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Domevscik, Matej, 2018. Resource distribution in disturbed landscapes – the effect of clearcutting on berry abundance and their use by brown bears. Second cycle, A2E. Umeå: SLU, Dept. of Wildlife, Fish and Environmental Studies

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Abstract

To survive winter hibernation, brown bears (Ursus arctos) need to store excess energy during late summer and autumn. Scandinavian brown bears usually have an abundance of berries to feed on, but their distribution varies depending on forest structure and age. Especially on newly cut clearcuts, berry distribution is patchy, but berry production in these patches is exceptionally high. My aim was to model fine-scale temporal variation in berry production in the first years after forest cutting and determine whether bears adjust their space according to forage on clearcuts where berries are abundant. Using plot surveys on clearcuts in south-central Sweden, I collected bilberries (Vaccinium myrtillus) and lingonberries (Vaccinium vitis-idea) from 935 plots and found a nonlinear temporal dynamic of berry presence and abundance following a clearcutting procedure. On young clearcuts, berry production was depressed, it then peaked on clearcuts after around 8 years, and dropped again in later stages of succession. Additionally, bilberry and lingonberry abundance was greater on steeper slopes, with a linear relationship for bilberry and a non-linear relationship for lingonberry, which had a slight decrease at very steep slopes. I found that bears adapted to spatial and temporal dynamics of berry production by selecting for clearcuts of high bilberry presence and especially abundance. This trend was not observed in selection for lingonberry, most likely due to the smaller size of lingonberries and wider availably of bilberries in the year of study. Selection for clearcuts overall was low, with only around 10% of all recorded bear GPS positions being on clearcuts. This is potentially due to perceived hunting risk on open clearcuts and high availability of bilberries also in mature forest. Overall, clearcutting as a method of commercial harvesting of forest landscapes was found to have significant effects on berry production on clearcuts and bears adjusted their space to forage on patches with a high abundance of bilberries.

Main title:Resource distribution in disturbed landscapes – the effect of clearcutting on berry abundance and their use by brown bears
Authors:Domevscik, Matej
Supervisor:Ericsson, Göran and Hertel, Anne Gabriela and Kindberg, Jonas
Examiner:Ecke, Frauke
Series:Examensarbete / SLU, Institutionen för vilt, fisk och miljö
Volume/Sequential designation:2018:8
Year of Publication:2018
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SM003 Management of Fish and Wildlife Populations - Master's Programme 120 HEC
Supervising department:(S) > Dept. of Wildlife, Fish and Environmental Studies
Keywords:bilberry, lingonberry, forest management, ursus arctos, Vaccinium myrtillus, Vaccinium vitis-idaea, resource selection functions, modeling landscape use
URN:NBN:urn:nbn:se:slu:epsilon-s-9683
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-9683
Subjects:Plant ecology
Forestry production
Animal ecology
Language:English
Deposited On:05 Sep 2018 13:30
Metadata Last Modified:06 Sep 2018 06:30

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