Cyclic voles and Puumala hantavirus in a changing boreal landscape

Magnus Magnusson

Cyclic voles and Puumala hantavirus in a changing boreal landscape

Bidragets översatta titel: Dynamik av sorkar och Puumala hantavirus i förhållande till intensivt skogsbruk

Magnus Magnusson

Institutionen för vilt, fisk och miljö

Publikation: Avhandling › Doktorsavhandling

2 Nedladdningar

Sammanfattning

Intensivt skogsbruk har påverkat de flesta av världens skogsekosystem och lett till biotopförluster för många specialiserade arter. I norra Sverige har kalhyggesbruket varit den dominerade skogsbruksmetoden sedan 1950-talet. Gamla, flerskiktade skogar har ersatts av unga, enkelskiktade monokulturer. I den här avhandlingen har tre cykliska sorkarter studerats i relation till kalhyggesbruket. Fokus ligger på gråsiding (Myodes rufocanus), men även åkersork (Microtus agrestis) och skogssork (Myodes glareolus) har studerats. Gråsiding minskade markant i täthet och utbredning under 1970- och 1980-talen. Åkersork minskade också medan skogssork, värddjur för Puumala hantavirus (PUUV) som orsakar sorkfeber (nephropathia epidemica) hos människan, inte hade en lika markant nergång som gråsiding och åkersork. Gråsiding föredrog lokalt gamla tallskogar och blockfält. På landskapsnivå var konnektivitet av gammal skog, storlek på fläckar av gammal skog och närhet till blockfält viktigt. Den sammanlagda mängden kalhyggen sedan 1970-talet i olika landskap hade en direkt koppling till gråsidingens minskning. Åkersorkens nergång kunde inte förklaras av kalhyggesbruket men istället verkar vinterförhållanden vara viktiga. Åkersorken återkoloniserade stora delar av undersökningsområdet under 2010-2011, två år som karakteriserades av snörika och kalla vintrar. Den sammanlagda mängden kalhyggen i det omgivande landskapet var också negativt kopplad till förekomst av PUUV-infekterade skogssorkar på våren. Infekterade sorkar överlevde bottenfaser mellan cykler i gamla skogar medan myrar visade sig vara dåliga biotoper för både infekterade och icke infekterade skogssorkar. Sammanfattningsvis konstateras att både den rumsliga och tidsmässiga variationen i täthet och utbredning av gråsiding och PUUV-infekterade skogssorkar påverkas av det intensiva kalhyggesbruket. Landskapsförändringarna orsakade av intensivt kalhyggesbruk har i den boreala skogsregionen skett parallellt med en period av varmare vintrar. Jag föreslår att framtida studier bör fokusera på att undersöka dessa två faktorers relativa påverkan på populationsdynamiken hos PUUV-infekterade skogssorkar, gråsiding och åkersork.

Bidragets översatta titel	Dynamik av sorkar och Puumala hantavirus i förhållande till intensivt skogsbruk
Originalspråk	Engelska
Kvalifikation	Doktor i filosofi
Förlag	Swedish University of Agricultural Sciences
Tryckta ISBN	978-91-576-8206-2
Elektroniska ISBN	978-91-576-8207-9
Status	Publicerad - 2015

Nyckelord

Boreal forest
Clear-cuts
Connectivity
Forestry
Habitat loss
Microtus agrestis
Myodes glareolus
Myodes rufocanus
Puumala Hantavirus
Spatiotemporal changes

SLU-serie

Acta Universitatis Agriculturae Sueciae

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title = "Cyclic voles and Puumala hantavirus in a changing boreal landscape",

abstract = "Land-use change is causing extinction of species globally, while also increasing the risk of disease exposure to humans through augmented interactions with wildlife, when humans live and work in manipulated ecosystems or when animals seek shelter/refuge in man-made infrastructure. Forestry is one such activity, which is continually altering forest structure worldwide, causing habitat loss for many specialized forest species. This study investigates the population ecology of three cyclic vole species, Myodes rufocanus, Myodes glareolus and Microtus agrestis, in relation to intensive forestry in northern Sweden. M. glareolus is also the natural reservoir of Puumala hantavirus (PUUV) which is important from a public health perspective since PUUV causes nephropathia epidemica in humans. M. rufocanus and M. agrestis declined substantially in density and distribution during the 1970-80s while M. glareolus only marginally declined and is still the most common species in the region. The decline of M. rufocanus was related to habitat loss. The cumulated impact from long-term clear-cutting explained local extinctions of M. rufocanus. The species is also dependent on maintained connectivity between old forest and shelter-providing stone fields. In contrast, local extinction of M. agrestis was not related to forestry, suggesting action of another strong driver. M. agrestis re-colonized most of the study area during 2010-2011, two years that were characterised by cold winters and a thick snow cover, suggesting a climatic driver in this case. Occurrence of PUUV infected M. glareolus was negatively related to the impact of long-term clear-cutting in the surrounding landscape. PUUV infected M. glareolus survived during low density periods of the vole cycle in old forests. In summary, the main driver of the decline in density and distribution of M. rufocanus appeared to be intensive forestry. PUUV infection dynamics also appeared to be related to forestry. Since land-use changes and climate changes have coincided in Fennoscandian forests, I suggest that future studies should focus on estimating the relative impact of these two factors on pathogen and vole population dynamics.",

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author = "Magnus Magnusson",

year = "2015",

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isbn = "978-91-576-8206-2",

series = "Acta Universitatis Agriculturae Sueciae",

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N2 - Land-use change is causing extinction of species globally, while also increasing the risk of disease exposure to humans through augmented interactions with wildlife, when humans live and work in manipulated ecosystems or when animals seek shelter/refuge in man-made infrastructure. Forestry is one such activity, which is continually altering forest structure worldwide, causing habitat loss for many specialized forest species. This study investigates the population ecology of three cyclic vole species, Myodes rufocanus, Myodes glareolus and Microtus agrestis, in relation to intensive forestry in northern Sweden. M. glareolus is also the natural reservoir of Puumala hantavirus (PUUV) which is important from a public health perspective since PUUV causes nephropathia epidemica in humans. M. rufocanus and M. agrestis declined substantially in density and distribution during the 1970-80s while M. glareolus only marginally declined and is still the most common species in the region. The decline of M. rufocanus was related to habitat loss. The cumulated impact from long-term clear-cutting explained local extinctions of M. rufocanus. The species is also dependent on maintained connectivity between old forest and shelter-providing stone fields. In contrast, local extinction of M. agrestis was not related to forestry, suggesting action of another strong driver. M. agrestis re-colonized most of the study area during 2010-2011, two years that were characterised by cold winters and a thick snow cover, suggesting a climatic driver in this case. Occurrence of PUUV infected M. glareolus was negatively related to the impact of long-term clear-cutting in the surrounding landscape. PUUV infected M. glareolus survived during low density periods of the vole cycle in old forests. In summary, the main driver of the decline in density and distribution of M. rufocanus appeared to be intensive forestry. PUUV infection dynamics also appeared to be related to forestry. Since land-use changes and climate changes have coincided in Fennoscandian forests, I suggest that future studies should focus on estimating the relative impact of these two factors on pathogen and vole population dynamics.

AB - Land-use change is causing extinction of species globally, while also increasing the risk of disease exposure to humans through augmented interactions with wildlife, when humans live and work in manipulated ecosystems or when animals seek shelter/refuge in man-made infrastructure. Forestry is one such activity, which is continually altering forest structure worldwide, causing habitat loss for many specialized forest species. This study investigates the population ecology of three cyclic vole species, Myodes rufocanus, Myodes glareolus and Microtus agrestis, in relation to intensive forestry in northern Sweden. M. glareolus is also the natural reservoir of Puumala hantavirus (PUUV) which is important from a public health perspective since PUUV causes nephropathia epidemica in humans. M. rufocanus and M. agrestis declined substantially in density and distribution during the 1970-80s while M. glareolus only marginally declined and is still the most common species in the region. The decline of M. rufocanus was related to habitat loss. The cumulated impact from long-term clear-cutting explained local extinctions of M. rufocanus. The species is also dependent on maintained connectivity between old forest and shelter-providing stone fields. In contrast, local extinction of M. agrestis was not related to forestry, suggesting action of another strong driver. M. agrestis re-colonized most of the study area during 2010-2011, two years that were characterised by cold winters and a thick snow cover, suggesting a climatic driver in this case. Occurrence of PUUV infected M. glareolus was negatively related to the impact of long-term clear-cutting in the surrounding landscape. PUUV infected M. glareolus survived during low density periods of the vole cycle in old forests. In summary, the main driver of the decline in density and distribution of M. rufocanus appeared to be intensive forestry. PUUV infection dynamics also appeared to be related to forestry. Since land-use changes and climate changes have coincided in Fennoscandian forests, I suggest that future studies should focus on estimating the relative impact of these two factors on pathogen and vole population dynamics.

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KW - Connectivity

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KW - Puumala Hantavirus

KW - Spatiotemporal changes

KW - Boreal forest

KW - Clear-cuts

KW - Connectivity

KW - Forestry

KW - Habitat loss

KW - Microtus agrestis

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KW - Myodes rufocanus

KW - Puumala Hantavirus

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