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Larsson, Rebecca, 2015. Restoration of natural disturbances: impact on distribution and performance of dominant ants (Formica spp.) by fire and gap dynamics. Second cycle, A2E. Umeå: SLU, Dept. of Wildlife, Fish and Environmental Studies

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Abstract

Disturbance regimes caused by fire and wind storms used to be common features in the Swedish boreal forests. However, due to an intense forest management, these events have declined rapidly. Little is known about how natural disturbances affect mound-building ants, even though they are important for ecological processes in their role as ecosystem engineers. Effects on ant communities could thus result in further effects on many other species. Wood ants (Formica spp.), a sub-group to mound-building ants, have due to their aggressive behavior and large distribution become the dominant ant species in Swedish forests. The aim of this study was to investigate how restoration of natural disturbances affects the distribution and performance of mound-building ants. Field inventories were conducted during June 2015 in stands subjected to burning and gap creation, with untreated stands used as references. Differences in nest density, ant activity and harvesting of honeydew were measured in the different stand types. My results showed a direct negative affect of fire on nest volume, whilst no effect was found as a result of gap creation. Furthermore, no differences in ant activity among stand types were found, nor did the harvesting rate of honeydew differ. Due to the cold weather for the season, ant activity was in general low, hence resulting in a low honeydew load. My results suggest that ant performance is not affected by the restoration treatments in the short term, but the lack of differences between burned and reference stands might be a result of an adjustment to available resources of the ants. Additionally, the reduced nest volume within burned stands can have further effects on other species interacting with ants. The whole picture of overall effects require a long-term study, and I suggest continued monitoring of Formica spp. ant communities over time.

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Störningsregimer orsakade av bränder och stormar har varit vanligt förekommande i de svenska boreala skogarna, men på grund av det intensiva skogsbruket har dessa störningar minskat kraftigt. Trots stackmyrornas betydelse för ekologiska processer genom sin roll som ”ecosystem engineers”, finns det väldigt lite kunskap om hur myrorna påverkas av naturliga störningar. Effekter på myrsamhällen kan därför resultera i ytterligare effekter på många andra arter. Skogsmyror (Formica spp.), en undergrupp till stackmyror, har genom sitt aggressiva beteende och stora utbredning blivit den dominanta myrgruppen i svenska skogar. Syftet med studien var att undersöka hur restaureringen av naturliga störningar påverkar utbredning och prestationsförmåga hos stackmyror. Fältmätningar genomfördes under juni 2015 i brända och luckhuggna bestånd, med obehandlade bestånd som referensytor. Skillnader i stackdensitet, myraktivitet och insamlandet av honungsdagg mättes i de olika bestånden. Mitt resultat visade en direkt negativ påverkan av brand på stackvolym, medan luckhuggna bestånd inte visade på några skillnader. Vidare hittades inga skillnader i myraktivitet bland bestånden, eller i insamlandet av honungsdagg. Myraktiviteten var generellt låg på grund av det kalla vädret för säsongen, vilket resulterade i en låg mängd insamlad honungsdagg. Mitt resultat tyder på att det inte fanns någon kortsiktig effekt på myrornas prestationsförmåga från restaureringarna, men avsaknaden av skillnader i bränningarna kan tyda på att myrorna anpassat sig till tillgänglig föda. Ytterligare kan den minskade stackvolymen inom de brända ytorna ge vidare effekter på andra arter som integrerar med myror. Helhetsbilden av möjliga effekter från restaureringar kräver en långtidsstudie, och jag föreslår att fortsätta studera myrsamhällen av Formica spp. över tid.

Main title:Restoration of natural disturbances: impact on distribution and performance of dominant ants (Formica spp.) by fire and gap dynamics
Authors:Larsson, Rebecca
Supervisor:Johansson, Therese and Hägglund, Ruaridh
Examiner:Hjälten, Joakim
Series:Examensarbete i ämnet biologi / Sveriges lantbruksuniversitet, Institutionen för vilt, fisk och miljö
Volume/Sequential designation:2015:16
Year of Publication:2015
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SY001 Forest Science - Master's Programme 300 HEC
Department:(S) > Dept. of Wildlife, Fish and Environmental Studies
Keywords:boreal forests, conservation management, honeydew harvesting efficiency, nest density, Sweden
URN:NBN:urn:nbn:se:slu:epsilon-s-4982
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-4982
Subjects:Plant ecology
Forestry - General aspects
Animal ecology
Language:English
Deposited On:23 Nov 2015 16:08
Metadata Last Modified:23 Nov 2015 16:08

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