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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Diversity and abundance of ants (Hymenoptera: Formicidae) in Phu Luong, Thai Nguyen province, Vietnam / Sự đa dạng và độ phong phú của các loài kiến (Hymenoptera: Formicidae) ở Phú Lương, tỉnh Thái Nguyên, Việt Nam

Nguyen, Dai Dac, Nguyen, Lien Thi Phuong 24 August 2017 (has links) (PDF)
Three different habitats: secondary forest, acacia plantation, and mixed forests on limestone, were chosen to determine and compare the ant species diversity in these habitats. A total of 24 identified species and 11 morphology species belonging to 20 genera in seven subfamilies were collected using pitfall traps from June 2014 to May 2015. The Shannon-Wiener’s species diversity index indicated that the diversity was the highest in the acacia plantation (2.08), followed by the secondary forest (1.99) and lowest in the mixed forests on limestone (1.83). There are three dominant species in the habitat (I), Pheidole noda, Odontomachus cf. monticola, and Odontoponera denticulate; four dominant species in the habitat (II), Odontoponera denticulata, Carebara diversa, Technomyrmex brunneus and Anoplolepis gracilipes; and only one dominant species in the habitat (III), Anoplolepis gracilipes. The species similarity (S) relatively low may be because of the difference vegetation and condition in the three habitats. / Đa dạng loài kiến trong ba môi trường sống khác nhau: rừng rậm thường xanh nhiệt đới, rừng keo và rừng hỗn giao trên núi đá vôi, được nghiên cứu để xác định và so sánh sự đa dạng các loài kiến trong những môi trường sống. Phương pháp nghiên cứu: sử dụng bẫy hố từ tháng 6 năm 2014 đến tháng 5 năm 2015. Đã ghi nhận được 35 loài, thuộc 20 giống, 7 phân họ. Chỉ số đa dạng loài Shannon-Wiener cho thấy rừng keo có chỉ số đa dạng cao nhất (2,08), tiếp theo là rừng rậm thường xanh nhiệt đới (1,99) và cuối cùng là rừng hỗn giao trên núi đá vôi (1,83). Có 3 loài ưu thế ở sinh cảnh (I) là Pheidole noda, Odontomachus cf. monticola và Odontoponera denticulata, bốn loài ưu thế ở sinh cảnh (II) là Carebara diversa, Technomyrmex brunneus, Odontoponera denticulate và Anoplolepis gracilipes. Ở sinh cảnh (III) chỉ có duy nhất một loài chiếm ưu thế là loài Anoplolepis gracilipes. Chỉ số tương đồng (S) tương đối thấp có thể là do sự khác nhau ở các thảm thực vật và điều kiện sống trong ba sinh cảnh.
2

Diversity and abundance of ants (Hymenoptera: Formicidae) in Phu Luong, Thai Nguyen province, Vietnam: Research article

Nguyen, Dai Dac, Nguyen, Lien Thi Phuong 24 August 2017 (has links)
Three different habitats: secondary forest, acacia plantation, and mixed forests on limestone, were chosen to determine and compare the ant species diversity in these habitats. A total of 24 identified species and 11 morphology species belonging to 20 genera in seven subfamilies were collected using pitfall traps from June 2014 to May 2015. The Shannon-Wiener’s species diversity index indicated that the diversity was the highest in the acacia plantation (2.08), followed by the secondary forest (1.99) and lowest in the mixed forests on limestone (1.83). There are three dominant species in the habitat (I), Pheidole noda, Odontomachus cf. monticola, and Odontoponera denticulate; four dominant species in the habitat (II), Odontoponera denticulata, Carebara diversa, Technomyrmex brunneus and Anoplolepis gracilipes; and only one dominant species in the habitat (III), Anoplolepis gracilipes. The species similarity (S) relatively low may be because of the difference vegetation and condition in the three habitats. / Đa dạng loài kiến trong ba môi trường sống khác nhau: rừng rậm thường xanh nhiệt đới, rừng keo và rừng hỗn giao trên núi đá vôi, được nghiên cứu để xác định và so sánh sự đa dạng các loài kiến trong những môi trường sống. Phương pháp nghiên cứu: sử dụng bẫy hố từ tháng 6 năm 2014 đến tháng 5 năm 2015. Đã ghi nhận được 35 loài, thuộc 20 giống, 7 phân họ. Chỉ số đa dạng loài Shannon-Wiener cho thấy rừng keo có chỉ số đa dạng cao nhất (2,08), tiếp theo là rừng rậm thường xanh nhiệt đới (1,99) và cuối cùng là rừng hỗn giao trên núi đá vôi (1,83). Có 3 loài ưu thế ở sinh cảnh (I) là Pheidole noda, Odontomachus cf. monticola và Odontoponera denticulata, bốn loài ưu thế ở sinh cảnh (II) là Carebara diversa, Technomyrmex brunneus, Odontoponera denticulate và Anoplolepis gracilipes. Ở sinh cảnh (III) chỉ có duy nhất một loài chiếm ưu thế là loài Anoplolepis gracilipes. Chỉ số tương đồng (S) tương đối thấp có thể là do sự khác nhau ở các thảm thực vật và điều kiện sống trong ba sinh cảnh.
3

Development of transient habitat modeling for stream Macrozoobenthos

Thepphachanh, Sengdavanh, Stamm, Jürgen 18 April 2024 (has links)
In addition to the hydromorphological pressure on the ecological conditions of free-flowing river courses, increasing water temperature is affecting the water bodies, particularly by changing freshwater community compositions. The low discharge of numerous European rivers in the dry and hot hydrological year 2022 proves this relevance. Therefore, ecological assessment tools such as habitat modeling should take these factors into account when assessing the quantity and quality of habitats. In this paper, the habitat modeling tool “Transient River Habitat Modeling for Macrozoobenthos” (TRiMM) is improved by incorporating a fuzzy logic approach and adding water temperature to the set of parameters determining habitat suitability for macrozoobenthos. Habitat-relevant parameters, including hydromorphological factors (depth, velocity, mineral and organic substrate) and a water quality factor (temperature), are combined in the habitat model so that it can more broadly characterize river physical conditions and their interactions with biological indicators. Habitat modeling employed the mentioned parameters to simulate suitability for the macrozoobenthos in a small river in central Saxony, Germany. Due to its deteriorated condition, this river was selected as a representative for thousands of kilometers of small rivers across the region, which have been restored. The model simulated the status quo of river conditions from spring to summer for three macrozoobenthos species (Ancylus fluviatilis, Ephemera danica and Gammarus fossarum). The results showed that the natural flow resulted in dynamic habitat suitability both spatially and temporally, which differs for each species. Remarkably, the five-parameter model (depth, velocity, temperature, mineral, and organic substrate) generally performed better compared to a similar model without temperature.
4

Land-use change, protected area effectiveness, and wildlife dynamics in post-Soviet European Russia

Sieber, Anika 30 May 2017 (has links)
Die Biodiversitätskrise des Anthropozäns wird vor allem durch vom Menschen bedingte Umweltveränderungen verursacht. Naturschutzgebiete sind ein globaler Eckpfeiler des Umweltschutzes und besonders wichtig für den Erhalt von Großsäugern. Fortschreitender menschlicher Einfluss sowie zunehmender Verlust und die Zerteilung von Lebensräumen innerhalb und außerhalb von Naturschutzgebieten beeinflussen deren Effektivität und Wert für den Umweltschutz stark, besonders in Zeiten sozioökonomischer und institutioneller Schocks mit reduzierten Ressourcen für den Umweltschutz. Der Zusammenbruch der Sowjetunion im Jahr 1991 war solch ein Schock und das Ziel dieser Doktorarbeit war es, besser zu verstehen, wie dieser Schock die Landnutzung, die Effektivität von Naturschutzgebieten und die Populationsdynamik von Wildtieren beeinflusst hat. Der europäische Teil Russlands bot sich deshalb als Untersuchungsgebiet an, da es eine vom Menschen stark beeinflusste Region ist, welche Lebensraum für Großsäuger aufweist sowie ein Netzwerk von Naturschutzgebieten besitzt, die über Langzeitdaten zur Biodiversität verfügen. Diese Doktorarbeit verwendete umfassende Datensätze und interdisziplinäre Ansätze, um die Veränderungen in Landnutzung, Jagddruck, Naturschutzgebieten, Lebensräumen und Populationsdynamiken von Wildtieren in post-sowjetischer Zeit zu beobachten und auszuwerten. Die Ergebnisse zeigen, dass der sozioökonomische und institutionelle Schock nach 1991 einen verringerten Landnutzungsdruck zur Folge hatte, bedingt durch die weit verbreitete Aufgabe von Landwirtschaft und generell abnehmende Raten von Waldeinschlag. Naturschutzgebiete spielten eine wichtige Rolle beim Schutz der Biodiversität und profitierten von vergrößerten Lebensräumen für Großsäuger. Wildtierpopulationsdynamiken waren in post-sowjetischer Zeit wesentlich beeinflusst von Landnutzungswandel und Jagddruck. Diese Forschungsergebnisse leisten einen wertvollen Beitrag zur Unterstützung des Biodiversitätsmonitorings. / The biodiversity crisis of the Anthropocene era is mainly caused by human-induced environmental changes such as land-use change and the overexploitation of wildlife. Protected areas are a cornerstone of the global conservation efforts and particularly important for preserving large mammals. Increasing human impact and continued loss and fragmentation of wildlife habitats inside and outside protected areas strongly affect their effectiveness and conservation value, especially during times of socio-economic and institutional shocks with reduced resources for nature conservation. The breakdown of the Soviet Union in 1991 was such a shock and the overall aim of this thesis was to contribute to a better understanding of how this shock affected land use, protected area effectiveness, and wildlife dynamics in European Russia. European Russia served as a representative area for such a study as it is a human-dominated region, which harbors large mammal species and a long-established network of scientific protected areas providing long-term biodiversity data. The overall aim of this thesis was assessed by using a broad range of data and interdisciplinary approaches to monitor and evaluate changes in land use and hunting pressure, protected areas, wildlife habitats, and species population dynamics in post-Soviet times. The results of this thesis revealed that the socio-economic and institutional shock after 1991 resulted in reduced land-use pressure due to widespread farmland abandonment and overall lowered rates of forest logging in European Russia. Protected areas played an important role in halting threats to biodiversity and benefitted from increased large mammals’ habitat within their zone of interaction. Wildlife dynamics were significantly affected by land-use change and hunting pressure in post-Soviet times. The findings of this thesis provide a valuable contribution to support biodiversity monitoring and overcome knowledge gaps on biodiversity conservation.

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