Vegetational changes in the Galápagos Islands during the period 1966–1973     

Ole Hamann 《Biological conservation》1975,7(1):37-59

Analysis of 12 permanent sample plots established in the Galápagos showed that introduced mammals have had a destructive influence on the vegetation; closed forest and scrub have been changed into open vegetation. The plots provide information on the regeneration ability of various types of vegetation. Scalesia forest, dominated by the endemic Scalesia pedunculata Hook. f., might under certain circumstances regenerate rapidly. Miconia scrub, dominated by the endemic Miconia robinsoniana Cogn., regenerates slowly and is consequently more vulnerable to the activities of man and introduced mammals. Arid zone vegetation, characterised especially by endemic species of Opuntia, is able to regenerate, but it is still too early to estimate how the regeneration will proceed. The suggested conservation measures include a continuation of the programme for elimination or control of introduced mammals, and a stronger control with the National Park areas on inhabited islands. Financial support is needed for the Galápagos National Park Service and the Charles Darwin Research Station to continue and enlarge the activities necessary to preserve the unique wildlife of the Galápagos Islands.  相似文献   

Die Wirkung neuartiger insektizider Mittel auf Regenwürmer     

Dr. Hans Goffart 《Journal of pest science》1949,22(5):72-74

Ohne Zusammenfassung  相似文献   

Der vegetabilische und animalische Nahrungsbereich des Hamsters (Cricetus cricetus L.)     

Dr. Hans Petzsch 《Journal of pest science》1949,22(7):107-110

Ohne Zusammenfassung  相似文献   

    

Hans Ostwald 《Forstwissenschaftliches Centralblatt》1941,63(9):193-208

Ohne Zusammenfassung  相似文献   

    

Hans Ostwald 《Forstwissenschaftliches Centralblatt》1938,60(18):561-570

Zusammenfassung Vorliegender Aufsa\ ist der vierte einer kleinen Schriftenreihe, die dem Gedenken des verstorbenen Unio.-Prof. Dr. Dr. h. c. E. Ostwald gewidmet ist und die das von ihm erworbene wissenschaftliche Gedankengut und seine Eikenntnisse, in gedrängter Kürze zusammengefa\t, wiedergeben foll. Es wird deshalb absichtlich zu sonstigen Ausführnngen, die den gleichen Gegenstand behandeln, nicht Stellung genommen.  相似文献   

Gedanken über Fragen der Erhaltung des forstlichen Grundvermögens     

Hans Ostwald 《European Journal of Forest Research》1938,60(6):184-193

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Die Neugestaltung der Forstwissenschaft in der Ostmark im Geiste des Nationalsozialismus     

Hans Schwarz 《Forstwissenschaftliches Centralblatt》1938,60(16):522-524

Ohne Zusammenfassung  相似文献   

Electrotrawling: a promising alternative fishing technique warranting further exploration          下载免费PDF全文

Maarten Soetaert  Annemie Decostere  Hans Polet  Bart Verschueren  Koen Chiers 《Fish and Fisheries》2015,16(1):104-124

In trawl fisheries, beam trawls with tickler chains, chain mats or bobbin ropes are used to target flatfish or shrimp. High fuel consumption, seabed disturbance and high discard rates are well‐known disadvantages of this fishing technique. These shortcomings are increasingly gaining international public and political attention, especially with the upcoming discard ban in Europe. The most promising alternative fishing technique meeting both the fisherman's aspirations, and the need for ecological progress is pulse fishing with electrotrawls. Here, the mechanical stimulation by tickler chains or bobbins is replaced by electrical stimulation resulting in reduced bottom contact, fuel costs and discards. Although a significant amount of research has been done on electrotrawls and their impact on marine organisms, most data were published in very diverse sources ranging from local non‐peer‐reviewed reports with a limited distribution to highly consulted international peer‐reviewed journals. Therefore, there is a clear need for a comprehensive yet concise and critical overview, covering and summarizing all these data and making these available for the scientific community. This article aims to meet the above goals by discussing the working principle of electric fields, the history of electrotrawls and their current application in the North Sea and impact on marine organisms. It is concluded by elaborating on the opportunities and challenges for the further implementation of this alternative fishing technique.  相似文献   

Untersuchungen zur ökologischen situation ostdeutscher landwirtschaftsbetriebe     

Hans Eckert  Gerhard Breitschuh  Manfred Kerschberger 《Archives of Agronomy and Soil Science》2013,59(3):165-177

Repräsentative ostdeutsche Landwirtschaftsbetriebe sind hinsichtlich ihrer Umweltverträglichkeit bewertet worden. Dazu diente eine Methode, die für ca. 30 relevante Umwelt‐Gefährdungspotentiale aus den Bereichen Düngung, Bodenschutz, Pflanzenschutzmitteleinsatz, Agrarraumgestaltung, Artendiversität, Energiebilanz und Tierbesatz kritische Umweltbelastungen formuliert und damit aktuelle Betriebsdaten wertend vergleicht.

Die Ergebnisse zeigen eine sehr differenzierte Situation. Während Stoffbelastungen mit Konsequenzen für die Nahrungsqualität weitgehend unkritisch sind, bestehen Defizite vor allem als “Altlasten”; in den Bereichen Bodenschutz und Agrarraumgestaltung.

Beziehungen zwischen Intensität und Umweltverträglichkeitsbewertung werden diskutiert.  相似文献   

Studies on pesticides based on coumarin. II. Synthesis and antifungal activity of ten 2-alkyl-7, 8-dihydro-3-hydroxynaphtho[1,2-c]chromen-6-ones     

Bharat B. Gupta  Raj V. Singh  Om P. Malik  Hans R. Kataria 《Pest management science》1987,21(1):51-55

A series of 2-alkyl-7, 8-dihydro-3-hydroxynaphtho[1,2-c]chromen-6-ones was synthesised by the condensation of ethyl 3, 4-dihydro-1-oxonaphthalene-2-carboxylate with substituted phenols in the presence of POCl₃. The compounds were characterised and tested for their toxicity towards the mycelial growth of seven phytopathogenic fungi in culture. Drechslera oryzae, Rhizoctonia solani and Colletotrichum falcatum exhibited maximum sensitivity to these compounds whereas Macro-phomina phaseolina, Fusarium solani, Alternaria alternata and Pythium aphanidermatum were less sensitive. 2-Ethyl-7, 8-dihydro-3-hydroxy-naphtho[1,2-c]chromen-6-ones possessed greatest toxicity with EC₅₀ values ranging from 0.2 to 2.5 μg ml^?1 against all fungi except A. alternata and P. aphanidermatum.  相似文献