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Land cover effects on mesopredator abundance in the presence and absence of apex predators
Stockholm University, Faculty of Science, Department of Zoology.
Stockholm University, Faculty of Science, Department of Zoology.
Number of Authors: 2
2015 (English)In: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 67, 40-48 p.Article in journal (Refereed) Published
Abstract [en]

Trophic downgrading due to loss of apex consumers has been detected in many ecosystems. Loss of larger predators implies that medium-sized mesopredators rise to the status of apex predators which are limited bottom-up rather than top-down. Hence the density of medium-sized predators should be more strongly related to land cover in absence of larger predators. We investigate this hypothesis at a continental scale (Eurasia) for a medium-sized predator, the red fox Vulpes vulpes, in presence and absence of an apex predator, the Eurasian lynx Lynx lynx. We predicted that in absence of lynx, fox density should be positively associated with open land covers, as these could favour foxes due to high prey availability. Our results showed that fox abundance was independent of land cover in presence of lynx. However, in absence of lynx, fox density was positively but asymptotically related to cropland, while negatively related to grassland. Fox density was highest when cropland constituted approximately 30% of the landscape, likely reflecting an optimal composition of foraging and breeding habitat. Grassland was associated with low productivity, likely reflecting low prey availability. Thus, cropland is favourable for red fox, but only in absence of top-down limitation by lynx. We suggest that there are two ecosystem states in Eurasia, one northern where lynx is present as an apex predator, and one south-eastern where red fox assumes the apex predator position and its abundance is subsidised by anthropogenic land cover.

Place, publisher, year, edition, pages
2015. Vol. 67, 40-48 p.
Keyword [en]
Vulpes vulpes, Lynx lynx, Landscape composition, Ecosystem state, Top-down, Bottom-up
National Category
Biological Sciences
Research subject
Animal Ecology
Identifiers
URN: urn:nbn:se:su:diva-119534DOI: 10.1016/j.actao.2015.04.002ISI: 000358092700006OAI: oai:DiVA.org:su-119534DiVA: diva2:847848
Available from: 2015-08-21 Created: 2015-08-17 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Anthropogenic impact on predator guilds and ecosystem processes: Apex predator extinctions, land use and climate change
Open this publication in new window or tab >>Anthropogenic impact on predator guilds and ecosystem processes: Apex predator extinctions, land use and climate change
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2014. 18 p.
Keyword
Mesopredators, apex predators, top-down, bottom-up, interspecific killing, red fox, Eurasian lynx, grey wolf, wolverine, productivity, winter severity, cropland
National Category
Zoology Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-100720 (URN)978-91-7447-860-0 (ISBN)
Public defence
2014-03-21, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

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.

 

Available from: 2014-02-27 Created: 2014-02-12 Last updated: 2017-06-29Bibliographically approved

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