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Domingo Gómez, Eva, 2014. Effects of tree retention on cavity-nesting birds in northern Sweden. Second cycle, A2E. Umeå: SLU, Dept. of Wildlife, Fish and Environmental Studies

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Abstract

Tree cavities are of high ecological value because they influence the abundance, diversity, and conservation of many terrestrial animals in forests worldwide. However, due to forest management practices, cavity-users are under a serious threat in many forest ecosystems. With the intention of reducing the impacts of timber harvest, since the mid-1990’s variable amounts of green and dead trees are retained at the clear-cuts in Fennoscandia as a conservation measure supposed to improve conditions for biodiversity. I studied the availability and use of natural tree cavities in retention. It was conducted on a random selection of 100 clear-cuts up to 5 years old within a 20 km radius in the vicinity of Umeå, northern Sweden. A survey of those clear-cuts was performed to study tree retention and to investigate the availability and the potential use of cavities by cavity nesting birds on clear-cuts in boreal Sweden. All cavities and nests found were monitored during two months to study cavity-use. Previous studies have found that the majority of all tree cavities in Europe are natural decay cavities. In my study I found 133 cavity trees that held 241 cavities. Ninety-eight percent of the cavities found were excavated and just 2% were natural cavities produced by decay. This novel finding suggests that also in European boreal
forest the majority of cavities available for secondary cavity nesters are excavated by woodpeckers. Cavity trees were 1.5-2% of the retention trees; Living broadleaved trees, especially aspen, were preferred by birds for breeding. A significantly larger proportion of the
excavated entrance holes were facing a direction from east to south, possibly to maximize the heat from the sun during cold mornings. Estimated cavity tree density ranged from 0.21-0.31 cavity trees ha-1 and cavity density was 0.41 cavities ha-1. All breedings found were in solitary
retention trees showing that successful breedings can take place on clear-cuts in boreal forests.
However, in order to compare cavity densities, their origin and their use by cavity nesting species, a similar study should be performed in old forest. I suggest the conduction of a survey simultaneously in forests and on clear-cuts to provide a basis for comparison between these two
different environments.

Main title:Effects of tree retention on cavity-nesting birds in northern Sweden
Authors:Domingo Gómez, Eva
Supervisor:Roberge, Jean-Michel and Andersson, Jon
Examiner:Edenius, Lars
Series:Examensarbete i ämnet biologi / Sveriges lantbruksuniversitet, Institutionen för vilt, fisk och miljö
Volume/Sequential designation:2014:5
Year of Publication:2014
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SM003 Management of Fish and Wildlife Populations - Master's Programme 120 HEC
Department:(S) > Dept. of Wildlife, Fish and Environmental Studies
Keywords:clear-cuts, tree retention, cavities, biodiversity, primary excavators
URN:NBN:urn:nbn:se:slu:epsilon-s-3139
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-3139
Subjects:Forestry - General aspects
Forest injuries and protection
Animal ecology
Language:English
Deposited On:24 Mar 2014 07:51
Metadata Last Modified:24 Mar 2014 07:51

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