| 1. |
- Elmendorf, Sarah C., et al.
(författare)
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Global assessment of experimental climate warming on tundra vegetation : heterogeneity over space and time
- 2012
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 15:2, s. 164-175
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Forskningsöversikt (refereegranskat)abstract
- Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation and associated ecosystem consequences have the potential to be much greater than we have observed to date.
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| 2. |
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| 3. |
- Fosaa, Anna Maria
(författare)
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Biodiversity patterns of vascular plant species in mountain vegetation in the Faroe Islands
- 2004
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Ingår i: Diversity and Distributions. - : Wiley. - 1366-9516. ; 10:3, s. 217-223
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Tidskriftsartikel (refereegranskat)abstract
- Biodiversity patterns of vascular plant species were studied along altitudinal gradients in the Faroe Islands. Plants were sampled from five different mountains (150-856 m a.s.l.) at 50 m altitudinal intervals. Included in the study were 107 vascular plant species. In order to compare only altitudes with the same number of plots, three different analyses were carried out. One analysis included five mountains from 250 to 750 m a.s.l., one had three mountains from 150 to 750 m a.s.l., and the last one had two mountains from 750 to 850 m a.s.l. The patterns of biodiversity were evaluated on the basis of species richness as the total number of species at each altitudinal interval, as species turnover between altitudes and in relation to the Shannon-Wiener index. Similar patterns were found for species richness in the three analyses, although richness was higher along the whole transect when five mountains were included. For the Shannon-Wiener index, only small differences were found among the three analyses. A maximum was seen at 250 m a.s.l. and again at 500 m a.s.l. both in richness and in the Shannon-Wiener index. Maximum species turnover was found at mid-altitudes. Total vegetation cover followed the same pattern as richness. In addition to climate, the altitudinal variation of biodiversity may be affected by grazing.
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| 4. |
- Fosaa, Anna Maria
(författare)
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Mountain vegetation in the Faroe Islands in a climate change perspective
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is a study of the mountain vegetation in the Faroe Islands based on five altitudinal transects sampled during the period 1999-2001. The vegetation was studied on the basis of plant communities, life-forms and biodiversity of vascular plant species and is discussed in a climate change perspective. The boundary between arctic and temperate vegetation is established and the tolerance of character species was tested according to different temperature parameters. The aim has been to assess how the vegetation might be affected by climate change. Three significantly different altitudinal vegetation zones were defined, a temperate zone (upper limit at 200 m a.s.l.), a low alpine zone (200-400 m a.s.l.) and an alpine zone (above 400 m a.s.l). The shift in vegetation zones is also seen in the change of biodiversity of vascular plant species where two maxima in biodiversity are found, one at 250 m a.s.l, the other at 500 m a.s.l. These maxima might indicate transition areas between the zones, more or less overlaps with the low alpine vegetation zone. The study on Raunkiær’s life-forms also showed that the ratio between hemicryptophytes/chamaephytes was at its maximum in this zone. In earlier studies, the boundary between the low alpine and the alpine zone is found at a higher altitude. This could indicate that a lowering in the alpine zone has occurred within the last fifty years as a result of a cooling by about 0.25°C. The responses of changing summer and winter (soil) temperature on twelve plant species, in a cooling or warming scenario, shows that the species most threatened by a warming scenario are those that are found with a limited distribution restricted to the uppermost parts of the mountains, especially Salix herbacea, Racomitrium fasciculare, and Bistorta vivipara. For species found at lower altitudes, the effect will mainly be a general upward migration. The most sensitive species are those with a low tolerance, especially Calluna vulgaris, and also Empetrum nigrum, and Nardus stricta. If the climate in the Faroe Islands should become colder, the most vulnerable species are those at low altitudes, especially Vaccinium myrtillus and Galium saxatilis. Species like Empetrum nigrum, Nardus stricta, and Calluna vulgaris may also be threatened. In any case, these species can be expected to migrate downwards.
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| 5. |
- Fosaa, Anna Maria, et al.
(författare)
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Potential effects of climate change on plant species in the Faroe Islands
- 2004
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Ingår i: Global Ecology and Biogeography Letters. - 0960-7447. ; 13:5, s. 427-437
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Tidskriftsartikel (refereegranskat)abstract
- Aim To identify the effect of climate change on selected plant species representative of the main vegetation types in the Faroe Islands. Due to a possible weakening of the North Atlantic Current, it is difficult to predict whether the climate in the Faroe Islands will be warmer or colder as a result of global warming. Therefore, two scenarios are proposed. The first scenario assumes an increase in summer and winter temperature of 2 degreesC, and the second a decrease in summer and winter temperature of 2 degreesC. Location Temperate, low alpine and alpine areas in the northern and central part of the Faroe Islands. Methods The responses of 12 different plant species in the Faroe Islands were tested against measured soil temperature, expressed as T-min, T-max, snow cover and growing degree days (GDD), using generalised linear modelling (GLM). Results The tolerance to changes in winter soil temperature (0.3-0.8 degreesC) was found to be lower than the tolerance to changing summer soil temperature (0.7-1.0 degreesC), and in both cases lower than the predicted climate changes. Conclusions The species most affected by a warming scenario are those that are found with a limited distribution restricted to the uppermost parts of the mountains, especially Salix herbacea, Racomitrium fasciculare, and Bistorta vivipara. For other species, the effect will mainly be a general upward migration. The most vulnerable species are those with a low tolerance, especially Calluna vulgaris, and also Empetrum nigrum, and Nardus stricta. If the climate in the Faroe Islands should become colder, the most vulnerable species are those at low altitudes. A significantly lower temperature would be expected to produce a serious reduction in the extent of Vaccinium myrtillus and Galium saxatilis. Species like Empetrum nigrum, Nardus stricta, and Calluna vulgaris may also be vulnerable. In any case, these species can be expected to migrate downwards.
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| 6. |
- Hagen, Dagmar, et al.
(författare)
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Ecological and social dimensions of ecosystem restoration in the nordic countries
- 2013
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Ingår i: Ecology and Society. - 1708-3087. ; 18:4, s. 34-
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Tidskriftsartikel (refereegranskat)abstract
- An international overview of the extent and type of ecological restoration can offer new perspectives for understanding, planning, and implementation. The Nordic countries, with a great range of natural conditions but historically similar social and political structures, provide an opportunity to compare restoration approaches and efforts across borders. The aim of this study was to explore variation in ecological restoration using the Nordic countries as an example. We used recent national assessments and expert evaluations of ecological restoration. Restoration efforts differed among countries: forest and peatland restoration was most common in Finland, freshwater restoration was most common in Sweden, restoration of natural heathlands and grasslands was most common in Iceland, restoration of natural and semi-cultural heathlands was most common in Norway, and restoration of cultural ecosystems, mainly abandoned agricultural land, was most common in Denmark. Ecological restoration currently does not occur on the Faroe Islands. Economic incentives influence ecological restoration and depend on laws and policies in each country. Our analyses suggest that habitat types determine the methods of ecological restoration, whereas socio-economic drivers are more important for the decisions concerning the timing and location of restoration. To improve the understanding, planning, and implementation of ecological restoration, we advocate increased cooperation and knowledge sharing across disciplines and among countries, both in the Nordic countries and internationally. An obvious advantage of such cooperation is that a wider range of experiences from different habitats and different socio-economic conditions becomes available and thus provides a more solid basis for developing practical solutions for restoration methods and policies.
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