| 1. |
- Bergqvist, Göran, et al.
(författare)
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Effects of female body mass and climate on reproduction in northern wild boar
- 2018
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Ingår i: Wildlife Biology. - : Wiley. - 0909-6396 .- 1903-220X.
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian life history strategies depend on climate conditions. Hence, reproductive parameters may vary regionally, and knowledge on such patterns are important for sustainable management. Wild boar research has been biased towards south and central Europe. Here we investigate the effects of mother's carcass mass, season and climate (summer temperature and precipitation as well as January temperature) on pregnancy rate and litter size in 601 free-ranging female wild boar from hemiboreal Sweden, close to the north border of wild boar distribution range in Europe. Pregnancy rate was on average 33.4 +/- 1.94% (mean +/- SE), whereas average litter size of pregnant females was 4.7 +/- 0.12. Pregnancy rate was highest during the seasonal reproduction peak in winter and spring, and both pregnancy rate and litter size increased significantly with increasing female body mass. The probability of a female being pregnant exceeded 50% when carcass mass exceeded 58 kg, equivalent to a live mass of 113 kg, and litter size increased by one for each 16 kg increase in female carcass mass. We found no significant effects of temporal variations in climate, and suggest that such variations were not sufficiently large to affect wild boar reproduction. Alternatively, the reproductive strategy of wild boar may be adjusted to prevailing regional climate conditions. In that case, other life history traits, such as mortality, may be more sensitive to short-term climate fluctuations. Wild boar management needs to take temporal variations in reproduction, as well as in resource availability, into consideration when deciding on prudent management actions.
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| 2. |
- Elmhagen, Bodil, et al.
(författare)
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A boreal invasion in response to climate change? : Range shifts and community effects in the borderland between forest and tundra
- 2015
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44:1, s. 39-50
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Tidskriftsartikel (refereegranskat)abstract
- It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decline or periodically disrupted dynamics in cyclic populations of small and medium-sized mammals and birds. The first warm spell, 1930-1960, stands out as a period of substantial faunal change. However, in addition to climate warming, suggested drivers of change include land use and other anthropogenic factors. We hypothesize all these drivers interacted, primarily favoring southern generalists. Future research should aim to distinguish between effects of climate and land-use change in boreal and tundra ecosystems.
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| 3. |
- Elmhagen, Bodil, et al.
(författare)
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Homage to Hersteinsson and Macdonald : climate warming and resource subsidies cause red fox range expansion and Arctic fox decline
- 2017
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 36:suppl. 1
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Forskningsöversikt (refereegranskat)abstract
- Climate change can have a marked effect on the distribution and abundance of some species, as well as their interspecific interactions. In 1992, before ecological effects of anthropogenic climate change had developed into a topical research field, Hersteinsson and Macdonald published a seminal paper hypothesizing that the northern distribution limit of the red fox (Vulpes vulpes) is determined by food availability and ultimately climate, while the southern distribution limit of the Arctic fox (Vulpes lagopus) is determined by interspecific competition with the larger red fox. This hypothesis has inspired extensive research in several parts of the circumpolar distribution range of the Arctic fox. Over the past 25 years, it was shown that red foxes can exclude Arctic foxes from dens, space and food resources, and that red foxes kill and sometimes consume Arctic foxes. When the red fox increases to ecologically effective densities, it can cause Arctic fox decline, extirpation and range contraction, while conservation actions involving red fox culling can lead to Arctic fox recovery. Red fox advance in productive tundra, concurrent with Arctic fox retreat from this habitat, support the original hypothesis that climate warming will alter the geographical ranges of the species. However, recent studies show that anthropogenic subsidies also drive red fox advance, allowing red fox establishment north of its climate-imposed distribution limit. We conclude that synergies between anthropogenic subsidies and climate warming will speed up Arctic ecosystem change, allowing mobile species to establish and thrive in human-provided refugia, with potential spill-over effects in surrounding ecosystems.
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| 4. |
- Elmhagen, Bodil, et al.
(författare)
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Implications of climate and land-use change for landscape processes, biodiversity, ecosystem services, and governance
- 2015
-
Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44, s. s1-S5
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Tidskriftsartikel (refereegranskat)abstract
- This introduction to the Special Issue summarizes the results of 14 scientific articles from the interdisciplinary research program Ekoklim at Stockholm University, Sweden. In this program, we investigate effects of changing climate and land use on landscape processes, biodiversity, and ecosystem services, and analyze issues related to adaptive governance in the face of climate and land-use change. We not only have a research focus on the 22 650 km(2) Norrstrom catchment surrounding lake Malaren in south-central Sweden, but we also conduct research in other Swedish regions. The articles presented here show complex interactions between multiple drivers of change, as well as feedback processes at different spatiotemporal scales. Thus, the Ekoklim program highlights and deals with issues relevant for the future challenges society will face when land-use change interacts with climate change.
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| 5. |
- Elmhagen, Bodil, et al.
(författare)
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Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services
- 2015
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Ingår i: Ecology and Society. - 1708-3087. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6 degrees C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.
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| 6. |
- Elmhagen, Bodil, et al.
(författare)
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Åtgärdsprogram för fjällräv, 2017–2021 : (Vulpes lagopus)
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fjällräven är klassificerad som starkt hotad i Sverige och akut hotad i Norge. På 1800-talet var det en vanligt förekommande art, men till följd av intensivt jakttryck reducerades populationen kraftigt i slutet av 1800-talet. Fjällräven fridlystes 1928 i Sverige och 1930 i Norge. Trots skydd har populationen inte återhämtat sig. Detta beror på ett flertal samverkande faktorer, framförallt låg populationsstorlek, ökad konkurrens från rödrävar som expanderar in i fjällvärlden, samt uteblivna eller mer oregelbundna lämmeltoppar som leder till födobrist. Dessutom har inavel och inavelsdepression med ökad dödlighet och minskad reproduktion dokumenterats i vissa delbestånd. Sjukdomar och parasiter utgör ett ytterligare hot mot de små delpopulationernas fortlevnad. Störningar från mänskliga aktiviteter kan utgöra ytterligare bidragande faktorer.År 2015 fanns omkring 240 reproducerande vuxna fjällrävar i Sverige och Norge, vilket utgör ett mått på beståndets minimala storlek. Inom EU är fjällräven en prioriterad art enligt habitatdirektivet, i Sverige är fjällräven fridlyst enligt artskyddsförordningen, och i Norge är fjällräven skyddad med ”fjällrävförskriften” enligt naturmangfoldloven.Åtgärder för att rädda fjällräven genomfördes i Sverige och Finland under 1998–2002 genom EU-Life Nature projektet SEFALO. Projektet fortsatte i en andra fas, SEFALO+ (2003–2008) som även involverade Norge. Båda projekten inkluderade åtgärder som stödutfodring, rödrävsjakt och inventeringar. I Norge startade flera åtgärder 2004 på uppdrag av Miljødirektoratet (tidigare Direktoratet for naturforvaltning). Sedan dess har en kombination av åtgärder genomförts i olika delbestånd: avel och utsättning av valpar, stödutfodring, samt kontroll av rödrävsbestånden. Avelsprojekt för fjällräv startade 2005 och de första valparna sattes ut 2006. Inom EU-Interregprojektet Felles Fjellrev (2010–2013) genomfördes utvidgade åtgärder i Jämtlands län samt Nord- och Sør-Trøndelag, med riktade åtgärder i mindre fjällområden mellan de fyra större delbestånden av fjällräv.För att fjällrävsstammen ska återuppnå en gynnsam bevarandestatus bör bevarandeåtgärderna fortsätta inom ramen för det svensk-norska åtgärdsprogrammet. Den långsiktiga visionen är att skapa en stabil och livskraftig stam med gynnsam bevarandestatus utan behov av ytterligare åtgärder. Det är emellertid långt tills denna vision uppnås och i detta program definieras konkreta målsättningar på lång (2035) och kort (2021) sikt. I detta program föreslås fortsatt genomförande av centrala åtgärder i form av stödutfodring och rödrävskontroll. Dessutom ska orsakerna till rödrävens ökade förekomst på fjället hanteras genom åtgärder mot de faktorer som gynnar expansionen. Avel och utsättning från det norska avelsprojektet, alternativt translokering av rävar mellan delpopulationerna, föreslås som åtgärd för att förstärka små populationer, etablera fjällrävar i mellanområden samt minska graden av inavel. Populationernas hälsostatus bör övervakas och vid ett utbrott ska behandling sättas in. Riktade informationskampanjer ska utformas för att minska konflikt och störning med människan.De åtgärder som förutsätts finansieras av Naturvårdsverket och Miljødirektoratet för genomförande av åtgärdsprogram för hotade arter beräknas totalt uppgå till 15, 1 miljoner kronor respektive 47,6 miljoner kronor under programmets giltighetsperiod 2017–2021.
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| 7. |
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| 8. |
- Haage, Marianne, et al.
(författare)
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An experimental approach to the formation of diet preferences and individual specialisation in European mink
- 2017
-
Ingår i: European Journal of Wildlife Research. - : Springer Science and Business Media LLC. - 1612-4642 .- 1439-0574. ; 63:2, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Individual dietary specialisation can occur within populations even when average diets suggest that the population has a generalist feeding strategy. Individual specialisation may impact fitness and has been related to demographic traits, ecological opportunity, competition, learning and animal personality. However, the causation and formation of individual specialisation are not fully understood. Experiments on animals raised in controlled environments provide an opportunity to examine dietary preferences and learning largely independent from variation in lifetime experiences and ecological opportunity. Here, we use a feeding experiment to examine individual specialisation and learning in captive bred European mink (Mustela lutreola) in an Estonian conservation programme. In a series of cafeteria experiments, animals could choose between one familiar food item (Baltic herring Clupea harengus membras) and two initially novel ones (noble crayfish Astacus astacus and house mouse Mus musculus). In general, mice were rarely eaten whilst crayfish consumption increased over time and fish decreased. At the individual level, there was a mix of generalists and crayfish or fish specialists, and the individuals differed in learning time in relation to novel prey. Our results indicate that individual variation in innate preferences and learning both contributes to individual diet specialisation. The differences in learning indicate individual variation in behavioural plasticity, which in turn can be related to personality. This could be of concern in conservation, as personality has been shown to affect survival in translocations.
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| 9. |
- Haage, Marianne, 1985-
(författare)
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Conservation, personality and ecology of the European mink (Mustela lutreola)
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Loss of biodiversity is a growing problem and hence conservation of species is becoming increasingly important. In this dissertation conservation issues related to the critically endangered European mink (Mustela lutreola) are examined in situ (in the wild) and ex situ (in captivity) on both an individual and community level. It also contains fundamental research as conservation contexts often allow for conclusions beyond applied biology. Individual behavioural differences, e.g. personality, can impact fitness and are hence relevant for conservation. Paper I thus experimentally explores the structure, expression and plasticity of personality in captive European minks. Thereafter paper II investigates if personality affects survival of reintroduced captive-bred animals and if spatiotemporal conditions affects the relationship between personality and survival. Paper III experimentally explores individual dietary specialism and learning in relation to novel prey as this could also impact survival. One of the main threats to the European mink is displacement by the invasive American mink (Neovison vison) wherefore management of American mink is important for European mink conservation. Paper IV hence analyses survey data to study whether native otters and red foxes can suppress American mink populations in north-eastern Europe. In the results three personality trait domains were identified in the European mink: boldness, exploration and sociability. The domains were repeatable but plastic between the non-breeding and breeding season. Reintroduced personality-tested animals survived longer if they were bolder but the effect of exploration was either positive or negative depending on spatiotemporal conditions. This is not only interesting for conservation but provides new insights on how individual behavioural differences could be maintained over evolutionary time. Whilst exploration is likely to be maintained by fluctuating selection pressures, the mechanism seem to vary with domain. The feeding experiments revealed diet choices similar to those found in wild individuals as there were both generalists and different types of specialists. Still, individuals differed in learning time towards novel but natural prey, suggesting that reintroduced animals might differ in their ability to find food after release. This could affect survival also and be related to personality. Survey data revealed that American mink abundances were suppressed by those of red foxes. Previous studies show that foxes are suppressed by lynx, and the abundance pattern of mink in relation to red fox found here indicate the existence of a predator cascade as mink were most abundant where lynx were abundant and vice versa. In several regions in the study area population dynamics indicated either exploitation or interference competition as probable mechanisms whereby foxes suppress minks. However, in many regions there were no relationships between dynamics. This could be due to that exploitation and interference competition might occur simultaneously and thus cancel each other out in the dynamics. Overall this thesis shows the importance of considering individual traits in conservation efforts, and also provides knowledge on the structure, plasticity and evolution of personality. As American mink was suppressed by foxes, management efforts might be most beneficial for species impacted by the mink if they to a larger extent are undertaken in areas with low fox abundances.
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| 10. |
- Haage, Marianne, et al.
(författare)
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The influence of spatiotemporal conditions and personality on survival in reintroductions-evolutionary implications
- 2017
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 183:1, s. 45-56
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Tidskriftsartikel (refereegranskat)abstract
- Personality exists in non-human animals and can impact fitness. There is, however, a shortage of empirical studies in certain areas within the field, and fundamental evolutionary theory on personality remains largely untested. For example, little is known on how variation in personality is maintained over evolutionary time. Theory suggests that fluctuating selection pressures due to spatiotemporal variation in conditions, e.g. food availability, is a possible mechanism and a few studies have shown that the success of different personality types varies with spatiotemporal conditions. However, it remains unknown whether different mechanisms can maintain personality within a species. Here we use a reintroduction programme for the critically endangered European mink (Mustela lutreola) to test whether multiple personality trait domains (boldness, exploration and sociability) affected survival in two different years and islands. This was done through pre-release personality tests and post-release radio-tracking monitoring. Survival was positively correlated with boldness, whereas the relationship with exploration was either negative or positive depending on year/island. The results show a complex relationship between personality and survival and suggest that exploration can be maintained over evolutionary time via spatiotemporal variation in conditions. However, in contrast to exploration, boldness did not vary spatiotemporally and sociability had no impact on survival. This indicates that different personality trait domains might be maintained by different mechanisms. To date, personality has been studied primarily within behavioural sciences, but through empirical findings we highlight the importance of personality also in ecology and conservation biology.
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| 11. |
- Kuijper, D. P. J., et al.
(författare)
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Paws without claws? Ecological effects of large carnivores in anthropogenic landscapes
- 2016
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 283:1841
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Tidskriftsartikel (refereegranskat)abstract
- Large carnivores are frequently presented as saviours of biodiversity and ecosystem functioning through their creation of trophic cascades, an idea largely based on studies coming primarily out of relatively natural landscapes. However, in large parts of the world, particularly in Europe, large carnivores live in and are returning to strongly human-modified ecosystems. At present, we lack a coherent framework to predict the effects of large carnivores in these anthropogenic landscapes. We review how human actions influence the ecological roles of large carnivores by affecting their density or behaviour or those of mesopredators or prey species. We argue that the potential for density-mediated trophic cascades in anthropogenic landscapes is limited to unproductive areas where even low carnivore numbers may impact prey densities or to the limited parts of the landscape where carnivores are allowed to reach ecologically functional densities. The potential for behaviourally mediated trophic cascades may be larger and more widespread, because even low carnivore densities affect prey behaviour. We conclude that predator-prey interactions in anthropogenic landscapes will be highly context-dependent and human actions will often attenuate the ecological effects of large carnivores. We highlight the knowledge gaps and outline a new research avenue to study the role of carnivores in anthropogenic landscapes.
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| 12. |
- Larm, Malin, et al.
(författare)
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The role of wildlife tourism in conservation of endangered species : Implications of safari tourism for conservation of the Arctic fox in Sweden
- 2018
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Ingår i: Human Dimensions of Wildlife. - : Informa UK Limited. - 1087-1209 .- 1533-158X. ; 23:3, s. 257-272
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Tidskriftsartikel (refereegranskat)abstract
- There are both positive and negative impacts on wildlife associated with wildlife tourism. In Sweden, the endangered Arctic fox is subject to a growing tourist interest. In the Helags mountain region there are guided Arctic fox safari tours that provide visitors with information about the Arctic fox. A survey of five separate groups of visitors in the region revealed that knowledge about the status of Arctic foxes and awareness of the behavioral guidelines for Arctic fox encounters improved after participation in a safari tour and with increasing Arctic fox interaction. We propose a schematic model summarizing the diverse ways in which wildlife tourism affects wildlife and their relative importance for conservation. The Arctic fox population in Sweden is small and sensitive to disturbance, but the positive impacts of Arctic fox tourism seem to compensate for the negative and contribute to their conservation under the current level of tourism pressure.
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| 13. |
- Le Vaillant, Maryline, et al.
(författare)
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Spatial distribution in Norwegian lemming Lemmus lemmus in relation to the phase of the cycle
- 2018
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Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 41:7, s. 1391-1403
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Tidskriftsartikel (refereegranskat)abstract
- Competition between individuals of the same or different species affects spatial distribution of organisms at any given time. Consequently, a species geographical distribution is related to population dynamics through density-dependent processes. Small Arctic rodents are important prey species in many Arctic ecosystems. They commonly show large cyclic fluctuations in abundance offering a potential to investigate how landscape characteristics relates to density-dependent habitat selection. Based on long-term summer trapping data of the Norwegian lemming (Lemmus lemmus) in the Scandinavian Mountain tundra, we applied species distribution modeling to test if the effect of environmental variables on lemming distribution changed in relation to the lemming cycle. Lemmings were less habitat specific during the peak phase, as their distribution was only related to primary productivity. During the increase phase, however, lemming distribution was, in addition, associated with landscape characteristics such as hilly terrain and slopes that are less likely to get flooded. Lemming habitat use varied during the cycle, suggesting density-dependent changes in habitat selection that could be explained by intraspecific competition. We believe that the distribution patterns observed during the increase phase show a stronger ecological signal for habitat preference and that the less specific habitat use during the peak phase is a result of lemmings grazing themselves out of the best habitat as the population grows. Future research on lemming winter distribution would make it possible to investigate the year around strategies of habitat selection in lemmings and a better understanding of a fundamental actor in many Arctic ecosystems.
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| 14. |
- Pasanen-Mortensen, Marianne, et al.
(författare)
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Land cover effects on mesopredator abundance in the presence and absence of apex predators
- 2015
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Ingår i: Acta Oecologica. - : Elsevier BV. - 1146-609X .- 1873-6238. ; 67, s. 40-48
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Tidskriftsartikel (refereegranskat)abstract
- Trophic downgrading due to loss of apex consumers has been detected in many ecosystems. Loss of larger predators implies that medium-sized mesopredators rise to the status of apex predators which are limited bottom-up rather than top-down. Hence the density of medium-sized predators should be more strongly related to land cover in absence of larger predators. We investigate this hypothesis at a continental scale (Eurasia) for a medium-sized predator, the red fox Vulpes vulpes, in presence and absence of an apex predator, the Eurasian lynx Lynx lynx. We predicted that in absence of lynx, fox density should be positively associated with open land covers, as these could favour foxes due to high prey availability. Our results showed that fox abundance was independent of land cover in presence of lynx. However, in absence of lynx, fox density was positively but asymptotically related to cropland, while negatively related to grassland. Fox density was highest when cropland constituted approximately 30% of the landscape, likely reflecting an optimal composition of foraging and breeding habitat. Grassland was associated with low productivity, likely reflecting low prey availability. Thus, cropland is favourable for red fox, but only in absence of top-down limitation by lynx. We suggest that there are two ecosystem states in Eurasia, one northern where lynx is present as an apex predator, and one south-eastern where red fox assumes the apex predator position and its abundance is subsidised by anthropogenic land cover.
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| 15. |
- Pasanen-Mortensen, Marianne, et al.
(författare)
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The changing contribution of top-down and bottom-up limitation of mesopredators during 220 years of land use and climate change
- 2017
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 86:3, s. 566-576
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Tidskriftsartikel (refereegranskat)abstract
- Apex predators may buffer bottom-up driven ecosystem change, as top-down suppression may dampen herbivore and mesopredator responses to increased resource availability. However, theory suggests that for this buffering capacity to be realized, the equilibrium abundance of apex predators must increase. This raises the question: will apex predators maintain herbivore/mesopredator limitation, if bottom-up change relaxes resource constraints? Here, we explore changes in mesopredator (red fox Vulpes vulpes) abundance over 220years in response to eradication and recovery of an apex predator (Eurasian lynx Lynx lynx), and changes in land use and climate which are linked to resource availability. A three-step approach was used. First, recent data from Finland and Sweden were modelled to estimate linear effects of lynx density, land use and winter temperature on fox density. Second, lynx density, land use and winter temperature was estimated in a 22650km(2) focal area in boreal and boreo-nemoral Sweden in the years 1830, 1920, 2010 and 2050. Third, the models and estimates were used to project historic and future fox densities in the focal area. Projected fox density was lowest in 1830 when lynx density was high, winters cold and the proportion of cropland low. Fox density peaked in 1920 due to lynx eradication, a mesopredator release boosted by favourable bottom-up changes - milder winters and cropland expansion. By 2010, lynx recolonization had reduced fox density, but it remained higher than in 1830, partly due to the bottom-up changes. Comparing 1830 to 2010, the contribution of top-down limitation decreased, while environment enrichment relaxed bottom-up limitation. Future scenarios indicated that by 2050, lynx density would have to increase by 79% to compensate for a projected climate-driven increase in fox density. We highlight that although top-down limitation in theory can buffer bottom-up change, this requires compensatory changes in apex predator abundance. Hence apex predator recolonization/recovery to historical levels would not be sufficient to compensate for widespread changes in climate and land use, which have relaxed the resource constraints for many herbivores and mesopredators. Variation in bottom-up conditions may also contribute to context dependence in apex predator effects.
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| 16. |
- Stoessel, Marianne, et al.
(författare)
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The fluctuating world of a tundra predator guild : bottom‐up constraints overrule top‐down species interactions in winter
- 2019
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 42:3, s. 488-499
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Tidskriftsartikel (refereegranskat)abstract
- Global warming is predicted to change ecosystem functioning and structure in Arctic ecosystems by strengthening top‐down species interactions, i.e. predation pressure on small herbivores and interference between predators. Yet, previous research is biased towards the summer season. Due to greater abiotic constraints, Arctic ecosystem characteristics might be more pronounced in winter. Here we test the hypothesis that top‐down species interactions prevail over bottom‐up effects in Scandinavian mountain tundra (Northern Sweden) where effects of climate warming have been observed and top‐down interactions are expected to strengthen. But we test this ‘a priori’ hypothesis in winter and throughout the 3–4 yr rodent cycle, which imposes additional pulsed resource constraints. We used snowtracking data recorded in 12 winters (2004–2015) to analyse the spatial patterns of a tundra predator guild (arctic fox Vulpes lagopus, red fox Vulpes vulpes, wolverine Gulo gulo) and small prey (ptarmigan, Lagopus spp). The a priori top‐down hypothesis was then tested through structural equation modelling, for each phase of the rodent cycle. There was weak support for this hypothesis, with top‐down effects only discerned on arctic fox (weakly, by wolverine) and ptarmigan (by arctic fox) at intermediate and high rodent availability respectively. Overall, bottom‐up constraints appeared more influential on the winter community structure. Cold specialist predators (arctic fox and wolverine) showed variable landscape associations, while the boreal predator (red fox) appeared strongly dependent on productive habitats and ptarmigan abundance. Thus, we suggest that the unpredictability of food resources determines the winter ecology of the cold specialist predators, while the boreal predator relies on resource‐rich habitats. The constraints imposed by winters and temporary resource lows should therefore counteract productivity‐driven ecosystem change and have a stabilising effect on community structure. Hence, the interplay between summer and winter conditions should determine the rate of Arctic ecosystem change in the context of global warming.
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| 17. |
- Widemo, Fredrik, et al.
(författare)
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Viltets ekosystemtjänster : En kunskapssammanställning till stöd för värdering och förvaltning
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det finns en mängd mer eller mindre strikta definitioner och indelningar av ekosystemtjänster. Vi föredrar att inte göra någon åtskillnad mellan processer som levererar nyttigheter och de nyttigheter som produceras. I rapporten ser vi därmed exempelvis viltkött, eller glädjen över att se en björn, som ekosystemtjänster, inte som nyttigheter som är ett resultat av ekosystemtjänster. Det stora värdet med konceptet ekosystemtjänster ligger i att olika värden identifieras, samt insikten att olika tjänster ofta begränsar varandra. Det går följaktligen inte att maximera alla tjänster, utan förvaltning av naturresurser ur ett ekosystemtjänstperspektiv bygger på accepterade avvägningar mellan identifierade tjänster. Människan är en del av ekosystemen. Leveransen av viltets ekosystemtjänster påverkas i stor utsträckning av landskapet och därmed av mänsklig markanvändning. För att värdera och förvalta viltets ekosystemtjänster är det nödvändigt att känna till hur viltet påverkar landskapet, hur landskapet och markanvändningen påverkar viltet samt hur olika avvägningar ger återkopplingar till ekosystemen. Ekosystemtjänster samskapas genom komplicerade samspel mellan biologisk mångfald och ekologiska processer å ena sidan och människans sociala system, aktiviteter och investeringar å andra sidan. Ofta beror problem med att omsätta ekosystemtjänstkonceptet i praktisk förvaltning på svårigheter att samtidigt hantera försörjande (materiella) och kulturella (immateriella) tjänster, där de senare ofta inte kan värdesättas kvantitativt. Det gör det svårt att finna goda avvägningar mellan försörjande och kulturella tjänster. Det totala värdet av de kulturella tjänsterna i landskapet överstiger ofta det totala värdet av alla de försörjande tjänsterna. Det gäller även värdet av viltets ekosystemtjänster. Olika intressegrupper, och individer inom intressegrupper, värderar ofta samma ekosystemtjänst olika. Förvaltning av naturresurser ur ett ekosystemtjänstperspektiv kräver dialog mellan aktörer om identifiering, värdering och förvaltning av ekosystemtjänster. Strikta, exkluderande definitioner och fokus på kvantitativ, monetär värdering försvårar ofta processen och tillämpningen; vi förordar inkluderande förhållningssätt, även om det försvårar eller omöjliggör monetär värdering och ekonomiska kostnads-nyttoanalyser.Stammarna av klövvilt, storfåglar (gäss, trana och sångsvan) och stora rovdjur har vuxit starkt under de senaste hundra åren till följd av framgångsrik förvaltning. Dagens starka stammar levererar stora ekosystemtjänster direkt och indirekt (Figur 1), men kan även leverera ‑otjänster. Detta skapar konflikter och behov av avvägningar mellan olika intressen inom samförvaltningen av vilt, andra naturresurser och upplevelsevärden. Betande klövvilt och betande storfåglar har viktiga strukturerande effekter på vegetationen. Låga och medelhöga betestryck har generellt positiva effekter på den biologiska mångfalden, särskilt om betestrycket varierar i tid och rum på landskapsnivå. Avsaknad av bete kan precis som höga betestryck ha negativa effekter på den biologiska mångfalden, genom att det ger minskad variation av livsmiljöer. De stora rovdjuren levererar stora kulturella ekosystemtjänster, men har ofta begränsad populationsreglerande effekt på klövvilt i Sverige eftersom klövviltsstammarna begränsas genom jakt. Jägarna kompenserar dessutom för de stora rovdjurens predation genom minskat jaktuttag. Det gör att rovdjuren kan begränsa ekosystemtjänsterna från jakt på klövvilt mer eller mindre kraftigt, men samtidigt har begränsad inverkan på klövviltstammarnas storlek. Det går inte att jämföra de stora rovdjurens ekologiska roll utan jakt, exempelvis i nationalparker, med effekter i normala svenska produktionslandskap.Kvantitativa värderingar av psykosociala effekter av rovdjur saknas i stor utsträckning; innan både positiva och negativa effekter studerats är det svårt eller omöjligt att finna goda avvägningar. Generellt saknas kvantitativa data för många kulturella ekosystemtjänster från vilt, som exempelvis upplevelsevärden av att se vilt för allmänhet och turister. Skador från vilt är ofta ojämnt fördelade i tid och rum. Genomsnittliga nationella och regionala skadenivåer kan därmed vara vilseledande när det gäller vilka utmaningar enskilda brukare och förvaltningen ställs inför. Viltförvaltningen måste därmed utgå från lokala förhållanden för att åtgärder ska kunna skräddarsys efter upplevda behov och bidra till god måluppfyllnad, exempelvis när det gäller att hantera omfattande, men lokala, skador. Lokal delaktighet ökar samtidigt sannolikheten att nå acceptans för avvägningar mellan konkurrerande ekosystemtjänster. Nödvändiga data för att göra en komplett samhällsekonomisk analys av ekosystemtjänster och -otjänster från vilt saknas idag. Vi har medvetet avstått från att jämföra de ekonomiska värden som trots allt finns i en kostnadsnyttoanalys, eftersom en sådan inte skulle inkludera alla relevanta ekosystemtjänster. Eventuella avvägningar baserade på en sådan analys skulle därmed inte inkludera alla tjänster eller intressen, och skulle därmed riskera att öka snarare än minska mängden konflikter om förvaltningsbeslut och -åtgärder baseras på ofullständiga beslutsunderlag. Jaktlagen uttrycker sedan revideringen 1987 ett gemensamt ansvar mellan jakträttshavare och markägare att förvalta viltet utifrån enskilda och allmänna intressen. Lagstiftningen bygger på grundprinciperna inom ekosystemtjänstkonceptet, och har bidragit till att det idag finns formaliserade arenor för att finna avvägningar mellan ekosystemtjänster på olika nivåer. Viltförvaltningen ligger därmed långt framme i omställningen mot att förvalta naturresurser utifrån ett ekosystemtjänstperspektiv, i enlighet med fattade riksdagsbeslut. Här finns generella lärdomar att dra för den övriga förvaltningen. För att nå längre mot en adaptiv förvaltning av vilt med accepterade avvägningar mellan olika ekosystemtjänster och -otjänster krävs ytterligare fokus på underifrånperspektiv, delaktighet och breda analyser. Det är nödvändigt att viltets reglerande ekosystemtjänster, kulturella ekosystemtjänster respektive strukturerande effekter på ekosystemen inkluderas i beslutsunderlagen i större utsträckning än idag. För vilt som rör sig över stora områden måste lokal förvaltning kombineras med regional, nationell och internationell samverkan.
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