| 1. |
- Scharn, Ruud, et al.
(författare)
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Vegetation responses to 26 years of warming at Latnjajaure Field Station, northern Sweden
- 2022
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Ingår i: Arctic Science. - 2368-7460. ; 8:3, s. 858-877
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment (ITEX). We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We have measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analysed based on a 7-year Community-Level Interaction Program (CLIP) experiment. The communities had distinct soil moisture conditions, leading to community specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.
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| 2. |
- Scharn, Ruud, et al.
(författare)
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Decreased soil moisture due to warming drives community transitions in the tundra
- 2021
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- Global warming leads to drastic changes in the diversity and structure of Arctic plant communities. Studies of functional diversity within the Arctic tundra biome have improved our understanding of plant responses to warming. However, these studies still show substantial unexplained variation in diversity responses. Complementary to functional diversity, phylogenetic diversity has been useful in climate change studies, but has so far been understudied in the Arctic. Here, we use a 25-year warming experiment to disentangle community responses in Arctic plant phylogenetic diversity across a soil moisture gradient. We found that responses varied over the soil moisture gradient, where meadow communities with intermediate to high soil moisture had a higher magnitude of response. Warming had a negative effect on soil moisture levels in all meadow communities, however meadows with intermediate moisture levels were more sensitive. In these communities, soil moisture loss was associated with earlier snowmelt, resulting in community turnover towards a more heath-like community. This process of "heathification" in the intermediate moisture meadows was driven by the expansion of ericoid and Betula shrubs. In contrast, under a more consistent water supply Salix shrub abundance increased in wet meadows. Due to its lower stature, palatability and decomposability, the increase in heath relative to meadow vegetation can have several large scale effects on the local food web as well as climate. Our study highlights the importance of the hydrological cycle as a driver of vegetation turnover in response to Arctic climate change. The observed patterns in phylogenetic diversity were often driven by contrasting responses of species of the same functional growth form, and could thus provide important complementary information. Thus, phylogenetic diversity is an important tool in disentangling tundra response to environmental change.
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