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MILJØFORSK-Miljøforskning for en grønn samfunnsomstilling

Understanding ecosystem functionality, expansion and retreat of species in the Scandinavian mountain tundra under multiple drivers of change

Alternative title: Fjelløkosystemet inn i framtiden: Hvordan vil klimatiske endringer og andre miljøfaktorer påvirke det biologiske mangfoldet?

Awarded: NOK 17.9 mill.

The Fennoscandian mountain range is naturally fragmented, consisting of thousands of large and small islands of alpine tundra areas in forested landscapes. The fragmentation is expected to be magnified, driven by forecasted global warming and land use change. Upward range shifts of the forest is associated with the invasion of boreal species, including a wide range of plant species and mammals like birch and red fox. The forest line is moving upward in Scandinavia. Experimental altering of temperature and herbivory in alpine vegetation show that land use change is the prominent driver of both birch growth and plant community composition compared to climate warming. Monitoring of a large number of long-term plots confirm that the altitudinal position of birch forest lines and tree lines show a large degree of stability if the grazing pressure persist. This contradicts model predictions (which have not included grazing) and general expectations for advancing forest in a warmer climate. We urge the need to include the whole complex of impacts doing scenario modelling. Many species are moving north and upward. We investigate drivers of e.g. the red fox expansion. We find a higher density of generalist predators close to infrastructure and human activity, likely linked to subsidies and surplus food/waist along the roads. Easy access to food resources likely support a higher densities of such species in otherwise marginal alpine landscapes. Attracting boreal species into more marginal alpine areas has cascading negative effects on native, alpine species, acting through increased competition within the predator guild (e.g. increased competition between the invading red fox and native arctic fox) or increased predation on e.g. ground nesting birds. Spatial mark-recapture models based on DNA prove to give good estimates on red fox densities. Through landscape genomics we document how the red foxes move across the Scandinavian landscapes, to map potential risk sof spreading diseases and parasites that could follow i the wake of species expansion/invation. Occurrence of larger carnivores impact the relationship between the two species; red foxes having less negative impact on arctic foxes where wolverines occur. What happens to the species relationship when we give the arctic fox an exclusive access to food? We found that feeding stations are with few exceptions mostly used by arctic foxes, giving the arctic foxes an advantage and access to easily available food resources. Breeding and rearing conditions affect survival later in life and foxes raised in enclosures in the captive breeding station has better survival than wild born foxes, even as adults. We found that cortisol levels in hair/fur are negatively correlated to survival in wild born pups, which indicates that stressors are important factors. Validation experiments confirm that excrements could be used to measure stress in the wild, as a non-invasive methodology. Field data reveal that there are variation in stress among subpopulations of arctic fox, that could relate to competition pressure (density) of red fox, disturbance (tourism) as well as natural prey dynamic. The applied measures to conserve the arctic fox in Scandinavia are indeed successful, leading to a higher genetic diversity and exchange between all subpopulations, and a larger part of the population is involved in the breeding. All leading to increased population viability. We are developing a viability model for the Scandinavian Arctic fox population, including the cyclic nature rodents, and effects of epidemic disease out breaks, which will help to set up conservation goals of species occurring in fragmented landscapes. Advanced genomics is used to explore functional traits for both species, e. g. litter size, fur colorations, behavioural traits, survival, establishment and dispersal. Arctic foxes of the blue colour morph occur to have both higher chances of survival and fitness, than foxes of the white colour morph. We found no relations to climate variables (temperature and snow cover), which suggest that fur colour could be linked to other physical traits being important for survival. An important goal is to develop predictive tools to advice management of the mountain tundra ecosystem. We have built a model predicting the advance and development of the forest line under different scenarios of climate change and grazing regimes. Given expected changes in the pressures that we have explored we will identify where functional mountainous landscapes persist, being large enough for long time survival of native alpine species. Through this approach we will be able to identify areas where and what actions is needed to keep landscape functionality. These scenario tools would be useful for planning and optimizing conservation programs, restoration of landscapes, targeting management actions.

Prosjektet har en utpreget anvendt tilnærming av stor relevans for den praktiske forvaltningen. Å forvalte arealer og arter løsrevet fra det sammenhengende landskapet og økosystemene kan få utilsiktede konsekvenser. ECOFUNC synliggjør noen av disse og understreker behovet for å ha et økosystem-perspektiv i forvaltningen av arter og arealer. Resultatene peker også ut handlingsrommet og dilemmaene vi står ovenfor i praktisk forvaltning. Høyst relevant for bevaring av fjellreven, men også andre høyfjellsarter. Scenariomodeller må romme dette komplekset av påvirkninger for å kunne ha relevans. For hvor består det funksjonelle fjellandskapet og hvor står det i fare for å forsvinne? Realistiske framskrivinger vil peke ut hvor innsatsen bør rettes, med tanke på å opprettholde, eventuelt restaurere, landskap og bestander av enkeltarter. Funksjonelle er en forutsetning for langsiktig overlevelse av artene i fjelløkosystemet, så også for fjellreven.

The Fennoscandian mountain range comprises a series of separate arctic and alpine tundra areas. This natural fragmentation is expected to be magnified following climate mediated forest advance with associated invasion of boreal species. Cumulative effects of climate change, land use changes and management practices will likely have large impacts on both structure and function of the mountain tundra ecosystem; strongly affect biodiversity and the viability of species in these habitats, and the mountain tundra ecosystem's ability to deliver ecosystem services. The proposed project has a tri-trophic ecosystem approach, testing hypotheses about how climate change, land use, and management practices drive species expansion and retreat in the mountain tundra ecosystem. The project will deliver hard data on the relationship between environmental change and functional and structural responses of individuals, populations, and communities of the mountain tundra ecosystem. We will apply an interdisciplinary approach, including observational and experimental methods at large spatial scales, GIS and spatial modelling, landscape genomics, and population viability analyses, providing the basis for a predictive model for the future structure of the mountain tundra ecosystem in Fennoscandia. Our team of dedicated researchers will analyse and synthesize many types of data sets, using new and innovative approaches, which will ensure the production of new and important scientific knowledge. The project is also highly relevant to conservation management. We aim to develop tools that could forecast cumulative impacts from different drivers, providing potential management options showing the outcome of different solutions. Indeed, such tools would be useful for planning and optimising conservation programs, restoration of landscapes, targeting management action, or controlling the spread of diseases.

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MILJØFORSK-Miljøforskning for en grønn samfunnsomstilling