東華大學圖書館 |

Assessing Defaunation in the Central Annamites Ecoregion of Vietnam and Laos.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Assessing Defaunation in the Central Annamites Ecoregion of Vietnam and Laos./
作者:	Tilker, Andrew.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
面頁冊數:	145 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-08, Section: B.
Contained By:	Dissertations Abstracts International82-08B.
標題:	Ecology. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28352992
ISBN:	9798569985722

Assessing Defaunation in the Central Annamites Ecoregion of Vietnam and Laos.
Tilker, Andrew.

Assessing Defaunation in the Central Annamites Ecoregion of Vietnam and Laos. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 145 p.

Source: Dissertations Abstracts International, Volume: 82-08, Section: B.

Thesis (D.Sc.)--Freie Universitaet Berlin (Germany), 2020.

This item must not be sold to any third party vendors.

Southeast Asia is a global biodiversity hotspot, but anthropogenic threats are causing loss of larger vertebrate species (defaunation) across the region. Both habitat alteration and unsustainable hunting have contributed to defaunation in Southeast Asia. Defaunation is particularly severe in the Annamites ecoregion of Vietnam and Laos PDR, where widespread indiscriminate snaring for the illegal wildlife trade has decimated ground-dwelling mammal and bird species. Several Annamite endemics are now facing imminent extinction as a result of this snaring crisis. To develop more effective conservation strategies to protect biodiversity in Southeast Asia, it is necessary to better understand the defaunation process, and to have an accurate assessment of biodiversity in defaunated areas. The aim of this thesis was to improve our understanding of how defaunation impacts tropical faunal communities in Southeast Asia, with a specific focus on the Annamites ecoregion, thereby providing insights that can help inform conservation strategies to prevent further defaunation in tropical hotspots. Scientists have an incomplete understanding of how different defaunation drivers impact faunal communities at large spatial scales. To investigate this issue, we collected landscape-scale camera-trapping data from two study areas with fundamentally different threats: habitat degradation (Malaysian Borneo) and indiscriminate snaring (Annamites). We used a defaunation index and occupancy models to assess how defaunation differentially impacts ground-dwelling mammal and bird communities in these regions (chapter 2). We found that, while both defaunation drivers negatively impact faunal communities, the hunted sites had higher levels of functional extinction, lower species occupancies, and species distributions that were primarily influenced by anthropogenic- rather than habitat-based measures. We conclude that intensive, indiscriminate hunting may be a more severe short-term threat to terrestrial mammal and bird species than moderate levels of habitat degradation. To optimize the use of limited conservation resources, it is often necessary to understand the spatial patterns of defaunation. However, accurately assessing biodiversity in defaunated tropical forests brings a unique set of challenges. We combined camera-trapping and leech-derived data from landscape-scale surveys with advanced statistical modelling techniques and innovative explanatory covariates to assess defaunation patterns in a central Annamites forest complex that has been subjected to high levels of snaring pressure (chapter 3). Our findings show that, despite severe levels of defaunation, conservation-priority species still persist, albeit at extremely low occupancies. Threatened and endemic species were primarily found at higher elevations and in more remote areas. The results provide information that can be used to inform targeted enforcement efforts in this landscape. Understanding how defaunation impacts individual species is important to developing effective conservation strategies. Such information is especially important for species that are understudied but occur in areas known to be under extreme anthropogenic pressure. We used data from landscape-scale camera-trapping in the central Annamites to investigate the ecology and distribution of the Annamite striped rabbit Nesolagus timminsi (chapter 4). We found that Annamite striped rabbit occupancy was best explained by a proxy for past hunting pressure, which likely indicates that populations have been negatively impacted by industrial snaring. We also found that that local abundance estimates were low at one site, and that the species is likely absent from a second site where hunting pressure appears to have been more intense. Our findings provide information on priority areas to target snare-removal efforts, and the first conservation baseline for the species.

ISBN: 9798569985722Subjects--Topical Terms:

516476
Ecology.
Subjects--Index Terms:

Defaunation

Assessing Defaunation in the Central Annamites Ecoregion of Vietnam and Laos.
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500 $a Advisor: Hofer, Heribert.
502 $a Thesis (D.Sc.)--Freie Universitaet Berlin (Germany), 2020.
506 $a This item must not be sold to any third party vendors.
520 $a Southeast Asia is a global biodiversity hotspot, but anthropogenic threats are causing loss of larger vertebrate species (defaunation) across the region. Both habitat alteration and unsustainable hunting have contributed to defaunation in Southeast Asia. Defaunation is particularly severe in the Annamites ecoregion of Vietnam and Laos PDR, where widespread indiscriminate snaring for the illegal wildlife trade has decimated ground-dwelling mammal and bird species. Several Annamite endemics are now facing imminent extinction as a result of this snaring crisis. To develop more effective conservation strategies to protect biodiversity in Southeast Asia, it is necessary to better understand the defaunation process, and to have an accurate assessment of biodiversity in defaunated areas. The aim of this thesis was to improve our understanding of how defaunation impacts tropical faunal communities in Southeast Asia, with a specific focus on the Annamites ecoregion, thereby providing insights that can help inform conservation strategies to prevent further defaunation in tropical hotspots. Scientists have an incomplete understanding of how different defaunation drivers impact faunal communities at large spatial scales. To investigate this issue, we collected landscape-scale camera-trapping data from two study areas with fundamentally different threats: habitat degradation (Malaysian Borneo) and indiscriminate snaring (Annamites). We used a defaunation index and occupancy models to assess how defaunation differentially impacts ground-dwelling mammal and bird communities in these regions (chapter 2). We found that, while both defaunation drivers negatively impact faunal communities, the hunted sites had higher levels of functional extinction, lower species occupancies, and species distributions that were primarily influenced by anthropogenic- rather than habitat-based measures. We conclude that intensive, indiscriminate hunting may be a more severe short-term threat to terrestrial mammal and bird species than moderate levels of habitat degradation. To optimize the use of limited conservation resources, it is often necessary to understand the spatial patterns of defaunation. However, accurately assessing biodiversity in defaunated tropical forests brings a unique set of challenges. We combined camera-trapping and leech-derived data from landscape-scale surveys with advanced statistical modelling techniques and innovative explanatory covariates to assess defaunation patterns in a central Annamites forest complex that has been subjected to high levels of snaring pressure (chapter 3). Our findings show that, despite severe levels of defaunation, conservation-priority species still persist, albeit at extremely low occupancies. Threatened and endemic species were primarily found at higher elevations and in more remote areas. The results provide information that can be used to inform targeted enforcement efforts in this landscape. Understanding how defaunation impacts individual species is important to developing effective conservation strategies. Such information is especially important for species that are understudied but occur in areas known to be under extreme anthropogenic pressure. We used data from landscape-scale camera-trapping in the central Annamites to investigate the ecology and distribution of the Annamite striped rabbit Nesolagus timminsi (chapter 4). We found that Annamite striped rabbit occupancy was best explained by a proxy for past hunting pressure, which likely indicates that populations have been negatively impacted by industrial snaring. We also found that that local abundance estimates were low at one site, and that the species is likely absent from a second site where hunting pressure appears to have been more intense. Our findings provide information on priority areas to target snare-removal efforts, and the first conservation baseline for the species.
520 $a Sudostasien ist ein globaler Biodiversitats-Hotspot. Anthropogene Bedrohungen fuhren jedoch derzeit zu einem starken Verlust groserer Wirbeltiere (Defaunation) in der gesamten Region. Sowohl Lebensraumveranderungen als auch eine nicht nachhaltige Bejagung haben zur Defaunation Sudostasiens beigetragen. Im Truong-Son Gebirge in Vietnam und Laos ist die Lage besonders gravierend. Hier hat die weit verbreitete und wahllose Jagd mit Drahtschlingen fur den illegalen Wildtierhandel die bodenbewohnende Saugetier- und Vogelarten stark dezimiert. Mehrere endemische Arten des Truong-Son Gebirges stehen bereits kurz vor der Ausrottung. Um wirksamere Strategien zum gezielten Schutz der biologischen Vielfalt in Sudostasien zu entwickeln, ist es notwendig, den Prozess des Artenverlusts besser zu verstehen, sowie einen detaillierten Uberblick uber das derzeitige Artenvorkommen zu haben. Ziel dieser Arbeit war es, zu untersuchen wie sich die Defaunation auf die tropischen Artengemeinschaften Sudostasiens - mit besonderem Augenmerk auf das zentrale Truong-Son Gebirge - auswirkt. Des Weiteren sollte diese Arbeit erste Informationen uber das raumliche Vorkommen einiger stark bedrohter, endemischer Arten liefern, um somit gezieltere Schutzmasnahmen zu unterstutzen. Zurzeit besteht nur eine unvollstandige Kenntnis davon, wie sich verschiedene Faktoren die zur Defaunation beitragen, auf Artengemeinschaften in groseren raumlichen Masstaben auswirken. Um dies zu untersuchen sammelten wir grosskalig Kamerafallendaten aus zwei Regionen in Sudostasien, die durch grundlegend unterschiedliche Einflussfaktoren bedroht werden (Kapitel 2): Im Malaysischen Teil von Borneo ist die Artengemeinschaft primar durch die Degradadirung des Regenwaldes bedroht, wohingegen im Truong-Son Gebirge die Jagd mit Drahtschlingen die Hauptbedrohung darstellt. Mit modernen multi-species occupancy Modellen und einem Defaunation-Index konnten wir feststellen, dass sowohl Walddegradation, als auch Wilderei negative Auswirkungen auf die Artengemeinschaften haben. Jedoch zeigten unsere Ergebnisse auch, dass Arten in den illegal bejagten Gebieten nicht nur ein deutlich hoheres Aussterberisiko hatten, sondern auch, dass die Verbreitung der noch vorkommenden Arten durch die intensive Jagd viel starker zuruckgegangen ist, als die Verbreitung ihrer Schwesterarten in den durch kommerzielle Forstwirtschaft degradierten Regenwaldern. Mit diesen Ergebnissen konnten wir sehr deutlich zeigen, dass die intensive, wahllose Wilderei im Vergleich zur Walddegradation momentan die schwerwiegendere Bedrohung fur bodenlebende Saugetier- und Vogelarten darstellt. Aufgrund begrenzter finanzieller und personeller Ressourcen fur den Artenschutz ist es notwendig Masnahmen gegen Wilderei gezielt dort einzusetzen, wo noch letzte Populationen der stark bedrohten Arten vorkommen. Dafur ist es wichtig die raumlichen Muster der Defaunation zu verstehen, was jedoch in tropischen Regenwaldern eine Reihe von Herausforderungen mit sich bringt. Um Vorkommensnachweise auch von besonders seltenen Arten zu bekommen, haben wir deshalb Kamerafallendaten und molekulargenetische Nachweise aus Umwelt-DNA-Proben (Blutegeln) kombiniert (Kapitel 3). Mittels multi-species occupancy Modellen konnten wir dann die raumliche Verteilung der Arten grosflachig uber funf benachbarte Untersuchungsgebiete modellieren. Unsere Ergebnisse zeigten, dass trotz der starken Wilderei einige hochgradig bedrohte Arten noch immer im Untersuchungsgebiet vorkommen. Bedrohte und endemische Arten wurden vor allem in hoheren Lagen und in entlegenen Gebieten gefunden. Unsere Ergebnisse lieferten unseren Naturschutzpartnern wichtige Informationen, um ihre Schutzpatrouillen gezielter einsetzen zu konnen. Fur die Entwicklung wirksamer Arterhaltungsstrategien ist es zudem wichtig zu verstehen, wie sich die Defaunation auf einzelne Arten auswirkt. Solche Informationen sind besonders fur Arten wichtig, die nur wenig erforscht sind, jedoch in Gebieten vorkommen die besonders von Wilderei bedroht sind. Wir nutzten Kamerafallendaten des zentralen Truong-Son Gebirges, um die Okologie und Verbreitung des Annamiten-Streifenkaninchens Nesolagus timminsi zu untersuchen (Kapitel 4). Es zeigte sich, dass sich das Vorkommen des Annamiten-Streifenkaninchens wahrscheinlich mit dem vergangenem Jagddruck erklaren lasst und die Population durch diese intensive Wilderei mit Drahtschlingen bereits negativ beeinflusst wurde. Unsere Ergebnisse stellen den ersten grosflachigen Referenzdatensatz uber die Verbreitung des Annamiten-Streifenkaninchens dar und geben Hinweise auf Gebiete in denen bevorzugt und gezielt Drahtschlingen beseitigt werden sollten.
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653 $a Laos
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