Response of planted beech (Fagus sylvatica L.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) saplings to herbaceous and small shrubs control on clearcuts

The reaction of young beech (Fagus sylvatica L.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) saplings on competition of two types of vegetation—(1) gramineous with mainly Agrostis capillaries, Calamagrostis epigejos, Deschampsia flexuosa, and (2) small shrubs with mainly Rubus fruticosus and R. idaeus—on clear cuts on two sites was studied for 2 years. Half the sample saplings were released from competing vegetation by repeated herbicide applications. This treatment significantly raised the diameter increment in both species at the site with higher competition intensity, and more strongly after the removal of small shrubs than after the removal of grasses. Sapling length increment was not significantly affected. After being released from small shrubs, saplings of both species developed a smaller specific fine root length (cm g⁻¹ fine root biomass) than unreleased saplings during the second year which was characterized by low rainfall. Root nitrogen concentration significantly increased after weed control in both vegetation types. Sapling foliar content of main nutritional elements was negatively related to dry mass and total chemical content of surrounding ground vegetation. Based on these results, a release from ground vegetation could be a useful tool to improve growth of planted beech and Douglas-fir saplings on sites with well-developed small shrubs competition (mainly by Rubus fruticosus and R. idaeus), or under fairly dry conditions.     

Evaluation of computer-aided learning illustrated by the multimedia program, "Hereditary diseases of the dog--joints,bones, musculature"

Results are presented on the evaluation of the interactive tutorial and information system "Hereditary diseases of the dog-joints, bones, musculature" which was developed at the Institute of Animal Breeding and Genetics and the Clinic for Small Animals at the School of Veterinary Medicine Hannover, aiming to improve the problem consciousness for the genetic background of most diseases of the musculoskeletal system of the dog. It addresses veterinarians, students of veterinary medicine and also dog breeders and owners. The programme offers extensive basic information about all known hereditary diseases of the joints, bones and muscles of the dog and gives also information on symptoms, diagnosis, therapy, distribution and genetics of the diseases. The user can apply it as a reference book, as a tutorial to complete or control his knowledge or to gain a fast overview of the up-to-date knowledge. The tutorial was evaluated by students in the second and third academic year, veterinary surgeons and dog breeders. Computer assisted learning was judged as very positive by all test persons. The programme received from all test persons an average score of 2.11 +/- 0.77 on a scale from 1 (very good) to 5 (unsatisfactory). The results show that computer-aided learning can be an effective and stimulating substitution to traditional learning and learning materials.     

Chronic intestinal pseudo-obstruction in a dog

SUMMARY A three-year-old neutered female Border Collie was presented with in-appetence, vomiting and diarrhoea. Abdominal radiographs revealed an obstructive pattern but no physical obstruction was evident at laparotomy. A diagnosis of chronic intestinal pseudo-obstruction was made based on histopathological changes in intestinal biopsies. Treatment was unsuccessful and the dog deteriorated progressively until euthanased five weeks after presentation.     

Reducing the impact of blue mussel (Mytilus edulis) dredging on the ecosystem in shallow water soft bottom areas

• Dredging blue mussels (Mytilus edulis) and thus removing structural elements, inducing resuspension of sediment as well as reducing filtration capacity, will inevitably affect the ecosystem. The study demonstrates that the impacts of fishing can be reduced through gear developments.
• A new light dredge was tested on commercial vessels using two different experimental setups. First, a twin haul experiment tested the standard gear (i.e., a Dutch dredge) against the light dredge by fishing the two gears side by side onboard the same vessel. Second, a single dredge experiment tested the absolute performance of the two gears by fishing in areas with a known blue mussel density.
• Results from the twin haul experiment demonstrate that the weight of sediment retained in the gear per square metre fished is 49% less in the light dredge compared with the Dutch dredge which will reduce resuspension of sediment at the surface. Also, the drag resistance of the light dredge was significantly less (177.1 vs. 202.7 kg m^‐1). In the twin haul experiment no significant difference was found in the catch per unit effort (CPUE) of the two gears. The single dredge experiment, on the other hand, demonstrated a significant increase in CPUE exceeding 200% when using the light dredge.
• Seafloor tracks made by the two dredges could not be distinguished by use of side‐scan sonar and the tracks were still detectable 2 months after fishing.
• It was concluded that replacement of the Dutch dredge with the light dredge would reduce the impact of the fishery on the ecosystem by (i) reducing resuspension of sediment, (ii) reducing fuel consumption, and (iii) potentially reducing energy transfer to the sediment through a reduced gear drag resistance. A potential increase in catch efficiency may reduce the area affected.
• Fishing with the light dredge is discussed in relation to management of Natura 2000 sites.

Copyright © 2014 John Wiley & Sons, Ltd.     

刈牧后休闲期对草地牧草生产的影响

通过不同间隔时期对多年生黑麦草、白三叶混播草地牧草产量的监测与分析,得出随着休闲期的增加,青绿物质和死亡物质均呈现上升趋势,在较低和较高草地牧草现存量下都会降低牧草生长率。     

贵州足球场草坪建植及化管理模型研究

在一定的生境和管理条件下,以修剪高度、修剪次数和施N、P、K量为因素,利用二次正交回归设计,用模糊综合评分法评定草坪质量,最佳3因子水平为:修剪高度5～7.4cm,修剪次数4～6次/月,施N量为2.5～3.7g/(m2·年),施P、K量各为L25～1.85g/(m2·年),建立了草坪质量与养护3因子间的显著相关回归模型.     

Relative Contributions of Uranium, Thorium, and Potassium to Heat Production in the Earth

Data from a wide variety of igneous rock types show that the ratio of potassium to uranium is approximately 1 X 10(4). This suggests that the value of K/U approximately 1 X 10(4) is characteristic of terrestrial materials and is distinct from the value of 8 X 10(4) found in chondrites. In a model earth with K/U approximately 10(4), uranium and thorium are the dominant sources of radioactive heat at the present time. This will permit the average terrestrial concentrations of uranium and thorium to be 2 to 4.7 times higher than that observed in chondrites. The resulting models of the terrestrial heat production will be considerably different from those for chondritic heat production because of the longer half-life of U(238) and Th(238) compared with K(40).     

L'influence de la temperature sur la morphologie de la pomme de terre

Résumé La morphologie duSolanum tuberosum, variétésGineke etMajestic a été étudiée dans un milieu conditionné avec des températures de 15, 20 et 25°C. En changeant la température, la plante présente des variations remarquables, soit dans l'aspect de la tige, soit dans la forme et la grandeur des feuilles. Les différences remarquées sont probablement liées à la différente fa?on de développement et de différenciation des méristèmes à cause de la température. Ils correspondaient avec les caractéristiques morphologiques et anatomiques des plantes poussant en Italie à des niveaux respectifs de 1700, 1100 et 400 m avec des températures moyennes respectivement comparables. Les remarquables différences morphologiques observées permettent de suivre les étappes de développement de la plante, et d'en juger l'age physiologique.

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Summary In order to list and study the morphological characters of the haulm ofSolanum tuberosum var.Majestic grown in different environments in Italy (Scaramella Petri 1956, 1958, 1959) tubers were planted at the I.B.S., Wageningen, in glasshouses held at 15, 20 and 25 respectively. Other tubers from the same lot were planted in Italy, in the plain near Bologna. All leaves from base to apex of the stem were numbered, dried, laid out on flat sheets and their morphology compared. Histological studies were made on sections of stem taken at predetermined levels: at the basal node, at quarter height and at the apex. Similar studies were made on the varietyGineke under the same conditions and using the same characters (fig. 3, 5). The modifications arising from growth at the three temperatures are in general the same as those shown by the varietyMajestic, but the latter is more sensitive and, therefore, more suited to studies of this kind. Leaf size Mean leaf size is greatest at 15°C; this can be explained by the greater length of the midrib. The number of leaves increases only slightly and that towards the end of the vegetative period (fig. 2,table). General morphology of the plant Similar morphological studies were done in Italy in the same year, on plants grown from the same seed. Plants grown between April and June were subjected to a temperature of 20°C during their early development; this was followed by conditions typical of the region. The mean temperature during the final period of growth was 25°C. The morphological characters of these plants resemble those of the plants grown in the 25°C glasshouse. The leaves are compound and pointed and their size diminishes gradually; the stem is tall and branched. Internal structure also presents similarities (fig. 6, 7). Morphological characters resembling those of the plants grown at 15°C can be found in the plants grown at the intermediate level in the mountains (fig. 1). These observations confirm the results of previous work and indicate clearly the effect of temperature on the morphology of the haulm. Other factors remaining constant, there is for any particular level of temperature a fixed morphological type and rate of development. In general, increased height of stem through the formation of new nodes is reflected in poorer growth below ground, both in yield of tubers and in their capacity to sprout. These observations confirm those ofWent (1959) andTizio et al. (1954) who noted that high temperatures reduced the capacity of the crop to sprout. Bearing these points in mind, it will be possible, on the basis of the form and size of the stem and leaves, to deduce the conditions under which the crop was grown and, indirectly, to forecast the capacity of the tubers to sprout. Stem size At 15°C, increase in length of stem occurs only during the final period of growth. That this increase is usually due to an extension of the internodes is shown by the constant number of nodes present during the major part of the vegetative period. Leaf form The juvenile form is found in plants grown at 15°C. It occurs not only in the lower leaves, which continue to grow, but also in the upper leaves which retain to the apex the dominance of the apical leaflet, which is rounded (fig. 2, 3). At 20°C the lowest leaves are of the juvenile form but above this they very rapidly become composite. The dominance of the apical leaflet is lost in the highest part of the stem. At 25°C the lowest leaves are juvenile in type but above this they very rapidly become elongate and composite. The pointed apical leaflet ceases to be dominant and in contrast becomes smaller and dentate. This confirms that the form of the first leaves is a clonal character whereas their subsequent development is related to the environment. In effect, all the plants started their development at 20°C but while extension of the midrib followed in plants grown at 15°C, it did not do so at 25°C. On the other hand, the form of the other leaves and their relative size is directly related to the ambient temperature.

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Zusammenfassung Zur Kontrolle und zum besseren Verst?ndnis der morphologischen Charakteristik der oberirdischen Teile vonSolanum tuberosum, SorteMajestic, die in Italien in ?kologisch verschiedener Umwelt (Scaramella Petri, 1956, 1958, 1959) angebaut wird, hat man in Glash?usern des I.B.S. in Wageningen Knollen dieser Sorte bei Temperaturen von 15, 20 bzw. 25°C ausgepflanzt. Ein Teil dieser Knollen wurde vorher in Italien an einem in der Ebene bei Bologna gelegenen Ort erzeugt. S?mtliche Bl?tter des Stengels zwischen Basis und Spitze wurden kontrolliert und ihre Morphologie wurde in vergleichender Weise studiert, indem alle getrockneten Bl?tter in Schalen gelegt wurden. Die histologischen Untersuchungen wurden an Stengelschnitten in bestimmter H?he vorgenommen: Basisknoten, Viertel und Spitze. Zum Vergleich wurden entsprechende Versuche unter gleichen Bedingungen mit der SorteGineke (abb. 3, 5) durchgeführt. Die bei der SorteGineke festgestellten Ver?nderungen unter der Einwirkung der drei Temperaturen sind in der Hauptsache gleich wie bei der SorteMajestic. Die letztere ist aber viel empfindlicher und eignet sich sehr gut für Studien dieser Art. Gr?sse der Bl?tter Die durchschnittliche Gr?sse der Bl?tter ist bei 15 am gr?ssten. Dies drückt sich durch eine gr?ssere L?nge der Blattspreite aus. Die Zahl der Bl?tter erh?ht sich nur in der letzten Vegetationsperiode leicht (abb. 2,tabelle). Allgemeine Morphologie der Pflanze Gleiche morphologische Studien wurden im selben Jahr in Italien an Pflanzen durchgeführt, die von diesen Knollenmustern stammten. Die zwischen April und Juni angepflanzten Stauden entwickelten sich zuerst bei Temperaturen von zirka 20°C. Schliesslich war die letzte Periode, unter den besonderen klimatischen Bedingungen der Gegend, durch eine mittlere Temperatur von 25 gekennzeichnet. Die morphologischen Eigenschaften dieser Pflanzen glichen stark jenen der Pflanzen, die im Glashaus bei 25°C wuchsen. Die Bl?tter sind zusammengesetzt und zugespitzt, und ihre Gr?sse nimmt stufenweise ab; der Stengel ist hoch und verzweigt. Auch die innere Struktur zeigt diese ?hnlichkeiten (abb. 6, 7). Wenn man einen Vergleich anstellen will zwischen den bei 15 gehaltenen Pflanzen, stellt man fest, dass ihre Morphologie jener der Pflanzen in den Bergen gleicht (abb. 1). Diese Feststellungen best?tigen die früheren Arbeiten und bestimmen genau den Einfluss der Temperatur auf die Morphologie der oberirdischen Partie. Gleichbleibenden andern Bedingungen entspricht bei jeder Temperatur?nderung eine gleichbleibende Morphologie und eine schnelle Entwicklung des oberirdischen Teiles. Im allgemeinen ist das L?ngenwachstum des Stengels durch Bildung neuer Knoten im Gegensatz zu jenem des unterirdischen Teiles, und die Bildung von Knollen und ihre Keimkraft sind schw?cher. Diese Beobachtungen stimmen überein mit jenen vonWent (1959) und vonTizio et al. (1954), die festgestellt haben, dass bei hohen Temperaturen Knollen mit schwacher Keimkraft gebildet werden. Wenn man diesen Beobachtungen Rechnung tr?gt, wird es m?glich sein, von der Form des Stengels und der Bl?tter und ihrer Gr?sse auf die Umweltsbedingungen, unter denen die Pflanze gewachsen ist, zu schliessen und indirekt die Keimeigenschaften der Knollen vorauszubestimmen. Gr?sse des Stengels Bei einer Temperatur von 15°C verl?ngert sich der Stengel erst w?hrend der letzten Entwicklungsperiode. Diese Verl?ngerung ist, wie die Best?ndigkeit der Knotenzahl w?hrend eines guten Teils der Vegetationsperiode zeigt, meistens durch die internodiale Verl?ngerung bestimmt. Blattform Die Jugendform findet man unter den Pflanzen, die bei 15°C kultiviert werden. Man trifft sie nicht nur in den ersten Bl?ttern an, die weiterwachsen, sondern auch in den oberen Bl?ttern, die bis zur Spitze die Dominanz des Endfiederblattes, das abgerundet ist, bewahren (abb. 2, 3). Bei 20°C gleichen die ersten Bl?tter der Jugendform, aber sehr bald werden die Bl?tter zusammengesetzt. Die Dominanz des Endfiederblattes verliert sich im obersten Teil des Stengels. Bei 25°C weisen die ersten Bl?tter die Jugendform auf, aber sehr bald erscheint die zusammengesetzte, l?ngliche Form. Das zugespitzte Endfiederbl?ttchen h?rt auf vorzuherrschen, es wird im Gegenteil kleiner und zackig. Dies best?tigt, dass die Form der ersten Bl?tter klonal vererbt wird, w?hrend die endgültige Entwicklung von der Umwelt abh?ngt. In der Tat haben alle Pflanzen bei 20°C gekeimt, aber w?hrend das Wachstum der Blattspreite bei den Pflanzen, die bei einer Temperatur von 15°C gehalten wurden, andauerte, h?rte es bei 25°C auf. Dagegen h?ngt die Form der andern Bl?tter und ihre relative Gr?sse direkt von der Temperatur der Umgebung ab.

     

Ein weiterer Beitrag zum Fichtenwachstum im n?rdlichen Rheinland-Pfalz

Ohne Zusammenfassung