Knowledge Resource Center for Ecological Environment in Arid Area
| Anthropogenic impact on predator guilds and ecosystem processes : Apex predator extinctions, land use and climate change | |
| Pasanen Mortensen;Marianne | |
| 出版年 | 2014 |
| 学位授予单位 | Stockholms universitet, Zoologiska institutionen, Stockholm : Department of Zoology, Stockholm University |
| 英文摘要 | Humans affect ecosystems by changing species compositions, landscape and climate. This thesis aims to increase our understanding of anthropogenic effects on mesopredator abundance due to changes in apex predator status, landscape and climate. I show that in Eurasia the abundance of a mesopredator, the red fox (Vulpes vulpes), is limited top-down by the Eurasian lynx (Lynx lynx) and bottom-up by winter severity. However, where lynx has been eradicated, fox abundance is instead related to bottom-factors such as cropland (paper I, II). Fox abundance was highest when croplands constituted 25% of the landscape (paper II). I also project red fox abundance in Sweden over the past 200 years and in future scenarios in relation to lynx density, land use and climate change. The projected fox abundance was highest in 1920, when lynx was eradicated and the proportion of cropland was 22%. In 2010, when lynx had recolonised, the projected fox abundance was lower than in 1920, but higher than in 1830. Future scenarios indicated that lynx abundance must increase in respond to climate change to keep fox at the same density as today. The results suggest a mesopredator release when lynx was eradicated, boosted by land use and climate change, and that changes in bottom-up factors can modify the relative strength of top-down factors (paper IV). From 1846-1922, lynx, wolverine (Gulo gulo) and grey wolf (Canis lupus) declined in Scandinavia due to persecution; however I show that the change in wolverine abundance was positively related to the changes in lynx and wolf abundance. This indicates that wolverine is subsidized by carrions from lynx and wolf kills rather than limited top-down by them (paper III). This thesis illustrates how mesopredator abundance is determined by a combination of top-down and bottom-up processes, and how anthropogenic impacts not only can change the structures of predator guilds, but also may modify top-down processes through changes in bottom-up factors. At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper 4: Manuscript. |
| 英文关键词 | Mesopredators Apex predators Top-down Bottom-up Interspecific killing Red fox Eurasian lynx Grey wolf Wolverine Productivity Winter severity Cropland Zoology Zoologi Ecology Ekologi |
| 语种 | 英语 |
| URL | http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-100720 |
| 来源机构 | Stockholms universitet |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/248890 |
| 推荐引用方式 GB/T 7714 | Pasanen Mortensen;Marianne. Anthropogenic impact on predator guilds and ecosystem processes : Apex predator extinctions, land use and climate change[D]. Stockholms universitet, Zoologiska institutionen, Stockholm : Department of Zoology, Stockholm University,2014. |
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