level of mycorrhizal colonization or on the P content of shoots, as determined at the time of harvest. However, shoot dry weight was adversely influenced by phenamiphos when the chemical was applied to the uninoculated soil at 20 g/g soil or higher, and when it was applied to the inoculated soil at 40 g/g soil. It is concluded that phenamiphos is not likely to influence the growth of Leucaena or its symbiotic association with VAM fungi if the concentrations applied do not exceed levels known to suppress nematodes.Hawaii Institute of Tropical Agriculture and Human Resources Journal series No. 3146     

Distribution of two C cycle enzymes in soil aggregates of a prairie chronosequence

Knowledge of the cycling and compartmentalization of soil C that influence C storage may lead to the development of strategies to increase soil C storage potentials. The objective of this study was to use soil hydrolases and soil aggregate fractionation to explore the relationship between C cycling activity and soil aggregate structure. The prairie chronosequence soils were native prairie (NP) and agricultural (AG) and tallgrass prairies restored from agriculture in 1979 (RP-79) and 1993 (RP-93). Assays for -glucosidase (E.C. 3.2.1.21) and N-acetyl--glucosaminidase (NAGase, EC 3.2.1.30) activities were conducted on four aggregate size fractions (>2 mm, 1–2 mm, 250 m–1 mm, and 2–250 m) from each soil. There were significantly greater amounts of >2-mm aggregates in the RP-79 and RP-93 soils compared to the NP and AG soils due to rapid C accumulation from native plant establishment. Activities for both enzymes (g PNP g^–1 soil h^–1) were greatest in the microaggregate (2–250 m) compared to the macroaggregate (>2 mm) fraction; however, microaggregates are a small proportion of each soil (<12%) compared to the macroaggregates (75%). The RP soils have a hierarchical aggregate system with most of the enzyme activity in the largest aggregate fractions. The NP and AG soils show no hierarchical structure based on aggregate C accretion and significant C enzyme activity in smaller aggregates. The distribution of enzyme activity may play a role in the storage of C whereby the aggrading restored soils may be more susceptible to C loss during turnover of macroaggregates compared to the AG and NP soils with less macroaggregates.     

Effects of nitrification inhibitors on denitrification of nitrate in soil

Summary The influence of 28 nitrification inhibitors on denitrification of nitrate in soil was studied by determining the effects of different amounts of each inhibitor on the amounts of nitrate lost and the amounts of nitrite, N₂O and N₂ produced when soil samples were incubated anaerobically after treatment with nitrate or with nitrate and mannitol. The inhibitors used included nitrapyrin (N-Serve), etridiazole (Dwell), potassium azide, 2-amino-4-chloro-6-methylpyrimidine (AM), sulfathiazole (ST), 4-amino-1,2,4-triazole(ATC),2,4-diamino-6-trichloromethyl-s-triazine (CL-1580), potassium ethylxanthate, guanylthiourea (ASU), 4-nitrobenzotrichloride, 4-mesylbenzotrichloride, sodium thiocarbonate (STC), phenylmercuric acetate (PMA), and dicyandiamide (DCD).Only one of the nitrification inhibitors studied (potassium azide) retarded denitrification when applied at the rate of 10 g g^–1 soil, and only two (potassium azide and 2,4-diamino-6-trichloromethyl-s-triazine) inhibited denitrification when applied at the rate of 50 g g^–1 soil. The other inhibitors either had no appreciable effect on denitrification, or enhanced denitrification, when applied at the rate of 10 or 50 g g^–1 soil, enhancement being most marked with 3-mercapto-1,2,4-triazole. Seven of the inhibitors (potassium azide, sulfathiazole, potassium ethylxanthate, sodium isopropylxanthate, 4-nitrobenzotrichloride, sodium thiocarbonate, and phenylmercuric acetate) retarded denitrification when applied at the rate of 50 g g^–1 soil to soil that had been amended with mannitol to promote microbial activity.Reports that nitrapyrin (N-Serve) and etridiazole (Dwell) inhibit denitrification when applied at rates as low as 0.5 g g^–1 soil could not be confirmed. No inhibition of denitrification was observed when these compounds were applied at the rate of 10 g g^–1 soil, and enhancement of denitrification was observed when they were applied at the rate of 50 or 100 g g^–1 soil.     

Effect of the insecticide methidathion on agricultural soil microflora

Summary We studied the effects of the organophosphorus insecticide methidathion, at concentrations of 10, 50, 100, 200 and 300 g g^-1 in an agricultural soil, on fungi, total bacterial populations, aerobic N₂-fixing bacteria, denitrifying bacteria, nitrifying bacteria (phases I and II), and nitrogenase activity (acetylene reduction assay). The presence of 10–300 g g^-1 of methidathion significantly increased fungal populations (colony-forming units). Denitrifying bacteria, aerobic N₂-fixing bacteria and N₂ fixation were significantly increased at concentrations of 50–300 g g^-1. The total number of bacteria increased significantly at concentrations of 100–300 g g^-1. Nitrifying bacteria decreased initially at concentrations of 300 g g^-1, but recovered rapidly to levels similar to those in the control soil without the insecticide.     

Carbon and nitrogen relationships in the microbial biomass of soils in beech (Fagus sylvatica L.) forests

Soils from 38 German forest sites, dominated by beech trees (Fagus sylvatica L.) were sampled to a depth of about 10 cm after careful removal of overlying organic layers. Microbial biomass N and C were measured by fumigation-extraction. The pH of the soils varied between 3.5 and 8.3, covering a wide range of cation exchange capacity, organic C, total N, and soil C:N values. Maximum biomass C and biomass N contents were 2116 g C m^-2 and 347 g N m^-2, while minimum contents were 317 and 30 g m^-2, respectively. Microbial biomass N and C were closely correlated. Large variations in microbial biomass C:N ratios were observed (between 5.4 and 17.3, mean 7.7), indicating that no simple relationship exists between these two parameters. The frequency distribution of the parameters for C and N availability to the microflora divided the soils into two subgroups (with the exception of one soil): (1) microbial: organic C>12 mg g^-1, microbial:total N>28 mg g^-1 (n=23), a group with high C and N availability, and (2) microbial:organic C12 mg g^-1, microbial:total N28 mg g^-1 (n=14), a group with low C and N availability. With the exception of a periodically waterlogged soil, the pH of all soils belonging to subgroup 2 was below 5.0 and the soil C:N ratios were comparatively high. Within these two subgroups no significant correlation between the microbial C:N ratio and soil pH or any other parameter measured was found. The data suggest that above a certain threshold (pH 5.0) microbial C:N values vary within a very small range over a wide range of pH values. Below this threshold, in contrast, the range of microbial C:N values becomes very large.     

Seasonal changes and the effects of fertiliser on some chemical,biochemical and microbiological characteristics of high-producing pastoral soil

Summary A 2-year study (1983–1984 to 1984–1985) was conducted to estimate temporal and seasonal changes and the effects of fertiliser on some soil chemical, biochemical and microbiological characteristics. The soil used was a Typic Vitrandept under grazed pasture. Soil samples were taken regularly to a depth of 75 mm from paired unfertilised and fertilised (500 kg ha^– 30% potassic superphosphate) plots. Except for organic C, fertiliser had little or no effect on the characteristics measured. Organic C averaged about 9.2% in unfertilised soil and was about 0.3% higher in the fertilised soil. The size of the microbial biomass fluctuated widely in the 1st year (3000 g C g^–1 in February to 1300 g C g^–1 in September) but there was less variation in the 2nd year (range 1900 g C g^–1 to 2500 g C g^–1 soil). CO₂ production values (10- to 20-day estimates averaged 600 g of CO₂-C g^–1 soil) were generally higher in spring compared to the rest of the year. Water extractable C increased over winter and declined through spring in both years (range 50 g C g^–1 soil to 150 g C g^–1 soil). Mineral-N flush values were higher in summer (300 g N g^–1 soil) and lower in winter months (200 g N g^–1 soil). The pattern of variation of microbial N values was one of gradual accumulation followed by rapid decline. This rapid decline in values occurred in spring and autumn (range 130–220 g N g^–1 soil). N mineralisation and bicarbonate-extractable N showed no clear trend; these values ranged from 100–200 and 122–190 g N g^–1 soil, respectively. There was a significant correlation (0.1%) between N mineralisation and bicarbonate-extractable N in the late summer-autumn-early winter period (February–August) in both years but not in spring. These results and their relationships to climatic factors and rates of pasture production are discussed.     

Bioaccumulation of selenium by floating aquatic plants

The degree to which floating aquatic plants concentrate Se in tissues was determined for four species grown in solutions containing various levels of Se. Results of this greenhouse study showed that all four plant species, Azolla caroliniana, Eichhornia crassipes, Salvinia rotundi folia, and Lemna minor absorbed Se quickly upon exposure to Se in water as concentrated as 2.5 g Se mL^–1, and attained maximum tissue concentrations within 1 to 2 weeks. Azolla absorbed Se to the highest tissue concentration (about 1000 g Se g^–1 dry matter) from the 2.5 g Se mL^–1 solution, followed by Salvinia (700 g Se g^–1), Lemna (500 g Se g^–1),and Eichhornia (300 g Se g^–1). Plant growth appeared unaffected by solution Se concentrations lower than about 1.25 g mL^–1. These results indicate potential for rapid Se movement from water into aquatic food chains, and for use of aquatic plants for Se removal in wastewater treatment systems.     

Seasonal changes in microbial biomass and nutrient flush in forest soils

Microbial biomass and N, P, K, and Mg flushes were estimated in spring, summer, autumn, and winter samples of different forest soils. The microbial biomass showed significant seasonal fluctuations with an average distribution of 880±270 g C g^-1 soil in spring, 787±356 g C g^-1 soil in winter, 589±295 g C g^-1 soil in summer, and 560±318 g C g^-1 soil in autumn. The average annual concentrations of C, N, P, K, and Ca in the microbial biomass were 704, 106, 82, 69 and 10 g g^-1 soil, respectively. Microbial C represented between 0.5 and 2% of the organic soil C whereas the percentage of microbial N with respect to the total soil N was two-to threefold higher than that of C; the annual fluctuations in these percentages followed a similar trend to that of the microbial biomass. Microbial biomass was positively correlated with soil pH, moisture, organic C, and total N. The mean nutrient flush was 31, 15, 7, and 4 g g^-1 soil for N, K, P, and Mg, respectively, and except for K, the seasonal distribution was autumn spring winter summer. The average increase in available nutrient due to the mineralization of dead microbial cells was 240% for N, and 30, 26, and 14% for P, K, and Mg, respectively. There was a positive relationship between microbial biomass and the N, P, K, and Mg flushes. All the variables studied were significantly affected by the season, the type of soil, and the interaction between type of soil and season, but soil type often explained most of the variance.     

Molybdenum reserves of seed,and growth and N2 fixation by Phaseolus vulgaris L.

Summary Plants grown from seed with high (1.5–7.3 g Mo seed^-1) and low (0.07–1.4 g Mo seed^-1) Mo contents were grown in the presence and absence of Mo in growth media (perlite) or in a flowing-solution culture, in a controlled environment. Neither the high (1.5 g Mo seed^-1) nor the low (0.1 g Mo seed^-1) Mo content in seed from a small-seeded genotype (BAT 1297) was able to prevent Mo deficiency (reduced shoot, root and nodule dry weight, N₂ fixation and seed production) in growth media without an external supply of Mo, whereas both the high (7.3 g Mo seed^-1) and the low (0.07 g Mo seed^-1) contents in seed were able to prevent Mo deficiency in a large-seeded genotype (Canadian Wonder). Responses to Mo treatment by the Two genotypes were inconsistent between the growth media and solution culture experiments. Seed with a large Mo content (3.5 g Mo seed^-1) from the Canadian Wonder genotype was unable to prevent Mo deficiency (reduced shoot and nodule dry weight and N₂-fixation) in a solution culture without an external source of Mo, whereas both the large (1.7 g Mo seed^-1) and the small (0.13 g Mo seed^-1) contents in seed prevented a deficiency in BAT 1297. Growing plants from seed with a small Mo content, without additional Mo, reduced the seed Mo content by 83–85% and seed production by up to 38% in both genotypes. Changes in seed size and increases in shoot, root and nodule dry weight occurred, but varied with the genotype and growth conditions. These effects were also observed in some cases where plants were grown with additional Mo, demonstrating that the amount of Mo in the seed sown can influence plant nutrition irrespective of the external Mo supply. Nodule dry weight, total N content of shoots and seed production were improved by using seed with a small Mo content (1.64–3.57 g Mo seed^-1) on acid tropical soils in Northern Zambia. Plants of both the large- and small-seeded genotypes grown from seed with a small Mo content (<1.41 g Mo seed^-1) had a smaller nodule weight, accumulated less N and produced less seed. The viability of seed with a small Mo content was lower (germination up to 50% less) than that of seed with a large Mo content.     

Ergosterol and microbial biomass relationship in soil

Ergosterol and microbial biomass C were measured in 26 arable, 16 grassland and 30 forest soils. The ergosterol content ranged from 0.75 to 12.94 g g^-1 soil. The geometric mean ergosterol content of grassland and forest soils was around 5.5 g g^-1, that of the arable soils 2.14 g g^-1. The ergosterol was significantly correlated with biomass C in the entire group of soils, but not in the subgroups of grassland and forest soils. The geometric mean of the ergosterol: microbial biomass C ratio was 6.0 mg g^-1, increasing in the order grassland (5.1), arable land (5.4) and woodland (7.2). The ergosterol:microbial biomass C ratio had a strong negative relationship with the decreasing cation exchange capacity and soil pH, indicating that the fungal part of the total microbial biomass in soils increased when the buffer capacity decreased. The average ergosterol concentration calculated from literature data was 5.1 mg g^-1 fungal dry weight. Assuming that fungi contain 46% C, the conversion factor from micrograms ergosterol to micrograms fungal biomass C is 90. For soil samples, neither saponification of the extract nor the more effective direct saponification during extraction seems to be really necessary.     

Disturbance effects on soil solution chemistry due to heating cable installation

Installation of heating cables for warming soil was used to evaluate the effect of disturbance on soil solution chemistry within a northern hardwood forest (Adirondack Mountains, New York). Differences in response among treatments suggested the importance of both the depth and timing of cable installation. There were increases (p>0.05) in many solutes within pilot study plots in which surrogate cable was installed at 15 cm depth. Most notably, mean nitrate concentrations for the 1st year following disturbance were 744 eq l^-1 at 15 cm depth compared to 7 eq l^-1 for the non-disturbed control. A comparison of pilot plots with 5 cm cable depth and an unheated soil-warming control plot with the same cable disturbance showed that the seasonality of soil disturbance may have a key role in response to disturbance. The soil solution response was diminished if installation occurred during the spring, a period of rapid uptake of nitrogen by vegetation. Mean nitrate concentrations were 176 eq l^-1 for 5-cm pilot plots (installed in fall 1991) versus 6 eq l^-1 for 5-cm, unheated soil-warming control plots (installed in spring 1992). Disturbance effects were attenuated over time and not generally apparent 1 year after installation.     

Application of random amplified polymorphic DNA markers to evaluate intraspecific genetic variation in the Elymus alaskanus complex (Poaceae)

Random amplified polymorphic DNA (RAPD) markers were used to evaluatethe levels and patterns of genetic diversity in ten Elymusalaskanus populations, which were collected from Canada, USA,Greenland and Russia. Ten arbitrarily chosen decamer primers were used in thisstudy. The results revealed high levels of variation. The mean number of allelesper locus (Ap) was 1.5, ranging from 1.4 to 1.6, the meanpercent of polymorphic loci (Pp) was 49.5%, ranging from35.1% to 64.9%, and the mean gene diversity (Hep) was0.162, varying from 0.142 to 0.262. The total variation wasH _T = 0.403. When partitioned(G _ST), 60% of the total variation was foundamong the populations. Although the genetic diversity values obtained with RAPDsare much higher than for allozymes, they are similar regarding how the geneticvariation is distributed among populations. In addition, a similar geneticpattern of population differentiation, where populations from Greenland andthe USA (violaceus and latiglumis)were clearly separated from the others (hyperarcticus,komarovii and sajanensis), wasrevealed by both the cluster and principal coordinates analyses.     

Modellvorstellungen zur Kohlenstoff-Isotopendiskriminierung bei der Photosynthese von C3- und C4-Pflanzen

Zusammenfassung In der vorliegenden Arbeit werden Modelle für die Anreicherung des Kohlenstoffatoms¹²C gegenüber¹³C bei der Photosynthese von C₃- und C₄-Pflanzen beschrieben und im Zusammenhang mit Literaturdaten zum Einfluß innerer und äußerer Faktoren auf diesen Vorgang diskutiert. Bei den C₃-Pflanzen wird die Isotopendiskriminierung durch das Verhältnis der Geschwindigkeiten des Transports von CO₂ in das Blatt und der Carboxylierung des Ribulose-1,5-bisphosphats (RuBP) bestimmt. Ausdruck dieses Zusammenhangs ist eine vonFarquhar (1980) angegebene lineare Beziehung zwischen ¹³C-Wert und dem Verhältnis von interzellulärer und äußerer CO₂-Konzentration. Die Isotopendiskriminierung bei der C₄-Photosynthese ist ebenfalls von den Geschwindigkeiten der Diffusion von CO₂ in das Blatt und der primären Carboxylierung von Phosphoenolpyruvat (PEP) abhängig. Wegen der unvermeidlichen Verluste von CO₂ aus den Leitbündelscheidenzellen sind aber auch die sekundäre Carboxylierung von RuBP und der CO₂-Transport innerhalb des Blattes zu berücksichtigen. Ein auf dieser Grundlage entwickeltes Modell, das im Gegensatz zu einem früher beschriebenen Ansatz auch die CO₂-Abhängigkeit der Geschwindigkeitsparameter für die Carboxylierungsschritte einschließlich der Limitierung der PEP-Carboxylierung durch die PEP-Regenerationsrate berücksichtigt, wird ausführlich dargestellt. Nach diesem Modell können die wenigen bisher bekannten Befunde zum Einfluß hoher CO₂-Konzentrationen auf die Isotopendiskriminierung von C₄-Pflanzen als Hinweis darauf interpretiert werden, daß der Isotopeneffekt der RuBP-Carboxylierung bei den C₄-Pflanzen möglicherweise größer ist als bei den C₃-Pflanzen.

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Models of carbon isotope discrimination during photosynthesis of C₃ and C₄ plants

Summary Models of fractionation of carbon atoms¹²C and¹³C during photosynthesis of C₃ and C₄ plants are described and discussed with regard to the influence of internal and external factors on this process. Isotope discrimination in C₃ plants is determined by the ratio of the rates of CO₂ transfer into the leaf and carboxylation of ribulose-1,5-bisphosphate (RuBP). This relationship can be expressed by a linear equation between ¹³C value and the ratio of intercellular and external CO₂ concentration as proposed byFarquhar (1980). Carbon isotope discrimination by C₄ photosynthesis also depends on the rates of CO₂ diffusion into the leaf and of primary carboxylation of phosphoenolpyruvate (PEP). However, because of the unavoidable losses of CO₂ from bundle sheath cells the secondary carboxylation of RuBP as well as CO₂ transfer processes within the leaf must be taken into account, too. A model based on these features is explained in some detail. In contrast to a model proposed earlier the presented model considers the dependence on CO₂ concentration of rate parameters for the carboxylation steps including limitation of PEP carboxylation by PEP regeneration rate. According to the model the spare experimental results on the influence of high concentrations of CO₂ on carbon isotope discrimination in C₄ plants may be interpreted as an indication that the isotope effect of RuBP carboxylation in C₄ plants could be higher than in C₃ plants.

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₃ - ₄ -

^{12 13} _{3 4} , , . ₃- ₂ -1,5- (). , (1980), ¹³ ₂. _{4 2} (). ₂ , ₂ . , , , , ₂, . , , , _{2 4}-, , ₄ -, , , ₃-.

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Herrn Prof. Dr.K. Unger anläßlich der 65. Wiederkehr seines Geburtstages gewidmet.     

Contribution to the taxonomy ofVicia species belonging to the sectionFaba

Summary Vicia faba belongs to the sectionFaba. While the other species of the sectionV. narbonensis, V. johannis andV. bithynica cross enough well each other,V. faba seems to be strongly isolated from them. In addition the chromosome morphology ofV. faba differs from the other species of the section which among themselves are enough homogenous in this respect.To contribute to a wider knowledge on the taxonomical position ofV. faba in its section, electrophoretical and karyological analysis of 500 individuals belonging to 50 populations of different origin were carried out.The analyzed species were:V. faba, V. narbonensis, V. serratifolia, V. bithynica, V. galilaea andV. johannis.

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Beitrag zur Taxonomie derVicia-Arten der SektionFaba

Zusammenfassung Vicia faba gehört zur sect.Faba. Während andere Arten der Sektion (V. narbonensis, V. johannis undV. bithynica) untereinander relativ gut kreuzbar sind, istV. faba von ihnen deutlich isoliert. Darüberhinaus unterscheidet sichV. faba in der Morphologie seiner Chromosomen von den anderen Arten der Sektion, die in dieser Hinsicht eine relativ einheitliche Merkmalsausprägung zeigen. Um zu einer besseren Kenntnis der systematischen Stellung vonV. faba innerhalb der Sektion beizutragen, wurden chromatographische und karyologische Analysen von 500 Individuen aus 50 Populationen verschiedener Herkunft durchgeführt. Analysiert wurdenV. faba, V. narbonensis, V. serratifolia, V. bithynica, V. galilaea undV. johannis.

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Vicia, Faba

Vicia faba Faba. (V. narbonensis, V. johannis, V. bithynica) ,V. faba ë . ,V. faba , . V. faba , 500 50 . :V. faba, V. narbonensis, V. serratifolia, V. bithynica, V. galilaea, V. johannis.

     

Buntlaubhölzer in kollinen Waldgesellschaften Mittelthüringens

Zusammenfassung 1. Im Trias-Hügelland Mittelthüringens werden die reichen Laubmischwälder im Hinblick auf die Beteiligung seltenerer Buntlaubhölzer (Acer, Ulmus, Fraxinus, Tilia, Sorbus) an der Holzartenkombination untersucht.2. Neben unterschiedlichen Standortsansprüchen spielt das Konkurrenzverhalten der Arten — vor allem die Überlegenheit vonFagus silvatica im mesophilen Bereich bei entsprechendem Klima — eine entscheidende Rolle. Dadurch zeigen Arten mit weiter ökologischer Amplitude vielfach zwei Verbreitungsschwerpunkte, nämlich im feuchten und im trockenen Bereich, wodurch zwei ökologische Optima vorgetäuscht werden.3. BeiFraxinus excelsior ist dieses Verhalten am deutlichsten; sie fehlt jedoch auch dem mesophilen Bereich nicht vollständig. Nach ihrem ökologischsoziologischen Verhalten kann angenommen werden, daß es sich an den beiden Extremen nicht um verschiedene Ökotypen handelt. Ähnlich liegen die Verhältnisse beiQuercus robur.4. Eine geringere ökologische Spanne nehmenCarpinus betulus, Acer campestre undTilia cordata ein. Auch sie werden jedoch aus dem mesophilen Buchenbereich weitgehend verdrängt.Tilia cordata tritt auf schweren mergeligtonigen Böden am stärksten in Erscheinung, meidet dagegen trockene Kalkstandorte weitgehend. Sie reagiert am Rande des Thüringer Beckens stärker auf edaphische als auf klimatische Differenzierungen.5.Ulmus scabra, Acer platanoides, A. pseudo-platanus undTilia platyphyllos sind Elemente frischer Hangstandorte.Sorbus torminalis ist ausgesprochen thermophil mit starker Verbreitung im xerothermen Bereich.6. Die wichtigsten Waldgesellschaften, in denen Buntlaubhölzer vorkommen, werden beschrieben: Bach- und Gründchenwälder mit dominierenderFraxinus excelsior, schluchtwaldartige Edellaubholzwälder mitAcer pseudo-platanus, A. platanoides, Ulmus scabra, Tilia platyphyllos undFraxinus excelsior (mit Tabelle), ein Stieleichen-Hainbuchenwald mitQuercus robur, Fraxinus excelsior undTilia cordata, verschiedene Buchenwälder mitAcer pseudo-platanus oderTilia platyphyllos jeweils zusammen mitFraxinus excelsior, thermophile Eichen-Hainbuchenwälder mitQuercus petraea, Sorbus torminalis undAcer campestre und Elsbeer-Eichenmischwälder mitQuercus robur, Sorbus torminalis, Fraxinus excelsior und als SeltenheitQuercus pubescens. Sie bilden gegenüber der extrazonalen Steppenvegetation an extremen Hangstandorten eine natürliche Waldgrenze.

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Summary The rich broad leaved forests of the Middle-Thuringian trias hilly country were studied with regard to the participation of rarer precious woods (Acer, Ulmus, Fraxinus, Tilia, Sorbus) in the combination of the woody species.Apart from the different ecology of locality the behaviour in competition — especially the superior ability ofFagus silvatica to meet competition under corresponding climate — plays a decisive part. For that reason species with a wide ecological amplitude often have two centres of distribution, one in humid and one in dry places. In this way two ecological optimum ranges are pretended. In the case ofFraxinus excelsior, which strongly emerges in humid to wet and in the driest ranges, the ecological behaviour allows the conclusion that there are no different ecotypes.The most important forest communities in which these associate tree species exist are described. Special attention is paid to ravine-forest like structures withAcer pseudo-platanus, A. platanoides, Fraxinus excelsior, Ulmus scabra andTilia platyphyllos.

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, , , (Acer, Ulmus, Fraxinus, Tilia, Sorbus), . , — Fagus silvatica . : ; .Fraxinus excelsior, , , e ; - . , . , Acer pseudoplatanus, Acer platanoides, Fraxinus excelsior, Ulmus scabra Tilia platyphyllos.

     

Selenium in Water,Sediment, Plants,Invertebrates, and Fish in the Blackfoot River Drainage

Nine stream sites in the Blackfoot River watershed in southeastern Idaho were sampled in September 2000 for water, surficial sediment, aquatic plants, aquatic invertebrates, and fish. Selenium was measured in these aquatic ecosystem components, and a hazard assessment was performed on the data. Water quality characteristics such as pH, hardness, and specific conductance were relatively uniform among the nine sites examined. Selenium was elevated in water, sediment, aquatic plants, aquatic invertebrates, and fish from several sites suggesting deposition in sediments and food web cycling through plants and invertebrates. Selenium was elevated to concentrations of concern in water at eight sites (>5 g/L), sediment at three sites (>2 g/g), aquatic plants at four sites (>4 g/g), aquatic invertebrates at five sites (>3 g/g), and fish at seven sites (>4 g/g in whole body). The hazard assessment of selenium in the aquatic environment suggested low hazard at Sheep Creek, moderate hazard at Trail Creek, upper Slug Creek, lower Slug Creek, and lower Blackfoot River, and high hazard at Angus Creek, upper East Mill Creek, lower East Mill Creek, and Dry Valley Creek. The results of this study are consistent with results of a previous investigation and indicate that selenium concentrations from the phosphate mining area of southeastern Idaho were sufficiently elevated in several ecosystem components to cause adverse effects to aquatic resources in the Blackfoot River watershed.     

Beiträge zur Kenntnis der Vaucheriaceen XI. Vaucherien aus Tadshikistan

Zusammenfassung Aus lebendem Algenmaterial der Gegend von Duschanbe wurdenVaucheria woroniniana fo.quadripora forma nova undV. debaryana Woronin kultiviert und die Besonderheiten von Populationen verschiedener Herkünfte dieser Arten an Kulturen verglichen.

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Summary August 1963 we got samples of living algae collected some days ago in the surroundings of Duschanbe (Pamir region). Two species ofVaucheria could be identificated after developping reproductive structures in cultures:V. debaryana Woronin andV. woroniniana Heering formaquadripora fo. nov. To secure the extend of variability populations of different geographical origin were compared, grown under the same conditions. The species found are new ones for the Pamir region.

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am ¶rt;au , , Vaucheria woroniniana fo.quadripora forma nova V. debaryana Woron. , .

     

Skulpturuntersuchungen an Pollen der GattungenTriticum L. undAegilops L.

Zusammenfassung Die Exineskulptur von 42 Arten der GattungenTriticum L. undAegilops L. wurde rasterelektronenmikroskopisch untersucht. In beiden Gattungen wurden sowohl scabrate als auch areolate Skulpturen festgestellt, wobei eine unterschiedliche Zahl von Spinulae an der Bildung der Areolen beteiligt sein kann. Die Skulpturen des einzelnen Pollenkorns zeigen oft eine gewisse Variationsbreite. Die einfacheren Skulpturtypen der GattungTriticum wurden bei den diploiden und den durch ein G-Genom charakterisierten Arten beobachtet, während sich die hexaploiden Weizen durch besonders komplexe Areolenbildungen auszeichnen. Die durch das B-Genom gekennzeichneten tetraploiden Weizen nehmen eine Mittelstellung ein. Bei der GattungAegilops herrschen ebenfalls areolate Exinebildungen vor, die bei der SektionVertebrata durch einfachere, bei der SektionComopyrum durch komplexere Areolen gekennzeichnet sind. Die übrigen Sektionen dieser Gattung zeigen keine einheitliche Tendenz.

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Investigations in pollen sculpturing ofTriticum L. andAegilops L.

Summary The exine sculpturing of 42 species of the generaTriticum andAegilops has been investigated with the aid of SEM. Scabrate und areolate sculpturing has been found in both genera. Thereby the areoles may be composed of different numbers of spinules. The single pollen frequently shows some variation in the sculpture type. The most simple sculpture types of the genusTriticum has been observed in diploid species and those, which are characterized by the G-genome. The hexaploid wheats possess the most complex areoles. The exine type of the tetraploid species, characterized by the B-genome, is intermediate. Areolate exine types also prevail in the genusAegilops. The exine of the sectionVertebrata possesses more simple types of areoles, whereas the sectionComopyrum is characterized by more complex areoles. The other sections of this genus do'nt show uniform tendency.

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Triticum L. Aegilops L.

42 , Triticum L. Aegilops L. . , , , , . . Triticum , G, . , B . Aegilops , Vertebrata , Comopyrum . .